3D Confocal Laser Scanning Microscopy for Quantification of the Phase Behaviour in Agarose-MCC co-gels in Comparison to the Rheological Blending-law Analysis

The need for a rapid and direct alternative to the rheology-based blending laws in quantifying phase behaviour in biopolymer composite gels is explored in this study. In doing so, the efficacy of confocal laser scanning microscopy (CLSM) paired with image analysis software – FIJI and Imaris - in quantifying phase volume was studied. That was carried out in a model system of agarose with varying concentrations of microcrystalline cellulose (MCC) in comparison to the rheological blending laws. Structural studies performed using SEM, FTIR, differential scanning calorimetry and dynamic oscillation in-shear unveiled a continuous, weak agarose network supporting the hard, rod-shaped MCC inclusions where the composite gel strength increased with higher ‘filler’ concentration. The phase volumes of MCC, estimated with the microscopic protocol, matched the predictions obtained from computerized modelling using the Lewis-Nielsen blending laws. Results highlight the suitability of the microscopic protocol in estimating the water partition and effective phase volumes in the agarose-MCC composite gel.