The oral cavity is colonised by a whole community of microbes that include bacteria, viruses and fungi. The ecology or interrelationships between the members of the various microbial communities are highly intricate and under constant investigation with new links in the network being uncovered regularly. It is thought that changes in community structure invoke degenerative diseases that cause tissue destruction of dentine, periodontal ligament, gingiva and bone. Once the environment and conditions favour the acceleration of pathogenic growth the disease and tissue destruction is highly likely to occur. Effective ways must be sought to control and eradicate pathogenic microbes from the mouth. A degree of control is often required to reset the community structure of bacteria. There has been voluminous research to effectively kill pathogenic outright. Antibiotics are the most effective altogether. However, there is increasing evolved resistance to antibiotics and the targeted delivery of antibiotics remains imperfect. Other main treatments implement chemical toxins, photodynamic elements and nanoparticles to destroy bacterial biofilms and kill bacteria. There is also renewed interest in prospecting for new antibacterial compounds from sessile invertebrates renowned for the complex defensive chemistry, e.g. Marine sponges and Ascidians. As such there are many examples in nature where evolution has selected for sophisticated adaptations to kill microbes or prevent contact with the organism. A significant adaptation that has emerged is structural devices at surfaces.

Nature has evolved countless interfaces precisely with anti-bacterial defences using specific Nano topographies alone. And this is independent of the effects from chemical secretions. Probably the first application of patterned surfaces of diamond shaped micro-protuberances to hinder bacterial contamination is Sharklet inspired from the micron structure of scales or dermal denticles from shark-skin [16, 17]. The synthetically replicated surface hinders growth of a range of biomedically significant bacteria species such as, Staphylococcus aureus and Escherichia coli [16, 17]. The special nanostructure at the surface are deleterious to Pseudomonas aeruginosa and lead to the shredding of other pathogenic species including: B. catarrhalis, E. coli, P. aeruginosa, and P. fluorescens. Another recently discovered bactericidal surface imported directly from nature is the Cicada wing surface (Fig. 11.2).

The structure consists of nanometric pillars 200 nm tall, 100 nm in diameter at the base and 60 nm at the tip spaced 170 nm apart in a highly regular and tight pattern. This precision piece of Nano architecture being ten times smaller than the cell itself punctured settling bacterial cells and killed them with 60 min from attachment (Fig. 11.2). The killing power has been measured for this wing surface and was described as being efficient with 6 × 10⁶ bacterial cells made inoperable in every square centimeter after 30 min [18]. These initial results represent are of supreme usefulness for control of clinical infections anchored onto biomaterial and implant surfaces. However, the topography did not kill gram-positive species of bacteria: B. subtilis, P. maritimus, and S. aureus species of bacteria. Other wing topographies are being actively pursued as potential antibacterial and bactericidal devices. It has been reported that Dragonfly wings Diplacodes bipunctata have strong and rapid bactericidal effects on a broader range of bacteria classes-both gram negative and gram-positive types as well as bacterial spores. A synthetically created surface with the exact same features of densely packed protruding nanospikes as the Dragonfly wing demonstrated the same bactericidal effects. It was estimated that 45,000 bacterial cells every minute in every cm squared were killed. Black silicon is this equivalent and is generated using ion beam technology. This is costly and cannot be transferred onto just any surface and specifically onto the type of materials useful in biomedicine [19].

Surface roughness and structure influences human cells more acutely than bacterial cells. This is because eukaryotic cells have a much more complicated sensory apparatus than prokaryotes. It was first evidenced that human cells can sense, detect and “react” to structures of >5 nm at very small distances of 3–15 nm [20]. Physical attachments between cells and extracellular matrix (ECM) molecules can only be made at such close distance. There is broad remit to harness the sensory apparatus of the cell and influence their behaviour in many important aspects such as, migration, alignment, polarity, differentiation and proliferation. Such governability opens up many biotechnological and therapeutic avenues from tissue regeneration to biosensing.