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Fluorescent nanoparticles present in Coca-Cola and Pepsi-Cola: physiochemical properties, cytotoxicity, biodistribution and digestion studies
Abstract
Foodborne nanoparticles (NPs) have drawn great attention due to human health concerns. This study reports the detection of the presence of fluorescent NPs, about 5 nm, in two of the most popular beverages, Coca-Cola (Coke) and Pepsi-Cola (Pepsi). The NPs contain H, C and O, three elements with a tunable emission and with a quantum yield of 3.3 and 4.3% for Coke and Pepsi, respectively. The presence of sp³-hybridized carbon atoms of alcohols and ethers bonds was confirmed by NMR analysis. The NPs can be taken up by living cells and accumulate within cell membrane and cytoplasm. Evaluation of the acute toxicity of the NPs revealed that the BALB/c mice appeared healthy after administration of a single dose of 2 g kg⁻¹ body weight. Analysis of glutamate pyruvate transaminase (GPT), glutamic oxaloacetic transaminase (GOT), urea and creatinine showed that there were statistically, but not biologically, significant differences in some of these biochemical parameters between the test and control groups. No obvious organ damage or apparent histopathological abnormality was observed in the tested mice. The biodistribution study in major organs indicated that the NPs were easily accumulated in the digestive tract, and they were able to cross the blood–brain barrier and dispersed in the brain. In vitro digestion of the NPs showed a significant fluorescence quenching of the NPs. This work represents the first report of foodborne fluorescent NPs present in Coke and Pepsi, and provides valuable insights into physicochemical properties of these NPs and their toxicity characteristics both in vitro and in vivo.
... In contrast to pyrolysis, the hydrothermal process is one of the most popular and practical methods for synthesizing CDs using various natural resources and chemical compounds. Similar to the hydrothermal process for CD synthesis, processes that treat foods or their components in hot aqueous solutions with high vapor pressure can also produce CDs (Li et al. 2018c;Liu et al. 2012). In fact, it is well known that various foods can be used as excellent carbon precursors for sustainable CD production using this approach . ...
... Li et al. demonstrated that CD generally exhibits low acute oral toxicity under normal conditions and at appropriate doses. The acute toxicity of CD from beer, Coca-Cola, and Pepsi was evaluated at a high dose of 2.0 g/kg body weight in a mouse model (Li et al. 2018c). No significant clinical signs of death or toxicity were observed after oral administration of CDs from beer or cola. ...
... Furthermore, studies on the potential toxicity of CDs conducted to date do not provide specific evidence for negative effects and are rather contradictory. Some studies have shown that CDs are safe in mice at concentrations as high as 2.0 g/kg body weight (Li et al. 2018c), while others have demonstrated that CDs can negatively affect various metabolic processes in mice at concentrations as low as 25 mg/kg body weight ). The differences in these findings may be due to factors other than size, surface chemistry, and concentration that the researchers may not have considered: the mode of administration, which governs pharmacological and other longterm interactions. ...
Carbon dots (CDs), which are emerging as versatile nanomaterials, have gained interest in food packaging and preservation due to their sustainable origin and multifunctional characteristics, such as antimicrobial, antioxidant, and UV‐protective properties. CDs can be synthesized from biomass and have been proposed as functional additives to packaging material to improve the safety and shelf life of the packaged food. Despite these benefits, concerns are raised about their potential toxicity when leached into foods, especially since they belong to the nanomaterial category. Interestingly, foodborne CDs, which are naturally formed in heat‐processed foods and have been consumed by humans for centuries, add a new complexity to the debate. Although there is no definitive evidence linking these endogenous CDs to adverse health effects, some studies suggest their potential to interfere with metabolism in animal models. In addition, the presence of hazardous substances in thermally processed foods, such as polycyclic aromatic hydrocarbons (PAHs), may further complicate safety assessment. This review addresses the paradox of CD from food and packaging sources, highlighting its dual role as both a potentially toxic agent and a beneficial functional material. More extensive research is essential to fully understand the long‐term effects of CD on human health and to determine whether its use in food packaging is truly safe or beneficial.
... Additionally, significant accumulation was found in the liver, brain, and heart 2-6 h after administration, indicating potential blood-brain barrier crossing for ultra-small nanoparticles smaller than 5 nm (Li et al. 2018b). Although Li et al. (2018b) proved that carbon dots can be quenched by saliva, gastric juice, and duodenal-bile juice in vitro digestion experiments, the accumulation and distribution of carbon dots need to be studied deeply to understand their fate and effects on biological systems (Li et al. 2018b). ...
... Additionally, significant accumulation was found in the liver, brain, and heart 2-6 h after administration, indicating potential blood-brain barrier crossing for ultra-small nanoparticles smaller than 5 nm (Li et al. 2018b). Although Li et al. (2018b) proved that carbon dots can be quenched by saliva, gastric juice, and duodenal-bile juice in vitro digestion experiments, the accumulation and distribution of carbon dots need to be studied deeply to understand their fate and effects on biological systems (Li et al. 2018b). Due to this potential health risk, further investigation is necessary into the association between carbon dots and bioactive molecules. ...
... Additionally, significant accumulation was found in the liver, brain, and heart 2-6 h after administration, indicating potential blood-brain barrier crossing for ultra-small nanoparticles smaller than 5 nm (Li et al. 2018b). Although Li et al. (2018b) proved that carbon dots can be quenched by saliva, gastric juice, and duodenal-bile juice in vitro digestion experiments, the accumulation and distribution of carbon dots need to be studied deeply to understand their fate and effects on biological systems (Li et al. 2018b). Due to this potential health risk, further investigation is necessary into the association between carbon dots and bioactive molecules. ...
Discovered in 2004, carbon dots have garnered a major attention due to their unique optical properties, nanoscale size, and cost-effectiveness. Their potential uses are applicable for bioimaging, electronics, and the food industry. Carbon dots are promising tools for detecting contaminants, identifying harmful bacteria, and monitoring essential nutrients. Here, we review the safety risks associated with applying carbon dots in the food industry, focusing on their integration into global food safety frameworks. We highlight recent advancements in the detection capabilities of carbon dots, showcasing their sensitivity and specificity in identifying foodborne pathogens and contaminants. We discuss strategies to mitigate potential health risks, such as optimizing carbon dot synthesis to minimize their toxicity and ensuring thorough regulatory assessments. Current research shows that carbon dots improve food safety, but research is needed to address safety concerns and ensure consumer confidence.
... The button mushroom (Agaricus bisporus), which makes up 70% of total edible fungi, is a sustainable food source and has traditional health benefits [12,13]. It has several medicinal properties such as antioxidant, antimicrobial, anti-inflammatory, antitumor, and anticancer properties [14][15][16][17][18][19] and is a rich nutritional source for proteins, essential amino acids, minerals, vitamins, polysaccharide, and hydrazine derivatives, including agaritine and gyromitrin [15][16][17][18]. Agaritine in A. bisporus has been linked to reducing oxidative stress, but in some studies with mice, it's been considered a potential carcinogen due to its ability to produce free radicals [17]. ...
... The button mushroom (Agaricus bisporus), which makes up 70% of total edible fungi, is a sustainable food source and has traditional health benefits [12,13]. It has several medicinal properties such as antioxidant, antimicrobial, anti-inflammatory, antitumor, and anticancer properties [14][15][16][17][18][19] and is a rich nutritional source for proteins, essential amino acids, minerals, vitamins, polysaccharide, and hydrazine derivatives, including agaritine and gyromitrin [15][16][17][18]. Agaritine in A. bisporus has been linked to reducing oxidative stress, but in some studies with mice, it's been considered a potential carcinogen due to its ability to produce free radicals [17]. ...
... Agaritine in A. bisporus has been linked to reducing oxidative stress, but in some studies with mice, it's been considered a potential carcinogen due to its ability to produce free radicals [17]. Excessive free radicals can damage cells and contribute to neurodegenerative disorders, cancer, Alzheimer's disease, Parkinson's disease, and aging [18]. However, the hydrazine derivatives in mushrooms pose no toxicological risk to humans when consumed in normal amounts. ...
Background
The development of cost-effective, simple, environment-friendly biographene is an area of interest. To accomplish environmentally safe, benign culturing that has advantages over other methods to reduce the graphene oxide (GO), extracellular metabolites from actinobacteria associated with mushrooms were used for the first time.
Methods
Bactericidal effect of GO against methicillin-resistant Staphylococcus aureus, antioxidant activity, and hydroxyapatite-like bone layer formation, gene expression analysis and appropriate biodegradation of the microbe-mediated synthesis of graphene was studied.
Results
Isolated extracellular contents Streptomyces achromogenes sub sp rubradiris reduced nano-GO to graphene (rGO), which was further examined by spectrometry and suggested an efficient conversion and significant reduction in the intensity of all oxygen-containing moieties and shifted crystalline peaks. Electron microscopic results also suggested the reduction of GO layer. In addition, absence of significant toxicity in MG-63 cell line, intentional free radical scavenging prowess, liver and kidney histopathology, and Wistar rat bone regeneration through modulation of OPG/RANKL/RUNX2/ALP pathways show the feasibility of the prepared nano GO.
Conclusions
The study demonstrates the successful synthesis of biographene from actinobacterial extracellular metabolites, its potential biomedical applications, and its promising role in addressing health and environmental concerns.
... The formation process of the CDs during the roasting includes different steps of polymerization, dehydration, nucleation, aggregation, emergence, and blossom [88]. Some other reported food-borneNPs, are the CDs discovered in some popular beverages such as Coca-Cola and commercial beer which have been easily extracted and studied [89,90]. There are many other studies on food-borne green-CDs to evaluate their toxicity and efficacy [28,29,[88][89][90][91][92][93], but it still has potential uncertainty to human health and needs more future examinations. ...
... Some other reported food-borneNPs, are the CDs discovered in some popular beverages such as Coca-Cola and commercial beer which have been easily extracted and studied [89,90]. There are many other studies on food-borne green-CDs to evaluate their toxicity and efficacy [28,29,[88][89][90][91][92][93], but it still has potential uncertainty to human health and needs more future examinations. ...
