Stabilized Gold Nanoparticles Research Articles

Functionalized Triangular Carbon Quantum Dot Stabilized Gold Nanoparticles Decorated Boron Nitride Nanosheets Interfaced for Electrochemical Detection of Cardiac Troponin T.

The fast, and highly sensitive estimation of cardiac troponin T (cTnT) is crucial for the early identification of acute myocardial infarction (AMI). The electrochemical immunoassay-based (EIB) sensors are highly promising for this purpose, as they offer precise measurements and can be directly assessed in intricate matrices, including blood. To increase sensitivity, EIB sensors use nanomaterials or amplification processes, which can be laborious to develop. With this, we develop an electrochemical immunosensor for the sensitive detection of cardiac troponin T (cTnT). The sensing platform is composed of functionalized triangular carbon quantum dots stabilized gold nanoparticles which are integrated with boron nitride nanosheets (caf-TCQDs@AuNPs on HO-BNNS). Ferrocene carboxylic acid (Fc-COOH) serves as the signal label. The composite was developed and examined using several techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry, and chronocoulometry. The caf-TCQDs@AuNPs supported on HO-BNNS, have a large surface area and excellent electrical conductivity, and serve as an effective platform for the immobilization of anti-cTnT monoclonal antibodies via carbodiimide coupling. The Fc-COOH, functioning as a signal label through the oxidation process, was integrated with caf-TCQDs@AuNPs on the HO-BNNS platform to establish an electrochemical immunosensor for the detection of cTnT. The electrochemical immunosensor demonstrated excellent performance for the determination of cTnT under optimal conditions, exhibiting a linearity range spanning from 0.0001 to 100 ng mL-1, accompanied by a low detection limit of 0.0013 ng mL-1. Notably, the immunosensor revealed high specificity, as well as excellent levels of reproducibility and reliability for the examination of human serum samples.

Pillar[5]arene stabilized gold nanoparticles for the enhanced light-triggered nitric oxide release with antibacterial and antibiofilm activities

The reactivity of guests confined in well-defined host cavities act significantly different from that in bulk systems. In this work, pillar[5]arene not only works as a stabilizer for the fabrication of gold nanoparticles, but also act as an accelerator for the enhanced photo-triggered release of gaseous nitric oxide (NO) from encapsulated NO donor. The host–guest complex can dramatically improve the photoactivity of loaded guest molecule to generate antibacterial NO molecules through the confinement effect of pillar[5]arene cavity. The synergistic photo-triggered localized NO release and photo-thermal effect of host–guest complex demonstrated impressive antibacterial behaviors against Gram-negative bacterial strain Escherichia coli, Gram-positive bacterial strain Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. Moreover, this biocompatible photo-responsive complex can also inhibit bacterial biofilm formation and disrupt the pre-existing biofilms.

Preparation and Complex Characterisation of Stabilised Gold Nanoparticles: Biodistribution and Application for High Resolution In Vivo Imaging

The Turkevich method was optimized to prepare gold nanoparticles (AuNP) stabilized by polyethyleneglycol (PEG) for µCT. Using various independent modalities, we thoroughly characterized the optimized PEG-AuNPs. Here, we show that PEG-AuNPs are retained in the blood and provide a high contrast in the high-resolution µCT imaging of blood vessels and inner organs. The biodistribution is characterized by prolonged circulation in the blood and accumulation in the liver, spleen and skin. The accumulation of AuNP in the skin resulted in the blue discoloration of eyes and the whole skin. In vitro experiments using a leukemic monocyte THP-1 cell line model expressing high levels of NLRP3 demonstrated that the NLRP3inflammasome was not activated by PEG AuNP. Over 9 months, the mice were scanned by µCT and were in good health. Scans in mice using PEG-stabilized AuNPs in this study were sharper, with a higher contrast, when compared to a commercial contrasting agent at the same dose. The PEG-AuNPs were morphologically and chemically stable for at least two years when stored in the refrigerator.

Stabilization of gold nanoparticles in a transparent polymer while maintaining the capabilities of a colorimetric glucose sensor

We suggest optical sensor systems based on the gold nanoparticles embedded within the polymethacrylate matrix for dual-signal spectrophotometric and colorimetric approaches can be used for the determination of glucose in the range of 0.1–0.8 mM and 0.3–0.8 mM with the detection limits of 0.06 mM and 0.1 mM, correspondingly. We studied the conditions of interaction between the gold nanoparticles, iodide and glucose by evaluating the influence of such factors as the contact time, pH and the analyte concentration upon the analytical signal.

