期刊
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
卷 448, 期 -, 页码 147-153出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.colsurfa.2014.02.026
关键词
Gold nanoparticles; Poly-(gamma-glutamic acid); pH responsive; Colorimetric probe
资金
- National Natural Science Foundation of China [31201376]
- National Key Technology RD Program [2012BAD32B08]
- Scientific Research Fund of Heilongjiang Provincial Education Department [12531152]
- Material Science and Engineering College of Northeast Forestry University in China
A rapid and simple real-time visualization of colorimetric method for pH-sensitive was development based upon the aggregation of poly-(gamma-glutamic acid)-stabilized gold nanoparticles (PGA-AuNPs). The gold nanocrystal seed-mediated approach using cetyltrimethylammonium bromide (CTAB) as a stabilizing surfactant was commonly used to make large quantities of AuNPs. Electrostatic self-assembly technique was used to assemble negatively charged PGA on the surface of positively charged CTAB-capped AuNPs. Results showed that decrease in pH near 5-6 and increase in pH near 8-9 led to the aggregation of PGA-AuNPs. The colorimetric probe showed a sensitive response to pH variation between 1 and 9. The change in aggregation behavior with pH occurred within a narrow range of pH from 5 to 6 (pKa similar to 4.5-5.5). The decrease in the solution pH gradually converted the side chains of PGA from deprotonate form to protonate form. Such change switching could weaken electrostatic interactions with the modified AuNPs and thus accelerate their release and aggregation. The helix-coil transition of PGA indicated that the aggregation of PGA-AuNPs corresponded to the transition in the secondary structure of the polyacid. (C) 2014 Elsevier B.V. All rights reserved.
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