Abstract
An optimal medical scaffold should be biocompatible and biodegradable and should have adequate mechanical properties and scaffold architecture porosity, a precise three-dimensional shape, and a reasonable manufacturing method. Polylactic acid (PLA) is a natural biodegradable thermoplastic aliphatic polyester that can be fabricated into nanofiber structures through many techniques, and electrospinning is one of the most widely used methods. Medical fiber mat scaffolds have been associated with inflammation and infection and, in some cases, have resulted in tissue degradation. Therefore, surface modification with antimicrobial agents represents a suitable solution if the mechanical properties of the fiber mats are not affected. In this study, the surfaces of electrospun PLA fiber mats were modified with naturally occurring l-ascorbic acid (ASA) or fumaric acid (FA) via a plasma treatment method. It was found that 30 s of radio-frequency (RF) plasma treatment was effective enough for the wettability enhancement and hydroperoxide formation needed for subsequent grafting reactions with antimicrobial agents upon their decomposition. This modification led to changes in the surface properties of the PLA fiber mats, which were analyzed by various spectroscopic and microscopic techniques. FTIR-ATR confirmed the chemical composition changes after the modification process and the surface morphology/topography changes were proven by SEM and AFM. Moreover, nanomechanical changes of prepared PLA fiber mats were investigated by AFM using amplitude modulation-frequency modulation (AM-FM) technique. A significant enhancement in antimicrobial activity of such modified PLA fiber mats against gram-positive Staphylococcus aureus and gram-negative Escherichia coli are demonstrated herein.
Highlights
Surgical procedures are routinely performed for the repair and/or replacement of damaged tissue caused by disease or trauma
The surface modification of polylactic acid (PLA) electrospun fiber mats with covalently bonded ascorbic acid (ASA) or fumaric acid (FA) through plasma treatment was performed for the first time by our knowledge and this study provides complex approach for the preparation of antimicrobial surfaces applicable in medicinal polymeric oriented applications
Information regarding the 2D surface morphology of the prepared PLA fiber mats obtained by scanning electron microscopy (SEM) is summarized in Fig. S1, Supporting Information
Summary
Surgical procedures are routinely performed for the repair and/or replacement of damaged tissue caused by disease or trauma. Various polymeric materials utilizing 3D porous structures have been applied in scaffold fabrication; these materials include polyurethane, poly-ε-caprolactone, polytetrafluoroethylene, polyethylene glycol hydrogels, and polylactic acid (PLA) [3] These materials have adequate mechanical properties and show low infection susceptibility after their in vivo degradation [4,5,6]. The major problem of using scaffolds in tissue engineering is their susceptibility to infection as a result of bacteria colonization and subsequent proliferation, resulting in biofilm formation [24,25] Various bacterial pathogens such as Staphylococci and Streptococci are responsible for serious infections in wound sites, and these bacteria are often present on the skin [26]. The surface modification of PLA electrospun fiber mats with covalently bonded ASA or FA through plasma treatment was performed for the first time by our knowledge and this study provides complex approach for the preparation of antimicrobial surfaces applicable in medicinal polymeric oriented applications
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