Integration of nanotechnology and biomedicine has offered great opportunities for the development of nanoscaled therapeutic platforms. Amongst various nanocarriers, mesoporous silica nanoparticles (MSNs) is one of the most developed and promising inorganic materials-based drug delivery system for clinical translations due to their simple composition and nanoporous structure. MSNs possess unique structural features, for example, well-defined morphology, large surface areas, uniform size, controllable structure, flexible pore volume, tunable pore sizes, extraordinarily high loading efficiency, and excellent biocompatibility. Progress in structure control and functionalization may endow MSNs with functionalities that enable medical applications of these integrated nanoparticles such as molecularly targeted drug delivery, multicomponent synergistic therapy, in vivo imaging and therapeutic capability, on-demand/stimuli-responsive drug release, etc. In this chapter, the authors overview MSNs' characteristics and the scientific efforts developed till date involving drug delivery and biomedical applications.
TopNanocarriers And Their Ongoing Challenges
Development of nanoparticle based therapeutics has come a long way since polymer-drug conjugate and first liposomal-drug formulation were reported in 1955 and 1973 respectively (Petros & DeSimone, 2010, Bobo, Robinson, Islam, Thurecht, & Corrie, 2016). Figure 1 presents the nanoparticle based medicines which are approved by the US FDA. Nanoparticles have provided a universal platform for drug delivery owing to their unique characteristics like use of different types of material in their design (e.g. polymer, metal oxides, silica, carbon and metals), accommodation of wide range of bioactive components (e.g. small molecules, proteins, nucleic acids, diagnostics etc.), functionalization with multiple functional groups for drug and gene targeting. Despite several advantages, there are several limitations associated with the nanoparticle based delivery systems like poor drug loading or limited carrying capacity, burst release, inadequate tissue distribution, scale up issues, rapid clearance via reticuloendothelial system, toxicity, and regulatory issues etc (Couvreur, 2013; Cho, Wang, Nie, Chen, & Shin, 2008). Table 1 lists the advantages and disadvantages of the different nanotherapeutic carriers and eventually cites the needs for developing new nanosystem overcoming these cons. (Wicki, Witzigmann, Balasubramanian, & Huwyler, 2015).
Figure 1. An overview of FDA approved nanomedicines stratified by material category
Inorganic nanoparticles have shown a promising potential in drug delivery owing to their versatile physicochemical properties like easy and diverse availability, rich functionality, biocompatibility, controlled and targeted drug delivery, zero premature release and dual-drug delivery etc (Kim & Hyeon, 2014). Last decade has seen several type of inorganic nanoparticles including gold, silver, platinum, iron oxide, cerium oxide, zinc oxide and carbon derivatives.