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3D fluorescence spectra (excitation (y-scale), emission (x-scale) and intensity (false colour scale)) of CATris (left) and CAArg (right).
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Bioimaging supported by nanoparticles requires low cost, highly emissive and photostable systems with low cytotoxicity. Carbon dots (C-dots) offer a possible solution, even if controlling their properties is not always straightforward, not to mention their potentially simple synthesis and the fact that they do not exhibit long-term photostability i...
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... particular, arginine provides both carboxyl and amino groups that form the amide linkage at high temperatures [20] and, in turn, causes the appearance of low energy UV absorption bands in nitrogen rich C-dots. Figure 3 shows the 3D fluorescence spectra (excitation (y-scale), emission (x-scale) and intensity (false colour scale)) of CATris and CAArg. Under excitation at 343 nm, CATris exhibits an emission peaking at 415 nm in the blue range. ...
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... changes in intensity are due to the different C-dot responses when excited with a λ ex = 400 nm. At this wavelength, in fact, the intensity of the blue emission is weak for both CATris and CAarg (Figure 3), while the intensity of emission at a longer wavelength is higher. The images have been separated according to the green, blue and red channels for a better understanding. ...
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... images obtained by changing the concentration do not show significant differences; therefore, increasing the CATris concentration from 1 to 3 mg mL −1 does not result in an effective increase in fluorescence and uptake from the cells. The lower brightness of some images (Figure 8, row 3) is due to the inhomogeneity of the cell culture and the local distribution of carbon dots and cannot be related to the higher concentration of C dots. The concentration of 1 mg mL −1 of CATris represents an efficient threshold level for cell labeling. ...
Citations
... These results confirm the long-term stability and robustness of the ME-CDs. The exceptional stability and strong fluorescence of the hydrothermally synthesized ME-CDs make them highly effective for biocellular imaging [61]. Further, the presence of hydrophilic functional groups such as -COOH, -OH, and -NH, confirmed through FTIR and XPS analyses, showed good dispersibility in aqueous environments and compatibility with biological systems. ...
... The combination of intense and environment-sensitive PL of nanoparticles, biocompatibility, non-toxicity, and hydrophilic/hydrophobic surface allows the use of CD not only for the analysis of technological environments [7,8], but also for solving various biomedical problems, such as pH measurement [13,14], visualization [10,11,15,16], temperature monitoring [10], and composition diagnostics [11] of biological tissues. The authors of the publication [11] used CD to visualize E. coli and Staphylococcus aureus in biological tissue. ...
The effective use of polymer carbon dots (PCD) in various fields of science and technology requires a more detailed understanding of the mechanisms of their photoluminescence formation and change as a result of their interaction with the environment. In this study, PCD synthesized via a hydrothermal method from citric acid and ethylenediamine are studied in various solvents using FTIR spectroscopy, optical absorption spectroscopy, and photoluminescence spectroscopy. As a result of the analysis of the obtained dependencies of such PCD spectral characteristics as the photoluminescence FWHM, the photoluminescence quantum yield, the photoluminescence lifetime on the acidity and basicity of the solvent, a hypothesis was formulated on the formation mechanism of hydrogen bonds between the PCD surface groups and the molecules of the environment, and conclusions were made about the donor–acceptor nature of the synthesized PCD.
... It can be challenging to regulate the optical characteristics of CDs made from citric acid, resulting in changes in their fluorescence and quantum yields [25]. Citric acid-synthesized CDs might also lack long-term photostability, which is crucial for bioimaging applications [26]. ...
Carbon dots (CDs) derived from mandarin peel biochar (MBC) at different pyrolysis temperatures (200, 400, 600, and 800 °C) have been synthesized and characterized. This high-value transformation of waste materials into fluorescent nanoprobes for environmental monitoring represents a step forward towards a circular economy. In this itinerary, CDs produced via one-pot hydrothermal synthesis were utilized for the detection of copper (II) ions. The study looked at the spectroscopic features of biochar-derived CDs. The selectivity of CDs obtained from biochar following carbonization at 400 °C (MBC400-CDs towards various heavy metal ions resulted in considerable fluorescence quenching with copper (II) ions, showcasing their potential as selective detectors. Transmission electron microscopic (TEM) analysis validated the MBC-CDs’ consistent spherical shape, with a particle size of <3 nm. The Plackett–Burman Design (PBD) was used to study three elements that influence the F0/F ratio, with the best ratio obtained with a pH of 10, for 10 min, and an aqueous reaction medium. Cu (II) was detected over a dynamic range of 4.9–197.5 μM and limit of detection (LOD) of 0.01 μM. Validation testing proved the accuracy and precision for evaluating tap and mountain waters with great selectivity and no interference from coexisting metal ions.
