Gold Nanocomposites Research Articles

Surface Functionalized Plasmonic Sensors for Uric Acid Detection With Gold-Graphene Stacked Nanocomposites

Abstract This study presented a surface-functionalized sensor probe using 3-aminopropyltriethoxysilane (APTES) self-assembled monolayers on a Kretschmann-configured plasmonic platform. The probe featured stacked nanocomposites of gold (via sputtering) and graphene quantum dots (GQD, via spin-coating) for highly sensitive and accurate uric acid (UA) detection within the physiological ranges. Characterization encompassed the field emission scanning electron microscopy for detailed imaging, energy-dispersive X-ray spectroscopy for elemental analysis, and Fourier transform infrared spectroscopy for molecular identification. Surface functionalization increased sensor sensitivity by 60.64%, achieving 0.0221 °/(mg/dL) for the gold-GQD probe and 0.035 5 °/(mg/dL) for the gold-APTES-GQD probe, with linear correlation coefficients of 0.8249 and 0.8509, respectively. The highest sensitivity was 0.070 6 °/(mg/dL), with a linear correlation coefficient of 0.993 and a low limit of detection of 0.2 mg/dL. Furthermore, binding affinity increased dramatically, with the Langmuir constants of 14.29 µM−1 for the gold-GQD probe and 0.000 1 µM−1 for the gold-APTES-GQD probe, representing a 142 900-fold increase. The probe demonstrated notable reproducibility and repeatability with relative standard deviations of 0.166% and 0.013%, respectively, and exceptional temporal stability of 99.66%. These findings represented a transformative leap in plasmonic UA sensors, characterized by enhanced precision, reliability, sensitivity, and increased surface binding capacity, synergistically fostering unprecedented practicality.

Effect of vildagliptin conjugated monometallic nanoparticles and bimetallic nanocomposites on diabetes-induced cognitive deficit

Oxidative stress is one of the major causes of different metabolic disorders, including diabetes, cardiovascular diseases, neurodegenerative diseases and cancers. Some metabolic disorders like diabetes mellitus leads to secondary complications after micro and macrovascular complications. Some of the most prevalent neurodegenerative diseases, like cognitive impairment and Alzheimer's disease, are found in chronic diabetic patients. The present study is designed to understand the mechanism of interconnection between diabetes mellitus and cognitive deficit using the alloxan model of diabetes-induced cognitive deficit in the rat model. The alloxan monohydrate produces reactive oxygen species, producing superoxide free radicals, hydrogen peroxide and hydroxyl radicals. The hydroxyl radicals ultimately cause the death of beta cells, causing diabetes. Hence, the correlation of oxidative stress and neurodegeneration in cognitive impairment is the trigger for this study. In the present study, we investigate the ameliorative effect of vildagliptin (VLD) and its conjugated nanoparticles against alloxan-associated brain damage due to oxidative stress. The gold (Au), selenium (Se) nanoparticles, and bimetallic (Se@Au) nanocomposites of VLD are synthesized and assessed for improvement in their brain availability. The in-vitro antioxidant evaluation of the VLD and nanoparticles is done using DPPH, ABTS, and FRAP assay. The memory-related neurobehavioral studies, in-vivo antioxidant studies, in-vivo biochemical studies, and histopathological examinations are evaluated in rat brains. The VLD and its nanoformulations exhibited in-vitro and in-vivo antioxidant properties significantly (p < 0.01). They reduced the activity of AChE and nitrite in the alloxan diabetic rats. The bimetallic Se@Au VLDNCs displayed a more protective effect than VLD, VLD–AuNPs, and VLD–SeNPs.

