Exploration of a polymer responsive potentiometric biosensor for the detection of flagella and whole cell of Proteus mirabilis: proof-of-concept

Identifier:  imarina:9468496

Handle: https://hdl.handle.net/20.500.11797/imarina9468496

Authors:  Khan, M Azizur R; Cervellera-Dominguez, A; Sales, M Goreti F; Riu, Jordi

Abstract:
This work presents a novel biosensor based on molecularly imprinted polymers (MIP) to detect the flagella of Proteus mirabilis and describes experiments of the response to the whole bacterial cell. The MIP was obtained directly on the surface of gold electrodes, by electropolymerisation of pyrrole in the presence of Proteus mirabilis flagella, using cyclic voltammetry. The imprinted polymer matrix was then treated with trypsin to enzymatically digest the flagella and expose the complementary cavities that served as selective recognition sites. The performance of the electrodes prepared with the MIP materials and the corresponding controls was evaluated by potentiometric assays in HEPES buffer. This was performed for the flagella of Proteus mirabilis and the whole cell of the bacterium. The limit of detection (LOD) for flagella was 0.251 mu g/mL with the MIP and 0.758 mu g/mL with the control non-imprinted polymer (NIP). The imprinting factor (IF) demonstrated concentration-dependent enhancement of specific binding, with IF values of about 2.05 at 11.10 ng/mL, 7.30 at 111.10 ng/mL, and 13.60 at 311.10 ng/mL. Additionally, the slope of the NIP calibration curve was found to be lower than that of the MIP, further confirming that the sensitivity arises from the imprinted cavities. To confirm the preference of the material for the flagella, selectivity studies were performed against other non-target proteins, including glucose oxidase, Staphylococcus aureus protein A and bovine serum albumin. Overall, the results showed good sensitivity and high selectivity for Proteus mirabilis flagella, emphasising the promising potential of this MIP-based sensor for the rapid and cost-effective detection of bacterial proteins. However, the detection of the whole cell under the tested conditions remained limited. This could be due to the cell's ability to move, as it has flagella and its driving force for movement is likely higher than the binding affinity for the MIP, which relies only on non-covalent bonds.