This talk will be of considerable relevance to the SUPA initiatives in Bio-nanophotonics.
Diabetes is a serious word health problem. Opportunities for applications of nanomedicine in diabetes are numerous.
In type 1 diabetes, improved insulin replacement is urgently needed, but transplantation of islet cells is not routine, limited by availability of human islets and poor post-transplant islet survival. Nano-encapsulation might protect islets from early cell death caused by the inflammatory in vivo environment and isolate against later immune rejection. We found allogeneic transplantation of mouse islets encapsulated with nanofilms made by layer-by-layer application of polysaccharides improved survival compared to naked islets, when transplanted into diabetic animals. In type 2 diabetes, early introduction of insulin is often resisted by patients; we are researching nano-formulations of oral insulin, where layer-by-layer nano-encapsulation of the protein may produce a more patient-acceptable formulation.
In both types of diabetes, more stable and accurate continuous glucose monitoring is needed. We are researching fluorescence intensity and nanosecond lifetime photonics as a glucose detection technology. Mutants of glucose/galactose-binding protein (GBP) have been engineered and labelled with the environmentally sensitive fluorophore, badan. Glucose binding causes conformational change in the GBP and increased fluorescence lifetime and intensity. Prototype fibre-optic glucose sensors for subcutaneous implantation, based on GBP, have been constructed and tested. GBP containing vesicles with nanothickness membranes have been fabricated as a ‘smart tattoo’-type of sensor. We found that Blue oxazine is an environmentally sensitive fluorophore in the near-infrared region and attached it to GBP using click chemistry. This might be particularly suitable for non-invasive glucose sensing.