TiO2 photocatalytic degradation of cholesterol: SIMS study. (17th July 2012)

• Record Type: Journal Article
• Authors: Prochazka, M.; Stupavska, M.; Jerigova, M.; Velic, D.
• Is Part Of: Surface and interface analysis. Volume 45:Number 1(2013:Jan.)
• Page Start: 22
• Page End: 26
• Publication Date: 2012-07-17
• Subjects: Surfaces (Physics) -- Periodicals; Surface chemistry -- Periodicals; Thin films -- Periodicals; 541.33
• DOI: 10.1002/sia.5120
• Languages: English
• ISSNs: 0142-2421

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>TiO<sub>2</sub> is an efficient photocatalyst for chemical degradation. Nanocrystalline TiO<sub>2</sub> is used in the form of film supported on glass substrate. Since the photocatalytic process is occurring on the surface, a surface‐sensitive technique as a direct probe is desirable. In order to study TiO<sub>2</sub> photoactivity and photodegradation of cholesterol, as a model biomolecule, secondary ion mass spectrometry is utilized. Cholesterol (C<sub>27</sub>H<sub>46</sub>O), stated as M, with mass of 386.65 u, adsorbed on TiO<sub>2</sub> surface, activated with water, and irradiated with different ultraviolet (UV) exposure times is characterized under impact of 25‐keV Bi<sup>+</sup> primary ions. The molecular positive ions in the forms of M–OH and M–H with masses of 369.3 u and 385.3 u, respectively, are of main interest. Due to the specific group of OH, the M‐OH molecular ion might be considered as the primary identification species of the intact cholesterol molecule. The intensities of cholesterol fragment ions M–C<sub>5</sub>H<sub>10</sub>, M–C<sub>7</sub>H<sub>14</sub>, M–C<sub>7</sub>H<sub>14</sub>OH, M + C<sub>4</sub>H<sub>7</sub>, M + C<sub>4</sub>H<sub>9</sub>O, M + C<sub>4</sub>H<sub>9</sub>O<sub>2</sub>, M + C<sub>8</sub>H<sub>15</sub>, and 2 M–2(C<sub>8</sub>H<sub>17</sub>), 2 M–2(C<sub>7</sub>H<sub>15</sub>) decrease significantly after 7 h of UV exposure. Intensities of M–OH and M–H peaks decrease after 24 h by 88% and 62%, respectively. These measurements show the potential to degrade cholesterol, as a main bacteria membrane component and in such a way to terminate bacteria effectively. Copyright © 2012 John Wiley & Sons, Ltd.</p> </abstract>