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, NiCo 2 O 4 -PAMAM nanocomposite was casted on the bare electrode to achieve the electrochemical signal amplification in 0.1 mM [Ru(NH 3 ) 6 ] 3+ solution owing to the great electronic conductivity and high electrochemical activity induced by the special structure of NiCo 2 O 4 nanosheets (Ni 3+ cations in octachedral sites of the Co 3 O 4 ). Subsequently, a declined electrochemical signal was obtained when g-C 3 N 4 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.