Nanoparticle Delivery Biofactory Using E. coli as the Synthetic Host

Nanoparticles exhibit unique physical, mechanical, optical and electromagnetic properties owing to the increase in surface area to volume ratio as compared to the bulk material. The unique characteristics pave ways to a wide array of applications such as detection of proteins, tumor destruction, tissue engineering and MRI contrast enhancement. Biological synthesis of these nanoparticles using bacterial hosts is being explored as an alternative to chemical synthesis as it is environmentally friendly. Protein nanocages, when employed as templates facilitate production of size controlled, monodispersed nanoparticles. Bacterial hosts harboring these protein nanocages could be engineered with surface ligands for tissue-specific accumulation for enhanced imaging in MRI applications.

Archaeoglobus fulgidus Ferritin (AfFtn) a self-assembling, 24-subunit iron storage protein which maintains iron homeostasis, is used as a template for iron nanoparticle synthesis in E. coli. To enhance iron uptake and reduce iron efflux, E. coli has been further engineered to express iron influx transporter protein (feoB) while knocking out iron efflux protein (ΔfieF). In vivo iron loading in AfFtn was achieved by incubating E. coli with excess iron in the growth medium. The iron loaded host is further targeted towards colorectal cancer cells for nanoparticle delivery.