Speaker
Description
Introduction
Additive technologies have propelled the popularity of personalized medicine, expanding the adaptation of various biomaterials for additive processing. Sodium alginate (SA) and chitosan (CS) are natural-based, biopolymers that are characterized by simplicity of preparation, ease of modification, and wide availability, and exhibit great potential in additive manufacturing technologies [1–2]. The success of bioplotting dense gel systems relies heavily on understanding and tailoring their rheological and mechanical properties. In this study, we investigate how the incorporation of chitosan into alginate-based gels influences their viscoelastic behaviour, mechanical strength, and overall printability using an extrusion-based bioplotter.
Methods
In this study, a rotational-oscillation rheometer with a parallel plate system was used to analyze the rheological properties of gels. Measurements of viscosity as a function of shear rate were conducted to describe the behavior of non-Newtonian flow in terms of determining the zero viscosity of the solution, the change in viscosity as a function of shear rate, and recovery properties. Oscillation tests were performed to determine the linear range of viscoelasticity, the flow stress, and the relationship between oscillation frequency and viscoelastic properties carried out in variable frequency mode from 0 to 100 Hz at a constant strain rate contained within the LVR range.
Printability was evaluated by printing scaffolds with different fill rates and numbers of layers using a BioX bioplotter (Cellink), analyzing the effect of speed and pressure on print quality. Accuracy was assessed by the width of the printed filament and the size of the pores in the scaffolds measured using a digital microscope. The influence of printing parameters was analyzed using the ANOVA test and η² coefficient in Statistica software (TIBCO Software Inc.).
Results
The addition of chitosan changes the nature of the gels from Newtonian to shear-thinning, which was analyzed based on the parameters of the Power-Law rheological model. The results showed a significant effect of chitosan on the rheological properties of gels, which also translated into their processability with a bioplotter.
By adjusting the concentration ratio of sodium alginate and chitosan accordingly, a significant increase in the values of storage modulus, loss modulus, and complex shear modulus G* was obtained, which directly improved printing accuracy. In particular, the higher value of the complex modulus made it possible to print more layers without losing structural stability and collapse of layers.
Discussion
By correlating shear-thinning behavior, flow stress, and recovery properties with printing outcomes, we demonstrate that chitosan serves as a key modifier, enabling the fabrication of stable and precise 3D structures. Our findings highlight the potential of chitosan–alginate composites as bioink candidates for biomedical applications such as tissue scaffolding and wound healing, where both material performance and biocompatibility are critical.
References
1.H. Liu et al., A functional chitosan-based hydrogel as a wound dressing and drug delivery system in the treatment of wound healing. RSC Adv, vol. 8, no. 14, pp. 7533–7549, Feb. 2018.
2.Á. Aguilar-De-leyva et al., 3D printed drug delivery systems based on natural products. Pharmaceutics, vol. 12, no. 7, pp. 1–20, Jul. 2020.
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