... Commercial beverages [96], Commercial beer [90], Chinese mature vinegar [94], Nescafe [95] Coca-cola [89] Extraction Ease of synthesis during food/beverages preparation Uncertainty of CD composition ...
Fluorescence imaging via carbon dots (CDs) has found multifarious applications in the biomedical sciences including biosensing, cancer cell bioimaging, drug delivery and tracking therapeutic response. Presently, the latest generation of fluorescence CDs known as green-CDs has attracted ever-increasing attention due to the use of natural sources, low-cost synthesis, nanoscale size, promising biocompatibility, superior photoluminescence, and ease of functionalization for versatile applications, which in turn could have higher priority over the traditional toxic fluorescent agents. In this review, we aim to have a new insight into the engineering green-CDs and their physicochemical properties. Moreover, we discuss the possible applications of green-CDs in self and active targeting, therapeutics delivery, and finally their promising future in cancer theranostics.
... Additionally, human fingernails have been explored as a precursor in microwave-assisted CDs synthesis, producing particles useful in dye sensing and biological imaging [45]. Other sources, such as mango [76], aloe [77], sucrose [78], and Momordica charantia fruits [79], have also been utilized, underscoring the method's adaptability and the broad scope of potential applications for the synthesized CDs. ...
... Additionally, human fingernails have been explored as a precursor in microwave-assisted CDs synthesis, producing particles useful in dye sensing and biological imaging [45]. Other sources, such as mango [76], aloe [77], sucrose [78], and Momordica charantia fruits [79], have also been utilized, underscoring the method s adaptability and the broad scope of potential applications for the synthesized CDs. ...
Carbon dots (CDs) are attracting increasing research attention due to their exceptional attributes, including their biocompatibility, water solubility, minimal toxicity, high photoluminescence, and easy functionalization. Green CDs, derived from natural sources such as fruits and vegetables, present advantages over conventionally produced CDs, such as cost-effectiveness, stability, simplicity, safety, and environmental friendliness. Various methods, including hydrothermal and microwave treatments, are used to synthesize green CDs, which demonstrate strong biocompatibility, stability, and luminescence. These properties give green CDs versatility in their biological applications, such as bioimaging, biosensing, and drug delivery. This review summarizes the prevalent synthesis methods and renewable sources regarding green CDs; examines their optical features; and explores their extensive biological applications, including in bioimaging, biosensing, drug/gene delivery, antimicrobial and antiviral effects, formatting of mathematical components, cancer diagnosis, and pharmaceutical formulations.
... Earlier works have confirmed that the CDs from beer, Coke, and Pepsi can penetrate the blood-brain barrier and enter mice brain tissue (Li et al., 2018;. During the process of transporting to organs with the blood, CDs will spontaneously adsorb blood proteins to form a protein corona, which may affect the original structure and function of the protein, as well as the biological absorption and effects of CDs (Cui et al., 2022). ...
... 3D images of (i) trypsin and its interaction with (j) 20 μg mL −1 , (k) 60 μg mL −1 , (l) 120 μg mL −1 CDs, and (m, n, o, p) corresponding planar analysis. Coca-Cola and Pepsi-Cola that were excreted from mice within 24 h (Li et al., 2018). Meanwhile, the Spanish mackerel CDs were absorbed by the intestine and entered the organs through blood circulation. ...
Nanoparticles with small sizes formed in the process of food thermal treatment have gained substantial attention due to their safety uncertainty and latent risks to human health. Herein, the physicochemical features of fluorescent carbon dots (CDs) from roasted Spanish mackerel were studied, it was found that the size distribution, fluorescence properties, surface groups, and formation process of CDs were highly dependent on the roasting time of Spanish mackerel. The interaction of CDs with digestive proteases resulted in the structural change and activity inhibition of proteases. When the concentration of CDs was 120 μg mL ⁻¹ , the enzyme activity of pepsin and trypsin was reduced from 100% to 75.95% and 78.5%, respectively. The CDs caused static fluorescence quenching of pepsin and trypsin as confirmed by the fluorescence analysis. After oral administration, CDs can be transported to the main organs through the blood. The cytotoxicity assessment revealed that the cell viability decreased with the prolonging of roasting time. The CDs roasted at 230°C for 40 min showed a significant hemolytic effect even at a low concentration of 0.5 mg mL ⁻¹ . Moreover, the cellular uptake level and pathway of CDs were significantly affected by blood protein adsorption. This study helps to evaluate the in vivo biodistribution, the interaction with proteases during gastrointestinal digestion, and the cellular uptake of CDs after transport through the blood, providing a theoretical basis for revealing the potential effects of foodborne nanoparticles.
... 55 The physical properties of CDs are related to the composition and the way the food is processed, which creates variance in the CDs properties. CDs have been successfully extracted during the thermal processing of baked lamb, 52 pizza, 54 coffee, 56 commercial beverages, 57 grilled fish, 58 roast beef, 59 roast chicken, 60 mature vinegar, 61,62 Coca-Cola, 63 and roasted pork. 64 The properties and the safety of CDs while processing these foods are shown in Table 2. ...
... Still, CDs have good biocompatibility when absorbed into the living cells, colonizing the cytoplasm instead of the nucleus. 63 They freely enter human cells such as MC3T3-E1 and HepG2 cells through the cell membrane into the cytoplasmic region. Nevertheless, no serious toxic effects have been observed in vitro and in vivo models. ...
Nanoparticles (NPs) are small-sized, with high surface activity and antibacterial and antioxidant properties. As a result, some NPs are used as functional ingredients in food additives, food packaging materials, nutrient delivery, nanopesticides, animal feeds, and fertilizers to improve the bioavailability, quality, and performance complement or upgrade. However, the widespread use of NPs in the industry increases the exposure risk of NPs to humans due to their migration from the environment to food. Nevertheless, some NPs, such as carbon dots, NPs found in various thermally processed foods, are also naturally produced from the food during food processing. Given their excellent ability to penetrate biopermeable barriers, the potential safety hazards of NPs on human health have attracted increased attention. Herein, three emerging NPs are introduced including carbon-based NPs (e.g., CNTs), nanoselenium NPs (SeNPs), and rare earth oxide NPs (e.g., CeO2 NPs). In addition, their applications in the food industry, absorption pathways into the human body, and potential risk mechanisms are discussed. Challenges and prospects for the use of NPs in food are also proposed.
... The existence of fluorescent CNDs in beer and soft drinks was investigated in detail by Mingqian Tan and co-authors. [2][3][4] Thus, teachers might firstly refer to Refs. 2-4 for detailed proofs. ...
... This might be due to the fact that the quantum yield of CNDs in beer and cola is quite low, leading to a higher quality of optical filter and a stronger excitation source needing to be introduced. [2][3][4] Therefore, to observe the green fluorescent image from the onion cells, we combined a 405-nm laser diode and SVBONY G-CCD filter while a 532-nm laser and SVBONY R-CCD were employed to detect the red one. The corresponding apparatus are shown in Fig. 3. Figure 4 describes the whole experimental setup for onion cell imaging. ...
This article describes a simple way to introduce nanomaterials using the presence of carbon nanodots (CNDs) in widely available food. Budweiser ® beer and Coca-Cola ® , commercial foods that are commonly accessible, were utilized to demonstrate the optical property of nanoparticles. Specifically, green and violet laser pointers were employed for the observation of excitation-dependent photoluminescence of CNDs. To represent the application of CNDs, we obtained multiple-color emissions in onion cells that were imaged by using Budweiser beer and Coca-Cola as a dye. The demonstration could offer a perspective on the use of food in teaching nanomaterials at the high school and undergraduate levels.
... Each fruit contains around ten seeds, some coloured and some not, grouped in bunches. [4]. According to [2], The kola tree is thought to have originated in Central Africa, and according to these authors, the plant can be found in West Africa in Senegal, Togo and Sierra Leone, among other places. ...
Cola verticillata (Sterculiaceae) is a plant that produces nuts renowned for their ceremonial, cultural, medicinal and above all economic value in Africa. The study consisted in evaluating the cytotoxic and genotoxic effects of the aqueous extract of the plant's nuts on the Zonocerus variegatus model. Male and adult locusts were treated with increasing concentrations of 5, 10, 20, 30 and 40 µg/ml. The 0.01 ml/mg extract was administered intraperitoneal and 96 h post-treatment the grasshoppers were killed, dissected and the testicular follicles removed for smear preparation. Chromosomal examinations revealed that the aqueous extract of C. verticillata induced a significant regression of the meiotic index, followed by a significant increase in the chiasmatic frequency in a concentration-dependent manner and in comparison with the control group. In addition to chromosome bridges, chromosome breaks, sticky chromosomes and leak chromosomes were observed mainly at 40 µg/ml. These results show that Cola extract is cytotoxic and genotoxic because it slowed down meiosis while also inducing multiple chromosomal abnormalities with clastogenic effects in the male Z. variegatus breeder. The results of this study call for populations to consume kola nuts (Cola verticillata) intermittently if the cytotoxic and genotoxic effects are not reversed.
... The CDs' generation in food was first established in 2012 when Sk et al. demonstrated the presence of CDs in food caramels [2]. Since then, evidence has continued to emerge, and while some limitations remain, it has become clear that CDs are common in most daily foods, including meats [3][4][5][6], baked foods [7][8][9], beverages [10,11], and food dressings [12,13]. Thus, the daily and total consumption of CDs among the population is considerably high [14]. ...
