Shape-Controlled Synthesis of Gold and Silver Nanoparticles

Citrate Synthesis of Gold Nanoparticles - YouTube

Fungal biosynthesis of gold nanoparticles: mechanism …

Stabilized Au and Ag nanoparticles were prepared using heparin derivatized with a diaminopyridine group at the reducing end synthesized through reductive amination (DAPHP). It is believed that the aldehyde on the reducing end of the residual underivatized heparin present in the DAPHP reduces AuCl4 and AgNO3, while the DAP on the derivatized DAPHP provides a strong interaction between its amino/pyridine group and the Au or Ag nanoparticles. The bioconjugates prepared in this synthesis were analyzed by UV-Vis spectroscopy. The UV-Vis spectra recorded on Au and Ag nanoparticles solutions synthesized using DAPHP are shown in . A strong resonance at approximately 533 and 400 nm, respectively, is observed for Au and Ag nanoparticles in solution, due to the excitation of surface plasmon vibrations. The surface plasmon resonance band is shifted towards a higher wavelength, compared with Au and Ag nanoparticles of the similar sizes synthesized with other conventional methods. This shift can be explained by the interaction between the DAPHP and the particles, which influences the surface plasmon resonance band. The UV-Vis spectra of Au and Ag nanoparticle solutions remained unchanged over several months when stored at 20 °C, indicating the nanoparticle size distribution in water was extremely stable. Nanoparticles are stabilized by the bound DAPHP and show no sign of aggregation.

In addition to this, the re-evaluation of the gold salt reduction procedure further improved on achieving nanoparticle size and shape reproducibility.

Pesquise com mais rapidez e eficiência aqui! Gold Nanoparticles

Metal nanoparticles such as gold (Au) and silver (Ag) have recognized importance in chemistry, physics and biology because of their unique optical, electrical and photothermal properties. Such nanoparticles have potential applications in analytical chemistry and have been used as probes in mass spectroscopy, as well as in the colorimetric detection for proteins and DNA molecules. Furthermore, Au nanoparticles have photothermal properties that can be exploited for localized heating resulting in drug release, thus, increasing their potential for therapeutic applications. The ease of synthesizing Au and Ag nanoparticles and their affinity for binding many biological molecules, makes them attractive candidates for study. Various methods have been reported over the last two decades for the synthesis of Au and Ag nanoparticles, which involved the reduction of AuCl4 and AgNO3 with a chemical reducing agent, such as citrate acid, borohydride, or other organic compounds. The functionalization of metal nanoparticles synthesized using such reductants is straightforward resulting in their derivatization with biomolecules including, DNA and proteins. While nanoparticles derivatized with proteins and DNA has been extensively studied, metal nanoparticles derivatized with polysaccharides, such as glycosaminoglycans (GAGs), have thus far been overlooked.

GAGs are negatively charged polysaccharides composed of repeating disaccharides units and can be sulfated at various positions along the polysaccharide chains. These include heparin, heparan sulfate, chondroitin sulfate, hyaluronan, dermatan sulfate, and keratan sulfate. Heparin is the most sulfated GAG and is composed of repeating units of uronic acids, such as glucuronate (GlcA) or iduronate (IdoA), and N-acetylglucosamine (GlcNAc) residues, with an average of 2.7 sulfo groups per disaccharide. Hyaluronan is a non-sulfated GAG with a long repeating chain of GlcA linked to GlcNAc. GAGs, with the exception of hyaluronan, are often found attached to various core proteins, forming larger macromolecules, called proteoglycans. Proteoglycans have diverse biological functions depending on both the core protein and the type and number of GAG chains that are attached. GAGs are ubiquitously found throughout the body of all animals and are recognized by a myriad of proteins. When these proteins interact with GAGs their activity is regulated allowing these proteins to carry out their specific biological functions. For example, heparin and heparan sulfate are involved in anticoagulation, wound healing, angiogenesis, tumor metastasis, and inflammation. Hyaluronan (HA) serves as lubricant and shock absorber in the extracellular matrix of cartilage. The incorporation of carbohydrates onto nanomaterials has recently become an active research area. Jiang and coworkers synthesized poly(glucosamine) (chitosan) - Au hybrid nanospheres using cross-linked low molecular weight chitosan (LMWCS) and ethylenediaminetetraacetic acid (EDTA) composite nanospheres as a precursor reaction system, which involved in-situ reduction of Au ions in polymeric spheres using EDTA as the reducing agent. Gole and coworkers used glucose as a reductant to form nanoparticles using chloroaurate ions entrapped in the thermally evaporated fatty amine film on a glass substrate. Raveendran et al. used β-D-glucose as the reducing agent and starch as a capping agent to prepare starch Ag nanoparticles. Huang et al. used chitosan and heparin as reducing and stabilizing agents for the synthesis of Au and Ag nanoparticles, respectively. Until now, the use of carbohydrates as reducing agents has been largely limited to nanoparticle synthesis. The current study demonstrates the feasibility of synthesizing stable GAGs-nanoparticle bioconjugates to probe biological activities. Synthesis of Au and Ag nanoparticles, using derivatized heparin that is able to bind very strongly with the Au and Ag, and hyaluronan as reducing agents, avoids the need to remove reagents added or any impurities formed during the reaction, affording stable nanoparticles. These nanoparticles were easily purified from unbound or free heparin molecules by centrifugation. In vivo and in vitro studies show that the heparin or hyaluronan metal nanocomposites display important biological activities and biocompatibility to these nanomaterials.

Synthesis of Gold Nanoparticles Using Amino Acids by …

Albumin-templated NIR fluorescent gold nanoclusters were also conjugated with folic acid (FA) and cisplatin prodrug as an integrated theranostic nanoplatform for targeted NIR fluorescence imaging and chemotherapy on 4T1 breast cancer []. FA modification significantly improved the cellular uptake and cytotoxicity of the prepared nanoparticles in the 4T1 breast cancer cells. NIR fluorescence could be used for non-invasive optical bioimaging. In addition, the prepared nanoparticle showed significant inhibition on the growth and lung metastasis of orthotopic 4T1 breast tumors.

Green synthesis of gold nanoparticles using marine …

Albumin-templated Ag nanocluster was discovered with strong singlet oxygen (1O2) generation capacity under light irradiation (≈1.26, Rose Bengal as a standard) and could be applied in photodynamic therapy (PDT) []. The prepared Ag nanocluster exhibited higher 1O2 generation capacity than that of gold nanocluster and commonly available photosensitizers. The prepared Ag nanocluster was also highly biocompatible and fluorescent and could be used to track the cell uptake of the nanoparticle and kill cancer cells through generating 1O2.

Synthesis Of Gold Nanoparticles Biology Essay

There have been many excellent reviews on albumin-based nanomedicine from different aspects, including preparation technologies, hybrid albumin nanomedicine, half-life extension, bioconjugate chemistry, theranostic applications [, , , -]. These reviews have given clear summaries on albumin-based nanomedicine and prompted the quick development of the technologies in this field, however, none of them focused on the roles of albumin in constructing multifunctional nanoparticles. The unique multi-properties of albumin give different opportunities to construct multifunctional nanoparticles with expected properties. In this review, we summarize the different strategies with albumin as different roles for constructing albumin-based nanosystems aimed at different applications and thereby aid researchers in their study of this field through reasonably designed nanomaterials (Figure ).