Gold Oxide Nanoparticles Research Articles

Highly selective detection of methamphetamine in urine using biosynthesized graphene oxide-gold nanoparticle composite modified electrodes

This study presents a novel electrochemical aptasensor for the detection of methamphetamine, utilizing a biosynthesized graphene oxide-gold nanoparticle (GO-AuNP) composite. The nanocomposite was synthesized using Shewanella oneidensis MR-1, offering a green and cost-effective alternative to traditional chemical methods. Characterization by UV–vis spectroscopy, TEM, XRD, and FTIR confirmed the successful formation of the GO-AuNP composite, with AuNPs averaging 18.3 ± 3.7 nm in diameter uniformly distributed on GO sheets. The aptasensor was optimized for aptamer concentration (10 μM), incubation time (30 minutes), and pH (7.4). Electrochemical impedance spectroscopy measurements revealed a linear relationship between the change in charge transfer resistance and the logarithm of methamphetamine concentration from 0.5 nM to 500 nM. The aptasensor achieved a detection limit of 0.15 nM, surpassing many existing methods. Cross-reactivity studies with potential interferents showed minimal response, with all tested compounds exhibiting less than 15 % relative signal compared to methamphetamine. The sensor demonstrated good reproducibility (RSD = 4.8 %) and retained over 90 % of its initial response after 30 days of storage. Analysis of spiked urine samples yielded recovery rates between 96.8 % and 103.5 %, validating the aptasensor's potential for real-world applications in sports doping control and clinical diagnostics.

A sandwich-type electrochemical sensor based on RGO-CeO2-Au nanoparticles and double aptamers for ultrasensitive detection of glypican-3.

Asandwich-type electrochemical aptasensor for ultrasensitive detection ofglypican-3 (GPC3)was constructed using GPC3 aptamer (GPC3Apt) labelled reduced graphene oxide-cerium oxide-gold nanoparticles (RGO-CeO2-Au NPs) as the signal probe and the same GPC3Apt as the capture probe. The electrochemical redox properties of CeO2 (Ce3+/Ce4+) in the RGO-CeO2-Au NPs indicate the electrochemical signals. When the target GPC3 was present, an "aptamer-protein-aptamer" sandwich structure was formed on the sensing interface due to the specific binding between the protein and aptamers, resulting in an increased electrochemical redox signal detected by differential pulse voltammetry (DPV) technique. Under optimal conditions, the established aptasensor exhibited a logarithmic linear relationship between the current response and GPC3 concentration in the range 0.001-100.0ng/mL, with a minimum detection limit of 0.74pg/mL. Using the spike-recovery tests for measurement of the human serum samples, the recovery was from 99.26 to 114.01%, and the RSD range was 3.04 to 5.34%. Furthermore, the sandwich-type electrochemical aptasensor exhibited excellent performance characteristics such as good stability, high specificity, and high sensitivity, demonstrating effective detection of GPC3 in human serum samples and can be used as a clinical detection tool for GPC3.

Chemiluminescence Immunoassay for Sensitive Detection of C-reactive Protein Using Graphene Oxide–Gold Nanoparticle–Luminol Hybrids as Enhanced Luminogenic Molecules

Chemiluminescence Immunoassay for Sensitive Detection of C-reactive Protein Using Graphene Oxide–Gold Nanoparticle–Luminol Hybrids as Enhanced Luminogenic Molecules

One-pot radiolytically synthesized reduced graphene oxide-gold nanoparticles composites and exploration in energy storage

Graphene and its composites are of primary importance, particularly in the field of energy storage. Numerous bottom-up and top-down methods have been proposed in the literature to produce these materials with enhanced physicochemical properties. Recently, an innovative and green methodology was developed based on ionizing radiation, allowing the quantitative synthesis of graphene oxide-based materials. With the aim to extend this strategy for the preparation of hybrid nanomaterials, the objective of this work was the one-pot synthesis of nanocomposites composed of reduced graphene oxide – gold nanoparticles (rGO-AuNPs) via gamma ray-induced radiolytic reduction. UV–Vis Absorption Spectroscopy, Fourier Transform Infrared Spectroscopy, Raman Spectroscopy and X-ray Photoemission Spectroscopy were utilized to comprehensively evaluate the reduction degree of graphene oxide and the formation of gold nanoparticles. Atomic Force Microscopy and Scanning Electron Microscopy were employed to obtain the morphological and topographical information on synthesized nanocomposites. Thermal properties were investigated by Thermogravimetric Analysis and electrical properties were investigated using Cyclic Voltammetry and Potentiostatic Charge and Discharge method. The results demonstrated the successful reduction of graphene oxide and gold ions through the drastic transformation of oxygen-containing functional groups and the formation of gold nanoparticles. Electrical characterization results highlighted the excellent electrical properties of radiosynthesized rGO-AuNPs composites and their great potential for supercapacitance application.

