Nanotechnology promises to make medicines better by enhancing control over their physical and biological properties, including cell selectivity.[1] Liposome nanocarriers and nanoparticles represent well-studied platforms for cell-specific delivery both in vitro and in vivo.[2] These systems can encode complex functionality, for example immune targeting and immune evasion, but often suffer from a lack of stability, limited cargo capacity, cellular processing through non-functional pathways, or a general loss of intended function simply due to the complexity of the in vivo environment.[3] At the other end of the drug delivery spectrum, emulsions and nanoemulsions have alreday found widespread use in clinical medicine but, in most cases, do not encode sophisticated function, for example the ability to specifically target a given cell population in vivo.[4] This limitation arises from the difficulty of engineering the emulsion interface, which is usually populated by mixed chemical species including surfactants, and is less physically and chemically defined than the solid counterpart. A nanoemulsion able to evade immune clearance to specifically target a sub-population of cells in vivo via a chosen receptor has not, to the best of our knowledge, been reported. Here we report a new method for assembling a molecularly defined nano-sized oil-in-water emulsion that is able to target dendritic cells (DC) in a receptor-specific fashion to activate a specific T-cell response. Our approach employs non-covalent click self-assembly, building an emulsion from the interface up using top-down sequential reagent addition. The nanoemulsion is formed using recently-reported molecular approaches for emulsion interface design and stabilisation, and relies on mixing closely-matched designer biosurfactant peptides and proteins at the oil-water interface. By conjugating immune-evading poly-ethylene glycol (PEG) or receptor-specific antibody elements with biosurfactant protein, we show it is possible to present and tune the presence and function of the elements at the interface by simple ratioed sequential addition of reagents to the self-assembling mixture. In this work, intraperitoneal administration of an optimised nanoemulsion to mice confirmed specific uptake by the subset of DCs targeted by an anti-Clec9A monoclonal antibody, a receptor understood to facilitate enhanced CD8+ T cell mediated vaccine responses as would be required for anti-viral or anti-tumor immunity.[5] This work introduces a new class of targeted and immune-evading nanocarrier made using only biological components and facile processes, assembled in a bottom-up fashion through simple top-down sequential reagent addition.

A tailorable nano-sized emulsion (TNE) formed by sequential reagent addition has recently been shown to effectively co-deliver curcumin and antigen to cells in vitro.[6] The reported TNE comprised a core that is a pharmaceutical-grade oil stabilized by a surface-active designer peptide AM1,[7] rendered stable in physiological conditions by electrostatic deposition of the antigen of interest onto the TNE outer surface. However, this approach requires that the cargo antigen perform both a biological (antigenic) and physical (emulsion stabilization) role, and limits scope for further nano-engineering of the TNE surface (eg for cell targeting). Here we decouple the biological and physical design criteria through a novel emulsion nano-engineering approach. Inspired by the chemical similarity of a recently-reported protein biosurfactant DAMP4 and its recently-determined mixing behaviour with a small peptide surfactant closely related to AM1,[8] we hypothesized that DAMP4 would integrate into …