Preparation And Characteristic Of Bovine Serum Albumin Molecularly Imprinted Polymer On The Surface Of Carbon Nanotubes By Sol-Gel Method

The concept of molecular imprinting technology (MIT) was put forward as a supporting technology for the preparation of the molecularly imprinted polymers in1940s. After being ignored for several decades, MIT has become popular for its successful use in many areas such as antibody and separation.Surface molecular imprinting is a newly developed MIT after the traditional embedding method. As compared to the embedding method, surface molecular imprinting possesses some particular advantages:has lower steric hindrance; not need to be grinded that could ensure integrity of the imprinting cavities; can improve the mechanical strength of the MIPs because of the addition of the supporter with strong mechanical properties. Studies have showed that surface molecular imprinting is a good alternative for protein imprinting. Carbon nanotubes (CNTs) are specific nanometer materials, which have been successfully used as separation materials in chromatography and extraction. Besides, CNTs possess performances of huge surface area, strong rigidity, easy modification, which indicate that CNTs have strong potentials for being used as substrate materials of MIPs.Functional monomers would to some extent determine the properties of MIPs. Room temperature ionic liquids (RTILs) were liquids totally consist of anion and cation under or around room temperature. ILs have drawn wide attention by chemists because of their properties such as negligible vapor pressure, environmental friendness, wide thermal range, high stability and designable character. Studies have verified that ILs have potentials to be used as functional monomers in preparation of protein molecularly imprinted polymers.In this work, bovine serum albumin (BSA) was used as template, TEOS was used as crosslinker, and two kinds of ILs ([TESPmim]BF4and [TESPmim]Cl) and KH-550were used as functional monomers respectively to prepare three kinds of BSA-MIPs on the surface of CNTs-KH550. The properties of the synthetic BSA MIPs, such as the thermal stability, surface morphology, imprinting effect, selectivity and reusability were characterized and evaluated comprehensively. The main results are as follows: 1. Reaction time, pH of the reaction system, content of crosslinker (the volume ratio of PBS and TEOS, R), mass ratio of template and functional monomer (M) and content of the substrate (m) were optimized for the preparation of the MIPs using [TESPmim]BF4as functional monomers. The optimal conditions were as follows:pH was7, R was5, M was60/120and content of supporter was20mg.2. Elution of BSA from the MIPs was studied. Quantitative FT-IR spectrums of the MIPs with elution times ranging from1to8were gained. The result showed that BSA was almost eluted from the MIPs after being washed for8times.3. Thermal stability:The results showed that the weight loss were20%,18%,22%and19%,24%,17%for the MIPs and NIPs synthesized with [TESPmim]BF4,[TESPmim]Cl and KH-550as functional monomers, respectively. It was mainly attributed to the loss of water and some unreacted reactants. This result indicated good thermal stability of the synthetic MIPs.4. Surface morphology:From the SEM images we can see that the MIPs were uniformly coated on the surface of CNTs-KH550and the thickness of the polymer film increased with the polymerization time. This manifested that polymerization was occurred on the surface of CNTs-KH550instead of self-polymerization in the solvent.5. Imprinting effect: Langmuir fittings of the adsorption isotherms showed that the MIPs synthesized using [TESPmim]BF4and [TESPmim]Cl as functional monomers had lower maximum adsorption capacity for BSA than that synthesized using KH-550as monomers, while the imprinting effect of the [TESPmim]BF4mediated MIPs were best. The maximum adsorption capacities were90.98mg/g,62.55mg/g and110.50mg/g, and the imprinting factors were1.43,1.29and1.34, respectively.6. Selectivity: As compared to some other proteins that are similar to BSA in size and molecular weight, the three synthetic MIPs showed higher imprinting factors for BSA. The selective factors were larger than1.0for all these proteins, which indicated the special selectivity of the synthetic MIPs for BSA due to the formation of particular imprinting holes matching to BSA during the synthesis of the MIPs.7. Reusability: Adsorption capacity of the three MIPs decreased to some extent after several adsorption-desorption-readsorption processes. After four times usage, the adsorption capacity decreased to68%,64%,55%of that of the first usage for the MIPs synthesized with [TESPmim]BF4,[TESPmim]Cl and KH-550as monomers, respectively. The reusability of these MIPs was not so good due to the insufficient elution of BSA from the MIPs after each use.The results showed that the MIPs synthesized with [TESPmim]BF4and [TESPmim]Cl as monomers had comparable or even better imprinting effect and selective adsorption ability for BSA than that synthesized with KH-550, which illustrated the potential of ILs as functional monomers in the preparation of MIPs. Preferable imprinting effect and specificity needs to be promoted in the further study, though.