Cold plasma treatment of porous scaffolds: Design principles

Abstract

Three-dimensional porous scaffolds have the potential to revolutionize a number of fields, including stem cell research, biomedical implants, tissue engineering, and regeneration, as well as energy technologies, filtration, and sensing. The ability to precisely engineer their surface properties is paramount to successful and enduring application. Plasma treatments promise to deliver homogeneous surfaces with tailored characteristics while generating few by-products and not relying on the diffusion of liquids into a porous network. However, forming plasma inside complex interconnected pores is a significant challenge and requires much parameter fine-tuning. This study uses numerical modeling to investigate key parameters which affect plasma breakdown and makes practical recommendations for achieving treatment homogeneity. We consider a dielectric barrier discharge (DBD) system, where nitrogen gas flows through a glass tube containing a porous scaffold, which is surrounded by a cylindrical electrode, with ground electrodes at either end of the tube. The parameters investigated include the scaffolds' pore size and porosity as well as electrode size and position. The results showed that homogeneous treatment is achieved by avoiding alternative breakdown pathways such as a poor seal between the scaffold and the glass containment tube, using a narrow supply electrode centered at the scaffold, and positioning ground electrodes as close as possible to the supply electrode without arcing. This strategy maximizes the electric field strength at a given voltage, allowing for higher pressures to be used, which in turn give a more homogeneous mean free path inside the pores.

A cost-effective and enhanced mesenchymal stem cell expansion platform with internal plasma-activated biofunctional interfaces

“…The flow of nitrogen gas through the scaffolds and the electrostatic field established within the reactor were simulated in 3D using the finite element software COMSOL Multiphysics, and is detailed in Redzikultsava et al [ 47 ]. The nitrogen was modelled as a laminar, fully compressible flow in a steady state under a range of conditions.…”

Surface Bio‐engineered Polymeric Nanoparticles

“…Non-depositing plasma processes, such as plasma immersion ion implantation (PIII) and atmospheric pressure plasma treatment, modify the surfaces via physical and/or chemical changes without depositing an additional layer. [66,[101][102][103][104][105] Depositing plasmas, on the other hand, coat the surfaces of substrates with either an additional layer like plasma polymer films [106][107][108][109][110][111] and magnetronsputtered coatings [112][113][114][115][116][117] or synthesize new material such as nanoparticles. [118][119][120][121] The plasma processes share a common underlying concept: The electrons in the plasma are accelerated by electric fields, and they excite the reactant gases, resulting in ionization, radical fragmentation, and enhanced plasma phase chemistry.…”

“…Non‐depositing plasma processes, such as plasma immersion ion implantation (PIII) and atmospheric pressure plasma treatment, modify the surfaces via physical and/or chemical changes without depositing an additional layer. [ 66,101–105 ] Depositing plasmas, on the other hand, coat the surfaces of substrates with either an additional layer like plasma polymer films [ 106–111 ] and magnetron‐sputtered coatings [ 112–117 ] or synthesize new material such as nanoparticles. [ 118–121 ]…”

Cellular modifications and biomaterial design to improve mesenchymal stem cell transplantation

“…224 Porous scaffolds are also shown to be surface modified across the scaffold thickness using packed-bed plasma ion implantation. 225,226 Surface modification enables scaffolds to be functionalised with cell-instructive biomolecules such as extracellular matrix proteins, peptide motifs, cytokines, or growth factors. Matrix proteins, such as collagen, fibronectin, laminin, elastin, or vitronectin, and peptide derivatives, have been used to enhance the biocompatibility of implantable materials.…”