Preparation and characterization of biomichical coaservate models with modified alginate and gelatin

Coacervates, one of the protocell models, are defined as self-organizing micro-sized membraneless microdrops produced by liquid-liquid phase separation and are considered as intermediate structures between living cells and inanimate structures. In the thesis study, new amphiphilic polymer derivatives (Amph-Alg and Amph-Gel) were synthesized by modifying two different hydrophilic polymers (Na-alginate and gelatin) with hydrophobic side groups (stearoyl chloride). These amphiphilic polymers were used to form stable coacervates without membranes that fold on their own. At the water-oil interface, hydrophobic parts were collected on the surface of the coacervates and hydrophilic parts were collected on the inner surface, allowing them to fold spontaneously. The internal skeleton system of the coacervates was formed by covalent amide bonds between Amph-Pol and poly(ethylene glycol) diamine, which was previously added to the fatty alcohol part, and thus stable coacervates were obtained. Long-term stability of the coacervates was achieved by using diamine/carbodiimide chemistry during coacervation. FTIR spectrum and Zeta potential of the modified polymers were recorded. Two narrow and sharp bands belonging to Amph-Alg formed at 2917 cm-1 and 2851 cm-1 in the FTIR spectrum confirmed the presence of hydrophobic side groups on the alginate. The amide bond formed in Amph-Gel was proven by the decrease in the intensity of the peak located at 2935 cm-1 during assembly. Zeta potential was measured as -43.3 mV for Amph-Alg and -30.1 mV for Amph-Gel. Dense coacervate droplets ranging in size from approximately 10 μm to 25 μm were observed under light, inverted and confocal microscopes. Coacervates were dried in a freeze dryer and SEM images were successfully taken. The size of the dry coacervates was concentrated between 5 μm and 10 μm. The obtained coacervates have important advantages such as being formed from biocompatible and economical polymers, being easily obtained by chemical reactions and having dimensions similar to the cell size. This makes them quite promising in terms of their future use in areas such as biomedicine, biotechnology, synthetic biology, and even food and cosmetics.