Thin Film Nano Technology Laboratory, Department of Electronic Engineering, Chang Gung University, Tao-Yuan, Taiwan 333, Taiwan.
Nanoscale Res Lett. 2014 Apr 12;9(1):179. doi: 10.1186/1556-276X-9-179.
Time-dependent pH sensing phenomena of the core-shell CdSe/ZnS quantum dot (QD) sensors in EIS (electrolyte insulator semiconductor) structure have been investigated for the first time. The quantum dots are immobilized by chaperonin GroEL protein, which are observed by both atomic force microscope and scanning electron microscope. The diameter of one QD is approximately 6.5 nm. The QDs are not oxidized over a long time and core-shell CdSe/ZnS are confirmed by X-ray photon spectroscopy. The sensors are studied for sensing of hydrogen ions concentration in different buffer solutions at broad pH range of 2 to 12. The QD sensors show improved sensitivity (38 to 55 mV/pH) as compared to bare SiO2 sensor (36 to 23 mV/pH) with time period of 0 to 24 months, owing to the reduction of defects in the QDs. Therefore, the differential sensitivity of the QD sensors with respect to the bare SiO2 sensors is improved from 2 to 32 mV/pH for the time period of 0 to 24 months. After 24 months, the sensitivity of the QD sensors is close to ideal Nernstian response with good linearity of 99.96%. Stability and repeatability of the QD sensors show low drift (10 mV for 10 cycles) as well as small hysteresis characteristics (<10 mV). This QD sensor is very useful for future human disease diagnostics.
首次研究了核壳型 CdSe/ZnS 量子点（QD）传感器在 EIS（电解质-绝缘体-半导体）结构中的时间依赖 pH 传感现象。量子点通过伴侣蛋白 GroEL 固定，并用原子力显微镜和扫描电子显微镜进行观察。一个 QD 的直径约为 6.5nm。量子点在很长时间内不会被氧化，并且通过 X 射线光电子能谱证实了核壳型 CdSe/ZnS 的存在。在 2 至 12 的宽 pH 范围内，对不同缓冲溶液中的氢离子浓度进行了传感器传感研究。与裸 SiO2 传感器（36 至 23 mV/pH）相比，QD 传感器的灵敏度（38 至 55 mV/pH）有所提高，这是由于 QD 中的缺陷减少。因此，在 0 至 24 个月的时间内，QD 传感器相对于裸 SiO2 传感器的差分灵敏度提高了 2 至 32 mV/pH。24 个月后，QD 传感器的灵敏度接近理想的能斯特响应，线性度为 99.96%。QD 传感器的稳定性和重复性表现出低漂移（10 个循环 10mV）和小滞后特性（<10mV）。这种 QD 传感器非常有助于未来的人类疾病诊断。
