Effect of storage temperature on the printability of the gelatin - alginate bioink

Abstract

Bioink is a fundamental component of three-dimensional (3D) printing technology, exerting a direct influence on the overall quality, precision, and structural integrity of printed biological constructs. Among various factors influencing printing outcomes, printability is a key determinant for success, as it impacts the precision of printed structures, the consistency of filament formation, and the ability to maintain the correct shape throughout the printing process. The printability of bioink is influenced not only by its composition but also by external conditions, particularly the storage temperature. Therefore, evaluating the impact of storage temperature on bioink printability is essential. This paper presents the evaluation of the effects of three different storage temperature conditions on the printability of gelatin-alginate B-GA bioink over a period of 21 days. These conditions included freezing at -20 ± 1°C, refrigeration at 4 ± 1°C and storage at room temperature of 25 ± 2°C. The printability was assessed by examining various parameters, including the state of the bioink, the ability to form continuous filaments, the uniformity factor (U), the diffusion rate (Df) and the effectiveness of pore formation (Pr). The results showed that the printability of B-GA bioink remained stable during the first 14 days under all three tested storage conditions. However, after 21 days, a significant decline in printability was observed in the cases of freezing and room temperature conditions, proven by the decrease in Pr values of 0.8469 ± 0.0056 and 0.8630 ± 0.0074, respectively. In contrast, refrigeration at 4 ± 1°C allowed the B-GA bioink to retain its printability consistently throughout the entire 21-day period, with a Pr value of 0.908 ± 0.0227. Therefore, in the test, storing B-GA bioink at 4 ± 1°C was the most effective condition for preserving its printability over 21 days.