Particle size and band gap evaluation of green gold nanoparticles (AuNPs) with potential applications

Abstract The present study was aimed towards green synthesis of gold nanoparticles (AuNPs) using fungal strain (SGSK-7) with assessment of their size using different techniques viz., X-ray diffractormeter, Dynamic light scattering, Atomic force microscopy, FE-Scanning Electron Microscopy and Fourier transform Infrared Spectroscopy. The intense characteristic diffraction peaks at angle 2Ѳ (38.13˚) presented the crystalline nature of the reduced gold solution and calculation of crystalline size (12 nm) using Scherer’s equation further confirmed synthesis of gold nanoparticles while dynamic light scattering analysis indicated the particle size range of gold nanoparticles between 2 nm to 50 nm. Field Emission Scanning Electron Microscopic (FESEM) and Atomic Force Microscopy (AFM) analysis of extracellular gold nanoparticles depicts spherical shape of AuNPs of approximately 40 nm. Fourier transform Infrared (FTIR) Spectroscopy depicted the presence of the gold nanoparticles along with the other biomolecules secreted by fungus which plays vital role in reduction, capping and stabilization of gold nanoparticles. Energy dispersive X-ray, mapping analysis, Zeta potential and UV-Vis spectrophotometery analysis further confirmed the presence and stability of gold nanoparticles, respectively. Zeta potential of gold nanoparticles leads to conclude the neutral nature (-10 mV to 10mV) of the particles. The UV-Visible spectrophotometeric analysis also confirmed the formation of gold nanoparticles with an absorption peak at 547 nm. On the basis of UV-Visible spectra the optical band gap of 2.44 eV is examined. The phylogenetic relatedness of SGSK-7 revealed 99% homology with Aspergillus tamari after sequencing of the ITS region followed by BLAST.

UV light promoted dihydrolipoic acid and its alanine derivative directed rapid synthesis of stable gold nanoparticles and their catalytic activity

In general, colloidal gold nanoparticles (AuNPs) have been synthesized in heated or boiling water containing HAuCl4 precursor with sodium citrate as reducing stabilizing reagent. Although temperature plays a driving for synthesis of AuNPs, elevated temperature in thermal reduction method causes aggregation of the AuNPs. The preferential, rapid and strong binding of dihydro-lipoic acid and its derivatives on surface of AuNPs via thiol − Au chemistry promote the production of very stable AuNPs. In this study, we have developed citric acid (CA), dihydrolipoic acid (DHLA) and DHLA-Alanine (DHLA-Ala) directed rapid synthesis of ultra-stable AuNPs, DHLA@AuNPs and DHLA-Ala@AuNPs, under the UV (311 nm) irradiation at room temperature (RT: 25 °C) in around 10 min (min). CA is used as a potential reducing agent to expedite both reduction of Au3+ ion and AuNP formation, DHLA and DHLA-Ala act as stabilizing agents by replacing CA molecules on surface of AuNPs in order to produce quite stable AuNP. It is worthy to mention that reduction of Au3+ ion, formation and surface stabilization of AuNPs are consequently occurred in one step. We also investigated how experimental parameters including reaction time and temperature, pH of reaction solution, affect formation of the AuNPs. The effects of salt concentration and storage temperature were studied to show stability of the AuNPs. The synthesized DHLA@AuNPs and DHLA-Alanine@AuNPs were characterized via UV-Vis spectrophotometer (UV-Vis), scanning transmission electron microscope (STEM), dynamic light scattering (DLS) and Zeta potential (ZT) devices. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was efficiently catalyzed by the AuNPs in the presence of sodium borohydride in aqueous solution.

Synthesis and Characterization of Acacia-Stabilized Doxorubicin-Loaded Gold Nanoparticles for Breast Cancer Therapy.