β-Cyclodextrin Functionalized Reduced Graphene Oxide–Gold Nanoparticles for Electrochemical Detection of Stigmasterol in Ganoderma boninense-Infected Oil Palm Leaves

β-Cyclodextrin Functionalized Reduced Graphene Oxide–Gold Nanoparticles for Electrochemical Detection of Stigmasterol in Ganoderma boninense-Infected Oil Palm Leaves

One-pot synthesized plasmonic black gold nanoparticles for efficient photocatalytic CO oxidation

The one-pot synthesis of plasmonic black gold will facilitate rapid exploration of black gold's applications in a range of fields and also pave the way for scalable industrial deployment.

Exploration of structure sensitivity of gold nanoparticles in low-temperature CO oxidation

A theoretical investigation of the dynamic structure–reactivity relation of Au nanoparticles in CO oxidation.

Insight into the Role of the Amino‐Organosilane Modifier in Improving the Catalytic Activity of ZnO‐Supported Gold Species in Base‐Free Oxidation of Benzyl Alcohol

AbstractUnderstanding the factors that affect the reactivity of gold nanoparticles (Au NPs) in the catalytic oxidation of organic compounds remains an important issue. Of particular significance is tuning the effect of metal‐support interaction toward improving the catalytic performance of Au NPs. The main goal of this study is to provide new insight into the role of the amino‐organosilane (APMS) modifier, used for anchoring of gold species on ZnO support, in controlling the reactivity of Au NPs in H2O2 activation and the subsequent catalytic oxidation of benzyl alcohol. This study reveals that APMS modifier weakens the electronic interaction between ZnO and Au NPs, leading to a lower catalase‐like activity toward H2O2 in comparison to that observed for modifier‐free gold catalyst of similar size of nanoparticles. As a result, a slower rate of oxygen evolution resulted in higher activity in the oxidation of benzyl alcohol and enabled more efficient utilization of H2O2 under base‐free conditions. No radical species were formed during the oxidation reaction, and molecular oxygen formed in situ in the reaction medium was the primary oxidant responsible for the catalytic conversion of benzyl alcohol.

Investigation of electrocatalytic activity of palladium nanoparticle for ammonia borane oxidation via single‐entity electrochemistry

AbstractAmmonia borane (AB) has garnered significant attention as a high‐efficiency energy source, prompting extensive investigations into its electrochemical oxidation. One prominent avenue of research focuses on the development of electrocatalysts to enhance the oxidation of AB. Employing the novel approach of single‐entity electrochemistry (SEE), the electrocatalytic properties of gold (Au), silver (Ag), and palladium (Pd) nanoparticles (NPs) for AB oxidation were explored. In the case of Au and Ag NPs, SEE experiments yielded no discernible current signal, in contrast to the electrocatalytic currents observed with bulk electrodes. However, when Pd NPs were utilized, characteristic staircase signals in the SEE measurements were observed. The variation of the SEE current signal for Pd NPs under different applied potentials, AB concentrations, and NP concentrations was further investigated. An analysis of the SEE signal elucidated the conditions under which Pd NPs can effectively catalyze AB oxidation at the single NP level.

A highly sensitive electrochemical sensor based on poly(3-aminobenzoic acid)/graphene oxide-gold nanoparticles modified screen printed carbon electrode for paraquat detection

Herein, a modified screen printed carbon electrode (SPCE) based on a composite material, graphene oxide-gold nanoparticles (GO-AuNPs), and poly(3-aminobenzoic acid)(P3ABA) for the detection of paraquat (PQ) is introduced. The modified electrode was fabricated by drop casting of the GO-AuNPs, followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA. The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy (SEM) for each step of modification. The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode. In addition, the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate, which stimulate redox reaction on the modified electrode, thus improving the sensitivity of PQ analysis. The SPCE/GO-AuNPs/P3ABA offered a wide linear range of PQ determination (10−9–10−4 mol/L) and low limit of detection (LOD) of 0.45 × 10−9 mol/L or 0.116 µg/L, which is far below international safety regulations. The modified electrode showed minimum interference effect with percent recovery ranging from 96.5% to 116.1% after addition of other herbicides, pesticides, metal ions, and additives. The stability of the SPCE/GO-AuNPs/P3ABA was evaluated, and the results indicated negligible changes in the detection signal over 9 weeks. Moreover, this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.

