Au NPs Research Articles

Photoelectrochemical sensor consisting of sulfhydryl-borate ester modified A1/B1 type Pillar[5]arene-functionalized gold NPs

Recognition of mitochondrial reactive oxygen species (ROS) in cells is essential for understanding the critical roles of different ROS in biology reaction processes. In this study, an ultrasensitive and specific photoelectrochemical (PEC) sensor is constructed and applied for the capture and identification of H2O2 in cells. For the targeted detection of H2O2 in cells containing similar groups, such as •OH and O2•-, a new sulfhydryl-borate ester modified A1/B1 type pillar[5]arene (BP5) with a specific borate group is designed as a specific recognition molecule, and Au nanoparticles (Au NPs) are synthesized as the photoactive material. Specifically, the localized surface plasmon resonance (LSPR) of the Au NPs and host-guest interaction between BP5 and H2O2 increase the photocurrent signal. At the same time, specific groups on BP5 react with H2O2 to specifically recognize it. The Au@BP5/GCE shows strong photoelectrochemical response for the detection of H2O2 with limit of detection (0.33 pM, S/N=3), an extended linear range (1–60 pM), high specificity, good stability and excellent reproducibility.

Phytotoxicity, cytogenotoxicity and antimicrobial potential of extracts with gold-silver bimetallic nanoparticles obtained from pteridophyte spores

Investigating the toxicity of naturally occurring or synthesized nanoparticles for various applications is absolutely necessary for environmental protection and safety use. The aim of these research was to investigated the phytotoxicity, cytogenotoxicity and antibacterial potential of the extracts with gold-silver bimetallic nanoparticles (Au-Ag NPs) obtained from green synthesis in Asplenium scolopendrium L. and Dryopteris filix-mas (L.) Schott spores extracts. To our knowledge, this is the first report of the Au-Ag NPs phytosynthesis based on extracts obtained from fern spores. UV-Vis spectroscopy analysis of the samples revealed the maximum absorbance, characteristic of samples with bimetallic nanoparticles, which varied depending on the Au:Ag ratio. Energy-dispersive X-ray spectroscopy confirmed the presence and distribution of Au, Ag and other chemical elements. The presence of specific secondary metabolites in the extracts that helped in NPs biosynthesis stimulated growth processes. Good results were recorded for some Dryopteris filix-mas samples, correlated with a significantly increased mitotic index. Cell viability decreased significantly in three of the nanoformulations. Only extracts with Au-Ag NPs showed antimicrobial effect against Staphylococcus aureus ATCC 25923, Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 8739. The testing of the antibacterial potential of these extracts must be extended to other bacterial strains and other microorganisms, the search of new antimicrobial resources being an urgent necessity nowadays.

Nanoparticle Uptake and Bioaccumulation in Pisum sativum L. (Green Pea) Analyzed via Dark-Field Microscopy, Infrared Spectroscopy, and Principal Component Analysis Combined with Machine Learning

The green pea (Pisum sativum L.) is an economically, nutritionally, and culturally important legume. It is a crop that is subject to various investigations due to its popularity with the development of various protocols in different topics, except for nano-biotechnological studies. This work was carried out to evaluate the uptake, distribution, translocation, and bioaccumulation of the single-walled carbon nanotubes (CNTs) and gold nanoparticles (AuNPs) within the economically important plant Pisum sativum morphologically and anatomically with a dark-field microscopy system. Data were analyzed for morphological parameters such as stem, tendril, root length, number, shape, width-length of the stipules, and root-stem-stipule. Our results proved the stimulation for growth and anatomical parameters such as CNTs aggregates and AuNPs particles at paranchyma, cortex, spongia cells, starch formation and accumulation in lenticels, stoma cells, and stomatal pores. In this study, we compared the utilization of the entire available Attenuated Total Reflectance—Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectral range (525–4000 cm−1) for conducting principal component analysis (PCA) without excluding any specific spectral wavenumbers with the spectral range chosen based on larger PCA loadings. The results demonstrate that for both chosen spectral ranges of the PCA score plots, utilizing only the first three principal components (PCs), we effectively visually separated three groups: (1) plants treated with Au NPs, (2) plants treated with CNTs, and (3) control plants without nanoparticle treatment using ATR-FTIR spectral data from combined samples of root, stem, and leaves from the Pisum sativum plant. Our investigation shows that green pea, a species of the Fabaceae family, is low-cost, fast, and non-toxic and requires an environmentally safe process in the area of nanotechnology in bio-application regarding the green synthesis of nanoparticles; it is a step for green mining, phytoremediation, delivering drugs, and biomolecules. Our findings show that green pea and the Fabaceae family have more advantages for the biological synthesis of C-Au nanoparticles and guide soil health, agricultural development, pharmaceuticals, drug delivery science, and other types of medicinal investigations with a new approach, while a lot of economic plants in the Fabaceae family will be available for the green synthesis of more NPs with single and rapid protocols and will be a popular family in nano-biotechnological studies in the next few decades.

