Described herein are bioresponsive protein polymers for therapeutic applications, including delivery to physiologically demanding environments, such as the eye surface. Bioresponsive protein polymers can be fused with biopharmaceuticals using genetic engineering techniques for enhanced therapeutic activity. In certain embodiments, the unique temperature-sensitive phase separation properties of bioresponsive protein polymers, allows generation of therapeutics resistant to ocular clearance. Such fusion proteins containing bioresponsive protein polymers and biopharmaceuticals allow retention of drugs in the eye for much longer periods of time. Improved biostability and bioavailability improves drug efficacy, while reducing cost and eliminating the need for repeated drug application
