Photodiode Array On-chip Biosensor for the Detection of E. coli O157:H7 Pathogenic Bacteria
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An integrated circuit (IC) of photodiode array (PDA) microchip system was used for the on-chip detection of E. coli
O157:H7 based on an enzymatic bioassay and light absorption property of the reaction product. The PDA microchip consisting
of an array of 12 � 12 photodiode detection elements served as a photosensor as well as a protein-immobilizing sample platform.
As a result, E. coli
O157:H7 could be detected directly on the surface of PDA detection elements. E. coli
O157:H7 was detected by forming a “sandwich-type” enzymatic immunocomplex on the PDA detection elements using an on-chip
bioassay. The quantitative analysis of E. coli
O157:H7 immunocomplex was carried out based on the light absorption property of the enzymatic reaction products of E. coli
O157:H7 immunocomplexes with respect to a red beam produced by light emitting diodes (LEDs) installed right above the PDA
microchip. During the on-chip bioassay, the wet photodiode detection elements exposed to a lot of biological materials or
buffer solutions were capable of maintaining their photosensing capabilities. The portable PDA on-chip biosensor permits direct
optical detection of E. coli
O157:H7 and eliminates the necessity of the conventional expensive microplate reader that is incompatible with the size of
the protein microarray.