Laser-modified PLGA for implants: in vitro degradation and mechanical properties

Irradiations by CO2 laser poly(lactic-co-glycolic acid) surface lead to alterations of physicochemical properties of a copolymer. Effects of PLGA irradiations are results of photochemical and photothermal processes leading to polymer degradation. The scale of the degradation depends on the inducted surface modification. Hence the main goal of presented studies was to define the influence of CO2 laser irradiation with different process parameters, inducing three cases of surface modification, on mechanical properties and topography of PLGA during degradation in the aqueous environment.

Hydrolytic degradation were performed in distilled (demineralized) water. Mechanical properties were conducted in accordance with the PN-EN ISO 527-3:1998 standard. pH of incubating solution, specimens' topography, mass and geometrical dimensions were controlled during process.

During the hydrolytic degradation, gradual changes in failure mode were observed from ductile failure characteristic for untreated PLGA to brittle failure of incubated PLGA regardless of the case of triggered modification. Tensile strength decreased with degradation time regardless of the case of surface modification with insignificant fluctuation in means Young's moduli. pH for each case decreased and topography od specimens become smoother with incubation time.

PLGA surface modification by CO2 laser below the ablation threshold (P1) and at the ablation threshold (P2) leaded to surface functionalization, however, irradiation above the ablation threshold (P3) caused marked degradation of PLGA and accelerated specimens disintegration during incubation in the aquatic environment.