Studies on the Preparation and Properties of Sol–Gel Molecularly Imprinted Polymer Based on Tetramethoxysilane and Methyltrimethoxysilane for Recognized Sulfonamides

Abstract

The synthesis of a molecularly imprinted polymer (MIP) composed of tetramethoxysilane (TMOS) and methyltrimethoxysilane (MTMOS) for recognized sulfonamides by sol-gel process has been investigated. The MIP's preparation conditions, the H 2 O/Si molar ratios (R), pH value of competition solution, calcination temperature, and the TMOS and MTMOS molar fractions are discussed. Adsorption and selectivity in different pH solutions were determined by competition experiments between the MIP template (sulfamethazine, SMZ) and the analogue (sulfamethoxazole, SMO) using High-Performance Liquid Chromatography (HPLC). The results show that the selectivity of the MIP in competition solution with pH ¼ 7:4 was higher than that with pH ¼ 4:6. In addition, the second stage temperature of calcination, which was carried out at 375 C, was obtained high selectivity. Moreover, the selectivity of the MIP (10.5) was approximately 3.5 times greater than the nonimprinted polymer (3.72) under the optimum preparation conditions. KEY WORDS: Molecularly Imprinted Polymer / Sulfonamide / Sol-Gel / Sulfamethazine / Sulfamethoxazole / HPLC / Molecular recognition is a phenomenon that can be envisaged as the preferential binding of a molecule to a ''receptor'' with high selectivity over its close structural analogues. This concept has been translated elegantly into the technology of molecular imprinting, which allows specific recognition sites to be formed in synthetic polymers through the use of various templates.1-5 Molecular imprinting of synthetic polymers with a specific target molecule can be done if the target resembles the template or imprint molecule used during polymerization and then removed after polymerization. Polymerization occurs when monomers carrying certain functional groups interact with the template and arrange themselves around the template into a 'frozen' position.6-9 Imprinting has been achieved by three ways; non-covalent, covalent and sacrificial spacer. Non-covalent imprinting relies on the ability of the template molecule to produce one or more strong intermolecular non-covalent interactions with the functional monomers, e.g., H-bonding, electrostatic or -interactions. Removal of the template affords a cavity, which is complementary in size shape and functionality to the template molecule, and which contains the recognition site used for recognizing specific molecules. In covalent imprinting, the template-monomer covalent bond is formed before the polymerization of MIP. Polymerization is conducted in the usual manner but template removal and rebinding is achieved by a chemical rather than physical process. 10 In the sacrificial spacer method, the pre-organized or covalent approach employs reversible covalent bonds, usually involving a prior chemical synthesis step to link the precursors to the template or to a structurally similar molecule.9 In other words, monomers are covalently linked to the template via short spacers. The spacers are eliminated once the imprinting process is completed, giving room and suitable func...

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

“…Efforts to employ MIPs in assays have extended well beyond the large volume of literature focused upon MIPSE, most notably CE and CEC, and LC . In contrast to the 1990s and early 2000s, the proportion of studies devoted to, or heavily dependent upon, LC has reduced significantly.…”

The effect of RAFT polymerization on the physical properties of thiamphenicol-imprinted polymer

“…Furthermore, the template molecule (thiamphenicol) is a small molecule (< 1 nm) and aperture of pore is less than 4 nm in P1_MIP, it may be thought that the more effective adsorption capacity could be occured. On the other hand, the smaller size distribution could raise the selectivity and increase the imprinting factor value for the polymer [13]. For adsorption/desorption isotherms studies, it was revealed more about the MIPs porosity characteristics.…”

“…Then the mesopores continue filling by capillary condensation and once again adsorption levels off as the mesopores are filled. During desorption, as pressure is lowered, the mesopores are emptied by capillary evaporation, but when capillary condensation and capillary evaporation do not take place at the same pressure, a hysteresis loop is created [13,15]. However, hysteresis loop obtained was much steeper for P2_NIP compared to P1_MIP.…”