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Water-soluble acetylated chitosan-stabilized gold nanosphere bioprobes

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Abstract

Sustainable biopolymers are intriguing motifs for transferring the distinct biocompatibility and recognition into inorganic nanoparticles, which have a potential to be used in biomedicine applications. Here we report scalable production of water-soluble chitosan polymers from N-acetylation. One-pot aqueous synthesis of water-dispersible gold nanospheres is developed using the acetylated chitosan as a stabilizer and a reducing agent. The inherent aqueous solubility of the acetylated chitosan renders the gold nanospheres dispersible in water and enables for controlling the uniform size and monodispersity. The acetylated chitosan-stabilized gold nanospheres with plasmonic and biocompatible properties are used as efficient bioprobes for the selective detection of various biochemical agents of melamine, bacteria, and uric acid.

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... Water-soluble chitosan polymers produced from N-acetylation. The acetylated chitosan-stabilized gold nanospheres are recommended as bioprobes to detect selectively various biochemical agents of melamine, bacteria, and uric acid [81]. ...
... Tiếp tục Đối với các hợp chất hữu cơ, hầu hết phản ứng diễn ra đều chậm. Lành và các cộng sự[11], tổng hợp AuNP đã sử dụng chitosan vừa là chất khử vừa là chất bảo vệ, quá trình phản ứng đã diễn ra trong suốt 8 giờ. Ở bài báo này, chúng tôi sử dụng dextran để điều chế AuNP ở nhiệt độ phòng trong môi trường pH = 12, nồng độ Au 3+ và dextran lần lượt là 0,50 mM và 1,0 %. ...
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Tóm tắt – Hạt nano vàng (AuNPs) hình cầu, có kích thước khoảng 6-15 nm được tổng hợp bằng phương pháp khử hóa học, với dextran là chất ổn định. Máy khuấy từ được dùng để trộn hỗn hợp dung dịch axit tetrachloroauric và dextran ở nhiệt độ phòng. Ảnh hưởng của thời gian khử, nồng độ Au3+ và nồng độ dextran đến kích thước của AuNPs đã được khảo sát. Vi cấu trúc của AuNPs được đặc trưng bởi phổ UV-Vis, phương pháp nhiễu xạ tia X (XRD) và kính hiển vi điện tử truyền qua (TEM). Kết quả cho thấy, AuNPs có kích thước nhỏ, độ đồng nhất cao được tổng hợp ở nhiệt độ phòng, nồng độ Au3+ là 0,50 mM, dextran là 1,0 % và pH = 12. Khi dung dịch Au3+ ở nồng độ thấp, sản phẩm là AuNPs có kích thước nhỏ nhưng ngược lại, khi dextran ở nồng độ thấp, sản phẩm thu được là AuNPs có kích thước lớn. Bột AuNPs thu được bằng phương pháp sấy phun. Độ tinh khiết của bột AuNPs được kiểm tra bằng phổ tán sắc năng lượng tia X (EDX). AuNPs dạng dung dịch hoặc dạng bột được ổn định bởi dextran - chất tương thích sinh học, đã có nhiều ứng dụng tiềm năng trong y sinh học và dược phẩm. Từ khóa - Hạt nano vàng, Dextran, Phương pháp hóa học.
... This method showed a LOD at picogram level, and hence such design is highly desirable. The BSA conjugated Au NPs were Aggregation and electrostatic forces involved tactics were also described by a few reports [122,134,144,154,158]. However, these methodologies still require more attention. ...
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In this study, we demonstrate a more sensitive colorimetric assay for the detection of melamine based on the strong attraction between exocyclic amine groups of melamine and surface-bound AuCl(4)(-)/AuCl(2)(-) ions on bare gold nanoparticles prepared by the borohydride reduction method. This method is rather simple without further modification of gold nanoparticles and complicated pretreatment of samples. The detection limit of the method is 2.0 × 10(-7) g L(-1) for melamine in infant formula, which is much lower (about 1000-fold) than that of using citrate-capped GNPs as a colorimetric probe. The proposed scheme could be a good alternative means for on-site and real-time screening of melamine adulterant in infant formula without costly instruments.
