Reversible Association of Thermoresponsive Gold Nanoparticles:  Polyelectrolyte Effect on the Lower Critical Solution Temperature of Poly(vinyl methyl ether)

2006 ◽  
Vol 110 (13) ◽  
pp. 6768-6775 ◽  
Author(s):  
Rama Ranjan Bhattacharjee ◽  
Mukut Chakraborty ◽  
Tarun K. Mandal
Keyword(s):  
Gold Nanoparticles ◽  
Methyl Ether ◽  
Lower Critical Solution Temperature ◽  
Solution Temperature ◽  
Vinyl Methyl ◽  
Critical Solution Temperature ◽  
Vinyl Methyl Ether ◽  
Reversible Association ◽  
Polyelectrolyte Effect

scholarly journals Conformational Stability of Poly (N-Isopropylacrylamide) Anchored on the Surface of Gold Nanoparticles

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 443
Author(s):  
Runmei Li ◽  
Cong Cheng ◽  
Zhuorui Wang ◽  
Xuefan Gu ◽  
Caixia Zhang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Temperature Sensitivity ◽  
Electrostatic Interaction ◽  
Strong Interaction ◽  
Lower Critical Solution Temperature ◽  
Conformational Stability ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Critical Solution Temperature ◽  
Temperature Variations

To verify the temperature sensitive failure of poly (N-isopropylacrylamide) (PNIPAM) anchored on the surface of gold nanoparticles (AuNPs), the UV-Vis spectra with temperature variations of the following aqueous solutions respectively containing AuNPs-PNIPAM, Au-PNIPAM/PNIPAM, PNIPAM, in different media (including salt, ethanol, HCl and cetyltrimethylammoniumbromide (CTAB)), were systematically determined. The results indicated that the UV-Vis spectrum of AuNPs-PNIPAM suspension hardly changed even above the Lower Critical Solution Temperature (LCST) of PNIPAM, but that of Au-PNIPAM/PNIPAM sharply increased only in absorbance intensity. A possible mechanism of the failed temperature sensitivity of PNIPAM anchored on the surface of AuNPs was proposed. Being different from free PNIPAM molecules, a strong interaction exists among PNIPAM molecules anchored on the surface of AuNPs, restraining the change in conformation of PNIPAM. The temperature sensitivity of Au-PNIPAM/PNIPAM originates from the free PNIPAM molecules rather than the anchored PNIPAM one. The changing electrostatic interaction could effectively regulate the aggregation behavior of AuNPs-PNIPAM and enhance its sensitivity to temperature.

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