Antiseptics for treating infected wounds: Efficacy on biofilms and effect of pH.

Biofilm recalcitrance is a persistent problem when managing difficult to heal and infected chronic wounds. The wound biofilm is a fundamental factor in the re-occurrence and delayed healing commonly observed in non-healing and infected chronic wounds. However, there is presently no single antimicrobial agent that is completely efficacious against both the planktonic and sessile polymicrobial communities evident in at risk or infected wounds. We will review currently available antimicrobials, with particular emphasis on silver and iodine, employed to help suppress biofilms in wounds. In addition, we will also review the effect of pH on antimicrobial efficacy. Available evidence suggests that it is best to take a multifactorial approach towards controlling biofilm in chronic, "at risk" and infected wounds. This highlights the growing importance of avoiding indiscriminate or inappropriate use of antimicrobials in the treatment of chronic wounds.

Nerve guides manufactured from photocurable polymers to aid peripheral nerve repair.

The peripheral nervous system has a limited innate capacity for self-repair following injury, and surgical intervention is often required. For injuries greater than a few millimeters autografting is standard practice although it is associated with donor site morbidity and is limited in its availability. Because of this, nerve guidance conduits (NGCs) can be viewed as an advantageous alternative, but currently have limited efficacy for short and large injury gaps in comparison to autograft. Current commercially available NGC designs rely on existing regulatory approved materials and traditional production methods, limiting improvement of their design. The aim of this study was to establish a novel method for NGC manufacture using a custom built laser-based microstereolithography (µSL) setup that incorporated a 405 nm laser source to produce 3D constructs with ∼ 50 µm resolution from a photocurable poly(ethylene glycol) resin. These were evaluated by SEM, in vitro neuronal, Schwann and dorsal root ganglion culture and in vivo using a thy-1-YFP-H mouse common fibular nerve injury model. NGCs with dimensions of 1 mm internal diameter × 5 mm length with a wall thickness of 250 µm were fabricated and capable of supporting re-innervation across a 3 mm injury gap after 21 days, with results close to that of an autograft control. The study provides a technology platform for the rapid microfabrication of biocompatible materials, a novel method for in vivo evaluation, and a benchmark for future development in more advanced NGC designs, biodegradable and larger device sizes, and longer-term implantation studies.

Complete ozonolysis of alkyl substituted ethenes at -60 degrees C: distributions of ozonide and oligomeric products.

The distribution of ozonide and oligomeric structures formed on complete ozonolysis of alkenes in a non-participating solvent at -60 degrees C is governed by the alkyl substitution around the carbon-carbon double bond. The ozonolysis of a 1,1-alkyl substituted ethene generally favours the formation of an ozonide (a 1,2,4-trioxolane). Whereas the ozonolysis of a 1,1,2-alkyl substituted ethene also produces ozonide, a considerable amount of the ozonised products are oligomeric in nature. For example, the ozonolysis of 3-methylpent-2-ene in solution to high conversion in pentane yields oligomers with structural units derived from the fragmentation products of the primary ozonide (a 1,2,3-trioxolane) which are namely butanone carbonyl oxide and acetaldehyde; these can be characterised by electrospray ionisation mass spectroscopy (ESI-MS) under soft ionisation conditions. The predominant oligomers formed are rich in carbonyl oxide units (80 + mol%) and are cyclic in nature. A small proportion of the oligomers formed are open chain compounds with end groups that suggest that chain termination is brought about either by water or by hydrogen peroxide. Residual water in the solvent will react with the carbonyl oxides to produce 2-methoxybut-2-yl hydroperoxide, which we propose readily decomposes generating hydrogen peroxide. A significant yield of oligomers also is obtained from the ozonolysis of a 1,2-alkyl substituted ethene. The ozonolysis of trans-hex-2-ene in pentane yields oligomers containing up to four structural units and are predicted to be mainly cyclic.

Ozonolysis of tetramethylethylene: characterization of cyclic and open-chain oligoperoxidic products.

The ozonolysis of tetramethylethylene (TME) in solution to high conversion in nonparticipating solvents at -60 degrees C yields predominantly oligoperoxides. For the first time, these products have been characterized using electrospray ionization mass spectrometry (ESI-MS) under soft ionization conditions. The predominant structure formed in reactions carried out in pentane (up to 2.0 M TME) is shown to be the cyclic hexamer of acetone carbonyl oxide (oligocarbonyl oxide with degree of polymerization, n = 6), but cyclic structures with n up to 19 are observed. A small proportion of the oligoperoxides formed are open-chain compounds with end groups that suggest that chain termination of oligocarbonyl oxides can occur through reaction with either water or hydrogen peroxide. Ozonolysis in dried butyl acetate similarly produces mainly cyclic oligoperoxides. However, ozonolyses carried out in undried butyl acetate yield mainly open-chain oligoperoxides, confirming that propagating carbonyl oxide chains are readily terminated by water. Relative amounts of the open-chain oligomers so-formed suggest that undried butyl acetate contains ca. 0.1% w/w water. The ozonolysis of TME in the participating solvent, methanol, at -60 degrees C yields 2-methoxyprop-2-yl hydroperoxide via reaction of acetone carbonyl oxide with methanol; no oligoperoxidic products are formed in this case.