Protein Cages as Responsive Tools for Nanomedicine

Different types of protein cages are nowadays studied in the fields of nano- and materials science, because of their well-defined size and structure in the nanometer regime. Compared to more traditional polymer-based nanoparticles, these – often – virus-based materials are extremely uniform, and the position of functional groups is precisely defined. Encapsulins are protein cages found in bacteria that have interesting properties with respect to (thermal) stability and cargo loading. In the past we and others have studied the application of encapsulins, but so far, their preparation, durability and functionalization are restricted to fundamental studies.¹<br/>Recently, we reported the design of encapsulins from two different origins (e.g., <i>T. maritima</i> and <i>B. linens</i>) with functional loops on its surface.² This allows for future site specific genetic or chemical modification. We, furthermore, optimized the cages’ production and showed that, under the selected conditions, these are stable over time periods of a least a year. Both the genetic and chemical manipulation of the encapsulin based protein cages allows for the introduciton of functional compounds, such as fluoresecent proteins for recognition of enzymes for therapeutic applications. Exciting new developments are the introduction of moieties that respond to an external trigger, where promising results are obtained with - amongst others - light responsiveness. <br/>The research presented in the contribution, therefore, paves the way for further design, engineering and production of encapsulins, for instance for drug delivery, vaccine development or other theranostic applications.