Preparation of ZnS-Carbon nanotube nanocomposites via solvothermal method and their application in electrochemical detection of escherichia coli O157:H7

In this study, hierarchical ZnS–CNT hybrids were synthesized via a solvothermal reaction at 180 °C for 48 h, producing ∼200 nm ZnS spheres uniformly anchored onto oxidized multiwalled carbon nanotubes. Structural analyses by XRD confirmed the cubic sphalerite phase, while SEM and TEM revealed a “pearl-necklace” morphology and effective nanoparticle dispersion. XPS spectra verified Zn2+ and oxygen-containing surface groups on the composite. Nitrogen adsorption–desorption measurements showed that incorporating CNTs transformed the material’s isotherm from type III to type IV, increasing the BET surface area from 68 to 155 m2 /g and introducing mesoporosity. When drop-cast onto screen-printed electrodes and functionalized via streptavidin–biotin chemistry, the platform exhibited a concentration-dependent increase in charge-transfer resistance for E. coli O157:H7 across 103 –108 CFU/mL, achieving a limit of detection of ~103CFU/mL within a 30 min incubation. Specificity assays against Salmonella enteritidis, Listeria monocytogenes, and Staphylococcus aureus demonstrated negligible cross-reactivity. The rapid response, low-cost fabrication, and high surface area afforded by the mesoporous architecture highlight the composite’s potential for on-site, real-time pathogen screening in food safety and environmental monitoring applications.