Carbon nanodots (CDs) are commonly found in food products and have attracted significant attention from food scientists. There is a high probability of CD exposure in humans, but its impacts on health are unclear. Therefore, health effects associated with CD consumption should be investigated. In this study, we attempted to create a model system of the Maillard reaction between cystine and glucose using a simple cooking approach. The CDs (CG-CDs) were isolated from cystine-glucose-based Maillard reaction products and characterized using fluorescence spectroscopy, X-ray diffractometer (XRD), and transmission electron microscope (TEM). Furthermore, human mesenchymal stem cells (hMCs) were used as a model to unravel the CDs’ cytotoxic properties. The physiochemical assessment revealed that CG-CDs emit excitation-dependent fluorescence and possess a circular shape with sizes ranging from 2 to 13 nm. CG-CDs are predominantly composed of carbon, oxygen, and sulfur. The results of the cytotoxicity evaluation indicate good biocompatibility, where no severe toxicity was observed in hMCs up to 400 μg/mL. The DPPH assay demonstrated that CDs exert potent antioxidant abilities. The qPCR analysis revealed that CDs promote the downregulation of the key regulatory genes, PPARγ, C/EBPα, SREBP-1, and HMGCR, coupled with the upregulation of anti-inflammatory genes. Our findings suggested that, along with their excellent biocompatibility, CG-CDs may offer positive health outcomes by modulating critical genes involved in lipogenesis, homeostasis, and obesity pathogenesis.
... A simulated in vitro digestion model was used to evaluate the lipid digestion of astaxanthin-loaded HIPPEs and the bioaccessibility of astaxanthin (S. Li, Jiang, Wang, Cong, & Tan, 2018). Simulated saliva, simulated gastric juice, and simulated intestinal juice during digestion are prepared in advance according to previous research methods (Miao et al., 2021). ...
Food-grade high internal phase Pickering emulsions (HIPPEs) stabilized by protein-based particles have received widespread attention because of their potential applications in the food industry. Herein, HIPPEs stabilized by sea bass protein (SBP) microgel particles were prepared using a simple one-step method. Its internal phase volume fraction was as high as 88% oil-in-water emulsion. The impact of SBP microgel particles concentration on the physical and chemical properties of HIPPEs was investigated. The SBP microgel particles improved the environmental stability of HIPPEs. Confocal laser scanning microscope (CLSM) and cryo-scanning electron microscope (cryo-SEM) images showed a three-dimensional network structure formed around oil droplets through SBP microgel particles. The average particles size of the HIPPEs droplets decreased with the increased concentration of SBP microgel particles. In rheological analysis, as the concentration of SBP microgel particles increased, HIPPEs showed higher viscoelasticity, excellent recovery, and thixotropy, which further proved the potential application of HIPPEs in 3D printing. The physical and chemical stability of astaxanthin was improved after encapsulation of HIPPEs. Further, the lipolysis degree of HIPPEs and the bioaccessibility of astaxanthin during in vitro digestion were improved also by the SBP microgel particles. Interestingly, the bioaccessibility of astaxanthin in HIPPEs stabilized by 4 wt% SBP microgel particles reached 51.17%. Three-dimensional (3D) printing experiments confirmed the extrudability, printing performance, and self-supporting properties of HIPPEs. In short, the HIPPEs stabilized by SBP microgel particles could be used as a delivery vehicle for astaxanthin, and the HIPPEs loaded with astaxanthin might have potential as a 3D printing material for edible functional foods.
... The absolute diversity of the physicochemical features of NPs also develops research questions regarding their toxic effects [9,22]. Thereby, it is mandatory to determine the interactions of NPs with cells and biomolecules [23,24]. This leads to the emergence of the field of "Nanotoxicology" that aimed at demonstrating data regarding the nanotoxicity potential and the biochemical and structural alterations in vivo [25], due to the potential of deposition of stable NPs and subsequent induced nanotoxicity [26]. ...
Iron oxide nanoparticles (IONPs) are increasingly being employed for in vivo biomedical nanotheranostic applications. The development of novel IONPs should be accompanied by careful scrutiny of their biocompatibility. Herein, we studied the effect of administration of three formulations of IONPs, based on their starting materials along with synthesizing methods, IONPs-chloride, IONPs-lactate, and IONPs-nitrate, on biochemical and ultrastructural aspects. Different techniques were utilized to assess the effect of different starting materials on the physical, morphological, chemical, surface area, magnetic, and particle size distribution accompanied with their surface charge properties. Their nanoscale sizes were below 40 nm and demonstrated surface up to 69m2/g, and increased magnetization of 71.273 emu/g. Moreover, we investigated the effects of an oral IONP administration (100 mg/kg/day) in rat for 14 days. The liver enzymatic functions were investigated. Liver and brain tissues were analyzed for oxidative stress. Finally, a transmission electron microscope (TEM) and inductively coupled plasma optical emission spectrometer (ICP-OES) were employed to investigate the ultrastructural alterations and to estimate content of iron in the selected tissues of IONP-exposed rats. This study showed that magnetite IONPs-chloride exhibited the safest toxicological profile and thus could be regarded as a promising nanotherapeutic candidate for brain or liver disorders.
... Besides ENMs, abundant amounts of nanoparticles, which were spontaneously assembled by food endogenous components during food processing, widely exist in daily foods (Cao et al., 2017;Cong et al., 2019;Jiang, Shi, Li, Xiong, & Sun, 2019;Ke et al., 2017;Li, Jiang, Wang, Cong, & Tan, 2018;Lin et al., 2017;Wang et al., 2019). In freshwater clam (Corbicula fluminea Muller) soup, a large amount of nanoparticles with sizes ranged from 40 nm to 149 nm formed during boiling (Gao et al., 2021;Ke, Zhou, Lu, Gao, & Rao, 2011). ...
Safety concerns arose on the interaction between nanoparticles in food and intestinal tract. Food components could spontaneously assemble into a large number of nanoparticles during food processing. These nanoparticles may possess physiological effects differed from those of constituent components, are worth paying attention to, but are barely investigated yet, especially on their interaction with intestinal tract. Porcine bone soup is rich in nanoparticles, which can directly interact with oral macrophages disclosed by our previous study. In this study, the effects of bone soup nanoparticles on intestinal barrier function were subsequently evaluated on Caco-2 cell monolayers. The results revealed the nanoparticles did not develop but restore intestinal barrier dysfunction compared with engineered nanoparticles, indicated by barrier integrity, sodium fluorescein permeability, tight junctions and adherent junctions related proteins. These results showed the potential of bone soup nanoparticles on improving intestinal disorders, which resonated with traditional knowledge on the efficacies of bone soup.
... The composition of most foods contains carbon, hydrogen, oxygen and nitrogen, and many nanoparticles are produced during food manufacturing process. Carbon quantum dots (CQDs) can be easily produced via heating reaction and are found in most food, like Coca-Cola and Pepsi-Cola 66 . The mice fed with high dose Coca-Cola and Pepsi-Cola CQDs do not appear obvious organ damage, and CQDs could be digested in the small intestine or cleared through the liver. ...
White spot syndrome virus (WSSV) is the causative agent of white spot syndrome (WSS), a disease that has led to severe mortality rates in cultured shrimp all over the world. The WSSV is a large, ellipsoid, enveloped double-stranded DNA virus with a wide host range among crustaceans. Currently, the main antiviral method is to block the receptor of the host cell membrane using recombinant viral proteins or virus antiserum. In addition to interference with the ligand-receptor binding, disrupting the structure of the virus envelope may also be a means to combat the viral infection. Carbon quantum dots (CQDs) are carbonaceous nanoparticles that have many advantageous characteristics, including small size, low cytotoxicity, cheap, and ease of production and modification. Polyamine-modified CQDs (polyamine CQDs) with strong antibacterial ability have been identified, previously. In this study, polyamine CQDs are shown to attach to the WSSV envelope and inhibit the virus infection, with a dose-dependent effect. The results also show that polyamine CQDs can upregulate several immune genes in shrimp and reduce the mortality upon WSSV infection. This is first study to identify that polyamine CQDs could against the virus. These results, indeed, provide a direction to develop effective antiviral strategies or therapeutic methods using polyamine CQDs in aquaculture.
... However, the exact effects of these nanomaterials on human health and the environment remain unclear [4][5][6]. One of the main concerns is to determine the interactions of different types of nanoparticles (NPs), as a function of their shape, size and surface modifications, with biological cells [7,8]. This has led to the emergence of "Nanotoxicology" as an independent field of research, that provides data regarding the toxicity of nanoparticles. ...
Aim
In this study, in vivo biodistribution, clearness and toxicity of curcumin capped iron oxide nanoparticles (Cur-IONPs) were addressed in different body organs.
Materials and methods
The physicochemical properties of the prepared Cur-IONPs were investigated. Long term (3 weeks) biodistribution, clearness and toxicity were assessed for a single-dose administration of Cur-IONPs (5 mg/kg). The iron content in liver, kidney, spleen and brain was quantified using atomic absorption spectroscopy. Serum biochemical parameters were also measured.
Key findings
The integrated in vivo results demonstrated that Cur-IONPs was mostly taken up in the liver and spleen reaching its highest levels on days 1 and 2, respectively. In the brain, the results showed significant accumulation of Cur-IONPs between 1 h to 1-day post injection. This represented the successful penetration Cur-IONPs across the blood-brain barrier. Serum biochemical analysis demonstrated a temporal disturbance in the performance of body organs. Also, the body weights showed no alteration throughout the experiment.
Significance
It has been deduced that the promising green synthesized Cur-IONPs as an “All in One” nanoplatform is safe enough to be used in diagnostic and therapeutic purposes.
... This finding indicated that the Salmo salar L. CQDs distribution within the cells changed with the increase of their concentration and the CQDs were transferred from the cytoplasm to nucleus at higher concentrations. The concentration effect on the distribution of the Salmo salar L. CQDs in the cell is quite different from what we reported previously in the cell cytoplasm (Li, Jiang, Wang, Cong, & Tan, 2018). In contrast to the untreated control, the NRK cells treated with 3 and 6 mg mL −1 of Salmo salar L. CQDs showed slight cellular shrinking, which is a feature of apoptotic cells (Mirshafiee et al., 2018). ...
