Investigation of bioprintable modified agar-based hydrogels with antimicrobial properties

Due to the numerous dangers arising from excessive use of antibiotics in treatments, researchers have been searching for natural alternatives to conventional antibiotics. Despite the popularity of plant extracts, essential oils, and their derivatives in herbal medicine, their applications in novel therapies are rather limited. This paper tries to open a new possibility for infection treatments by assessing the suitability of antimicrobial hydrogels as bioinks. Antimicrobial activity against S. epidermidis, P. aeruginosa, S. aureus, E. coli of selected extracts and geraniol were investigated. Suitable agent was incorporated into agar-based hydrogel. Physicochemical properties of the obtained compositions were analyzed, including determination of swelling kinetics and key polymer network parameters, contact angle measurements, FTIR spectra analysis, biocompatibility assessment, antimicrobial tests and bioprintability studies. Results confirmed geraniol's superior antimicrobial activity in pure form and in hydrogels. The obtained materials showed high swelling capacity, satisfying extrusion processability, shape fidelity, and great biocompatibility in their unmodified state. Nevertheless, modification with geraniol caused a significant decrease of cell viability, which limits their usage as bioinks in current form, due to the cytotoxic effect on cells. To improve cells interactions, studies on materials with geraniol and other agents with similar mechanism should be conducted in the future.