A collagen-based layered chronic wound biofilm model for testing antimicrobial wound products

A new in vitro chronic wound biofilm model was recently published, which provided a layered scaffold simulating mammalian tissue composition on which topical wound care products could be tested. In this paper, we updated the model even further to mimic the dynamic influx of nutrients from below as is the case in a chronic wound. The modified in vitro model was created using collagen instead of agar as the main matrix component and contained both Staphylococcus aureus and Pseudomonas aeruginosa. The model was cast in transwell inserts and then placed in wound simulating media, which allowed for an exchange of nutrients and waste products across a filter. Three potential wound care products and chlorhexidine digluconate 2% solution as a positive control were used to evaluate the model. The tested products were composed of hydrogels made from completely biodegradable starch microspheres carrying different active compounds. The compounds were applied topically and left for 2–4 days. Profiles of oxygen concentration and pH were measured to assess the effect of treatments on bacterial activity. Confocal microscope images were obtained of the models to visualise the existence of microcolonies. Results showed that the modified in vitro model maintained a stable number of the two bacterial species over 6 days. In untreated models, steep oxygen gradients developed and pH increased to &gt;8.0. Hydrogels containing active compounds alleviated the high oxygen consumption and decreased pH drastically. Moreover, all three hydrogels reduced the colony forming units significantly and to a larger extent than the chlorhexidine control treatment. Overall, the modified model expressed several characteristics similar to in vivo chronic wounds.</p

A novel chronic wound biofilm model sustaining coexistence of Pseudomonas aeruginosa and Staphylococcus aureus suitable for testing of antibiofilm effect of antimicrobial solutions and wound dressings

Chronic wounds are a large burden to patients and healthcare systems. Biofilm infections in chronic wounds are crucial factors leading to non‐healing of wounds. It is important to study biofilm in wounds and to develop effective interventions against wound biofilm. This study presents a novel in vitro biofilm model mimicking infected chronic wounds. The novel layered chronic wound biofilm model uses woundlike media and includes both Pseudomonas aeruginosa and Staphylococcus aureus, which have been identified as the most important pathogens in wounds. The model sustains their coexistence for at least 96 h. Microscopy of the model revealed microbial growth in non‐surface attached microcolonies as previously observed in vivo. The model was used to determine log(10)‐reduction for the use of an antimicrobial solution and antimicrobial dressings (containing silver or honey) showing moderate‐to‐low antibiofilm effect, which indicates better concordance with the observed clinical performance of this type of treatment than other widely used standard tests

Watt-class CMOS-compatible optical high power amplifier

High power amplifiers are critical components in optical systems spanning from long range optical sensing and optical communication systems to micromachining and medical surgery. Today, integrated photonics with its promise of large reductions in size, weight and cost cannot be used in these applications, due to the lack of on-chip high power amplifiers. Integrated devices severely lack in output power due to their small size which limits energy storage capacity. For the last two decades, large mode area (LMA) technology has played a disruptive role in fiber amplifiers enabling a dramatic increase of output power and energy by orders of magnitude. Thanks to the capability of LMA fiber to support significantly larger optical modes the energy storage and power handling capability has significantly increased. Therefore, an LMA device on an integrated platform can play a similar role in power and energy scaling of integrated devices. In this work, we demonstrate LMA waveguide-based CMOS compatible watt-class high power amplifiers with an on-chip output power reaching beyond ~ 1 W within a footprint of only ~ 4 mm2. The power achieved is comparable and even surpasses many fiber-based amplifiers. We believe this work has the potential to radically change the integrated photonics application landscape, allowing power levels previously unimaginable from an integrated device replacing much of today’s benchtop systems. Moreover, mass producibility, reduced size, weight and cost will enable yet unforeseen applications for laser technology