Ultrasensitive and Selective Determination of Carcinoembryonic Antigen Using Multifunctional Ultrathin Amino-Functionalized Ti3C2-MXene Nanosheets

Herein, we report on a two-dimensional amino-functionalized Ti3C2-MXene (N–Ti3C2-MXene)-based surface plasmon resonance (SPR) biosensor for detecting carcinoembryonic antigen (CEA) utilizing a sandwich format signal amplification strategy. Our biosensor employs an N-Ti3C2-MXene nanosheet-modified sensing platform and a signal enhancer comprising N-Ti3C2-MXene-hollow gold nanoparticles (HGNPs)-staphylococcal protein A (SPA) complexes. Ultrathin Ti3C2-MXene nanosheets were synthesized and functionalized with aminosilane to provide a hydrophilic-biocompatible nanoplatform for covalent immobilization of the monoclonal anti-CEA capture antibody (Ab1). The N-Ti3C2-MXene/HGNPs nanohybrids were synthesized and further decorated with SPA to immobilize the polyclonal anti-CEA detection antibody (Ab2) and serve as signal enhancers. The capture of CEA followed by the formation of the Ab2-conjugated SPA/HGNPs/N-Ti3C2-MXene sandwiched nanocomplex on the SPR chip results in the generation of a response signal. The fabri...