title: Integrated optical microfluidic biosensor using a polycarbazole photodetector for point-of-care detection of hormonal compounds.
abstract: A picogram-sensitive optical microfluidic biosensor using an integrated polycarbazole photodiode is developed. The photodetector is mainly composed of the blend heterojunction of poly [N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl C71-butyric acid methyl ester (PC70BM) and the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as the hole transport layer. Analyte detection is accomplished via a chemiluminescent immunoassay performed in a poly(dimethylsiloxane)-gold-glass hybrid microchip, on which antibodies were immobilized and chemiluminescent horseradish peroxidase-luminol-peroxide reactions were generated. Enhanced sensor response to the chemiluminescent light is achieved by optimizing the thickness of PCDTBT:  PC70BM and PEDOT:PSS. Using the optimized polycarbazole photodiode for detecting the human thyroid-stimulating hormone as the model target, the integrated biosensor demonstrates an excellent linearity in the range of 0.03 to 10  ng/ml with an analytical sensitivity of 68  pg/ml. The sensor response shows high specificity and reproducibility. Hormone detection in clinical samples is further demonstrated and compared with a commercial enzyme-linked immunosorbent assay. The integrated device reported here has potential to detect other hormonal compounds or protein targets. Moreover, the presented concept enables the development of miniaturized, low-cost but highly sensitive optical microfluidic biosensors based on integrated polymer photodetectors with high potential for point-of-care diagnostics.
authors.forename: Nuno Miguel Matos
authors.initials: NM
authors.lastname: Pires
authors.forename: Tao
authors.initials: T
authors.lastname: Dong
authors.forename: Ulrik
authors.initials: U
authors.lastname: Hanke
authors.forename: Nils
authors.initials: N
authors.lastname: Hoivik
mesh_terms: D000328:Adult; D055910:Antibodies, Immobilized / Q000737:chemistry / Q000378:metabolism; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D006728:Hormones / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008956:Models, Chemical; D019095:Point-of-Care Systems; D011108:Polymers / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013972:Thyrotropin / Q000032:analysis
chemical_list: D055910:Antibodies, Immobilized; D006728:Hormones; D011108:Polymers; D013972:Thyrotropin