J. Non-Crystalline Sol., 354, 2594-2597 (2008)

Detection of molecular tags with an integrated amorphous silicon photodetector for biological applications

Conde, J. P., Pimentel, A. C., Pereira, A. T., Gouvêa, A., Prazeres, D. M. F., Chu, V.

Abstract

A hydrogenated amorphous silicon micro-photodiode is used to optically detect the presence, in solution, of 
species which can be used as molecular labels for biomolecules. These molecular labels are a fluorescent molecule 
and an enzyme. The light emitted by the fluorophore (Alexa Fluor 430) in solution is detected by the photodiode 
through an amorphous silicon carbon filter which absorbs the excitation light. The enzyme (horseradish 
peroxidase) is used with two different substrates (luminol and tetramethylbenzidine) to produce chemiluminescent 
and light absorbent products, respectively. Sensitivities down to picomolar level (corresponding to 1 attomole of 
molecular labels in solution) have been obtained.

Keywords: amorphous silicon micro-photodiode; Alexa Fluor, HRP

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