Gold Nanocomposites Research Articles

Enhancing the photocatalytic activity of TiO2 and TiO2–SiO2 by coupling with graphene–gold nanocomposites

In the present paper, a novel composite Graphene–Gold (Gr–Au)/TiO2–SiO2 photocatalyst was synthesized and tested for the removal of methylene blue and rhodamine B in water solutions. First, Gr–Au nanoparticle composite was synthesized by simultaneous reduction and deposition of Au nanoparticles on Gr surface. The photodegradation of methylene blue and rhodamine B in aqueous solutions was studied using various photocatalysts, including neat TiO2–SiO2, Gr/TiO2–SiO2 and Gr–Au/TiO2–SiO2 composites. The Gr weight ratio in this research is 2% in the Gr/TiO2–SiO2 composites. Detailed characterization (field emission scanning electron microscope, Raman, Fourier transform infrared spectra and UV–vis absorbance spectroscopy) of such material was conducted. As a result, the uniform deposition of nanometer-sized Au NPs on the graphene sheets was observed. The Gr–Au/TiO2–SiO2 exhibited excellent photocatalytic efficiency because of the reduction of electron–hole recombination. The Gr2%–Au0.1%/TiO2–SiO2 composite had the highest photoactivity.

Anti-bacterial activity of gold nanocomposites as a new nanomaterial weapon to combat photogenic agents: recent advances and challenges.

Gold nanocomposites are being widely used in numerous biomedical applications owing to their excellent stability and miniaturization. Gold nanocomposites are notable because of their flexibility of functionalization and synthesis, ease of detection, and low toxicity. Cost-effectiveness, long-term stability, non-cytotoxicity, and biocompatibility are the main aspects of ideal nanocomposites. Antibacterial nanocomposites are being developed extensively in the food industry, environmental applications, and biological and medical devices. This review focuses on the applications of metal-based nanoparticles, mainly gold nanoparticles (AuNPs), as antibacterial agents in medical approaches. Additionally, the antibacterial mechanisms of AuNPs and their roles in fighting antibiotic-resistant microorganisms are highlighted in the present review.

Gold nanoparticle-guarded large-pore mesoporous silica nanocomposites for delivery and controlled release of cytochrome c

Efficient delivery of active proteins to specific cells and organs is one of the most important issues in medical applications. However, in most cases, proteins without appropriate carriers face numerous barriers when delivered to the target, due to their unsatisfied properties, such as poor stability, short half-life, and low membrane permeability. Herein, we have presented a large-pore mesoporous silica nanoparticle (LPMSN)-based protein delivery system. LPMSNs were obtained with ethyl acetate as a pore expander. A 2,3-dimethylmaleamic acid-containing silane coupling agent was modified on LPMSNs to provide pH-triggered charge reversal. After Cytochrome c (CC) was encapsulated in the large pores of LPMSNs, amino-terminated polyethylene glycol-modified gold nanoparticles (AuNPs) served as gateguards to cap the tunnels of LPMSNs and to avoid the leakage of CC. Above nanocomposites exhibited the capability to deliver active CC into cancer cells, charge reversal-induced protein release, as well as to initiate the apoptosis machinery of cancer cells in vitro. Importantly, the nanocomposites significantly inhibited tumor growth and extended survival rate without obvious side effects. This study provides a smart and efficient protein delivery platform with good safety profiles for efficacious tumor protein therapy in vivo.

Gold nanotheranostics: future emblem of cancer nanomedicine.