Polyacrylonitrile/cellulose nanofiber supported gold nanoparticles for liquid-phase aerobic oxidation of benzyl alcohol to benzaldehyde

Polyacrylonitrile/cellulose nanofiber supported gold nanoparticles for liquid-phase aerobic oxidation of benzyl alcohol to benzaldehyde

Bioactive superparamagnetic iron oxide-gold nanoparticles regulated by a dynamic magnetic field induce neuronal Ca2+ influx and differentiation

Treating neurodegenerative diseases, e.g., Alzheimer's Disease, remains a significant challenge due to the limited neuroregeneration rate in the brain. The objective of this study is to evaluate the hypothesis that external magnetic field (MF) stimulation of nerve growth factor functionalized superparamagnetic iron oxide-gold (NGF-SPIO-Au) nanoparticles (NPs) can induce Ca2+ influx, membrane depolarization, and enhance neuron differentiation with dynamic MF (DMF) outperforming static MF (SMF) regulation. We showed the that total intracellular Ca2+ influx of PC-12cells was improved by 300% and 535% by the stimulation of DMF (1 Hz, 0.5 T, 30min) with NGF-SPIO-Au NPs compared to DMF alone and SMF with NGF-SPIO-Au NPs, respectively, which was attributed to successive membrane depolarization. Cellular uptake performed with the application of sodium azide proved that DMF enhanced cellular uptake of NGF-SPIO-Au NPs via endocytosis. In addition, DMF upregulated both the neural differentiation marker (β3-tubulin) and the cell adhesive molecule (integrin-β1) with the existence of NGF-SPIO-Au NPs, while SMF did not show these effects. The results imply that noninvasive DMF-stimulated NPs can regulate intracellular Ca2+ influx and enhance neuron differentiation and neuroregeneration rate.

A Novel Large-Diameter Optical Fiber Glucose Biosensor Based on Glucose Oxidase– Graphene Oxide–Gold Nanoparticles

A novel glucose large-diameter optical fiber LSPR sensor was constructed based on chemical cross-linking and electrostatic methods of glucose oxidase-graphene oxide-gold nanoparticles (GOD-GO-AuNPs). The GOD-catalyzed oxidation of glucose reacts with oxygen to produce gluconic acid and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , leading to a change in its ambient refractive index, which in turn leads to a significant shift in the LSPR peak of GO-AuNPs on the fiber. The structure and morphology of GOD-GO-AuNPs were studied by FTIR, UV-vis spectroscopy, SEM, and TEM, respectively. GO improves the stability of the composite particles, reduces the biotoxicity of the metal particles, and the immobilization of glucose oxidase on the surface of the composite particles improved the enzyme activity. A fiber-optic sensor was prepared based on the optimal conditions, and the sensitivity of the sensor was 11.134 nm/(mg/mL) in the range of 0 to 1.0 mL with a response time of 55 s. It showed good anti-interference, selectivity and can be used for real detection. This method combines the advantages of GO, AuNPs, and large diameter fiber-optical which show promise for simple, stable, and cost-effective applications in the field of glucose detection.

Biomass-assisted fabrication of rGO-AuNPs as surface-enhanced Raman scattering substrates for in-situ monitoring methylene blue degradation

Reduced graphene oxide-gold nanoparticles nanocomposites (rGO-AuNPs) with high surface-enhanced Raman scattering (SERS) activity was created by biomass-assisted green synthesis with Lilium casa blanca petals biomass for the first time, and its application for methylene blue (MB) degradation was explored through in-situ monitoring. Lilium casa blanca petals biomass was used as a reducing agent to reduce GO and chloroauric acid successively when carrying out rGO-AuNPs in-situ synthesis while it also acted as a capping agent. The produced rGO had oxygen-containing functional groups which had an outstanding performance in enhancing the SERS effect. Characterization results confirmed that the AuNPs were grafted onto the rGO sheet, and the mechanism study showed that total flavonoids in Lilium casa blanca petals biomass were the main biological compounds involved in the reduction. rGO-AuNPs had a high Raman enhancement factor (EF) which could reach 3.88 × 107. The synthesized nanocomposite also had a good catalytic activity that could be employed as catalyst in MB degradation, and it could complete degradation within 15min. The reaction rate increased linearly with the amount of rGO-AuNPs, and the degradation could be in-situ monitored both by UV and SERS.

