Real-time biosensing of growth hormone on porous silicon by reflectometric interference Fourier transform spectroscopy

Deficiency in human growth hormone (hGH) can have a wide range of effects throughout the body. Early detection of this deficiency improves effectiveness treatment. This study investigated the fabrication of fluidic optical nanobiosensor based on reflectometric interferometry Fourier transform spectroscopy (RIFTS) to perform real-time biosensing. Initially, single-layer porous silicon (PSi) with 20–25 nm pore diameters was fabricated in two etching steps by the electrochemical method. The fluidic device was manufactured by the CO 2 laser method. After integrating the PSi into the fluidic device, its performance was checked by two initial experiments measuring different concentrations of ethanol and lipid nanoparticles with diameters around 10–15 nm. To identify growth hormone, the PSi surface was modified by APTES ((3-Aminopropyl) triethoxysilane), glutaraldehyde (GA) as biochemical linkers, and then anti-growth hormone antibody (anti-hGH) as bioreporter. Linear responses to hGH in the range of 500 pg/ml-50 µg/ml in PBS buffer and in human serum were obtained. The detection limits for hGH in buffer and serum were measured as 0.38 and 0.30 ng/ml, respectively. Finally, the specificity of PSi nanobiosensor was checked by the evaluation of the response to IGg1 and BSA as blood proteins. As a result, the hGH signal was 70 times more than the signal of two non-target proteins, which indicates a high specificity of the fluidic nanobiosensor.