AuNPs Nanocomposites Research Articles

Supported of gold nanoparticles on carboxymethyl lignin modified magnetic nanoparticles as an efficient catalyst for reduction of nitroarenes and treatment of human melanoma

This article represents the synthesis and characterizations of Au NPs immobilized and carboxymethyl lignin (CML) modified Fe3O4 nanoparticles (Fe3O4@CML/Au NPs) following a bio-inspired protocol without the participation of any toxic and harmful reductant or stabilizers. Following various physicochemical methodologies, such as FT-IR, FE-SEM, TEM, EDX, XRD, VSM, and ICP-OES, the textural characteristics and different structural aspects were evaluated. The Fe3O4@CML/Au NPs nanocomposite was subsequently explored towards the catalytic reduction of diverse aromatic nitro functions using green conditions. An excellent yield were achieved within very short reaction time. Nine recycling runs of the nanocatalyst were completed without a discernible loss of catalytic activity, thanks to its easy magnetic recovery. The DPPH assay was carried out to examine the antioxidant effectiveness. The Fe3O4@CML/Au NPs nanocomposite inhibited half of the DPPH in a 250 μg/mL solution. To measure the anti-human melanoma efficacy of Fe3O4@CML/Au NPs nanocomposite, MTT assay was applied on HT144, MUM2C, IPC-298 and SKMEL24 cell lines. Fe3O4@CML/Au NPs nanocomposite had high anti-human melanoma efficacy on above tumor cells. The best finding of anti-human melanoma properties of Fe3O4@CML/Au NPs nanocomposite was seen in the case of the SKMEL24 cell line. The IC50 of Fe3O4@CML/Au NPs nanocomposite was 137, 145, 185, and 125 μg/mL against HT144, MUM2C, IPC-298 and SKMEL24 cells, respectively. This research exhibited remarkable anti-human melanoma and antioxidant efficacies of Fe3O4@CML/Au NPs nanocomposite in the in vitro condition.

Gold and nanosized titanium carbide MXene heterozygotes as highly efficient visible-light responsive photocatalysts for ammonia synthesis

Utilizing sunlight to drive photocatalytic conversion of N2 into NH3 is a promising approach to mitigate the substantial energy consumption associated with the Haber–Bosch process. However, significant challenges remain unaddressed before the practical application of photocatalysts can be realized. Various materials and nanoscale design strategies have been investigated with the aim of achieving a high quantum yield. Among these, MXenes can be a promising photocatalyst for NH3 synthesis due to its excellent N2 fixation performance. In this work, we investigate the use of nanosized Ti3C2 MXene and plasmonic gold nanoparticles (AuNPs) for NH3 synthesis with visible light. We observed a formation of heterozygote structures between AuNPs and reduced nanosized Ti3C2, resulting in a 4.4-fold increase in the photocatalytic activity compared to that of reported microscale Ti3C2 with AuNPs nanocomposites. The improved photocatalytic performance is originated from the enhanced light absorption of AuNPs, and the efficient N2 fixation by the nanosized Ti3C2 MXene with a reduced chemical state, which is demonstrated experimentally with gas chromatographic analysis. The various experimental conditions involving catalysts, concentration, pH, and scavengers are investigated, the highest photocatalytic performance was achieved with the heterozygote structures of AuNPs and nanosized Ti3C2 MXene under optimized conditions, and yielding 5334 μmol gcat−1 h−1 of ammonia, an amount at least 13-fold higher than that of previously developed photocatalysts.

A fluorescent aptasensor for quantification of cocaine mediated by signal amplification characteristics of UiO-66/AuNPs nanocomposite

Due to the detrimental effects of cocaine on the human body such as organ damage, paranoia, immunodeficiency, cardiovascular disease, blood pressure, and stress, it is highly required to develop sensing approaches for its rapid and facile determination. Based on the signal enhancement capability of the UiO-66/AuNPs nanocomposite and acting as a capture agent, we designed a cost-effective fluorescent aptasensor for cocaine detection. The cocaine presence in the sample would cause a considerable escalation in the quenching of the fluorescence signal. The aptasensor achieved the linear response range over 0.5 μM–20 μM with a low detection limit of 0.178 μM. The selectivity of the designed aptasensing assay was successfully confirmed by examining several analgesic drugs. The aptasensor was employed for cocaine determination in human serum as the real samples. This method has a substantial benefit the for development of a low-cost and facile tool in medicine and forensic science.

