Abstract

BALDERAS-VALADEZ, Ruth Fabiola  and  AGARWAL, Vivechana. Use of porous silicon functionalized with acetylcholinesterase as detection platform for arsenic (III). Ing. invest. y tecnol. [online]. 2017, vol.18, n.3, pp.321-329. ISSN 2594-0732.

Acetylcholinesterase (AChE) functionalized nanostructured porous silicon substrates with two different pore diameters (circular samples with 1.2 cm of diameter), have been evaluated as detection platforms for arsenic (III). Inhibition of enzymatic activity of AChE in the presence of As (III) was used to generate specificity in the proposed silicon based optical As sensors. Prior to AChE attachment, oxidized porous silicon surface was modified through 3-aminopropyl (diethoxy) -methylsilane binding followed by glutaraldehyde and the protein. Each functionalization step was characterized by UV-vis-NIR spectrophotometry coupled with the specular reflectance accessory to monitor the increase in optical thickness due to the infiltration of the molecules. FTIR spectroscopy showed the presence of amide I and II bonds due to the covalent binding of acetylcholinesterase with porous silicon substrate. An enzyme assay based on Ellman's reagent was used to test the enzymatic activity of acetylcholinesterase immobilized on porous silicon as well as its inhibition in the presence of As (III). The detection system of the reaction progress was based on the change in the effective optical thickness of the film revealed as a shift in the reflectivity spectra (method referred as reflective interferometric Fourier transform spectroscopy). The optical response of the modified substrates in the presence of As (III) was compared with the control sample and revealed the detection limit of 0.77 µM.

Keywords : Sensor; detection of arsenic; porous silicon; RIFTS.