Small-sized Gold Nanoparticles Research Articles

A Uni-Micelle Approach for the Controlled Synthesis of Monodisperse Gold Nanocrystals.

Small-size gold nanoparticles (AuNPs) are showing large potential in various fields, such as photothermal conversion, sensing, and medicine. However, current synthesis methods generally yield lower, resulting in a high cost. Here, we report a novel uni-micelle method for the controlled synthesis of monodisperse gold nanocrystals, in which there is only one kind micelle containing aqueous solution of reductant while the dual soluble Au (III) precursor is dissolved in oil phase. Our synthesis includes the reversible phase transfer of Au (III) and "uni-micelle" synthesis, employing a Au (III)-OA complex as an oil-soluble precursor. Size-controlled monodisperse AuNPs with a size of 4-11 nm are synthesized by tuning the size of the micelles, in which oleylamine (OA) is adsorbed on the shell of micelles and enhances the rigidity of the micelles, depressing micellar coalescence. Monodisperse AuNPs can be obtained through a one-time separation process with a higher yield of 61%. This method also offers a promising way for the controlled synthesis of small-size alloy nanoparticles and semiconductor heterojunction quantum dots.

Tracking epithelial-mesenchymal transition in breast cancer cells based on a multiplex electrochemical immunosensor

Epithelial-mesenchymal transition (EMT) promotes tumor cell infiltration and metastasis. Tracking the progression of EMT could potentially indicate early cancer metastasis. A key characteristic of EMT is the dynamic alteration in the molecular levels of E-cadherin and N-cadherin. Traditional assays have limited sensitivity and multiplexing capabilities, relying heavily on cell lysis. Here, we developed a multiplex electrochemical biosensor to concurrently track the upregulation of N-cadherin expression and reduction of E-cadherin in breast cancer cells undergoing EMT. Small-sized gold nanoparticles (Au NPs) tagged with redox probes (thionin or amino ferrocene) and bound to two types of antibodies were used as distinguishable signal tags. These tags specifically recognized E-cadherin and N-cadherin proteins on the tumor cell surface without cross-reactivity. The diphenylalanine dipeptide (FF)/chitosan (CS)/Au NPs (FF-CS@Au) composites with high surface area and good biocompatibility were used as the sensing platforms for efficiently fixing cells and recording the dynamic changes in electrochemical signals of surface proteins. The electrochemical immunosensor allowed for simultaneous monitoring of E- and N-cadherins on breast cancer cell surfaces in a single run, enabling tracking of the EMT dynamic process for up to 60 h. Furthermore, the electrochemical detection results are consistent with Western blot analysis, confirming the reliability of the methodology. This present work provides an effective, rapid, and low-cost approach for tracking the EMT process, as well as valuable insights into early tumor metastasis.

Experimental Evaluation of Kinetic Characteristics of SiO2@AuNPs Nanocomposite and BSA-stabilized gold Nanoparticles toward Peroxidase-Mediated Reactions

In this study, BSA-stabilized gold nanoparticles and SiO2 @AuNPs nanocomposite were synthesized and then characterized by the TEM imaging method. The average size of BSA-stabilized gold nanoparticles was found to be as small as 13 nm while the SiO2 @AuNPs nanocomposite showed a mean size of 204 nm. The experimental studies revealed that both BSA-stabilized gold nanoparticles and SiO2 @AuNPs nanocomposite exhibit intrinsic peroxidase-like activity. Hence, to explore more precise no their catalytic efficiency and substrate affinity of them, the kinetic characteristics of both nanozymes were quantified using the Menten kinetic model, and the provided results were compared. Upon using TMB as peroxidase substrate, Vmax of 0.022 µM min-1 and a Km of 0.06 mM for the SiO2 @AuNPs nanocomposite was achieved while for the BSA-stabilized gold nanoparticles, a Vmax and Km at about 0.263 μM min-1and 0.03 mM, in order, was estimated. The Vmax of BSA-stabilized gold nanoparticles was 12.0-fold higher than that of SiO2 @AuNPs nanocomposite, revealing that the catalytic efficiency of BSA-stabilized gold nanoparticles is 12.0-fold higher than SiO2 @AuNPs nanocomposite. Besides, the Km value of SiO2 @AuNPs nanocomposite was 2-order higher than that of BSA-stabilized gold nanoparticles, indicating that the substrate affinity toward BSA-stabilized gold nanoparticles is 2.0-order higher than the SiO2 @AuNPs nanocomposite. Since, the active nodes of both nanozymes are same (i.e., gold), the difference between their catalytic efficiency and affinity can be assigned to their different sizes and the ability of the active nodes to bind the substrate. Based on the results of this work, small-size BSA-stabilized gold nanoparticles are characteristically more efficient peroxidase mimic materials than the SiO2 @AuNPs nanocomposite.

