组成图示
示意图生成中
传感器类型
比色生物传感器
检测对象
敌敌畏（dichlorvos）；样品基质：水样（加标水样）
检测原理
该传感器基于酶抑制与pH光学转导。上层溶胶-凝胶膜中的AChE催化AChCl水解生成胆碱和乙酸，使局部pH下降；下层溶胶-凝胶膜中的亲脂性色离子载体ETH5294（CM）随质子化程度改变而在660 nm处吸光度发生变化，从而将pH变化转换为光学信号。敌敌畏作为有机磷杀虫剂可抑制AChE活性，使相同AChCl浓度下产酸减少、吸光度变化降低。通过比较无抑制与有抑制时的吸光度变化计算抑制率，抑制率随敌敌畏浓度增加而增大。该设计利用CM的亲脂性和溶胶-凝胶基质减少泄漏，无需共价修饰，无额外信号放大。
检测灵敏度
LOD: 0.5 mg/L；线性范围: 0.5–7 mg/L（17–85%抑制）；灵敏度斜率: 10.1%抑制/（mg/L）；R^2 = 0.991（摘要，n=9）/0.992（结果，n=9）
效应效果
该传感器无需共价固定，CM在Tris–HCl缓冲液中数小时无泄漏。对AChCl的重复性RSD为15%（n=3），对敌敌畏的RSD<16%（n=3）。响应时间约12 min，最佳孵育时间15 min。在1–10 mg/L敌敌畏范围内抑制率为25–98%，高于文献报道的10–85%。对1.7–6.0 mg/L加标水样，光学传感器与GC-MSD结果相关系数接近0.97、斜率接近1。作者称LOD 0.5 mg/L比AOAC方法高约30倍，但仍满足马来西亚食品法<2 mg/L限值，可用于杀虫剂筛查，但选择性受其他AChE抑制剂影响。
传感器的构成
- 基底：醋酸纤维素膜（cellulose acetate film），支撑两层溶胶-凝胶膜并用于光学测量
- 信号标记层：TEOS溶胶-凝胶膜（sol–gel film）掺杂亲脂性色离子载体ETH5294（CM），作为pH敏感光学指示剂并在660 nm产生吸光度变化
- 识别元件层：TEOS溶胶-凝胶膜固定乙酰胆碱酯酶（AChE），催化AChCl水解并作为敌敌畏抑制靶标
中文摘要
本文报道了一种用于检测有机磷杀虫剂敌敌畏（dichlorvos）的光学生物传感器。该传感器由两层溶胶-凝胶膜叠层构成：下层为掺杂亲脂性色离子载体ETH5294（CM）的溶胶-凝胶膜，上层为固定乙酰胆碱酯酶（AChE）的溶胶-凝胶膜。CM层对pH敏感，可光学检测AChE水解底物乙酰胆碱氯化物（AChCl）产生的pH变化。由于CM具有强亲脂性且与溶胶-凝胶基质相容，无需共价修饰即可避免泄漏。无AChE层时，CM层在pH 6–8范围内呈线性响应（R2=0.98，n=3）；加入AChE层后，传感器对AChCl在40–90 mM范围内线性响应（R2=0.984，n=6），响应时间约12 min。以15 min孵育时间建立敌敌畏抑制曲线，0.5–7 mg/L范围内线性（17–85%抑制，R2=0.991，n=9），检出限为0.5 mg/L。对1.7–6.0 mg/L加标水样的检测结果与GC-MS法一致。
英文摘要
An optical biosensor consisting of a chromoionophore (ETH5294) (CM) doped sol-gel film interfaced with another sol-gel film immobilized with acetylcholinesterase (AChE) was employed to detect the insecticide dichlorvos. The main advantage of this optical biosensor is the use of a sol-gel layer with immobilized CM that possesses lipophilic property. The highly lipophilic nature of the CM and its compatibility with the sol-gel matrix has prevented leaching, which is frequently a problem in optical sensor construction based on pH indicator dyes. The immobilization of the indicator and enzyme was simple and need no chemical modification. The CM layer is pH sensitive and detects the pH changes of the acetylcholine chloride (AChCl) substrate when hydrolyzed by AChE layer deposited above. In the absence of the AChE layer, the pH response of the CM layer is linear from pH 6 to 8 (R(2)=0.98, n=3) and it showed no leaching of the lipophilic chromoionophore. When the AChE layer is deposited on top, the optical biosensor responds to AChCl with a linear dynamic range of 40-90mM AChCl (R(2)=0.984, n=6). The response time of the biosensor is 12min. Based on the optimum incubation time of 15min, a linear calibration curve of dichlorvos against the percentage inhibition of AChE was obtained from 0.5 to 7mg/L of dichlorvos (17-85% inhibition, R(2)=0.991, n=9). The detection limit for dichlorvos was 0.5mg/L. The results of the analysis of 1.7-6.0mg/L of dichlorvos using this optical biosensor agreed well with a gas chromatography-mass spectrometry detection method.