Article
Gold nanorods with aspect ratios of 4.6 ± 1.2, 13 ± 2, and 18 ± 2.5 (all with 16 ± 3 nm short axis) are prepared by a seeding growth approach in the presence of an aqueous miceller template. Citrate-capped 3.5 nm diameter gold particles, prepared by the reduction of HAuCl4 with borohydride, are used as the seed. The aspect ratio of the nanorods is controlled by varying the ratio of seed to metal salt. The long rods are isolated from spherical particles by centrifugation.
Article
Noble metal nanoparticles are capable of confining resonant photons in such a manner as to induce coherent surface plasmon oscillation of their con- duction band electrons, a phenomenon leading to two important properties. Firstly, the confinement of the photon to the nanoparticle's dimensions leads to a large increase in its electromagnetic field and consequently great enhancement ofall the nanoparticle's radiative properties, such as absorption and scattering. Moreover, by confining the photon's wavelength to the nanoparticle's small dimensions, there exists enhanced imaging resolving powers, which extend well below the diffraction limit, a property of con- siderable importance in potential device applications. Secondly, the strongly absorbed light by the nanoparticles is followed by a rapid dephasing of the coherent electron motion in tandem with an equally rapid energy transfer to the lattice, a process integral to the technologically relevant photothermal properties of plasmonic nanoparticles. Of all the possible nanoparticle shapes, gold nanorods are especially intriguing as they offer strong plasmonic fields while exhibiting excellent tunability and biocompatibility. We begin this review of gold nanorods by summarizing their radiative and nonradiative properties. Their various synthetic methods are then outlined with an emphasis on the seed-mediated chemical growth. In particular, we describe nanorod spontaneous self-assembly, chemically driven assembly, and poly- mer-based alignment. The final section details current studies aimed at applications in the biological and biomedical fields.
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Gold-chitosan nanocomposite is successfully proposed for assembling a sensitive and selective electrochemical sensor for the determination of an antioxidant such as caffeic acid, which has recently attracted much attention due to its benefits on human health. In this paper, taking advantage of the peculiar sensing performance of the nanocomposite, an analytical method based on differential pulse voltammetry for determination of polyphenols index in wines was proposed
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Metal nanocrystals with concave surfaces are interesting for a wide variety of applications that are related to catalysis, plasmonics, and surface-enhanced spectroscopy. This interest arises from their high-index facets, surface cavities, and sharp corners/edges. Two major challenges are associated with this novel class of nanocrystals: 1) how to generate a concave surface with negative curvature, which is not favored by thermodynamics owing to its higher energy than the convex counterpart; and 2) how to stabilize the morphology of a nanocrystal with concave structures on the surface. Recently, a number of different procedures have been developed for the synthesis of noble-metal nanocrystals with concave surfaces. This Review provides a brief account of these developments, with the aim of offering new insights into the growth mechanisms. We focus on methods based on two general strategies: 1) site-specific dissolution through etching and galvanic replacement; and 2) directionally controlled overgrowth by facet-selective capping, kinetic control, and template-directed epitaxy. Their enhanced catalytic and electrocatalytic properties are also described.
Article
Chitin nanofibers of 10–20 nm width and high aspect ratio were prepared using a series of chemical treatments followed by mechanical grinding treatment from exoskeletons of crabs and prawns and cell wall of mushrooms. The nanofibers obtained are uniform and have both linear and network structures. Mechanical treatment under acidic (pH 3–4) conditions facilitated nano-fibrillation. The cationization of amino groups on the fiber surface of chitin improved fibrillation by electrostatic repulsion. Nanofiber surface was modified by acetylation for increasing applications of nanofibers. The sheet of neat chitin nanofibers was opaque; however, it became transparent by blending nanofibers with different types of acrylic resins due to nano-sized structure of fibers. Young’s moduli and the tensile strengths increased significantly, while thermal expansion of acrylic resins decreased as a result of reinforcement of resins with chitin nanofibers. Chitin nanofiber showed chiral separation ability as well. Chitin nanofiber membrane transported the D-isomer of glutamic acid, phenylalanine, and lysine from the corresponding racemic amino acid mixtures faster than L-isomer. From the viewpoint of medical applications, chitin nanofibers improved clinical symptoms and suppressed ulcerative colitis in dextran sulfate sodium-induced mouse model of acute ulcerative colitis.