Bio-inspired spindle-shaped wrinkled Au/ZnO nanoparticles for H2S-sensing enhancement

The construction of fast response, low detection limit and high stability gas sensors by means of bionics is of great significance, for the sake of fabricating more efficient and compatible materials and exploring their functional principles. The high olfactory sensitivity of dogs and mice in nature is closely related to the wrinkled structure of their turbinates, which provides inspiration for us to design the structure of gas-sensing sensing materials. In our study, various scales and concentrations Au nanoparticles were deposited on spindle-shaped wrinkled ZnO nanoparticles via a facile hydrothermal method and subsequent a series of reduction process, resulting in different sensing performances toward H2S: when the loading amount of small-sized gold nanoparticles was 0.5 wt% (0.5 wt% Au/ZnO), sample showed the highest response value of 39.23 at the optimal working temperature of 215 °C, which was 6.4 times that of pure wrinkled ZnO. The superior sensing performance can be attributed to the control of two mechanisms: adsorption-desorption mechanism and sulfurization-desulfurization mechanism. Moreover, 0.5 wt% Au/ZnO constructed in a sample and low-cost way provides a strategy to design bio-inspired materials for evaluate trace concentrations of H2S.

Ultrasensitive colorimetric detection of tetracyclines based on in-situ growth of gold nanoflowers.

A colorimetric method based on in-situ generation of gold nanoflowers for the detection of tetracyclines (TCs) was proposed. We found that gold nanoflowers could be formed in the HAuCl4-NH2OH redox reaction directly without the addition of small-sized gold nanoparticles (Au NPs) as seeds when an alkaline borax buffer solution was employed as the reaction medium. Interestingly, the shape and size of the generated gold nanoflowers were regulated with TC. Briefly, large flower-like gold nanoparticles were formed with a low concentration of TC while small spherical gold nanoparticles were generated with a high concentration of TC. The generated gold nanoflowers exhibited different surface plasmon absorption (SPR) properties. Thus, a simple and rapid colorimetric method was established for the detection of TC antibiotics. This method exhibited high sensitivity for the detection of TC, oxytetracycline (OTC), and doxycycline (DC) with detection limits of 2.23nM, 1.19nM, and 5.81nM, respectively. The proposed colorimetric method was applied to the determination of TC in both milk samples and water samples.

On the Importance of Fresh Stock Solutions for Surfactant-Free Colloidal Syntheses of Gold Nanoparticles in Alkaline Alcohol and Water Mixtures

A room temperature surfactant-free synthesis of gold nanoparticles in the size range 10–20 nm that only requires HAuCl4 as the precursor, NaOH as the base, water as the solvent and a mono-alcohol such as methanol or ethanol as the reducing agent, has recently been detailed. This approach is promisingly simple to obtain colloids stable for months. Here, it is shown that the use of fresh stock solutions of base is one key to ensure the formation of stable surfactant-free small-sized gold nanoparticles. The need for relatively freshly prepared stock solutions of base does not appear to be as crucial for syntheses using stabilizers and/or viscous solvents such as glycerol. The possibly overlooked importance of the age of the stock solution of base might account for the limited interest to date for the simple room temperature synthesis in low viscosity mono-alcohols highlighted.

Synthesis of amino talc-like clay-supported Au nanoparticles with outstanding catalytic activity for 4-nitrophenol reduction