Understanding electron structure of covalent triazine framework embraced with gold nanoparticles for nitrogen reduction to ammonia

Regulating the electron structure and precise loading sites of metal-active sites within the highly conjugated and porous covalent-triazine frameworks (CTFs) is essential to promoting the nitrogen reduction reaction (NRR) performance for electrocatalytic ammonia (NH3) synthesis under ambient conditions. Herein, experimental method and density functional theory (DFT) calculations were conducted to deeply probe the effect on NRR of the modulation of modulating the electron structure and the loading site of gold nanoparticles (Au NPs) in a two-dimensional (2D) CTF. 2D CTF synthesized using melem and hexaketocyclohexane octahydrate as building blocks (denoted as M−HCO−CTF) served as a robust scaffold for loading Au NPs to form an M−HCO−CTF@AuNP hybrid. DFT results uncovered that well-defined Au sites with tunable local structure were the active site for driving the NRR, which can significantly suppress the conversion of H+ into *H adsorption and enhance the nitrogen (N2) adsorption/activation. The overlapped Au (3d) and *N2 (2p) orbitals lowered the free energy of the rate-determining step to form *NNH, thereby accelerating the NRR. The M−HCO−CTF@AuNPs electrocatalyst exhibited a large NH3 yield rate of 66.3 μg h−1 mg−1cat. and a high Faraday efficiency of 31.4 % at − 0.2 V versus reversible hydrogen electrode in 0.1 M HCl, superior to most reported CTF-based ones. This work can provide deep insights into the modulation of the electron structure of metal atoms within a porous organic framework for artificial NH3 synthesis through NRR.

Au-decorated Ti3C2Tx/porous carbon immunoplatform for ECM1 breast cancer biomarker detection with machine learning computation for predictive accuracy

Electrochemical immunosensors, surpassing conventional diagnostics, exhibit significant potential for cancer biomarker detection. However, achieving a delicate balance between signal sensitivity and operational stability, especially at the heterostructure interface, is crucial for practical immunosensors. Herein, porous carbon (PC) integration with Ti3C2Tx-MXene (MX) and gold nanoparticles (Au NPs) constructs a versatile immunosensing platform for detecting extracellular matrix protein-1 (ECM1), a breast cancer-associated biomarker. The inclusion of PC provided robust structural support, enhancing electrolytic diffusion with an expansive surface area while synergistically facilitating charge transfer with Ti3C2Tx. The biosensor optimized with 1.0 mg PC demonstrates a robust electrochemical redox response to the surface-bound thionine (th) redox probe, utilizing an inhibition-based strategy for ECM1 detection. The robust antibody-antigen interactions across the PC-integrated Ti3C2Tx-Au NPs platform (MX-Au-C-1) enabled robust ECM1 detection within 0.1–7.5 nM, with a low limit of detection (LOD) of 0.012 nM. The constructed biosensor shows improved operational stability with a 98.6 % current retention over 1 h, surpassing MXene-integrated (MX-Au) and pristine Au NPs (63.2 % and 44.3 %, respectively) electrodes. Moreover, the successful adaptation of the artificial neural network (ANN) model for predictive analysis of the generated DPV data further validates the accuracy of the biosensor, promising its future application in AI-powered remote health monitoring.