The endogenous carbon quantum dots (CQDs) produced during food processing have potential uncertainty to human health. The objective of this study was to investigate the formation, biodistribution and cytotoxicity of CQDs in roasted Atlantic salmon (Salmo salar Linnaeus). The X-ray photoelectron spectroscopy (XPS) analysis showed that the CQDs were mainly composed of carbon, oxygen and nitrogen. The morphology, functional groups and optical properties were highly dependent on the roasting time. In vivo experiments in mice demonstrated that the CQDs distributed in the digestive tract, kidney, liver, and even brain, which indicated that they could cross the blood–brain barrier. The cell imaging results indicated that the CQDs could readily gain access to the normal rat kidney (NRK) cells, and caused autophagosome formation. The proportion of live cells decreased to 34.62% at 6 mg mL ⁻¹ of CQDs, and the energy generation route was changed from aerobic to glycolytic metabolism.
... 43 The fluorescence signals in the lungs and kidneys of mice treated with FNPs were also stronger than in control mice, which is consistent with the report of fluorescent nanoparticles derived from Coca and Pepsi-Cola in these organs. 44 However, no fluorescence signal was observed in the brain, heart, and spleen, suggesting that the biodistribution of the pizza FNPs was also organ dependent. The semiquantitative fluorescence intensity in major organs is shown in Fig. 7b, which reveals that the ultra-small nanoparticles are able to cross the physiological barrier of the intestine and thus can be delivered by the blood or lymph throughout the main organs of the body. ...
Food-borne nanoparticles are generated during the thermal processing of various consumed foods that are of great concern due to their unique properties. In this study, the presence of fluorescent nanoparticles (FNPs) in pizza, their biodistribution and cytotoxicity were investigated. The spherical FNPs have a diameter of about 3.33 nm. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy analysis revealed that they contained 68.21% C, 27.44% O, 2.75% N and 1.60% S, and the functional groups on their surface included -OH, COOH, C=C, -NH2 and C=O. In vitro and in vivo biodistribution of pizza FNPs was evaluated using normal rat kidney (NRK) cells, onion epidermal cells, Caenorhabditis elegans and mice. Furthermore, the produced FNPs were found to cause cell cycle arrest at G0/G1 phase in NRK cells, and resulted in cell apoptosis. The outcome of this research offers an important insight to the nature of thermal processing-induced nanoparticles and their in vivo and in vitro biological effects.
Carbon quantum dots (CQDs) have entered the world of food science and technology (FST) as a low-cost, sustainable, biodegradable, and functional nanoparticle alternative. In the last 5 years, a large number of articles (more than 100) regarding CQD synthesis from food waste and its valorization in FST were published in peer-reviewed journals. CQD properties depend upon the type of the precursor, synthesis method, size, and processing parameters. In the literature, there have been numerous application areas of CQDs offered for FST, especially in the last 5 years. This review study aims to combine and summarize all the information related to FST in one article. Therefore, this comprehensive review article provides a thorough summary of (i) the CQD food waste precursors, (ii) their synthesizing methods, (iii) the properties, and (iv) the application areas in FST. It also discusses and identifies some research needs.
Graphical Abstract
Green carbon dots (GCDs) have emerged as a potential category of nanomaterials owing to their distinctive attributes, which include biocompatibility, low toxicity, increased photoluminescence (PL), and environmental sustainability. This paper thoroughly examines the synthesis of GCDs from renewable carbon sources, their unique features, and their extensive uses in theranostics, including bioimaging, drug administration, photothermal treatment, and molecular diagnostics. The synthesis methods, including hydrothermal, microwave-assisted, and laser ablation procedures, are examined comprehensively, emphasizing their benefits and drawbacks. The study highlights the significance of surface functionalization and heteroatom doping in improving the optical and electrical characteristics of GCDs. Additionally, the capabilities of GCDs in sustainable nanotechnology and their contribution to resolving environmental and medicinal issues are analyzed. This article seeks to elucidate GCDs, including their synthesis, characteristics, and uses, while also delineating prospective research avenues to address current limits and enhance their potential in biological and environmental domains.
Carbon quantum dots (CQDs) are the newest members of the carbon-based nanomaterials family. These zero-dimensional carbon nanomaterials have been recently used for various applications ranging from electronics to biomedical science due to their relatively simple synthesis process and excellent functional properties. Besides, their safety, non-toxicity, environmental friendliness, and economics have brought them tremendous acceptance in research and industry. Recently, green synthesis of CQDs using sustainable resources such as biomass has been increasingly explored. Attempts have been made to synthesize CQDs from various renewable resources, such as biowaste from agriculture, forestry, microbial biomass, or food processing industries. Fruit processing waste, including peels, refuse, pomaces, and seeds, is one of the biowastes produced in large quantities by the food processing industry. These fruit wastes are carbon-rich sources and can serve as economic and sustainable raw materials for the synthesis of functional CQDs. Since these wastes are rich in polyphenols, the CQDs synthesized using them comprise various surface functional groups, resulting in excellent functional properties. This review discusses the sustainable production of CQDs exclusively from fruit wastes and their properties. Additionally, further surface functionalization of CQDs aiming at the enhancement of their functional properties was discussed. Finally, ongoing research on using fruit waste-derived CQDs as sustainable multifunctional materials in food packaging was reviewed, while challenges and prospects in this research field were highlighted.
Background: Increasing concerns have arisenabout the chronic ingestion of fluorescent carbon dots (CDs) in food and their impact on male fertility. This investigation focused on the effects of CDs on the gut-testis axis, particularly on dysbiosis of the gut microbiota and consequent reproductive health implications.
Results: Carbon dots isolated from commercial cola were subjected to a 15-week study, revealing significant impairments in sperm function, including decreased sperm acrosome function and DNA integrity. Transcriptomic insights link the observed reproductive toxicity to alterations in the IL-17 signaling pathway and disruptions in fatty acid and tryptophan metabolism, suggesting a bacterial origin. Notably, metagenomic analyses revealed a shift in the gut microbiota composition, marked by an increase in the abundance oflipopolysaccharide-producing bacteria and a decrease in the abundance of beneficial, anti-inflammatory probiotics such as Bacteroides acidifaciens and Akkermansia muciniphila. This microbial imbalance prompts increased lipopolysaccharide (LPS) production, leading to intestinal barrier damage and systemic inflammation. Furthermore, disruptions in tryptophan metabolism, as evidenced by diminished levels of indole and kynurenine, were linked to an exacerbated inflammatory state and barrier dysfunction. Collectively, these findings elucidate a mechanism by which foodborne CDs trigger reproductive toxicity, beginning with gut microbiota dysbiosis, increasing systemic inflammation, and culminating in metabolic and reproductive disruption.
Conclusions: Our study highlights the significant role of the gut microbiota in reproductive toxicity induced by chronic consumption of foodborne CDs, identifying the gut-testis axis as a critical mediator. These insights advocate for interventions targeting the gut microbiota balance to mitigate the reproductive health risks associated with foodborne nanoparticles.
Nanoparticle (NP) applications aiming to boost plant biomass production and enhance the nutritional quality of crops hae proven to be a valuable ally in enhancing agricultural output. They contribute to greater food accessibility for a growing and vulnerable population. These nanoscale particles are commonly used in agriculture as fertilizers, pesticides, plant growth promoters, seed treatments, opportune plant disease detection, monitoring soil and water quality, identification and detection of toxic agrochemicals, and soil and water remediation. In addition to the countless NP applications in food and agriculture, it is possible to highlight many others, such as medicine and electronics. However, it is crucial to emphasize the imperative need for thorough NP characterization beyond these applications. Therefore, analytical methods are proposed to determine NPs’ physicochemical properties, such as composition, crystal structure, size, shape, surface charge, morphology, and specific surface area, detaching the inductively coupled plasma mass spectrometry (ICP-MS) that allows the reliable elemental composition quantification mainly in metallic NPs. As a result, this review highlights studies involving NPs in agriculture and their consequential effects on plants, with a specific focus on analyses conducted through ICP-MS. Given the numerous applications of NPs in this field, it is essential to address their presence and increase in the environment and humans since biomagnification and biotransformation effects are studies that should be further developed. In light of this, the demand for rapid, innovative, and sensitive analytical methods for the characterization of NPs remains paramount.
Food-based carbon dots (CDs) hold significant importance across various fields, ranging from biomedical applications to environmental and food industries. These CDs offer unique advantages over traditional carbon nanomaterials, including affordability, biodegradability, ease of operation, and multiple bioactivities. This work aims to provide a comprehensive overview of recent developments in food-based CDs, focusing on their characteristics, properties, therapeutic applications in biomedicine, and safety assessment methods. The review highlights the potential of food-based CDs in biomedical applications, including antibacterial, antifungal, antivirus, anticancer, and anti-immune hyperactivity. Furthermore, current strategies employed for evaluating the safety of food-based CDs have also been reported. In conclusion, this review offers valuable insights into their potential across diverse sectors and underscores the significance of safety assessment measures to facilitate their continued advancement and application.
This review describes the application of carbon dots in the development of sustainable technologies for food safety and quality. Carbon dots (CDs) are surface-functionalized and minuscule in size, with controlled fluorescence, high environmental sensitivity, and a range of remarkable photochemical properties. Green CDs are now the subject of extensive study due to their potential applications in a wide range of fields, such as nano sensing, bio imaging, and photo catalysis. Synthesizing CDs involves the top-down strategy, which includes splitting the bigger carbon molecule into nanoscale particles, and the bottom-up methodology, which involves producing CDs from small carbon units. The problems in the food supply chain are very prominent, from farm to fork that include chemical, microbiological and human hygiene. CDs have recently garnered interest because of the straightforward synthesis method, high biocompatibility, and potential for a variety of innovative applications. CDs were prepared from any carbon source, such as food, food waste, plants, chemicals, and graphene. CDs may be extracted naturally from some foods, such as honey, caramels, and sugar beet molasses. The rapid detection of dietary nutrients and toxins has sparked considerable attention, and nanomaterials-based fluorescence sensing has great promise for establishing exceptionally selective and sensitive identification procedures for food safety testing. Carbon dots have a promising future in fluorescence detection of contaminants due to their significant properties. Carbon dot sensors have capacity in the food sensing sector, since food samples include a variety of components that might create interferences, more innovative approaches to bind with CDs are necessary to develop specific sensing probes.
