QDs embedded copolymer nanospheres prepared with a simple self-stable precipitation polymerization method for Listeria monocytogenes detection

Abstract In this paper, a simple self-stable precipitation polymerization method was used to prepare fluorescent quantum dots (QDs) embedded styrene-maleic anhydride copolymer nanospheres. Compared with conventional polymerization process, we only need to dissolve hydrophobic QDs, styrene, maleic anhydride, and initiator in cyclohexane/isoamyl acetate mixed solvent and implemented the polymerization process without requiring any stabilizers, surfactants, and continuous stirring. The most important influence parameter on the internal structure of QDs embedded nanospheres, such as cyclohexane/isoamyl acetate volume ratio was systematically investigated. After hydrolysis, the obtained nanospheres were functionalized with carboxyl groups, which could be conjugated with antibodies to capture target proteins in a sandwich assay format. Using Listeria monocytogenes as a model biomarker in a lateral flow immunoassay (LFIA) detection system, we achieved a detection limit of as low as 104 CFU/mL, which is at least one log lower than conventional LFIA.