Novel dynamic light scattering immunosensor for prostate specific antigens based upon dual-tyramine signal amplification strategy

The sensitive detection of biomarkers is crucial for the early diagnosis, treatment, and improvement of the quality of life of patients. A novel dynamic light scattering-dual tyramine signal amplification strategy (DLS-dTSA) was constructed to detect prostate-specific antigen (PSA). The Oligo 1 was first immobilized in a 96-well plate for PSA capture. Afterwards, horseradish peroxidase (HRP) and Oligo 2 functionalized AuNPs (HRP-Au NPs-Oligo 2) bound to Oligo 1 through DNA hybridization. In the presence of hydrogen peroxide (H2O2), tyramine could be converted into a transient radical intermediate by HRP, leading to the aggregation of tyramine and HRP-labeled AuNPs (tyramine-AuNPs-HRP) near HRP-AuNPs-Oligo 2, triggering the first TSA process. Later, the PSA was added into the 96-well plate, to specifically recognize aptamer and thus depart the Au-aggregate from the 96-well plate. Then H2O2 was added to the Au-aggregate solution, triggering the free Au-aggregate to gather again, realizing the second TSA amplification. The average diameter of Au NPs increased linearly with the concentration of PSA during the range of 0.0001 – 1000 ng mL−1, and the limit of detection was 0.033 pg mL−1. Moreover, this strategy has been used to analyze PSA in human serum samples successfully, demonstrating the potential application of the proposed method for rapid clinical and early clinical diagnosis of prostate cancer in vitro.

Green decorated of gold nanoparticles over kaolin mediated by plant extract and investigation of its anti-bile duct cancer properties in the in vitro condition

In the current research, kaolin-decorated Au nanoparticles were produced by a green medication method by using Strawberry root’s extract as a natural coating and reducing component for capping and stabilizing Au NPs over the kaolin. The Au NPs/kaolin material was thoroughly characterized using XRD, FE-SEM, EDX-elemental mapping, TEM, and ICP. Characterization data confirmed the well-supporting of Au NPs over the kaolin. TEM images displayed the spherical shaped gold nanoparticles averaging 20–40 nm in size over the kaolin surface. The cytotoxicity and anti-bile duct cancer properties of Au NPs/kaolin were investigated through the utilization of MTT assay on three bile duct cancer cell lines, namely OCUCHLM1, EGI1, and GBCSD. Au nanoparticles (Au NPs) combined with kaolin exhibited dose-dependent anti-bile duct cancer properties and significantly reduced cell viability in OCUCHLM1, EGI1, and GBCSD cell lines. Importantly, these effects were observed without causing any cytotoxicity in the normal cell line (HUVECs). The OCUCHLM1 cell line exhibited the most significant anti-bile duct cancer effects when treated with Au NPs/kaolin, surpassing the results observed in other cell lines. Upon the successful validation of the aforementioned findings in the clinical trial investigations, Au NPs/kaolin could potentially serve as an effective chemotherapeutic agent in combating bile duct cancer.

AuNPs/DNAzyme/siRNA three-dimensional nanomotor for CEACAM6 RNA detection in cerebrospinal fluid and gene therapy of NSCLC

Non-small-cell lung cancer (NSCLC), with the most challenging problem of leptomeningeal metastasis (LM), is the most prevalent malignancy worldwide. Our previous research found that carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) serve as a potential biomarker in NSCLC-LM. Which is also a therapeutic target for NSCLC and related to cell migration, invasion, and metastasis. Herein, we first constructed a diagnostic and treatment-integrated Au NPs/DNAzyme/siRNA nanoplatform to detect the CEACAM6 RNA in cerebrospinal fluid and living cells, and inhibit tumor growth by gene therapy. The nanoprobe would be triggered by CEACAM6 RNA and the fluorescence signal would be amplified by DNAzyme cyclic reaction for in-situ imaging. The sensitivity and specificity of Au nanoprobe for the detection of CSF samples were 83.33% and 91.67%, respectively. The delivery of siRNA by Au NPs can enhance its uptake and accumulation by tumor cells, leading to a down-regulation of the CEACAM6 protein and ultimately inhibiting the invasion and migration of tumor cells. Furthermore, this nanoprobe have been effectively implemented for in-situ fluorescence imaging and tumor growth inhibition in mice models. It is undoubted that such a combination nanoplatform would be a promising diagnosis and treatment-integrated strategy for potential biomarker detection and cancer therapy.