Although the presence of foodborne nanoparticles was confirmed in grilled fish in a previous study, the evaluation of potential health risks of these NPs was insufficient. In the present study, the potential toxicity of onion-like carbon nanoparticles (OCNPs) separated from grilled turbot Scophthalmus maximus L. was evaluated using mouse osteoblasts cells model and zebrafish (Danio rerio) model. Cytotoxicity evaluation revealed that the OCNPs penetrated into the MC3T3-E1 cells without arousing cell morphology changes. No evident apoptosis or damage of cells was observed with increasing OCNPs’ concentration to 20 mg/mL. In the hemolysis test, OCNPs did not show an obvious hemolysis effect on red blood cells. In the acute toxicity test, the LC50 value (212.431 mg/L) of OCNPs to zebrafish showed a weak acute toxicity. In subacute toxicity test, after exposure to OCNPs (30 mg/L, 40 mg/L) for 10 days, a significant increase of reactive oxygen species level of zebrafish was observed. Meanwhile, redundant ROS content caused inhibition to several antioxidant enzymes and induced lipid and protein peroxidation damages according to the upregulation of malondialdehyde and protein carbonyl levels. The chronic toxicity test results indicated that oxidative stress was only observed in the high concentration group of OCNPs-treated zebrafish.
In the last decade, research on ‘carbon dot’ (CD) has grown exponentially with its exhilarating aspects in biomedical, environmental remediation, energy-related applications, and many others. However, with the rampant pace of publications, few rudimentary questions over this nanoparticle have been overlooked and continued to be unanswered either consciously or unconsciously. Naturally, it is fostering a negative impact on CD research and confining its enormous potential within the laboratory. Herein, we have tried to decode the interconnected factors that are shackling further growth or transition of CD to industry and ultimately to market. Towards this, we have explicated the inconsistent nomenclature, multifarious synthesis precursors and approaches, the ambiguities over purification, and the nature of fluorescence. We have also audited the nanotoxicity issue of CD and elucidated why CD is disparate from its counterparts over nanotoxicity issues. Then we raised questions with a few examples on otherwise so mesmeric applications of CD. In a first of its kind, we have provided an industrial outlook of the CD and delineated paths to break the barrier. Overall, we believe attention to a few fundamental concerns associated with CD will accelerate its transition to mankind. 〈PE-FRONTEND〉
Background
Shrimp aquaculture has suffered huge economic losses over the past decade due to the outbreak of acute hepatopancreatic necrosis disease (AHPND), which is mainly caused by the bacteria Vibrio parahaemolyticus ( V. parahaemolyticus ) with the virulence pVA1 plasmid, which encodes a secretory photorhabdus insect-related (Pir) toxin composed of PirA and PirB proteins. The Pir toxin mainly attacks the hepatopancreas, a major metabolic organ in shrimp, thereby causing necrosis and loss of function. The pandemic of antibiotic-resistant strains makes the impact worse.
Methods
Mild pyrolysis of a mixture of polysaccharide dextran 70 and the crosslinker 1,8-diaminooctane at 180 ℃ for 3 h to form carbonized nanogels (DAO/DEX-CNGs) through controlled cross-linking and carbonization. The multifunctional therapeutic CNGs inherit nanogel-like structures and functional groups from their precursor molecules.
Results
DAO/DEX-CNGs manifest broad-spectrum antibacterial activity against Vibrio parahaemolyticus responsible for AHPND and even multiple drug-resistant strains. The polymer-like structures and functional groups on graphitic-carbon within the CNGs exhibit multiple treatment effects, including disruption of bacterial membranes, elevating bacterial oxidative stress, and neutralization of PirAB toxins. The inhibition of Vibrio in the midgut of infected shrimp, protection of hepatopancreas tissue from Pir toxin, and suppressing overstimulation of the immune system in severe V. parahaemolyticus infection, revealing that CNGs can effectively guard shrimp from Vibrio invasion. Moreover, shrimps fed with DAO/DEX-CNGs were carefully examined, such as the expression of the immune-related genes, hepatopancreas biopsy, and intestinal microbiota. Few adverse effects on shrimps were observed.
Conclusion
Our work proposes brand-new applications of multifunctional carbon-based nanomaterials as efficient anti- Vibrio agents in the aquatic industry that hold great potential as feed additives to reduce antibiotic overuse in aquaculture.
Graphical Abstract
Background: Shrimp aquaculture has suffered huge economic losses over the past decade due to the outbreak of acute hepatopancreatic necrosis disease (AHPND), which is mainly caused by the bacteria Vibrio parahaemolyticus (V. parahaemolyticus) with the virulence pVA1 plasmid, which encodes a secretory photorhabdus insect-related (Pir) toxin composed of PirA and PirB proteins. The Pir toxin mainly attacks the hepatopancreas, a major metabolic organ in shrimp, thereby causing necrosis and loss of function. The pandemic of antibiotic-resistant strains makes the impact worse.
Methods: Mild pyrolysis of a mixture of polysaccharide dextran 70 and the crosslinker 1,8-diaminooctane at 180 ℃ for 3 h to form carbonized nanogels (DAO/DEX-CNGs) through controlled cross-linking and carbonization. The multifunctional therapeutic CNGs inherit nanogel-like structures and functional groups from their precursor molecules.
Results: DAO/DEX-CNGs manifest broad-spectrum antibacterial activity against Vibrio parahaemolyticus responsible for AHPND and even multiple drug-resistant strains. The polymer-like structures and functional groups on graphitic-carbon within the CNGs exhibit multiple treatment effects, including disruption of bacterial membranes, elevating bacterial oxidative stress, and neuralization of PirAB toxins. The inhibition of Vibrio in the midgut of infected shrimp, protection of hepatopancreas tissue from Pir toxin, and suppressing overstimulation of the immune system in severe V. parahaemolyticus infection, revealing that CNGs can effectively guard shrimp from Vibrio invasion. Moreover, shrimps fed with DAO/DEX-CNGs were carefully examined, such as the expression of the immune-related genes, hepatopancreas biopsy, and intestinal microbiota. Few adverse effects on shrimps were observed.
Conclusion: Our work proposes brand-new applications of multifunctional carbon-based nanomaterials as efficient anti-Vibrio agents in the aquatic industry that hold great potential as feed additives to reduce antibiotic overuse in aquaculture.
Background/Issues
The applications of nanoscience and nanotechnology in agriculture and food sector are relatively recent. Substantial acquisitions due to the effects of nanomaterials in these fields have expanded their usage. Intriguingly, nanomaterials demonstrate several biological complications in studies. Hence, the recent entrance of this technology into the human food chain has arisen concerns.
Major Advances
Here we review the possibility of naturally occurring nanomaterials existence in food. The routes of engineered nanomaterials entry through the ecosystem to the plant and animal food and their bioaccumulation and biomagnification are delineated. Despite the limitations in nanomaterial toxicity assessment, awareness about nanomaterial’s movement through different trophic levels and their effects on food animals and plants might help the risk analysis of these particles in the food chain.
Background
Food can be considered as a natural pool of biopolymer-based colloidal particles diverse in size, morphology, and functionalities. There remains considerable controversy on whether these particles can be absorbed from the intestinal lumen in their intact form even though numerous studies have confirmed the possibility of the absorption of intact nanoparticles across the intestinal wall.
Scope and approach
In this review, we comprehensively summarize the absorption process of nanoparticles, including mucus-penetrating, cellular uptake, and intracellular transportation. We then perform a deep insight into the absorption of food colloidal particles composed of protein, lipid and carbohydrate. The in-vivo transportation and biodistribution of nanoparticles is then summarized. We also specially discuss the dynamic colloidal aspects of food components which is of great importance to the food digestion and absorption. Finally, we analyze the safety issue of food nanoparticles since an increasing concern on this arises in the past decades.
Key findings and conclusions
External nanoparticles can be absorbed into cells through endocytosis, which can occur via different mechanisms. Like various fabricated nanoparticles, food colloidal particles potentially can also be absorbed in their intact form. However, previous studies rarely touch upon the absorption, biological fate, potential health effects, and safety of these colloidal particles. Their dynamic formation and disassembly process is also ignored. All these issues are of great importance to the food digestion and absorption mechanism and worth to be thoroughly studied. We attempt to coin all these relevant studies as “Colloidal Nutrition Science”, which aim to understand the food-body interaction from colloidal aspects.
Fluorescence nanoparticles (FNs) are a type of nano-dots generated during baking process, and their safety on organism is unclear and little is known to their cytotoxicity. In this study, the FNs from instant coffee were purified and characterized. The FNs with an average size about 2.08 nm emitted bright blue fluorescence with lifetime about 2.74 ns. The element and functional groups were analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, respectively. The results indicated that these FNs were internalized in lysosomes and induced apoptosis of normal rat kidney (NRK) and Caco-2 cells. While, the pan-caspase inhibitor, Z-VAD-FMK didn't decrease the rate of apoptosis and cell death of the FNs-treated NRK and Caco-2 cells. These internalized FNs enlarged lysosomes, decreased lysosomal enzyme degradation activity and increased lysosomal pH value. Partial co-localization of receptor-interacting serine-threonine kinase 3 (RIPK3) to lysosomes in FNs-treated cells was observed, and the amount of RIPK1 and RIPK3 increased after treatment with FNs. The results demonstrated that the FNs from instant coffee induced lysosomal membrane permeabilization and initiated necroptosis.
