Surface modification of polylactic acid (PLA) and polyglycolic acid (PGA) monofilaments via the cold plasma method for acupoint catgut-embedding therapy applications

Polylactic acid (PLA) and polyglycolic acid (PGA) monofilaments have been the most recently, widely used acupoint catgut-embedding therapy (ACET) biodegradable materials. However, their poor hydrophilicity and cell adhesion are common limitations during applications. To improve their surface properties, modification technologies should be generally applied. This paper firstly adapted polymer chips to produce four types of PLA and PGA monofilaments, and then attempted cold oxygen plasma treatment for surface modification. Afterwards, the modified monofilaments were fully characterized with respect to structure, mechanical and in vitro properties. The results showed that both the PLA and PGA monofilaments became coarser after modification, and their hydrophilicity was improved, while their weight and diameter sizes were slightly decreased. The tensile properties and flexibility of the modified samples changed little, and their swelling ratio increased sharply. All the prepared samples exhibited good cell viability, with more than 75% of cells being viable. Sample PM-PLA2 (plasma-modified PLA2) and sample PM-PGA2 (plasma-modified PGA2) presented the largest cell attachment ratio (cultured for 48 h) at 52.16% ± 1.05% and 58.39% ± 2.07%, respectively. In sum, this cold plasma method successfully improved the hydrophilicity and in vitro properties of PLA and PGA monofilaments, while retaining the other excellent properties, and warrants further study to develop new PLA and PGA-embedding materials with outstanding clinical efficacy.