Structural and therapeutic properties of salicylic acid-solubilized Pluronic solutions and hydrogels

Soft Matter. 2024 Feb 28;20(9):2075-2087. doi: 10.1039/d4sm00079j.

Abstract

Salicylic acid (SA) finds extensive applications in the treatment of rheumatic and skin diseases because of its analgesic, anti-inflammatory and exfoliating properties. As it is lipophilic in nature, there is a need for appropriate delivery systems to harness these properties for different applications. Herein, we examined the suitability of Pluronic P123/F127 micellar systems as delivery media by investigating the structural, flow and antimicrobial properties of P123/F127-SA solutions and hydrogels using DLS, SANS, rheological and zone inhibition measurement techniques. SA modulates the aggregation characteristics of these surfactant systems and brings about spherical-to-worm-like micelle-to-vesicular structural transitions in the hydrophobic Pluronic P123 system, a spherical-to-worm-like micellar transition in the mixed P123/F127 system and an onset of inter-micellar attraction in the hydrophilic Pluronic F127 system. SA-solubilized systems of both hydrophobic and hydrophilic Pluronics inhibit the growth of Gram-positive and Gram-negative bacteria with comparable MIC values. This suggests that the interaction of SA molecules with the bacterial cell membrane remains unobstructed upon encapsulation in Pluronic micelles. F127 hydrogel-based SA formulations with rheological properties suitable for topical applications and up to 15% SA loading were prepared. These will be useful SA ointments as F127 is an FDA-approved excipient for topical drug delivery applications. The results indicate that Pluronics remain effective as delivery agents for SA and exhibit interesting structural polymorphism upon its solubilization.

MeSH terms

  • Anti-Bacterial Agents
  • Gram-Negative Bacteria
  • Gram-Positive Bacteria
  • Hydrogels*
  • Micelles
  • Poloxalene*
  • Poloxamer* / chemistry
  • Polyethylenes*
  • Polypropylenes*
  • Salicylic Acid / pharmacology

Substances

  • pluronic block copolymer P123
  • Poloxamer
  • UCON 50-HB-5100
  • Hydrogels
  • Salicylic Acid
  • Anti-Bacterial Agents
  • Micelles
  • Poloxalene
  • Polyethylenes
  • Polypropylenes