A ratiometric SERS aptasensor based on catalytic hairpin self-assembly mediated cyclic signal amplification strategy for the reliable determination of E. coli O157:H7.

Aratiometric SERS aptasensor based on catalytic hairpin self-assembly (CHA) mediated cyclic signal amplification strategy was developed for the rapid and reliable determination of Escherichia coli O157:H7. The recognition probe was synthesized by modifying magnetic beads with blocked aptamers, and the SERS probe was constructed by functionalizing gold nanoparticles (Au NPs) with hairpin structured DNA and 4-mercaptobenzonitrile (4-MBN). The recognition probe captured E. coli O157:H7 specifically and released the blocker DNA, which activated the CHA reaction on the SERS probe and turned on the SERS signal of 6-carboxyl-x-rhodamine (ROX). Meanwhile, 4-MBN was used as an internal reference to calibrate the matrix interference. Thus, sensitive and reliable determination and quantification of E. coli O157:H7 was established using the ratio of the SERS signal intensities of ROX to 4-MBN. This aptasensor enableddetection of 2.44 × 102 CFU/mL of E. coli O157:H7 in approximately 3h without pre-culture and DNA extraction. In addition, good reliability and excellent reproducibility were observed for the determination of E. coli O157:H7 in spiked water and milk samples. This study offered a new solution for the design of rapid, sensitive, and reliable SERS aptasensors.

State of the art on plasma-liquid route synthesis monometallic Au, bimetallic Au/Ag core–shell and alloy nanoparticles: Toxicological, сanalytical, antimicrobial activity for environmental control

Nanoparticles (Au monometallic, bimetallic structures Au-Ag alloy and Aucore – Agshell) were synthesized in aqueous solutions with traditional capping agent - sodium citrate, using a one-step (for monometalic and alloy structure) and two–step (for Aucore – Agshell NPs) liquid-phase anode type plasma process. The effects of parameters of synthesis: precursors concentration, the solution plasma process discharge time, molar contents Ag+/Au3+ for alloy NPs, and molar content of Ag+ for Au core NP to the characteristics of the synthesized NPs, including average size (the size distribution, polydispersity index), optical absorption properties ect.) were investigated. The synthesized nanoparticles have the following characteristics: Au NPs with λ=530–540 nm and d = 5–60 nm, the monometalic structure; Ag/Au with the λ=410–530 nm and d = 28–80 nm, bimatalic strucrure of alloy; NPs with significant blue-shift the λ=530→410 nm, depending the shell thickness (the thickness of the deposited Ag shells varied from ∼1–15 nm) and d = 21–35 nm for NPs core(Au)–shell(Ag). TEM images clearly confirm the effectiveness of a one- and two-step plasma-liquid treatment for the synthesis of monometallic Au NPs and the two different structures of the NPs (bimetallic structures Au-Ag alloy and Aucore@– Agshell). The effect of nanoparticle structure on antimicrobial and catalytic properties relative to their respective monometallic counterparts was demonstrated. Among the different investigated structure NPs only for bimetallic core−shell structured AucoreAgshell NPs was found strong synergistic effect for antimicrobial and catalytical activity.