The targeted delivery of drugs is vital in breast cancer treatment due to its ability to produce long-lasting therapeutic effects with minimal side effects. This study reports the successful development of doxorubicin hydrochloride (DOX)-loaded colloidal gold nanoparticles stabilized with acacia gum (AG). Optimization studies varied AG concentrations (0.25% to 3% w/v) to determine optimal conditions for nanoparticle synthesis. The resulting acacia stabilized gold nanoparticles (AGNPs) were characterized using various techniques including high-resolution transmission electron microscopy (HR-TEM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), and selected area electron diffraction (SAED). In vitro drug release studies demonstrated a higher release rate of DOX in sodium acetate buffer (pH 5.0) compared to phosphate buffer saline (pH 7.4), suggesting an enhanced therapeutic efficacy in acidic tumor environments. Cytotoxicity of DOX-AGNPs and free DOX was assessed in human breast cancer cells (MDA-MB-231). The DOX-AGNPs exhibited significantly greater cytotoxicity, indicating enhanced efficacy in targeting cancer cells. This enhancement suggests that adsorbing DOX on the surface of gold nanoparticles can improve drug delivery and effectiveness, potentially reducing side effects compared to pure DOX and traditional delivery methods. Stability tests conducted over six months at 25±1°C showed significant changes in particle size and PDI, suggesting limited stability under these conditions. Overall, the acacia-stabilized gold nanoparticles synthesized in this study exhibit promising characteristics for drug delivery applications, particularly in cancer therapy, with effective drug loading, controlled release, and favorable physicochemical properties.

Advanced Electrochemical Detection of 2,4-dichlorophenol in Water with Molecularly Imprinted Chitosan Stabilized Gold Nanoparticles

2,4-Dichlorophenol (2,4-DCP) is a hazardous chemical that can be passed down to offspring. Because 2,4-DCP degrades slowly and can be passed down to future generations, it’s a pesticide that needs to be continuously monitored and managed. With the use of chitosan-stabilized AuNPs on a glassy carbon electrode and the molecular imprinting technique, an effective electrochemical sensor has been built for the selective determination of 2,4-DCP in different aqueous samples. The analyte’s electroactive surface area and number of interaction sites are both increased by the AuNPs. The formulated AuNPs were characterized using several material characterization techniques. Molecularly imprinted nanomaterials provided the selectivity against other interfering chlorophenols. With a detection limit of 6.33 nM and a broad linear dynamic range of 21.09 to 310 nM, 2,4-DCP was found using differential pulse voltammetry. Without interference from structural analogs, the sensor was effectively evaluated in a variety of contaminated water samples.

Multifunctional SERS Substrate for Simultaneous Detection of Multiple Contaminants and Photothermal Removal of Pathogenic Bacteria.

In this work, a boric-acid-modified Fe3O4@Au@BA-MOF composite material as a multifunctional SERS substrate was ingeniously constructed for detecting both pathogens and antibiotics as well as photothermally inactivating the pathogens. Through improving the dispersity and stability of gold nanoparticles (Au NPs), leveraging the specificity of boric acid (BA) groups in recognizing cis-diol structures, and the ability of SERS technology to provide unique fingerprint spectra of targets, the sensitive and stable detection of pathogens and antibiotics was achieved. Compared with Au NPs and Fe3O4@Au, the SERS enhancement factor of Fe3O4@Au@BA-MOF was 4.31 × 106, which was about 400 times and 16 times higher than the former two, respectively. Among the existing work, the limit of detection for pathogens was lower or comparable, and it exhibited good stability, maintaining consistent performance for 23 days. Additionally, this substrate achieved efficient photothermal inactivation of pathogens under both near-infrared light and natural light excitation. Within 8 min of near-infrared light irradiation, the bactericidal rates for Staphylococcus aureus and Escherichia coli reach 100% and 99.3%, respectively.

One-Pot Synthesis of Tannic Acid-Au Nanoparticles for the Colorimetric Determination of Hydrogen Peroxide and Glucose.

This study introduces a novel one-pot method employing tannic acid (TA) to synthesize stable gold nanoparticles (TA-AuNPs), which are characterized using transmission electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. We apply these TA-AuNPs in a newly developed colorimetric assay for hydrogen peroxide (H2O2) detection that utilizes the oxidation of iodide (I-) on TA-AuNPs, leading to a detectable yellow color change in the solution. The reaction kinetics are captured by the rate equation R = 0.217[KI]0.61[H2O2]0.69. The possible sensing mechanism was proposed through density functional theory calculations. At the optimum conditions, the proposed TA-AuNPs/I- system demonstrated a linear relationship between H2O2 concentration and absorbance intensity (λ = 350 nm) and achieved a limit of detection (LOD) of 7.33 μM. Furthermore, we expand the utility of this approach to glucose detection by integrating glucose oxidase into the system, resulting in a LOD of 10.0 μM. Application of this method to actual urine samples yielded spiked recovery rates ranging from 96.6-102.0% and relative standard deviations between 3.00-8.34%, underscoring its efficacy and potential for real-world bioanalytical challenges.

