Ti₃C₂T_<i>x</i> MXene augments osmo-adaptive repression of the inflammatory stress response for improved wound repair

Chronic non-healing wounds represent a growing global health challenge that is poorly addressed by current advances in wound care dressings. Hyperosmotic stress linked, for example, to poor glycaemic control, is a known but under-investigated contributor to the chronic wound environment and a known inflammatory stimulus. MXene (Ti₃C₂T_<i>x</i>) has been considered for smart dressing applications but has not been investigated for use with bioactive agents to directly moderate hyperosmotic stress for improved wound care. In this study, Ti₃C₂T_<i>x</i>, in combination with osmolyte betaine, was used to investigate hyperosmotic stress-induced effects on wound closure. The effect of these materials was measured using a wound closure scratch assay, and data was used to mathematically model changes in HaCaT human keratocyte migratory rate and velocity. Changes in the upregulation of apoptotic and inflammatory markers were measured, and qualitative changes in phalloidin-labelled actin cytoskeletal structure were observed. A <i>tert</i>-butyl glycine betainate (<i>t</i>Bu-GB) polyacrylate microgel loaded Ti₃C₂T_<i>x</i> dressing was then fabricated and tested for biocompatibility and slow elution of osmolyte over time. Osmotic stress at levels that did not induce cell death reduced the migratory capacity of keratocytes to close the scratch. Migration by osmotically stressed keratocytes was reduced by more than 50% at 24 h and remained at 65% (±5%) at 48 h compared to complete scratch closure at 24 h in the cell only control. This reduction was reversed by a Ti₃C₂T_<i>x</i> coating, allowing complete scratch closure by 48 h in the osmotically stressed group. Exposure of osmotically stressed cells to betaine increased normalised wound closure in the osmotically stressed keraotycte group at each time point and this was augmented by the presence of a Ti₃C₂T_<i>x</i> coating. Osmotic stress induced upregulation of inflammatory markers IL-6, IL-1α, IL-1β, CXCL1, and CXCL8 by at least 10-fold. The effect was significantly greater in the presence of bacterial LPS and this was significantly reduced by the presence of Ti₃C₂T_<i>x</i> alone and in combination with betaine. Sustained and slow release of betaine was demonstrated from a <i>t</i>Bu-GB-microgel loaded Ti₃C₂T_<i>x</i> dressing over 48 h supporting the use of such dressings to improve osmotic stress induced, poor wound closure rates.