Sustainable synthesis of Au nanoparticles templated over chitosan/pectin hydrogel for the treatment of gastric cancer

This report demonstrates the sustainable synthesis of hybrid biopolymer hydrogel supported Au NPs followed by its characterizations and biological explorations. The chitosan/pectin (CS-Pec) composite hydrogel was used as the support. The biopolymers might function as an eco-friendly reductant for the Au3+ ions over and above encapsulating stabilizer of the Au NPs by exploiting their electron rich organo-functions. UV–Vis, SEM, TEM, EDX, elemental mapping and XRD techniques were engaged to appraise the physicochemical features of the material. Subsequently, the material (Au NPs@CS-Pec) was subjected to diverse biological applications and following the course it showed high antioxidant activities against DPPH free radical. The related IC50 of the antioxidant material against DPPH found as 139 µg/mL. Towards the oncological investigation, it was used against the gastric cancer cell lines (AGS and KATO III) and the corresponding IC50 values were 225.3 and 341.5 µg/mL respectively. The outcome justifies that the produced NPs have successfully inhibited the proliferation of gastric cancer cells, and those are mostly eliminated at a high dose of the NPs.

One-pot electrochemical detection of foodborne pathogen based on in situ nucleic acid amplification and wash-free assay.

Asignal amplification electrochemical biosensor chip was developed to integrate loop-mediated isothermal amplification (LAMP) based on in situ nucleic acid amplification and methyl blue (MB) serving as the hybridization redox indicator for sensitive and selective foodborne pathogen detection without a washing step. The electrochemical biosensor chip was designed by a screen-printed carbon electrode modified with gold nanoparticles (Au NPs) and covered with polydimethylsiloxane membrane to form a microcell. The primers of the target were immobilized on the Au NPs by covalent attachment for in situ amplification. The electroactive MB was used as the electrochemical signal reporter and embedded into the double-stranded DNA (dsDNA) amplicons generated by LAMP. Differential pulse voltammetry was introduced to survey the dsDNA hybridization with MB, which differentiates the specifically electrode-unbound and -bound labels without a washing step. Pyrene as the back-filling agent can further improve response signaling by reducing non-specific adsorption. This method is operationally simple, specific, and effective. The biosensor showed a detection linear range of 102-107CFUmL-1 with the limit of detection of 17.7CFUmL-1 within 40min. This method showed promise for on-site testing of foodborne pathogens and could be integrated into an all-in-one device.

The mechanism of gold nanoparticle-enhanced corrosion acceleration of polylactide (PLA)-coated biodegradable iron and zinc

The commercial application of biodegradable metals (BMs), such as iron (Fe) and zinc (Zn), is hampered by their slow degradation rate. Polylactide (PLA) coatings on BMs have been proven to accelerate the corrosion of Fe and Zn but with limited success. This is the first study exploring the use of gold nanoparticles (Au NPs) to enhance and control the corrosion of polylactide (PLA)-coated Fe and Zn. The Au NPs enhanced the corrosion rate of Fe and Zn by promoting micro-galvanic corrosion after nanoparticle agglomeration. The optimal corrosion acceleration depended on the polymer's molecular weight, coating thickness, and coating structure. The results suggest that the Au-reinforced PLA-based coatings can be used to control Fe and Zn corrosion rates in the physiological environment.

A sensitive gold nanoflower-based lateral flow assay coupled with gold staining technique for the detection of SARS-CoV-2 antigen.

Anenhanced lateral flow assay (LFA) is presentedfor rapid and highly sensitive detection of acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigens with gold nanoflowers (Au NFs) as signaling markers and gold enhancement to amplify the signal intensities. First, the effect of the morphology of gold nanomaterials on the sensitivity of LFA detection was investigated. The results showed that Au NFs prepared by the seed growth method showed a 5-fold higher detection sensitivity than gold nanoparticles (Au NPs) of the same particle size, which may benefit from the higher extinction coefficient and larger specific surface area of Au NFs. Under the optimized experimental conditions, the Au NFs-based LFA exhibited a detection limit (LOD) of 25 pg mL-1 for N protein using 135nm Au NFs as the signaling probes. Thesignal was further amplified by using a gold enhancement strategy, and the LOD for the detection of N protein achieved was5 pg mL-1. The established LFA also exhibited good repeatability and stability and showed applicability in the diagnosis of SARS-CoV-2 infection.

