Cold atmospheric plasma-treated bioink: A biocompatible RONS delivery platform in 3D bioprinting

In this work, we have developed and characterized a first plasma-treated, cell-laden bioink, composed of Pluronic® F127, alginate, and hyaluronic acid (HA). We assessed the physical and biological properties of the ink, both with and without plasma treatment. The results showed that, with plasma treatment, we were able to generate reactive oxygen and nitrogen species (RONS) in HA solutions with a dependence on HA concentration and achieve near 100% of their release from the complete hydrogel. The material exhibited shear thinning and recovery properties that were not affected by plasma treatment, making it an adequate candidate for 3D printing. Thus, we were able to 3D bioprint stable, manipulatable structures with the plasma-treated ink after optimizing printing parameters. We investigated the influence of plasma treatment of the ink on cell response by varying treatment durations prior to cell inclusion. While the metabolic activity of encapsulated fibroblasts and chondrocytes was preserved in inks treated for up to 1 min, exposure times beyond this threshold induced a time-dependent decrease in metabolic activity. Within printed scaffolds, cells maintain viability but exhibit morphological differences with 60 s of plasma treatment. The outcome of this study is an initial step towards the novel use of plasma-treated hydrogels (PTHs) as bioinks that can deliver plasma-generated RONS to cells without significant toxicity. This expands the emerging field of PTHs from anticancer applications to other uses and establishes the potential of plasma-treated bioinks as platforms for RONS delivery in the field of tissue engineering.