Fluorescent nanoparticles (FNs) were identified from roasted sweet potato with a particle size of 7.0, 2.8, 2.4 nm for peel FNs, and 2.3, 1.9, 2.2 nm for pulp FNs after roasting at 250 °C for 20, 40, and 60 min, respectively. Blue fluorescence of FNs was observed under ultra-violet light excitation. The fluorescence intensity of the FNs increased when they were transferred from acidic to alkaline environment, and the FNs showed good photostability. The fluorescence of peel and pulp FNs was quenched 42.65% and 35.59%, respectively, in vitro digestion. The FNs could be absorbed by the digestive tracts of mice and enter liver, heart, kidney, brain, lung and testis. A distinct interaction between FNs and dopamine was confirmed in weakly alkaline aqueous solution. This work provided useful information in understanding the property of FNs generated in plant-based food of roasted sweet potato during normal cooking.
Background
Fluorescent carbon dots (CDs) are a novel class of carbon-based nanomaterials that were discovered in 2004. However, nobody knew that CDs existed in food items naturally until 2012. Properties of nanosize materials are distinct from those of their bulk materials due to the particle size and accordingly alter their bioavailability and/or biocompatibility. Therefore, the potential health risk of nanoparticles in food has drawn massive attention. Currently, almost all studies regarding the biosafety of nanoparticles in food have mainly focused on engineered nanoparticles used as food additives and have excluded the endogenous nanoparticles in food. Therefore, investigation of the properties of food-borne fluorescent CDs and their potential health risk to humans is of great significance.
Scope and approach
This review summarizes the existing literature on fluorescent carbon dots (CDs) in food, with particular attention to their properties, formation process, and the potential health risks posed to consumers. The knowledge gap between food-borne nanoparticles and their potential risks is identified, and future research is proposed.
Key findings and conclusions
The presence of fluorescent CDs in food produced during food processing has been summarized. Fluorescent CDs less than 10 nm in size mainly contain carbon, oxygen, hydrogen, and/or nitrogen. The presence of CDs in food items was first demonstrated in 2012, and their formation was attributed to heating of the starting material. The properties of CDs in food are different from the engineered nanoparticles used as food as additives and represent a novel kind of nanostructure in food. Further studies should focus on the chronic effects of CDs, although their toxicity is low, because investigations both in vivo and in vitro are limited.
As the food-borne nanoparticles enter the biological system, they will contact with various proteins to form protein coronas, which can affect their physicochemical properties and biological identity. In this study, the protein corona formation of carbon quantum dots (CQDs) from roast salmon with human serum albumin (HSA), as well as biological identity involving cell apoptosis, energy, glucose and lipid metabolism and acute toxicity in mice, were investigated. The HSA-CQD coronas formed between HSA and CQDs via static binding mechanism, and the binding site of CQDs on HSA located both in Sudlow’s site I and site II. The HSA-CQD coronas entered the cytoplasm and present in lysosomes or autolysosomes. Importantly, the HSA coronas mitigated the cytotoxicity of CQDs from 18.65% to 9.26%, and the energy metabolism was rectified from glycolytic to aerobic metabolism. The glucose and lipid metabolite profile of the HSA-CQD coronas differed from that of the CQDs, indicating that HSA-CQD coronas rectified disturbance in metabolism. Histopathological and blood biochemical analysis revealed no statistically significant difference between the testing and control mice after a single CQDs dose of 2000 mg/kg body weight. Overall, the results confirmed the formation of protein corona between HSA and food-borne fluorescent CQDs, and could be helpful for evaluating the safety of fluorescent CQDs from roast food items.
Food-borne nanoparticles (FNs) produced during thermal processing of food may have potential as nanocarriers for Fe(II) supplement. In this paper, the FNs in beef patties at different roasting time (15, 30, 45 minutes) and the binding between FNs and ferrous ions were studied. The size of FNs decreased from 7.5 to 3.0 nm with the increase of baking time, and the FNs emitted bright blue fluorescence under the irradiation of ultra-violet light. The combination of FNs with ferrous ions were by means of functional of amino, hydroxyl and carboxyl groups on the particles. Cell viability study showed that the Fe(II)-FNs increased the apoptotic rate, but significantly decreased the necrosis rate, which led to an increase in the number of living cells. In addition, the Fe(II)-FNs can easily enter Caco-2 cytoplasm, but not the cellular nuclear. The FNs derived from beef patties with ultra-small size, highly water solubility and plenty of functional groups might be good candidates as nanocarriers for Fe(II) delivery.
Foodborne nanoparticles (NPs) refer to the nanostructures generated during food processing, rather than the man-made nano-structural additives that are added to improve the property of food. In this research, discovery of fluorescent NPs in roasted pork was reported at different temperature of 180, 230, and 280 °C. The size of the pork NPs was in the range of 5.93–7.49 nm. The FTIR and XPS analysis showed that the NPs are made up of graphitic carbon (sp2) and carbon defects (sp3), with abundant hydroxyl and carbonyl groups on the surface. The Ussing chamber test clearly showed the pork NPs had permeability passing through intestine. Significant fluorescence quenching of NPs was observed in the digestion in vitro. The bio-distribution of NPs in mice indicated that they obviously presented in liver, kidney and testis, even crossed the blood-brain barrier, entering into the brain. The oral administration of pork NPs at a dose of 2 g/kg mouse body weight did not caused obvious toxicity in BALB/c mice. However, significant influence of the NP exposure was observed on locomotion behaviors and lifespans in wild type Caenorhabditis elegans.
Foodborne nanoparticles produced from food components during thermal processing have received attention due to their particular properties. Herein, the presence of fluorescent carbon dots (CDs) was reported from mackerel flesh roasted at 230 °C in an electronic oven, and the CD capability for free radical scavenging was investigated. The average size of the CDs was about 2.2 nm with a size distribution in the range of 0.9–3.5 nm as characterized with transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) showed that the mackerel CDs mainly contain C, N and O. Fourier transform infrared (FTIR) analysis showed the existence of hydroxyl, amino, and carboxyl groups on the mackerel CD surface. The fluorescence lifetime was about 9.1 ns. Two absorption peaks at 277 and 328 nm were observed in UV–vis spectra, which are assigned to the π-π* and n-π* charge-transfer, respectively. The mackerel CDs showed excellent photostability in various metal ion solutions and pH environment. In addition, these CDs exhibited strong dose-dependent scavenging capability for hydroxyl radicals (·OH) and methyl radicals (·CH 3 ) produced from methylene blue (MB)/visible-light photosensitization system. The free radical scavenging properties make the mackerel CDs capable of protecting against oxidative stress after they are exposed to biosystem.
Carbon dots (CDs)with both one- and two-photon fluorescence have attracted much attention in the field of bioimaging. In this study, we reported a strategy for the design of peptide-conjugated CDs for cellular nuclear-targeted imaging. The CDs were prepared from amino acid and formic acid via an one-step hydrothermal synthesis method, and then modified with trans-activator of transcription (TAT)peptide for both one- and two- photon nuclear-targeted fluorescence imaging. The CDs derived from tryptophan (Trp)and formic acid showed the highest fluorescence quantum yield of 58.4% with an average size about 1.7 nm in diameter. The maximum excitation and emission wavelengths of the Trp/formic acid CDs were 360 and 442 nm, respectively. The Trp/formic acid CDs were successfully conjugated with TAT peptide through the reaction between the amino group of the peptide and carboxylic group of the CDs. Upon grafting with TAT peptide, the resulted TAT-Trp/formic acid CDs could be used as nuclear-targeted fluorescent probes for both one- and two-photon live cell fluorescence imaging.
This study aims to obtain water-soluble fluorescent carbon dots (C-dots) from low-value metabolites through a simple, economical, one-step synthetic route. The urine C-dots (UCDs) and hydrothermally treated urine C-dots (HUCDs) were obtained, respectively, using straightforward Sephadex filtration method from human adults and hydrothermal reaction method. The UCDs and HUCDs emit fluorescence upon being excited with ultraviolet light with a quantum yield of 4.8% and 17.8%, respectively. TEM analysis revealed that UCDs and HUCDs had an average size of 2.5 nm and 5.5 nm, respectively. X-ray photoelectron spectroscopy (XPS) analysis showed the UCDs and HUCDs were mainly composed of carbon, oxygen and nitrogen. Fourier-transform infrared (FTIR) spectroscopy demonstrated the presence of functional groups, such as amino, hydroxyl, carboxylate and carbonyl groups onto the C-dots. The UCDs and HUCDs can be directly used for in vivo and in vitro imaging in Hela cells, Caenorhabditis elegans, onion epidermal cells and bean sprouts. The cytotoxicity study revealed that the UCDs and HUCDs were not toxic to normal rat kidney (NKR) cells with good biocompatibility. The results revealed that the C-dots derived from urine have good biocompatibility, strong fluorescence and may have potential to be a safe fluorescent probe for bio-imaging.
The effect of endogenous carbon nanoparticles from food sources is one of the hot topics in current food research fields. The relationship between the foodborne nanoparticle properties and the cytotoxic mechanism have been insufficiently studied. In this work, carbon dots (CDs) with strong fluorescence were found and purified from canned yellow croaker, and their cytotoxicity was investigated for the first time. The canned yellow croaker CDs are nearly spherical with a particle size distribution in the range of 1.8−5.8 nm. The fluorescence quantum yield of the isolated CDs is 9.7% the maximum excitation wavelength is 340 nm, and with a significant redshift phenomenon in fluorescence spectra. The surface element analysis showed that the composition of the canned yellow croaker CDs was C (76.42%), N (6.49%), O (16.7%), and various functional groups are on the surface. The CDs have good stability in sodium chloride solution and the fluorescence intensity was stable within the pH value of 4 to 10. Strong fluorescence quenching effect was found upon the addition of Cu2 + and Fe3 + to the CD aqueous solution. The CDs can easily enter the interior of the live cells. Moreover, a concentration-dependent behavior of HepG2 cell viability was found when the cells were incubated with the canned yellow croaker CDs. Glycolysis and mitochondrial function analysis of HepG2 cells revealed that both of the extracellular acidification rate and oxygen consumption rate were significantly decreased in contrast to the normal level prior to the addition of CDs. In addition, the CDs significantly inhibited the glycolytic pathway by reducing the activity of key enzyme of hexokinase and pyruvate kinase in glycolytic pathway.
