Nonlinear optical characteristic curve of protein (BSA)
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RESEARCH ARTICLE
Nonlinear optical characteristic curve of protein (BSA) E. Hoque1 • M. K. Biswas1 • H. M. Syfuddin2 • S. M. Sharafuddin1 S. K. Das1 • Y. Haque1
•
Received: 19 December 2019 / Accepted: 13 July 2020 Ó The Optical Society of India 2020
Abstract The third-order nonlinear optical property, nonlinear refractive index (n2 ) of Bovine Serum Albumin has been measured with the reagent Coomassie Brilliant Blue (R-250) by varying the incident laser intensity at the wavelength 514 nm. The closed aperture Z-scan technique, with a chopped laser, has been used to measure n2 and the obtained results are of the order of 107 esu. A variation of one order is also observed with the increase in the dye (R-250) concentration. An approach to determine the optical biomarker is also described with the help of a characteristic curve. Keywords Nonlinear optical methods Nonlinear refractive index BSA protein Characteristic curve
Introduction The physical processes, i.e., thermal, electronic, molecular etc., of materials are the source of the nonlinear refractive index (n2 ). A brief description on the measurement process of nonlinear optical properties is discussed by de Araujo et al. [1]. The Z-scan technique is an experimental process to measure the n2 of an optically transparent thin-layered solid material or liquid [2, 3]. Due to the simplicity and good accuracy of the Z-scan technique, it has already
& E. Hoque [email protected] 1
Department of Physics, Shahjalal University of Science and Technology, Sylhet, Bangladesh
2
Department of Biochemistry and Molecular Biology, Shahjalal University of Science and Technology, Sylhet, Bangladesh
gained wide spread popularity over the other methods. On the other hand, proteins are most abundant in the biofunctional world. The functions of various proteins are the key to all functions in a biological being. The detection and measurement of protein concentration in the medium can provide valuable information about the source (RNA / DNA) that created the protein [4]. An easy optical way of detecting and measuring the protein and its concentration will have a lot of pharmaceutical applications. The concentrations of total protein and albumin, with the help of the nonlinear refractive index measurement, shows a similar result as obtained by the conventional colorimetric method [5]. In the case of blood glucose concentration measurement, it is also found to be in good agreement with the colorimetric method [6]. Such measurements on Bovine Serum Albumin (BSA) concentrations also shows a linear relationship [7]. The goal of such a study was to identify the order of functionality of kidney or liver of humans. Research using nonlinear optics is ongoing, where by means of Second Harmonic Generation (SHG), Imaging Biomarker detection is leading to the identification of colon [8, 9], kidney [10] and corneal [11] cancer. In this type of detection, the cancer cells are observed for qualitative and quantitative identification. Ovarian cancer tissue cells have been observed to
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