Quantitative Determination of Competitive Molecular Adsorption on Gold Nanoparticles Using Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy

Citations Over TimeTop 10% of 2011 papers

Abstract

Surface-sensitive quantitative studies of competitive molecular adsorption on nanoparticles were conducted using a modified attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy method. Adsorption isotherms for thiolated poly(ethylene glycol) (SH-PEG) on gold nanoparticles (AuNPs) as a function of molecular mass (1, 5, and 20 kDa) were characterized. We find that surface density of SH-PEG on AuNPs is inversely proportional to the molecular mass (M(m)). Equilibrium binding constants for SH-PEG, obtained using the Langmuir adsorption model, show the binding affinity for SH-PEG is proportional to M(m). Simultaneous competitive adsorption between mercaptopropionic acid (MPA) and 5 kDa SH-PEG (SH-PEG5K) was investigated, and we find that MPA concentration is the dominant factor influencing the surface density of both SH-PEG5K and MPA, whereas the concentration of SH-PEG5K affects only SH-PEG5K surface density. Electrospray differential mobility analysis (ES-DMA) was employed as an orthogonal characterization technique. ES-DMA results are consistent with the results obtained by ATR-FTIR, confirming our conclusions about the adsorption process in this system. Ligand displacement competitive adsorption, where the displacing molecular species is added after completion of the ligand surface binding, was also interrogated by ATR-FTIR. Results indicate that for SH-PEG increasing M(m) yields greater stability on AuNPs when measured against displacement by bovine serum albumin (BSA) as a model serum protein. In addition, the binding affinity of BSA to AuNPs is inhibited for SH-PEG conjugated AuNPs, an effect that is enhanced at higher SH-PEG M(m) values.

Related Papers

• → Resveratrol, Genistein, and Curcumin Bind Bovine Serum Albumin(2010)396 cited
• → Effects of pH and metal ions on the conformation of bovine serum albumin in aqueous solution An attenuated total reflection (ATR) FTIR spectroscopic study(1996)34 cited
• Effect of ferric iron on interaction between breviscapinun and bovine serum albumin(2013)
• Flouorescence spectrometric study of interaction between complex [Cu(Glu·Arg)]SO_4·5H_2O and bovine serum albumin(2013)