Cancer nanotheranostics aims at providing alternative approaches to traditional cancer diagnostics and therapies. In this context, plasmonic nanostructures especially gold nanostructures are intensely explored due to their tunable shape, size and surface plasmon resonance (SPR), better photothermal therapy (PTT) and photodynamic therapy (PDT) ability, effective contrast enhancing ability in Magnetic Resonance imaging (MRI) and Computed Tomography (CT) scan. Despite rapid breakthroughs in gold nanostructures based theranostics of cancer, the translation of gold nanostructures from bench side to human applications is still questionable. The major obstacles that have been facing by nanotheranostics are specific targeting, poor resolution and photoinstability during PTT etc. In this regard, various encouraging studies have been carried out recently to overcome few of these obstacles. Use of gold nanocomposites also overcomes the limitations of gold nanostructure probes and emerged as good nanotheranostic probe. Hence, the present article discusses the advances in gold nanostructures based cancer theranostics and mainly emphasizes on the importance of gold nanocomposites which have been designed to decipher the past questions and limitations of in vivo gold nanotheranostics.

Rational design of a FRET-based nanoprobe of gold-conjugated carbon dots for simultaneous monitoring and disruption of Pseudomonas aeruginosa biofilm through selective detection of virulence factor pyocyanin

Fluorescent nanoprobe for detection of pyocyanin to monitor Pseudomonas aeruginosa biofilm formation.

Core/shell structural ultra-small gold and amyloid peptide nanocomposites with effective bacterial surface adherence and enhanced antibacterial photothermal ablation

The exploration of ultra-small gold nanoparticles (Au NPs) (<5 ​nm) based photothermal nanoagent is important for antibacterial photothermal therapy due to their high biosafety. However, the ultra-small Au NPs usually have low absorption in near infrared (NIR) region, presenting poor NIR-based photothermal conversion. In the present work, a novel core/shell structural gold and amyloid peptide Aβ25-35 nanocomposites (Au@Aβ NCs) were constructed with ultra-small Au NPs (ca. 4.0 ​nm) as the core and Aβ25-35 oligomer as the shell (ca. 3 ​nm thickness) through the facile peptide templated chemical reduction method. The Au@Aβ NCs display enhanced NIR absorption and photothermal conversion efficiency as compared to pure Au NPs due to the extinction of Aβ shell. In addition, the Au@Aβ NCs can strongly adhere to the bacterial surfaces and aggregate together by virtue of the intrinsic self-assembly property of amyloid peptide, which facilitates the local photothermal ablation of bacteria. Consequently, the Au@Aβ NCs can fast and completely kill the pathogenic bacteria under NIR laser irradiation. This work provides an alternative strategy to prepare highly efficient ultra-small Au NPs based photothermal nanoagent for enhancing the antibacterial photothermal ablation.

A red light‐activable MnI(CO)3‐functionalized gold nanocomposite as the anticancer prodrug with theranostic potential

The controlled and target‐specific release of CO to a target site upon photoactivation has recently emerged as a promising tool for targeted anticancer activity. However, the present CO‐releasing molecules (CORMs) suffer several limitations, including poor delivery to the tumor site. In this study, we reported the synthesis, characterization, and caspase 3/7‐dependent apoptosis (IC50: 232 μg ml−1 or 29.03 nM) in A549 cells by manganese(I) carbonyl‐functionalized gold nanoparticles (1‐AuNPs) on dual photosensitization in red light (600–720 nm, 30 J cm−2). The 1‐AuNPs, however, remained nontoxic to A549 cells in the dark. The Mn(I)–CO complex (1) exhibited photocytotoxicity (IC50: 38.1 μM in red light; IC50: 88 μM in dark) as well. Dual photosensitization with red light leading to rapid, synergic CO release and singlet oxygen (1O2) generation were the principal mechanism for the photocytotoxicity, which was studied in detail. Photoactivated CO release resulted in TURN‐ON luminescence in A549 cells and renders the hybrid 1‐AuNPs an ideal, next‐generation nanotheranostic agent.

