In situ forming antibacterial dextran blend hydrogel for wound dressing: SAA technology vs. spray drying

•High-mannuronic alginate/amidated pectin blend microparticles can be produced by SAA.•Gentamicin loaded dextran particles are able to move rapidly from dry to soft hydrogel.•Moisture transmission of hydrogel is ideal to avoid wound dehydration or occlusion phenomena.•Drug/polymers ratio is related to prolonged release of gentamicin, up to 10 days.•Formulations have good antimicrobial effect and the ability to degrade preformed biofilms. This study focuses on designing microparticulate carriers based on high-mannuronic alginate and amidated pectin blend loaded with gentamicin sulphate able to move rapidly from dry to soft hydrogel. Supercritical assisted atomization was used to produce microparticles in form of dry powder and characteristics were compared with those obtained by spray-drying. Particles with very high encapsulation efficiency (∼100%) and small diameter (less than 2μm) showed good flowability and high fluid uptake enabling wound site filling and limiting bacterial proliferation. Moisture transmission of the in situ formed hydrogel was about 95g/m2h, ideal to avoid wound dehydration or occlusion phenomena. All formulations presented a burst effect, suitable to prevent infection spreading at the beginning of the therapy, followed by prolonged release (4–10 days) related to drug/polymers ratio. Antimicrobial tests showed stronger effect than pure GS over time (up-to 24 days) and the ability to degrade preformed biofilms, essential to properly treat infected wounds.