The self-assembly of a novel double hydrophilic block copolymer (DHBC) architecture is presented. By combining linear biomacromolecule pullulan with biocompatible poly(oligo(ethylene glycol) methyl ether) methacrylate) (P(OEGMA))-brush blocks via copper(I) catalyzed azide alkyne cycloaddition, a novel DHBC linear-brush combination is obtained. Self-assembly in water was observed via optical microscopy and dynamic light scattering (DLS). Moreover, DLS investigations showed that self-assembly efficiency significantly relies on the degree of polymerization of the brush-block. Furthermore, the self-assembly of the formed particles was investigated with cryogenic scanning electron microscopy (cryo-SEM). To preserve the aggregates at lower concentrations, a biocompatible and FDA approved cross-linking agent, namely, sodium trimetaphosphate (STMP), was utilized for cross-linking. The reaction of STMP and pullulan was followed by 31P NMR, while the presence of the cross-linking agent within the particles could be detected via the combination cryo-SEM and energy dispersive X-ray spectroscopy.