Modified frankincense resin stabilized gold nanoparticles for enhanced antioxidant and synergetic activity in in-vitro anticancer studies

For the first time, Frankincense resin (FR) has been carboxymethylated to produce CMFR – AuNPs and the conjugate was utilized for the Doxorubicin drug loading. The carboxymethylation of the carboxylic, phenolic, and hydroxyl functional groups of FR has been developed into carboxymethylated Frankincense resin (CMFR). A novel CMFR-AuNPs was synthesized using the developed CMFR as a stabilizing and reducing agent. The antibacterial, antioxidant, and in-vitro anticancer activities were investigated by using CMFR-AuNPs and CMFR – AuNPs@DOX. CMFR-AuNPs demonstrated antioxidative properties by quenching DPPH radicals effectively. CMFR-AuNPs and DOX@CMFR-AuNPs demonstrated strong antibacterial activity against K. pneumoniae, S. aureus, B. subtilis, and E. coli. The cell viability was tested for CMFR -AuNPs at various concentrations of Dox-loaded CMFR -AuNPs (CMFR-AuNPs + Dox1, CMFR-AuNPs + Dox 2, & CMFR-AuNPs + Dox 3). The highest inhibition was observed on MCF-7 and HeLa cell lines using CMFR-AuNPs + Dox 3, respectively. Various techniques such as UV, FTIR, TGA, XRD, SEM, EDAX and TEM were used to characterize the designed CMFR and CMFR-AuNPs. After carboxy methylation, the amorphous nature of FR changed to crystallinity, as reflected in the XRD spectra. The XRD spectrum of the CMFR- AuNPs showed FCC structure due to the involvement of hydroxyl and carboxylic functional groups of CMFR strongly bound with the AuNPs. TGA results revealed that the CMFR is thermally more stable than FR. TEM revealed that CMFR - AuNPs were well dispersed, spherical, and hexagonal with an average diameter of 7 to 10 nm, while the size of doxorubicin loaded (DOX@CMFR-AuNPs) AuNPs was 11 to 13 nm. Green CMFR-AuNPs have the potential to enhance the drug loading and anticancer efficacy of drugs.

Novel approach for green synthesis of stable gold nanoparticles with dried turmeric root extract: investigations on sensor and catalytic applications.

In this study, we present the synthesis of gold nanoparticles (AuNPs) using a completely green synthesis method without the use of any additional functionalizing agent, except dried turmeric root extract. The significant synthesis parameters were optimized, and the applicability of AuNPs was investigated in areas such as plasmonic and fluorescent sensing of aluminum (Al3⁺) and chromium (Cr3⁺) ions, reduction of 4-nitrophenol (4-NP), and degradation of methylene blue (MB) and methyl orange (MO) dyes. Characterization studies were performed using UV-Vis spectroscopy, TEM, FTIR, and XRD, revealing that the AuNPs predominantly had a spherical morphology and a very small particle size of 8.5 nm, with stability maintained up to 120 days. The developed AuNP-based plasmonic sensors relied on aggregation-induced decreases in absorption, along with a red shift in the spectra. Fluorescence sensing demonstrated a linear increase in intensity with increasing concentrations of Al3⁺ and Cr3⁺, with detection limits of 0.83 and 1.19 nM, respectively. The catalytic activities of AuNPs were tested in reducing 4-NP and degradations of MB and MO dyes (binary system) in tap water and wastewater, with the reactions following pseudo-first-order kinetics. This study highlights the potential of AuNPs synthesized from turmeric roots for various environmental and sensing applications.

Green Synthesis Gold Nanoparticles using Bioreductant Red Shoot Leaf Extract (Syzygium myrtifolium Walp.) and Activity as Antioxidant

