Nano-/Microfabrication of Biomaterials

The surface composition and functionality of biomaterials and scaffolds are the most important factors for their applications in biomedical fields and tissue regeneration. Bulk and surface properties of biomaterials influence vital cell activities such as cell adhesion, proliferation, extracellular matrix secretion, and differentiation. Nano-/microstructural control is found to be another key factor in tailoring the bioactivity of material surfaces. The morphological/topographical designing of the grafts is also proved to be a strategic approach in improving the bioactivity and biological responses of the biomaterial. Furthermore, the nano-/microstructured grafts possess higher specific surface area, which will provide much more adsorption sites to adsorb bioactive molecules. In view of these specialties of the biomaterials, several investigators are invited to contribute original research findings that can stimulate continuing efforts to understand the dimensions of the polymers and bioceramics as well as their composites essentially with bioactive compositions along with 2D/3D nano-/microlevel surface structures. The special issue is divided into three categories based on the key words of nanoparticles, surface control, and 3D scaffolds. The published works are briefly addressed as follows. In the category of nanoparticles, S.-J. Han et al. prepared herceptin-immobilized CdSe/ZnS core-shell quantum dots (QDs). Mean size of the quantum dots (28 nm) as determined by dynamic light scattering was increased up to 86 nm after herceptin immobilization. It was found, from in vitro cell culture experiment, that keratin forming cancer cells (KB) were well proliferated in the presence of herceptin-conjugated QDs (QD-Her) while most of breast cancer cells (SK-BR3) were dead. The data from confocal laser scanning microscope showed that the QD-Her specifically bound to the membrane of SK-BR3 and almost saturated after 6 hours of incubation. This result suggested that growth signal of the breast cancer cell is completely inhibited by specific binding of the herceptin to the Her-2 receptor of SK-BR3 membrane, resulting in cell death. A. Takahashi et al. reported impact of core-forming segment structure on drug loading in biodegradable polymeric micelles using PEG-b-poly(lactide-co-depsipeptide) block copolymers. As a result, the drug loading increased with increase in the mole fraction of depsipeptide unit in the hydrophobic segments. Y. Huang et al. prepared reduction-triggered breakable poly-meric micelles incorporated with methotrexate (MTX) using amphiphilic PAA-g-PEG copolymers having S–S bonds in the backbone. The drug loading content and drug loading efficiency increased along with more hydrophobic segments in the copolymers. In reductive environments, the entire MTX payload could be quickly released due …