The effective entrapment of Carbon dots (CDs) into a polymer-silica hybrid matrix, formed as free standing transparent flexible films, is presented. CDs of 3 nm mean size with strong photoluminescence are embedded into a silica matrix during the sol-gel procedure, using tetraethylorthosilicate and F127 triblock copolymer as the structure directing agent under acidic conditions. The final hybrid nanostructure forms free standing transparent films that show high flexibility and long term stable CDs luminescence indicating the protective character of the hybrid matrix. It is crucial that the photoluminescence of the hybrid's CDs is not seriously affected after thermal treatment at 550C for 30min. Moreover, the herein reported hybrid is demonstrated to be suitable for the fabrication of advanced photonic structures using soft lithography process due to its low shrinkage and distortion upon drying.
Cellular toxicity test is a key step in assessing the graphene toxicity for its biomedical applications. In this study, we investigated the cytotoxicity of graphene with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and tetrazolium-8-[2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tet-razolium] monosodium salt (CCK-8) assay on HepG2 cell line and Chang liver cell line. The cell viability data obtained by using MTT and CCK-8 assay showed inconsistent. Graphene induced adsorption, optical interferences, as well as electron transfer can prevent to appropriate evaluate graphene toxicity. Our findings demonstrated the importance of careful interpreting of obtained data from classical in vitro assays on assessment of graphene cytotoxicity.
Food nanotechnology is an area of emerging interest and opens up a whole universe of new possibilities for the food industry. The basic categories of nanotechnology applications and functionalities currently in the development of food packaging include: the improvement of plastic materials barriers, the incorporation of active components that can deliver functional attributes beyond those of conventional active packaging, and the sensing and signaling of relevant information. Nano food packaging materials may extend food life, improve food safety, alert consumers that food is contaminated or spoiled, repair tears in packaging, and even release preservatives to extend the life of the food in the package. Nanotechnology applications in the food industry can be utilized to detect bacteria in packaging, or produce stronger flavors and color quality, and safety by increasing the barrier properties. Nanotechnology holds great promise to provide benefits not just within food products but also around food products. In fact, nanotechnology introduces new chances for innovation in the food industry at immense speed, but uncertainty and health concerns are also emerging. EU/WE/global legislation for the regulation of nanotechnology in food are meager. Moreover, current legislation appears unsuitable to nanotechnology specificity.
Photoluminescent carbon dots (C-dots) were prepared using the improved nitric acid oxidation method. The C-dots were characterized by tapping-mode atomic force microscopy, Fourier-transform infrared spectroscopy, and UV--vis absorption spectroscopy. The C-dots were subjected to systematic safety evaluation via acute toxicity, subacute toxicity, and genotoxicity experiments (including mouse bone marrow micronuclear test and Salmonella typhimurium mutagenicity test). The results showed that the C-dots were successfully prepared with good stability, high dispersibility, and water solubility. At all studied C-dot dosages, no significant toxic effect, i.e., no abnormality or lesion, was observed in the organs of the animals. Therefore, the C-dots are non-toxic to mice under any dose and have potential use in fluorescence imaging in vivo, tumor cell tracking, and others.
Shine on you crazy dots: A rapid and high-output strategy for the fabrication of polymer-like carbon dots (CDs) with quantum yields as high as ca. 80 % is presented. This value is the highest reported to date for fluorescent carbon-based materials, and gives promise for their application in multicolor-patterning and biosensors.
A facile, economic and green one-step microwave synthesis route towards photoluminescent carbon dots is proposed. The preparation requires a carbohydrate (glycerol, glycol, glucose, sucrose, etc.) and a tiny amount of an inorganic ion, and can finish in just a few minutes, no surface passivation reagent is needed. The carbon dots are biologically compatible and show favorable optical properties and have potential applications in biolabeling and bioimaging.
Time-resolved fluorescence measurements of graphene oxide in water show multiexponential decay kinetics ranging from 1 ps to 2 ns. Electron-hole recombination from the bottom of the conduction band and nearby localized states to wide-range valance band is suggested as origin of the fluorescence. Excitation wavelength dependence of the fluorescence was caused by relative intensity changes of few emission species. By introducing the molecular orbital concept, the dominant fluorescence was found to originate from the electronic transitions among/between the non-oxidized carbon regions and the boundary of oxidized carbon atom regions, where all three kinds of functionalized groups C-O, C = O and O = C-OH were participating. In the visible spectral range, the ultrafast fluorescence of graphene oxide was observed for the first time.
We report the finding of the presence of carbon nanoparticles (CNPs) in different carbohydrate based food caramels, viz. bread, jaggery, sugar caramel, corn flakes and biscuits, where the preparation involves heating of the starting material. The CNPs were amorphous in nature; the particles were spherical having sizes in the range of 4-30 nm, depending upon the source of extraction. The results also indicated that particles formed at higher temperature were smaller than those formed at lower temperature. Excitation tuneable photoluminescence was observed for all the samples with quantum yield (QY) 1.2, 0.55 and 0.63%, for CNPs from bread, jaggery and sugar caramels respectively. The present discovery suggests potential usefulness of CNPs for various biological applications, as the sources of extraction are regular food items, some of which have been consumed by humans for centuries, and thus they can be considered as safe.
Nanotechnology is developing rapidly and, in the future, it is expected that increasingly more products will contain some sort of nanomaterial. However, to date, little is known about the occurrence, fate and toxicity of nanoparticles. The limitations in our knowledge are partly due to the lack of methodology for the detection and characterisation of engineered nanoparticles in complex matrices, i.e. water, soil or food. This review provides an overview of the characteristics of nanoparticles that could affect their behaviour and toxicity, as well as techniques available for their determination. Important properties include size, shape, surface properties, aggregation state, solubility, structure and chemical composition. Methods have been developed for natural or engineered nanomaterials in simple matrices, which could be optimized to provide the necessary information, including microscopy, chromatography, spectroscopy, centrifugation, as well as filtration and related techniques. A combination of these is often required. A number of challenges will arise when analysing environmental and food materials, including extraction challenges, the presence of analytical artifacts caused by sample preparation, problems of distinction between natural and engineered nanoparticles and lack of reference materials. Future work should focus on addressing these challenges.
We report the finding of the presence of fluorescent carbon dots in commercial beer and TEM analysis reveals that the beer carbon dots (BCDs) have an average size of 2.5 nm. The BCDs possessed high solubility and excellent fluorescence properties under the excitation of ultra-violet light with a quantum yield of approximately 7.39%. X-ray photoelectron spectroscopy (XPS) characterization demonstrated that the BCDs contain carbon, oxygen and nitrogen, three elements with the relative contents ca. 59.52%, 36.71% and 3.77%, respectively. X-ray diffraction (XRD) analysis indicated that the BCDs are amorphous. Fourier transform infrared (FTIR) spectroscopy was employed to characterize the surface groups of the BCDs. The BCDs showed excellent stability under different conditions (high ion strength, extreme pH and laser exposure). The cytotoxicity study revealed that there was no obvious inhibition of cell viability with a concentration as high as 12.5 mg mL−1 for 48 h, so that the BCDs could be directly applied in live cell imaging. Moreover, the BCDs could be used as efficient nanocarriers for the purpose of anticancer therapy. Doxorubicin-conjugated BCDs (BCD-DOX) induced prolonged cytotoxicity compared to free doxorubicin (DOX) due to the slow release of DOX from the BCD-DOX. The internalization of BCD-DOX by MCF-7 cells was further confirmed by using a laser scanning confocal microscope. All these results indicated that the BCDs present in beer have good biocompatibility and excellent fluorescence properties and may be considered as a safe material for bio-imaging and image-guided drug delivery in cancer therapy.
The presence of nanoparticles in beverages has raised great concern in terms of potential impacts to consumer health. Herein, carbon dots in beverages Kvass, Pony Malta, Pilsner beer, Vivant Storm, and Profit were identified. They were shown to have strong fluorescence under the excitation of ultra-violet light. The emission peaks shift to longer wavelengths accompanied by a remarkable fluorescence intensity decrease. The carbon dots are in the nanosized range and roughly spherical in appearance. Elemental analysis by X-ray photoelectron spectroscopy demonstrated the composition of Kvass carbon dots to be C 83.17%, O 13.83% and N 3.00%, respectively. No cytotoxicity was found at concentrations up to 20 mg/mL for human tongue squamous carcinoma cells, and they can be directly applied in both carcinoma and onion epidermal cell imaging. This work represents the first report of the carbon dots present in beverages, providing valuable insights into these nanoparticles for future biological imaging.
The synthesis of water-soluble fluorescent carbon dots (C-dots) has received much attention recently. Here, high quality fluorescent C-dots have been synthesized through low-temperature carbonization and simple filtration using watermelon peel, a waste and reproducible raw resource, as a novel carbon resource. This facile approach allows large-scale production of aqueous C-dots dispersions without any post-treatment process. The as-prepared C-dots possess small particle sizes (~ 2.0 nm), strong blue luminescence, acceptable fluorescence lifetime and good stability in a wide range of pH values (pH 2.0–11.0) and at a high salt concentration. Besides, the obtained C-dots have been successfully applied in live cell imaging, indicating these carbon nanoparticles can serve as high-performance optical imaging probes.
