Atmospheric Pressure Plasma Jet Treatment of Polymers Enables Reagent-Free Covalent Attachment of Biomolecules for Bioprinting

Abstract

Three-dimensional (3D) bioprinting, where cells, hydrogels, and structural polymers can be printed layer by layer into complex designs, holds great promise for advances in medicine and the biomedical sciences. In principle, this technique enables the creation of highly patient-specific disease models and biomedical implants. However, an ability to tailor surface biocompatibility and interfacial bonding between printed components, such as polymers and hydrogels, is currently lacking. Here we demonstrate that an atmospheric pressure plasma jet (APPJ) can locally activate polymeric surfaces for the reagent-free covalent attachment of proteins and hydrogel in a single-step process at desired locations. Polyethylene and poly-ε-caprolactone were used as example polymers. Covalent attachment of the proteins and hydrogel was demonstrated by resistance to removal by rigorous sodium dodecyl sulfate washing. The immobilized protein and hydrogel layers were analyzed using Fourier transform infrared and X-ray photoelectron spectroscopy. Importantly, the APPJ surface activation also rendered the polymer surfaces mildly hydrophilic as required for optimum biocompatibility. Water contact angles were observed to be stable within a range where the conformation of biomolecules is preserved. Single and double electrode designs of APPJs were compared in their characteristics relevant to localized surface functionalization, plume length, and shape. As a proof of efficacy in a biological context, APPJ-treated polyethylene functionalized with fibronectin was used to demonstrate improvements in cell adhesion and proliferation. These results have important implications for the development of a new generation of 3D bioprinters capable of spatially patterned and tailored surface functionalization performed during the 3D printing process in situ.

Plasma Damage Control: From Biomolecules to Cells and Skin

“…The high temperature during plasma treatment, high RONS flux, and energetic UV emissions can lead to cell and tissue damage and must be controlled . Moreover, recent advances in biomedical sciences employ APPJs to locally functionalize and activate scaffolds for enhanced cell adhesion and controlled tissue growth or 3D bio-print biomolecules and cells . Following the development of APPJ-based biomedical technologies, safe and controlled plasma treatment is required when operating with biomaterials.…”

“…32 Moreover, recent advances in biomedical sciences employ APPJs to locally functionalize and activate scaffolds for enhanced cell adhesion and controlled tissue growth 33 or 3D bio-print biomolecules and cells. 34 Following the development of APPJ-based biomedical technologies, safe and controlled plasma treatment is required when operating with biomaterials. Therefore, this study details a systematic investigation of the biological role of UV radiation from plasma, its contribution to the plasma−target interface, and interface control.…”

Covalent Protein Immobilization on 3D‐Printed Microfiber Meshes for Guided Cartilage Regeneration

“…Atmospheric Pressure Plasma Jet (APPJ) Functionalization of MEW Meshes: APPJ treatment settings were used as described previously, [24] with the following modifications: The APPJ was mounted in a 3D printer (FlSun i3 Prusa) modified in-house (Figure S1, Supporting Information). Marlin firmware was edited and uploaded with Arduino.…”

“…When gas flowing through capillaries is ionized by electric fields these devices are referred to as APP jets (APPJs). [21][22][23] Results have shown that dielectric barrier discharge APP systems [20] and APPJs [24] can be used to activate 2D polymeric surfaces to facilitate on-contact covalent immobilization of extracellular matrix proteins in a single-step, reagent-free process. Furthermore, the potential of APPJs to functionalize 3D polymeric meshes and subsequently covalently immobilize biomolecules without the need for wet chemistry processes has yet to be demonstrated.…”

Visualization of Activated Area on Polymers for Evaluation of Atmospheric Pressure Plasma Jets

“…Several gases are used for APPJ treatment of PE, for example, Argon [ 23 , 24 ] or compressed dried air (CDA) [ 19 ]. APPJ improves adhesion to PE in 3D bio-printed structures [ 25 ] or modifies the surface properties of shoulder implants made of ultra-high molecular weight polyethylene (UHMWPE) [ 26 ]. Compared with traditional polymer surfaces activation methods, such as flaming [ 27 , 28 ] or corona treatment [ 29 , 30 , 31 , 32 , 33 ], the APPJs allow the achievement of locally much higher values of surface free energy.…”