Novel voltammetric tumor necrosis factor-alpha (TNF-α) immunosensor based on gold nanoparticles involved in thiol-functionalized multi-walled carbon nanotubes and bimetallic Ni/Cu-MOFs

TNF-α, as a pro-inflammatory cytokine, regulates some physiological and pathological courses. TNF-α level increases in some important diseases such as cancer, arthritis, and diabetes. In addition, it displays an important function in Alzheimer’s and cardiovascular diseases. Herein, a novel, sensitive, and selective voltammetric TNF-α immunosensor was prepared by using gold nanoparticles involved in thiol-functionalized multi-walled carbon nanotubes (AuNPs/S-MWCNTs) as sensor platform and bimetallic Ni/Cu-MOFs as sensor amplification. Firstly, the sensor platform was developed on glassy carbon electrode (GCE) surface by using mixture of thiol-functionalized MWCNTs (S-MWCNTs) and AuNPs. Then, capture TNF-α antibodies were conjugated to sensor platform by amino-gold affinity. After capture TNF-α antibodies’ immobilization, a new-type voltammetric TNF-α immunosensor was developed by immune reaction between AuNPs/S-MWCNTs immobilized with primer TNF-α antibodies and bimetallic Ni/Cu-MOFs conjugated with seconder TNF-α antibodies. The prepared TNF-α immunosensor was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). A linearity range of 0.01–1.0 pg mL−1 and a low detection limit of 2.00 fg mL−1 were also obtained for analytical applications. Graphical abstract: [Figure not available: see fulltext.] © 2021, Springer-Verlag GmbH Germany, part of Springer Nature

A novel QCM immunosensor development based on gold nanoparticles functionalized sulfur-doped graphene quantum dot and h-ZnS-CdS NC for Interleukin-6 detection

Interleukin 6 (IL-6) acts as both a proinflammatory and anti-inflammatory cytokine and is generally utilized as an important diagnostic biomarker for sepsis. In addition, the high levels of IL-6 measured in plasma have been associated with pathological inflammation. A novel quartz crystal microbalance (QCM) immunoassay method was presented for high sensitivity and selectivity detection of interleukin-6 (IL-6) based on gold nanoparticles functionalized sulfur-doped graphene quantum dot (AuNPs/S-GQD) and hollow ZnS–CdS nanocage (h-ZnS-CdS NC). Firstly, AuNPs/S-GQD nanocomposite was synthesized in the presence of tetrachloroauric acid and then conjugated onto anti-IL-6 antibodies by amino-gold affinity. The sandwich-type QCM immunoassay probe was prepared by immune-reaction between AuNPs/S-GQD/QCM immobilized with anti-IL-6 capture antibodies and h-ZnS-CdS NC including detection anti-IL-6 antibodies in the presence of target IL-6. The prepared QCM immunoassay probe was characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The QCM immunosensor showed a linearity range (0.01–2.0 pg mL−1) and a low detection limit (3.33 fg mL−1). Lastly, high stable and selective QCM immunosensor was applied to prepared plasma samples with good recovery. © 2021 Elsevier B.V

Carbohydrate antigen 19-9 electrochemical immunosensor based on 1D-MoS2 nanorods/LiNb3O8 and polyoxometalate-incorporated gold nanoparticles

The diagnosis of disease and the monitoring of patient in cancer research are related to biomarkers. Carbohydrate antigen 19-9 (CA 19-9) as the main tumor biomarker is necessary for digestive tract associated cancers. In this study, 1D-MoS2 nanorods/LiNb3O8 (1D-MoS2 NRs/LNO) as signal amplification and polyoxometalate-incorporated gold nanoparticles (AuNPs@POM) as sensor platform were prepared and the electrochemical immunosensor application was conducted based on 1D-MoS2 NRs/LNO and AuNPs@POM for CA 19-9 detection. After the preparation of AuNPs@POM nanocomposite, primer antibody immobilization was conducted via amino-gold affinity between primer antibody and AuNPs@POM nanocomposite. After that, strong pi-pi and electrostatic interactions between seconder antibody and 1D-MoS2 NRs/LNO provided the successful conjugation of seconder antibody. The physicochemical characterizations including scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD) were performed for electrochemical CA 19-9 immunosensor. Furhermore, to asses the electrochemical performance of the immunosensor, cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectrospcopy (EIS) techniques were performed. The quantification limit (LOQ) and the detection limit (LOD) values were obtained as 0.10 mu U mL(-1) and 0.030 mu U mL(-1), respectively. This immunosensor having high selectivity, stability and reusability creates a novel chance for clinical immunoassays