Studies on synthesizing gold nanoparticle-based catalysts to reduce the amount of gold and improve the catalytic activity at the same time are still crucial. The reduction reaction of 4-nitrophenol (a toxic compound) to 4-aminophenol (a non-toxic compound and essential material for the pharmaceutical industries) is a standard reaction for analyzing the catalytic activity of AuNPs. A capping agent is indispensable for producing stable and size-controlled gold nanoparticles (AuNPs) and in maintaining the catalytic activity of the AuNPs. However, some previous studies reported that capping agents reduced the catalytic activity of AuNPs through a surface-blocking phenomenon. Moreover, introducing a framework for capped AuNPs could be another consideration to increase the dispersion of AuNPs in an aqueous medium, eventually improving the catalytic activity of the AuNPs. Amino talc-like clay, a relatively non-toxic and well-dispersed layered material in aqueous solution, has been used as a framework for AuNPs. The present study reports the AuNP synthesis using delaminated amino talc-like clay (DAC) as a framework that brings about gold nanoparticles with superior catalytic activity to other supports. Moreover, the effect of the reducing agent concentration, Mn addition and pH conditions are discussed in determining this excellent property. DAC shows a promising role as a AuNP framework which increases the catalytic activity by improving the dispersion and stability of the material in the colloidal system. The pH-dependent stacking structure arrangement of the DAC support was a determining factor of Kapp for the 4-nitrophenol reduction reaction by DAC stabilized AuNPs. Under acidic conditions, the stacking structure of DAC was destroyed, providing more open space for the AuNPs attached to the clay surface, which increased the Kapp value. On the contrary, under basic conditions, the stacking structure of DAC was re-arranged, closing the surface space of the AuNPs attached to the interlayer clay, which decreased the Kapp value. Moreover, the DAC stabilizer provided a partially capped AuNP structure in neutral and acidic aqueous solutions, which prevented the catalytically active surface blocking phenomenon occurring in the ordinary capping type. Mn addition during the synthesis process controlled the production of small-size gold nanoparticles and increased the catalytic activity of the material.

Nephrotoxicity induced by different diameters of sphere gold nanoparticles with special emphasis on the nephroprotective role of quercetin.

Although, gold nanoparticles (GNPs) are attracting more and more attention due to their ease of synthesis, modification, and great potential value in biomedical applications, exhibited harmful effects on human health and other living species. Quercetin (Qur) clarifies diverse pharmacological effects, especially anti-inflammatory, antiapoptotic, and antioxidant ones. This study aimed to evaluate the probable nephrotoxicity induced by different diameters of sphere GNPs, as well as the nephroprotective role of Qur. A total of 54 healthy mature male albino rats were grouped and treated with or without sphere GNPs; 10, 20, and 50 nm and Qur (200 mg/kg b.wt.). The effects of GNPs and Qur were estimated through the collection of blood and kidney samples from euthanized rats and performed biochemical, histopathological, and immunohistochemical investigations. In comparison between different diameters of GNPs, the 10 nm GNPs revealed more significant elevations in all renal function parameters: creatinine, urea, blood urea nitrogen, and uric acid followed by 20 nm then 50 nm. Pre-cotreatment with Qur decreased all renal functional values. Histopathologically, 10 nm revealed the most potent renal pathological changes represented in the renal cortex with cloudy swelling of renal tubules, hypercellularity of some glomeruli, severe congestion of renal blood vessels, focal inter tubular edema, and vascular endotheliosis (degeneration of endothelium). In addition, the renal medulla revealed perivascular inflammatory cellular infiltration, perivascular fibrosis, intra tubular glycogen deposition, and casts deposition of mainly cellular casts. On the other hand, the Qur treatment ameliorated most of these pathological changes. The size of GNPs is pivotal in their pathological effect on renal tissues where the small-sized GNPs; 10 nm have more potent cytotoxic, inflammatory, and apoptotic effects rather than the larger ones. Otherwise, Qur clarified a significant mitigating role against the nephrotoxicity of the GNPs.

Insights into the remarkable attenuation of hen egg white lysozyme amyloid fibril formation mediated by biogenic gold nanoparticles stabilized by quercetin-functionalized tara gum

Aberrant protein misfolding and/or aggregation and fibrillation has been linked to the pathogenesis of several debilitating chronic diseases including Alzheimer's and Parkinson's disease. Inhibiting protein amyloidogenesis has been proposed as a viable strategy to prevent or ameliorate associated disorders. Herein, we investigated the anti-amyloidogenic properties of biogenic gold nanoparticles (QTG-GNP) prepared via a simple green chemistry route and stabilized by quercetin-functionalized tara gum (QTG). The synthesized QTG-GNP was extensively characterized for its physicochemical attributes via UV–visible spectroscopy, TEM, FESEM, EDX, DLS/Zeta potential, FTIR, RAMAN, XRD, XPS, and TGA analyses, as well as for its biological properties. The results revealed that small-sized (5.01 ± 1.17 nm), well-dispersed, highly stable and round-shaped biogenic gold nanoparticles were successfully synthesized at room temperature with QTG as the sole reductant /stabilizer. Importantly, QTG-GNP demonstrated potent anti-aggregation and fibrillation inhibitory effects against amyloidogenic hen egg white lysozyme (HEWL). Also, QTG-GNP was able to dissociate pre-formed HEWL amyloid fibrils. Furthermore, the constructed nanoparticles exhibited potent anti-radical activities against DPPH and ABTS+ and were cytocompatible with mouse L929 fibroblast cells. On the basis of these findings, it was established that QTG-GNP holds strong prospects for further development as an agent for countering protein aggregation and associated disease conditions.

