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Comparative syntheses of tetracycline-imprinted polymeric silicate and acrylate on CdTe quantum dots as fluorescent sensors

2014; Elsevier BV; Volume: 61; Linguagem: Inglês

10.1016/j.bios.2014.05.058

1873-4235

Mu‐Rong Chao, Chiung‐Wen Hu, Jian‐Lian Chen,

Advanced biosensing and bioanalysis techniques

The amphoteric drug molecule tetracycline, which contains groups with pKa 3.4–9.9, was used as a template for conjugating molecularly imprinted polymers (MIPs) and as a quencher for CdTe quantum dot (QD) fluorescence. Two MIP–QD composites were synthesized by a sol–gel method using a silicon-based monomer and a monomer linker between the MIP and QD, i.e., tetraethoxylsilane/3-mercaptopropyltriethoxysilane (MPS) and tetraethoxylsilane/3-aminopropyltriethoxysilane (APS). Another MIP–QD composite was synthesized by the chain-growth polymerization of methacrylic acid (MAA) and an allyl mercaptan linker. The prepared MIP–QDs were characterized by FTIR and SEM and utilized at 0.33 mg/mL to determine the tetracycline content in phosphate buffers (pH 7.4, 50 mM) through the Perrin and Stern−Volmer models of quenching fluorometry. The Perrin model was applied to tetracycline concentrations of 7.4 μM–0.37 mM for MIP–MPS–QD, 7.4 μM–0.12 mM for MIP–APS–QD, and 7.4 μM–0.10 mM for MIP–MAA–QD (R2=0.9988, 0.9978, and 0.9931, respectively). The Stern−Volmer model was applied to tetracycline concentrations of 0.12–0.37 mM for MIP–APS–QD (R2=0.9983) and 0.10–0.37 mM for MIP–MAA–QD (R2=0.9970). The detection limits were 0.45 μM, 0.54 μM, and 0.50 μM for MIP–MPS–QD, MIP–APS–QD, and MIP–MAA–QD, respectively. Equilibrium times, differences between imprinted and nonimprinted polymers, and MIP–QD quenching mechanisms were discussed. Finally, specificity studies demonstrated that MIP–MAA–QD exhibited optimal recoveries of 96% from bovine serum albumin (n=5, RSD=3.6%) and 91% from fetal bovine serum (n=5, RSD=4.8%).