Biofunctionalized Mesoporous Silica Nanomaterials for Targeted Drug Delivery

Pharmaceutical nanocarriers are rapidly developing toward “magic bullets” with highly specified target cells and tissues, as well as controlled release of therapeutic agents. However, several challenges remain unanswered, such as the premature release of the drugs, the adverse side effects, and the toxic degradation products or nanoparticle accumulation in the organs. As one of the most interesting nanoplatforms, mesoporous silica nanoparticles (MSNs) feature as promising drug delivery platforms with a great capability to highly specialized functionalization and tunability. The diameter and shape of the particles, in tandem with the size and connectivity of the mesopores, can be controlled in a precise fashion during the fabrication process. The surface chemistry can also be tuned to allow for conjugation of functional molecules, such as prodrugs, targeting molecules, or responsive polymers for controlled drug release, as well as for controlling the surface charge according to the requirements of the application. High surface area allows loading diverse amounts of drugs, while the expandable pore size facilitates also the loading of larger therapeutic agents, such as proteins and DNA. Furthermore, silica biodegrades into silicic acid, which is nontoxic and is rapidly excreted via the urinary pathway. MSNs have been demonstrated to have potential applications as multifunctional delivery platforms with targeted delivery, controlled release, and theranostics, a few of which will be highlighted in this review.