Enhanced cytotoxic effect of doxorubicin conjugated gold nanoparticles on breast cancer model

BackgroundThe difficulty of achieving targeted drug delivery following administration of presently marketed anticancer therapeutics is still a concern. Metallic nanoparticles (NPs) appear to be promising in this regard. The present study focused on the use of gold nanoparticles (AuNPs) as a drug carrier for anticancer Doxorubicin (DOX) forming DOX–AuNPs nanocomposite. The anticancer effect of the prepared nanocomposite was evaluated using SRP essay on breast cancer cell line (MCF7) for different incubation times (24 h,48, and72hr). The prepared DOX–AuNPs nanocomposite was investigated by UV–visible spectroscopy, TEM, fluorescence spectroscopy, and FTIR spectroscopy.ResultsOur results showed that the prepared AuNPs and DOX–AuNPs nanocomposite have spherical and small size10 ± 2 nm and 12 ± 2 nm respectively. The potential cytotoxicity of the DOX-AuNPs nanocomposite on the MCF7 cell line was significantly increased compared to free DOX. The 20 µM DOX- AuNPs nanocomposite produced a similar decrease in cell survival as 80 µM free DOX.ConclusionFuture work is in progress to investigate the positive effects of the prepared nanocomposite for chemo-photothermal combination treatment.

A novel conductive nanocomposite-based biosensor for ultrasensitive detection of microRNA-21 in serum, using methylene blue as mediator

MicroRNA-21 (miRNA-21) is a common biomarker with high expression in breast tumors. Therefore, sensitive detection of miRNA-21 is of great significance for clinical breast tumor diagnosis. A TH/rGO/CMK-3/AuNPs nanocomposite is composed of thionine (TH), reduced graphene oxide (rGO), ordered mesoporous carbon (CMK-3), and gold nanoparticles (AuNPs), which help to increase the specific surface area of a glassy carbon electrode (GCE) and to amplify the DPV signal. Meanwhile, methylene blue (MB) was combined with the capture probe guanine and absorbed by the composite material to mediate the differential pulse voltammetry (DPV) of the obtained miRNA biosensor. The current response decreased with increasing miRNA-21 concentration under optimal conditions. The biosensor responds to miRNA-21 in the 0.1fM-1 pM concentration range, and the detection limit (LOD) was 0.046 fM. Moreover, human serum samples were effectively detected utilizing the miRNA-21 biosensor with satisfactory results.

Formulation of a novel anti-human oral squamous cell carcinoma supplement by gold nanoparticles-Kaolin nanocomposite

In this work, we have described the biogenic synthesized gold nanoparticles being supported over Kaolin mediated by Pomegranate peel extract as natural reducing and stabilizing agent under mild conditions without any toxic reagents. Pomegranate peel extract was used as a green reducing agent and an excellent stabilizer of the synthesized Au NPs. Physicochemical characterization of the as-synthesized Kaolin@extract/Au NPs nanocomposite was carried out through electron microscopy (SEM and TEM), energy dispersive X-ray spectroscopy (EDX), elemental mapping, X-ray diffraction (XRD) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). In the cellular and molecular part of the recent study, the treated cells with Au NPs-Kaolin nanocomposite were assessed by MTT assay for 48 h about the cytotoxicity and anti-human oral squamous cell carcinoma properties on normal (HUVEC) and oral squamous cell carcinoma cell lines i.e. HSC-2, HSC-3, HSC-4 and Ca9-22. It has been observed that the Au NPs with spherical shape and size were dispersed homogeneously on the modified-Kaolin surface. The significance of this study is the novel initiative to combine the gold nanoparticle with inexpensive Kaolin clay and utilization of them as anticancer agent. The IC50 of Kaolin@extract/Au nanocomposite were 277, 367, 250 and 545 µg/mL against HSC-2, HSC-3, HSC-4 and Ca9–22 cell lines, respectively. The viability of malignant human oral cell lines reduced dose-dependently in the presence of Kaolin@extract/Au NPs nanocomposite.

