Development of a photocrosslinkable bioink based on chondroitin sulfate adapted for extrusion 3D printing

• Grant number: 24/15898-7
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: February 20, 2025
• End date: February 19, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Luiz Henrique Catalani
• Grantee: Amanda Araujo Domingues
• Supervisor: Prashant Kumar Sharma
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: University Medical Center Groningen (UMCG), Netherlands
• Associated to the scholarship: 21/00490-4 - Study of functional and photoreticulable hydrogels derived from biopolymers for application in 3D printing, BP.DD

Abstract

This project involves a research internship at the Biomaterials & Biomedical Technology group of the University Medical Center Groningen (BBT-UMCG) through the BEPE/FAPESP PhD Program for 12 months. The objective of this work is to study the 3D extrusion printing of photopolymerizable and biocompatible resins based on chondroitin sulfate.Pre-printing tests are necessary to improve the bioink formulation and establish suitable processing parameters for extrusion. Therefore, rheological studies will be conducted to optimize the bioink formulation, and a crosslinking gradient model will be developed using a 405 nm radiation chamber.The 3D extrusion printer Cell Ink Bio X, D-Bioplotter Manufacturer series from Envision TEC Desktop Health, equipped with three print heads and UV light coupling, and the Low Load Compression Tester (LLCT) technique, are sophisticated tools available at UMCG. The aim is to study the mechanical properties of the crosslinked material, such as stiffness and relaxation, and correlate them with enhanced cell adhesion, proliferation, and differentiation. Additionally, the project seeks to enable the printing of bioink with two different cell types: osteoblasts and chondrocytes.Recently, during the PhD research, our group at LBP has developed methods for the functionalization of chondroitin sulfate. The characterization of methacrylated chondroitin sulfate (CS-MA) confirmed the successful incorporation of methacrylate units into CS, with a degree of substitution of 80%. Furthermore, the functionalization of CS with L-histidine (His) via carbodiimide-mediated amide coupling reaction showed a functionalization degree of 21%. CS-His is used as a model for future bioconjugation of the signaling peptide GRGDS onto CS.The resins were produced with CS-MA, CS-His, and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as a photoinitiator in PBS as a solvent. Curing was achieved using a UV chamber (405 nm) for 1 and 5 minutes. Thus, CS-MA resin has the potential to be applied in two types of 3D printing: DLP as a scaffold (ongoing in Brazil) and extrusion as bioink (the focus of this BEPE project).In a previous visit to UMCG, the student had a first contact with the LLCT technique and developed rheological methods to evaluate chondroitin sulfate resin formulations (pre-printing), as well as initiated a promising collaboration with Associate Professor Prashant K. Sharma, an expert in correlating mechanical and viscoelastic properties with cell viability using LLCT.In this context, a long-term visit to BBT-UMCG will provide access to cell advanced culture facilities, a rheometer, and advanced extrusion printers, thereby complementing and enhancing the scientific impact of this work.