利用溶膠-凝膠法製備高辨識能力的17β-estradiol分子拓印材料

Abstract

17β-estradiol(E2)是內分泌干擾物中含苯環的類固醇荷爾蒙，對於野生動物及人類會造成內分泌系統干擾的負面影響，因此，針對E2發展高效能偵測方法引起廣大興趣，分子拓印高分子對於目標分子具有高選擇性和親和性，是最新發展出篩選與濃縮標的物的重要材料，本研究目的為利用溶膠-凝膠法(sol-gel)製備和鑑定17β-estradiol(E2)的分子拓印有機無機混合材料，並藉由材料與吸附能力分析了解分子拓印與最佳化製備條件。官能性單體苯基三甲氧基矽氧烷(PTMOS)和 3-氨基丙基三甲基矽氧烷(APTES)是用來當作官能性單體並分別藉由π-π作用力和氫鍵作用來和E2產生鍵結。此外，四乙烷基矽烷(TEOS)當作交聯劑並建構多孔隙凝膠，甲基三甲氧基矽烷(MTMOS)的添加可以增加材料的柔韌性。當TEOS/PTMOS/APTES/MTMOS/E2莫爾比為20:2:2:2:1時，材料於乙腈中對E2的吸附量為0.36 mg E2/g MIPs而拓印因數為1.8，其中，PTMOS和APTES分別決定材料的辨識力和吸附能量，當pH=3和水/Si莫爾比值為=3.3時，材料在乙腈中呈現最高吸附能力0.44 mg E2/g MIPs和拓印因數1.9，此外，分子拓印材料於甲苯溶劑中的吸附能力更提高至28.2 mg E2/g MIPs。分子拓印材料在經過模板萃取之後，比表面積很明顯地從288 m2/g提高到658 m2/g，孔體積也從0.25 cm3/g提高到0.59 cm3/g，另外，分子拓印材料的吸附平衡時間為4小時。分子拓印材料對於1-萘酚(1-naphthol)的選擇性(selectivity factor)為3.1而壬基苯酚(nonylphenol)的選擇性為2.3，這些結果證明拓印作用確實藉由溶膠-凝膠法產生在有機無機混合材料上。

17β-estradiol (E2) is a phenolic steroid hormone of endocrine disrupted contaminants. It has adverse effects and cause abnormality on the endocrine system of wildlife and humans. The high selectivity and affinity of molecularly imprinted polymers (MIPs) toward target molecules make them receive much attention on separation and sensing of E2. The aim of this study was to develop and characterize E2 imprinted organic-inorganic hybrid silica using a sol-gel process. Phenyltrimethoxysilane (PTMOS) and 3-aminopropyltriethoxysilane (APTES) were used as functional monomers to selectively bind E2 via π-π stacking interactions and hydrogen bonding, respectively. In addition, tetraethoxylsilane (TEOS) was used as a cross-linker to polymerize the highly porous gels. To enhance the mechanical elasticity, methyltrimethoxysilane (MTMOS) was incorporated into the gels. The recipes and sol-gel parameters were optimized to reach the highest imprinted capabilities. The imprinted material with the optimal TEOS/PTMOS/APTES/MTMOS/E2 molar ratio of 20/2/2/2/1 exhibited an adsorption capacity of 0.36 mg/g and an imprinted factor of 1.8 in acetonitrile. The PTMOS and APTES dominated the recognitions and binding quantities, respectively. The imprinted material showed the highest adsorption capacity of 0.44 mg/g and the imprinted factor of 1.9 in acetonitrile when the sol-gel process was proceeded at water/Si=3.3 and pH=3. Moreover, the adsorption capacity was remarkably enhanced to 28.2 mg/g in toluene. After removal of E2, the specific surface areas and pore volume of imprinted silica was increased significantly from 288 m2/g to 658 m2/g and 0.25 cm3/g to 0.59 cm3/g, respectively. In addition, the adsorption equilibrium time was 4 hr for the imprinted polymers. The imprinted silica performed high selectivity factor of 3.1 for 1-naphthol and 2.3 for nonylphenol in competitive adsorption systems. These results clearly demonstrated that the imprinted effect was successfully conducted in the organic-inorganic silica hybrids through the sol-gel process.