Functionalized Hybrid Iron Oxide–Gold Nanoparticles Targeting Membrane Hsp70 Radiosensitize Triple-Negative Breast Cancer Cells by ROS-Mediated Apoptosis

Triple-negative breast cancer (TNBC) a highly aggressive tumor entity with an unfavorable prognosis, is treated by multimodal therapies, including ionizing radiation (IR). Radiation-resistant tumor cells, as well as induced normal tissue toxicity, contribute to the poor clinical outcome of the disease. In this study, we investigated the potential of novel hybrid iron oxide (Fe3O4)-gold (Au) nanoparticles (FeAuNPs) functionalized with the heat shock protein 70 (Hsp70) tumor-penetrating peptide (TPP) and coupled via a PEG4 linker (TPP-PEG4-FeAuNPs) to improve tumor targeting and uptake of NPs and to break radioresistance in TNBC cell lines 4T1 and MDA-MB-231. Hsp70 is overexpressed in the cytosol and abundantly presented on the cell membrane (mHsp70) of highly aggressive tumor cells, including TNBCs, but not on corresponding normal cells, thus providing a tumor-specific target. The Fe3O4 core of the NPs can serve as a contrast agent enabling magnetic resonance imaging (MRI) of the tumor, and the nanogold shell radiosensitizes tumor cells by the release of secondary electrons (Auger electrons) upon X-ray irradiation. We demonstrated that the accumulation of TPP-PEG4-FeAuNPs into mHsp70-positive TNBC cells was superior to that of non-conjugated FeAuNPs and FeAuNPs functionalized with a non-specific, scrambled peptide (NGL). After a 24 h co-incubation period of 4T1 and MDA-MB-231 cells with TPP-PEG4-FeAuNPs, but not with control hybrid NPs, ionizing irradiation (IR) causes a cell cycle arrest at G2/M and induces DNA double-strand breaks, thus triggering apoptotic cell death. Since the radiosensitizing effect was completely abolished in the presence of the ROS inhibitor N-acetyl-L-cysteine (NAC), we assume that the TPP-PEG4-FeAuNP-induced apoptosis is mediated via an increased production of ROS.

Electrochemical platform based on activated carbon/graphene oxide-gold nanoparticle composites for the electrochemical sensing of methylparaben in cosmetic samples

We report on a simple and highly sensitive square wave voltammetric method for the determination of methylparaben (MP) using a pencil graphite electrode (PGE) modified with gold nanoparticles and activated carbon/graphene oxide (denoted as AuNP@AC/PGE and AuNP@GO/PGE). The modified electrodes display enhanced electroactivity and antifouling for the oxidation of MP compared to the unmodified PGE. Under optimized conditions, both types of the modified electrode exhibit similar efficiency in terms of the linear response to MP in the concentration range between 0.030 and 1.0 mM, high reproducibility (RSD of 3.44–3.51%), and repeatability (RSD of 2.79–3.36%). However, the AuNP@GO/PGE (2.02 μM) provided a better limit of detection than the AuNP@AC/PGE (2.17 μM). In addition, the modified electrodes also have a remarkably stable response, and up to 30–40 analyses are possible at 0.2 mM of MP. Additionally, the sensors provided acceptable recoveries ranging from 85 to 110% for the samples spiked with MP from four types of cosmetics. In addition, the results agreed with those obtained from conventional high performance liquid chromatography coupled with diode array detection.

Development of conducting cellulose paper for electrochemical sensing of procalcitonin

An electrochemical paper-based sensor was developed for the detection of bacterial infection (BI)-specific biomarker procalcitonin (PCT). Reduced graphene oxide-gold nanoparticles (rGO-AuNP) and poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) were synthesized and were fabricated to a disposable, portable, and inexpensive cellulose fiber paper (CFP) substrate. rGO-AuNP-PEDOT:PSS nanocomposite-modified conductive paper-based biosensing platform was efficaciously fabricated by a constant and simple coating procedure. rGO-AuNP-PEDOT:PSS nanocomposite-modified conductive paper electrode was found to provide a sensitive and conductive substrate for PCT detection. The presence of rGO-AuNP-PEDOT:PSS nanocomposite on CFP substate was investigated by Fourier transform infrared spectrometry, field emission scanning electron microscopy, ultraviolet-visible spectroscopy, and X-ray diffraction studies. The electrochemical behavior of rGO-AuNP-PEDOT:PSS @CFP surface was studied with impedance spectroscopy, cyclic voltammetry, and chronoamperometry techniques. This low-cost paper-based biosensor has a linear range for PCT of 1 × 103 to 6 × 107fgmL-1. This developed sensor exhibited good reproducibility with a relative standard deviation (RSD) of about 3.7%. The proposed CFP-based biosensor has been proven as an accelerated simple point-of-care (POC) exploratory approach for early PCT diagnosis in inadequate areas with limited production facilities, computational techniques, and highly skilled experts.

