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Formation of alginate gel microparticles induced by calcium in aqueous electrolyte solution was characterized by cronoamperometry at the dropping mercury electrode, DME [1], circular dichroism, CD [2] and spectrophotometry. The sol-gel transition of alginate solutions in presence of divalent cations leads to a physical hydrogel (non-covalently crosslinked network) which is accompanied by a sharp change in CD spectra and a decreasing solution transparency. The transformation of alginate free polymers in a solution to microscopic gel particles, induced by the addition of calcium, was followed with DME through distinct differentiation of adsorption/adhesion electrochemical responses. The gel-like particles show a characteristic dip-shaped signal whose amplitude reflects the gel particle size while the dip signal frequency depends on gel particle concentration. In this study we present for the first time the electrical signals of alginate microgel particles that appear owing to their collision at the DME/aqueous electrolyte interface. The appearance of electrochemical signal in alginate gel dispersion is identical to electrochemical response of native microgel particles in seawater [3]. Alginate gels can be used as a model system for the characterisation of natural microparticles observed in the Northern Adriatic seawater and of their role in the aggregation processes and mucilage formation [4]. References: [1] R. Tsekov, S. Kovač, V. Žutić, Langmuir 15 (1999) 5649 [2] E. R. Morris, D.A. Rees, D. Thom, Carbohydr. Res. 81 (1980) 305 [3] "Project Jadran" Systematic study of the Adriatic Sea as a basis for sustainable development of the Republic Croatia” 1998 - [4] V. Žutić, V. Svetličić, Interfacial processes. In: P. Wangersky (Ed.) The Handbook of Environmental Chemistry, vol 5, 2000 |