Gold nanoparticles (AuNPs) are small-sized materials important in various commercial and industrial applications. Several methods have been developed to synthesise AuNPs. This study was conducted by synthesizing AuNPs using HAuCl4 as a precursor and red shoot leaf extract as a bioreductor. The concentrations of AuNPs used were 20, 10, 5, and 2.5 ppm. Characterization of gold nanoparticles at a concentration of 20 ppm was carried out using a UV-Vis spectrophotometer to measure the maximum wavelength and Transmission Electron Microscopy (TEM) to determine particle size. Antioxidant activity at 20, 10, 5, and 2.5 ppm was determined by measuring free radical capture activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. The results showed that gold nanoparticles had a maximum wavelength of 530 nm with a ruby red color and an average particle size of 14.907 nm. The synthesized AuNPs showed high antioxidant activity: 99.6% (20 ppm), 98.9% (10 ppm), 96.7% (5 ppm), and 91.0% (2.5 ppm), indicating that higher concentrations of AuNPs resulted in more significant free radical scavenging. This study successfully synthesized gold nanoparticles using red shoot leaf extract as an environmentally friendly bioreduction. The resulting nanoparticles have a nanometer particle size with very high antioxidant activity, especially at a concentration of 20 ppm. The method used in this study offers a more environmentally friendly alternative for synthesizing gold nanoparticles, which previously often used hazardous chemicals. The use of red shoot leaf extract as a bioreductor has not been widely reported in the literature, thus providing a new contribution to green nanotechnology. Further research is recommended to explore the potential applications of gold nanoparticles synthesized by this method in medical and other industrial fields. In addition, additional studies are needed to optimize the synthesis conditions and more in-depth characterization of the stability and toxicity of gold nanoparticles in practical applications.

Stability and SERS signal strength of laser-generated gold, silver, and bimetallic nanoparticles at different KCl concentrations

Noble metal nanoparticles, specifically gold and silver, are extensively utilized in sensors, catalysts, surface-enhanced Raman scattering (SERS), and optical-electronic components due to their unique localized surface plasmon resonance (LSPR) properties. The production of these nanoparticles involves various methods, but among the environmentally friendly approaches, laser ablation stands out as it eliminates the need for toxic chemicals during purification. However, nanoparticle aggregation poses a challenge in laser ablation, necessitating the addition of extra materials that contaminate the otherwise clean process. In this study, we investigate the effectiveness of a biocompatible material, potassium chloride (KCl), in preventing particle aggregation. Although salt is known to trigger aggregation, we observed that certain concentrations of KCl can slow down this process. Over an eight-week period, we examined the aggregation rate, extinction behavior, and stability of gold, silver, and hybrid nanoparticles generated in different KCl concentrations. Extinction spectra, SEM images, SERS signal strength, and zeta potential were analyzed. Our results demonstrate that laser ablation in water and salt solutions yields nanoparticles with a spherical shape and a negative zeta potential. Importantly, we identified the optimal concentration of potassium chloride salt that maintains solution stability and SERS signal strength. Adsorbed chloride ions on silver nanoparticles were evidenced by low-frequency SERS band near 242 cm−1. A better understanding of the effect of KCl concentration on the properties of noble metal nanoparticles can lead to improved generation protocols and the development of tailored nanoparticle systems with enhanced stability and SERS activity.

Visualization and quantitative detection of foodborne Salmonella Typhimurium by functionalizing cysteamine (CS) stabilized gold nanoparticles (CS-AuNPs@phage)

Visualization and quantitative detection of foodborne Salmonella Typhimurium by functionalizing cysteamine (CS) stabilized gold nanoparticles (CS-AuNPs@phage)

Enhanced Stability of Gold Nanoparticles with Thioalkylated Carboxyl-Terminated Ligands for Applications in Biosensing

Enhanced Stability of Gold Nanoparticles with Thioalkylated Carboxyl-Terminated Ligands for Applications in Biosensing

One-step synthesis of stable gold nanoparticles using Aspergillus austwickii CO1 and its application in colorimetric detection of Mg2+ ion

One-step synthesis of stable gold nanoparticles using Aspergillus austwickii CO1 and its application in colorimetric detection of Mg2+ ion

Nanoformulation of dasatinib cannot overcome therapy resistance of pancreatic cancer cells with low LYN kinase expression

