Thermoresponsive Alginate-Graft-pNIPAM/Methyl Cellulose 3D-Printed Scaffolds Promote Osteogenesis In Vitro.

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Developing advanced hydrogels for bone tissue engineering requires materials with tunable mechanical properties and excellent biocompatibility.
• Sodium alginate and methylcellulose are biocompatible polymers with potential for hydrogel formation, but often require modification to meet demanding biomedical applications.

Purpose of the Study:

• To synthesize and characterize a novel thermoresponsive copolymer hydrogel based on sodium alginate grafted with poly(N-isopropylacrylamide) (Alg-g-PNIPAM) for 3D printing applications.
• To investigate the synergistic effects of methylcellulose (MC) and calcium ions (Ca2+) on the mechanical properties and printability of the Alg-g-PNIPAM hydrogel.
• To evaluate the in vitro biocompatibility and osteogenic potential of the developed hydrogels for bone tissue engineering.

Main Methods:

• Synthesis of sodium alginate-based copolymer grafted with thermoresponsive poly(N-isopropylacrylamide) (Alg-g-PNIPAM) chains.
• Formulation of hydrogels by combining Alg-g-PNIPAM with methylcellulose (MC) and crosslinking with calcium ions (Ca2+).
• Characterization of hydrogel mechanical properties, printability, stability, cell viability, and osteogenic differentiation using pre-osteoblastic cells.

Main Results:

• The addition of MC and Ca2+ significantly enhanced the mechanical properties of the Alg-g-PNIPAM hydrogel, achieving a storage modulus of approximately 1500 Pa at physiological temperatures.
• The developed hydrogels exhibited excellent print fidelity and stability, with minimal erosion (as low as 6% over seven days).
• Printed scaffolds demonstrated high cell viability (80%) and significantly promoted osteogenic differentiation, evidenced by increased alkaline phosphatase activity, calcium, and collagen production compared to controls.

Conclusions:

• The novel Alg-g-PNIPAM/MC hydrogel system, reinforced by dual crosslinking mechanisms, is suitable for 3D printing in biomedical applications, particularly bone tissue engineering.
• The enhanced mechanical strength, stability, and biocompatibility of these hydrogels support cell adhesion and promote osteogenic potential.
• This material represents a promising candidate for developing advanced scaffolds for bone regeneration therapies.