SAGEs: Self-assembled peptide-based cages for the presentation, encapsulation and delivery of bioactive molecules to cells in culture

An ability to deliver biologically active molecules (drugs, DNA and proteins) to specified cells either in the lab or the body would impact on many branches of biology and medicine. Imagine being able to selectively find and destroy diseased cells; or "simply" to test the effectiveness of a new drug inside a range of cells before animal and human trials? Unfortunately, there is no general solution to this problem of delivering bioactive molecules within cells, and even bespoke true solutions are few and far between. The problem is not straightforward, and is best illustrated by how biology has evolved viruses to do this. Viruses are astonishing natural nanoscale packages, usually termed virions. Though they come in many types, all virions perform three functions: (1) they recognise often specific cell types, which they do by presenting molecules on their surfaces to recognize molecules on the target cells; (2) they penetrate the outer barriers of the cell; and (3) they deliver a payload, which is the genetic information to make more virus in the host cell. Functions (1) and (2) are performed by the viral coats, or capsids. Not surprisingly, many people have tried to mimic these structures to deliver payloads other than RNA and DNA. AIMS, OBJECTIVES AND ASPIRATIONS OF THE RESEARCH: The overall ambition of the proposed work is to produce hollow, cage-like particles that have the diameter of about one hundredth the width of a human hair, so-called SAGE particles. We will do this in a modular way, using small versions of proteins called peptides. Each peptide module will have a specific function to mimic one the properties of virions: one set will be made to recognize specific cell types; another will be used to construct the casing of the particles; and the third set will carry the biologically active payloads. On their own, these modules would not be useful at all. However, if combined correctly they could assemble into virus-like particles, but without the (deadly) RNA and DNA cargo, instead they would contain drugs or useful proteins. To do this we will build on a multidisciplinary team of chemists, biochemists, cell biologists and molecular modellers that has delivered the SAGE particles. The physical scientists will work together to design and make the assemblies of molecules, and then work with the biologists to test and visualise how they interact with cells and deliver their payloads