3D-Printed PLA Medical Devices: Physicochemical Changes and Biological Response after Sterilisation Treatments

Abstract

Polylactic acid (PLA) has become one of the most commonly used polymers in medical devices given its biocompatible, biodegradable and bioabsorbable properties. In addition, due to PLA’s thermoplastic behaviour, these medical devices are now obtained using 3D printing technologies. Once obtained, the 3D-printed PLA devices undergo different sterilisation procedures, which are essential to prevent infections. This work was an in-depth study of the physicochemical changes caused by novel and conventional sterilisation techniques on 3D-printed PLA and their impact on the biological response in terms of toxicity. The 3D-printed PLA physicochemical (XPS, FTIR, DSC, XRD) and mechanical properties as well as the hydrophilic degree were evaluated after sterilisation using saturated steam (SS), low temperature steam with formaldehyde (LTSF), gamma irradiation (GR), hydrogen peroxide gas plasma (HPGP) and CO2 under critical conditions (SCCO). The biological response was tested in vitro (fibroblasts NCTC-929) and in vivo (embryos and larvae wild-type zebrafish Danio rerio). The results indicated that after GR sterilisation, PLA preserved the O:C ratio and the semi-crystalline structure. Significant changes in the polymer surface were found after HPGP, LTSF and SS sterilisations, with a decrease in the O:C ratio. Moreover, the FTIR, DSC and XRD analysis revealed PLA crystallisation after SS sterilisation, with a 52.9% increase in the crystallinity index. This structural change was also reflected in the mechanical properties and wettability. An increase in crystallinity was also observed after SCCO and LTSF sterilisations, although to a lesser extent. Despite these changes, the biological evaluation revealed that none of the techniques were shown to promote the release of toxic compounds or PLA modifications with toxicity effects. GR sterilisation was concluded as the least reactive technique with good perspectives in the biological response, not only at the level of toxicity but at all levels, since the 3D-printed PLA remained almost unaltered.

3D printing of PLA:CaP:GO scaffolds for bone tissue applications

“…The two characteristic diffraction peaks in the spectrum of 3D printed PLA alone (named as PLA:0CaP:0GO) were found at positions 16.5° and 21.5°, corresponding to (200)/(110) and (015) crystal planes, respectively. 54 When low contributions of CaP and GO are present in the scaffold, differences at the diffraction patterns were observed, as a less intense diffraction peak for the (200)/(110) crystal plane, which suggest lower crystallinity degree. The presence of CaP is clearly detected in the diffraction pattern of the scaffold with the highest contribution, 13.2 at%, with the main peaks at positions 31.8°, 32.2°, 32.9°and 39.9°, which correspond to planes (121), (112), (300) and (310).…”

A Study of PLA Thin Film on SS 316L Coronary Stents Using a Dip Coating Technique

“…The exhibited bands at 3300 cm −1 and 1636 cm −1 in the PLA pellet spectra correspond to O–H group vibrations and hydrated H 3 O + [ 62 , 63 , 64 ]. The band detected at 1748 cm −1 was attributed to the stretching mode of carbonyl vibration C=O [ 65 , 66 , 67 ]. At 1452 and 1361 cm −1 , there were bending frequencies for C–H asymmetric and symmetric stretching in the –CH 3 methyl groups, respectively [ 67 , 68 ].…”

Thermal Behavior of Graphene Oxide Deposited on 3D-Printed Polylactic Acid for Photothermal Therapy: An Experimental–Numerical Analysis

“…Some of the most investigated polymers are collagen, alginate, chitosan, polyvinyl alcohol, poly(ϵ-caprolactone), and polylactic acid (PLA), among others [ 21 ]. In the particular case of PLA, interest in this biocompatible, biodegradable, and bioabsorbable polymer has risen dramatically with the emergence in the biomedical field of fused deposition modeling (FDM), one of the most common 3D printing techniques [ 22 ]. In this regard, PLA presents thermoplastic properties and a low glass transition temperature (55–65 °C), which means that it is deformable under high temperatures (190–220 °C).…”

“…In this regard, PLA presents thermoplastic properties and a low glass transition temperature (55–65 °C), which means that it is deformable under high temperatures (190–220 °C). Moreover, it can be heated to its melting point, cooled, and then reheated again without significant degradation [ 22 , 23 ]. Its use in FDM technology enables the rapid manufacture of customized devices for biomedical applications.…”