State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, and Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University, Changsha 410082, China.
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, and Collaborative Innovation Center for Chemistry and Molecular Medicine, Hunan University, Changsha 410082, China.
Biosens Bioelectron. 2014 Dec 15;62:151-7. doi: 10.1016/j.bios.2014.05.072. Epub 2014 Jun 11.
In traditional electrochemical sensors, the electrochemical signal transduction of the redox-active material is usually controlled by the analytical target. Due to non-specific interaction between the redox mediator and the target, false signal by single stimulus may not be avoided. To address this issue, we have developed a new electrochemical sensor that uses a functional spiropyran, an important class of photo and thermochromic compounds, as both recognition receptor and latent redox mediator, to realize simultaneous photochemical and target-modulated electron transfer. As a proof of principle, β-galactosidase was chosen as a model target. The new synthesized spiropyran probe, SP-β-gal, undergoes reversibly structural isomerization to form merocyanine under UV light irradiation. After the glycosidic bond being cleaved by β-galactosidase, the opened merocyanine of SP-β-gal forms redox-active 2-(2.5-dihydroxystyryl)-1.3.3-trimethyl-3H-indolium, and thus produces a pair of reversible redox current peaks under the electrochemical scanning. To amplify the detection signal, SP-β-gal was self-assembled with single-walled carbon nanotubes (SWCNTs) on the surface of glass carbon electrode. Kinetics experiments confirm that the probe is an ideal candidate for the determination of different concentrations of β-galactosidase digestion kinetics. Further, the SP-β-gal/SWCNTs-modified electrode is chemically stable in complex biological fluids. It was successfully applied to monitor β-galactosidase activity in the 10% calf thymus. This work represents not only a significant step forward in the further development of low-dimensional carbon nanomaterials/small organic molecular probes-based electrochemical biosensors, but also a new platform which may be extended to the assay of other enzyme such as β-D-glycosidase and so on by translating the biorecognition into electrochemical signal responses.
在传统的电化学传感器中，氧化还原活性物质的电化学信号转导通常由分析目标控制。由于氧化还原介质与目标之间的非特异性相互作用，单一刺激可能无法避免虚假信号。为了解决这个问题，我们开发了一种新的电化学传感器，该传感器使用功能化的螺吡喃作为识别受体和潜在的氧化还原介质，同时实现光化学和目标调制的电子转移。作为原理的证明，选择β-半乳糖苷酶作为模型目标。新合成的螺吡喃探针 SP-β-gal 在紫外光照射下可逆地异构化为形成菁。在糖苷键被β-半乳糖苷酶裂解后，SP-β-gal 的开环菁形成氧化还原活性 2-(2.5-二羟基苯乙烯基)-1.3.3-三甲基-3H-吲哚，从而在电化学扫描下产生一对可逆的氧化还原电流峰。为了放大检测信号，SP-β-gal 与单壁碳纳米管 (SWCNTs) 在玻碳电极表面自组装。动力学实验证实，该探针是测定不同浓度β-半乳糖苷酶消化动力学的理想候选物。此外，SP-β-gal/SWCNTs 修饰电极在复杂的生物流体中具有化学稳定性。它成功地应用于监测小牛胸腺中的β-半乳糖苷酶活性。这项工作不仅代表了在进一步开发基于低维碳纳米材料/小分子探针的电化学生物传感器方面迈出了重要的一步，而且还提供了一个新的平台，通过将生物识别转化为电化学信号响应，可以扩展到测定其他酶，如β-D-糖苷酶等。
