Rose Bengal-incorporated supramolecular gels as a topical platform for localized antimicrobial photodynamic therapy<br />

Abstract

Efficient and localized singlet oxygen (SO) generation is essential for improving antimicrobial photodynamic therapy (aPDT). In this study, a bis-imidazolium-based amphiphilic gelator is used, which self-assembles into a supramolecular gel in a water–ethanol medium and incorporates Rose Bengal (</span><strong style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">RB</strong><span style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">) as a photosensitizer. The gel network provides a confined environment that promotes SO formation under light irradiation. </span><strong style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">RB</strong><span style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">@Gel was characterized with respect to its morphology, degradation behavior, and swelling properties. Biopharmaceutical assessment included in vitro release, ex vivo permeation studies and Hen’s Egg Test–Chorioallantoic Membrane (HET-CAM) assay. Rheological measurements confirmed a viscoelastic profile, indicating structural stability and suitability for localized therapeutic applications. SO production within the gel was quantified using tetrasodium 9,10-anthracenediyl-bis(methylene)dimalonate (NaABMA), showing higher efficiency than that of </span><strong style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">RB</strong><span style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )"> in solution. The </span><strong style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">RB</strong><span style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">@Gel exhibited significant aPDT against </span><em style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">E. coli</em><span style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )"> in a direct-surface contact assay. Overall, the </span><strong style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">RB</strong><span style="background-color:rgb( 255 , 255 , 255 );color:rgb( 34 , 34 , 34 )">@Gel provides a stable, suitable platform capable of efficient SO generation and potent antibacterial activity, highlighting its promise for localized aPDT applications.