... The samples, which consisted of aqueous solutions containing solely carbon dots, were positioned in front of the UV light within a dimly lit chamber for a duration spanning several hours. Subsequently, the fluorescence intensities were recorded at various time intervals [34]. ...
... The quantum yield of CD nanoparticles was determined to be 20.1 % based on the study conducted by Williams et al. [17,35],which investigated the excitation and emission properties of these nanoparticles. The photostability of luminescent nanomaterials is crucial for assessing their applications, especially in C-dots as potential fluorescent probes for cell and tissue imaging, considering fluorescence emission intensity during continuous excitation [34]. The fluorescence intensity of CDs maintained 65 % of their initial emission intensity after 6 h of UV light exposure (Fig. 3C). ...
... Notably, the exceptional optical properties and high specific surface area of CDs allow for surface physical and chemical modifications, further enhancing their functionality in biomedical applications [14][15][16][17][18]. A highly efficient protocol has recently been developed to yield decagram-scale quantities of N,S-doped CDs featuring a narrow size distribution and bright emission. ...
In this study, we introduce novel microporous poly(D,L-lactide) acid-carbon nanodot (PLA-CD) nanocomposite scaffolds tailored for potential applications in image-guided bone regen-eration. Our primary objective was to investigate concentration-dependent structural variations and their relevance to cell growth, crucial aspects in bone regeneration. The methods employed included comprehensive characterization techniques such as DSC/TGA, FTIR, rheological, and degradation assessments, providing insights into the scaffolds' thermoplastic behavior, microstruc-ture, and stability over time. Notably, the PLA-CD scaffolds exhibited distinct self-fluorescence, which persisted after 21 days of incubation, allowing detailed visualization in various multicolor modalities. Biocompatibility assessments were conducted by analyzing human adipose-derived stem cell (hADSC) growth on PLA-CD scaffolds, with results substantiated through cell viability and morphological analyses. hADSCs reached a cell viability of 125% and penetrated throughout the scaffold after 21 days of incubation. These findings underscore the scaffolds' potential in bone regeneration and fluorescence imaging. The multifunctional nature of the PLA-CD nanocomposite, integrating diagnostic capabilities with tunable properties, positions it as a promising candidate for advancing bone tissue engineering. Our study not only highlights key aspects of the investigation but also underscores the scaffolds' specific application in bone regeneration, providing a foundation for further research and optimization in this critical biomedical field.
... We found that Mt-GQDs were detected in both the TRITC and FITC channels, making it challenging to use a differential dye for validation of results (Supplementary Figure, Fig. S2). Several studies have also demonstrated a wide range of fluorescence detection of quantum dots prepared from citric acid and glutamic acid, which allows imaging in red, blue and green channels [41,42]. This limitation indicates that further investigations are warranted to validate the presence of mitochondria and GQDS in MtGQDs through both in vitro and in vivo imaging. ...
Mitochondria transplantation has emerged as a successful therapeutic modality to treat several degenerative diseases. However, the biodistribution of transplanted mitochondria has not been well studied. We investigated the ex-vivo systemic biodistribution and therapeutic efficacy of intravenously transplanted graphene quantum dots (GQDs) conjugated to isolated mitochondria (Mt-GQDs) in diabetic rat tissues. The results revealed that Mt-GQDs facilitate the tracking of transplanted mitochondria without affecting their therapeutic efficacy. It is compelling to note that Mt-GQDs and isolated mitochondria show comparable therapeutic efficacies in decreasing blood glucose levels, oxidative stress, inflammatory gene expressions, and restoration of different mitochondrial functions in pancreatic tissues of diabetic rats. In addition, histological section examination under a fluorescence microscope demonstrated the localization of Mt-GQDs in multiple tissues of diabetic rats. In conclusion, this study indicates that Mt-GQDs provide an effective mitochondrial transplantation tracking modality.
... The combination of nanocomposites and FRET enables synergistic action to accelerate the mechanical activation of mechanophores. On the other hand, carbon dot (CD) nanoparticles, which are generally used as bactericide [43][44][45][46], bioimaging [47][48][49], photocatalyst [50,51], can also be potentially used to improve fluorescent intensity of polymer materials based on FRET mechanism [52][53][54][55]. Accordingly, embedding CD nanoparticles not only can reinforce the mechanical properties of polymer nanocomposites as nanofillers, but also can tailor the fluorescence of materials as energy donor in FRET, leading to synergistic enhancement of mechanoresponsiveness of polymer materials. ...
