Block ionomer complexes (BICs) are an assembly of block-copolymers that electrostatically interact with an oppositely-charged polyelectrolyte, forming a core-shell structure that resembles a micelle. In our study, carboxymethyl-dextran (CMD) and carboxymethyl-dextran-block-poly(ethylene glycol) (CMD-b-PEG) were successfully prepared from dextran and/or poly(ethylene glycol) using an established protocol and confirmed by nuclear magnetic resonance spectroscopy (NMR). BIC formation between CMD-b-PEG and alpha-lactalbumin (a-lac) was investigated following acid titration, while traditional electrostatic complexes were formed between CMD and a-lac as a control. The successful assembling between a-lac and CMD or CMD-b-PEG with different molar ratios was confirmed through turbidity, light scattering, zeta-potential, and transmission electron microscopy measurements. Scattering intensity measurements indicated that complex formation between a-lac and CMD-b-PEG occurred at higher pH values than complexes of a-lac and CMD. Electron micrographs confirmed a-lac and CMD-b-PEG complex formation with typical radii of 20-50 nm, which agreed with results from dynamic light scattering. Visible light turbidimetry measurement showed that the molar ratio of a-lac and CMD-b-PEG did not significantly impact critical pH values of phase-separation, unlike complexes of a-lac and CMD, which was attributed to the presence of the poly(ethylene glycol) block. This system shows promise for utilization as a biopolymer-based controlled delivery vehicle for bioactive compounds.

Block ionomer complexes formed by carboxymethyl-dextran-block-poly(ethylene glycol) copolymer and α-lactalbumin

249th National Meeting (2015)

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