New insights into natural protein Nano-Cages: Teragnostic applications

Drug-delivery technology based on the application of drug-carriers has been gradually evolved since 1950s. Thenceforth, different types of carriers including liposomes, soluble polymers, microspheres, conjugated proteins and nanoparticles have been introduced and optimized for better and safer delivery in medical cargoes. Researchers worldwide have been worked hard in order to enhance the efficacy of handing-out certain types of drugs to certain types of cells (the concept of targeted therapy) by improving the pharmacokinetics and bioavailability of the delivery systems. Many types of materials have been investigated in order to build deliveryvehicles in nano-scale (≤100 nm) including lipids, metals (gold, silver, iron, etc.), polysaccharides (for example chitosan), different types of polymeric substances and so on. Here, we are going to review the recent emerging protein nano-cages used for medication delivery and/or diagnostic applications. We will also introduce differentcategories of these protein nano-cages and then discuss their pros and cons in contrast to other delivery media. Nano protein-cages are classified in two main categories known as viral and non-viral particles. Ferritin and Hsp can be introduced as well-known examples of non-viral protein nano-particles whereas CCMV and SV40 can be mentioned as viral ones. Both types of nano protein-cages can be produced and designed by the means of genetic engineering and sufficient expression in a suitable host (in most cases E.coli). The expressed proteins will bepurified and undergo an assembly/disassembly process, by the application of some gentle environmental changes (such as pH changes), in the presence of absence of the drug to be delivered. Obviously, much more consideration should be applied for constructing viral protein nano-particles due to their hazards and complexity. The perfect and definite structure of nano protein-carriers, low toxicity, biodegradability, biocompatibility, low immunogenisity, ease of functionalization, opportunity of large scale production, water solubility, and… are theunique characteristics of nano protein-carriers in comparison to other delivery media such as gold nano-particles, lipid nano-particles and so on. Hence, although nano protein-carriers are in their infancy and have not been tested in clinical trials yet, definitely their characteristic features will lead to a vast demand on exploration of these structures and development of their biomedical applications in near future.

Keywords:

Nano protein-cages , Drug delivery , Carriers , Nanomedicines