Acetylcholinesterase immobilization and characterization, and comparison of the activity of the porous silicon-immobilized enzyme with its free counterpart

Abstract

SynopsisA successful prescription is presented for acetylcholinesterase physically adsorbed on to a mesoporous silicon surface, with a promising hydrolytic response towards acetylthiocholine iodide. The catalytic behaviour of the immobilized enzyme was assessed by spectrophotometric bioassay using neostigmine methyl sulfate as a standard acetycholinesterase inhibitor. The surface modification was studied through field emission SEM, Fourier transform IR spectroscopy, energy-dispersive X-ray spectroscopy, cathode luminescence and X-ray photoelectron spectroscopy analysis, photoluminescence measurement and spectrophotometric bioassay. The porous silicon-immobilized enzyme not only yielded greater enzyme stability, but also significantly improved the native photoluminescence at room temperature of the bare porous silicon architecture. The results indicated the promising catalytic behaviour of immobilized enzyme compared with that of its free counterpart, with a greater stability, and that it aided reusability and easy separation from the reaction mixture. The porous silicon-immobilized enzyme was found to retain 50 % of its activity, promising thermal stability up to 90 • C, reusability for up to three cycles, pH stability over a broad pH of 4-9 and a shelf-life of 44 days, with an optimal hydrolytic response towards acetylthiocholine iodide at variable drug concentrations. On the basis of these findings, it was believed that the porous silicon-immobilized enzyme could be exploited as a reusable biocatalyst and for screening of acetylcholinesterase inhibitors from crude plant extracts and synthesized organic compounds. Moreover, the immobilized enzyme could offer a great deal as a viable biocatalyst in bioprocessing for the chemical and pharmaceutical industries, and bioremediation to enhance productivity and robustness.

Covalent immobilization of acetylcholinesterase on a novel polyacrylic acid‐based nanofiber membrane

“…A. Similar pH values were found to be at pH 8 for AChE immobilized on mesoporous silicon surface , on SiO 2 hybrid membranes , on styrene–maleic anhydride copolymer , and acrylonitrile copolymer membranes .…”

“…5A. Similar pH values were found to be at pH 8 for AChE immobilized on mesoporous silicon surface [31], on SiO 2 hybrid membranes [32], on styrene-maleic anhydride copolymer [33], and acrylonitrile copolymer membranes [7]. The influence of temperature on the activity of the free and immobilized AChE was investigated by varying the temperature from 20 to 40°C and the enzyme activity behaviors were demonstrated in Fig.…”

Inhibition assays of free and immobilized urease for detecting hexavalent chromium in water samples

“…Studies have reported similar results for enzyme immobilized by physical adsorption methods (Chaudhari et al 2005;Saleem et al 2016). The change in the appearance of PS surface observed by SEM confirms the presence of enzyme molecules on PS film.…”

Особенности Дефектообразования В Наноструктурированном Кремнии При Ионном Облучении

“…[6]. Оптические свойства [7,8] пористого кремния были успешно использованы для изготовления датчиков и биосенсоров: например, мезопористый кремний использовался в качестве многоразового биокаталитического устройства [9]. Мезо-и наночастицы кремния биоразлагаемы и биосовместимы [10], являются отличными кандидатами для биосенсоров in vivo [11] и позволяют проводить in vitro диагностику раковых заболеваний на ранних стадиях [12].…”