Resin bound gold nanocomposites assisted SE/ATR-FTIR spectroscopy for detection of pymetrozine insecticide in vegetable samples

The goal of this work was to assess the competence of organic hydrophobic resin bound gold nanocomposites (OH/R-AuNCs) for detection of pymetrozine insecticide from vegetable samples employing surface-enhanced/attenuated total reflectance-Fourier transform infrared (SE/ATR-FTIR) spectroscopy. The adsorption isotherm models, including the Langmuir, Freundlich and Temkin, are tested to reveal the interactive behaviour between the OH/R-AuNCs and pesticide. The adsorption occurs principally by London–Van der Waals dispersion interactions and hydrogen bonding interactions between the surface of OH/R-AuNCs materials and the hydrophobic part of pesticide molecule. The characteristic absorption band obtained at 3019.94 cm−1 was utilized for the quantitative analysis of pymetrozine insecticide in vegetable samples. The method was found to be accurate and precise, with mean recovery values in the range of 94.5–110 %, correlation coefficient of 0.992 %, and detection limit of 2.65 μg mL−1. The adsorption efficiency of the designed OH/R-AuNCs significantly influences the SE/ATR-FTIR response of the pymetrozine around 90 %. The optimized and validated method was applied to determine the residual concentrations of the pymetrozine that had been applied to vegetable samples.

Synthesis of Chi-sphere silver nanocomposite and nanocomposites of silver, gold, and S@G using a chitosan biopolymer extracted from potato peels and their antimicrobial application

Chitin and chitosan have been proven to have numerous applications in biomedical, pharmaceutical, and industrial fields. In the present study, chitin structural polymer was extracted from potato peel wastes by the use of chemical methods and chitosan biopolymer was generated through the deacetylation of the isolated potato peel chitin. On a dry weight basis, the yield of chitin content of the potato peel wastes is 49.80±1.2 % and the yield of deacetylated potato peel chitin (potato peel chitosan) is 47.60±1.8 %. It was characterized by FTIR and 1H NMR studies. Consequently, the potato peel chitosan was employed in the synthesis of Chitosan-Silver-Nanocomposite-Sphere (Chi-SNC-Sphere), and other metal nanocomposite of silver (C.g-CSNCs), gold (C.g-CGNCs), and bimetallic (C.g-CS@GNCs). The physicochemical features of the resulting products were characterized using UV-Vis, FT-IR, PXRD, FESEM, TEM, and EDAX. The FESEM unveiled a smooth, spherical, and nonporous surface morphology of the synthesized Chi-SNCs-Sphere, while the remaining three have surfaces that appeared in the form of flakes. As per TEM images, particles were visible in black-spherical (C.g-CSNC) and black-multi-shapes (C.g-CSNC, C.g-CS@GNC) nanostructures. Their sizes were confined within the range of 1–10 nm, with average values of 4.36 nm±0.40–5.85 nm±0.42. On the basis of BET analysis, C.g.CSNCs C.g-CS@GNC and C.g.CGNCs under identical conditions possess the surface area of 69.92 m2g−1, 52.35 m2g−1, and 49.75 m2g−1 respectively. The nanomaterials were found stable as revealed by the study of zeta potential which is found in the range of +41.3–56.2. The results of the bioassay for antibacterial activity against P. aeruginosa and S. aureus uncovered that the Chi-SNCs-Sphere, C.g-CSNCs, and C.g-CS@GNCs demonstrated superior activities than C.g-CGNCs. According to statistical analysis results of one-way ANOVA of antibacterial results against S. aureus, the P-value F- calculated F-critical was 0.99,1.5 and 3.4 and for P. aeruginosa; P-value, F-calculated, F-critical was 0.80, 0.22 and 5.94 respectively. Minimum inhibitory concentration (MIC) was found most significant for C.g-CSNC (20 µg/mL) due to its higher surface area. These activities could be attributed to the synergistic effect of the metal nanoparticles, potato peel chitosan, and the plant extract that was used for the reduction, stabilization, and biofunctionalization.

Gold-Hydrogel Nanocomposites for High-Resolution Laser-Based 3D Printing of Scaffolds with SERS-Sensing Properties.

