title: Paper-based electroanalytical devices for in situ determination of salicylic acid in living tomato leaves.
abstract: Detection of phytohormones in situ has gained significant attention due to their critical roles in regulating developmental processes and signaling for defenses in plants at low concentration. As one type of plant hormones, salicylic acid has recently been found to be one of pivotal signal molecules for physiological behaviors of plants. Here we report the application of paper-based electroanalytical devices for sensitively in situ detection of salicylic acid in tomato leaves with the sample volume of several microliters. Specifically, disposable working electrodes were fabricated by coating carbon tape with the mixture of multiwall carbon nanotubes and nafion. We observed that the treatment of the modified carbon tape electrodes with oxygen plasma could significantly improve electrochemical responses of salicylic acid. The tomato leaves had a punched hole of 1.5mm diameter to release salicylic acid with minor influence on continuous growth of tomatoes. By incorporating the tomato leaf with the paper-based analytical device, we were able to perform in situ determination of salicylic acid based on its electrocatalytic oxidation. Our experimental results demonstrated that the amounts of salicylic acid differed statistically in normal, phytoene desaturase (PDS) gene silent and diseased (infected by Botrytis cinerea) tomato leaves. By quantifying salicylic acid at the level of several nanograms in situ, the simple paper-based electroanalytical devices could potentially facilitate the study of defense mechanism of plants under biotic and abiotic stresses. This study might also provide a sensitive method with spatiotemporal resolution for mapping of chemicals released from living organisms.
authors.affiliation: Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, 9 Seyuan Rd., Nantong, Jiangsu 226019, People's Republic of China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Sun
authors.affiliation: Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, 9 Seyuan Rd., Nantong, Jiangsu 226019, People's Republic of China.
authors.forename: Qiu-Mei
authors.initials: QM
authors.lastname: Feng
authors.affiliation: Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, 9 Seyuan Rd., Nantong, Jiangsu 226019, People's Republic of China.
authors.forename: Yong-Feng
authors.initials: YF
authors.lastname: Yan
authors.affiliation: Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, 9 Seyuan Rd., Nantong, Jiangsu 226019, People's Republic of China.
authors.forename: Zhong-Qin
authors.initials: ZQ
authors.lastname: Pan
authors.affiliation: National Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, Zhejiang 310058, People's Republic of China.
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Li
authors.affiliation: National Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University, 866 Yuhangtang Rd., Hangzhou, Zhejiang 310058, People's Republic of China.
authors.forename: Feng-Ming
authors.initials: FM
authors.lastname: Song
authors.affiliation: Department of Horticulture, Purdue University, 625 Agriculture Mall Drive, West Lafayette, IN 47907-2010, USA.
authors.forename: Haibing
authors.initials: H
authors.lastname: Yang
authors.affiliation: School of Chemistry and Chemical Engineering, Nanjing University, 22 Hankou Rd., Nanjing, Jiangsu 210093, People's Republic of China.
authors.forename: Jing-Juan
authors.initials: JJ
authors.lastname: Xu
authors.affiliation: Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, 9 Seyuan Rd., Nantong, Jiangsu 226019, People's Republic of China. Electronic address: ningbao@ntu.edu.cn.
authors.forename: Ning
authors.initials: N
authors.lastname: Bao
authors.affiliation: Institute of Analytical Chemistry for Life Science, School of Public Health, Nantong University, 9 Seyuan Rd., Nantong, Jiangsu 226019, People's Republic of China. Electronic address: hygu@ntu.edu.cn.
authors.forename: Hai-Ying
authors.initials: HY
authors.lastname: Gu
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D018551:Solanum lycopersicum / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry; D010209:Paper; D010937:Plant Growth Regulators / Q000032:analysis*; D018515:Plant Leaves / Q000737:chemistry*; D015203:Reproducibility of Results; D020156:Salicylic Acid / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity
chemical_list: D037742:Nanotubes, Carbon; D010937:Plant Growth Regulators; D020156:Salicylic Acid
keywords: Modified electrodes; Paper-based analytical devices; Phytohormones; Salicylic acid; in situ electrochemical detection