Block Copolymer Robustness and Stability of Templated Protein Nanocomposites

Therapeutic proteins have high specificity and activity making them therapeutically valuable but a low level of protein stability in solution leads to degradation. The templated BSA remains in its native state both in secondary structure and in hydrodynamic diameter when dispersed into the cubic-packed spherical micelle phase of a PluronicRTM block copolymer. Templating the bovine serum albumin (BSA) into the interstitial spaces of block copolymer micelle phase can increase the shelf life of BSA at 25°C. Colloidal aggregation of BSA is hindered when the BSA is templated into the cubic-packed spherical micelle phase of the block copolymer gel. The templated BSA shows increased stability inside the interstitial spaces of the block copolymer over an aqueous solution of BSA at 25°C after six months. The nanoscale structure of the block copolymer is unaffected by denaturation of templated BSA.;The robustness of the PluronicRTM block copolymers is analyzed. The PluronicRTM P123 block copolymer forms a cubic-packed spherical micelle phase and a hexagonally-packed cylindrical micelle phase and it is proposed that the observed anisotropic order-order transition is caused by the cubic-packed spherical micelle phase persisting into the hexagonally-packed cylindrical micelle phase due to the hindrance of rearranging the spherical micelles into cylindrical micelles and then packing of the cylindrical micelles into a hexagonally-packed cylindrical micelle phase. PluronicRTM block copolymers and nanocomposites are effectively aligned from a multi-domain "powder" to a macro-domain "single crystal" under steady shear or oscillatory flow. A larger amount of the volume fraction remains in the randomly oriented multi-domain "powder" under high shear for the nanocomposites than for the block copolymer. Less of the volume fraction remains in the randomly oriented multi-domain "powder" under high oscillation for the nanocomposites compared to the block copolymer. The type of oscillation waveform has an effect on the crystal lattice of the block copolymers and a block copolymer with a random-close packed (RCP) crystal lattice under oscillation with a triangular wave form is shown to form a face-centered cubic (FCC) crystal lattice under oscillation with a sinusoidal wave form.