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The interaction between gold nanoparticles and cationic and anionic dyes: enhanced UV-visible absorption

Narband, N; Uppal, M; Dunnill, CW; Hyett, G; Wilson, M; Parkin, IP; (2009) The interaction between gold nanoparticles and cationic and anionic dyes: enhanced UV-visible absorption. PHYS CHEM CHEM PHYS , 11 (44) 10513 - 10518. 10.1039/b909714g.

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Abstract

The interactions of charge stabilised gold nanoparticles with cationic and anionic dyes are reported. The nanoparticles were synthesised by the Turkevich citrate reduction method. It was found that when a solution of thiazine dye is titrated against gold citrate hydrosol, at a critical concentration of dye there is an enhanced maximum absorption in the dye. The extinction coefficient is increased up to ten-fold. This enhancement was observed for a number of cationic thiazine dyes, of which methylene blue and toluidine blue are established light-activated antimicrobial agents. The same enhancement was not observed for anionic, acidic dyes such as rose bengal which showed no communication with the gold nanoparticles and showed UV-visible titration experiments with well formed isosbestic points. By studying the interaction of the dye and gold nanoparticles under conditions of different ionic strength and by using a zetasizer and TEM to measure the gold nanoparticle size it was demonstrated that the cause of enhancement was not due to nanoparticle aggregation. It is proposed that thiazine cationic dyes coordinate around a gold nanoparticle and give significantly enhanced UV-visible absorptions.

Type:Article
Title:The interaction between gold nanoparticles and cationic and anionic dyes: enhanced UV-visible absorption
DOI:10.1039/b909714g
Keywords:STAPHYLOCOCCUS-AUREUS, TOLUIDINE BLUE, LETHAL PHOTOSENSITIZATION, PHOTODYNAMIC THERAPY
UCL classification:UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Eastman Dental Institute > Microbial Diseases
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Chemistry

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