Horseradish Peroxidase-Immobilized Graphene Oxide-Chitosan Gold Nanocomposites as Highly Sensitive Electrochemical Biosensor for Detection of Hydrogen Peroxide

The generation of fast electrochemical response with high sensitivity is a significant parameter for enzymatic biosensors. However, establishing nanocomposite based modified electrode with fast electron shuttling between enzymes and the electrode surface for determination of hydrogen peroxide (H2O2) is highly challenging. Herein, the present work aims to develop second generation horseradish peroxidase (HRP) biosensors using Au nanochains dropcasted over electrochemically reduced graphene oxide-chitosan (ERGO-CHIT), a bio-nanocomposite film modified glassy carbon electrode (GCE) for reduction of H2O2 is demonstrated. The experimental conditions including effect of pH, loading of enzyme on the electrode surface and concentration of redox mediator as electrolyte were optimized. As a result, the HRP/Au/ERGO-CHIT/GCE electrode shows a larger enhancement in cathodic current signal with sharp peak response for reduction of H2O2, which can be attributed to the presence of Au nanochains on the modified electrode which improves the electron transfer between heme (Fe2+/Fe3+) center of enzymes on the electrode and the redox mediator in the electrolyte solution. The presence of HQ redox mediator in the electrolyte solution have provided stable peak response and offered more beneficiary in lowering the operating potential for the detection of H2O2 (−0.1 V), thereby reducing the influence from interference species. From the amperometric measurements, the HRP/Au/ERGO-CHIT/GCE modified electrode revealed high sensitivity (368.01 μA mM−1 cm−2) and possesses wide linear range (0.01 to 6.31 mM) which is mainly due to the high surface area and conductivity offered by Au nanochains which are located between ERGO and HRP. The resultant HRP/Au/ERGO-CHIT/GCE was found to possess good operational stability, high reproducibility, repeatability with low detection limits (4 μM), and thus it could be applicable for sensitive and rapid responsive detection of H2O2 in biological, clinical and environmental samples.

Development of a Novel Nanocomposite Based on Reduced Graphene Oxide/Chitosan/Au/ZnO and Electrochemical Sensor for Determination of Losartan

Background: Hypertension is a major risk for morbidity and mortality, while hypertension is associated with cardiovascular disease and organ damage. Recent research efforts have focused on the development of highly selective angiotensin receptor blockers. In which losartan (LOS) is considered as a new generation of an effective oral drug product against arterial hypertension. Therefore, the determination of drugs in biological fluids, pharmaceuticals (tablets), and wastewater is of critical importance for clinical applications, forensics, quality control, and environmental protection that call for the development of analytical methods. Many ranges of methods such as spectroscopic methods and chromatographic techniques have been developed to determine LOS in pharmaceutical formulations and biological fluids. However, there are crucial interference problems in these methods. For these reasons, more sensitive, desirable, portable, low-cost, simple, and selective nanocomposite-based sensors are needed in terms of health safety. Nanomaterials such as reduced graphene oxide, chitosan, and metal nanoparticles are used to improve the sensitivity in the development of electrochemical sensors. Objective: In this study, a novel reduced graphene oxide (RGO), chitosan (Chit), gold (Au), and zinc oxide (ZnO) nanocomposite (RGO/Chitosan/Au/ZnO) was synthesized and used to develop a sensitive and efficient electrochemical sensor for LOS detection. Methods: Modification of electrode by RGO/Chit/Au/ZnO nanocomposite was performed in four stages with GO (at -2.0 V for 150 s), Chitosan (at -3.0 V for 300 s), Au nanoparticles (at -0.4 V for 400 s), and Zn nanoflowers like (at -0.7 V for 1200 s). The RGO/Chitosan/Au/ZnO nanocomposite was characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR). Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) were used to detect LOS, and the influence of pH value, scan rate, accumulation potential, and time also losartan concentration on the performance of ZnO/Au/Chitosan/RGO/GCE were investigated. In order to investigate the selectivity of the modified electrode for the determination of LOS, the effect of possible interfering species was evaluated and showed that these species are not interferences. Also, the reproducibility of the modified electrode was investigated and implying that the RGO/Chit/Au/ZnO nanocomposite was highly reproducible. Results: The modified electrode was used as a sensor for the selective and sensitive determination of LOS with a detection limit of 0.073 μM over the dynamic linear range of 0.5μM to 18.0 μM. In addition, electrochemical oxidation of LOS was well recovered in pharmaceutical formulations. Conclusion: LOS is used to treat high blood pressure, taking into account the oxidation of this compound, the use of electrochemical based sensors, ideally suited to a specific chemical species, can be fully selectable and High-sensitivity answer is very important. In this study, the electrodes with RGO/Chit/Au/ZnO nanocomposite were modified by the electrochemical method. Nanocomposites were characterized by various methods such as FE-SEM, FT-IR, XRD, Raman, and XPS. The electrocatalytic activity of the modified electrode was then investigated for measuring LOS. According to the results of the modified electrode, high sensitivity, reproducibility, and selectivity have been shown to oxidize this composition.

