Disulfide‐Bridged Organosilica Frameworks: Designed, Synthesis, Redox‐Triggered Biodegradation, and Nanobiomedical Applications

Abstract

Over the past few years, silica‐based nanotheranostics have demonstrated their great potential for nano/biomedical applications. However, the uncontrollable and difficult degradability of their pure silica framework and long‐time in vivo retention still cause severe and unpredictable toxicity risks. Therefore, it is highly desirable to design and synthesize materials with safer framework structures and compositions. To this aim, the introduction of disulfide bonds into the silica framework can not only maintain high stability in physiological conditions, but also achieve a stimuli‐responsive biodegradation triggered by intracellular reducing microenvironment in living cells, especially in cancer cells. Once nanotheranostics with disulfide (i.e., thioether)‐bridged silsesquioxane framework are taken up by tumor cells via passive or active targeting, the disulfide bonds in the hybrid silica matrix can be cleaved by a high concentration of intracellular glutathione, enabling redox‐triggered biodegradation of the nanosystems for both concomitant release of the loaded therapeutic cargo and in vivo clearance. It is envisioned that such hybrid materials comprised of disulfide‐bridged silsesquioxane frameworks can become promising responsive and biodegradable nanotheranostics. This review summarizes the recent advances in the synthesis of hybrid organosilicas with disulfide‐bridged silsesquioxane frameworks, and discuss their redox‐triggered biodegradation behaviors combined with their biocompatibility and nanobiomedical applications.

A Multifunctional Biodegradable Nanocomposite for Cancer Theranostics

“…Sci. [7,10,12,18] After 24 h, the mice were euthanized and ex vivo fluorescence imaging was performed on the major organs (heart, liver, spleen, lung, and kidney) and tumor tissue (Figure 6g). The area under the curve (AUC) of ICG/PFP@HMOP-PEG was distinctly greater than the AUC for the other two formulations (Table S1, Supporting Information).…”

“…[4,5] Particular interest has been placed on the use of nanomaterials in this regard, as a result of their ability to enter and accumulate in tumor cells; nanoscale theranostics can thus significantly improve diagnostic or/ and therapeutic efficacy. [10,11] Various organic moieties can be incorporated into MONs, and since these are intrinsic components of the framework they do not block the pore channels. [7][8][9] The latter are similar to mesoporous silicas, but rather than comprising pure SiO 2 contain organic functional groups within the silica framework.…”

Biodegradable Periodic Mesoporous Organosilica (BPMO) Loaded with Daunorubicin: A Promising Nanoparticle‐Based Anticancer Drug

“…Advance in Nanotechnology led to the development of a variety of nanoparticle based anticancer drugs. Biodegradable periodic mesoporous organosilica (BPMO) nanoparticles represent a new class of mesoporous silica nanomaterials (MSN) that have attracted considerable attention as a promising vehicle in drug delivery . While MSN are synthesized by classical sol‐gel reaction of tetraethyl orthosilicate (TEOS), BPMO use bridged organosilane precursors that enable homogeneous and covalent incorporation of organic moieties.…”

“…Biodegradable periodic mesoporous organosilica (BPMO) nanoparticles represent a new class of mesoporous silica nanomaterials (MSN) that have attracted considerable attention as a promising vehicle in drug delivery. [1][2][3][4][5] While MSN are synthesized by classical sol-gel reaction of tetraethyl orthosilicate (TEOS), BPMO use bridged organosilane precursors that enable homogeneous and covalent incorporation of organic moieties. In particular, this approach results in the uniform distribution of biodegradable bonds into the silylated framework.…”

In Situ Synthesis of Fluorescent Mesoporous Silica–Carbon Dot Nanohybrids Featuring Folate Receptor-Overexpressing Cancer Cell Targeting and Drug Delivery

“…Among various nanomaterial-based DDSs, mesoporous silica nanoparticles (MSNs) have been well demonstrated as excellent carriers for intracellular drug delivery owing to their unique properties, including mesoporous structure, large specific surface area, and pore volume, as well as high biochemical and physicochemical stability, facile surface functionalization, and excellent biocompatibility in particular [19][20][21][22]. To further improve their therapeutic efficacy, endowing the DDSs with diagnostic and targeting capabilities has recently been an important issue [23][24][25][26].…”