title: Nanoplasmonic biochips for rapid label-free detection of imidacloprid pesticides with a smartphone.
abstract: The widespread and intensive use of neonicotinoid insecticides induces negative cascading effects on ecosystems. It is desirable to develop a portable sensitive sensing platform for on-site screening of high-risk pesticides. We combined an indirect competitive immunoassay, highly sensitive surface plasmon resonance (SPR) biochip and a simple portable imaging setup for label-free detection of imidacloprid pesticides. The SPR biochip consists of several capped nanoslit arrays with different periods which form a spectral image on the chip. The qualitative and semiquantitative analyses of pesticides can be directly observed from the spot shift on the chip. The precise semiquantitative analyses can be further completed by using image processing in a smartphone. We demonstrate simultaneous detection of four different concentrations of imidacloprid pesticides. The visual detection limit is about 1ppb, which is well below the maximum residue concentration permitted by law (20ppb). Compared to the one-step strip assay, the proposed chip is capable of performing semiquantitative analyses and multiple detection. Compared to the enzyme-linked immunosorbent assay, our method is label-free and requires simple washing steps and short reaction time. In addition, the label-free chip has a comparable sensitivity but wider working range than those labeling techniques.
authors: Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors: Kuang-Li
authors: KL
authors: Lee
authors: Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan.
authors: Meng-Lin
authors: ML
authors: You
authors: Department of Entomology, National Taiwan University, Taipei 10617, Taiwan.
authors: Chia-Hsin
authors: CH
authors: Tsai
authors: Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors: En-Hung
authors: EH
authors: Lin
authors: Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors: Shu-Yi
authors: SY
authors: Hsieh
authors: Agricultural Chemicals And Toxic Substances Research Institute, Taichung 41358, Taiwan.
authors: Ming-Hsun
authors: MH
authors: Ho
authors: Department of Entomology, National Taiwan University, Taipei 10617, Taiwan. Electronic address: juchun@ntu.edu.tw.
authors: Ju-Chun
authors: JC
authors: Hsu
authors: Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan; Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan; Department of Optoelectronics, National Taiwan Ocean University, Keelung 20224, Taiwan. Electronic address: pkwei@sinica.edu.tw.
authors: Pei-Kuen
authors: PK
authors: Wei
mesh_terms: D015374:Biosensing Techniques; D006801:Humans; D007093:Imidazoles / Q000302:isolation & purification* / Q000633:toxicity; D056656:Lab-On-A-Chip Devices; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000302:isolation & purification* / Q000633:toxicity; D010575:Pesticides / Q000302:isolation & purification* / Q000633:toxicity; D000068997:Smartphone; D020349:Surface Plasmon Resonance
chemical_list: D007093:Imidazoles; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010575:Pesticides; C082359:imidacloprid
keywords: Imidacloprid insecticide; Label-free detection; Nanostructure; Optical biosensor; Spectral image; Surface plasmon resonance