Carbon dots (C-dots) are a class of novel fluorescent nanomaterials, which have drawn great attention for their potential applications in bio-nanotechnology. Multicolor C-dots have been synthesized by chemical nitric acid oxidation using the reproducible plant soot as raw material. TEM analysis reveals that the prepared C-dots have an average size of 3.1nm. The C-dots are well dispersed in aqueous solution and are strongly fluorescent under the irradiation of ultra-violet light. X-ray photoelectron spectroscopy characterization demonstrates that the O/C atomic ratio for C-dots change to from 0.207 to 0.436 due to the chemical oxidation process. The photo bleaching experiment reveals that the C-dots show excellent photostability as compared with the conventional organic dyes, fluorescein and rhodamine B. The fluorescence intensity of the C-dots did not change significantly in the pH range of 3-10. To further enhance the fluorescence quantum yield, the C-dots were surface modified with four types of passivation ligands, 4,7,10-trioxa-1,13-tridecanediamine (TTDDA), poly-L-lysine (PLL), cysteine and chitosan and the fluorescence quantum yields of the TTDDA, PLL, cysteine and chitosan passivated C-dots were improved 1.53-, 5.94-, 2.00- and 3.68-fold, respectively. Fourier-transform infrared (FTIR) spectra were employed to characterize the surface groups of the C-dots. The bio-application of the C-dots as fluorescent bio-probes was evaluated in cell imaging and ex vivo fish imaging, which suggests that the C-dots may have potential applications in biolabeling and bioimaging.
Graphene oxide (GO) has been extensively explored in nanomedicine for its excellent physiochemical, electrical, and optical properties. Here, polyethylene glycol (PEG) and polyethylenimine (PEI) are covalently conjugated to GO via amide bonds, obtaining a physiologically stable dual-polymer-functionalized nano-GO conjugate (NGO-PEG-PEI) with ultra-small size. Compared with free PEI and the GO-PEI conjugate without PEGylation, NGO-PEG-PEI shows superior gene transfection efficiency without serum interference, as well as reduced cytotoxicity. Utilizing the NIR optical absorbance of NGO, the cellular uptake of NGO-PEG-PEI is shown to be enhanced under a low power NIR laser irradiation, owing to the mild photothermal heating that increases the cell membrane permeability without significantly damaging cells. As the results, remarkably enhanced plasmid DNA transfection efficiencies induced by the NIR laser are achieved using NGO-PEG-PEI as the light-responsive gene carrier. More importantly, it is shown that our NGO-PEG-PEI is able to deliver small interfering RNA (siRNA) into cells under the control of NIR light, resulting in obvious down-regulation of the target gene, Polo-like kinase 1 (Plk1), in the presence of laser irradiation. This study is the first to use photothermally enhanced intracellular trafficking of nanocarriers for light-controllable gene delivery. This work also encourages further explorations of functionalized nano-GO as a photocontrollable nanovector for combined photothermal and gene therapies.
In the last three decades, zero-dimensional, one-dimensional, and two-dimensional carbon nanomaterials (i.e., fullerenes, carbon nanotubes, and graphene, respectively) have attracted significant attention from the scientific community due to their unique electronic, optical, thermal, mechanical, and chemical properties. While early work showed that these properties could enable high performance in selected applications, issues surrounding structural inhomogeneity and imprecise assembly have impeded robust and reliable implementation of carbon nanomaterials in widespread technologies. However, with recent advances in synthesis, sorting, and assembly techniques, carbon nanomaterials are experiencing renewed interest as the basis of numerous scalable technologies. Here, we present an extensive review of carbon nanomaterials in electronic, optoelectronic, photovoltaic, and sensing devices with a particular focus on the latest examples based on the highest purity samples. Specific attention is devoted to each class of carbon nanomaterial, thereby allowing comparative analysis of the suitability of fullerenes, carbon nanotubes, and graphene for each application area. In this manner, this article will provide guidance to future application developers and also articulate the remaining research challenges confronting this field.
Nanotechnology has expanded its wings in various spheres of life. It has progressed from first-generation passive nanomaterial to active nanotechnology (e.g., drug delivery) and nanosystems (e.g., robotics). Although nanofood is still in its infancy; however, these particles are now finding application as a carrier of antimicrobial polypeptides required against microbial deterioration of food quality in the food industry. Another challenging area is nanoencapsulation of pesticides that releases the pesticides within the stomach of the insect, thus minimizing contamination of crops and vegetables. The current nanotechnology applications in food science provide the detection of food pathogens, through nanosensors, which are quick, sensitive and less labour-intensive procedures. With the increasing health consciousness among consumers, it is possible to use nanosensors in plastic packaging to detect gases released due to food spoilage. However, it is well known that the nanoparticles equipped with new chemical and physical properties that vary from normal macro particles of the same composition may interact with the living systems thereby causing unexpected toxicity. Limited toxicological/safety assessments have been carried out for a few nanoparticles; hence studies relevant to oral exposure risk assessment are required for particles to be used in food.
The presence, dissolution, agglomeration state, and release of materials in the nano-size range from food containing engineered nanoparticles during human digestion is a key question for the safety assessment of these materials. We used an in vitro model to mimic the human digestion. Food products subjected to in vitro digestion included (i) hot water, (ii) coffee with powdered creamer, (iii) instant soup, and (iv) pancake which either contained silica as the food additive E551, or to which a form of synthetic amorphous silica or 32 nm SiO(2) particles were added. The results showed that, in the mouth stage of the digestion, nano-sized silica particles with a size range of 5-50 and 50-500 nm were present in food products containing E551 or added synthetic amorphous silica. However, during the successive gastric digestion stage, this nano-sized silica was no longer present for the food matrices coffee and instant soup, while low amounts were found for pancakes. Additional experiments showed that the absence of nano-sized silica in the gastric stage can be contributed to an effect of low pH combined with high electrolyte concentrations in the gastric digestion stage. Large silica agglomerates are formed under these conditions as determined by DLS and SEM experiments and explained theoretically by the extended DLVO theory. Importantly, in the subsequent intestinal digestion stage, the nano-sized silica particles reappeared again, even in amounts higher than in the saliva (mouth) digestion stage. These findings suggest that, upon consumption of foods containing E551, the gut epithelium is most likely exposed to nano-sized silica.
Oxidization of carbon nanotubes by a mixed acid has been utilized as a standard method to functionalize carbon nanomaterials for years. Here, the products obtained from carbon nanotubes and graphite after a mixed-acid treatment are carefully studied. Nearly identical carbon dot (Cdot) products with diameters of 3-4 nm are produced using this approach from a variety of carbon starting materials, including single-walled carbon nanotubes, multiwalled carbon nanotubes, and graphite. These Cdots exhibit strong yellow fluorescence under UV irradiation and shifted emission peaks as the excitation wavelength is changed. In vivo fluorescence imaging with Cdots is then demonstrated in mouse experiments, by using varied excitation wavelengths including some in the near-infrared (NIR) region. Furthermore, in vivo biodistribution and toxicology of those Cdots in mice over different periods of time are studied; no noticeable signs of toxicity for Cdots to the treated animals are discovered. This work provides a facile method to synthesize Cdots as safe non-heavy-metal-containing fluorescent nanoprobes, promising for applications in biomedical imaging.
Nanotechnology derived products are now used in various spheres of life including food industry. Indeed nanotechnology may transform entire food industry in terms of production, processing and packaging and consumption. Due to their small size, nanoparticles find application as a carrier of antimicrobial polypeptides required against microbial deterioration of food quality. Detection of food pathogens, fungus producing mycotoxins, viruses and bacteria through nanosensors, which are quick, sensitive and less labour intensive procedures, is another area having potential application. The use of nanosensors in plastic packaging to detect gases released due to food spoilage is of consumer's relevance. Majority of nanoparticles for food use are organic moieties, hence it is of utmost importance to investigate their physico-chemical characteristics followed by toxicological implications to intestinal cells. It remains to be seen that nanostructured ingredients and nutrient delivery system may also carry other foreign substances to blood. Nano sized particles for food usage, having new chemical and physical properties may vary from normal macro particles that may also influence the interaction with living systems. Hence in vitro and in vivo studies are required for nanoparticles to be used in foods prior to their commercialization.
Using commercially activated carbon, we developed a simple and effective direct chemical oxidation route to prepare good biocompatible multicolor photoluminescent carbon dots.
Carbon nanoparticles become photoluminescent upon surface passivation with oligomeric polymer chains. In this work, the dependence of the carbon dots photoluminescent properties on the passivation polymer selection has been demonstrated by conjugating polyethylene glycol (PEG) chains, polyethylenimide-co-polyethylene glycol-co-polyethylenimide copolymer, and 4-armed PEG molecules, respectively. The cytotoxicity and cellular internalization of the resulting three types of photoluminescent nanoformulations of carbon dots, named CD2, CD3, and CD4, were evaluated. These nanoformulations exhibited no apparent cytotoxicity on their own and were shown to successfully target cancer cells by conjugation with transferrin. The implication to the use of carbon dots as biocompatible optical nanoprobes for in vitro cancer diagnostics is discussed.
(Figure Presented) Size control: A one-step alkali metalassisted electrochemical method for the fabrication of carbon quantum dots (CQDs) with size-dependent photoluminescence is presented (see picture). Their upconversion luminescence may provide a way for the development of novel photocatalysts.
Application of bionanotechnologies and synthetic nanoparticles in agriculture and food production offer opportunities for both the food industry and consumers. Nanotechnologies are used in novel pesticide formulations, in packaging materials to increase barrier properties, in contamination detection systems, in increasing nutritional value of foods and its interaction with body's digestive and metabolic processes. Different classes of nanoparticles are applied: nanoscale metals (gold, titanium dioxide), nanofibers, nanocapsules (encapsulation of bio-active compounds). It is the type of particle and the type of application that determine its benefits and risks to the consumer. Currently knowledge on risks of nanotechnologies to the consumer is starting to be collected. Much more is known on potential hazards of these technologies. In the current project the reliability of the safety assessment was studied. All steps in the risk assessment paradigm for nanotechnologies were evaluated compared to that of normal chemicals. What are the physiochemical and biological effects of the small size of the chemicals on analytical requirements for isolation and characterisation methods, bioavailability and other kinetic studies, tests for local and systemic toxicity and the food legislative system. This review of state-of-the-knowledge of safety assessment of nanoparticles and nanotechnologies in food will result in a priority list of research needs. Concrete projects will be formulated aiming to increase the reliability of the risk assessment within a few years.
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