A highly sensitive peptide-based biosensor using NiCo2O4 nanosheets and g-C3N4 nanocomposite to construct amplified strategy for trypsin detection.

Here, a simple electrochemical biosensor was proposed based on the specific recognition between trypsin and peptide. Initially, NiCo2O4-PAMAM nanocomposite was casted on the bare electrode to achieve the electrochemical signal amplification in 0.1 mM [Ru(NH3)6]3+ solution owing to the great electronic conductivity and high electrochemical activity induced by the special structure of NiCo2O4 nanosheets (Ni3+ cations in octachedral sites of the Co3O4). Subsequently, a declined electrochemical signal was obtained when g-C3N4 labeled peptide composites were anchored on the electrode. However, after trypsin was added into solution and incubated with the biosensor, the electrochemical signal was re-promoted. Therefore, the as-synthesized biosensor could realize the sensitive detection of trypsin by virtue of the specific recognition between trypsin and peptide. As a result, the developed peptide-based exhibited a linear range from 10-10 to 10-4 mg mL-1 with an ultralow detection limit of 10-10 mg mL-1, providing sensitive analytical performance and acceptable application potential in clinical test and disease diagnosis due to its high stability, excellent selectivity, acceptable reproducibility and accurate signal output.