Four detection zones (AD, chamber + OPD) were monitored using two multi-channel SMUs, and chemiluminescent immunoassays were performed following the protocol: (1) monoclonal antibody; (2) blocking buffer; (3) pathogen-spiked sample; (4) biotinylated antibody; (5) streptavidin-HRP conjugate; (6) chemiluminescent substrate. The multiplexed detection was performed by targeting heat-killedE. the use of OPDs in integrated microfluidic systems for both fluorescence and chemiluminescence detection of analytes has been reported [69]. A fluorescence detector for biomarkers and molecular probes [7,9] was constructed from heterojunction photodiodes of copper phthalocyanine (CuPc) and fullerene (C60), whilst chemiluminescence sensors [4,6] were developed using blend heterojunctions of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC60BM). However, the insufficient sensitivity and high detection limit (LOD) of the reported detection methods may limit the use of OPD-based analytical systems compared to conventional analytical chips. In the past few years there has been tremendous progress in Inulin the field of OPD technology, and new conjugated polymers and C70derivatives have been developed with the purpose of TNFRSF9 improving the power conversion efficiency of organic solar cells [10,11]. Poly[N-9-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (PCDTBT) is one of new conjugated polymers that forms a blend heterojunction with PC70BM, resulting in detectors with enhanced light absorption, higher short-circuit current density and lower dark current compared to P3HT:PC60BM blends [12]. Inulin Owing to these unique characteristics, the PCDTBT:PC70BM heterojunction photodiode may be promising for OPD-based chemical and biological sensors in applications requiring high detection sensitivities. Detection of pathogens in water, for instance, often involves analysis for low concentrations of protozoa, bacteria and viruses in the samples. Highly sensitive methods are thus required for monitoring the safety of water [1315], and the tests are preferred to be conducted at the point of care in order to obtain rapid results [16]. An ideal point-of-care device should perform multiplexed tests as both drinking water and surface water are vulnerable toEscherichia coli,Campylobacterand adenovirus, among others [17,18]. Although arrays of organic light emitting diodes have been used for multiplexed detection [19], no OPD-based multi-analyte sensor has yet been demonstrated. Multiplexed detection of pathogens can be accomplished using immunological methods [20,21]. Immunoassays are extensively employed in lab-on-a-chip devices, and rapid analyte detection is typically accomplished by use of either optical or electrochemical methods [2224]. The electrochemical method is definitely discouraged in disposable microfluidic chips as it is definitely often affected by variations of heat, pH and ionic concentrations, whilst the development of optical methods for microfluidic detectors has recently received substantial attention in Inulin on-site sensing [2]. Thus, a number of optical detectors, such as silicon photodiode arrays, ring resonators and photonic crystals have been analyzed in integrated microfluidic systems [25,26]. These integrated detectors involve complex, high-cost fabrication which limits their feasibility for point-of-use screening despite their high level of sensitivity and potential for multiplexed detection. Instead, the low-cost fabrication of OPDs may facilitate multiplexing of the integrated products and allows their mass production. This work presents a multiplexed optical-biosensor platform with highly sensitive organic photodiodes integrated to a single microfluidic chip. Detection ofE. coli,Campylobacter jejuniand adenovirus was carried out by integrated PCDTBT:Personal computer70BM blend heterojunction photodiodes. Immunoassays were performed on functionalized plastic microfluidic substrate and the luminol chemiluminescence reaction was used as the transduction mechanism. Chemiluminescence may be an ideal treatment for on-site applications comparing to additional optical readout methods [27], as it allows great reduction in the difficulty of the detection system design [28]. The optoelectronic overall performance of a single PCDTBT:Personal computer70BM sensor pixel was characterized before analysing the pathogen detection. Individual and multiplexed detection of waterborne pathogens with the OPD-integrated microfluidic platform was then shown in both artificial and actual water samples. == 2. Experimental Section == == 2.1. Integrated System Design and Fabrication == The multiplexed optical-biosensor platform is definitely depicted inFigure 1. It is primarily composed of an.