Mechanochromism in polymers has attracted great interests in recent years. Herein, we develop a mechanochromic elastomer carrying spiropyran mechanophores in the chain and mechanoresponsiveness of elastomer is enhanced by embedding luminescent carbon dot (CD) nanoparticles as crosslinkers and energy donor in fluorescence resonance energy transfer (FRET). Compared with the control with physically blended CD, CD crosslinked elastomer exhibit excellent daylight and fluorescent colors change under stretching. The mechanochemically induced fluorescence change is a result of FRET between CD nanoparticles and the activated merocyanine. The control with physically blended CD nanoparticles shows low FRET in stretching due to lower fraction of spiropyran activation as a result of lower mechanical properties. Furthermore, the CD crosslinked elastomer has already been applied in rewritable mechanochemical and photochemical recording or printing. Our demonstration shows that interfacial chemical bonding plays a critical role in the reinforcement of mechanical properties for polymer composites and may exhibit great potential in the study of the acceleration of mechanoresponsiveness of polymer and multi-responsiveness of polymer nanocomposites.
The development of bioactive materials with controllable preparation is of great significance for biomedical engineering. Citric acid-based biomaterials are one of the few bioactive materials with many advantages such as simple synthesis, controllable structure, biocompatibility, biomimetic viscoelastic mechanical behavior, controllable biodegradability, and further functionalization. In this paper, we review the development of multifunctional citrate-based biomaterials for biomedical applications, and summarize their multifunctional properties in terms of physical, chemical, and biological aspects, and finally the applications of citrate-based biomaterials in biomedical engineering, including bone tissue engineering, skin tissue engineering, drug/cell delivery, vascular and neural tissue engineering, and bioimaging.
Advances in nanotechnology and nanomaterials have attracted considerable interest and play key roles in scientific innovations in diverse fields. In particular, increased attention has been focused on carbon-based nanomaterials exhibiting diverse extended structures and unique properties. Among these materials, zero-dimensional structures, including fullerenes, carbon nano-onions, carbon nanodiamonds, and carbon dots, possess excellent bioaffinities and superior fluorescence properties that make these structures suitable for application to environmental and biological sensing, imaging, and therapeutics. This review provides a systematic overview of the classification and structural properties, design principles and preparation methods, and optical properties and sensing applications of zero-dimensional carbon nanomaterials. Recent interesting breakthroughs in the sensitive and selective sensing and imaging of heavy metal pollutants, hazardous substances, and bioactive molecules as well as applications in information encryption, super-resolution and photoacoustic imaging, and phototherapy and nanomedicine delivery are the main focus of this review. Finally, future challenges and prospects of these materials are highlighted and envisaged. This review presents a comprehensive basis and directions for designing, developing, and applying fascinating fluorescent sensors fabricated based on zero-dimensional carbon nanomaterials for specific requirements in numerous research fields.
The bone-targeting mechanism of clinic bisphosphonate-type drugs, such as alendronate, risedronate, and ibandronate, relies on chelated calcium ions on the surface of the bone mineralized matrix for the treatment of osteoporosis. EGTA with aminocarboxyl chelating ligands can specifically chelate calcium ions. Inspired by the bone-targeting mechanism of bisphosphonates, we hypothesize that EGTA-derived carbon dots (EGTA-CDs) hold bone-targeting ability. For the target-oriented synthesis of EGTA-CDs and to endow CDs with bone targeting, we designed calcium ion chelating agents as precursors, including aminocarboxyl chelating agents (EGTA and EDTA) and bisphosphonate agents (ALN and HEDP) for the target-oriented synthesis of aminocarboxyl-derived CDs (EGTA-CDs and EDTA-CDs) and bisphosphonate-derived CDs (ALN-CDs and HEDP-CDs) with high synthetic yield. The synthetic yield of EGTA-CDs reached 87.6%. Aminocarboxyl-derived CDs and bisphosphonate-derived CDs retain the chelation ability of calcium ions and can specifically bind calcium ions. The chemical environment bone-targeting value coordination constant K and chelation sites of EGTA-CDs were 6.48 × 104 M-1 and 4.12, respectively. A novel method was established to demonstrate the bone-targeting capability of chelate-functionalized carbon dots using fluorescence quenching in a simulated bone trauma microenvironment. EGTA-CDs exhibit superior bone-targeting ability compared with other aminocarboxyl-derived CDs and bisphosphonate-derived CDs. EGTA-CDs display exceptional specificity toward calcium ions and better bone affinity than ALN-CDs, suggesting their potential as novel bone-targeting drugs. EGTA-CDs with strong calcium ion chelating ability have calcium ion affinity in simulated body fluid and bone-targeting ability in a simulated bone trauma microenvironment. These findings offer new avenues for the development of advanced bone-targeting strategies.
