Design and Characterization of HEMA ‐Based 3D ‐Printed Hydrogel Networks for Optical Biomaterial Applications

ABSTRACT HEMA‐based hydrogels are promising biomaterials for biomedical and optical applications because of their tunable mechanical, optical, and biological properties. In this study, a series of 3D‐printable HEMA hydrogel networks were prepared using PEGDA (Mw: 700 Da) and EGDMA as crosslinkers, and their chemical, physical, mechanical, optical, rheological, and biological properties were systematically investigated. Mechanical analysis revealed that HEMA:EGDMA (1:0.5) exhibited the highest tensile strength (6.70 MPa) with limited elongation (4.14%), whereas HEMA:PEGDA (1:1) showed superior flexibility (31.21% elongation) but lower tensile strength (0.76 MPa). The contact angle measurements ranged from 36.1° to 74.2°, indicating enhanced hydrophilicity in PEGDA‐rich formulations and increased hydrophobicity with higher EGDMA content. Optical transmittance analysis showed that HEMA:EGDMA (1:0.5) achieved the highest clarity (93.5% at 600 nm), followed by HEMA:PEGDA (1:1) with 89.0%. Reflectance spectroscopy further demonstrated that both the crosslinker type and water content of the formulation critically affected the transparency and UV reflectance. The equilibrium water content (EWC) varied from 12% to 35%, depending on the formulation composition. Biocompatibility studies using MTT assays and immunofluorescence staining on HDF cells confirmed that all hydrogel networks maintained cell viability above 60% over 24, 48, and 72 h, supporting their potential for use in optical biomaterial applications.