Surface Charge Control through the Reversible Adsorption of a Biomimetic Polymer on Silica Particles

The control of the physicochemical properties of silica particles is of paramount importance to achieve full functionality in specific applications. A novel facile method of silica particle synthesis, requiring only two reactants, was developed. Control of the surface charge of these newly synthesized silica particles was achieved via the rapid electrostatic adsorption and acidic desorption of the branched, biomimetic polymer, polyethylenimine (PEI). Successful adsorption/desorption of PEI was supported by ATR-FTIR spectra, an adsorption isotherm, and ζ-potential curves. PEI adsorption above a threshold PEI concentration was determined to categorically change the topography of the silica particles' ζ-potential curve. The results from our study convey a rapid, reversible, and reliable method of silica particle surface charge control. This may be of particular use in tailoring surface interactions of silica or silica-coated particles for applications in drug delivery, biomedical technologies, catalysis, and coatings.