期刊
LANGMUIR
卷 34, 期 5, 页码 2039-2045出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.langmuir.7b03743
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资金
- National Science Foundation (NSF) [CBET-1055652]
- RI NSF EPSCoR [OIA-1655221]
- Div Of Chem, Bioeng, Env, & Transp Sys
- Directorate For Engineering [1055652] Funding Source: National Science Foundation
We have investigated the surface activity of poly(ethylene glycol) (PEG) -coated silver nanoparticles (AgPEG) in the presence or absence of lipid monolayers comprised of monounsaturated dioleoylphosphocholine and dioleoylphosphoglycerol (DOPC/DOPG; 1:1 mol ratio). Dynamic measurements of surface pressure demonstrated that Ag-PEG were surface-active at the air/water interface. Surface excess concentrations suggested that at high Ag-PEG subphase concentrations, Ag-PEG assembled as densely packed monolayers in the presence and absence of a lipid monolayer. The presence of a lipid monolayer led to only a slight decrease in the excess surface concentration of Ag-PEG. Surface pressure area isotherms showed that in the absence of lipids Ag-PEG increased the surface pressure up to 45 mN m(-1) upon compression before the Ag-PEG surface layer collapsed. Our results suggest that surface activity of Ag-PEG was due to hydrophobic interactions imparted by a combination of the amphiphilic polymer coating and the hydrophobic dodecanethiol ligands bound to the Ag-PEG surface. With lipid present, AgPEG + lipid surface pressure area (pi-A) isotherms reflected Ag-PEG incorporation within the lipid monolayers. At high Ag-PEG concentrations, the pi-A isotherms of the Ag-PEG + lipid films closely resembled that of Ag-PEG alone with a minimal contribution from the lipids present. Analysis of the subphase silver (Ag) and phosphorus (P) concentrations revealed that most of the adsorbed material remained at the air/lipid/water interface and was not forced into the aqueous subphase upon compression, confirming the presence of a composite Ag-PEG + lipid film. While interactions between water-soluble nanoparticles and lipids are often considered to be dominated by electrostatic interactions, these results provide further evidence that the amphiphilic character of a nanoparticle coating can also play a significant role.
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