Article
Despite the modern treatment processes, contamination of food, water and medical equipment by pathogenic bacteria is very common in this world. Since the last two decades, one of the most important and complex problems our society has been facing is that several human pathogens became resistant to most of the clinically approved antibiotics. Recent advancement in nanoscience and nanotechnology has expanded our ability to design and construct nanomaterials with targeting, therapeutic, and diagnostic functions. These multifunctional materials have attracted our attention to be used as the promising tool for selective bacteria sensing and therapy without the current drugs. This tutorial review provides the basic concepts and critical properties of the different nanostructures that are useful for the pathogen detection and photothermal applications. In addition, bio-conjugated nanomaterial based strategies have been discussed with the aim to provide readers an overview of exciting opportunities and challenges in this field.
Article
A study was conducted to demonstrate the use of gold nanoparticles (AuNP) in chemical and biological sensing. AuNPs possessed distinct physical and chemical attributes that made them excellent scaffolds for the fabrication of novel chemical and biological sensors. AuNPs were synthesized in a straightforward manner and made highly stable, while possessing unique optoelectronic properties and providing high surface-to-volume ratio with excellent biocompatibility using appropriate ligands. These synthetic routes and properties of AuNPs made them excellent probes for different sensing strategies. A variety of other ligands had been used to passivate and functionalize AuNPs, while most AuNP functionalization had been done using thiol or thiolated ligands.
Article
Clever combinations of different types of functional nanostructured materials will enable the development of multifunctional nanomedical platforms for multimodal imaging or simultaneous diagnosis and therapy. Mesoporous silica nanoparticles (MSNs) possess unique structural features such as their large surface areas, tunable nanometer-scale pore sizes, and well-defined surface properties. Therefore, they are ideal platforms for constructing multifunctional materials that incorporate a variety of functional nanostructured materials.
Article
Aqueous-dispersed single and binary noble metal nanocrystals have attracted much attention as key materials in many fields, especially in biomedicine, catalysis, etc. Controlled growth of the metal nuclei allow for the manipulation of uniform morphology of final products. This behavior would tailor their unique physiochemical and electronic properties and follows by their practical applications. This review presents an overall picture of kinetic formation of a particle and then summarizes an overview of recent progress in many research groups concerning aqueous- and/or polyol-based syntheses of many types of aqueous-dispersed single metallic and bimetallic nanocrystals with controlled shape. The main advantages in these synthetic approaches for the shape-controlled metal nanocrystals are simple, versatile, environmentally friendly, low cost, pure and single-crystalline products, and high yield. The formed products can be easily dispersed in water medium and compatible for biotechnological field. Particularly the biomolecule (antibody including protein and/or DNA)-conjugated gold nanocrystals have been utilized as an active agent for a broad range of biomedical applications. We expect that this review will have a high potential towards novel materials fabrication and nanotechnological fields.
Article
Melamine that can cause serious damage to the organs of animal or human beings was found to bind to polythymine via hydrogen bonding. With this novel discovery, colorimetric detection of melamine based on label-free and labeled gold nanoparticles was developed, respectively. Both of the methods revealed good selectivity for melamine over other components that may exist in milk and good anti-influence ability. The raw milk samples were pretreated according to the National standard method combined with a solid phase extraction monolithic column. The accurate quantification of melamine as low as 41.7 nM and 46.5 nM was obtained, respectively. It also guarantees fast and reliable readout with naked eyes, making visual detection possible. Further comparison between label-free and labeled based methods was discussed in this paper.
Article
Nanomaterials, such as metal or semiconductor nanoparticles and nanorods, exhibit similar dimensions to those of biomolecules, such as proteins (enzymes, antigens, antibodies) or DNA. The integration of nanoparticles, which exhibit unique electronic, photonic, and catalytic properties, with biomaterials, which display unique recognition, catalytic, and inhibition properties, yields novel hybrid nanobiomaterials of synergetic properties and functions. This review describes recent advances in the synthesis of biomolecule-nanoparticle/nanorod hybrid systems and the application of such assemblies in the generation of 2D and 3D ordered structures in solutions and on surfaces. Particular emphasis is directed to the use of biomolecule-nanoparticle (metallic or semiconductive) assemblies for bioanalytical applications and for the fabrication of bioelectronic devices.