Carbon dots and gold nanoparticles doped metal-organic frameworks as high-efficiency ECL emitters for monitoring of cell apoptosis

Synthesis of highly efficient, cost-effective, Easy labeling electrochemiluminescence (ECL) luminescent materials is attractive in developing highly sensitive ECL sensors for many applications such as clinical diagnostics, biosecurity, and environmental monitoring. Herein, by doping carbon dots (CDots) and gold nanoparticles (AuNPs) into zeolitic imidazolate framework (ZIF-8), novel high-efficiency ECL emitters CDots@ZIF-8/AuNPs nanocomposites were prepared. Our experiment indicated that ZIF-8 in the nanocomposites not only act as carrier for ECL labels, but as an ECL accelerator to convert the CDots to CDots•–, causing the enhanced ECL intensity of CDots in K2S2O8 solution. AuNPs, which have excellent conductivity, were formed in the pores of ZIF-8 to further enhance the ECL signals. As a result, the nanocomposites showed a final about 7-fold ECL intensity as compared to the pure CDots. AuNPs in the nanocomposites could also provide a platform for effective attaching the biomolecular, making the nanocomposites ideally suited for building biosensor. As a proof of concept, the prepared CDots@ZIF-8/AuNPs was successfully applied in the rapid and simple ECL monitoring of caspase-3 activity during cell apoptosis, which gives impetus to the design of new ECL luminescent materials with ultimate applications in highly sensitive bioanalysis.

Preparation of GO/Fe3O4@PMDA/AuNPs nanocomposite for simultaneous determination of As3+ and Cu2+ by stripping voltammetry

One of the critical challenges in the simultaneous determination of As3+ and Cu2+ by stripping voltammetry is the overlapping of their oxidation peaks. Therefore, the engineering of nanostructured sensors in order to uplift their electrochemical performance is a significant issue for the codetection of As3+ and Cu2+. Herein, we modified a glassy carbon electrode with a new nanocomposite based on poly methyldopa along with gold nanoparticles immobilized on the surface of magnetic graphene oxide (GCE/GO/Fe3O4@PMDA/AuNPs) that can determine As3+ and Cu2+ with great sensitivity. Optimization of the measurement conditions by square wave stripping voltammetry (SWSV) caused the oxidation peaks of As3+ and Cu2+ to be distinguished significantly from each other, while the peak currents of As3+ and Cu2+ increased 9–12 fold, respectively, compared to the bare electrode. The proposed electrode exhibits low detection limits (S/N ≥ 3): 0.15 ppb for As3+ and 0.11 ppb for Cu2+. The GCE/GO/Fe3O4@PMDA/AuNPs also has good linearity over a wide concentration range from 5 to 500 ppb for As3+ and 0.5–750 ppb for Cu2+. The good recovery values were obtained for the analysis of As3+ and Cu2+ in pool and drinking water samples.

A colorimetric sensor for DNA detection: Combination of synergistic coupling catalysis and significant distinction in the dimensional structure of DNA

Herein, the simple and highly sensitive colorimetric sensor for DNA detection was constructed using the close correlation between DNA dimension and peroxidase activity of graphene oxide (GO)/AuNPs nanocomposite. One-dimensional and linear ss-DNA was hybridized into double helix DNA of three-dimensional space conformation, resulting in that catalytic activity of GO/AuNPs for the oxidation of enzyme substrate TMB significantly enhanced. Thus, DNA dimension transformation caused by hybridization is converted into color rendering events of TMB oxidation. The results show that the dimensional transformation of DNA can efficiently regulate the peroxidase activity of GO/AuNPs. Together with the effective amplifying for the color reaction of TMB by GO/AuNPs’ synergistic coupling catalysis at the nanometer interface, the colorimetric sensor is highly sensitive to DNA detection. The detection limit is calculated to be 8.8 × 10−12 M, which is about 1 ~ 2 orders of magnitude lower than that of other nanozyme colorimetric analysis. Besides, this analysis only requires one-step hybridization reaction, and the whole analysis is carried out in the homogeneous system of liquid phase, which is extremely easy to operate and conducive to the automatic sensing design. The detected results for serum samples declare that this sensor has great potential in the application of real life systems.

