Background: Triamcinolone acetonide (TAA) is an effective and the most commonly used corticosteroid hormone for the treatment of hypertrophic scars (HSs). However, the clinically used dosage has poor tissue permeability and injection safety. By contrast, lipid nanoparticles (LNPs) have the advantage of high affinity for the skin.
Materials and methods: This article describes the preparation of TAA-LNPs using poly(lactic-co-glycolic acid) as a carrier material, which have good biocompatibility and biodegradability. Based on a systematic investigation of its physicochemical properties, a rabbit ear HSs model was established to evaluate the percutaneous permeability of TAA-LNPs in scar tissue in vitro as well as to assess its curative effect and skin irritation. 
Results: The results showed that the TAA-LNPs formed uniform and round particles under fluoroscopy and had a complex structure in which a nanoparticle core was surrounded by multiple vesicles. The particles were 232.2±8.2 nm in size, and the complimentary potential was -42.16 mV. The encapsulation efficiency was 85.24%, which is greater than that of other common liposomes and nanoparticles. A test of in vitro scar tissue permeability showed that penetration into scar tissue was twofold and 40-fold higher for TAA-LNPs than for common liposome and commercial suspensions, respectively. The concentration of the absorbed drug effectively inhibited fibroblast proliferation, achieved a therapeutic effect in HSs, and did not stimulate intact or damaged skin. 
Conclusion: The preparation of TAA into LNPs for transdermal administration can enhance transdermal permeation performance and the safety of this drug, which is beneficial for the treatment of HSs.
Keywords: lipid nanoparticles, transdermal permeation, triamcinolone acetonide, hypertrophic scars