Mxene-based capacitive enzyme-free biofuel cell Self-Powered sensor for lead ion detection in human plasma

In response to the health risks posed by heavy metal lead, we have developed a self-powered sensor specifically designed for detection of lead ions in this work. This sensor is designed based on an enzyme-free biofuel cell as a self-powered source. The biofuel cell utilizes two-dimensional lamellar Au NPs-Ti3C2Tx heterostructures as the capacitive anode substrate material. The Ti3C2Tx MXene with the excellent charge storage capacity and fast discharge characteristics, provides a large instantaneous current for signal amplification. Furthermore, the DNA walker technique was combined to regulate the loading of ultra-small Au NPs exhibiting glucose oxidase-like properties. Meanwhile, Co, Mn nitrogen-doped carbon-based nanosheets were designed as the cathode with outstanding oxygen reduction reaction catalytic activity. As a result, the constructed enzyme-free biofuel cell has been used to detect Pb2+ with a wide linear range (0.01–7500 nM) and a low detection limit (0.43 pM). It has been successfully applied to the determination of Pb2+ in human plasma, achieving excellent recovery rates (94.0–110.5 %). The developed capacitive anodes not only significantly optimized the performance of the biofuel cell self-powered sensors, but also provided important insights for the future design and construction of biofuel cells.

Rapid intracellular pH measurement based on electroporation- surface-enhanced Raman scattering

In this study, electroporation-surface-enhanced Raman scattering (SERS) was applied to rapidly measure intracellular pH. The generation of a sensitive SERS probe for measuring pH in the range of 6.0–8.0 was accomplished through the conjugation of the pH-sensitive molecule 4-mercaptobenzoic acid (4-MBA) to the surface of gold nanoparticles (Au NPs) through its thiol functional group. This bioprobe was then rapidly introduced into nasopharyngeal carcinoma CNE-1 cells by electroporation, followed by SERS scanning and the fitting of intensity ratios of each detection point’s Raman peaks at 1423 cm−1 and 1072 cm−1, to create the pH distribution map of CNE-1 cells. The electroporation-SERS assay introduces pH bioprobes into a living cell in a very short time and disperses the nanoprobe throughout the cytoplasm, ultimately enabling rapid and comprehensive pH analysis of the entire cell. Our work demonstrates the potential of electroporation-SERS for the biochemical analysis of live cells.

Simultaneously determining dopamine, acetaminophen and chlorpromazine with high performance on coordinated functional acupuncture needle electrode

Developing fast and sensitive methods to simultaneously analyze neurotransmitter and drug is of scientific significance for diagnosing and treating neurological diseases. Acupuncture can adjust and balance the blood gas, yin and yang and other physiological states through inserting acupuncture needle into the patient’s body, so as to treat diseases, care health and strengthen body. In this study, the stainless-steel needle was used as electrode matrix for the sensor. Gold nanoparticles (Au NPs), polydopamine (PDA) and multi-wall carbon nanotubes (MWCNTs) were layer-by-layer modified onto the bare acupuncture needle (AN) through green and environment-friendly method, and the new interface showed efficient performance for simultaneous monitoring dopamine (DA), acetaminophen (AC) and chlorpromazine (CPZ). It was interesting that the synergistic interface of MWCNTs, PDA and AuNPs exhibits effect conductivity, and high electrocatalytic activity for three molecules. The sensor optimally exhibits wide linear ranges of 0.08–100 and 100–1000 μM for DA, 0.07–100 and 100–1000 μM for AC, 0.1–100 and 100–450 μM for CPZ, respectively. The low detection limits are 0.015, 0.012, and 0.022 µM correspondingly, which are competitively compared to previous reports. In addition, the sensor exhibits good anti-interference ability in the presence of excessive interference. The sensor can successfully monitor DA, AC and CPZ in human serum and urine with the recovery rates from 97.2 % to 102.6 %. The sensor showed good repeatability, stability, and reproducibility. The simultaneous detection of needlelike sensor should play important roles in biomedicine.