Ultrasensitive electrochemiluminescence biosensor for the detection of tumor exosomes based on peptide recognition and luminol-AuNPs@g-C3N4 nanoprobe signal amplification

Highly sensitive determination of tumor exosomes is significant for early diagnosis of cancers and precision therapy. Herein, a sandwich peptide-based electrochemiluminescence (ECL) biosensor was developed for determination of phosphatidylserine (PS)-positive exosomes, a promising biomarker for early diagnosis of ovarian malignancy. A PS-specific binding peptide with high affinity was immobilized on Au nanoflowers (AuNFs) modified biosensing interface for recognition and capture of exosomes. Meanwhile, g-C3N4 nanosheet loaded with luminol capped AuNPs (Lum-AuNPs@g-C3N4) nanocomposite was used as the ECL signal nanoprobe. The g-C3N4 nanosheets with large surface area were not only utilized as the carrier to immobilize more peptides for recognition of exosomes but also used to catalyze co-reactant H2O2 decomposition to achieve the ECL signal amplification of luminol-H2O2 system. Under optimal conditions, the biosensor showed superior performances compared with most currently available methods, including wider linear range across 5 orders of magnitude and a lower detection limit (LOD) down to 39 particles μL−1. Moreover, the biosensor could be applicable for determination of exosomes in complex biological samples. This study indicates the combination of peptide recognition with nanoprobe as a label for signal amplification in sandwich ECL biosensing is a great promising strategy for sensitive and cost-effective determination of exosomes.

Water-soluble stable polymer nanocomposites with AuNPs based on the functional poly(1-vinyl-1,2,4-triazole-co-N-vinylpyrrolidone)

New water-soluble polymer nanocomposites with gold nanoparticles (AuNPs) were synthesized using functional copolymer of 1-vinyl-1,2,4-triazole with N-vinylpyrrolidone (poly(VT-co-VP)) as a stabilizing matrix. The polymer AuNPs nanocomposites were studied by transmission electron microscopy, scanning electron microscopy, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, atomic absorption and thermogravimetric analysis. The gold content in nanocomposites ranged from 4.4 to 25.7%wt (the gold content depends on the ratio of poly(VT-co-VP):Au (III)). The obtained polymer nanocomposites consist of isolated gold nanoparticles with a diameter of 1–12 nm having a predominately spherical shape, which are uniformly distributed throughout the bulk of the polymer matrix. Nanocomposites contain AuNPs of various sizes, which is determined by the ability of the polymer matrix to stabilize the different metal contents. The resulting AuNPs nanocomposites are promising materials for the design of novel hydrophilic antiseptics and antimicrobial components for medical purposes.

Strategy to improve gold nanoparticles loading efficiency on defect-free high silica ZSM-5 zeolite for the reduction of nitrophenols

