Mesoporous silica nanoparticles (MSNs) provide a non-invasive and biocompatible delivery platform for a broad range of applications in therapeutics, pharmaceuticals and diagnosis. The creation of smart, stimuli-responsive systems that respond to subtle changes in the local cellular environment are likely to yield long term solutions to many of the current drug/gene/DNA/RNA delivery problems. In addition, MSNs have proven to be promising supports for enzyme immobilisation, enabling the enzymes to retain their activity, affording them greater potential for wide applications in biocatalysis and energy. This review provides a comprehensive summary of the advances made in the last decade and a future outlook on possible applications of MSNs as nanocontainers for storage and delivery of biomolecules. We discuss some of the important factors affecting the adsorption and release of biomolecules in MSNs and review of the cytotoxicity aspects of such nanomaterials. The review also highlights some promising work on enzyme immobilisation using mesoporous silica nanoparticles.

Herein, we report a core-shell pH-responsive drug-carrier based on chitosan-coated mesoporous silica nanospheres. The efficient positively charged polymer (chitosan) coating is realized by the phosphoramidate covalent bonding between phosphonate groups on the surface of the mesoporous silica nanoparticles (MSNs) and amino groups on chitosan. A pH-responsive release of ibuprofen has been achieved by varying the shell structure of positively charged chitosan in the designed pH 4.0-7.4 solution. Under basic conditions, chitosan forms a gel like structure which is insoluble and hence prevents ibuprofen release at pH 7.4. When the pH is below its PI (6.3), the drug has been released due to protonation of the amino group on chitosan. These results imply that the chitosan coated-MSNs are promising platforms to construct pH-responsive controlled drug delivery systems.

Vaccines have been at the forefront of improving human health for over two centuries. The challenges faced in developing effective vaccines flow from complexities associated with the immune system and requirement of an efficient and safe adjuvant to induce a strong adaptive immune response. Development of an efficient vaccine formulation requires careful selection of a potent antigen, efficient adjuvant and route of delivery. Adjuvants are immunological agents that activate the antigen presenting cells (APCs) and elicit a strong immune response. In the past decade, the use of mesoporous silica nanoparticles (MSNs) has gained significant attention as potential delivery vehicles for various biomolecules. In this review, we aim to highlight the potential of MSNs as vaccine delivery vehicles and their ability to act as adjuvants. We have provided an overview on the latest progress on synthesis, adsorption and release kinetics and biocompatibility of MSNs as next generation antigen carriers and adjuvants. A comprehensive summary on the ability of MSNs to deliver antigens and elicit both humoral and cellular immune responses is provided. Finally, we give insight on fundamental challenges and some future prospects of these nanoparticles as adjuvants.

No abstract