Ultra-Short Laser Surface Properties Optimization of Biocompatibility Characteristics of 3D Poly-ε-Caprolactone and Hydroxyapatite Composite Scaffolds.

Albena Daskalova,Lamborghini Sotelo,Emil Filipov,Silke Christiansen,Gerd Leuchs,Dragomir Tatchev,Ivan Buchvarov,George Sarau,Ekaterina Iordanova,Radostin Stefanov,Georgi Avdeev,Liliya Angelova

doi:10.3390/ma14247513

Abstract

The use of laser processing for the creation of diverse morphological patterns onto the surface of polymer scaffolds represents a method for overcoming bacterial biofilm formation and inducing enhanced cellular dynamics. We have investigated the influence of ultra-short laser parameters on 3D-printed poly-ε-caprolactone (PCL) and poly-ε-caprolactone/hydroxyapatite (PCL/HA) scaffolds with the aim of creating submicron geometrical features to improve the matrix biocompatibility properties. Specifically, the present research was focused on monitoring the effect of the laser fluence (F) and the number of applied pulses (N) on the morphological, chemical and mechanical properties of the scaffolds. SEM analysis revealed that the femtosecond laser treatment of the scaffolds led to the formation of two distinct surface geometrical patterns, microchannels and single microprotrusions, without triggering collateral damage to the surrounding zones. We found that the microchannel structures favor the hydrophilicity properties. As demonstrated by the computer tomography results, surface roughness of the modified zones increases compared to the non-modified surface, without influencing the mechanical stability of the 3D matrices. The X-ray diffraction analysis confirmed that the laser structuring of the matrices did not lead to a change in the semi-crystalline phase of the PCL. The combinations of two types of geometrical designs—wood pile and snowflake—with laser-induced morphologies in the form of channels and columns are considered for optimizing the conditions for establishing an ideal scaffold, namely, precise dimensional form, mechanical stability, improved cytocompatibility and antibacterial behavior.

Highlights

Different types of scaffolds are required for insertion in the place of body injuries in order to facilitate tissue repair
We investigated the influence of femtosecond laser processing on the formation of stripe-like patterns on the surfaces of 3D-printed PCL and PCL/HA scaffolds
The acquired surface designs on the individual struts of PCL and PCL/HA matrices in the form of stripes and micro columns represent a model for the creation of cell-friendly and bacteria-repellent scaffolds

Summary

Introduction

Different types of scaffolds are required for insertion in the place of body injuries in order to facilitate tissue repair. Despite the huge impact that medical implants have on patients’ health and quality of life, the possibility of side effects after implantation remains. One of the most common complications is the development of a bacterial infection associated with the implant itself. S. aureus and S. epidermidis have been listed as the main pathogens that colonize implants and lead to severe inflammation [1]. When the implant is inserted at the site of injury, both human and bacterial cells compete for a place to attach to the material’s surface. The initial adsorption of bacter ia onto an inert and abiotic implant is unspecific and directed mainly by electrostatic, hydrophobic and van der

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