BackgroundPancreatic ductal adenocarcinoma (PDAC) is one of the most difficult to treat tumors. The Src (sarcoma) inhibitor dasatinib (DASA) has shown promising efficacy in preclinical studies of PDAC. However, clinical confirmation could not be achieved. Overall, our aim was to deliver arguments for the possible reinitiating clinical testing of this compound in a biomarker-stratifying therapy trial for PDAC patients. We tested if the nanofunctionalization of DASA can increase the drug efficacy and whether certain Src members can function as clinical predictive biomarkers.MethodsMethods include manufacturing of poly(vinyl alcohol) stabilized gold nanoparticles and their drug loading, dynamic light scattering, transmission electron microscopy, thermogravimetric analysis, Zeta potential measurement, sterile human cell culture, cell growth quantification, accessing and evaluating transcriptome and clinical data from molecular tumor dataset TCGA, as well as various statistical analyses.ResultsWe generated homo-dispersed nanofunctionalized DASA as an AuNP@PVA-DASA conjugate. The composite did not enhance the anti-growth effect of DASA on PDAC cell lines. The cell model with high LYN expression showed the strongest response to the therapy. We confirm deregulated Src kinetome activity as a prevalent feature of PDAC by revealing mRNA levels associated with higher malignancy grade of tumors. BLK (B lymphocyte kinase) expression predicts shorter overall survival of diabetic PDAC patients.ConclusionsNanofunctionalization of DASA needs further improvement to overcome the therapy resistance of PDAC. LYN mRNA is augmented in tumors with higher malignancy and can serve as a predictive biomarker for the therapy resistance of PDAC cells against DASA. Studying the biological roles of BLK might help to identify underlying molecular mechanisms associated with PDAC in diabetic patients.

Nanostructured systems based on pluronics to carry gold nanoparticles and methylene blue aiming for multimodal therapy

The rise of multidrug-resistant microorganisms has become a cause of concern in the biomedical field. In this sense, this study focuses on the development of an effective treatment for infectious diseases mediated by Multimodal Therapy, combining Photodynamic Therapy (PDT), and Photothermal Therapy (PTT). The system involves the synthesis and stabilization of gold nanoparticles (AuNPs) in Pluronic® micelles of F-127 and P-84, combined with the Methylene Blue (MB) aiming effects against microorganisms. It is noteworthy that the AuNPs were synthesized in situ in the copolymer using the solid dispersion technique. These copolymers were strategically chosen for evaluation purposes with our study involving P-123 previously published in this journal. Thus, the effect of the length of the PEO and PPO blocks can be delineated concerning the synthesis of AuNPs. In this case, copolymer F127 has PPO blocks identical to P-123 while P-84 has PEO blocks compatible with P-123. Characterization of the formulations included electronic absorption spectroscopy, dynamic light scattering, and transmission electron microscopy. Fluorescence quenching studies by Stern Volmer plots indicated the location of the MB in the hydrophilic corona of the micelles. In general, was verified that reducing the PEO/PPO ratio favors the formation of AuNPs, possibly due to the greater number of reducing sites per unit mass of the polymer. The formulations remained stable for at least 15 days, and photothermal studies showed a temperature increase of at least 11 °C. The photothermal effect proved reversible after three heating–cooling cycles, revealing a synergy between MB and AuNPs in heat generation, hindered by increased irradiance and rapid photobleaching of MB. The in vitro susceptibility tests with Candida albicans and Staphylococcus aureus demonstrated effective inhibition of the microorganisms. The result shows that AuNPs for itself do not affect the fungal/bacteria lineage. However, the MB/AuNPs combination samples, showed excellent fungal and bacterial inhibition at low drug concentrations.

Highly stable and efficient gold nanoparticles films facilitated by thiourea for catalytic reduction of nitrophenol in water

Water pollution from nitrophenol, a common nitrogen-containing aromatic pollutant, is becoming increasingly significant. Making the conversion of nitrophenol to the less toxic and more easily biodegradable aminophenol is a promising strategy to treat industrial wastewater. A simple and efficient method for treating nitrophenol was investigated using gold nanoparticles (AuNPs) with thiourea and fabricating AuNPs films via filtration for the first time. The prepared AuNPs film with nanoporous structure exhibits good structural stability and excellent catalytic activity. The results show that the optimal concentration of adding thiourea is 20 μg/mL, and the optimal concentration of adding NaBH4 is 1000 mM. After treatment with 20.0 μg/mL thiourea, the prepared AuNPs film catalyzes the degradation of 1.0 mM 2-nitrophenol to 2-aminophenol in just 150 sec. The AuNPs film provides a high density of active sites at the interface, and its stable nanoporous structure brings the substrate nitrophenol closer to the active center, thus enhancing the efficiency of catalytic reduction. Besides, the AuNPs films treated with thiourea still maintained good catalytic performance after seven cycles of catalysis and the catalytic efficiency is still as high as 90%. The thiourea-treated AuNPs film sets a precedent for the innovation of novel catalysts that is a very promising industrial strategy for reducing nitrophenol to aminophenol, offering significant economic advantages.