Catalytic reduction of toxic and aqueous stable nitrophenols by gold nanoparticles (Au NPs) is hot issue due to the serious environmental pollution in recent years. But the expensive price and poor recycling performance of Au NPs limit its further application. Defect-free high silica zeolite is suitable support for Au NPs due to its cheaper price, higher stability and stronger adsorbability, but the low alumina content and defect sites usually lead to poor Au NPs loading efficiency. Herein, we reported the improved Au NPs loading efficiency on defect-free high silica ZSM-5 zeolite through the additional surface fluffy structure. The fluffy structure was created through the addition of multi-walled carbon nanotubes (MWCNTs) and ethanol into synthesis gel. Highly dispersed ca. 4 nm Au NPs on zeolite surface are prepared by the green enhanced sol-gel immobilization method. The Au NPs loading efficiency on conventional ZSM-5 zeolite is 10.7%, in contrast, this result can arrive to 82.6% on fluffy structure ZSM-5 zeolite. The fluffy structure ZSM-5 zeolite and Au NPs nanocomposites show higher efficiency than traditional Au/ZSM-5 nanocomposites towards catalytic reduction of nitrophenols. Additionally, the experiments with different affecting factors (MWCNTs dosage, aging time, catalysts dosage, pH, initial 4-NP concentration, storage time and recycling times) were carried out to test general applicability of the nanocomposites. And the degradation of nitrophenols experiment was operated to explore the catalytic performance of the prepared nanocomposites in further environmental application. The detailed possible relationship between zeolite with fluffy structure and Au NPs is also proposed in the paper.

Molecularly Imprinted Voltammetric Sensor Based on Chitosan-CNTs Decorated with AuNPs Nanocomposite for Catechol Detection

This research is based on the development of a novel, biocompatible and sensitive electrochemical imprinted sensor based on the detection of a phenolic compound, such as catechol, employing electroactive nanomaterials with the objective of improving the electron transfer between the electrode surface and the solution [1] and a natural biopolymer due to its excellent layer forming ability [2]. The development of the sensor is based on the modification of multiwalled carbon nanotubes (MWCNTs) with gold nanoparticles (AuNPs). The decorated MWCNTs have been recovered with a polymeric chitosan (CS) matrix generating a nanocomposite that contains the electroactive material inside. The polymeric matrix of CS that holds the modified MWCNTs has been electrodeposited in the presence of the phenolic compound on a boron doped diamond (BDD) electrode. The sensor surface has been structurally characterized to demonstrate the correct adsorption of the film and the correct recovery of the decorated carbon nanotubes on the BDD electrode surface. The performance as an electrochemical MIP sensor analyzed by cyclic voltammetry has offered excellent characteristics, demonstrating a high affinity to catechol with high selectivity, reproducibility, repeatability and sensitivity in the range of catechol concentrations from 0 to 1 mM. Finally, the implementation of the sensor to measure in a complex red wine sample has been carried out. The obtained results have resulted to be successful to quantify catechol in the real matrix. For these reasons, the proposed research manifests a promising and interesting way to implement an imprinting biocompatible polymers method in the development of an electrochemical sensor for phenols detection in the 4.0 industry.[1] S. A. Zaidi, Sensors Actuators B. Chem., 2018, 265,488-497.[2] A. Gopalan, S. Komathi, N. Muthuchamy, K. Lee, M. J. Whitcombe, L. Dhana, y G. Sai-anand, Prog. Polym. Sci., 2019 88, 1-129. Acknowledgments: Financial support by MINECO and FEDER (RTI2018-097990-B-100 and BES-2016-077825) and the Junta de Castilla y León-FEDER (VA-275P18) is gratefully acknowledged.

Highly sensitive and simple colorimetric assay of hydrogen peroxide and glucose in human serum via the smart synergistic catalytic mechanism.

Due to the own defects of natural enzymes, artificial simulated enzymes are always concerned. Here, the fabricated graphene oxide (GO)/AuNPs nanocomposite exhibits strong synergistic catalysis of peroxidase-mimicking enzymes in combination with the novel property of GO catalytic interface and AuNPs-mediated electron transfer. It can efficiently catalyze the oxidation of enzyme substrate TMB by hydrogen peroxide to form blue TMB oxide. Based on this, the rapid and highly sensitive colorimetric detection of hydrogen peroxide was achieved. Because of the wonderfully synergistic coupling catalysis from GO/AuNPs nanocomposites, the developed artificial enzyme has ultra-strong catalytic activity. For the detection of hydrogen peroxide, the detection limit of this colorimetric analysis is as low as 4.2×10-8M, which is about 1-2 orders of magnitude lower than that of the assays using other single nanoparticles as nanozymes. And it shows high sensitivity. The catalytic oxidation of the prepared nanocomposites to TMB can be completed in minutes, and the response is extremely fast. Combined with the reaction of glucose and glucose oxidase, the colorimetric analysis also realizes the rapid and highly sensitive detection of glucose in human serum. The research results infer that the smart synergy is an effective way to improve the catalytic activity of mimic enzyme. Together with its simplicity in preparation, the GO/AuNPs nanocomposite has excellent development potential in biomedical detection and biosensor design.

