6533b7d5fe1ef96bd1264267

RESEARCH PRODUCT

Highly tunable protein microspheres for drug delivery

subject

description

Traditionally protein aggregation has been related to several neurodegenerative diseases, however in the past few years there has been a grown interest to use them as biomaterials. Among the very broad range of different amyloid structures a special focus has been developed on protein particulates, spherical protein aggregates formed at a pH near the isoelectric point of the protein they are made of, whose radius ranges from hundreds of nm to few um. They are a generic feature for all globular proteins and besides, they have never been related to any disease. Among the years different methods for the functionalization of amyloid fibrils or microspheres have been unravelled, but normally they are very time consuming techniques due to the use of fusion proteins or a crosslinker. Here we present an experimental study in which alpha-lactalbumin (ALA) protein particulates were formed at different time points and at different concentration ranging from 1 to 40 mg/ml. Stability towards acidic pH was assayed and size distributions for protein particulates at different concentrations were measured. Finally, aggregation process was stopped to add labelled protein in a not fully matured state to finish maturation process. Raster Imaging Correlation Spectroscopy (RICS) shows that particulates incubated at different times have different resistance towards pH, as fully matured are resistant when subjected to pH 2 while half matured is completely destroyed. Besides, when particulates are incubated at higher concentrations they grow in size being able to control the radius of our particles. Finally confocal microscopy images show how when maturation is stopped to add labelled protein, this protein is located on the surface, allowing us to functionalize without any further crosslinking the surface of our microspheres. To sum up, we were able to form protein particulates and to probe their high tunability simply changing their conditions during their formation. In fact, we were able not only to form particulates with different stability but to smartly control their size and functionalize them without any other chemical compound as a crosslinker.