Engineered microcapsules fabricated from reconstituted spider silk

The spider-silk protein C₁₆ was assembled at an oil/water interface to form a microcapsule with high mechanical stability by emulsifying an aqueous solution of C₁₆ with concentrations between 1-6 mg mL ^-1 in toluene. Microcarpules were transfreed into a continuous phase solution by adding an aqueous sublayer below toluene and transforming two-phase emulsion into a single-phase solution by adding ethanol to solubilize the water and toluene. The size of the microcapsules is controlled by adjusting the emulsion droplet size through changes in the emulsion shear rate to form silk capsules with diameter between 1 and 30 μm. Microcapsule formation follows an emergence of two shoulders in the adsorption spectra indicating a change in the secondary structure of C₁₆. The results show that spider-silk microcapsules have exceptional strength and tenacity, which leads to encapsulation of high concentrations of an active ingregredients.