Characterizing the Viscoelasticity of Calcium-Alginate Hydrogels Via Multiple Particle Tracking Microrheology

Pseudomonas aeruginosa is a biofilm-forming bacterium and an opportunistic human pathogen. These biofilms are highly adaptable and resistant to antimicrobial treatments, in part due to a heterogeneous intercellular matrix composition and superstructure. In recent work by others and ourselves, P. aeruginosa biofilms have been observed to incorporate substances, like collagen and calcium ions, that originate in the host environment. This can result in major alterations in the mechanical properties of the biofilm. In particular, another group has recently shown that calcium ions cross-link the matrix polymer alginate, creating a gel-like superstructure. In this work, I seek to use microrheology to characterize the viscoelastic properties of alginate hydrogels formed in the presence of biologically relevant concentrations of calcium ions as an in-vitro analog to alginate-dominant P. aeruginosa biofilms developing in a host environment containing calcium. Later, I intend to use microrheology to measure the effect of enzymatic treatment on such model "biofilms". The goal is to evaluate the efficacy of enzymes at disrupting the mechanics and microstructure of biofilms, and connect this to their possible roles in treating biofilm disease.