Laboratory of Nanotechnology, Department of Functional Materials and Electronics, Center for Physical Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania.
Department of Physical Chemistry, Faculty of Chemistry and Geosciences, Institute of Chemistry, Vilnius University, Naugarduko Str. 24, LT-03225 Vilnius, Lithuania.
Sensors (Basel). 2021 Dec 29;22(1):232. doi: 10.3390/s22010232.
Polypyrrole (Ppy) and poly(methylene blue) (PMB) heterostructure (Ppy-PMB) was electrochemically formed on the indium tin oxide (ITO) coated glass slides, which served as working electrodes. For electropolymerization, a solution containing pyrrole, methylene blue, and a saccharide (lactose, sucrose, or heparin) that served as dopant was used. The aim of this study was to compare the effect of the saccharides (lactose, sucrose, and heparin) on the electrochromic properties of the Ppy-PMB layer. AFM and SEM have been used for the analysis of the surface dominant features of the Ppy-PMB layers. From these images, it was concluded that the saccharides used in this study have a moderate effect on the surface morphology. Electrochromic properties were analyzed with respect to the changes of absorbance of the layer at two wavelengths (668 nm and 750 nm) by changing the pH of the surrounding solution and the potential between +0.8 V and -0.8 V. It was demonstrated that the highest absorbance changes are characteristic for all layers in the acidic media. Meanwhile, the absorbance changes of the layers were decreased in the more alkaline media. It was determined that the Ppy-PMB layers with heparin as a dopant were more mechanically stable in comparison to the layers doped with lactose and sucrose. Therefore, the Ppy-PMB layer doped with heparin was selected for the further experiment and it was applied in the design of electrochromic sensors for the determination of three xanthine derivatives: caffeine, theobromine, and theophylline. A linear relationship of Δ (∆ = - ) vs. concentration was determined for all three xanthine derivatives studied. The largest change in optical absorption was observed in the case of theophylline determination.
聚吡咯（Ppy）和聚亚甲蓝（PMB）杂化（Ppy-PMB）通过电化学在氧化铟锡（ITO）涂覆的玻璃片上形成，作为工作电极。对于电聚合，使用含有吡咯、亚甲蓝和糖（乳糖、蔗糖或肝素）作为掺杂剂的溶液。本研究的目的是比较糖（乳糖、蔗糖和肝素）对 Ppy-PMB 层电致变色性能的影响。使用 AFM 和 SEM 分析 Ppy-PMB 层的表面主要特征。从这些图像可以得出结论，本研究中使用的糖对表面形态有适度的影响。通过在 +0.8 V 和 -0.8 V 之间改变周围溶液的 pH 值和电势，分析了电致变色性能，以研究层在两个波长（668nm 和 750nm）处的吸光度变化。结果表明，所有层在酸性介质中都具有最高的吸光度变化。同时，在更碱性的介质中，层的吸光度变化减小。确定与用乳糖和蔗糖掺杂的层相比，用肝素掺杂的 Ppy-PMB 层具有更高的机械稳定性。因此，选择肝素掺杂的 Ppy-PMB 层进行进一步实验，并将其应用于设计用于测定三种黄嘌呤衍生物：咖啡因、可可碱和茶碱的电致变色传感器。确定了所有三种研究的黄嘌呤衍生物的 Δ（Δ= - ）与浓度之间的线性关系。在茶碱测定的情况下观察到最大的光学吸收变化。
