The fabrication of a photoresponsive molecularly imprinted polymer for the photoregulated uptake and release of caffeine
The fabrication of a photoresponsive molecularly imprinted polymer for the photoregulated uptake and release of caffeine
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DOI：
10.1002/adfm.200500907
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发表时间：
2006-09-05
影响因子：
19
通讯作者：
Yu, Hongxia
中科院分区：
文献类型：
--
作者：
Gong, Chengbin;Lam, Michael Hon-Wah;Yu, Hongxia
以咖啡因为模板分子，偶氮苯类功能单体4-[（4-甲基丙烯酰氧基）苯偶氮]苯甲酸（MPABA）为模板分子，成功制备了具有光响应性的分子印迹聚合物（MIP）材料。MPABA的反式光异构化性质在并入到刚性3D交联聚合物基质中后得以保留。MIP受体位点的底物亲和力是可光切换的。这可以归因于MIP受体内偶氮苯发色团的光异构化，导致其几何形状和结合功能的空间排列的改变。在二甲基亚砜中，MIP受体与咖啡因的有利结合常数为5.48 × 10（4）M-1。MIP材料中咖啡因特异性受体位点的密度为0.95 μ mol（g MIP）（-1）。在365 μ m照射后，58.3%的受体结合咖啡因从MIP材料中释放。随后在440 nm处的照射导致96.4%的释放的咖啡因被MIP材料反弹。这种释放的咖啡因的近定量摄取是偶氮苯发色团的光开关过程中受体位点构型和底物亲和力的可逆性的证据。虽然光调节底物释放和摄取过程通常是可重复的，但观察到底物释放和再结合的程度逐渐降低。这可能是由于MIP受体在重复光开关过程中缓慢变形所致。这项工作的结果表明，刺激响应MIP材料作为智能化学品和药物输送系统的潜力。
A photoresponsive molecularly imprinted polymer (MIP) material is successfully fabricated from an azobenzene-based functional monomer, 4-[(4-methacryloyloxy)phenylazo]benzoic acid (MPABA), using caffeine as a molecular template. The transcis photoisomerization properties of MPABA are retained after incorporation into the rigid 3D crosslinked polymer matrix. Substrate affinity of the MIP receptor sites is photoswitchable. This can be attributed to the photoisomerization of azobenzene chromophores within the MIP receptors, resulting in the alteration of their geometry and the spatial arrangement of their binding functionalities. The favorable binding constant of the MIP receptors for caffeine is 5.48 x 10(4) M-1 in dimethylsulfoxide. The density of the caffeine-specific receptor sites in the MIP material is 0.95 mu mol (g MIP)(-1). Upon irradiation at 365 urn, 58.3% of receptor-bound caffeine is released from the MIP material. Subsequent irradiation at 440 nm causes 96.4% of the released caffeine to be rebound by the MIP material. This near-quantitative uptake of the released caffeine is evidence of the reversibility of the receptor-site configuration and substrate affinity during the photoswitching of the azobenzene chromophores. Although the photoregulated substrate release and uptake processes are generally repeatable, a gradual reduction in the extent of substrate release and rebinding is observed. This may be caused by the slow deformation of MIP receptors during the course of repetitive photoswitching. The results of this work demonstrate the potential of stimuli-responsive MIP materials as smart chemicals and as drug-delivery systems.