Supercritical Impregnation of PLA Filaments with Mango Leaf Extract to Manufacture Functionalized Biomedical Devices by 3D Printing

Abstract

Polylactic Acid (PLA) filaments impregnated with ethanolic mango leaves extract (MLE) with pharmacological properties were obtained by supercritical impregnation. The effects of pressure, temperature and amount of extract on the response variables, i.e., swelling, extract loading and bioactivity of the PLA filaments, were determined. The analysis of the filaments biocapacities revealed that impregnated PLA filaments showed 11.07% antidenaturant capacity and 88.13% antioxidant activity, which after a 9-day incubation shifted to 30.10% and 9.90%, respectively. Subsequently, the same tests were conducted on printed samples. Before their incubation, the printed samples showed 79.09% antioxidant activity and no antidenaturant capacity was detected. However, after their incubation, the antioxidant activity went down to only 2.50%, while the antidenaturant capacity raised up to 23.50%. The persistence of the bioactive properties after printing opens the possibility of using the functionalized PLA filaments as the feed for a three-dimensional (3D) printer.

Screening of the Supercritical Impregnation of Olea europaea Leaves Extract into Filaments of Thermoplastic Polyurethane (TPU) and Polylactic Acid (PLA) Intended for Biomedical Applications

“…Besides, the mobility of the polymer chains at 55 °C is higher than at 35 °C specifically for thermoplastic polymers such as TPU and for polymers with a glass transition temperature near to the operating temperature, such as PLA. Similar effects were found by Rosales et al in the supercritical impregnation of mango leaf extract into PLA filaments, where higher loadings were obtained at 55 °C than at 35 °C [ 23 ]. Also, Verano-Naranjo and coworkers observed higher loadings of ketoprofen inside PLA at 75 °C than at 35 °C as result of the combination between the higher swelling of the polymer at that temperature and the decrease in the scCO 2 density [ 21 ].…”

“…The authors suggested that two factors contributed to this swelling increase. On the one hand, the presence of ethanol may modify the internal structure of polymer chains favoring their mobility; and on the other hand, at higher pressure, the diffusion of CO 2 inside the polymer could be facilitated [ 23 ]. In comparison with the present work, the higher PLA swelling observed by those authors may be due to the longer contact time employed (24 h vs. 30 min in the present work).…”

“…Regarding the swelling degree, similar values were found by other authors in the supercritical impregnation of PLA filaments with mango leaves extract (10–40%). Although a statistical analysis was not performed, the authors observed higher swelling degrees at higher temperature and pressure [ 23 ]. The single report found for the supercritical impregnation of TPU films showed loading values similar to those obtained in the present work, from 1% for rhodamine B (hydrophobic model drug) to approximately 4% for 7-hydroxycoumarin (hydrophilic model drug) at 150 bar and 40 °C after 4 h [ 33 ].…”

“…The antioxidant activity of the impregnated filaments was spectrophotometrically determined using the DPPH free radical scavenging assay, following a procedure reported in a previous contribution [ 23 ]. First, the antioxidant activity of the ethanolic OLE at different concentrations was determined.…”

“…In a later work, they studied the mechanism of ketoprofen in in vitro release from the impregnated samples [ 22 ]. Rosales et al studied the supercritical impregnation of PLA filaments with ethanolic mango leaves extract using different pressure, temperature, and extract concentration conditions [ 23 ]. Moreover, these authors evaluated the bioactivity of the polymer filament after the printing process, and the antioxidant activity was maintained to a great extent.…”