Succinyl chitosan gold nanocomposite: Preparation, characterization, in vitro and in vivo anticandidal activity

Herein, we have successfully synthesized a novel N-Succinyl chitosan/gold nanocomposite (N-SuC/Au NC) using N-SuC and gold(III) chloride, and investigated the biocompatibility and antifungal activity. The synthesized N-SuC/Au NC was characterized by UV–visible spectroscopy, X-ray diffraction, field emission scanning electron microscope, and inductively coupled plasma atomic emission spectroscopy. The N-SuC/Au NC exhibited a strong inhibition effect towards pathogenic Candida albicans. Morphological analysis revealed the destruction of C. albicans cell membrane due to N-SuC/Au NC treatment. The in vitro and in vivo toxicity of N-SuC/Au NC was analyzed with HEK293T mammalian cells and zebrafish larvae, respectively. The synthesized N-SuC/Au NC demonstrated no cytotoxicity towards HEK293T cells up to 1200 μg/mL concentration. The survival rate of the zebrafish larvae at 120 hpf, was found as 100% up to 1200 μg/mL of N-SuC/Au NC exposure. The in vivo studies further confirmed the inhibitory effects of N-SuC/Au NC on the formation of C. albicans hyphae in infected zebrafish muscle tissue.

A Novel Electrochemical DNA Biosensor Based on a Gold Nanoparticles-Reduced Graphene Oxide-Polypyrrole Nanocomposite to Detect Human T-Lymphotropic Virus-1

An electrochemical DNA biosensor for the Human T-Lymphotropic Virus-1 (HTLV-1) detection was developed using differential pulse voltammetry (DPV). For this purpose, single-strand DNA (ssDNA) probe was immobilized on the screen-printed carbon electrode (SPCE) modified with nanocomposite of reduced graphene oxide, polypyrrole, and gold nanoparticles (rGO-PPy-AuNPs). Then, the hybridization with the target DNA was studied by measuring the electrochemical oxidation response of the anthraquinone-2-sulfonic acid sodium salt monohydrate (AQMS). The calibration curve displayed a linear range between $10^{-15}$ and $10^{-7}$ mol/L, with a detection limit of 40 atto-molar towards HTLV-1 DNA concentrations. This DNA sensing platform was successfully applied to detect the DNA extracted from Peripheral Blood Mononuclear Cells (PBMC) sample. Also, the specificity of the proposed biosensor was investigated by a positive sample of HTLV-1, a positive sample of HSV-1 (non-complementary sample), a mix-sample (HTLV-1 and HSV-1) and negative sample. Moreover, the relative standard deviation (RSD) of repeatability and reproducibility tests was 2.8 % and 4.3 % respectively, that it is less than 20% and demonstrates the good reusability and stability of the proposed biosensor.

