This article reports the synthesis of biohybrid nanogels by crosslinking six-arm acrylate functionalized star shaped P(EO-stat-PO) with the amine groups of various amino acids of a hen egg ovalbumin in W/O emulsion. PEG Poly(ethylene glycol)-diamines of different molecular weights (368.5 g/mol, 897.1 g/mol, 3000 g/mol, and 6000 g/mol) were used to optimize the crosslinking reactions in aqueous droplets. The increase of molecular weight of the PEG-diamine led to decrease of the nanogel size due to better stabilization by longer PEG chains. The size of the ovalbumin nanogels was independent of the acrylate-sP(EO-stat-PO):ovalbumin ratio in the reaction mixture. The bicinchoninic acid (BCA) assay proved that the ovalbumin has been effectively crosslinked by reactive prepolymers. From the results of BCA assay, it can also be established that there exists a limiting amount of ovalbumin which can be incorporated into the nanogels. Both Diamine and ovalbumin-based nanogels exhibit amphoteric behavior and display a positive charge in acidic and a negative charge in basic environment. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012