CdSe quantum dot-encapsulated molecularly imprinted mesoporous silica particles for fluorescent sensing of bisphenol A

We prepared a highly sensitive molecularly imprinted fluorescent sensor by using a CdSe quantum dot (QD) as a signal transducer and a mesoporous silica nanoparticle as an imprinting material. Bisphenol-A (BPA) was chosen as a model template, which is known as an endocrine disruptor. Binding sites were selectively formed between the pores and CdSe QDs were encapsulated in the pores of the mesoporous silica. QD-encapsulated, molecularly imprinted mesoporous silica (QD-MIMS) particles exhibited excellent molecular recognition properties in terms of both sensitivity and selectivity. Owing to the proximity of the binding sites to the QDs, a significant, concentration-sensitive fluorescence quenching was observed in the presence of BPA. QD-MIMS showed a linear Stern-Volmer relationship for BPA and its analogs. QD-MIMS had a much larger quenching constant for BPA (by more than ten times) than for BPA analogs, demonstrating the high selectivity of QD-MIMS.