Synthesis of Au-decorated boron nitride nanotubes and its application to pretreatment-free electrochemical biosensor for matrix metalloproteinase9 in clinical sample

As matrix metalloproteinase-9 (MMP-9) is a biomarker for several diseases such as inflammatory, cardiovascular, and lung diseases, determining its level in human serum is vital for the detection of such diseases. However, accurately detecting MMP-9 in serum requires a time-consuming and expensive pre-treatment process with fil-ters. To minimize the diagnosis process, the authors constructed a pre-treatment-free electrochemical biosensor for determining MMP-9 in clinical sample. To fabricate the biosensor, Au-decorated boron nitride nanotubes (Au@BNNTs) were synthesized to improve the sensor's performance. The synthesis of Au@BNNTs was confirmed through transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), and Fourier-transform infrared spectroscopy (FT-IR) experiments. Then, the MMP-9 aptamer was immobilized on the Au@BNNTs-modified round Au micro-gap integrated printed circuit board (PCB) chip. The electrochemical biosensor's performance was validated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Based on this, the electrochemical signal amplification ability of Au@BNNTs is confirmed, and its potential is demonstrated. In addition, the fabricated biosensor can detect the MMP-9 in 100% human serum. The linear detection range test yielded a wider concentration range (0.1-10,000 ng center dot mL-1) and a lower limit of detection (0.0218 ng center dot mL-1) for MMP-9 compared to previous research. Finally, through a selectivity test and clinical patient sample test, it is confirmed that the proposed biosensor specifically detects only MMP-9 well. The pro-posed Au@BNNT biosensor with aptamer has potential applications in MMP-9 detection and diagnosis of various diseases without the need for pretreatment.