A novel approach for amine derivatization of MoS₂ nanosheets and their application toward label-free immunosensor

The application of molybdenum disulfide (MoS₂) nanosheets has assumed great significance in the design of next-generation biosensors. The immobilization of biomolecules on MoS₂ nanosheets has generally been achieved via hydrophobic interactions or through other complicated surface modifications. In this work, we report a novel strategy for electrochemically assisted amine derivatization of MoS₂ nanosheets. This newly proposed approach helped to immobilize the MoS₂ nanosheets with antibodies via facile EDC/NHS {N-(3-dimethylaminopropyl)-N-(ethylcarbodiimide/N-hydroxysuccinimide)} cross-linking chemistry. The MoS₂ nanosheets were first exfoliated and then electrochemically modified with 2-aminobenzylamine. Through a subsequent bioconjugation of the above amine-derivatized MoS₂ nanosheets with anti-prostate-specific antigen (PSA) antibodies, an immunosensing device was realized for the detection of the 'prostate specific antigen'. The application of the proposed immunosensor was characterized with a low detection limit (10^-3 ng/mL) over a very wide quantitation range (10^-3 to 200 ng/mL).