Fluorescent molecularly imprinted membranes as biosensor for the detection of target protein

Combining quantum dots with molecular imprinting techniques, a fluorescent molecularly imprinted membrane (MIM) is prepared by embedding L-cysteine-capped Mn²⁺-doped ZnS quantum dots (QDs) into molecularly imprinted polymer matrix. This fluorescent MIM is used as biosensor for specific recognition of a target protein (lysozyme). The key point of this approach is that the fluorescent quantum dots embedded into a molecularly imprinted membrane, which enables the optical readout characteristic and high selectivity within a thin hydrogel membrane. When the fluorescent MIM selectively captures the target protein, the electron transfer between the QDs and the target protein will result in the fluorescence quenching of the membrane. And the quenched fluorescence emission intensity was proportional to the concentration of the analytes. The as-prepared membrane was successfully applied to selectively and sensitively detect target proteins without any time-consuming pretreatments. Under optimal conditions, the linear detection of the fluorescence MIM ranged from 1.0 × 10⁻⁷ to 1.0 × 10⁻⁶ mol L⁻¹ with the detection limit of 10.2 nM. Furthermore, the MIM was applied to determine lysozyme in real samples with recoveries of 93%–103%. Experimental results showed that the fluorescent MIM might serve as a simple and sensitive fluorescent biosensor for detecting target protein in complex biological samples.