环糊精基阻抗型传感器的制备及对L-半胱氨酸的识别

借助量子化学计算,从分子层面模拟了γ-环糊精(γ-CD)主体与L-半胱氨酸(L-Cys)氧化产物客体之间的超分子相互作用,得到γ-CD与L-Cys氧化产物之间的弱相互作用能EL(-12. 6 e V),其与D-Cys氧化产物客体的弱相互作用能(E_D=-2. 7 e V)相差3. 7倍,分子内氢键键价相差近1倍.据此,构建了基于手性源γ-环糊精的阻抗型传感器,并用于L-Cys的阻抗识别.结果表明,以铁氰化钾(Ⅱ/Ⅲ)作为氧化还原探针分子,电化学阻抗信号变量(R_et)与L-Cys浓度在0. 1～1. 0μmol/L(阶段一)和1. 0～6. 0μmol/L(阶段二) 2个范围内分别呈现良好的线性关系,检出限为74 nmol/L(S/N=3).与未修饰玻碳电极相比,L-Cys在该手性传感器上的阻抗响应灵敏度提高了约19倍,对含巯基结构相似物的选择性明显提高;将该传感器应用于人体血清、药品胶囊样品的分析,平均回收率在88. 9%～108%之间.建立了一种新颖、低成本、简便的针对弱电活性手性化合物的定量识别方法,为其电化学分析提供了新策略.

Construction of Cyclodextrin-based Impedance Sensor for Recognition of L-Cysteine

By means of quantum chemical calculation,the supramolecular interaction between theγ-cyclodextrin(γ-CD)as the host and the L-cysteine(L-Cys)oxidation product as the guest was simulated from the{molecular}level.The weak interaction energy(EL)betweenγ-CD and L-Cys oxidation product reaches-12.6 eV,which is 3.7 times different from the interaction betweenγ-CD and D-Cys oxidation product(ED=-2.7 eV).Their intramolecular hydrogen bonds exist nearly doubled difference.Based on the theoretical simulation,an{γ-CD}modified impedance sensor was constructed for sensitive and specific impedance identification of{L-Cys.}Using potassium ferricyanide(Ⅱ/Ⅲ)as the redox probe,the electrochemical transfer impedance(Ret)linearly changed with the concentration of L-Cys between 0.1μmol/L and 1.0μmol/L(stage one),and from 1.0μmol/L and 6.0μmol/L(stage two),with the detection limit of 74 nmol/L(S/N=3).Compared with the unmodified glassy carbon electrode,the sensitivity for the impedance response of L-Cys has been increased about 19 times.Meanwhile,the selectivity to the thiol-containing structural analog is significantly improved by this cyclodextrin-based sensor,successfully applied for the detection in human serum and drug capsules with average recoveries between 88.9%and 108%.This study establishes a novel,low-cost,simple,quantitative{identification}method for chiral compounds with weak electrical property,providing a potential strategy for electrochemical analysis of chiral targets.