A Ti3C2-MXene-functionalized LRSPR biosensor based on sandwich amplification for human IgG detection

Long-range surface plasmon resonance (LRSPR) has demonstrated excellent performance in sensing and detection, due to its higher accuracy and sensitivity compared with conventional surface plasmon resonance (cSPR). In this work, we establish an LRSPR biosensor which employs PDA/Ti 3 C 2 -MXene/PDA-gold film as a sensing substrate and gold nanoparticles (AuNPs) as enhancers. Ti 3 C 2 -MXene is an emerging two-dimensional (2D) layered material which is used extensively in immunoassay and biosensing. The sensing substrate comprises two polydopamine (PDA) films between which is sandwiched a Ti 3 C 2 -MXene film based on a gold film, which provides a large surface area and abundant binding sites to rabbit anti-human IgG (Ab 1 ). Sandwich amplification is adopted to enhance the sensitivity of the LRSPR biosensor, and AuNPs/staphylococcal protein A (SPA)/mouse anti-human IgG (Ab 2 ) composites are introduced into the flow cell as enhancers after the immune binding of human IgG to Ab 1 . The antigen (human IgG) detection range is 0.075 μg mL −1 to 40 μg mL −1 , and the limit of detection is almost 20 times lower than that for cSPR biosensors. This novel LRSPR biosensor demonstrates excellent performance in immune sensing over a broad detection range and a low limit of detection. Subsequent modification of the LRSPR sensing platform could be made for extensive application in various biological detection fields. Graphical abstract