Characterization of protein adsorption onto silica nanoparticles: influence of pH and ionic strength
Autor: | Gerhard H. Findenegg, Jens Meissner, Albert Prause, Bhuvnesh Bharti |
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Rok vydání: | 2015 |
Předmět: |
Electrostatic interactions
Polymers and Plastics Chemistry Protein Lysozyme Inorganic chemistry Ionic bonding Nanoparticle Silica Electrolyte ß-lactoglobulin Colloid and Surface Chemistry Isoelectric point Adsorption Invited Article Ionic strength Monolayer Materials Chemistry Nanoparticles Organic chemistry Physical and Theoretical Chemistry Protein adsorption |
Zdroj: | Colloid and Polymer Science |
ISSN: | 1435-1536 0303-402X |
DOI: | 10.1007/s00396-015-3754-x |
Popis: | The adsorption of lysozyme and ß-lactoglobulin onto silica nanoparticles (diameter 21 nm) was studied in the pH range 2–11 at three different ionic strengths. Since the two proteins have a widely different isoelectric point (pI), electrostatic interactions with the negative silica surface lead to a different dependence of adsorption on pH. For lysozyme (pI ≈ 11), the adsorption level increases with pH and reaches a value corresponding to about two close-packed monolayers at pH = pI. In the multilayer adsorption region near pI, added electrolyte causes a decrease in adsorption, which is attributed to the screening of attractive interactions between protein molecules in the first and second adsorbed layer. For ß-lactoglobulin (pI ≈ 5), a pronounced maximum of the adsorbed amount is found at pH 4 in the absence of salt. It is attributed to the adsorption of oligomers of the protein that exist in the solution at this pH. An inversion in the influence of salt on the adsorbed amount occurs at pH > pI, where the protein and the surface are both negatively charged. This inversion is attributed to the screening of the repulsive protein-surface and protein–protein interactions. The adsorption isotherms were analyzed with the Guggenheim–Anderson–De Boer (GAB) model, which allows for two adsorption states (strongly and weakly bound protein). |
Databáze: | OpenAIRE |
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