Final Activity Report Summary - DRUG DELIVERY SYSTEM (Multifunctional Dendrimers as targeted drug delivery systems) Around the world, one person dies every four seconds due to cancer and related complications. This shocking data urges the scientists to explore new avenues for possible cures. One of the promising areas of research involves targeted drug delivery where the medicine is carried by a vehicle that finds and gets taken up by tumour cells and then kills the cancer. The initial research involves exploration of new vehicles with high carrier capacity which is followed by finding the right combination of the vehicle, drug and the targeting moiety. In this on-going research, we are trying to explore dendrimers as drug delivery agents. The research involves synthesis of novel segment block dendrimers, attachment of the desired drug and targeting groups on these dendrimers and finally their evaluation in vitro as cancer chemotherapy agents. Multifunctional dendrimers have a high potential for drug delivery applications as they accommodate a high density and wide variety of functional groups on their surface. Along with their well-defined molecular structure, segmented spherical construction of dendrimers offers an interesting architecture. While one of these segments is ornamented with active drug molecules, the other one can be decorated with targeting groups. Such a dual design will allow the plasma level of the drug to stay at the desired level for a longer duration, and thus increase its pharmaceutical efficiency. Direct application of drug molecules to the diseased tissue or organ increases the effect of the therapy and decreases the side effects. Therapeutic efficacy of drugs is often diminished due to their low bioavailability, insolubility, toxicity and their decomposition under biological conditions. Conjugating drug molecules onto dendrimers containing targeting moieties can improve all of these shortcomings. The research that started with this project has evolved into three parts: The first part is the synthesis of dendrons (dendrimer pieces) with targeting groups, the second part is the attachment of drug molecules to another dendron and the third and final part is the development of methodology for putting these two pieces together. The most important scientific achievement of the project is the synthesis of bone targeting dendrons and the methodologies developed to successfully join the two pieces to yield dendrimers.