Synthetic tissue engineering with smart, cytomimetic protocells.

Synthetic protocells are rudimentary origin-of-life versions of natural cell counterparts. Protocells are widely engineered to advance efforts and useful accepted outcomes in synthetic biology, soft matter chemistry and bioinspired materials chemistry. Protocells in collective symbiosis generate synthetic proto-tissues that display unprecedented autonomy and yield advanced materials with desirable life-like features for smart multi-drug delivery, micro bioreactors, renewable fuel production, environmental clean-up, and medicine. Current levels of protocell and proto-tissue functionality and adaptivity are just sufficient to apply them in tissue engineering and regenerative medicine, where they animate biomaterials and increase therapeutic cell productivity. As of now, structural biomaterials for tissue engineering lack the properties of living biomaterials such as self-repair, stochasticity, cell synergy and the sequencing of molecular and cellular events. Future protocell-based biomaterials provide these core properties of living organisms, but excluding evolution. Most importantly, protocells are programmable for a broad array of cell functions and behaviors and collectively in consortia are tunable for multivariate functions. Inspired by upcoming designs of smart protocells, we review their developmental background and cover the most recently reported developments in this promising field of synthetic proto-biology. Our emphasis is on manufacturing proto-tissues for tissue engineering of organoids, stem cell niches and reprogramming and tissue formation through stages of embryonic development. We also highlight the exciting reported developments arising from fusing living cells and tissues, in a valuable hybrid symbiosis, with synthetic counterparts to bring about novel functions, and living tissue products for a new synthetic tissue engineering discipline.

High Quality Bioreplication of Intricate Nanostructures from a Fragile Gecko Skin Surface with Bactericidal Properties.

The external epithelial surfaces of plants and animals are frequently carpeted with small micro- and nanostructures, which broadens their adaptive capabilities in challenging physical habitats. Hairs and other shaped protuberances manage with excessive water, light contaminants, predators or parasites in innovative ways. We are interested in transferring these intricate architectures onto biomedical devices and daily-life surfaces. Such a project requires a very rapid and accurate small-scale fabrication process not involving lithography. In this study, we describe a simple benchtop biotemplating method using shed gecko lizard skin that generates duplicates that closely replicate the small nanotipped hairs (spinules) that cover the original skin. Synthetic replication of the spinule arrays in popular biomaterials closely matched the natural spinules in length. More significantly, the shape, curvature and nanotips of the synthetic arrays are virtually identical to the natural ones. Despite some small differences, the synthetic gecko skin surface resisted wetting and bacterial contamination at the same level as natural shed skin templates. Such synthetic gecko skin surfaces are excellent platforms to test for bacterial control in clinical settings. We envision testing the biocidal properties of the well-matched templates for fungal spores and viral resistance in biomedicine as well as co/multi-cultures.

The role of micro/nano channel structuring in repelling water on cuticle arrays of the lacewing.

Non-wetting surfaces help in the survival of terrestrial and semi-aquatic insects. Some insects encounter wetting by rain, through contact with water collected on foliage, or in ponds, rivers or streams. There is an evolutionary pay-off for such insects to adopt hydrophobic structuring especially on regions that contact water, such as legs or large surface areas such as wings. Here we investigate lacewings which are good candidates for getting trapped to water because of a large wing surface area-to-body mass ratio. The lacewing utilises a variety of structures/mechanisms to contend with water contact. The first level involves small hairs (macrotrichia) that project from veins on the wings and collectively hold up droplets of water above the wing surface. This defence against wetting is aided by longitudinal ridges and troughs along the hair shaft. We show, by coating single hairs with a hydrophobic polymer (similar in hydrophobicity to insect cuticle), that the channels significantly contribute to repel water droplets. Beneath the array of hairs lies a dense netting on the cuticle wing surface which reduces contact with smaller droplets. The study has implications for both insect biology and biomimetic surfaces such as light weight superhydrophobic materials.