Quantitative Characterization of Liquid Photosensitive Bioink Properties for Continuous Digital Light Processing Based Printing

Summary

This study uses temperature and material composition to control the yield stress properties of yield stress fluids. The solid-like state of the ink can protect the printing structure, and the liquid-like state can continuously fill the printing position, realizing the digital light processing 3D printing of extremely soft bioinks.

Abstract

Precise printing fabrication of bioinks is a prerequisite for tissue engineering; the Jacobs working curve is the tool to determine the precise printing parameters of digital light processing (DLP). However, the acquisition of working curves wastes materials and requires high formability of materials, which are not suitable for biomaterials. In addition, the reduction of cell activity due to multiple exposures and the failure of structural formation due to repeated positioning are both unavoidable problems in conventional DLP bioprinting. This work introduces a new method of obtaining the working curve and the improvement process of continuous DLP printing technology based on such a working curve. This method of obtaining the working curve is based on the absorbance and photorheological properties of the biomaterials, which do not depend on the formability of the biomaterials. The continuous DLP printing process, obtained from improving the printing process by analyzing the working curve, increases the printing efficiency more than tenfold and greatly improves the activity and functionality of cells, which is beneficial to the development of tissue engineering.

Introduction

Tissue engineering¹ is important in the field of organ repair. Due to the lack of organ donation, some diseases, such as liver failure and kidney failure, cannot be cured well, and many patients do not receive timely treatment². Organoids with the required function of the organs may solve the problem caused by the lack of organ donation. The construction of organoids depends on the progress and development of bioprinting technology³.

Compared with extrusion-type bioprinting⁴ and inkjet-type bioprinting⁵, the printing speed....

Protocol

1. Theoretical preparation

1. Define three parameters: liquid absorbance (A_l), solid absorbance (A_s), and threshold time (t_T)¹⁷.
2. Rewrite the traditional Jacobs working curve using these three parameters¹⁷ according to Equation 1:
        (Equation 1)
   Here, t_H is th.......

Discussion

The critical steps of this protocol are described in section 2. It is necessary to unify the light intensity used in the photorheology test and the printing light intensity in the actual tests. The absorbance testing equipment is the most important part. The shape of the test chamber should be the same as the photosensitive area of the light intensity meter. Due to the properties of the materials that continuously change during the whole UV light exposure process, the light intensity needs to continue to change

Materials

Name	Company	Catalog Number	Comments
Brilliant Blue	Aladdin (Shanghai, China).	6104-59-2
DLP software	Creation Workshop	N/A
Lithium phenyl-2,4,6-trimethylbenzoylphosphinate		N/A	LAP; synthesized
Light source	OmniCure	https://www.excelitas.com/product-category/omnicure-s-series-lamp-spot-uv-curing-systems	365 nm
Polyethylene (glycol) diacrylate	Sigma-Aldrich	455008	PEGDA Mw ~700
Rheometer	Anton Paar, Austria	MCR302