The mechanism of spontaneous assembly of microscale compartments is a central question for the origin of life, and has technological repercussions in diverse areas such as materials science, catalysis, biotechnology and biomedicine. Such compartments need to be semipermeable, structurally robust and capable of housing assemblages of functional components for internalized chemical transformations. In principle, proteins should be ideal building blocks for the construction of membrane-bound compartments but protein vesicles with cell-like properties are extremely rare. Here we present an approach to the interfacial assembly of protein-based micro-compartments (proteinosomes) that are delineated by a semi-permeable, stimulus-responsive, enzymatically active, elastic membrane consisting of a closely packed monolayer of conjugated protein-polymer building blocks. The proteinosomes can be dispersed in oil or water, thermally cycled to temperatures of 70°C, and partially dried and re-inflated without loss of structural integrity. As a consequence, they exhibit protocellular properties such as guest molecule encapsulation, selective permeability, gene-directed protein synthesis and membrane-gated internalized enzyme catalysis.

Figure 2. Vesicle sizes achieved by different kinds of film rehydration, controlled and uncontrolled and also using electroformation. 62 Electroformation itself is shown on the left where dome-like structures evolve with PEG−PDEA. 66 (Part (a) reproduced with permission from ref 62. Copyright (2009) Nature Publishing Group).Figure 3. Possible structures observed when using a pH guided assembly of poly((butyl)methacrylate)−poly(methacrylic acid) PBMA−PMA via 2 pathways of vesicle creation (VC1 and VC2) and the final creation of spheres (CS1 and CS2). 68 (Reproduced with permission from ref 68. Copyright (2009) Royal Society of Chemistry).

A dual-targeting drug delivery and pH-sensitive controlled release system based on multifunctionalized graphene oxide (GO) was established in order to enhance the effect of targeted drug delivery and realize intelligently controlled release. A superparamagnetic GO-Fe 3 O 4 nanohybrid was firstly prepared via a simple and effective chemical precipitation method. Then folic acid, a targeting agent toward some tumor cells, was conjugated onto Fe 3 O 4 nanoparticles via the chemical linkage with amino groups of the 3-aminopropyl triethoxysilane (APS) modified superparamagnetic GO-Fe 3 O 4 nanohybrid, to give the multi-functionalized GO. Doxorubicin hydrochloride (Dox) as an anti-tumor drug model was loaded onto the surface of this multi-functionalized GO via p-p stacking. The drug loading capacity of this multi-functionalized GO is as high as 0.387 mg mg À1 and the drug release depends strongly on pH values. Cell uptake studies were carried out using fluorescein isothiocyanate labeled or Dox loaded multi-functionalized GO to evaluate their targeted delivery property and toxicity to tumor cells. The results show that this multi-functionalized GO has potential applications for targeted delivery and the controlled release of anticancer drugs.

The design and construction of higher-order structure and function in proteinosome microcompartments enclosed by a cross-linked membrane of amphiphilic bovine serum albumin/poly(N-isopropylacrylamide) (BSA-NH2/PNIPAAm) nanoconjugates is described. Three structure/function relationships are investigated: (i) differential chemical cross-linking for the control of membrane disassembly and regulated release of encapsulated genetic polymers; (ii) enzyme-mediated hydrogel structuring of the internal microenvironment to increase mechanical robustness and generate a molecularly crowded reaction environment; and (iii) self-production of a membrane-enclosing outer hydrogel wall for generating protease-resistant forms of the protein-polymer protocells. Our results highlight the potential of integrating aspects of supramolecular and polymer chemistry into the design and construction of novel bioinspired microcompartments as a step toward small-scale materials systems based on synthetic cellularity.