A sensitive and selective electrochemical sensing strategy based on Nb₂CT_x nanoplate-supported bacteria imprinted polymer

The rapid and sensitive detection of Staphylococcus aureus (S. aureus), a Gram-positive bacterium responsible for a wide range of infections, at a low cost, is crucial for diagnosing bacterial infections. In this protocol, an Nb₂CT_x MXene nanoplate (Nb₂CT_x NP)-supported bacteria-imprinted polymer (BIP)-based electrochemical sensor was proposed for the highly sensitive detection of bacteria. The BIP sensor was designed using an electropolymerization (EP) approach on a glassy carbon electrode (GCE) using S. aureus as a template and p-aminobenzoic acid (p-ABA) as a functional monomer. By integrating Nb₂CT_x NP, the BIP-based electrochemical sensor's active surface area and porosity were increased. The designed BIP-based electrochemical sensor achieved a wide detection range of 10°–10⁴ CFU mL⁻¹ and a low detection limit (LOD) of 0.095 log [CFU mL⁻¹]. Moreover, the determination of S. aureus with high selectivity in the presence of Gram-negative and positive bacteria showed that the sensor has excellent analytical performance. Both the electrochemical and morphological characterizations of the S.aureus/p-ABA/Nb₂CT_x NP/BIP-GCE sensor were evaluated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and scanning electron microscopy (SEM). The developed sensor exhibited excellent repeatability and reproducibility, with relative standard deviations ranging from 0.41 % to 1.93 % in both standard and urine solutions. In addition, the sensor exhibited high specificity, successfully distinguishing S. aureus from Gram-negative (Escherichia coli and Klebsiella pneumoniae), Gram-positive (Enterococcus faecalis and Bacillus subtilis), uric acid, and their mixtures. The applicability of this approach to detect bacteria in complicated samples shows that it has tremendous potential in public health-related domains. Also, the study's green profile was assessed using multiple evaluation tools, including the Blue Applicability Grade Index (BAGI), the Analytical Greenness Assessment Tool for Molecularly Imprinted Polymer Synthesis (AGRREMIP), the Analytical Greenness Metric (AGREE), and the Analytical Greenness Preparation Tool (AGREEprep).