Preparation and properties of boron affinity molecularly imprinted mesoporous polymers based on Mn-doped ZnS quantum dots

Sialic acid (SA), known as N-acetyl neuraminic acid, is a natural 9-carbomonosaccharide derivative. SA has been widely applied in the early diagnosis of diseases as therapeutic target. However, the abundance of SA is very low in biological samples, which is usually interfered by the similar molecules coexisting at high abundance. Combining the advantages of high selectivity and specificity of molecularly imprinted technology, high specific surface area of mesoporous materials and excellent optical properties of quantum dots, we chose Mn-doped ZnS quantum dots as signal elements, and sialic acid as the template molecule. KH-4-MAPB with recognition ability to SA was synthesized by one-step hydrothermal method using thiolene click reaction as functional monomer. Based on the principle of boron affinity, molecularly imprinted polymers with highly ordered mesoporous structure were prepared, and the structure and fluorescence properties of fluorescent molecularly imprinted polymers were studied. FT-IR, XRD, TEM and nitrogen adsorption-desorption experiments were used to characterize the structure and morphology of the molecularly imprinted polymers. The results showed that the prepared molecularly imprinted polymers had highly ordered mesoporous structure and a large number of imprinted holes, which ensured the specific selectivity of the molecularly imprinted polymers. The fluorescence properties of MIMPs were characterized and analyzed by fluorescence spectra, equilibrium adsorption kinetics experiments were conducted and imprinting properties were recorded under different pH. The above experimental results showed that the fluorescence quenching was successfully achieved when the template molecule SA was captured by the molecularly imprinted polymer. When the concentration of SA was 1.25-100 × 10-2 g/L, the fluorescence quenching degree of MIMPs showed a fine linear relationship with SA. The correlation coefficient was 0.9946, and the detection equation was F0/F - 1 = 0.0215 [CSA] + 0.0241. MIMPs had a high recognition ability for SA, and the imprinting factor was 2.44. As a fluorescent sensor for SA, the response time of MIMPs was 20 min. When the buffer solution pH was 7, the imprinting factor was the largest. Under the best conditions, MIMPs revealed good selectivity and specificity for the fluorescence recognition of SA. MIMPS were also applied to the analysis of SA in real human serum samples with satisfactory results.