A process for forming a conjugate between a bioresponsive molecule and at least one polymer chain under biologically compatible conditions, the process comprising: polymerizing radically polymerizable monomers at a temperature of between 4°C and 50°C by a grafting from approach using atom transfer radical polymerization (ATRP) in the presence of an aqueous system comprising: a bioresponsive molecule having at least one site specific functional initiator comprising a radically transferable atom or group, wherein the bioresponsive molecule is a protein; a transition metal that participates in a reversible reduction-oxidation cycle with at least one of the site specific functional initiator(s) and a dormant polymer chain(s) having a radically transferable atom or group, wherein the transition metal is copper, wherein the transition metal has a total concentration in the system of less than 1000 ppm to a lower value of 1 ppm; and a ligand that forms a stable complex with the transition metal catalyst, wherein the aqueous system comprises less than 30% by weight of organic solvent and monomer concentration and the total bioresponsive molecule concentration is less than 3 mg/mL, continuously reducing the transition metal, wherein the mole fraction of transition metal in a lower, activator oxidation state to transition metal in a higher, deactivator oxidation state is maintained during the polymerizing to be less than 20% by controlled addition of a reducing agent or by application of a potentiometric or galvanostatic charge; and forming a conjugate between the bioresponsive molecule and the at least one polymer chain, wherein the at least one polymer chain has a dispersity of less than 1.20. polymerizing radically polymerizable monomers at a temperature of between 4°C and 50°C by a grafting from approach using atom transfer radical polymerization (ATRP) in the presence of an aqueous system comprising: a bioresponsive molecule having at least one site specific functional initiator comprising a radically transferable atom or group, wherein the bioresponsive molecule is a protein; a transition metal that participates in a reversible reduction-oxidation cycle with at least one of the site specific functional initiator(s) and a dormant polymer chain(s) having a radically transferable atom or group, wherein the transition metal is copper, wherein the transition metal has a total concentration in the system of less than 1000 ppm to a lower value of 1 ppm; and a ligand that forms a stable complex with the transition metal catalyst, wherein the aqueous system comprises less than 30% by weight of organic solvent and monomer concentration and the total bioresponsive molecule concentration is less than 3 mg/mL, a bioresponsive molecule having at least one site specific functional initiator comprising a radically transferable atom or group, wherein the bioresponsive molecule is a protein; a transition metal that participates in a reversible reduction-oxidation cycle with at least one of the site specific functional initiator(s) and a dormant polymer chain(s) having a radically transferable atom or group, wherein the transition metal is copper, wherein the transition metal has a total concentration in the system of less than 1000 ppm to a lower value of 1 ppm; and a ligand that forms a stable complex with the transition metal catalyst, wherein the aqueous system comprises less than 30% by weight of organic solvent and monomer concentration and the total bioresponsive molecule concentration is less than 3 mg/mL, continuously reducing the transition metal, wherein the mole fraction of transition metal in a lower, activator oxidation state to transition metal in a higher, deactivator oxidation state is maintained during the polymerizing to be less than 20% by controlled addition of a reducing agent or by application of a potentiometric or galvanostatic charge; and forming a conjugate between the bioresponsive molecule and the at least one polymer chain, wherein the at least one polymer chain has a dispersity of less than 1.20.