Mesoporous means a particle having pores of size ranging from 2 nm – 50 nm. Mesoporous silica nanoparticles (MSNs) are finding increasing uses in drug, gene delivery, bio-imaging and tissue generation. Both in vitro and in vivo analysis shows that these particles cause no toxicity that is why they are of great importance for biotechnological advancement.
Method for the synthesis of silica nanoparticles was developed by scientist Werner Stober that is why it is called Stober method. Sol-gel process is widely used to synthesize silica nanoparticles. As the name sol-gel indicates it is the formation of sol and its transition into gel. Hydrolysis and condensation reactions result into gel formation. Tetraethylorthosilicate and alkyltrialkoxysilanes are the widely used precursors for silica sol–gel. Synthesis of sol-gel follows three steps: First hydrolysis of silica using tetraethylorthosilicate. Second steps is condensation of silica to form larger silica molecules called sol. Now the sol will be cross linked to form gel. Crosslinking involves polycondensation. Dry this gel to get powdered MSNs.
Mesoporous silica nanoparticles are capped with gate keeper molecules like cadmium sulfide so that entrapped molecule vancomycin (antimicrobial drug) cannot escape out from MSNs and reach safely at target cells with greater efficiency.
Cadmium disulfide form disulfide bridges with guest molecule vancomycin then these nanoparticles target cells. Target cells by the process of endocytosis or by carrier proteins incorporate MSNs within the cell. When MSNs find their target site then reducing agents such as DTT and mercaptoethanol are added to degrade gate keeper molecules and drug incorporate at target site.
Pros and Cons
MSNs have great surface area and controlled pore size due to which homogenous distribution of drugs or gene of interest occur within the MSNs. These nanoparticles are biocompatible with the cells and are found to be non-toxic.
However, a group of scientists have also observed their harmful aspects on cells but they are less common. Sometimes silanol, functional group of silica, may interact with the phospholipids of cell membrane and cause breakdown of cell membrane and as a result all the contents of cells may leak out.
Futuristic Approach for MSNs
Scientists are trying to use MSNs in biosensors. It is reported that as MSNs are transparent so scientists can incorporate biosensors within these MSNs. When these MSNs reach their target site light will emit due to fluorescent labeled biosensors. Hence it will aid in diagnosis of different diseases and especially in the field of oncology.
In genetic engineering for the production of transgenic animals and transgenic plants MSNs are employed for targeted and efficient delivery of genes within the cell. Therefore scientists are trying to design MSNs with greater biocompatibility.
MSNs are proved to be a very valuable tool for gene and drug delivery, for diagnostic and therapeutic applications in the field of research and pharmaceutical industry. Scientists are also trying to introduce MSNs for in-vivo applications and the results obtained are exciting. But some milestones are still need to be covered for further advancements.