Nanotechnology is one of the key technologies of twenty first century. It involves engineering with materials that have size dimension in nanometer range. As important biological entities like virus, pores of biological membranes, proteins, etc also share their sizes in the nanometer ranges; there has been an extensive application of nanotechnology in biology and biomedicine. Nanomaterial based drug delivery offers one of the most useful techniques to administer therapeutics in living cells and tissues. Mesoporous silica nanomaterials act as excellent hosts to store and deliver guest molecules. In this book, research topics on the development of mesoporous silica nanomaterials as a stimuli responsive and controlled release delivery agents have been discussed. Magnetic nanoparticles were utilized for targeting the drug delivery assembly to a site of interest and induce stimuli responsive drug release in 'proof of principle' studies. The work described in this book is expected to provide a rational approach towards designing targeted and stimuli responsive smart drug delivery systems.