Synthesis of Urchin-Shaped Gold Nanoparticles Utilizing Green Reducing and Capping Agents at Different Preparation Conditions: An In Vitro Study

Employing environmentally friendly reducing and capping materials to synthesize gold nanoparticles is an exciting research point. However, the used materials usually need a long reduction time that can take days. In this work, the instantaneous production of small-sized (less than 20 nm) gold nanoparticles is investigated using ascorbic acid, gelatin, and a mixture of the two agents at different preparation conditions (at room temperature; 20 ± 3 °C and near boiling temperature; 95 ± 3 °C). Particle size analysis, as well as transmission electron microscopy, were used to assess the produced particles’ physical characteristics. The structural changes and optical characteristics of the nanoparticles were monitored using UV–visible spectroscopy. Fourier Transform Infrared spectroscopy (FTIR) was used to establish the presence of a gelatin coating over the gold nanoparticles. The morphology of the produced nanoparticles at 95 ± 3 °C was spherical with a size ranging from 8–18 nm, whereas urchin-shaped nanoparticles ranging from 24–100 nm were formed at 20 ± 3 °C reaction temperature. The presence of hydroxyl and amine groups associated with the gelatin was confirmed using FTIR. This could be a step for wider usage of green synthesized nanogold particles in several applications.

Role of tannic acid in desiging of electrically active and magnetic gold nanoparticles and enhanced photovoltaic performance of gold@titania photoanode in DSSC

We describe here in significance of tannic acid in obtaining size dependent electrochemically active and magnetic gold nanoparticles (GNPs). In this account, two types of GNPs (SCGNPs and SC-TAGNPs) were synthesized by using sodium citrate and sodium citrate-tannic acid as reducing agents, respectively. Highly monodispersed, uniformly distributed and small size GNPs were produced when tannic acid was used together with sodium citrate. SC-TAGNPs exhibited room temperature ferromagnetism while SCGNPs revealed diamagnetism. With higher anodic peak current and lower charge transfer resistance, the SC-TAGNPs exhibited better conductivity and electron transfer ability than SCGNPs. Mott-Schottky analysis revealed n-type semiconducting behavior of GC/SCGNPs & GC/SC-TAGNPs and showed positive shift in flat-band potential of GC/SC-TAGNPs compared to GC/SCGNPs suggesting better conductivity of SC-TAGNPs. Subsequently, SCGNPs and SC-TAGNPs were added to TiO2 nanoparticles to fabricate modified titania photoanodes (SCGNPs@TiO2 and SC-TAGNPs@TiO2) for dye-sensitized solar cells (DSSCs) application. With the use of TiO2, SCGNPs@TiO2 and SC-TAGNPs@TiO2 photoanodes, the short-circuit current density (JSC) was observed to be 2.18, 4.50 and 6.68 mA/cm2, while energy conversion efficiency (η) was found to be 0.75, 1.74 and 2.50%, respectively. The TiO2 photoanode employing SC-TAGNPs exhibited remarkably increased JSC and η by ∼48 and ∼44%, respectively, then SCGNPs modified photoanode.

Photothermal therapy of cancer cells enhanced by glutathione (GSH) modified small-sized gold nanoparticles

ABSTRACT Small-sized gold nanoparticles (∼3nm) coated with Glutathione (GSH) ligand have designed as an active agent in photothermal therapy (PTT). GSH is pH-sensitive surface that have a fast response property to the variation in pH conditions, especially between normal (∼7.4) and cancer cell (6–6.5), that help the evaluation of the target and toxic effect of the cancer rather than normal cells. Results revealed considerable toxic effects of GSH-AuNPs accumulation in cancer cells for both green and NIR laser irradiation. The GSH-AuNPs represent promising agents for developing the safety issues of photothermal cancer treatment by; the selective targeting of the cancer rather than normal cells, reducing the NPs toxicity by their size overlapping with the renal clearance barrier of kidney filtration (~5.5 nm), and promoting the photothermal performance in the NIR region, in which light penetration into deep cancer regions are more interested.

