A novel label-free electrochemical immunosensor based on DCNC@AgNPs/ MXene for the detection of apolipoprotein A-1 in human serum

Cellulose nanocrystals (CNCs), a class of stable natural substances, have been extensively employed as a substrate material, because of their enormous specific surface area and great biocompatibility. Additionally, CNCs demonstrated that they possess required attributes to serve as chemically reactive biotemplate for the synthesis of metallic nanoparticles. Two dimensional (2D) layered matrials used in the formation of nanocompoistes have showed intriguing potential for generating highly effective electrochemcial immunosre. In this regard, we employed dialdehyde cellulose nanocrystal (DCNC) as a reducing and stabilizing agent, to propose an efficient method for generating stable silver nanoparticles (AgNPs). Secondly, to synthesize silver-functionalized MXene, this unique DCNC-stabilized AgNPs has been incorporate on to the surface of MXene. Finally, this innovative nanocompsite (DCNC-Ag-MXene) was used to construct an electrochemical immunosensor for the effective detection of APO-A1 using differential pulse voltammetry (DPV) in 5 mM K3 [Fe(CN6)]/K4 [Fe(CN6)] as a redox probe. The proposed immunosensor that integrated the unique electrocatalytic characteristics and synergistic effect between MXene and AgNPs not only promoted the electron transfer, but also increased the available surface area for apolipoprotein A-1 (APO-A1) detection. Under the optimal conditions, the fabricated immunosensor exhibited higher sensitivity to APO-A1 with a linear range of 0.01 pg/mL to 1000 pg/mL and limit of detection (LOD) of 2.20 fg/ml. Furthermore, the constructed biosensor showed acceptable selectivity, high repeatability, and excellent stability. The practicaity of this immunosensor was vailidated by assesing APO-A1 in human serum samples with recovery rates of 97.87-104.67%.