Abstract
The application of chitosan (CS) and whey protein (WP) alone or in combination in 3D/4D printing has been well considered in previous studies. Although several excellent reviews on additive manufacturing discussed the properties and biomedical applications of CS and WP, there is a lack of a systemic review about CS and WP bio-inks for 3D/4D printing applications. Easily modified bio-ink with optimal printability is a key for additive manufacturing. CS, WP, and WP–CS complex hydrogel possess great potential in making bio-ink that can be broadly used for future 3D/4D printing, because CS is a functional polysaccharide with good biodegradability, biocompatibility, non-immunogenicity, and non-carcinogenicity, while CS–WP complex hydrogel has better printability and drug-delivery effectivity than WP hydrogel. The review summarizes the current advances of bio-ink preparation employing CS and/or WP to satisfy the requirements of 3D/4D printing and post-treatment of materials. The applications of CS/WP bio-ink mainly focus on 3D food printing with a few applications in cosmetics. The review also highlights the trends of CS/WP bio-inks as potential candidates in 4D printing. Some promising strategies for developing novel bio-inks based on CS and/or WP are introduced, aiming to provide new insights into the value-added development and commercial CS and WP utilization.
Highlights
As reported in previous research, multi-material 3D printing technology (Fab@Home) has been employed to print chocolate, cheese, biscuits, etc. [1]
Fourdimensional printing originated from 3D printing, adding the fourth dimension of “time”, but in contrast to 3D printing, only stimulable smart materials can be used for 4D printing
This review summarizes the preparation of CS and/or whey protein (WP) as bio-ink that fulfill the limitations, requirements of 3D/4D printing, and post-treatment of printed objectives in the food sector
Summary
As reported in previous research, multi-material 3D printing technology (Fab@Home) has been employed to print chocolate, cheese, biscuits, etc. [1]. To accomplish the printing of an object, a layer-by-layer superposition must be applied This means that the printer repeatedly constructs a new thin layer of material based on the previously printed layer, according to the sliced images of a 3D object [2,3]. Compared with 3D printing technology, 4D printing presents the advantage of dynamic adaptability and the ability to print more refined structures. Multiple 3D printing technologies have been applied in many sectors, such as fused deposition modeling (FDM, or fused filament manufacturing), stereolithography (SLA), electro-hydraulic printing (EHDP), selective laser sintering (SLS), etc. These techniques are innovated to adapt different characteristics of printing materials [7].
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