Although visible light-based stereolithography (SLA) represents an affordable technology for the rapid prototyping of 3D scaffolds for in vitro support of cells, its potential could be limited by the lack of functional photocurable biomaterials that can be SLA-structured at micrometric resolution. Even if innovative photocomposites showing biomimetic, bioactive, or biosensing properties have been engineered by loading inorganic particles into photopolymer matrices, main examples rely on UV-assisted extrusion-based low-resolution processes. Here, SLA-printable composites were obtained by mixing a polyethylene glycol diacrylate (PEGDA) hydrogel with multibranched gold nanoparticles (NPs). NPs were engineered to copolymerize with the PEGDA matrix by implementing a functionalization protocol involving covalent grafting of allylamine molecules that have C═C pendant moieties. The formulations of gold nanocomposites were tailored to achieve high-resolution fast prototyping of composite scaffolds via visible light-based SLA. Furthermore, it was demonstrated that, after mixing with a polymer and after laser structuring, gold NPs still retained their unique plasmonic properties and could be exploited for optical detection of analytes through surface-enhanced Raman spectroscopy (SERS). As a proof of concept, SERS-sensing performances of 3D printed plasmonic scaffolds were successfully demonstrated with a Raman probe molecule (e.g., 4-mercaptobenzoic acid) from the perspective of future extensions to real-time sensing of cell-specific markers released within cultures. Finally, biocompatibility tests preliminarily demonstrated that embedded NPs also played a key role by inducing physiological cell-cytoskeleton rearrangements, further confirming the potentialities of such hybrid nanocomposites as groundbreaking materials in laser-based bioprinting.

Tyrosol-gold nanoparticle functionalized acacia gum-PVA nanofibers for mitigation of Candida biofilm

Increasing incidences of fungal infections and prevailing antifungal resistance in healthcare settings has given rise to an antifungal crisis on a global scale. The members of the genus Candida, owing to their ability to acquire sessile growth, are primarily associated with superficial to invasive fungal infections, including the implant-associated infections. The present study introduces a novel approach to combat the sessile/biofilm growth of Candida by fabricating nanofibers using a nanoencapsulation approach. This technique involves the synthesis of tyrosol (TYS) functionalized chitosan gold nanocomposite, which is then encapsulated into PVA/AG polymeric matrix using electrospinning. The FESEM, FTIR analysis of prepared TYS-AuNP@PVA/AG NF suggested the successful encapsulation of TYS into the nanofibers. Further, the sustained and long-term stability of TYS in the medium was confirmed by drug release and storage stability studies. The prepared nanomats can absorb the fluid, as evidenced by the swelling index of the nanofibers. The growth and biofilm inhibition, as well as the disintegration studies against Candida, showed 60–70 % biofilm disintegration when 10 mg of TYS-AuNP@PVA/AG NF was used, hence confirming its biological effectiveness. Subsequently, the nanofibers considerably reduced the hydrophobicity index and ergosterol content of the treated cells. Considering the challenges associated with the inhibition/disruption of fungal biofilm, the fabricated nanofibers prove their effectiveness against Candida biofilm. Therefore, nanocomposite-loaded nanofibers have emerged as potential materials that can control fungal colonization and could also promote healing.

Chiral Janus emulsions with gold nanocomposite for enantioselective catalysis

Chiral emulsions, with the chiral center of chiral-surfactant as the emulsifier, provide opportunities for selective catalysis and inorganic material synthesis. Janus emulsion draws researcher’s attention due to excellent multiple chambers, advanced structures and diverse interfaces. Chiral Janus emulsions are prepared with two immiscible oils of vegetable oil (VO)/dimethyl phthalate (DMP) and 2-(Perfluorooctyl)ethyl methacrylate (PFOEMA)/Ethoxylated trimethylolpropane triacrylate (ETPTA) as inner phases, by emulsified by chiral-surfactant [H-G-C16]FeCl4, in batch-scale by traditional vortex mixing. AuNPs as functional nanomaterials with peroxidase activity are then applied as active centers, adsorbing at the oil/water interface due to the electrostatic interactions between the positive charge of [H-G-C16]FeCl4 at Janus emulsion interfaces and the negative charge of AuNPs modified by SDS. Chiral Janus emulsion is endowed with catalytic activity and enantioselectivity. Catalytic results show two AuNPs@ Janus emulsions show better affinity to catalyze the oxidation of L-DOPA than D-DOPA. By investigating two AuNPs@ Janus emulsions with different inner phases, chiral Janus emulsion of AuNPs@ETPTA/PFOEMA/[H-G-C16]FeCl4(aq) has better catalytic activity and enantioselectivity than AuNPs@DMP/VO/[H-G-C16]FeCl4 (aq) because of the smaller droplets have larger interface areas could adsorb more [H-G-C16]FeCl4 molecules and AuNPs. The findings open an avenue in the production of chiral Janus emulsions with catalytic effect and enantioselectivity, which would push forward future applications in selective catalysis and inorganic material synthesis.

