BSA adsorption onto negatively and positively charged polystyrene nanoparticles was investigated. The nanoparticles were characterized in terms of particle size, zeta potential, surface group density, and morphology. The adsorption behavior of BSA on the particle surface, as a function of pH and overall charge of the particle, was studied using ITC. Different thermodynamic data such as enthalpy changes upon binding and stoichiometry of the systems were determined and discussed. The degree of surface coverage with BSA was calculated using the thermodynamic data. The cellular uptake of particles before and after BSA adsorption was studied using HeLa cells in the presence and absence of supplemented FCS in the cell culture medium.

5,6-Benzo-2-methylene-1,3-dioxepane (BMDO) is used to obtain degradable polymeric nanoparticles via a statistical free-radical copolymerization with MMA and styrene in direct miniemulsion. The nanoparticles are analyzed by means of IR, NMR, DLS, SEM, and TEM. They show excellent cellular uptake and drug delivery properties. The cellular uptake into HeLa cells of particles resulting from copolymerization of BMDO with styrene is drastically enhanced compared to pure polystyrene. As a model drug system, paclitaxel is incorporated in PBMDO particles and its release and the effect on HeLa cells is studied and compared to commercial drug formulations. It is found that a drug delivery system based on PBMDO shows an excellent pharmacological effect.

Titanium that is covered with a native oxide layer is widely used as an implant material; however, it is only passively incorporated in the human bone. To increase the implant-bone interaction, one can graft multifunctional phosphonic compounds onto the implant material. Phosphonate groups show excellent adhesion properties onto metal oxide surfaces such as titanium dioxide, and therefore, they can be used as anchor groups. Here, we present an alternative coating material composed of phosphonate surface-functionalized polystyrene nanoparticles synthesized via free radical copolymerization in a direct (oil-in-water) miniemulsion process. Two types of functional monomers, namely, vinylphosphonic acid (VPA) and vinylbenzyl phosphonic acid (VBPA), were employed in the copolymerization reaction. Using VBPA as a comonomer leads to particles with a higher density of surface phosphonate groups in comparison to those obtained with VPA. VBPA-functionalized particles were used for the coating formation on the titanium surface. The particles monolayer was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) employing titanium and silicium tip with the native OH groups. Force versus distance curves proves the strong adhesion between the phosphonated particles and the titanium (or silicium) surfaces in contrast to the nonfunctionalized polystyrene particles. Finally, as a proof of concept, the particles adhered to the surface were further used to nucleate hydroxyapatite, which has high potential for bioimplants.

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