Li Fang, Zhang Jizhao, Hu Shihui, Jia Yunfang
College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071, China.
ACS Sens. 2021 Mar 26;6(3):1218-1227. doi: 10.1021/acssensors.0c02515. Epub 2021 Feb 5.
A light addressable potentiometric sensor (LAPS) is a versatile sensing platform for bioassay. However, the lack of carbon-based LAPS (C-LAPS) is a bottleneck for its sustainable development in a carbon electronic era. Herein, a study of C-LAPS based on the combinations of carbon dots (CDs) and liquid exfoliated graphene (LEG) is presented. Devices of C-LAPS are first fabricated by self-assembling the hydrothermally synthesized CDs and the cosolvent ultrasonic delaminated LEG on poly(diallyldimethylammonium chloride) (PDDA)-modified indium tin oxide (ITO) glasses. According to the stacking orders of CDs and LEG, C-LAPS are named as CDs/LEG@PDDA/ITO and LEG/CDs@PDDA/ITO. Then, their electronic and photoelectronic features are measured and compared with the pure CD- and pure LEG-decorated ITO electrodes. Furthermore, working mechanisms are proposed by means of the classical theories of energy band bending and built-in electric field at the heterojunction of CDs and LEG. The resemblances of CDs/LEG@PDDA/ITO-based C-LAPS with Si-based LAPS (Si-LAPS) are confirmed from the points of view of production and separation of the photogenerated carriers, the formation of photocurrent, and the distinction with LEG/CDs@PDDA/ITO. Finally, its feasibility for biological application is justified by using the immune reaction of 5-methylcytosine (5mC) and its antibody (anti-5mC) as a proof of concept. The improved linear responses are evidenced by the comparisons with Si-LAPS' results. Conclusively, the proposed C-LAPS is believed to be a candidate for traditional semiconductor-based LAPS, with the merit of solution-processable. Meanwhile, the theoretical deductions about C-LAPS' principle can also pave the way for developing similar carbon-based sensors.
光寻址电位传感器（LAPS）是一种用于生物检测的多功能传感平台。然而，缺乏基于碳的LAPS（C-LAPS）是其在碳电子时代可持续发展的瓶颈。在此，本文介绍了一项基于碳点（CDs）和液相剥离石墨烯（LEG）组合的C-LAPS研究。首先，通过将水热合成的CDs和共溶剂超声剥离的LEG自组装在聚二烯丙基二甲基氯化铵（PDDA）修饰的氧化铟锡（ITO）玻璃上，制备了C-LAPS器件。根据CDs和LEG的堆叠顺序，C-LAPS被命名为CDs/LEG@PDDA/ITO和LEG/CDs@PDDA/ITO。然后，测量了它们的电子和光电子特性，并与纯CD修饰和纯LEG修饰的ITO电极进行了比较。此外，通过能带弯曲和CDs与LEG异质结处内建电场的经典理论提出了工作机制。从光生载流子的产生和分离、光电流的形成以及与LEG/CDs@PDDA/ITO的区别等角度，证实了基于CDs/LEG@PDDA/ITO的C-LAPS与基于硅的LAPS（Si-LAPS）的相似性。最后，以5-甲基胞嘧啶（5mC）及其抗体（抗5mC）的免疫反应作为概念验证，证明了其在生物应用中的可行性。与Si-LAPS的结果比较证明了改进的线性响应。总之，所提出的C-LAPS被认为是传统半导体基LAPS的候选者，具有可溶液加工的优点。同时，关于C-LAPS原理的理论推导也可为开发类似的碳基传感器铺平道路。
