Temperature-Responsive Injectable Composite Hydrogels Based on Poly(N-Isopropylacrylamide), Chitosan, and...

Area of Science:

• Materials Science
• Biomedical Engineering
• Polymer Chemistry

Background:

• Injectable hydrogels offer minimally invasive delivery systems for various biomedical applications.
• Poly(N-Isopropylacrylamide) (PNIPAAm) and Chitosan are biocompatible polymers with tunable properties.
• Cellulose nanocrystals (CNCs) can enhance the mechanical and thermal properties of hydrogel networks.

Purpose of the Study:

• To fabricate injectable, temperature-responsive Poly(N-Isopropylacrylamide)/Chitosan composite hydrogels reinforced with cellulose nanocrystals (CNCs).
• To investigate the effect of CNC incorporation on the structural, mechanical, thermal, and swelling properties of the hydrogels.
• To evaluate the cytocompatibility of the developed composite hydrogels for potential biomedical use.

Main Methods:

• Photopolymerization was employed to synthesize PNIPAAm/Chitosan hydrogels with varying concentrations of CNCs (0.1-3% w/v).
• Fourier Transform Infrared (FT-IR) spectroscopy was used to confirm chemical structure.
• Rheology, thermogravimetric analysis (TGA), and swelling tests were performed to characterize material properties.
• In vitro cytotoxicity assays using Human Dermal Fibroblast adult (HDFa) cells were conducted.

Main Results:

• FT-IR confirmed the successful integration of PNIPAAm, Chitosan, and CNCs.
• CNC incorporation reduced pore size and enhanced mechanical properties (storage modulus G') above 30 °C.
• Thermogravimetric analysis indicated thermal stability up to 300 °C.
• Hydrogels exhibited volume phase transition temperatures (VPTTs) between 34-38 °C and increased equilibrium swelling ratios (ESR) with CNCs.
• In vitro studies demonstrated non-toxicity of the hydrogels to HDFa cells.

Conclusions:

• Injectable, thermo-responsive PNIPAAm/Chitosan composite hydrogels reinforced with CNCs were successfully fabricated.
• The addition of CNCs improved mechanical strength, thermal stability, and swelling properties while maintaining physiological VPTTs.
• The non-toxic nature of these composite hydrogels highlights their significant potential for diverse biomedical applications.