Inorganic-organic hybrids for biomedical applications

Flexible sol-gel procedure is an excellent route to prepare inorganic-organic hybrids where homogenous precursor solutions yield solid or porous gels and composites in the size from macroscopic ranges (cm, mm) to microscopic (μm) and nanoscopic (nm) ranges. The present chapter first provides short introduction of inorganic-organic hybrids: historical aspects, constitution, and inorganic and organic components to be hybridized as well as their possible biomedical applications. Their biocompatibility is the most significant, and it is discussed in detail in terms of the fixation of various hybrid materials with hard and soft tissues. The primary topics are the behaviors of inorganic species like Si-OH, Ti-OH, calcium ions, and hydroxycarbonate apatite (HCA) deposition, as well as the roles of short peptides like arginine-glycine-aspartate (Arg-Gly-Asp; RGD) and mediating layers. Inorganic-organic layers with Ti-O or P-O favor anti-blood clotting (thrombosis) and polymer-apatite bonding in dentistry. Described are several biomedically applicable porous hybrids among a few silanes, natural polymers (gelatin, chitosan, collagen, and silk fibroin), and synthetic polymers poly(dimethylsilane), poly(lactic acid), and poly (caprolactone). Some are promising to repair damaged nerve systems. Electrospinning, bioprinting, and liquid phase deposition techniques are presented as versatile methods to fabricate fibrous membranes, 3-D architecture, and intermediating oxide layers. Hybrid nanoparticles are introduced as the promising drug delivery and therapeutic vehicles, such as cerasomes (ceramic + liposome), magnetoliposomes, nanomachines, or mesoporous silica. Finally, a few paragraphs stress the significance of quantum dots in the biomedical fields like biosensing or bioimaging.