Russell J. Crawford

Bacterial Interaction with Graphene Particles and Surfaces

Research into the properties and uses of graphene has rapidly expanded over the past decade. Indeed, prior to the seminal paper by Geim and Novoselov in 2004 [1] which eventually led to the 2009 Nobel Prize for physics, the potential of this material was relatively underappre‐ ciated. Graphene is a monolayer thick, two dimensional form of carbon atoms linked together in a hexagonal lattice. The sp2 hybridisation of all bonds across the sheet gives rise to its interesting and unique, physical, mechanical, thermal and electrical properties. Thus graphene can be considered to be a 2 dimensional form of its analogue graphite [2]. Importantly, the properties of graphene vary significantly to the bulk material graphite, particularly in terms of electron mobility, and these significant feature differences have driven research in fields as diverse as electronics, materials, energy, defence, security, water and health [3, 4].

Natural polymer biomaterials: advanced applications

Advanced applications of natural polymers, including chitosan, alginate, starch, collagen and gelatin, and their utilisation in the fabrication of tissue engineering matrices and drug delivery systems, are discussed. The structure, synthesis pathways and modifications of various classes of natural polymers, spanning biodegradable materials, biomaterials intended for long-term implantation, and those used for targeted drug delivery and highly specific imaging, are also considered.

1 – Introduction to biomaterials and implantable device design

: Replacement and regeneration of lost function or tissue with well-matched biomaterials remains an area of active research and development, driving demand for novel and improved biomaterials. The ever-increasing complexity and high degree of integration of additives in modern biomaterials have significantly expanded the scope of biomaterial applications, but this has also introduced novel challenges. In this chapter, implantable electronic devices are used to demonstrate key issues and challenges associated with the design of complex implantable systems.

6 – Cytotoxicity and biocompatibility of metallic biomaterials

: Metallic biomaterials have found a plethora of applications as medical devices. However, the long-term performance of these materials is highly dependent on their ability to withstand synergistic effects of corrosion and wear. Loss of surface integrity and subsequent leaching of metal ions and particles into the peri-implant environment may undermine biocompatibility of metallic implants, also potentially causing untimely loss of mechanical function and device failure. This chapter reviews key issues relating to cytotoxicity and biocompatibility.

Bacterial attachment response to nanostructured titanium surfaces

The effect of sub-nanometric surface roughness of Ti thin films surfaces on the attachment of two human pathogenic bacteria, Staphylococcus aureus CIP 65.8T and Pseudomonas aeruginosa ATCC 9027, was studied. A magnetron sputtering thin film deposition system was used to control the titanium thin film thicknesses of 3 nm, 12 nm and 150 nm on silicon wafers with corresponding surface roughness parameters of Rq 0.14 nm, 0.38 nm and 5.55 nm (1 μm × 1 μm scanning area). Analysis of bacterial retention profiles showed that the bacteria responded differently changes in the Ra and Rq (Ti thin film) surface roughness parameters of a less than 1 nm, with up to 2–3 times: more cells being retained on the surface, and elevated levels of extracellular polymeric substances being secreted on the Ti thin films, in particular on the surfaces with 0.14 nm (Rq) roughness.

Bioinert ceramic biomaterials: advanced applications

First-generation, inert ceramics exhibit excellent mechanical strength, corrosion and wear resistance. This chapter reviews the fundamental properties that make alumina, zirconia, titania and pyrolytic carbon the materials of choice for the production of numerous load-bearing implants. The shortcomings of these materials, namely their relative brittleness and limited ability to be integrated with soft and hard tissues in vivo, are also discussed as a limiting factor for their clinical application.

Advanced synthetic polymer biomaterials derived from organic sources

Abstract: Synthetic polymers offer several advantages over their natural counterparts, including improved chemical resistance, tunability of their properties and mechanical durability. In this chapter, the properties and synthesis of several types of synthetic materials derived from organic polymers are reviewed. The use of these well-defined, highly ordered aggregates, as organised systems for bioactive molecule delivery as templates for the synthesis of metal nanoparticles and as micro-patterned scaffolds for directed attachment and growth of aligned cell monolayers, is discussed.

4 – Advanced synthetic and hybrid polymer biomaterials derived from inorganic and mixed organic–inorganic sources

: Polymeric biomaterials derived from inorganic and organo-metallic precursors promise to overcome the drawbacks associated with organic polymers. Their versatile chemistry, excellent physico-chemical and biological properties, and ability to undergo controlled biodegradation render them highly suited for a host of medical applications, from transient implants to drug and biomolecular delivery vehicles. In this chapter, inorganic, organic–inorganic hybrid and organo-metallic polymers are reviewed. Biomaterials are discussed in terms of their salient and impeding properties, and their likely role in present and future biomedical devices and treatments.

8 – Advanced bioactive and biodegradable ceramic biomaterials

: Bioinert high-strength ceramics have been shown to be suitable for load-bearing applications. Bioactive ceramics capable of forming direct chemical bonds with hard and soft tissues have been the ceramics traditionally used for most medical implantation devices. Recently, bioresorbable ceramics that actively participate in the metabolic processes of an organism into which they are implanted are attracting greater levels of attention. This chapter discusses ceramics that can not only physically mimic the osseous tissue but also competently initiate the biological processes associated with osteogenesis. Their ability to deliver biological and chemical molecules and then safely disintegrate within the body extend their clinical utility from tissue regeneration to highly controlled drug and vaccine delivery and in vivo visualisation.