Electrochemical immunosensor development based on core-shell high-crystalline graphitic carbon nitride@carbon dots and Cd0.5Zn0.5S/d-Ti3C2Tx MXene composite for heart-type fatty acid-binding protein detection

Acute myocardial infarction (AMI) is a significant health problem owing to its high mortality rate. Heart-type fatty acid-binding protein (h-FABP) is an important biomarker in the diagnosis of AMI. In this work, an electrochemical h-FABP immunosensor was developed based on Cd0.5Zn0.5S/d-Ti3C2Tx MXene (MXene: Transition metal carbide or nitride) composite as signal amplificator and core-shell high-crystalline graphitic carbon nitride@carbon dots (hc-g-C3N4@CDs) as electrochemical sensor platform. Firstly, a facile calcination technique was applied to the preparation of hc-g-C3N4@CDs and immobilization of primary antibody was performed on he-g-C3N4@CDs surface. Then, the conjugation of the second antibody to Cd0.5Zn0.5S/d-Ti3C2Tx MXene was carried out by strong pi-pi and electrostatic interactions. The prepared electrochemical h-FABP immunosensor was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) method, Fourier-transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The prepared electrochemical h-FABP immunosensor indicated a good sensitivity with detection limit (LOD) of 3.30 fg mL(-1) in the potential range +0.1 to +0.5 V. Lastly, low-cost, satisfactory stable, and environmentally friendly immunosensor was presented for the diagnosis of acute myocardial infarction

A molecularly imprinted electrochemical biosensor based on hierarchical Ti2Nb10O29 (TNO) for glucose detection

A novel molecularly imprinted electrochemical biosensor for glucose detection is reported based on a hierarchical N-rich carbon conductive-coated TNO structure (TNO@NC ). Firstly, TNO@NC was fabricated by a novel polypyrrole-chemical vapor deposition (PPy-CVD) method with minimal waste generation. Afterward, the electrode modification with TNO@ NC was performed by dropping TNO@NC particles on glassy carbon electrode surfaces by infrared heat lamp. Finally, the glucose-imprinted electrochemical biosensor was developed in presence of 75.0 mM pyrrole and 25.0 mM glucose in a potential range from+ 0.20 to +1.20 V versus Ag/AgCl via cyclic voltammetry (CV). The physicochemical and electrochemical characterizations of the fabricated molecularly imprinted biosensor was conducted by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) method, X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and CV techniques. The findings demonstrated that selective, sensitive, and stable electrochemical signals were proportional to different glucose concentrations, and the sensitivity of molecularly imprinted electrochemical biosensor for glucose detection was estimated to be 18.93 RA mu M-1 cm(-2) ( R-2 = 0.99) = 0.99) at + 0.30 V with the limit of detection (LOD) of 1.0 x10(-6) M. Hence, it can be speculated that the fabricated glucose-imprinted biosensor may be used in a multitude of areas, including public health and food quality

A novel molecular imprinted QCM sensor based on MoS(2)NPs-MWCNT nanocomposite for zearalenone determination

Zearalenone (ZEN) is a mycotoxin that has a carcinogenic effect and is often found at a high rate in frequently consumed foods. In this study, a characteristic molecular imprinted quartz crystal microbalance (QCM) sensor based on molybdenum disulfide nanoparticle (MoS(2)NPs)-multiwalled carbon nanotube (MWCNT) nanocomposite (MoS(2)NPs-MWCNTs) is presented for selective determination of ZEA in rice samples. Firstly, molybdenum disulfide nanoparticle (MoS2NP)-multiwalled carbon nanotube nanocomposites were characterized by using microscopic, spectroscopic, and electrochemical techniques. Then, ZEA-imprinted QCM chip was prepared in the presence of methacryloylamidoglutamicacid (MAGA) as monomer, N,N'-azobisisobutyronitrile (AIBN) as initiator, and ZEA as target molecule by using UV polymerization. The sensor revealed a linearity toward ZEA in the range 1.0-10.0 ng L-1 with a detection limit (LOD) of 0.30 ng L-1. The high repeatability, reusability, selectivity, and stability of the developed sensor enable reliable ZEA detection in rice samples

L-Phenylalanine-Imprinted Electrochemical Sensor Based on WS2 Nanoflowers on N,B-Doped Graphene and Its Application to Milk Samples