Chronoamperometric Ammonium Ion Detection in Water via Conductive Polymers and Gold Nanoparticles.

Monitoring of ammonium ion levels in water is essential due to its significant impact on environmental and human health. This work aims to fabricate and characterize sensitive, real-time, low-cost, and portable amperometric sensors for low NH4+ concentrations in water. Two strategies were conducted by cyclic voltammetry (CV): electrodeposition of Au nanoparticles on a commercial polyaniline/C electrode (Au/PANI/C), and CV of electropolymerized polyaniline on a commercial carbon electrode (Au/PANIep/C). Au NPs increase the electrical conductivity of PANI and its ability to transfer charges during electrochemical reactions. The electrode performances were tested in a concentration range from 0.35 µM to 7 µM in NH4+ solution. The results show that the Au/PANI/C electrode performs well for high NH4+ concentrations (0.34 µM LoD) and worsens for low NH4+ concentrations (0.01 µM LoD). A reverse performance occurs for the electrode Au/PANIep/C, with a 0.03 µM LoD at low NH4+ concentration and 0.07 µM LoD at high NH4+ concentration. The electrodes exhibit a good reproducibility, with a maximum RSD of 3.68% for Au/PANI/C and 5.94% for Au/PANIep/C. In addition, the results of the repeatability tests show that the electrochemical reaction of sensing is fully reversible, leaving the electrode ready for a new detection event.

A facile green synthesis of gold nanoparticles using Canthium parviflorum extract sustainable and energy efficient photocatalytic degradation of organic pollutants for environmental remediation

Organic dye and nitrophenol pollution from textiles and other industries present a substantial risk to people and aquatic life. One of the most essential remediation techniques is photocatalysis, which uses the strength of visible light to decolorize water. The present study reports Canthium Parviflorum (CNP) leaf extract utilization as an effective bio-reductant for green synthesis of Au NPs. A simple, eco-friendly process with low reaction time and temperature was adopted to synthesize CNP extract-mediated Au-NPs (CNP-AuNPs). The prepared AuNPs characterization involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS) surface area analysis, ultraviolet–visible spectroscopy (UV–Vis). XRD results showed that the cubic-structured AuNPs had a crystallite size of 14.12 nm. Assessment of organic dyes performance in degrading brilliant green (BTG) and amido black 10B (AMB) under visible light irradiation highlights an impressive 83.25% and 86% degradation efficiency within 120 min, accompanied by a kinetic rate constant dyes was found to be 0.0828 min⁻1, BTG, and 0.0123 min⁻1, Furthermore, the reduction of 4-nitrophenol by NaBH4 using CNP-AuNPs as a catalyst demonstrated good catalytic performance and rapid degradation at 89.4%. and rate constant 0.099 min−1 followed pseudo-first-order. The LC-MS analysis identified various intermediates during the degradation of the CR dye. Radical trapping experiments suggest that photogenerated free electrons and hydroxyl radicals are crucial for degrading the amido black 10B dye The AuNPs influenced the significant factors responsible for the photocatalytic activity, such as the increase in range of absorbance, increased e− and h+ pair separation, improvement in the charge transfer process, and active site formation, which significantly enhanced the process of degradation. We found that the CNP-AuNPs could effectively remove dyes and nitrophenol from industrial wastewater.

Enhanced Optical Limiting of Gold Nanoparticles/Porous Carbon Nanocomposites.

With the wide application of laser weapons, the requirements of laser protection technology are becoming more and more strict. Therefore, it is important to find ideal optical limiting (OL) materials to protect human eyes and detectors. In this work, the nonlinear optical responses of gold nanoparticles/porous carbon (Au NPs/PC) nanocomposites prepared by the reduction method were studied using the nanosecond Z-scan technique. Compared with porous carbon, the Au NPs/PC nanocomposites show a lower damage threshold, a bigger optical limiting index and a wider absorption spectrum. The interaction between gold nanoparticles and porous carbon enhances the nonlinear scattering effect of suspended bubbles. These results indicate that Au NPs composites have potential applications in the protection of human eyes and detectors.