Mechanized Silica Nanoparticles: A New Frontier in Theranostic Nanomedicine

Abstract

Conspectus Nanotechnology has been cited as a response to the most challenging issues facing society as a whole today. With nanoscale assemblies promising to improve on previously established therapeutic and diagnostic motifs, medicine stands to benefit significantly from advances in nanotechnology. To this end, the use of delivery platforms has attracted attention during the past decade, with researchers shifting their focus towards devising ways to deliver therapeutic and / or diagnostic agents, and away from developing new drug candidates. Metaphorically, the use of delivery platforms in medicine can be viewed as the “bow-and-arrow” approach, where the drugs are the arrows and the delivery vehicles are the bows. Even if one possesses the best arrows that money can buy, the arrows are not going to be useful if one does not have the appropriate bow to deliver the arrows to a desired location. The same can be said of drugs. Currently, a variety of strategies for delivering bioactive agents within living tissue exists. Dendrimers, polymers, micelles, vesicles, and nanoparticles have all been investigated for their use as possible delivery vehicles. With the growth of nanomedicine, one can then envisage the possibility in theranostic medicine of fabricating a vector that is capable of releasing simultaneously powerful therapeutics and diagnostic markers selectively to diseased tissue. In our design of new theranostic delivery systems, we have focused our attention on using mesoporous silica nanoparticles (SNPs). It is possible to store a payload of “cargo” molecules within such a robust platform that is stable to a wide range of chemical conditions. This stability allows SNPs to be functionalized with responsive mechanically interlocked molecules (MIMs) in the shape of bistable rotaxanes and psuedorotaxanes to yield mechanized silica nanoparticles (MSNPs). These MIMs can be designed in such a way that they either change shape or shed off some of their parts in response to a specific stimulus, allowing a theranostic payload to be released from the nanopores to a precise location at the most ideal time. In this Account, we chronicle the evolution of various MSNPs which came about as a result of our decade-long collaboration, and discuss advances that have been made in synthesizing novel hybrid mesoporous silica nanoparticles, and the various MIMs which have been attached to their surfaces. Recognizing the theranostics of the future, we aim to start moving out of the chemical domain and into the biological one, with some MSNPs already being subjected to biological testing.

pH-controlled Release System for Curcumin based on Functionalized Dendritic Mesoporous Silica Nanoparticles

“…DDSs can improve the bioavailability of poorly water-soluble drugs via preventing premature degradation and enhancing uptake, leading to maintain the desirable controlled drug release and reducing side effects by targeting medicine to specified places [1]. Since mesoporous silica nanoparticles (MSNs) have been reported as a drug delivery systems for the first time [2], they became widely popular inorganic nano-carriers in DDSs [3][4][5][6][7][8][9][10][11][12]. MSNs have several attractive properties including their straightforward synthesis, large surface area, porous structure, silanol-containing surface that lead to facile functionalization chemistry, chemical and mechanical stability, biocompatibility and low-toxicity [13][14][15].…”

Mesoporous carbon biomaterials

“…Biocompatible inorganic mesoporous materials have attracted great attention in biomedicine over the past decades [24][25][26][27][28]. The well-defined mesoporous structures with large surface area, high pore volume, and tunable pore sizes provide large reservoirs for guest molecules and show sustained drug-release profiles [29][30][31].…”

Mechanostereochemistry and the mechanical bond

“…This fact renders the memory volatile, and current efforts in the field are devoted to adjusting the relaxation kinetics in order to obtain nonvolatile memory devices by increasing the lifetime of the MSCC while searching for ways to increase the robustness of the devices. MIMs have also been proved (Cotí et al 2009;Ambrogio et al 2011;Li et al 2012) to be promising active components for drug delivery and controlled release purposes in the form of mechanized silica nanoparticles (MSNPs). The MSNPs are fabricated by incorporating stimulus-responsive MIMs, i.e.…”