The role of gold nanoparticles in the structural and electrical properties of Cs/PVP blend

Pure gold nanoparticles (AuNPs) were prepared using a laser ablation technique. Nanocomposite films of chitosan (Cs) and polyvinyl pyrrolidone PVP blend embedded different concentrations of pure gold nanoparticles were prepared by the casting method. The structural, morphological, thermal and electrical properties of Cs/PVP–AuNPs nanocomposite were characterized and investigated before and after adding gold nanoparticles. The X-ray diffraction revealed the degree of crystallinity of Cs/PVP blend was decreased after the addition of gold nanoparticles. The intensity of some IR bands was changed due to the chemical interaction between the blend and AuNPs. Transmission electron microscope images of the samples which contain the gold nanoparticles show the spherical particles of nanogold with a size range nearly 5–30 nm. The thermogravimetric (TG) analysis shows an enhancement of the thermal stability of the films after the addition of AuNPs. The activation energy was calculated from the TG curves using Coats–Redfern and Broido methods. The AC electrical properties were studied from 100 Hz to 5 MHz with different temperatures. The values for dielectric constant (e′) and dielectric loss (e″) were decreased with an increase in both frequency and temperature.

Label-free microfluidic paper-based electrochemical aptasensor for ultrasensitive and simultaneous multiplexed detection of cancer biomarkers

Simultaneous detection of multiple tumor biomarkers in body fluids could facilitate early diagnosis of lung cancer, so as to provide scientific reference for clinical treatment. This paper depicted a multi-parameter paper-based electrochemical aptasensor for simultaneous detection of carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) in a clinical sample with high sensitivity and specificity. The paper-based device was fabricated through wax printing and screen-printing, which enabled functions of sample filtration and sample auto injection. Amino functional graphene (NG)-Thionin (THI)- gold nanoparticles (AuNPs) and Prussian blue (PB)- poly (3,4- ethylenedioxythiophene) (PEDOT)- AuNPs nanocomposites were synthesized respectively. They were used to modify the working electrodes not only for promoting the electron transfer rate, but also for immobilization of the CEA and NSE aptamers. A label-free electrochemical method was adopted, enabling a rapid simple point-of-care testing. Experimental results showed that the proposed multi-parameter aptasensor exhibited good linearity in ranges of 0.01–500 ng mL−1 for CEA (R2 = 0.989) and 0.05–500 ng mL−1 for NSE (R2 = 0.944), respectively. The limit of detection (LOD) was 2 pg mL−1 for CEA and 10 pg mL−1 for NSE. In addition, the device was evaluated using clinical serum samples and received a good correlation with large electrochemical luminescence (ECL) equipment, which would offer a new platform for early cancer diagnostics, especially in those resource-limit areas.

Comparison of electrocatalytic activity for glucose electrooxidation of gold nanoparticles fabricated by different methods

In this study, the gold nanoparticles (AuNPs) without carbon support were prepared using the well-known citrate reduction method. The carbon supported AuNPs nanocomposites were fabricated by two different approaches: chemical adsorption of AuNPs from the prepared citrate stabilized AuNP colloidal solution on the carbon powder surface and one-pot microwave-assisted synthesis. The nanocomposites were characterized using scanning electron microscopy (SEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES). The electrocatalytic activity of the prepared catalysts was evaluated for the electrooxidation of glucose in an alkaline media using cyclic voltammetry. The highest electrocatalytic activity was observed for the catalyst of carbon supported Au nanoparticles prepared by microwave-assisted synthesis, followed by the catalyst of carbon supported Au nanoparticles prepared by means of the adsorption method, whereas the pure Au nanoparticles without carbon support exhibited the lowest electrocatalytic properties for glucose electrooxidation.

