Biomimetic Hierarchical Structuring of PLA by Ultra-Short Laser Pulses for Processing of Tissue Engineered Matrices: Study of Cellular and Antibacterial Behavior

Abstract

The influence of ultra-short laser modification on the surface morphology and possible chemical alteration of poly-lactic acid (PLA) matrix in respect to the optimization of cellular and antibacterial behavior were investigated in this study. Scanning electron microscopy (SEM) morphological examination of the processed PLA surface showed the formation of diverse hierarchical surface microstructures, generated by irradiation with a range of laser fluences (F) and scanning velocities (V) values. By controlling the laser parameters, diverse surface roughness can be achieved, thus influencing cellular dynamics. This surface feedback can be applied to finely tune and control diverse biomaterial surface properties like wettability, reflectivity, and biomimetics. The triggering of thermal effects, leading to the ejection of material with subsequent solidification and formation of raised rims and 3D-like hollow structures along the processed zones, demonstrated a direct correlation to the wettability of the PLA. A transition from superhydrophobic (θ > 150°) to super hydrophilic (θ < 20°) surfaces can be achieved by the creation of grooves with V = 0.6 mm/s, F = 1.7 J/cm2. The achieved hierarchical architecture affected morphology and thickness of the processed samples which were linked to the nature of ultra-short laser-material interaction effects, namely the precipitation of temperature distribution during material processing can be strongly minimized with ultrashort pulses leading to non-thermal and spatially localized effects that can facilitate volume ablation without collateral thermal damage The obtained modification zones were analyzed employing Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), Energy dispersive X-ray analysis (EDX), and optical profilometer. The modification of the PLA surface resulted in an increased roughness value for treatment with lower velocities (V = 0.6 mm/s). Thus, the substrate gains a 3D-like architecture and forms a natural matrix by microprocessing with V = 0.6 mm/s, F = 1.7 J/cm2, and V = 3.8 mm/s, F = 0.8 J/cm2. The tests performed with Mesenchymal stem cells (MSCs) demonstrated that the ultra-short laser surface modification altered the cell orientation and promoted cell growth. The topographical design was tested also for the effectiveness of bacterial attachment concerning chosen parameters for the creation of an array with defined geometrical patterns.

Modeling Experimental Parameters for the Fabrication of Multifunctional Surfaces Composed of Electrospun PCL/ZnO-NPs Nanofibers

“…The second one is that the contact angle values for beaded fibers samples (8 wt% PCL) are higher than bead-free fibers samples (12 wt% PCL) [73], the contact angle values being higher for the samples with lower than average fiber diameter. Another important conclusion is that the thinner beaded fibers showed a higher surface roughness and, therefore, the samples showed higher water contact angle values than the thicker bead-free fibers, respectively [74,75]. This effect associated to the design of a multilevel fiber-bead structure has been reported [76] with the aim of obtaining a higher surface roughness, demonstrating that a good control over the operational parameters such a low applied voltage and a high flow rate produces an increase of the resultant surface roughness.…”

Optimizing the Surface Structural and Morphological Properties of Silk Thin Films via Ultra-Short Laser Texturing for Creation of Muscle Cell Matrix Model

“…All analyses of the fs structured samples that followed were averaged on ten separate measurements and performed in respect to the control, a laser non-treated SF scaffold. An illustrative scheme of the experimental setup is given elsewhere [60].…”

“…Ultra-short pulse laser treatment is a non-contact, non-invasive, non-destructive, and fully biocompatible method, which generates controlled porosity in biopolymer-based cell matrices [54]-this type of modification leads to the creation of micro and nano structures on the surface of the material that can strongly affect cell adhesion, orientation, and differentiation [48,55]. The method relies on control over the surface characteristics of biomaterials, and accordingly, the growth of future muscle tissue can be directed in the desired direction as microchannels/microgrooves with precisely controlled dimensions, and periodicity can be generated on the scaffold surface in a highly reproducible manner [56][57][58][59][60]. This is very important for muscle tissue engineering, as aligned surface structures are the key to obtaining natural muscle cells' morphology and orientation [61,62].…”

Improvement in Thermal Stability of Flexible Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) Bioplastic by Blending with Native Cassava Starch

“…Among bioplastics, poly(L-lactic acid) or poly(L-lactide) (PLLA) is a promising substitute for traditional petroleum-based plastics in many fields, such as biomedical, tissue engineering, drug delivery and packaging applications [ 1 , 2 , 3 , 4 ]. This is due to its excellent biodegradability, biocompatibility and compostability, as well as being environmentally friendly and having good processability and feasibility for an increased production scale [ 5 , 6 ].…”