Phenylketonuria (PKU) is a critical disease in the disorder of amino acid metabolism, which mostly emerges in children. The most common method used in PKU treatment is the detection of L-phenylalanine (PHEA) as the biomarker of PKU. In the present work, a new molecularly imprinted electrochemical electrode based on WS2 nanoflowers (NFs) on N,B-doped graphene (WS2 NFs/N,B-GR) is presented for PHEA assay in milk samples. First of all, WS2 NFs/N,B-GR was synthesized via a high-efficiency hydrothermal synthesis. Cyclic voltammetry was applied to the electrochemical cell, including PHEA as a template molecule and pyrrole as a monomer, to form PHEA-imprinted electrochemical electrodes. Then, the structural and morphological features of WS2 NFs and WS2 NFs/N,B-GR were investigated in detail by various analytical methods. The limit of quantification and limit of detection values were obtained as 1.0 × 10-11 and 3.0 × 10-12 M, respectively, by a PHEA-imprinted electrochemical electrode. Finally, a PHEA-imprinted electrochemical sensor having a high degree of selectivity, stability, and reusability is presented in the literature for early diagnosis of PKU. © 2022 American Chemical Society. All rights reserved

Sensitive sandwich-type electrochemical SARS-CoV-2 nucleocapsid protein immunosensor

A sensitive and fast sandwich-type electrochemical SARS-CoV-2 (COVID-19) nucleocapsid protein immunosensor was prepared based on bismuth tungstate/bismuth sulfide composite (Bi2WO6/Bi2S3) as electrode platform and graphitic carbon nitride sheet decorated with gold nanoparticles (Au NPs) and tungsten trioxide sphere composite (g-C3N(4)/Au/WO3) as signal amplification. The electrostatic interactions between capture antibody and Bi2WO6/Bi2S3 led to immobilization of the capture nucleocapsid antibody. The detection antibody was then conjugated to g-C3N(4)/Au/WO3 via the affinity of amino-gold. After physicochemically characterization via transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) analysis were implemented to evaluate the electrochemical performance of the prepared immunosensor. The detection of SARS-CoV-2 nucleocapsid protein (SARS-CoV-2 NP) in a small saliva sample (100.0 mu L) took just 30 min and yielded a detection limit (LOD) of 3.00 fg m(-1), making it an effective tool for point-of-care COVID-19 testing

Bisphenol a imprinted electrochemical sensor based on graphene quantum dots with boron functionalized g-c3n4 in food samples

A molecular imprinted electrochemical sensor based on boron-functionalized graphitic carbon nitride (B-g-C3N4) and graphene quantum dots (GQDs) was presented for selective determination of bisphenol A (BPA). In particular, by combining the selectivity and high stability properties, which are the most important advantages of molecular imprinted polymers, and the highly sensitive properties of GQDs/B-g-C3N4 nanocomposite, a highly selective and sensitive analytical method was developed for BPA analysis. Firstly, GQDs/B-g-C3N4 nanocomposite was characterized by using microscopic, spectroscopic, and electrochemical techniques. This novel molecular imprinted electrochemical sensor for BPA detection demonstrated a linearity of 1.0 x 10(-11)-1.0 x 10(-9) M and a low detection limit (LOD, 3.0 x 10(-12) M). BPA-imprinted polymer on GQDs/B-g-C3N4 nanocomposite also showed good stability, repeatability and selectivity in food samples

Defect assisted optical limiting performance of hexagonal boron nitride nanosheets in aqueous suspension and PMMA nanocomposite films

Defect-assisted nonlinear absorption (NLA) and optical limiting (OL) performance of hexagonal boron nitride nanosheets (h-BNNS) in aqueous suspension and in polymethyl methacrylate matrix (PMMA) as nanocomposite films were studied using open-aperture Z-scan method. To evaluate the transmission in open-aperture Z-scan data, a theoretical model accounting one photon absorption (OPA), two photon absorption (TPA), free carrier absorption (FCA) and saturation of each process was considered. Defect-assisted NLA coefficients and saturation intensity thresholds were extracted from the fitting of the experimental results for 532 and 1064 nm pulse wavelengths. Strong defect-assisted NLA response of h-BNNS was observed while NLA at 532 nm was considerably stronger. This is attributed to the excitation of a greater number of defect states over a wider energy range. Our findings showed that h-BNNS/PMMA nanocomposite films feature highly required properties in OL applications and can function in OL applications in a wide spectral range (-200-1064 nm)