FeS2−AuNPs Nanocomposite as Mimicking Enzyme for Constructing Signal‐off Sandwich‐type Electrochemical Immunosensor Based on Electroactive Nickel Hexacyanoferrate as Matrix

AbstractIn this work, a novel sandwich‐type electrochemical immunosensor with electroactive nickel hexacyanoferrate nanoparticles (NiHCFNPs) as matrix was constructed for α‐fetoprotein (AFP) detection in a signal‐off manner by using FeS2−AuNPs nanocomposite catalyzed insoluble precipitation to significantly inhibit the electrochemical signal. Initially, the NiHCFNPs with excellent electrochemical property was modified on the electrodeposited nano‐Au electrode to obtain a strong initial electrochemical signal. Subsequently, another nano‐Au layer was formed for immobilization of capture antibody (Ab1). In the presence of target AFP, the prepared FeS2−AuNPs‐Ab2 bioconjugate could be specifically recognized and immobilized on electrode through the sandwich‐type immunoreaction. The FeS2 with large specific surface areas were used as scaffolds to load abundant mimicking enzyme AuNPs. With the help of hydrogen peroxide (H2O2), FeS2−AuNPs with peroxidase‐like activity accelerated the 4‐chloro‐1‐naphthol (4‐CN) oxidation with generation of insoluble precipitation on electrode, which would greatly hinder the electron transfer and thus caused the decrease of electrochemical signal for quantitative determination of AFP. This approach achieved a wide dynamic linear range from 0.0001 to 100 ng mL−1 with an ultralow limit detection of 0.028 pg mL−1. Especially, the proposed AFP immunosensor can be applied to detect human serum samples with satisfactory results, indicating a potential application in clinical monitoring of tumor biomarkers.

Sensitive and fast analysis of terbutaline sulfate in food using a modified electrode based on a MoS2/AuNPs nanocomposite

An electrochemical non-enzymatic sensor for terbutaline sulfate (TBS) has been constructed from a nanocomposite of MoS2 and AuNPs modified on a glassy carbon electrode, and this was successfully applied to the quantitative analysis of trace TBS in food samples.

Bifunctional aptasensor based on novel two-dimensional nanocomposite of MoS2 quantum dots and g-C3N4 nanosheets decorated with chitosan-stabilized Au nanoparticles for selectively detecting prostate specific antigen

A novel nanostructured biosensing platform was designed based on two-dimensional (2D) nanocomposite of graphitic carbon nitride (g-C3N4) nanosheets and MoS2 quantum dots (MoS2 QDs), followed by decoration with chitosan-stabilized Au nanoparticles (CS-AuNPs) (denoted as MoS2QDs@g-C3N4@CS-AuNPs), of which CS-AuNPs were prepared by plasma enhanced-chemical vapor deposition. Owning to the good surface plasmon performance of the CS-AuNPs and excellent electrochemical activity of MoS2QDs@g-C3N4 nanosheets, the as-obtained 2D MoS2QDs@g-C3N4@CS-AuNPs nanocomposite was simultaneously explored to construct both surface plasmon resonance spectroscopy (SPR) sensor and electrochemical aptasensor. The MoS2QDs@g-C3N4@CS-AuNPs-based aptasensor shows strong bio-binding affinity toward the prostate specific antigen (PSA) targeted aptamer strands as compared to the individual component, including MoS2 QDs, g-C3N4, and CS-AuNPs. When detecting PSA, the low limit of detection (LOD) of 0.71 pg mL−1 deduced by electrochemical aptasensor is three orders of magnitude lower than that deduced by SPR sensor (0.77 ng mL−1). As expected, both SPR sensor and electrochemical aptasensor demonstrate good selectivity, highly stability, acceptable reproducibility, and well consistent applicability in human serum. The satisfactory results suggest potential application of the MoS2QDs@g-C3N4@CS-AuNPs in bifunctional biosensing fields and clinical monitoring of cancer markers.