Hollow Mesoporous Functional Hybrid Materials: Fascinating Platforms for Advanced Applications

Abstract

Functionalized hollow nano-and microspheres containing both hollow and mesoporous structures are fascinating materials for a broad range of applications, such as nanoparticle collectors, catalysis, drug delivery systems, immobilization of biomolecules, and the adsorption and separation of gas and pollutants, because of their empty interior. These hollow mesoporous silica materials are synthesized mainly via soft-and hard-templating routes and are usually modified with a range of organic functional groups (SH, NH 2 , CN, CH 3 , CC, benzene, fluorine linked organoalkylsilanes, and ethane-, amine, benzene, and biphenyl-bridged silanes) to improve their performance in many applications. This article outlines the most advanced applications of silica-based and functionalized hollow mesoporous materials that are reported in the last 3 years (January 2014-June 2017). The high applicability of hollow materials in various fields is discussed, including drug delivery and cancer therapy, bioimaging, adsorption/separation, catalysis, thermal and electrical insulators, anticorrosion, sensors, fuel cells, proton conductors, membrane, optics, superhydrophobic surfaces, and fire safety.

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

“…In particular, mobile composition of matter (MCM)‐41‐type mesoporous silica powder was first employed as a drug (ibuprofen) carrier in 2001 and demonstrated an interesting sustained release behavior in aqueous solution . Since then, mesoporous silica nanoparticles/nanospheres (MSNs) have been considered as one of the most promising platforms for modern drug delivery systems owing to their well‐defined mesopores with various pore sizes and structures for efficient drug loading, their high stability under physiological conditions, the possibility of easy and versatile functionalization, and suitable biocompatibility . In order to adjust the pharmacokinetic profile, reduce off‐target toxicity, and improve therapeutic and diagnostic efficacy/index, many silica‐based delivery and/or imaging nanosystems exhibiting stimuli (pH, redox potential, enzyme, light, thermal, etc.…”

“…)‐responsive release and active targeting properties (by introduction of a variety of ligands such as antibodies, aptamers, and peptides) have been developed . The study of silica‐based nanocarriers or nanoprobes has gradually evolved initially from investigations in solutions to cells, then to animal level (e.g., mice), and finally to preclinical stage . Excitingly, a type of multimodal small (size: 5–7 nm) nonporous silica nanoparticles (NPs) (also known as Cornell Dots (C‐Dots)) was approved by the U.S. Food and Drug Administration (FDA) in 2011 for the “first‐in‐human” clinical trial for target diagnostics of advanced melanoma due to specific tumor targeting imaging and efficient renal clearance .…”

“…Successful translation of MSN‐based nanosystems from laboratory research to clinical application requires comprehensive and systematic studies in the area of in vivo nanobiomedical applications. Although many designed silica‐based nanosystems/formulations exhibit superior therapeutic efficacy in small animal models, uncontrolled degradability of silica framework and long‐term in vivo retention still cause potential risks . Therefore, their biosafety has to be investigated at different levels from the molecule, cell, blood, tissue, and finally, to animal, before preclinical and clinical trials in the near future.…”

“…Therefore, their biosafety has to be investigated at different levels from the molecule, cell, blood, tissue, and finally, to animal, before preclinical and clinical trials in the near future. The study of the biosafety, including cytotoxicity, hemocompatibility, blood circulation, biodistribution, tissue penetration, in vivo toxic side effects, immune response, excretion, and biodegradability, has recently attracted increasing attention …”

Removal of Cr(VI) from Aqueous Solution by Polypyrrole/Hollow Mesoporous Silica Particles

“…Therefore, the adsorption effect of PPy for Cr(VI) can be substantially improved by solving the agglomeration issues. To this end, our attention has been focused on hollow mesoporous materials composed of hollow cavities and mesoporous shells of various sizes, because those larger specific surface areas, lower densities, and higher permeability offer great potential as adsorption materials [14,15].…”