Facile engineering of aptamer-coupled silk fibroin encapsulated myogenic gold nanocomposites: investigation of antiproliferative activity and apoptosis induction.

Nanocomposites selectively induce cancer cell death, holding potential for precise liver cancer treatment breakthroughs. This study assessed the cytotoxicity of gold nanocomposites (Au NCs) enclosed within silk fibroin (SF), aptamer (Ap), and the myogenic Talaromyces purpureogenus (TP) against a human liver cancer cell (HepG2). The ultimate product, Ap-SF-TP@Au NCs, results from a three-step process. This process involves the myogenic synthesis of TP@Au NCs derived from TP mycelial extract, encapsulation of SF on TP@Au NCs (SF-TP@Au NCs), and the conjugation of Ap within SF-TP@Au NCs. The synthesized NCs are analyzed by various characteristic techniques. Ap-SF-TP@Au NCs induced potential cell death in HepG2 cells but exhibited no cytotoxicity in non-cancerous cells (NIH3T3). The morphological changes in cells were examined through various biochemical staining methods. Thus, Ap-SF-TP@Au NCs emerge as a promising nanocomposite for treating diverse cancer cells.

Electro-osmotic transport and thermal energy dynamics of tetra-hybrid nano fluid in complex peristaltic flows

BackgroundThis study explores the use of tetra-hybrid nanoparticles consisting of gold, silver, alumina, and titania nanocomposites dispersed in a non-Newtonian Casson fluid modelled as blood. The motivation lies in harnessing the synergistic optical, electrical, thermal, and physicochemical properties of the multimodal nanoscale assembly to advance electrokinetic pumping processes. ObjectivesThe study aims to computationally investigate the complex transport assisted by tailored gold, silver, alumina, and titania dioxide nanoparticles in the tetra-hybrid nanofluid, with potential applications in targeted drug delivery, hyperthermia cancer treatment, Lab-on-Chip devices, and miniaturized biosensors. MethodologyThe constructed streaming flow model examines the cumulative influence of viscous heating, Joule heating, conductive thermal, and external laser irradiation. Current simulations examine Casson flows with the integrated nanoparticles by modelling two- and three-dimensional conduits subject to transverse magnetohydrodynamics and localized laser irradiation. Key findingsThe solutions provide mathematical predictions and physical insights into the fully coupled velocity, temperature, concentration, and pressure gradient contours. Additional plots examining dimensionless analytes against pertinent profiles, combined with streamlined visualization, further elucidate the multifaceted transport and complex trapping patterns stemming from non-Newtonian rheology. Applications/implicationsThis multiscale examination reveals performance improvements realizable by leveraging biocompatible tetra-hybrid nanocomposites in electrokinetic flows vital for next-generation biomedical technologies.

Green synthesis of molecularly tailored chitosan-based gold and silver nanocomposite and their application in selective recognition of ciprofloxacin

Green synthesis of molecularly tailored chitosan-based gold and silver nanocomposite and their application in selective recognition of ciprofloxacin

Engineering of smart nanostructured lipid carriers encapsulated in gold nanocomposites and camptothecin for synergistic photothermal and chemotherapy treatment of ovarian cancer

Engineering of smart nanostructured lipid carriers encapsulated in gold nanocomposites and camptothecin for synergistic photothermal and chemotherapy treatment of ovarian cancer

Synthesis of Pseudostellaria heterophylla polysaccharide-gold nanocomposites and their antitumor effect through immunomodulation.

