| abstract |
A composition that expands or contracts upon a change in exposure to light energy is provided that comprises a protein or protein-based polymeric material having an inverse temperature transition in the range of liquid water, wherein at least a fraction of the monomers in the polymer contain an light energy-responsive group that undergoes a change in hydrophobicity or polarity upon a change in exposure to light energy and is present in an amount sufficient to provide a shift in the inverse temperature transition of the polymer upon the change in exposure to light energy. Compositions of the invention, including those further containing a side-chain chemical couple, can be used in a variety of different applications to produce mechanical work, cause turbidity changes, cause chemical changes in an enclosed environment, or transduce other free energies by varying the exposure to light energy on the composition. The degree and efficiency of mechanical or chemical change can be controlled by, inter alia, selection of the type, amount, position, and mole fraction of the light energy-responsive side chain group and hydrophobic residues in the polymer. |