Design of a point-of-care device for electrochemical detection of P.vivax infected-malaria using antibody functionalized rGO-gold nanocomposite

A point-of-care electrochemical “Tri-inlet” device integrated with an electrode that acts as a sensor is developed for early-stage diagnosis of Plasmodium vivax (Pv)-infected malaria in a human patient’s whole blood sample. The electrode is prepared in a step-wise manner involving a synthesis of rGO-based gold nanocomposite (Au-rGO) followed by conjugation with P.vivax specific antibody (merozoite surface protein-1, MSP1) and deposition of the antibody functionalized nanocomposite (Au-rGO-MSP1) over carbon strip. The crucial directional conjugation of the antibody to the nanocomposite is achieved through ethylenediamine (EDA) as a spacer for sensitive detection of the Pv-infected RBCs (Pv-iRBCs) in vivax malaria diagnosis. The Au-rGO-MSP1 based electrode (sensor) showed a decrease in peak-current density and an increase in charge-transfer resistance (Rct) as electrical signals in ferro/ferricyanide solution system due to the interaction between MSP1 antibody of the electrode and Pv-iRBCs. The Rct values increased proportionally with the number of iRBCs and varied linearly for cell concentration (R2 = 0.990). The performance analysis with the patient’s whole blood sample showed good sensitivity and selectivity with a detection limit of ∼40 vivax infected RBCs (Pv-iRBCs)/ 10 μL blood sample in 5 minutes which is comparable or even better than the most of the commercially available malaria kit. The present electrochemical approach demonstrated the proof-of-concept for designing a new disposable type sensor kit that could be easily used for early onsite detection of Plasmodium vivax-infected malaria.

Polychlorinated Biphenyl Electrochemical Aptasensor Based on a Diamond-Gold Nanocomposite to Realize a Sub-Femtomolar Detection Limit.

Polychlorinated biphenyls (PCBs) with high toxicity, low lethal dose, and bioaccumulation have been inhibited for application in wide fields, and a highly efficient trace detection is thus greatly desirable. In this study, we produce dense Au-nanoparticles by twice sputtering and twice annealing (T-Au-NPs) on boron-doped diamond (BDD). The successful formation of T-Au-NPs/BDD nanocomposites was confirmed by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy analysis. Based on T-Au-NPs/BDD, an electronic biosensor with aptamers is fabricated to detect trace polychlorinated biphenyl-77 (PCB-77) by electrochemical impedance. A good linear relationship in the range of femtomolar to micromolar and significantly low detection limit of sub-femtomolar level (0.32 fM) are realized based on the biosensor. The emphasis of this research lies in the key role of the diamond substrate in the biosensor. It is demonstrated that the biosensor has excellent sensitivity, specificity, stability, and recyclability, which are favorable for detecting the trace PCB-77 molecule. It is attributed to the important effect presented by the BDD substrate and the synergistic influence of T-Au-NPs combined with aptamers.

Improvement the catalytic activity of activated Au/GO–CeO2 nanocatalysts by facile ball milling–hydrothermal methods for PROX operation

Gold-based nanocatalysts have proved to be an appropriate candidate for the selective preferential CO oxidation (PROX) in H2-containing atmosphere. Effectiveness of small gold nanoparticles in the presence of immobilized on GO–CeO2 nanocomposites was investigated by a range of ball milling conditions for the PROX reaction. First, GO–CeO2 nanocomposites were fabricated using the combination of ball milling and hydrothermal methods, and then, the gold nanocomposites were activated at 400 ± 2 °C for 4 h in Ar atmosphere. Next, Au/GO–CeO2 catalysts were synthesized, and after that, the gold nanocontents calcined at 400 ± 2 °C in Ar gas during 4 h. The catalytic activity and selectivity of activated gold catalysts (Au/GO–CeO2) were studied for the preferential CO oxidation at optimized conditions from the ambient temperature to 175 ± 2 °C. The gas and vapor phase components were analyzed by a Fourier Transform Infrared Spectroscopy. The effects of ball mill’s parameters, such as milling time, bead amounts, loading percentage, and milling temperatures, on the catalytic activity and selectivity of gold catalysts were investigated. Under relatively optimized conditions, the results showed the high conversion (C%: 97) and selectivity (S%: 92) for the gold nanocatalysts at 150 °C reaction time towards CO2 as the main product when the Au/GO–CeO2 nanocatalysts were synthesized by the use of 12% of GO solution with 90 zirconia oxide balls at 70 °C for 8 h of the ball milling condition.