Small size gold nanoparticles enhance apoptosis-induced by cold atmospheric plasma via depletion of intracellular GSH and modification of oxidative stress

Gold nanoparticles (Au-NPs) have attracted attention as a promising sensitizer owing to their high atomic number (Z), and because they are considered fully multifunctional, they are preferred over other metal nanoparticles. Cold atmospheric plasma (CAP) has also recently gained attention, especially for cancer treatment, by inducing apoptosis through the formation of reactive oxygen species (ROS). In this study, the activity of different sized Au-NPs with helium-based CAP (He-CAP) was analyzed, and the underlying mechanism was investigated. Treating cells with only small Au-NPs (2 nm) significantly enhanced He-CAP-induced apoptosis. In comparison, 40 nm and 100 nm Au-NPs failed to enhance cell death. Mechanistically, the synergistic enhancement was due to 2 nm Au-NPs-induced decrease in intracellular glutathione, which led to the generation of intracellular ROS. He-CAP markedly induced ROS generation in an aqueous medium; however, treatment with He-CAP alone did not induce intracellular ROS formation. In contrast, the combined treatment significantly enhanced the intracellular formation of superoxide (O2• −) and hydroxyl radical (•OH). These findings indicate the potential therapeutic use of Au-NPs in combination with CAP and further clarify the role of Au-NPs in He-CAP-aided therapies.

Green synthesis of gold nanoparticles using Sargassum carpophyllum extract and its application in visual detection of melamine

Small-sized gold nanoparticles (AuNPs) were prepared in the extract of Sargassum carpophyllum which had protective and reductive effects. The method is green, clean, and simple. The Gold nanoparticles prepared by using Sargassum carpophyllum extract (SAuNPs) have good biocompatibility and are suitable for biosensors, tumor hyperthermia and food safety testing. The aim of this work is to explore a green way to prepare the wine red nanoparticles without any adapters and to detect melamine (Mel) visually in real milk samples. The precursor of AuNPs used was HAuCl4. In the visual detection of melamine, the results showed that the color of SAuNPs changed from wine red to purple and then to blue black with the increase of melamine concentration. Meanwhile, UV–vis analysis showed that when the concentration of melamine was in the range of 1.8–2.6 μM, the absorbance ratio (A650/A520) was positively correlated with the concentration of melamine (R2 = 0.998), and the detection limit was 1.82 μM. This method has been successfully applied to the determination of Mel in milk samples with satisfactory results.

Laser enhancement of cancer cell destruction by photothermal therapy conjugated glutathione (GSH)-coated small-sized gold nanoparticles.

The current study presents the employment of glutathione (GSH)-modified small-sized gold nanoparticles (AuNPs) ~ 3nm in photothermal therapy (PTT), to evaluate the targeting and the toxic effect of cancer rather than normal cells. GSH is pH-sensitive surfaces that exhibit a fast response to the variation in pH conditions between normal (~ 7.4) and cancer cells (6-6.5). Results showed a considerable toxic impact via GSH-AuNP accumulation in cancer cells by both green and NIR laser irradiation. A proportional relation of cellular death to AuNP concentration, exposure time, and light-to-heat conversion efficiency has been demonstrated. The small-sized GSH-AuNPs represent promising agents for developing the safety issues of photothermal cancer treatment by the selective targeting of cancer rather than normal cells, reducing the NP toxicity by their size overlapping with the renal clearance barrier of kidney filtration (~ 5.5nm), and promoting the photothermal performance in the NIR region, in which light penetration into deep cancer regions is more interested.

Highly fluorescent silicon quantum dots decorated silica microspheres for selective detection and removal of Au3+ and subsequent catalytic application

Sensitive detection and efficient removal of Au3+ are important for environmental monitoring and remediation. In this study, silicon quantum dots (SiQDs) were prepared with 3-aminopropyl trimethoxysilane as the silicon source and boric acid as the doping substance to enhance fluorescence quantum yield. The obtained SiQDs possessed fluorescence sensing ability of Au3+ and were successfully decorated on the mesoporous silica microspheres (SiO2), giving SiO2-SiQDs. Owing to the high affinity for Au3+ and the relatively large surface area, the SiO2-SiQDs exhibited not only selective fluorescence detection of Au3+ in water matrix with a relatively low limit of detection (13.67μgL−1), but also efficient adsorption of Au3+ with a maximal adsorption capacity of 530.7mgg−1. Besides, the Au3+ adsorbed on the SiO2-SiQDs could be in-situ reduced into evenly dispersed small-size gold nanoparticles, showing high catalytic efficiency for the reduction of 4-nitrophenol. The remarkable performance of SiO2-SiQDs on detection, adsorption and reusability demonstrated its multi-purposed applicabilities.

