Comparison of different filler types as bioactive agents in Hydroxypropyl methylcellulose /Agarose composite

New materials play a crucial role in bone regeneration by providing biocompatible scaffolds that support cell adhesion, proliferation, and osteogenic differentiation. In the present work, we investigate the effect of three different fillers, seashell powder (SSP), nano-hydroxyapatite (nHA), and borate bioactive glass (BG), on the biophysical properties of Hydroxypropyl methylcellulose (HPMC)/Agarose (AG) polymeric matrix for bone tissue regeneration. The study identifies seashell powder's distinct fingerprint as a high-bioavailabe, sustainable substitute for bone regeneration in comparison with synthetic bioceramics, a comparison that hasn't been documented before. The composites were prepared using freeze- drying method and were characterized using dielectric spectroscopy (DS), Dynamic mechanical analysis (DMA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX), porosity and X-ray diffraction (XRD). The antimicrobial activities of the composites and cytotoxicity against Normal Human Skin Fibroblast were evaluated using MTT [3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) Assay. The results indicated that the permittivity (ε') of HPMC/Agarose is enhanced by compositing it with different fillers. The HPMC/AG/nHA composite exhibits the greatest values of ε'. In general, the addition of fillers enhanced dielectric performance by reducing losses, altering relaxation dynamics, and restricting chain mobility. Dynamic mechanical analysis revealed that filler loading reduces the mechanical damping factor (tan δ), which implies good interfacial adhesion, as confirmed by SEM. The weight loss of the reinforced composites in simulated body fluid after 28 days of immersion was 45.975, 67.427 and 41.7 for HPMC/AG/SSP, HPMC/AG/BG and HPMC/AG/nHA respectively. The in-vitro bioactivity of the filled composites was confirmed using FTIR, SEM, and EDX techniques. This could potentially enhance the composites' capacity to form bone in vivo. The porosity was in the range of 77-80%. The cell viability reached 91.59, 95.75, and 104.75% for HPMC/Agarose/BG, HPMC/AG/nHA, and HPMC/AG/SSP, respectively. HPMC/AG/BG composite showed antimicrobial activity with inhibition zone diameters of 14, 11 and 12 mm for Escherichia coli, Staphylococcus aureus, and Candida albicans respectively. The results support the manufactured composites' significant potential for use as materials for bone scaffolds. They Shed light on the seashells as a safe and bioactive natural resource, demonstrating performance comparable to bioactive glass and hydroxyapatite when used as a polymer reinforcer for bone tissue engineering applications.