An organic thin film photodiode as a portable photodetector for the detection of alkylphenol polyethoxylates by a flow fluorescence-immunoassay on magnetic microbeads in a microchannel

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• 作者：Ryoichi Ishimatsu ; Azusa Naruse ; Rong Liu ; Koji Nakano ; Masayuki Yahiro ; Chihaya Adachi ; Toshihiko Imato
• 关键词：Organic photodiodes ; Microchip ; ELISA ; Microbeads
• 刊名：Talanta
• 出版年：15 December, 2013
• 年：2013
• 卷：117
• 期：Complete
• 页码：139-145
• 全文大小：1272 K

文摘

An organic thin film photodiode (OPD) was successfully employed as a portable photodetector in a competitive enzyme-linked immunosorbent assay (ELISA) of a class of nonionic surfactants, namely alkylphenol polyethoxylates (APnEOs) which are an environmental pollutant. Microbeads that were chemically immobilized with an anti-APnEOs antibody were used in the assay. The OPD consisted of a layer of copper phthalocyanine (CuPc), C₆₀ and a second layer of bathocuproine (BCP) with a bulk heterojunction composed of CuPc and C₆₀ prepared by a vapor deposition method on an indium-tin oxide coated glass substrate. The OPD showed an incident photon-current efficiency (IPCE) of approximately 19% for light at a wavelength of 585 nm. This relatively high IPCE at 585 nm makes it suitable for detecting the fluorescence of resorufin (位_em=585 nm), the product of the competitive ELISA, produced through the enzymatic reaction of Amplex Red with horseradish peroxidase (HRP) and H₂O₂. A fluorometric detector was assembled on a microchip by combining the fabricated OPD and a commercial LED as a photodetector and a light source, respectively. The photocurrent of the OPD due to the fluorescence of resorufin was proportional to the concentration of resorufin in the concentration range from 0 to 8 渭M. When the fabricated OPD was used as a portable photodetector, the competitive ELISA of APnEOs using HRP labeled APnEOs (HRP-APnEOs) was performed on magnetic microbeads on which surface an anti-APnEOs antibody had been immobilized. A typical sigmoidal calibration curve was obtained and the data were in good agreement with a numerical simulation, where the photocurrent of the OPD was plotted against the concentration of APnEOs, determined via the competitive ELISA. The detection limit of the immunoassay for APnEOs was approximately 2 and 4 ppb in batch and flow system, respectively.