Document Type : Research Paper
Authors
1
Department of Nanobiotechnology and Biomimetic, Faculty of Biological Sciences Engineering, Faculty of Interdisciplinary Sciences and Technologies, University of Tehran, Tehran, Iran
2
Department of Nanobiotechnology and Biomimetic, Faculty of Life Sciences Engineering, Faculty of Interdisciplinary Sciences and Technologies, University of Tehran, Tehran, Iran
3
Department of Microbiology, Faculty of Medicine, Mustafa Kemal Hatay University, Antakya-Hatay, Turkiye
4
Department of Medical Technology and Tissue Engineering, Faculty of Life Sciences Engineering, Faculty of Interdisciplinary Sciences and Technologies, University of Tehran, Tehran, Iran
5
Department of Pharmaceutics and Nanotechnology, Faculty of Pharmacy, Birjand University of Medical Sciences, Birjand, Iran
Abstract
Hypothesis: The detection of pathogenic bacteria in food and clinical samples is valuable, and diagnosing them in a short period of time remains a challenge. In this research, an optical nanosensor based on Fourier transform spectroscopy from a porous silicon integrated with gelatin hydrogel was used to detect bacterial growth. Gelatin is a pH-sensitive hydrogel that swells quickly with the growth of bacteria and changes in the pH of the environment. The hybrid of this hydrogel with porous silicon nanostructure creates a pH-sensitive structure whose refractive index changes with bacterial growth and pH changes. This change causes a variation in the effective optical thickness of the hybrid nanostructure, which can be investigated using Fourier transform spectrometry
Methods: First, electrochemical etching was used to fabricate porous silicon. In the next step, the oxidized porous silicon surface was functionalized with APTES, which leaves amine groups on the surface for conjugation with gelatin .Finally, the swelling behavior of hydrogel in hybrid was investigated in response to environmental pH changes and then in the presence of different concentrations of bacteria
Findings: By X-ray energy dispersive spectroscopy in mapping mode and checking the distribution of elements, the penetration of the gel into the pores of porous silicon was observed. By analyzing the Fourier transform spectrometry of the porous siliconegelatin hybrid in the presence of buffers with different pH levels, it was determined that due to the swelling of the gel layer and the refractive index of this layer approaching the refractive index of the surrounding environment, the location of the first peak used as the fluid peak can be considered as a diagnostic point. The results showed that this structure has the ability to detect changes in environmental pH as well as bacterial growth in the concentration range of 102 to 105 cfu/mL.
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