A dual epitope-imprinted polymer@AuNP-MoS2 nanosheets-EQCM sensor for antibody free detection of SipD protein of Salmonella typhi bacteria with high selectivity

Dual-epitope imprinted EQCM sensor for selective and sensitive detection of Salmonella typhi bacterial protein is fabricated on gold nanoparticle decorated MoS 2 nanosheets (AuNPs-MoS 2 NSs). Salmonella invasive protein D (SipD) binds to the needle protein and appears capable of interacting with the translocon complex to infect the host. Potential B cell antigenic epitope sequences from bacterial tip protein, SipD were intentionally tagged with cysteine and are used as dual templates to fabricate MIP sensor using methacryloyloxyethyl phosphorylcholine (MPC), benzyl methacrylate (BMA) and methacrylic acid (MAA) as monomers and N , N ′-methylene- bis -acrylamide as a crosslinker. The monomers chosen through docking produced a DEIP-EQCM sensor. The sensor was able to show specific binding towards the blood samples of infected patients, even in the presence of ‘matrix’ of ‘real’ samples and other plasma proteins. It has shown excellent specificity, sensitivity and selectivity in sensing range of 100–1000 nM with detection limit 1.65 nM (Epitope I) and 0.025 nM (Epitope II) and limit of quantification as 5.03 nM (Epitope I) and 0.075 nM (Epitope II) for the two epitope sequences imprinted. Sip D protein binding was substantiated by SDS-PAGE analysis. The repetitive experimental runs could not mutilate the specific geometries of respective imprinted cavities and the DEIP-EQCM sensor can be proposed for antibody free detection of Sip D protein. • Antibody free detection of SipD protein of Salmonella typhi bacteria through dual epitope-imprinted polymer@AuNP-MoS 2 nanosheets-EQCM sensor. • Designed through computer aided molecular docking extending excellent selectivity with high specificity and sensitivity with LOD in nanomolar range. • Real-time sensing in ‘real’ samples of patients substantiated by SDS-PAGE analysis.