Electrosurface Properties of Nanostructured Silica Assessed by EPR of Molecular pH Labels / Kovaleva Elena G.,Molochnikov Leonid S.,Osipova Victoria A.,Stepanova Darya P.,Reznikov Vladimir A. // APPLIED MAGNETIC RESONANCE. - 2015. - V. 46, l. 12. - P. 1367-1382.

ISSN/EISSN:

0937-9347 / 1613-7507

Type:

Article

Abstract:

Three techniques of spin labeling have been applied to nanostructured SiO2 and have been tested by electron paramagnetic resonance spectroscopy of pH-sensitive nitroxide radicals (NRs). The best technique was based on preliminary interaction of the pH-sensitive NR bromomethyl-2,2,3,5,5-pentamethylimidazoline-1-oxyl with aminopropyltriethoxy-silane (APTES) in the presence of trioctylamine and further treatment of the nanostructured SiO2 with the hydrolyzed product and acetic anhydride. It was found that there are two types of location of the pH-sensitive NRs (spin labels) on the surface of nanostructured silica. The spin labels of the first type located near the surface of nanostructured SiO2 ({''}slow-motional{''} NR) have been used to measure near-surface electrical potential at the site of NR N-O-aEuro cent fragment location, q equal to -90 mV. The NR molecules of the second type which were positioned well far from the nanostructured SiO2 surface ({''}fast-motional{''} NRs) were employed to establish the regularities of mutual changes in the NR form and nanoparticle surface charge with variations in pH of external bulk solution (pH(ext)). The pH-sensitive NRs covalently attached to the SiO2 surface were successfully employed for the study of surface charge in the drying process with a rise of temperature up to 375 K. A negative surface charge was shown to decrease due to reducing an ionization degree of the surface silanol groups. This process was found to be reversible at re-adsorption of water molecules.

Author keywords:

GOLD NANOPARTICLES; INHIBITION; INDICATORS; MEMBRANES; RADICALS; BILAYERS; POLARITY; ACIDITY; PROBES

DOI:

10.1007/s00723-015-0704-1

Web of Science ID:

ISI:000364504700005

Соавторы в МНС:

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Другие поля

Поле	Значение
Month	DEC
Publisher	SPRINGER WIEN
Address	SACHSENPLATZ 4-6, PO BOX 89, A-1201 WIEN, AUSTRIA
Language	English
EISSN	1613-7507
Keywords-Plus	GOLD NANOPARTICLES; INHIBITION; INDICATORS; MEMBRANES; RADICALS; BILAYERS; POLARITY; ACIDITY; PROBES
Research-Areas	Physics; Spectroscopy
Web-of-Science-Categories	Physics, Atomic, Molecular \& Chemical; Spectroscopy
Author-Email	gek1969@bk.ru lsmolochnikov@gmail.com osipova.sva@gmail.com darya.st.91@mail.ru reznikov@nioch.nsc.ru
ResearcherID-Numbers	Kovaleva, Elena/M-7400-2016 Stepanova, Daria/M-8039-2016
ORCID-Numbers	Kovaleva, Elena/0000-0002-3111-345X
Funding-Acknowledgement	Russian Foundation for Basic Research {[}14-03-00898]; State Task of the Ministry of Education (RF) {[}4.1626.2014/K]
Funding-Text	This work was supported by the Russian Foundation for Basic Research (project no. 14-03-00898) and by the State Task of the Ministry of Education (RF) no. 4.1626.2014/K.
Number-of-Cited-References	34
Usage-Count-Last-180-days	2
Usage-Count-Since-2013	20
Journal-ISO	Appl. Magn. Reson.
Doc-Delivery-Number	CV8CR