Photo-triggered release of an antibiotic from an in situ forming hydrogel for antibacterial wound dressings

摘要

Introduction: Hydrogels have been used as advanced wound dressing materials because of their ability to improve healing rates and wound appearance. Bacterial infections are found to be a prevalent and persistent problem during chronic wound healing and therefore antimicrobial dressings that are able to release of antibiotics using an external trigger are highly advantageous as sustained release is suspected of causing bacterial resistance. Using light as a trigger is of a considerable interest due to its non- invasive stimulation. Herein, we present a newly designed antimicrobial hydrogel for 'spray on' wound dressing applications in which the timing and amount of antibiotic release can be controlled by UV light. Methodology: A representative antibiotic ciprofloxacin was chemically modified and covalently attached on a clickable PEG hydrogel network through a nitrobenzyl carbamate photolabile group. Both the hydrogel network formation and antibiotic attachment were based on a bio-orthogonal catalyst free strain promoted alkyne-zaide cycloaddition (SPAAC). Characterizations were carried out on the hydrogel mechanical properties and drug release properties. Results and discussion: With antibiotic loaded, the hydrogel maintained good mechanical properties and gelation time making it suitable as a 'spray on' wound dressing. NMR results indicated the cleavage of carbamate linkage occurred due to UV irradiation. Both HPLC and bacterial tests further confirmed that the native antibiotic could be cleaved from the hydrogel network using a light stimulus and diffuse into the surrounding environment inhibiting bacteria growth efficiently. The amount of drug released was quantitatively measured by HPLC and that the UV light not only triggered the release but also control the amount by different UV dosage as well. Conclusion: Together with the relative fast gelation time, the results suggest using the photo responsive strategy to deliver antibiotics provides control over the timing and dose making it potentially suitable for external wound dressing applications.