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The anionic biomacromolecule, hyaluronic acid (HA), and cationic monomer, 2-(dimethylamino) ethyl methacrylate (DM), were used to construct an opposing charge polymer/monomer complex. Positively charged poly(2-(dimethylamino)ethyl methacrylate) (PDM) was prepared when DM monomers polymerized in aqueous solution. Self-assembly between PDM and HA was driven by electrostatic interaction, and HA/PDM complex colloid particles were formed in the aqueous medium. The HA/PDM complex structure was characterized by Fourier transform-infrared (FTIR) spectroscopy. The self-assembly behavior between HA and PDM, and the influence of polymerization time on HA/PDM complex colloid particle size, were investigated by dynamic laser scattering (DLS). Morphologies of the colloid particles were characterized by transmission electron microscopy (TEM). The influence of pH on the size and zeta potential of the colloid particles was investigated, and the emulsification of the colloid particles was preliminarily explored. The results showed that no HA/DM complex aggregates were formed before the polymerization of DM monomers. Spherical HA/PDM particles were spontaneously formed through electrostatic interaction between HA and PDM, coinciding with the gradual polymerization of DM. Particle sizes gradually decreased and stabilized with increasing polymerization time. The HA/PDM particles were pH sensitive and possessed improved emulsification properties compared with uncomplexed HA and PDM.

Self-assembled polymeric micelles can be used as efficient particulate emulsifiers. To explore the relationship between the structure and the oil-water interfacial behavior of the micelle emulsifiers, a new type of amphiphilic random copolymer, poly{(styrene-alt-maleic acid)-co-[styrene-alt-(N-3,4-dihydroxyphenylethyl-maleamic acid)]} (SMA-Dopa), was synthesized, self-assembled into micelles, and used as emulsifiers. SMA-Dopa was synthesized via an aminolysis reaction between dopamine and commercial alternating copolymer poly(styrene-alt-maleic anhydride) (SMA). Dopamine moiety facilitated the self-assembly of the SMA-Dopa in selective-solvent into stable micelles, and increased the adsorption of the SMA-Dopa at the oil-water interface. Additionally, the structural transition of the self-assembled SMA-Dopa52 micelles in response to pH and salinity changes were confirmed by means of TEM, AFM, DLS, aqueous electrophoresis techniques, potentiometric titration, and pyrene fluorescence probe methods. Micelles shrunk with increasing salinity, and flocculation of the shrunken primary micelles occurred at salt concentration exceeding 0.1 M. The micelles swelled with increasing pH, and the disassociation of the SMA-Dopa52 micelles occurred at pH above approximately 6.5. The structure of the micelles plays a crucial role in the oil-water interfacial performance. Micelles with various structures were used as emulsifiers to adsorb at the styrene-water and toluene-water interfaces. The emulsifying characteristics demonstrated that self-assembled SMA-Dopa52 micelles with moderately swollen structure (at 2pH6) combine the advantages of the solid particulate emulsifiers and polymeric surfactants, possessing excellent emulsifying efficiency and good emulsion stability. Moreover, the emulsifying performance of the SMA-Dopa52 micelles could be enhanced by the addition of salt.

The stepwise self-assembly of hollow plasmonic vesicles with vesicular membranes containing strings of gold nanoparticles (NPs) is reported. The formation of chain vesicles can be controlled by tuning the density of the polymer ligands on the surface of the gold NPs. The strong absorption of the chain vesicles in the near-infrared (NIR) region leads to a much higher efficiency in photoacoustic (PA) imaging than for non-chain vesicles. The chain vesicles were further employed for the encapsulation of drugs and the NIR light triggered release of payloads. This work not only offers a new platform for controlling the hierarchical self-assembly of NPs, but also demonstrates that the physical properties of the materials can be tailored by controlling the spatial arrangement of NPs within assemblies to achieve a better performance in biomedical applications.