Highly sensitive and label-free detection of influenza H5N1 viral proteins using affinity peptide and porous BSA/MXene nanocomposite electrode.

Influenza viruses are known to cause pandemic flu through inter-human and animal-to-human transmissions. Neuraminidase (NA), which is a surface glycoprotein of both influenza A and B viruses, is a minor immunogenic determinant; however, it has been proposed as an ideal candidate for a real testing. We successfully identified an affinity peptide which is specific to the influenza H5N1 virus NA via phage display technique and observed initially its binding affinities using enzyme-linked immunosorbent assay (ELISA). In addition, four synthetic peptides were chemically synthesized to develop an affinity peptide-based electrochemical biosensing system. Among all peptides tested, INA BP2 was selected as a potential candidate and subjected to square-wave voltammetry (SWV) for evaluating their detection performance. To enhance analytical performance, a three-dimensional porous bovine serum albumin (BSA)-MXene (BSA/MXene) matrix was applied. The surface morphology of the BSA/MXene film-deposited electrode was analyzed using X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Using SWV measurement, the BSA/MXene nanocomposite-based peptide sensor exhibited significant the dissociation constant (K = 9.34 ± 1.20 nM) and the limit of detection (LOD, 0.098 nM), resulting in good reproducibility, stability and recovery, even in the presence with spiked human plasma. These results demonstrate an alternative way of new bioanalytical sensing platform for developing more desirable sensitivity in other virus detection.