Viscoelasticity of multi-armed PEG hydrogels by tweezers-based opto-microrheometry*

Hydrogels, like extracellular materials, possess both solid and liquid-like properties; if their mechanical properties can be tailored precisely, they can be used not only to understand how cells respond to an extracellular environment but also for designing engineered tissues. However, multiple parameters that can dictate the viscoelastic properties of hydrogels are complex, it is difficult to predict mechanical properties of hydrogels simply from their molecular structures. To this end, an oscillating optical tweezer-based opto-rheometer is used to measure the micro viscoelasticity of an eight-armed PEG-DBCO covalently cross-linked with PAN MMP. Dependence of the viscoelasticity on the polymer concentration is measured. Viscoelasticity data is analyzed using the Maxwell model to examine how relaxation times and high-frequency shear modulus depend on the polymer concentration.