Molecularly Imprinted Polymer Biosensor Based on Nitrogen-Doped Electrochemically Exfoliated Graphene/Ti3 CNTX MXene Nanocomposite for Metabolites Detection.

Rapid and accurate quantification of metabolites in different bodily fluids is crucial for a precise health evaluation. However, conventional metabolite sensing methods, confined to centralized laboratory settings, suffer from time-consuming processes, complex procedures, and costly instrumentation. Introducing the MXene/nitrogen-doped electrochemically exfoliated graphene (MXene@N-EEG) nanocomposite as a novel biosensing platform in this work addresses the challenges associated with conventional methods, leveraging the concept of molecularly imprinted polymers (MIP) enables the highly sensitive, specific, and reliable detection of metabolites. To validate our biosensing technology, we utilize agmatine as a significant biologically active metabolite. The MIP biosensor incorporates electrodeposited Prussian blue nanoparticles as a redox probe, facilitating the direct electrical signaling of agmatine binding in the polymeric matrix. The MXene@N-EEG nanocomposite, with excellent metal conductivity and a large electroactive specific surface area, effectively stabilizes the electrodeposited Prussian blue nanoparticles. Furthermore, increasing the content of agmatine-imprinted cavities on the electrode enhances the sensitivity of the MIP biosensor. Evaluation of the designed MIP biosensor in buffer solution and plasma samples reveals a wide linear concentration range of 1.0 nM-100.0 µM (R2 = 0.9934) and a detection limit of 0.1 nM. Notably, the developed microfluidic biosensor offers low cost, rapid response time to the target molecule (10 min of sample incubation), good recovery results for detecting agmatine in plasma samples, and acceptable autonomous performance for on-chip detection. Moreover, its high reliability and sensitivity position this MIP-based biosensor as a promising candidate for miniaturized microfluidic devices with the potential for scalable production for point-of-care applications.

Stability improvement of polyaniline nanocomposite immunosensor for early detection of insulin receptor antibody as biomarker of type 2 diabetes.

Polyaniline nanocomposite with controllable properties was used to design and fabricate a novel electrochemical immunosensor for the early detection of type 2 diabetes. Insulin receptor antibody is a powerful predictor of type 2 diabetes development in individuals. A systematic study was carried out to investigate the effects of different polyaniline layers and the Nafion layer on the morphological, chemical, and electrochemical properties of nanocomposite immunosensor, especially the stability. The bioengineered Nafion-Au nanoparticles-polyaniline/gold electrode demonstrated outstanding electrocatalytic performance in the detection of insulin receptor antibodies with a high sensitivity (136.21 µA.ng-1.ml.cm-2) in a linear range from 0.001 to 200 ng.ml-1 as well as a low detection limit of 1.827 pg.ml-1, response time within 10 min, remarkable selectivity, and significant stability of 80 days. Therefore, the developed immunosensor is a suitable nanocomposite platform for insulin receptor antibody level determination in human plasma.

Ultrasensitive early detection of insulin antibody employing novel electrochemical nano-biosensor based on controllable electro-fabrication process.

An ultrasensitive novel electrochemical nano-biosensor for rapid detection of insulin antibodies against diabetes antigens was developed in this research. The presence of insulin antibodies has been demonstrated to be a strong predictor for the development of type 1 diabetes in individuals who do not have diabetes but are genetically predisposed. The proposed nano-biosensor fabrication process was based on the optimized sequential electropolymerization of polyaniline and electrodeposition of gold nanoparticles on the surface of the functionalized gold electrode. The morphological and chemical characterization of the modified electrode was studied by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and micro Raman spectroscopy. Moreover, the role of each component in the modification of the electrode was studied by electrochemical methods systematically. After immobilizing insulin antigen and blocking with bovine serum albumin, the nano-biosensor was used for determining different concentrations of insulin antibody under the optimal conditions. This nano-biosensor could respond to insulin antibody with a linear calibration range from 0.001 ng ml-1 to 1000 ng ml-1 with the detection limit of 0.017 pg ml-1 and 0.034 pg ml-1 and selectivity of 18.544 µA ng-1 ml.cm-2 and 31.808 µA ng-1 ml.cm-2 via differential pulse voltammetry and square wave voltammetry, respectively. This novel nano-biosensor exhibited a short response time, high sensitivity, and good reproducibility. It was successfully used in determining the insulin antibody in human samples with a standard error of less than 0.178. Therefore, the nano-biosensor has the potential for the application of early detection of type 1 diabetes. To our best knowledge, label-free electrochemical detection of insulin antibody based on immunosensor is developed for the first time.