A Micrograting Sensor for DNA Hybridization and Antibody Human Serum Albumin–Antigen Human Serum Albumin Interaction Experiments

NAPHAT CHATHIRAT; NITHI ATTHI; CHARNDET HRUANUN; AMPORN POYAI; SUTHISA LEASEN; TANAKORN OSOTCHAN; JOSE H. HODAK

JAPANESE JOURNAL OF APPLIED PHYSICS

JAPAN SOCIETY APPLIED PHYSICS

Año: 2011 vol. 50 p. 1 - 6

0021-4922

A biosensor structure comprising silicon nitride (Si3N4) micrograting arrays coated with a spin-on-glass (SOG) material was investigated. Thisgrating structure was located on a silicon groove, which was etched by a deep reactive ion etching (DRIE) process. The biosensor was used as aspecific detector of DNA molecules and antibody–antigen interactions. In our DNA sensing experiments, the first step was the activation of thegrating surface with amine functional groups, followed by attachment of a 23-base oligonucleotide probe layer for hybridization with acomplementary target DNA. The sensing device was tested for detecting specific antigen/antibody interactions for human serum albumin (HSA)and antigen bovine serum albumin (BSA). The readout system consisted of a white light lamp that illuminated a small spot on the grating surfaceat normal incidence through a fiber optic probe with a spectrometer used to collect the reflected light through a second fiber. We show that thesesensing devices have the capability to detect DNA as well as antigen–antibody binding for HSA. The detection sensitivity for HSA was better thanthat for DNA mainly owing to the larger size and concomitant refractive index changes upon binding to the sensor. We show that it is possible toquantify the amount of biomolecules bound to the grating surface by measuring the wavelength shift of the reflectance spectra upon exposure tothe samples.