Table 2.
Summary of the state-of-the-art since 1990 regarding the sterilization of polylactic acid (PLA) based materials for biomedical devices.
| Material | Sterilization Method | Characterization Method | Changes after Sterilization | References | |
|---|---|---|---|---|---|
| Physicochemical Evaluation | Biological Evaluation | ||||
| PLA | Steam heat | Molecular weight Mechanical properties |
- | Yes | [22] |
| Lactide copolymers | Dry heat | Molecular weight/Mechanical properties/DSC | - | Yes | [21] |
| PLLA | EtO Gamma radiation |
Molecular weight (GPC)/Mechanical tests/FTIR/DSC/Degradation studies | - | No Yes |
[33] |
| Microspheres of PLA and PLGA | scCO2 | Degradation analysis/DSC/FTIR | Microbiological | No | [53] |
| Poly (96 L/4D-lactide) | Steam heat EtO Gamma irradiation |
Mass loss/Molecular weight/DSC/Degradation studies | Cytotoxicity | Yes Yes Yes |
[23] |
| Spin-cast films Me.PEG-PLA copolymer | UV radiation | Protein adsorption (XPS)/Surface topography (AFM)/Molecular weight (GPC)/Composition (H-NMR)/Water soluble fraction (GPC) | Cell adhesion | No (in 2 h) Yes (after 5 to 24 h) |
[51] |
| PLLA pellets | EtO | Mechanical properties/Molecular weight/DSC/GPC/XRD/Raman | - | Yes (slight changes) | [34] |
| PLA orthopaedic implant | HPGP (Sterrad) EtO |
Molecular weight (GPC)/DSC/Mechanical properties/WAXD/Contact angle/ATR-FTIR/H2O2 residuals | - | Yes Yes |
[36] |
| Fluconazole- PLA or PLLA implantable delivery rods | Gamma radiation | Loading efficiency/PLC/XRD/GPC | In vivo release assays | Yes | [44] |
| Hydroxyapatite/PLLA composite biomaterial | Gamma radiation | SEM/GPC/TGA/Mechanical properties | - | Yes (acceptable) | [10] |
| PLA films | UV radiation | Molecular weight (GPC)/Contact angle | - | Yes | [52] |
| PLA ultrasound contrast agents | O2 Plasma | Acoustic properties/Surface morphology/Zeta potential | - | Yes | [41] |
| Poly-L-lactide electrospun scaffold | Absolute ethanol Dry oven Steam heat UV radiation HPGP |
SEM/ATR-FTIR/DSC | Microbiological sterility assay | Yes (UV and HPGP the most efficient) | [28] |
| PLA based ultrathin fibers for osteoconductive bone scaffolds | Gamma radiation | SEM/ATR-FTIR/DSC/TGA | Cell viability Cell anchorage |
No | [45] |
| 3D scaffolds and 2D film with a graft copolymer of PLA for tissue engineering | Gamma radiation | - | Cytotoxicity | Yes | [42] |
| PLA and PLGA guided tissue regeneration | Gamma radiation EtO (only PLAG) |
FTIR/DSC/TGA/SEM | Microbiological | Yes | [46] |
| PLA (70:30) coated with plasma polymerized Allylamine fibre meshes | Gamma radiation | XPS | Cell morphology In vivo studies |
No and changes in cell spreading | [47] |
| PLLA porous scaffolds | scCO2 | DSC/SEM/Crystallinity | Microbiological Biocompatibility |
No | [54] |
| Electrospun PLA fiber alignment for biomedical applications | EtO UV irradiation Gamma irradiation |
FTIR/DSC/Contact angle/SEM/Fibre alignment quantification (FFT) | Cell adhesion Cell proliferation |
Yes No No |
[35] |
| PLA films | Saturated steam Ethylene oxide HPGP E-beam radiation Gamma radiation |
ATR-FTIR/DSC/Contact angle/Crystallinity/Colorimetry | - | Yes (not recommended) The rest of techniques do not produce significant changes |
[26] |
| PLA | Low temperature plasma | - | Mortality of several microorganisms | - | [40] |
| PLA films | EtO | TGA/DSC/FTIR | Citotoxicity (MTT) in vivo Histology |
No | [37] |
| PLA flat sheets (for single-use, disposable medical devices) | Saturated steam EtO E-beam HPGP |
Molecular weight (GPC)/WAXD/DSC/FTIR/Mechanical properties | - | EtO and saturated steam are discarded. Recommends the use of e-beam and HPGP |
[27] |
| PLA thin films for corneal implants | Steam sterilization | SEM/Contact angle/ Surface topography | In vivo assays (implants in corneal rabbits) | Yes | [25] |
| PLA thin films | Steam sterilization | SEM/Surface topography/Contact angle/FTIR | Yes | [24] | |
| Commercial PLA | E-beam | Molecular weight/Yellow index/WAXD/DSC/Mechanical properties | - | Yes (at higher doses) | [48] |
| PLA films | E-beam Gamma radiation |
Color analysis/surface tension/FTIR/DSC/Mechanical properties/Molecular weight/Permeability | - | Yes | [50] |
Abbreviation: EtO: ethylene oxide; HPHP: hydrogen peroxide gas plasma; UV: ultraviolet; scCO2: supercritical carbon dioxide; e-beam: electron-beam.