Extraction, characterization and optimization of marine algal-derived hydrogels for three-dimensional biomaterials

Abstract

Marine algae are valuable sources of polysaccharides with wide ranging applications in biomaterial development. In the present study, four marine algae species, Kappaphycus alvarezii, Sargassum spp. (two species), and Turbinaria conoides were selected for evaluation as potential biomaterial sources. Identification of the algal species was made using morphological characteristics and molecular barcoding using ITS primers. Algal polysaccharides were extracted using the hot alkaline extraction method. Carrageenan was extracted from the red alga K. alvarezii with a high yield of 51.78%. Alginate was extracted from the brown algae with a yield weight of 42.65% and 42.59% from the two Sargassum spp. and T. conoides respectively. The chemical composition of the polysaccharide extracts was confirmed by fourier transform infrared (FTIR) spectroscopy, revealing characteristic sulphate ester peaks in carrageenan and guluronic and mannuronic acids in alginate. Optimization studies were conducted to enhance the properties of hydrogel formation. Parameters relevant to gelation properties were evaluated including solubility, gelation capacity and time, calcium chloride concentration, pH stability, swelling ratio, turbidity and melting and freezing temperatures. Optimum hydrogel formulations were achieved with 1.0 M CaCl2 in carrageenan 2% (w/v) and with 0.5 M CaCl2 in alginate 1% (w/v). The optimized hydrogel formulation combined high gel strength, low turbidity, stable swelling behaviour, and thermal stability suitable for physiological conditions. The materials produced in this study present a promising, sustainable, and biocompatible platform for future applications in biomedical engineering and advanced three-dimensional cell culture systems.