Immuno biocompatibility and anti-quorum sensing activities of chitosan-gum acacia gold nanocomposite (CS-GA-AuNC) against Pseudomonas aeruginosa drug-resistant pathogen

In this study, an eco-friendly green route strategy was adopted for the synthesis of highly stable, biocompatible polymer-polymer- metal-based composite with high potential anti-bacterial applications. The composite was prepared by modified ionic gelation of Chitosan –gum acacia copolymer with gold nanoparticles (Cs-GA-AuNC). Structural, functional characteristics of the synthesised nanocomposite were studied by spectroscopic, electron microscopic and X-ray diffraction (XRD) studies which reveal functionalised polymers coupled with the gold nanoparticles to form electron core dense nanostructural composite material with notable nanoarchitecture. The synthesised nanocomposite was evaluated for anti-quorum sensing activity against human pathogenic bacterial strain Pseudomonas aeruginosa by measuring the expression of Las R. Nanocomposite treatment brought about drastic reduction of Las R gene expression followed by the remarkable impact on Las R gene-based virulence factors like biofilm formation, pyocyanin production, swarming motility, and total proteolytic activity. Biocompatibility of the composite was tested on Raw cells 246.7 –murine macrophage cell line/The nanocomposite was not inducing any sign of toxicity on the tested Raw cells 246.7 by exhibiting maximum cell viability, lower level of ROS generation and reduced nitride concentration which revealed the noteworthy biocompatibility of synthesised nanocomposite. This selective biological activity shown by the nanocomposite might find its application in the drug delivery for precision medicine.

Polyaniline coated gold-aryl nanoparticles: Electrochemical synthesis and efficiency in methylene blue dye removal

Synthesis of gold-carbon σ-bond nanoparticles was achieved by the electrochemical reduction of aryldiazonium tetrachloroaurate(III) salt [HOOC-4-C6H4N≡N]AuCl4 in the presence of polyaniline (PANI) emeraldine salt. The in situ electrochemical synthesis of PANI coated Au−COOH NPs was efficient in KNO3 supporting electrolyte at different potential values using two electrodes cell. The deposition potential was determined from the cyclic voltammetry study of aryldiazonium gold(III) salt. The nanocomposites were characterized with thermal gravimetric analysis (TGA), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The multi-branched nanoparticles display the strongest diffraction peak in the direction of (111) which implies the deposition occurred preferentially along this highly energetic facet. The results concluded the thermal stability of the gold nanocomposites and the gold percentage in the range 5−23 wt.%. Selected area electron diffraction pattern (SAED) analysis displayed typical rings of face centered cubic structure of crystalline gold(0) nanoparticles. Raman analysis supported the completeness of the reduction of the aryldiazonium cation and gold(III) supported by the absence of the diazonium and [AuCl4]− vibrations and the presence of the gold-carbon peak. Emeraldine coated gold-carbon nanoparticles soaked to nanosand showed high removal percentage for methylene blue. The adsorption kinetics follows a pseudo-second order. It may indicate that the prepared materials could be used to remove synthetic dyes in textile wastewater treatment.

