# Preserving Microstructure Enhances Cohesion and Mechanical Performance in Spirulina-Based 3D-Printed Biomaterials

## TL;DR

Preserving the natural structure of Spirulina improves the strength and printability of 3D-printed biomaterials compared to disrupted cell structures.

## Contribution

The study introduces a novel approach to using Spirulina's native microstructure to enhance mechanical performance in 3D-printed bioinks.

## Key findings

- Trichome-based biocomposites showed 499% higher rheological yield stress compared to lysed biocomposites.
- Trichome biocomposites exhibited lower shrinkage and up to 108% higher compressive yield strength after dehydration.
- Preserved cell walls provided mechanical interlocking and better stress transfer in printed materials.

## Abstract

Spirulina
platensis is a promising bioresource
for developing structural materials, offering a renewable alternative
to conventional polymers due to its rapid growth and characteristic
helical microstructure. While its biochemical properties have been
widely studied, the role of cellular morphology in determining macroscale
mechanical performance remains underexplored. In this work, we examine
how maintaining versus disrupting Spirulina’s
native trichome structure and cell walls impacts the cohesion, rheology,
and mechanical behavior of 3D-printed biomaterials. Using hydroxyethyl
cellulose (HEC) as a binder, we developed two classes of bioinks:
trichome biocomposites, based on freeze-dried Spirulina trichomes, and lysed biocomposites, formed from thermally lysed Spirulina cells. Differential scanning calorimetry revealed
stronger molecular interactions between lysed cells and HEC, while
trichomes contributed instead via physical interlocking and structural
integrity of the cell wall. Despite weaker molecular interactions,
trichome-based biocomposite bioinks exhibited higher viscosity, improved
printability, and higher rheological yield stress by up to 499%. Upon
dehydration, trichome biocomposites showed lower shrinkage and higher
mechanical performance under compression, with normalized compressive
modulus and yield strength significantly exceeding that of lysed biocomposites
(by up to 107% and 108%, respectively). These effects are attributed
to mechanical interlocking and enhanced stress transfer through intact
cell walls. Our findings demonstrate that preserving biological microstructure
may enable improved material cohesion and function, offering design
principles for scalable, sustainable biofabrication of algae-based
structural materials.