Polysaccharides from natural sources have an excellent immune function and low toxicity; however, their limitations such as short half-life and instability limit their sustained pharmacological activity. In this context, the combination of polysaccharides and nanotechnology have been developed to promote the stability and prolong the immune activities of polysaccharides. To synthesize and explore the antitumor effect and immunomodulatory activity of PHP-AuNPs. Polysaccharides extracted from Pseudostellaria heterophylla were used to synthesize gold nanocomposites (PHP-AuNPs), and their physicochemical properties and immunoregulatory effect in vitro and in vivo were analyzed. The PHP-AuNPs were green synthesized with high biosafety. PHP-AuNPs can activate macrophages in vitro and decrease the tumor weight and volume, whereas they increase the immune organ index in vivo. Besides, PHP-AuNPs showed a beneficial effect for maintaining the immune balance of CD4+/CD8+ T cells and modulating the release of cytokines such as TNF-α increase and IL-10 decrease in mice. All these results suggested that PHP-AuNPs exhibit a remarkable antitumor effect and stronger immunomodulatory activity than that of free PHP-1. RESEARCH HIGHLIGHTS: The P. heterophylla polysaccharide-gold nanocomposites (PHP-AuNPs) were synthesized and physicochemical properties were characterized. The cytotoxicity in vitro and immunomodulatory effects of PHP-AuNPs on macrophages were analyzed. The immune-antitumor effects in vivo of PHP-AuNPs have also been confirmed.

Merging of Bi-Modality of Ultrafast Laser Processing: Heating of Si/Au Nanocomposite Solutions with Controlled Chemical Content.

Ultrafast laser processing possesses unique outlooks for the synthesis of novel nanoarchitectures and their further applications in the field of life science. It allows not only the formation of multi-element nanostructures with tuneable performance but also provides various non-invasive laser-stimulated modalities. In this work, we employed ultrafast laser processing for the manufacturing of silicon-gold nanocomposites (Si/Au NCs) with the Au mass fraction variable from 15% (0.5 min ablation time) to 79% (10 min) which increased their plasmonic efficiency by six times and narrowed the bandgap from 1.55 eV to 1.23 eV. These nanostructures demonstrated a considerable fs laser-stimulated hyperthermia with a Au-dependent heating efficiency (~10-20 °C). The prepared surfactant-free colloidal solutions showed good chemical stability with a decrease (i) of zeta (ξ) potential (from -46 mV to -30 mV) and (ii) of the hydrodynamic size of the nanoparticles (from 104 nm to 52 nm) due to the increase in the laser ablation time from 0.5 min to 10 min. The electrical conductivity of NCs revealed a minimum value (~1.53 µS/cm) at 2 min ablation time while their increasing concentration was saturated (~1012 NPs/mL) at 7 min ablation duration. The formed NCs demonstrated a polycrystalline Au nature regardless of the laser ablation time accompanied with the coexistence of oxidized Au and oxidized Si as well as gold silicide phases at a shorter laser ablation time (<1 min) and the formation of a pristine Au at a longer irradiation. Our findings demonstrate the merged employment of ultrafast laser processing for the design of multi-element NCs with tuneable properties reveal efficient composition-sensitive photo-thermal therapy modality.

Functionalized gold nanoparticles coated with bacterial alginate and their antibacterial and anticancer activities

Abstract Gold nanoparticles (Au-NPs) have several uses for nanobiotechnologists because of their beneficial biomedical properties. Alginates have various biomedical and industrial applications. The aim of this study is to extract alginate from Azotobacter chroococcum, synthesize chemical Au-NPs (Ch/Au-NPs), and load the NPs with the extracted alginate to form Azotobacter alginate gold nanocomposites (Azto/Alg-Au-NCMs). The Ch/Au-NPs and Azto/Alg-Au-NCMs were characterized by UV-spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), zeta potential, and transmission electron microscopy (TEM). The anticancer activities were determined using the breast cancer cell line MCF-7, human lung cancer cell line H1299, and Vero cell line. The results obtained by UV-spectroscopy exhibited a surface plasmon resonance that was clearly noticeable at 530 nm, and the EDS analysis proved that gold was present in percentages of 50.11 and 28.08 in the Ch/Au-NPs and Azto/Alg-Au-NCMs, respectively. There were several similarities between the alginic acid and the alginate extracted from A. chroococcum, and small modifications were proved by FT-IR spectroscopy. Negative charges were shown by the zeta potential. Crystalline and cubic NPs were shown by XRD analysis and TEM. TGA demonstrated the purity of the Ch/Au-NPs and the existence of organic compounds in the Azto/Alg-Au-NCMs. Both the Ch/Au-NPs and Azto/Alg-Au-NCMs had antibacterial activities against Staphylococcus aureus ATCC 25923, Proteus mirabilis, Enterobacter sp., and Pseudomonas aeruginosa and possessed anticancer activities against MCF-7 and H1299.

