Adhesive interactions between cells and biotinylated phospholipid vesicles in alginate: towards new responsive biomaterials.

Creating tissue-mimetic biomaterials able to deliver bioactive compounds after receipt of a remote and non-invasive trigger has so far proved to be challenging. The possible applications of such "smart" biomaterials are vast, ranging from subcutaneous drug delivery to tissue engineering. Self-assembled phospholipid vesicles (liposomes) have the ability to deliver both hydrophilic and hydrophobic drugs, and controlling interactions between functionalized vesicles and cells within biomaterials is an important step for targeted drug delivery to cells. We report an investigation of the interactions between thermally-sensitive and biotin-coated dipalmitoyl phosphatidylcholine vesicles and 3T3 fibroblast cells. The stability of these vesicles under physiological conditions was assessed and their interaction with the cell membranes of fibroblasts in media and alginate/fibronectin mixtures was studied. Stable vesicle-cell aggregates were formed in fluid matrices, and could be a model system for improving the delivery of remotely released drugs within vesicle-containing biomaterials.

Directly bonding antimicrobial peptide mimics to steel and the real world applications of these materials.

Despite increased sterilisation and education campaigns, hospital acquired infections have not been eradicated. Bacterial colonisation of frequent touch surfaces is key in the transmission of infection. Most current technologies cannot provide a material which can rapidly kill bacteria. Here we report a novel surface technology, which uses synthetic mimetics of human defensin proteins on a surface. The surface shows excellent antibacterial efficacy against Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus, Pseudomonas aeruginosa and Escherichia coli. Both microbiology laboratory tests and trials in hospital settings of this new antimicrobial material (AMS) showed >99% efficacy over a year in situ. It maintains its efficacy through accelerated ageing tests and has shown to kill bacteria far more rapidly (45 min) than the commercially available technologies (24 h).

Antimicrobial peptide coatings for hydroxyapatite: electrostatic and covalent attachment of antimicrobial peptides to surfaces.

The interface between implanted devices and their host tissue is complex and is often optimized for maximal integration and cell adhesion. However, this also gives a surface suitable for bacterial colonization. We have developed a novel method of modifying the surface at the material-tissue interface with an antimicrobial peptide (AMP) coating to allow cell attachment while inhibiting bacterial colonization. The technology reported here is a dual AMP coating. The dual coating consists of AMPs covalently bonded to the hydroxyapatite surface, followed by deposition of electrostatically bound AMPs. The dual approach gives an efficacious coating which is stable for over 12 months and can prevent colonization of the surface by both Gram-positive and Gram-negative bacteria.

Peptide aptamers: Novel coatings for orthopaedic implants.

Current processes for coating titanium implants with ceramics involve very high energy techniques with associated high cost and disadvantages such as heterogeneity of the coatings, phase transformations and inability to coat complex structures. In order to address the above problems, we propose a biomimetic hydroxyapatite coating process with the use of peptides that can bind both on titanium surfaces and hydroxyapatite. The peptides enabled homogeneous coating of a titanium surface with hydroxyapatite. The hydroxyapatite-peptide sandwich coating showed no adverse effects on cell number or collagen deposition. This makes the sandwich coated titanium a good candidate for titanium implants used in orthopaedics and dentistry.