Functional monomer-template-QDs sandwich structure for mesoporous structured bovine hemoglobin imprinted ratiometric fluorescence sensor.

In this work, mesoporous structured molecularly imprinted ratiometric fluorescence sensor (M-R-MIPs) for highly sensitive and selective determination of bovine hemoglobin (BHb) was developed based on core-shell structure. First, red CdTe QDs were embedded into silica nanoparticles by reverse microemulsion method, then BHb imprinted silica shell were coated on the core silica. In order to improve the sensitivity of the as-prepared MIPs sensor, during the process of imprinted silica shell formation, functional monomer-template-QDs sandwich structure was first employed to improve the recognition sites accessibility, mesoporous silica was applied to reduce mass transfer resistance, and ratiometric fluorescence technique was adopted to achieve visual signal output by doping green CdTe QDs into silica shell. The as-prepared M-R-MIPs exhibited excellent sensitivity when compared to M-R-NIPs and corresponding single fluorescence MIPs sensor. Under the optimized condition, when detection of BHb, the linear range was 0.02-2.0μM with detection limit of 6.3nM, accompanied with distinguished fluorescence color change from yellow to orange to red. The feasibility of the developed method in real samples was successfully evaluated through analysis of BHb in bovine urine and blood samples with satisfactory recoveries of 92.6-101.2%. The developed method proposed in this work proved to be more sensitive and reliable, provided an alternative solution for recognition and determination of protein from real samples.