Gated Materials for On-Command Release of Guest Molecules

Abstract

Multidisciplinary research at the forefront of the field of hybrid materials has paved the way to the development of endless examples of smart devices. One appealing concept in this fertile field is related to the design of gated materials. These are constructed for finely tuning the delivery of chemical or biochemical species from voids of porous supports to a solution in response to predefined stimuli. Such gated materials are composed mainly of two subunits: (i) a porous inorganic support in which a cargo is loaded and (ii) certain molecular or supramolecular entities, generally grafted onto the external surface, which can control mass transport from pores. On the basis of this concept, a large number of imaginative examples have been developed. This review intends to be a comprehensive analysis of papers published until 2014 on hybrid mesoporous gated materials. The molecules used as gates, the opening mechanisms, and controlled release behavior are detailed. We hope this review will not only help researchers who work in this field but also may open the minds of related ones to develop new advances in this fertile research area.

Recent applications of the combination of mesoporous silica nanoparticles with nucleic acids: development of bioresponsive devices, carriers and sensors

“…For this reason a significant effort has been done to develop different responsive systems able to efficiently retain the loaded compounds. 10,17 Among all different nanogates developed, extensively reviewed by Martiñez-Máñez and coworkers, 17 our interest would be focused only on the use of nucleic acids, particularly DNA. The use of NAs for this purpose present significant advances as biocompatibility, custom synthesis, length variability and chemical stability, huge sensitivity towards complementary sequences, recognition abilities and gene modulation roles.…”

“…Although is consequence too of the development of advanced systems itself, which usually include non-evaluated chemical species to provide a better drug release profiles which may compromise the potential use of the generated devices. A good example of this effect could be found on the development of molecular gates for MSNs 16,17 whose laudable purpose of drug carriage of retention of therapeutic drugs could be medically limited by the extensive use of non-biogenic compounds of broad nature (polymers, sensitizers, linkers, cytotoxics, other nanoparticles, etc.). Moreover the incorporated sensitivity to a variety of stimuli (pH, temperature, glutathione, etc.)…”

“…Moreover the incorporated sensitivity to a variety of stimuli (pH, temperature, glutathione, etc.) 17 may lead in unexpected, remainder, potent and persistent side effects (accumulated xenotoxicity, enhanced sensitivity to components or uncontrolled physiological responses, etc.) Then, to avoid those issues, an important effort has been done by researchers to introduce biocompatible compounds to reduce the impact of those advanced MSNs based nanomedicines.…”

Stimuli-responsive hybrid nanocarriers developed by controllable integration of hyperbranched PEI with mesoporous silica nanoparticles for sustained intracellular siRNA delivery

“…17,18 Furthermore, MSNs may facilitate slow, sustained and controlled release 19 owing to their design flexibility that enables multifunctionality as well as allows for sequential release. 20 Consequently, a veritable explosion of research efforts has occurred in the area of siRNA delivery by MSNs.…”

Self‐Immolative Linkers as Caps for the Design of Gated Silica Mesoporous Supports

“…[4] In fact, through decoration of the mesoporous material with a wide collection of organic and biological entities or inorganic capping agents, researchers have prepared recently gated MSNs that can be triggered by target chemical (such as selected anions, cations neutral molecules, redox-active molecules, pH changes and biomolecules), physical (such as light, temperature, magnetic fields or ultrasounds) and biochemical (such as enzymes, antibodies, or DNA) stimuli. [5] From a different point of view, self-immolative molecules are covalent aggregates that, upon application of an external trigger, initiate a disassembly reaction, through a cascade of electronic elimination processes, leading ultimately to the release of its building blocks. [6] This chemical phenomenon is usually driven by a cooperative increase in entropy coupled with the irreversible formation of thermodynamically stable products.…”