Final Report Summary - PLASMATS (Plasma-assisted development and functionalization of electrospun mats for tissue engineering purposes)
The project PLASMATS is investigating the applicability of non-thermal plasmas in the field of electrospinning in an effort to create advanced, functional biodegradable electrospun mats which can be used as tissue engineering scaffolds.
Within the project, we first succeeded in the fabrication of electrospun nanofibers from several natural as well as biodegradable polymers including PCL, PLA, chitosan/PEO and gelatin. By selecting the right solvent mixture as well as the appropriate electrospinning parameters, electrospun mats from the above-mentioned polymers have been created consisting of nicely elongated nanofibers without the presence of beads. Nanofibrous meshes consisting of randomly oriented nanofibers and uniaxial aligned nanofibers have been developed by making use of different electrospinning collectors.
Within the PLASMATS project, an innovative atmospheric pressure plasma jet source has also been developed to enable a plasma treatment of polymer solutions prior to the electrospinning process. This plasma jet has been designed in such a way that an intense contact occurs between the active plasma species and the surrounding polymer solution. Several experiments on PLA and PCL polymer solutions have revealed that the plasma jet can significantly affect the polymer properties as solution conductivity and viscosity strongly increased after plasma modification, while the pH strongly decreased. These observed changes could be attributed to the generation of novel chemical species in the polymer solutions due to the plasma exposure. In addition, it was also found that due to the plasma pre-electrospinning treatment, beads in the PLA and PCL nanofibrous mats could be eliminated, mainly due to the enhanced solution conductivity. Finally, it was also revealed that the performed plasma treatments did not negatively affect the polymer molecular weight nor the mechanical properties of the nanofibers.
The developed electrospun materials have also been subjected to a plasma-assisted surface modification step after the electrospinning process making use of a dielectric barrier discharge in an effort to enhance the cellular interactions on the nanofibers. Several discharge gases such as argon, air, nitrogen and nitrogen/NH3 have been used and the effects of each of these plasma treatments on the physical and chemical characteristics of the nanofibrous mats have been examined. These experiments have enabled us to conclude that plasma treatments can significantly increase the hydrophilicity of the nanofibrous materials by the incorporation of functional oxygen and/or nitrogen groups. In addition, cell studies have also revealed that these plasma modifications are able to significantly increase the cell adhesion and proliferation on these nanofibers. Additionally, protein studies have also revealed that the performed plasma treatments can strongly affect the protein corona patterns on the nanofibers as well as the proteins involved in cell proliferation.
In an final work package, a lot of effort has been put into the deposition of an amino-rich coating on nanofibrous scaffolds making use of plasma polymerization. In a first step, the plasma polymerization of cyclopropylamine was optimized on flat substrates to determine the plasma operational parameters resulting in the deposition of stable coatings containing the highest possible amount of amino groups. After this optimization step, the deposition process was transferred on nanofibrous scaffolds, which were successfully covered with an amino-rich coating. This coating was also found to positively affect cell adhesion on proliferation on the nanofibrous samples.
In general, the PLASMATS project has proven that plasma technology can play a major role in the development of highly functional biodegradable electrospun mats possessing excellent bulk and surface properties for tissue engineering applications.
Within the project, we first succeeded in the fabrication of electrospun nanofibers from several natural as well as biodegradable polymers including PCL, PLA, chitosan/PEO and gelatin. By selecting the right solvent mixture as well as the appropriate electrospinning parameters, electrospun mats from the above-mentioned polymers have been created consisting of nicely elongated nanofibers without the presence of beads. Nanofibrous meshes consisting of randomly oriented nanofibers and uniaxial aligned nanofibers have been developed by making use of different electrospinning collectors.
Within the PLASMATS project, an innovative atmospheric pressure plasma jet source has also been developed to enable a plasma treatment of polymer solutions prior to the electrospinning process. This plasma jet has been designed in such a way that an intense contact occurs between the active plasma species and the surrounding polymer solution. Several experiments on PLA and PCL polymer solutions have revealed that the plasma jet can significantly affect the polymer properties as solution conductivity and viscosity strongly increased after plasma modification, while the pH strongly decreased. These observed changes could be attributed to the generation of novel chemical species in the polymer solutions due to the plasma exposure. In addition, it was also found that due to the plasma pre-electrospinning treatment, beads in the PLA and PCL nanofibrous mats could be eliminated, mainly due to the enhanced solution conductivity. Finally, it was also revealed that the performed plasma treatments did not negatively affect the polymer molecular weight nor the mechanical properties of the nanofibers.
The developed electrospun materials have also been subjected to a plasma-assisted surface modification step after the electrospinning process making use of a dielectric barrier discharge in an effort to enhance the cellular interactions on the nanofibers. Several discharge gases such as argon, air, nitrogen and nitrogen/NH3 have been used and the effects of each of these plasma treatments on the physical and chemical characteristics of the nanofibrous mats have been examined. These experiments have enabled us to conclude that plasma treatments can significantly increase the hydrophilicity of the nanofibrous materials by the incorporation of functional oxygen and/or nitrogen groups. In addition, cell studies have also revealed that these plasma modifications are able to significantly increase the cell adhesion and proliferation on these nanofibers. Additionally, protein studies have also revealed that the performed plasma treatments can strongly affect the protein corona patterns on the nanofibers as well as the proteins involved in cell proliferation.
In an final work package, a lot of effort has been put into the deposition of an amino-rich coating on nanofibrous scaffolds making use of plasma polymerization. In a first step, the plasma polymerization of cyclopropylamine was optimized on flat substrates to determine the plasma operational parameters resulting in the deposition of stable coatings containing the highest possible amount of amino groups. After this optimization step, the deposition process was transferred on nanofibrous scaffolds, which were successfully covered with an amino-rich coating. This coating was also found to positively affect cell adhesion on proliferation on the nanofibrous samples.
In general, the PLASMATS project has proven that plasma technology can play a major role in the development of highly functional biodegradable electrospun mats possessing excellent bulk and surface properties for tissue engineering applications.