Micro Mechanism Research of Photoacoustic Effect based on Gold Nanocomposites in Multiphysics Field

Micro Mechanism Research of Photoacoustic Effect based on Gold Nanocomposites in Multiphysics Field

Selective and precise solid phase extraction based on a magnetic cellulose gold nanocomposite followed by ICP-OES analysis for monitoring of total sulfur content in liquid fuels.

This study describes the synthesis and characterization of a magnetic cellulose gold nanocomposite (MCNC@Au) for magnetic solid phase (m-SPE) extraction of total sulfur content in liquid fuel samples followed by analysis using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The nanocomposite was prepared using an in situ co-precipitation method and characterization results from FTIR, P-XRD, TEM and SEM-EDX techniques confirmed the formation of the targeted nanocomposite. To achieve good extraction efficiency, the 2-level half-fractional factorial design and central composite design were used to investigate the most influential parameters of the proposed m-SPE method. The multivariate optimization results showed that efficient extraction was obtained when 27.5 mg sorbent mass, 35 minutes sorption time, 200 μL eluent volume and 8 min elution time were used. The optimal parameters resulted in excellent accuracy (98.8%), precision (1.7%), LOD (0.039 mg L-1), LOQ (0.129 mg L-1), MDL (0.014 μg g-1) and MQL (0.047 μg g-1). The optimized and validated m-SPE method was applied in real fuel oil samples, revealing a total sulfur content range of 13.20 ± 0.05-15.70 ± 0.02 μg g-1 for crude oil, 7.32 ± 0.01-9.12 ± 0.03 for μg g-1, 8.41 ± 0.02-9.15 ± 0.06 μg g-1 for gasoline and 9.10 ± 0.02 and 9.70 ± 0.04 μg g-1 for kerosene samples, sugesting high concentration levels of sulfur in crude oils. However, the obtained sulfur content levels are within the accepted standards in fuel oils, except for those of crude oil and kerosene samples. Therefore, the proposed m-SPE method followed by ICP-OES analysis has proven to be an alternative procedure for rapid and selective quantification of total sulfur in fuel samples.

Antitumor efficacy of synthesized Ag–Au nanocomposite loaded with PEG and ascorbic acid in human lung cancer stem cells

Lung cancer is the leading cause of mortality worldwide of which non-small cell lung carcinoma constitutes majority of the cases. High mortality is attributed to early metastasis, late diagnosis, ineffective treatment and tumor relapse. Chemotherapy and radiotherapy form the mainstay of its treatment. However, their associated side effects involving kidneys, nervous system, gastrointestinal tract, and liver further adds to dismal outcome. These disadvantages of conventional treatment can be circumvented by use of engineered nanoparticles for improved effectiveness with minimal side effects.In this study we have synthesized silver gold nanocomposite (Ag–Au NC) using polyethylene glycol and l-ascorbic acid as surfactant and reducing agent respectively. Synthesized nanocomposite was characterized by ultraviolet–visible absorption, dynamic light scattering, scanning and transmission electron microscopy. Compositional analysis was carried out by energy dispersive X-ray analysis and average pore diameter was estimated using Barrett-Joyner-Halenda method. In-silico molecular docking analysis of the synthesized NC against active regions of epidermal growth factor receptor revealed good binding energy. Subsequently, we investigated the effect of NC on growth and stem cell attributes of A549 lung cancer cells. Results showed that NC was effective in inhibiting A549 cell proliferation, induced DNA damage, G2/M phase arrest and apoptosis. Further, tumor cell migration and spheroid formation were also negatively affected. NC also enhanced reactive oxygen species generation and mitochondrial depolarization. In addition, the effect of NC on putative cancer stem cells in A549 cells was evaluated. We found that Ag–Au NC at IC50 targeted CD44, CD24, CD166, CD133 and CD326 positive cancer stem cells and induced apoptosis. CD166 positive cells were relatively resistance to apoptosis.Together our results demonstrate the anticancer efficacy of Ag–Au NC mediated by a mechanism involving cell cycle arrest and mitochondrial derangement.

