Study of Interfacial Rheology of Human Serum Albumin Microcapsules using Electrodeformation Technique

Abstract

Understanding the mechanical characterization of microcapsules is critical for their precise applications, such as in pharmaceuticals, cosmetics, agriculture, food industries, etc. Microcapsules synthesized from different materials show distinct mechanical characteristics. It is therefore necessary to study these systems considering their respective micro-physics for an exact theoretical model suitable to these systems. In the present work, we conducted mechanical characterization of the membrane of human serum albumin (HSA) microcapsules using the electrodeformation technique. Proteins are widely used as encapsulating materials for many biomedical and food industries. Relating the microstructure to the mechanical properties of a protein-membrane is a challenge owing to its complex structure and sensitivity towards different environmental conditions such as pH, temperature, and solvents. Interfacial rheology of human serum albumin microcapsules studied using the electrodeformation technique shows that HSA capsules are strain-softening in nature. The viscoelasto-electrohydrodynamic model was utilized to understand the creep mechanism in the human serum albumin capsules. The effect of different reaction parameters such as protein concentration and pH on the morphology of the capsule membrane was investigated, and an attempt has been made to correlate microstructure with the mechanical properties. The pH has a remarkable effect on the morphology of HSA microcapsules which is also reflected in their mechanical characteristics. The capsule synthesized with carbonate buffer shows very distinct morphology with pores on the membrane surface, making the membrane less elastic with significant nonrecoverable creep. The capsules synthesized with different protein concentrations at the same pH condition show different morphology and thus different rheological properties. Capsules with a low concentration of HSA show smooth membrane structure with higher Young's modulus than