Multiple plasmon resonances in small-sized citrate reduced gold nanoparticles

Metallic nanoparticles exhibit localized surface plasmon resonances resulting from the coherent oscillation of free electrons in response to electric field from incident electromagnetic radiation. In this work, the dependence of peak surface plasmon resonance of gold nanoparticles on the particle size using UV–Vis spectra is shown. Small-sized gold nanoparticles (10–15 nm) were prepared through citrate reduction method. From theoretical modelling based on their resonance peaks and full wave at half maximum, the gold nanoparticles were found to have a narrow size distribution of ∼12 nm optimized over 1.0–1.10 mL of the citrate. A comparison of the experimental data and data from multiple scattering theory revealed that the plasmon resonances were centered at wavelengths between 520 and 518 nm for all samples under citrate volume range from 0.85 to 1.15 mL. Further analysis indicated that, small sized AuNPs exhibited multiple resonances, which could be attributed to the radiative interband recombination between the sp- and d-bands.

Magnetic-porous microspheres with synergistic catalytic activity of small-sized gold nanoparticles and titania matrix

Fe3O4 nanoparticles immobilized on porous titania in micron-size range were decorated with small-sized gold nanoparticles and used as a plasmonic catalyst for the reduction of 4-nitrophenol. Monodisperse-porous magnetic titania microspheres were synthesized with bimodal pore-size distribution by the sol-gel templating method. Small-sized gold nanoparticles obtained by the Martin method were attached onto the aminated form of the magnetic titania microspheres. A significant enhancement in the catalytic activity was observed using the gold nanoparticle-decorated magnetic titania microspheres compared to gold nanoparticle-decorated magnetic silica microspheres because of the synergistic effect between small-sized gold nanoparticles and titania. The synergistic effect for gold nanoparticle-attached magnetic titania microspheres could be explained by surface plasmon resonance-induced transfer of hot electrons from gold nanoparticles to the conduction band of titania. Using the proposed catalyst, 4-nitrophenol could be converted to 4-aminophenol in an aqueous solution within 0.5 min. The 4-nitrophenol reduction rates were 2.5–79.3 times higher than those obtained with similar plasmonic catalysts. The selection of micron-size, magnetic, and porous titania microspheres as a support material for the immobilization of small-sized gold nanoparticles provided a recoverable plasmonic catalyst with high reduction ability.

Highly sensitive determination of dopamine based on the aggregation of small-sized gold nanoparticles

In this study, a highly selective and sensitive colorimetric method is developed for the determination of dopamine (DA) based on the aggregation of small gold nanoparticles (AuNPs). It is relied upon the size-dependent aggregation behavior of AuNPs induced by DA in the absence and presence of copper ions, offering a simple and sensitive method for detection of DA. The hydroxyl groups in the adjacent dopamine molecules induce efficiently the aggregation of 5 nm AuNPs by intermolecular hydrogen bonding, which leads to a change in color, from orange red to purple. The proposed colorimetric method gives an excellent linear range of 0.02–0.7 μM, with detection limit of 3.3 nM (3σ). This sensing strategy shows excellent characteristics for detection of DA in biological fluids.

Biocompatible, small-sized and well-dispersed gold nanoparticles regulated by silk fibroin fiber from Bombyx mori cocoons

Biocompatible, small-sized but well-dispersed gold nanoparticles (Au NPs) remain a major challenge for their synthesis. Here a convenient solution impregnation technique is developed to prepare such Au NPs under the regulation of degummed silk fibroin fibers (SFFs) extracted from Bombyx mori cocoons. SFFs play multiple roles in the formation of Au NPs such as reactive substrate to capture AuCl4- ions by the chelation of -C = O, reducing agent for Au(0) by the reduction of -OH, and modifiers to render biocompatible Au NPs by some functional groups and biomolecules. The as-prepared Au NPs with a size of 7–10 nm are embedded in the solid SFF substrate, and can disperse well in the liquid system by the disintegration of SFFs into silk fibroin (SF) in a certain CaCl2 solution. The biocompatible Au NPs exhibit uniform small size and distribute stably in both solid and solution states, which have distinctive properties and functional advantages, and bring great convenience to their storage and transportation.