Biomaterials in the nano-era

Surface Chemistry, Crystal Structure, Size and Topography Role in the Albumin Adsorption Process on TiO2 Anatase Crystallographic Faces and Its 3D-Nanocrystal: A Molecular Dynamics Study

TiO2 is widely used in biomaterial implants. The topography, chemical and structural properties of titania surfaces are an important aspect to study. The size of TiO2 nanoparticles synthetized by sol–gel method can influence the responses in the biological environment, and by using appropriate heat treatments different contents of different polymorphs can be formed. Protein adsorption is a crucial step for the biological responses, involving, in particular, albumin, the most abundant blood protein. In this theoretical work, using molecular mechanics and molecular dynamics methods, the adsorption process of an albumin subdomain is reported both onto specific different crystallographic faces of TiO2 anatase and also on its ideal three-dimensional nanosized crystal, using the simulation protocol proposed in my previous theoretical studies about the adsorption process on hydrophobic ordered graphene-like or hydrophilic amorphous polymeric surfaces. The different surface chemistry of anatase crystalline faces and the nanocrystal topography influence the adsorption process, in particular the interaction strength and protein fragment conformation, then its biological activity. This theoretical study can be a useful tool to better understand how the surface chemistry, crystal structure, size and topography play a key role in protein adsorption process onto anatase surface so widely used as biomaterial.

Light-Responsive Nanoparticles for Highly Efficient Cytoplasmic Delivery of Anticancer Agents

Stimuli-responsive nanostructures have shown great promise for intracellular delivery of anticancer compounds. A critical challenge remains in the exploration of stimuli-responsive nanoparticles for fast cytoplasmic delivery. Herein, near-infrared (NIR) light-responsive nanoparticles were rationally designed to generate highly efficient cytoplasmic delivery of anticancer agents for synergistic thermo-chemotherapy. The drug-loaded polymeric nanoparticles of selenium-inserted copolymer (I/D-Se-NPs) were rapidly dissociated in several minutes through reactive oxygen species (ROS)-mediated selenium oxidation upon NIR light exposure, and this irreversible dissociation of I/D-Se-NPs upon such a short irradiation promoted continuous drug release. Moreover, I/D-Se-NPs facilitated cytoplasmic drug translocation through ROS-triggered lysosomal disruption and thus resulted in highly preferable distribution to the nucleus even in 5 min postirradiation, which was further integrated with light-triggered hyperthermia for achieving synergistic tumor ablation without tumor regrowth.