Abstract
In this study, an optical biosensor for human serum albumin (HSA) detection was demonstrated utilizing a simple and small volume optical system. For the fabrication process of the optical biosensor, the glass sensing surface was modified by 3-aminopropyltriethoxysilane (APTES) or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) / N-Hydroxysuccinimide (NHS) to improve the biocompatibility. Following that, the sensing surface was modified with anti-human serum albumin (AHSA), blocked by bovine serum albumin (BSA), conjugated with targeted HSA, and finally bonded with AHSA-modified quantum dots (emission wavelength : 655 nm) for HSA detection after N2 drying. The photocurrent contributed by various concentrations of HSA was measured and quantified by semiconductor parameter analyzer under DC condition in this work. Results showed that the photocurrent increased linearly as the HSA conjugation increased from 2x10-4 mg/ml to 2x10-1 mg/ml, with a detection limit of 3.2□10-5 mg/ml. In summary, this study has successfully demonstrated the feasibility of utilizing optical mechanism (by measuring the photocurrent change of photodetector induced by fluorescence intensity change before and after HSA, and QDs conjugating) to quantify human serum albumin (HSA) concentration. Compared to the traditional fluorescence biosensors, both diode laser light source and photodetector were low-cost and small-volume electronics in this work. This portable, simple optical system consisted of lens, filter, diode laser, and photodetector, exhibiting advantages of ease to be integrated with biochips, timely output, and low cost, that can be used for future protein detection.