Investigating the Antibacterial Activities of Graphene Oxide Loaded Spiky Gold Nanocomposites via Chitosan linker

The graphene oxide (GO) loaded spiky gold (AuNS) nanocomposites were prepared by electrostatic interaction between negatively-charged GO nanosheets and positively-charged AuNS by the assistance of chitosan as linker molecules. The AuNS/GO nanocomposites exhibit a red-shift in the extinction spectra and a reduction in the zeta potential compared to those of the pristine AuNS due to the presence of oxygen-containing functional groups in GO. The bactericidal analysis demonstrates that the incorporation of GO greatly enhances the intrinsic antibacterial activities of AuNS. Besides, the AuNS with smaller size exhibit better bactericidal efficiency compared to that of AuNS with bigger size. Upon light irradiation, the AuNS/GO with the absorption peak close to the wavelength of excitation light (900 vs. 904 nm) demonstrates a noticeable improvement in the bactericidal efficiency which is attributed to the plasmon-induced photothermal effect. All these results suggest that the AuNS/GO nanocomposites can work as a promising functional material for both intrinsic and plasmon-induced antibacterial materials.

New Au/chitosan nanocomposite modified carbon paste sensor for voltammetric detection of nicotine

A profoundly touchy voltammetric sensor for detection of nicotine (NIC) in urine and tobacco specimens has been developed in light of the boosted electrochemical response of NIC at gold and chitosan nanocomposite modified carbon paste electrode (ACMCPE). Material characterization techniques Scanning Electron Microscope and Energy Dispersive X-ray (SEM & EDX) were utilized to describe the ACMCPE surface material. The impedance spectroscopy technique (EIS), cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV) were employed to explore the electrochemical sensing of NIC at ACMCPE. The created sensor exhibits an exceptional electrochemical sensitivity to NIC in a universal Britton–Robinson (B-R) buffer solution with a pH range of 2.0 to 8.0. The sensor shows a linear response over NIC concentration ranges of 4.0–320.0 µM, with the detection limit (LOD) of 7.6 µM. The prepared sensor has been shown to be exceptionally viable in detecting NIC with amazing selectivity and reproducibility. We suggest it as a trustworthy and useful electrochemical sensor for NIC location.

Facile fabrication and antibacterial properties of chitosan/acrylamide/gold nanocomposite hydrogel incorporated with Chaetomium globosium extracts from Gingko biloba leaves

Microorganisms are a unique part of our ecosystem because they affect the survival of living organisms. Although pathogenic microorganisms could be detrimental to the plants, animals, and humans, beneficial microbes have provided significant improvement in the growth and development of living organisms. In this study, the fungus Chaetomium globosium was isolated from the medicinal tree Gingko biloba, and then incorporated into a polymerization system to fabricate chitosan/acrylamide/gold (CS/Am/Au) nanocomposite hydrogels. The as-prepared hydrogel displayed increased mechanical strength due to the reinforcement of Au (gold) nanocomposites within the hydrogel matrix. Also, the equilibrium pH responsive swelling rates of the hydrogels gradually increased as the pH increases due to partial acid and basic hydrolysis occurring in the hydrogel as well as formation of hydrogen bond. In addition, the hydrogel demonstrated promising antibacterial activities against selected gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacterial strains with an average MIC90 of 0.125 mg/mL at a dosage of 1.0 mg/L. The obtained results are quite promising towards resolving several health challenges and advancing the pharmaceutical industries.