Article
Localized Surface plasmon resonance (LSPR) sensors based on metal nanoparticles, a mode of signal transduction, and biological LSPR sensors, concerned with label-free detection, are studied. To find the functional form of the LSPR peak wavelength's dependence on the dielectric function of the medium, the analytical, frequency-dependent form from the Drude model of the electronic structure of metals is used. LSPR directly detects the target's refractive index and so it is a label-free sensor, in which the measured signal is due only to the presence of the target molecule. LSPR sensing is used to probe biomolecular interactions including nucleic acid hybridization and protein-carbohydrate, cytochrome-inhibitor, aptamer, protein, and toxinreceptor interactions. A scheme for LSPR-based gas sensing is developed by Karakouz et al., in which evaporated gold island films are coated with the polymers polystyrene sulfonic acid (PSS) and polystyrene (PS).
Article
A highly sensitive analytical method based on Au nanoparticles rationally tailored with recognition elements uracil-5-carboxylic acid (UCA) and 2,4,6-trinitrobenzenesulfonic acid (TNBS) for the visual sensing of melamine at the parts-per-billion (ppb) level is described. The tailored Au nanoparticles function as an excellent color indicating reporter and it recognizes the target analytes by triple hydrogen-bonding or charge-transfer interaction in aqueous solution. The interaction of melamine with UCA- or TNBS-tailored reporters induces a rapid visible color change due to the aggregation of reporters. The color change was spectrally monitored to precisely quantify the amount of melamine. The charge-transfer interaction of melamine with TNBS-tailored reporter brings a remarkable change in the spectral signature even at the ppb level. Such an interaction paves the way for the detection of melamine at the 5 ppb level, which is well below the safety limit set by UN food standard commission. This method is highly selective and the common interfering analytes such as cyanuric acid, cytosine, glucose, thymine, uracil, etc., do not interfere in the sensing of melamine. The practical utility of the method is demonstrated by quantifying the amount melamine in real samples.
Article
Gold colloids have fascinated scientists for over a century and are now heavily utilized in chemistry, biology, engineering, and medicine. Today these materials can be synthesized reproducibly, modified with seemingly limitless chemical functional groups, and, in certain cases, characterized with atomic-level precision. This Review highlights recent advances in the synthesis, bioconjugation, and cellular uses of gold nanoconjugates. There are now many examples of highly sensitive and selective assays based upon gold nanoconjugates. In recent years, focus has turned to therapeutic possibilities for such materials. Structures which behave as gene-regulating agents, drug carriers, imaging agents, and photoresponsive therapeutics have been developed and studied in the context of cells and many debilitating diseases. These structures are not simply chosen as alternatives to molecule-based systems, but rather for their new physical and chemical properties, which confer substantive advantages in cellular and medical applications.
Article
With their unique sequence-specific self-assembly and their substrate recognition properties, peptides play critical roles in controlling the biomineralization of inorganic nanostructures in natural systems and in directing the assembly of important soft matter. These attributes render them particularly useful molecules for the fabrication of new materials. Researchers from many scientific disciplines now use peptides to direct the synthesis of new inorganic nanostructures and the assembly of soft biomaterials. In this Review we describe the developments in this field and focus on the versatility of peptides and their ability to direct the composition and structure of new inorganic materials.
Article
Therapeutic peptides/proteins and protein-based antigens are chemically and structurally labile compounds, which are almost exclusively administered by parenteral injections. Recently, non-invasive mucosal routes have attracted interest for administration of these biotherapeutics. Chitosan-based delivery systems enhance the absorption and/or cellular uptake of peptides/proteins across mucosal sites and have immunoadjuvant properties. Chitosan is a mucoadhesive polysaccharide capable of opening the tight junctions between epithelial cells and it has functional groups for chemical modifications, which has resulted in a large variety of chitosan derivatives with tunable properties for the aimed applications. This review provides an overview of chitosan-based polymers for preparation of both therapeutic peptides/protein and antigen formulations. The physicochemical properties of these carrier systems as well as their applications in protein and antigen delivery through parenteral and mucosal (particularly nasal and pulmonary) administrations are summarized and discussed.
