A method of controlling a physical characteristic of polymeric nanocarrier-encapsulated protein particles includes altering or selecting a weight percentage of a hydrophobic polymer block in a total amphiphilic diblock copolymer of a primary emulsion of a double emulsion, freeze-thaw technique. The primary emulsion is formed using a freeze-thaw cycle of the amphiphilic diblock copolymer and a protein having a molecular weight of up to or equal to 300,000 Da. Selection of the hydrophobic polymer block percentage alters one or more characteristics of the resulting nanoparticles, such as shape. Thus, as one aspect, a method of producing filamentous polymeric nanocarrier-encapsulated protein (i.e., active enzyme) particles involves forming a primary emulsion using a freeze-thaw cycle of (i) an amphiphilic diblock copolymer, which has a molecular weight of about 10,000 to about 100,000 Da and comprises a conjugate of the hydrophobic polymer block and a hydrophilic polymer block, wherein the amphiphilic diblock copolymer comprises greater than 81% to about 95% by weight of the hydrophobic polymer block; and a protein having a molecular weight of up to or equal to about 300,000 Da. Various compositions comprising such filamentous-shaped nanocarrier particles, and methods of use for diagnosis and therapy are disclosed.