Polyelectrolyte nanogels decorated with monoclonal antibody for targeted drug delivery

Novel surface-functionalized cross-linked nanogels were developed as a platform to allow conjugation of monoclonal antibodies (mAb) for targeted drug delivery. Well-defined diblock copolymers of poly(ethylene glycol)-b- poly(methacrylic acid) (PEG-b-PMA) with PEG terminal aldehyde functionality were synthesized by atom transfer radical polymerization (ATRP) and characterized by GPC and ¹H NMR. These copolymers were used to prepare nanogels via condensation of PEG-b-PMA with Ca²⁺ ions into micelle-like aggregates, cross-linking of the PMA/Ca²⁺ cores and removal of Ca²⁺ ions. The resulting nanogels represent highly swollen spherical polyelectrolyte particles with free terminal aldehyde functionalities at the nonionic PEG chains. A reductive amination reaction between aldehyde groups and amino groups of mAb resulted in effective conjugation to the nanogels of mAb CC49 against tumor-associated glycoprotein 72 (TAG-72). The mAb retained the binding affinity to bovine submaxillary mucin after conjugation as shown by surface plasmon resonance (SPR). Therefore, aldehyde-functionalized nanogels can be linked to mAb using a simple, one-step approach. They may have potential for targeted delivery of diagnostic and therapeutic agents to tumors.