Effect of HIF-1αsiRNA-linked AuNRs on radiotherapy of nasopharyngeal carcinoma

The radiation sensitivity of tumor cells is closely related to tumor cell hypoxia. Hypoxia-inducible factor-1α (HIF-1α) is considered a key transcription factor which regulates the sensitivity of hypoxic tumor cells to radiotherapy. On the other hand, some studies have shown that gold nanomaterials improve radiation sensitivity. However, studies on the effect of gold nanomaterials carrying HIF-1αsiRNA on tumor radiotherapy, and the underlying mechanisms are limited. Thus, the present study was aimed at investigating the effect of gold nanocomposites (AuNRs) carrying HIF-1αsiRNA (AuNRs-HIF-1αsiRNA) on the radiation sensitivity of nasopharyngeal carcinoma (NPC) hypoxia cells. The effect of AuNRs-HIF-1αsiRNA on radiation sensitivity of hypoxic NPC cells was determined under X-ray irradiation. The results showed that Au-HIF-1αsiRNA improved the radio-sensitivity of NPC tumor. Thus, this study has demonstrated that gold nanomaterials carrying HIF-1αsiRNA effectively increased the radio-sensitivity of hypoxic tumor, thereby improving the effect of radiotherapy on NPC cells.

Green Synthesis, Characterization and Antibacterial Study of Ag-Au Bimetallic Nanocomposite using Tea Powder Extract

Synthesis of metal nanoparticles using plant extracts is attracted much to the recent researchers due to its simplicity, which integrates chemical technology. Special attention is given to the green synthesis of nanoparticles by easily available plants with an eco-friendly system compared to other conventional methods. Silver-Gold nanocomposite (Ag-Au NCp’s) is synthesized by bi reduction of silver nitrate and gold chloride. These metal salts are simultaneously reduced by tea extract to form respective silver and gold nanocomposite. The structure and morphology of as-prepared Ag-Au NCp’s sample were characterized by employing powder X-ray diffraction (XRD) tool and by Scanning Electron Micrograph (SEM) tool, respectively. Fourier Transform Infrared (FTIR) spectral study was undertaken to know the bonding in the prepared silver sample. Morphology and particle size of the above composite was studied by the Transmission electron microscope (TEM) tool. Energy-dispersive X-ray analysis (EDX) study was undertaken to know the formation of Ag-Au NCp’s. Antibacterial activity study is undertaken to know its biological behavior.

Hydrophobically modified sodium alginate conjugated plasmonic magnetic nanocomposites for drug delivery & magnetic resonance imaging

We report the synthesis of multifunctional plasmonic magnetic nanocomposites of iron oxide and gold. Sodium alginate is thiolated and grafted with hydrophobic amine-terminated poly butyl methacrylate (PBMA-NH2). The nanocomposites are conjugated with PBMA-NH2 grafted thiolated sodium alginate (TSA) for dispersion stability and enhancing the encapsulation efficiency (EE) of anti-cancer drugs. The nanocomposites are physico-chemically characterized and their contrast properties for magnetic resonance imaging (MRI) in phantom agarose gel are evaluated. The nanocomposites exhibit a reduction in transverse relaxation time (T2) from 94 milliseconds to 5.8 milliseconds on increasing the concentration of the nanocomposites (corresponding to 0.5 µg/mL to 50 µg/mL of iron). Paclitaxel (PTX) is encapsulated in the nanocomposites coated with hydrophobically modified TSA and an increment of 9% in EE is achieved as compared to the nanocomposites coated with TSA alone. PTX loaded nanocomposites offer higher efficacy (∼10 %) as compared to PTX on PLC/PRF/5 human hepatocellular carcinoma cells.

Determination of Cysteine by Diffuse Reflectance Spectroscopy by Its Influence on the Formation of Gold Nanocomposites Based on Polyurethane Foam

A method is proposed for the determination of cysteine in an aqueous solution by its effect on the formation of gold nanoparticles on the surface of polyurethane foams. The method is based on the interaction of in situ formed gold nanoparticles with cysteine, which results in their stabilization in solution and in a decrease in the color intensity of the nanocomposite detected by diffuse reflectance spectroscopy. The effect of the concentration of the precursor, aurichlorohydric acid, contact time of phases, and the pH of the solution on the sensitivity of cysteine determination is studied. Under the selected conditions, the limit of detection for cysteine was 0.36 μg/mL. A possibility of using the proposed method for the determination of cysteine in brewer’s yeast is demonstrated.