A multiplexed electrochemical quantitative polymerase chain reaction platform for single-base mutation analysis

Detection of single-based mutation (SbM), which is of ultra-low abundance against wild-type alleles, are typically constrained by the level of multiplexing, sensitivity for single-base resolution and quantification accuracy. In this work, an electrochemical quantitative polymerase chain reaction (E-PCR) platform was developed for multiplexed and quantitative SbM analysis in limited and precious samples with single-nucleotide discrimination. A locked nucleic acid (LNA)-mediated multiplexed PCR system in a single, closed tube setup was firstly constructed to selectively amplify the SbM genes while suppressing the wild-type alleles. The amplicons were detected simultaneously through hybridization with the sequence-specific hairpin probes anchored on a reduced graphene oxide-gold nanoparticles functionalized electrode surface. With the inclusion of an LNA-mediated PCR step upstream of the electrochemical detection, we improved the limit of detection (LOD) by 2 orders of magnitude, down to an ultralow-level of 5 copies μL−1. The platform achieved an ultra-sensitive and specific detection with 0.05% against a background of 10, 000 copies of wild-type alleles. It is highly adaptive and has the potential to enable expanded multiplexed detection in parallel, thus providing a universal tool for multiplexed SbM identification.

A portable and sensitive dopamine sensor based on AuNPs functionalized ZnO-rGO nanocomposites modified screen-printed electrode

Dopamine (DA) is an important neurotransmitter and one of the biomarkers of psychiatric diseases such as Parkinson's disease and schizophrenia. Therefore, it is urgent to explore an effective method to realize rapid and sensitive detection of DA. In this paper, porous zinc oxide microspheres-functional reduced graphene oxide composites (ZnO-rGO) were successfully prepared by a simple solution method, then gold nanoparticles (AuNPs) were combined by electrodeposition. Zinc oxide porous microspheres-reduced graphene oxide-gold nanoparticles nanocomposites were used to modify the screen-printed electrode ([email protected]) to fabricate a fast and efficient non-enzymatic electrochemical sensing platform for detecting DA in biological samples. The sensor obtained a good linear range of 0.5 μM to 100 μM and a low detection limit of 0.294 μM at S/N = 3. Additionally, a sensor was applied to the determination of DA in human biological samples, and it showed good stability and reproducibility, making it an excellent candidate material in the field of biosensors.

Highly Specific Loop-Mediated Isothermal Amplification Using Graphene Oxide-Gold Nanoparticles Nanocomposite for Foot-and-Mouth Disease Virus Detection.

Loop-mediated isothermal amplification (LAMP) is a molecular diagnosis technology with the advantages of rapid results, isothermal reaction conditions, and high sensitivity. However, this diagnostic system often produces false positive results due to a high rate of non-specific reactions caused by formation of hairpin structures, self-dimers, and mismatched hybridization. The non-specific signals can be due to primers used in the methods because the utilization of multiple LAMP primers increases the possibility of self-annealing of primers or mismatches between primers and templates. In this study, we report a nanomaterial-assisted LAMP method that uses a graphene oxide–gold nanoparticles (AuNPs@GO) nanocomposite to enable the detection of foot-and-mouth disease virus (FMDV) with high sensitivity and specificity. Foot-and-mouth disease (FMD) is a highly contagious and deadly disease in cloven-hoofed animals; hence, a rapid, sensitive, and specific detection method is necessary. The proposed approach exhibited high sensitivity and successful reduction of non-specific signals compared to the traditionally established LAMP assays. Additionally, a mechanism study revealed that these results arose from the adsorption of single-stranded DNA on AuNPs@GO nanocomposite. Thus, AuNPs@GO nanocomposite is demonstrated to be a promising additive in the LAMP system to achieve highly sensitive and specific detection of diverse diseases, including FMD.