Microfabrication of cellulose nanofiber-reinforced hydrogel by multiphoton polymerization

Hiroki Sugiyama,Kaneto Tsunemitsu,Kotaro Obata,Koji Sugioka,Hiroaki Onoe,Mitsuhiro Terakawa

doi:10.1038/s41598-021-90445-7

Hiroki Sugiyama, Kaneto Tsunemitsu + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-90445-7

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Abstract

The mechanical strength of hydrogel microstructures is crucial for obtaining the desired flexibility, robustness, and biocompatibility for various applications such as cell scaffolds and soft microrobots. In this study, we demonstrate the fabrication of microstructures composed of cellulose nanofibers (CNFs) and poly(ethylene glycol) diacrylate (PEGDA) hydrogels by multiphoton polymerization. The stress of the fabricated microstructure during tensile testing increased with an increase in the CNF concentration, indicating that the mechanical strength of the microstructure was enhanced by using CNFs as fillers. Moreover, the swelling ratio of the microstructure increased with increasing CNF concentration in the PEGDA hydrogel. Our results show the potential of the technique for the microfabrication of advanced cell scaffolds and soft microrobots with the desired mechanical strength.

Highlights

The mechanical strength of hydrogel microstructures is crucial for obtaining the desired flexibility, robustness, and biocompatibility for various applications such as cell scaffolds and soft microrobots
The cellulose nanofibers (CNFs) slurry shows comparably lower absorption at 522 nm, which is the laser wavelength used in this experiment, and a higher absorption at approximately 260 nm, which corresponds to the two-photon absorption wavelength
We demonstrated the fabrication of CNF/poly(ethylene glycol) diacrylate (PEGDA) composite microstructures by multiphoton polymerization (MPP)

Summary

Introduction

The mechanical strength of hydrogel microstructures is crucial for obtaining the desired flexibility, robustness, and biocompatibility for various applications such as cell scaffolds and soft microrobots. Because multiphoton polymerization (MPP) is a promising technique that is capable of fulfilling the requirements to fabricate submicron and nanoscale three-dimensional hydrogel structures with precise control of the geometry[9,10], MPP has been applied in tissue engineering[11,12], actuators and soft robotics[13,14], as well as targeted drug delivery[15] For such applications, the mechanical strength of the hydrogel is crucial. In the fabrication of microstructures by MPP using ultrashort pulsed lasers, it was reported that the crosslinking density and Young’s modulus could be changed by varying the laser power and scanning speed[18,19] In the latter case, it is possible to change the mechanical properties of polymer materials by compositing them with fillers. Fabricating CNF-filled composite structures by MPP would provide highly precise structures with desired spatial selectivity, enabling the realization of a wider range of applications for hydrogel-based microstructures

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