The optimum condition of acid hydrolysis for hydroxyapatite extraction from bigeye snapper (Priancanthus tayenus) bone and the effects of extraction time (10–60 min) and HCl concentration (2.0–5.0% w/v) on yield and hydroxyapatite properties were determined. The optimum extracted condition was found using 5% HCl for 60 min, which was 13.4% yield; 19.8 g/100 g Ca content; 9.6 g/100 g P content; 2.1 Ca/P ratio; L*, a*, b*; and ΔE as 84.5, 2.8, 16.5, and 15.6, respectively. The using of 5% NaOH solution was optimum for hydroxyapatite precipitation from the extracted solution. The characteristic and biological properties of the obtained hydroxyapatite were studied. Fourier transform infrared spectroscopy and X-ray diffraction results showed a good comparison between the extracted and commercial hydroxyapatite. The microstructure of the extracted hydroxyapatite from a scanning electron microscope showed an irregular and flat-plate shape, large surface area, and roughness. The extracted hydroxyapatite was non- and low-cytotoxicity at a concentration of 50 and 100–400 µg/mL, respectively. Bovine serum albumin (BSA) adsorption and desorption of hydroxyapatite was studied. An increasing BSA concentration, hydroxyapatite amount, and adsorption time significantly increased protein adsorption on hydroxyapatite. Protein desorption from BSA-loaded hydroxyapatite showed an increase of release initially in the first 4 days and became a steady release rate until 14 days.

Bacterial cellulose (BC) is highly valued for biomedical and industrial applications due to its exceptional biocompatibility, strength, and biodegradability. Polyvinyl alcohol (PVA) exhibits favorable characteristics, making it an ideal candidate for hydrogel formulation. In this study, BC–PVA composite hydrogels were synthesized by dissolving 1% w/w BC in ZnCl₂ 3H₂O and 10% w/w PVA in ZnCl₂nH₂O, n = 6, 9, 12, and 15. These solutions were combined at BC:PVA weight ratios of 3:1, 1:1, and 1:3, then crosslinking using a glutaraldehyde–acetone solution before immersion in deionized water. The resulting hydrogels exhibited a dense, tightly packed structure with mild to moderate porosity. FTIR analysis confirmed molecular interactions via a broad, reduced O–H stretching band and the appearance of C-H bending vibrations. The water content and swelling ratio ranged from 88.13% to 94.67% and 437.93% to 997.22%, respectively. At a compressive strain of 30%, the compressive strength ranged from 62.28 kPa to 93.16 kPa. This work introduces a novel and efficient method for preparing BC-PVA hydrogels using ZnCl₂ hydrate solvents. Both the ZnCl₂ hydration level and the BC:PVA ratio significantly influenced the structural, water content, swelling, and mechanical properties, offering tunable materials for biomedical or industrial applications.

Bacterial cellulose (BC) is a highly pure biomaterial that can be produced from agro-industrial residues, making it a sustainable candidate for tissue engineering applications such as biocompatible hydrogel. However, pure BC is rigid and brittle, which limits its clinical handling. This study aimed to synthesise BC membranes from the non-photosynthetic bacterium Komagataeibacter nataicola (TISTR 975) using mature coconut water as the primary fermentation medium, and to improve its mechanical properties by forming an in situ composite hydrogel with polyhydroxyalkanoate (PHA). Sucrose concentration and cultivation period were systematically varied and analysed using response surface methodology (RSM), which identified the optimal condition as a 7-day cultivation at 50 g/L sucrose, yielding a highly uniform membrane with the best structural integrity. In situ fabrication of the BC/PHA composite, achieved by dispersing PHA powder in the culture medium during synthesis, markedly enhanced the material’s flexibility and water-holding capacity. The elongation at break increased from 22.9% for pure BC to 28.2% for the composite, with only a slight reduction in ultimate tensile strength. A cradle-to-gate life cycle assessment (LCA) showed that the BC/PHA membrane had a global warming potential approximately 3.2 times lower than that of bovine collagen membranes, while the incorporation of PHA introduced a negligible additional environmental burden. These findings indicate that the locally producible and biodegradable BC/PHA composite hydrogel offers a favourable balance between mechanical performance, water-holding capacity, and environmental sustainability, positioning it as a promising candidate for the future development of guided tissue regeneration (GTR) gel membranes in dentistry.