1 Chemically Triggered Biodelivery is Possible Using Metal- Organic Sol-Gel Synthesis By Vadim G. Kessler * , Gulaim A. Seisenbaeva, Maria Unell, and Sebastian Håkansson Abstract. Modification of titanium alkoxides with hydrophilic, basic, positively chargeable ligands, offers the possibility to prepare sols that can be transferred into aqueous medium without immediate phase separation. The resulting titania hydrosols consist of micellar particles with small but rather well defined crystalline cores (about 2 nm) surrounded by amorphous shells. This structure facilitates self-assembly of the particles into continuous oxide shells around the living cells, which generally have a negatively charged surface. The shells are then incorporated further into the emerging gel structure. The shells are penetrable only for very small molecules such as water or oxygen and provide efficient isolation of the encapsulated biomaterial from the surrounding medium, which makes these shells principally different from the earlier reported silica encapsulates. The resulting colloid media are highly biocompatible and offer attractive possibilities for encapsulation of living organisms with a possibility of subsequent chemically and biochemically triggered release (bio-delivery), based on dissolution of titania nanoparticles on interaction with chelating carboxylate ligands such as citrate ions. Application of titanium alkoxides, modified with anti-inflammatory drugs such as ibuprofen or penicillamine as ligands, as a component of a precursor system offers an approach to gels loaded with pharmaceuticals that can be further released with a considerable * Prof. V.G.Kessler, Dr. G.A.Seisenbaeva, Department of Chemistry, SLU P.O. Box 7015, 750 07 Uppsala (Sweden) Dr. S.Håkansson, Dr. M.Unell Department of Microbiology, SLU P.O. Box 7025, 750 07 Uppsala (Sweden)