The Preparation Of Surface Molecular Imprinted Graphene Composites And Their Applications

Surface imprinting technology, building molecular recognition systems on the supporting materials surface, enables the imprinted binding sites to locate at or approximate to the surface of supporting materials. So compared to the conventional imprinted polymers, surface molecularly imprinted polymers(SMIPs) exhibit more complete removal of templates, higher binding capacity, and faster binding kinetics. SMIPs have attracted increasing research interest with potential applications such as chromatographic separations, solid phase extraction and chemo/biosensors in the last decade. Graphene has attracted tremendous attention in preparing molecularly imprinted polymer(MIPs) as a good supporting material due to its large surface area, extraordinary electronic conductivity, specially thermal, mechanical and chemical properties. In this work, a series of graphene based surface MIPs were successfully prepared, and used for electrochemical sensors and specific recognition and separation of glycoprotein. The experiments showed that the resulting imprinted material showed good speci?c recognition behavior toward the template molecule. The detailed experiments are described as follows:A novel and convenient strategy was developed to prepare molecularly imprinted polymers(MIPs) on the surface of graphene sheet via free radical polymerization(FRP). In this route, vinyl group functionalized graphene(GR/NVC) is first prepared by immobilizing 9-vinylcarbazole(NVC) onto the surface of graphene via π-π interaction. The GR/MIPs composite was obtained with GR/NVC as supporting materials, p-nitrophenol(4-NP) as template, methacrylic acid(MAA) as functional monomer, ethylene glycol dimethacrylate(EGDMA) as cross-linking agent and azoisobutyronitrile(AIBN) as initiator. The effects of the preparation conditions, such as concentration of the NVC and template, the solution p H, and incubation time, were also optimized. The GR/MIPs composite was used to fabricate electrochemical sensor for the specific recognition and detection of 4-NP. Under optimized conditions, the DPV current response of GR/MIPs sensor was nearly 12 times that of the GR/NIPs sensor. It also should be noted that compared to traditional MIP, shorter response time and much higher current response was demonstrated. The peak current is linearly proportional to the concentration of 4-NP ranging from 0.01 μM to 100 μM and 200 μM to 1000 μM with the detection limit of 5 n M, a wider response range and lower detection limits compared to most previously reported electrochemical sensors for 4-NP. The GR/MIPs sensor could recognize 4-NP from its structurely analogs, indicating the excellent selectivity of the GR/MIPs sensor. Good stability and reproducibility have also been demonstrated. Furthermore, the GR/MIP sensor has been sucessfully used to determine 4-NP in lake water and tap water samples.A simple surface molecular imprinting route was developed to prepare a composite of graphene oxide/molecularly imprinted polymer(GO/MIPs) through one-pot room-temperature sol-gel polymerization in aqueous solution. The GO/MIP composite was obtained with GO as supporting materials, paracetamol(PR) as template, phenyltriethoxysilane(PTEOS) and tetramethoxysilane(TMOS) as monomer through a one-pot sol-gel reaction. The composite was then applied as a molecular recognition element to construct electrochemical sensor for the determination of paracetomal, and the factor for the sensor preparation, such as the monomer and template concentration, the incubation time were optimized. The GO/MIP sensor displayed an excellent recognition capacity toward PR compared with other analogues. Additionally, Under optimal experimental conditions, the DPV peak current was linearly proportional to the concentration of parcetamol in the range from to 0.1 μM to 80 μM, with a detection limit down to 0.02 μM(S/N = 3), which revealed a wider linear response and lower detection limit compared to most previously reported paracetamol electrochemical sensors. In addition, the new GO/MIP sensor also exhibited excellent stability, and has been used to determine paracetamol in tablets and human urine samples with satisfactory results.A noval kind of molecular imprinting composites(GO/APBA/MIPs) were synthesized combining the merits of surface imprinting, GO, boronate a?nity and sol–gel technology for specific recognition of ovalbumin(OVA). The effects of different conditions such as the amount of siloxane, APBA and ova, reaction time and p H value on the recognition properties of the GO/APBA/MIPs was investigated. The resulting GO/APBA/MIPs showed a larger specific surface area than GO/APBA/NIPs and its average pore size reached 19.789 nm. Due to the introducing of boronic acid, which could form reversible covalent bonds with OVA, the GO/APBA/MIPs exhibited faster rebinding kinetics(reaching saturated adsorption within 60 min), higher adsorption capacity(359.7 mg g-1) and speci?c recognition behavior toward OVA in adsorption experiment than GO/MIPs. The GO/APBA/MIPs can be used for the separation of OVA.