Imprinted Sol-gel Film Research Articles

Stereoselective histidine sensor based on molecularly imprinted sol-gel films

A piezoelectric sensor coated with a thin molecularly imprinted sol-gel film has been developed for the determination of l-histidine in the liquid phase. Without preprotection, l-histidine was imprinted directly into silica sol-gel films that consisted of a hybrid mixture of functionalized organosilicon precursors (phenyltrimethoxysilane and methyltrimethoxysolane). The viscoelasticity of the film in the air and in buffer solution has been studied by the piezoelectric quartz crystal impedance technique. The binding of l-histidine to the imprinted film in the liquid phase was investigated by the piezoelectric microgravimetry and electrochemical impedance technique. Scatchard analysis showed that the maximum binding site ( Q max) of the l-histidine imprinted sol-gel film is about 23.7 μmol/g. A linear range from 5.0 × 10 −8 to 1.0 × 10 −4 M for a detection of l-histidine has been observed with a detection limit of 2.5 × 10 −8 M for S/N = 3. The proposed imprinted sol-gel sensor exhibits good stability, high specificity, and excellent stereoselectivity.

Assessment of molecularly imprinted sol–gel materials for selective room temperature phosphorescence recognition of nafcillin

Sol–gel imprinted materials were prepared against nafcillin, a semisynthetic β-lactamic antibiotic employed in the treatment of serious infections caused by penicillinase-producing staphylococci. Two approaches were addressed for preparation of the imprinted materials and the controls: as conventional monoliths, which were ground and sieved to a desired particle size for rebinding analysis, and as films on supporting glass slides. The specific binding sites that are created during the imprinting process are analyzed via selective room temperature phosphorescence (RTP) (sol–gel films) measurements as well as via competitive room temperature phosphorescence ligand assay. Results demonstrated the importance of the physical configuration of the imprinted material for minimizing non-specific binding. The close similarities between the structures of different β-lactamic antibiotics made it possible to interpret the roles of the template structure on specific molecular recognition. In this article, we introduce the use of room temperature phosphorescence as selective transduction method for the template. The imprinted sol–gel films displayed enhanced specific binding characteristics respect to the monolithic sol–gel and can be envisaged for the use as recognition matrices for the screening and rapid selection of antibiotics from a combinatorial library or for the rapid control of nafcillin in biological samples (e.g. milk, serum, urine).