Inorganic Nanoparticle Materials for Controlled Drug Delivery Systems

The history of drug delivery began with a German scientist called Paul Ehrlich (1854-1915) [1]. The reasoning for the design of active agents should be selective and only attack the disease-causing organism. However, to reach its target, the drug could be delivered along with the agent of selectivity forming a kind of magic bullet, created to only kill the organism targeted [2]. This idea was used as a script for the movie Dr. Ehrlich’s Magic Bullet in 1940. Hence, in the 1950s, the rst related studies using microencapsulated drug particles appeared [3]. In the 1960s, leading research provided an initial understanding of pharmacokinetics [4] and therapeutic drug monitoring. The utilization of polymers for drug delivery began in the 1960s when scientists had developed systems combining previous understanding about pharmacokinetics, biological interface, and biocompatibility. However, only a few studies had succeeded in developing new drug delivery systems due to the slow release of large molecular weight compounds. The work of Davis [5, 6] and Gimbrone et al. [7] was one of these that achieved partial success. However, the polymers used in these studies proved to be unsuitable, since they caused inammation in animal tissue. In 1976, the rst drug delivery system based on polymers for slow release of macromolecules without inammatory issues was described [8, 9]. After this, several other systems were developed, but only in 1980 novel proposals emerged reporting a pH-sensitive releasing system [10] and a cell-specic targeting strategy using liposomes [11, 12]. Later in 1987, it was described long-circulating liposome providing new grounds for effective drug.