Article
Gold nanoparticles have been precipitated in the presence of a stiff polyphenylene dendrimer template with 16 thiomethyl groups on the outside. Powder X-ray diffraction analysis shows an average particle size of similar to3.7 nm; surprisingly, transmission electron microscopy (TEM) reveals a bimodal particle size distribution. Most of the small particles are single crystals and the large ones have multiple crystalline domains, as observed by high resolution TEM. The particles aggregate in the solid state due to the cross-linking ability of the dendrimer. They are reversibly soluble in chloroform and toluene for extended periods of time, and can be solution cast onto flat substrates. A strong plasmon band at 560 nm and a shoulder at similar to370 nm are observed in the UV/Vis spectrum of the material.
Article
The color change induced by triple hydrogen-bonding recognition between melamine and a cyanuric acid derivative grafted on the surface of gold nanoparticles can be used for reliable detection of melamine. Since such a color change can be readily seen by the naked eye, the method enables on-site and real-time detection of melamine in raw milk and infant formula even at a concentration as low as 2.5 ppb without the aid of any advanced instruments.
Article
Nanocrystals are fundamental to modern science and technology. Mastery over the shape of a nanocrystal enables control of its properties and enhancement of its usefulness for a given application. Our aim is to present a comprehensive review of current research activities that center on the shape-controlled synthesis of metal nanocrystals. We begin with a brief introduction to nucleation and growth within the context of metal nanocrystal synthesis, followed by a discussion of the possible shapes that a metal nanocrystal might take under different conditions. We then focus on a variety of experimental parameters that have been explored to manipulate the nucleation and growth of metal nanocrystals in solution-phase syntheses in an effort to generate specific shapes. We then elaborate on these approaches by selecting examples in which there is already reasonable understanding for the observed shape control or at least the protocols have proven to be reproducible and controllable. Finally, we highlight a number of applications that have been enabled and/or enhanced by the shape-controlled synthesis of metal nanocrystals. We conclude this article with personal perspectives on the directions toward which future research in this field might take.
Article
A continuous flow microreactor was used for the synthesis of gold nanoparticles (5 to 50 nm) directly from a gold salt (HAuCl(4)) and a reducing agent (ascorbic acid). Experimental parameters were optimized to obtain narrow size distributions, which were at average two times narrower than those obtained in a conventional synthesis. Additionally, two approaches, i.e., elevation of pH during reaction and hydrophobization of internal reactor surfaces were tested to suppress reactor fouling.
Article
Chitinous material was extracted from mycelia of Aspergillus niger and Mucor rouxii grown in yeast peptone dextrose broth for 15 and 21 days, respectively. The extracted material was characterized for purity, degree of acetylation, and crystallinity and tested for antibacterial and eliciting properties. The maximum glucosamine level determined in the mycelium of A. niger was 11.10% dw and in the mycelium of M. rouxii was 20.13% dw. On the basis of the stepwise extraction of freeze-dried mycelia, it appeared that M. rouxii mycelia contained both chitin and chitosan, whereas A. niger contained only chitin. The yields of crude chitin from A. niger and M. rouxii were 24.01 and 13.25%, respectively, and the yield of chitosan from M. rouxii was 12.49%. Significant amounts (7.42-39.81%) of glucan were associated with chitinous compounds from both species and could not be eliminated by the extraction method used. The degrees of acetylation were determined to be 76.53 and 50.07% for chitin from A. niger and M. rouxii, respectively, and 19.5% for M. rouxii chitosan. The crystallinity of fungal chitin and chitosan was estimated to be less intense than in corresponding materials from shrimp shells. The extracted chitin and chitosan in a concentration of 0.1% reduced Salmonella Typhimurium DT104 2576 counts by 0.5-1.5 logs during a 4 day incubation in tryptic soy broth at 25 degrees C. Furthermore, all tested chitinous materials from fungal sources significantly reduced lesions caused by Botrytis cinerea and Penicillium expansum in harvested apples.
Article
This Account describes a new paradigm for the relationship between the geometry of metallic nanostructures and their optical properties. While the interaction of light with metallic nanoparticles is determined by their collective electronic or plasmon response, a compelling analogy exists between plasmon resonances of metallic nanoparticles and wave functions of simple atoms and molecules. Based on this insight, an entire family of plasmonic nanostructures, artificial molecules, has been developed whose optical properties can be understood within this picture: nanoparticles (nanoshells, nanoeggs, nanomatryushkas, nanorice), multi-nanoparticle assemblies (dimers, trimers, quadrumers), and a nanoparticle-over-metallic film, an electromagnetic analog of the spinless Anderson model.