Hydration is central to mitigating surface fouling by oil and microorganisms. Immobilization of hydrophilic polymers on surfaces promotes retention of water and a reduction of direct interactions with potential foulants. While conventional surface modification techniques are surface-specific, mussel-inspired adhesives based on dopamine effectively coat many types of surfaces and thus hold potential as a universal solution to surface modification. Here, we describe a facile, one-step surface modification strategy that affords hydrophilic, and underwater superoleophobic, coatings by the simultaneous deposition of polydopamine (PDA) with poly(methacryloyloxyethyl phosphorylcholine) (polyMPC). The resultant composite coating features enhanced hydrophilicity (i.e., water contact angle of ~10° in air) and antifouling performance relative to PDA coatings. PolyMPC affords control over coating thickness and surface roughness, and results in a nearly 10 fold reduction in Escherichia coli adhesion relative to unmodified glass. The substrate-independent nature of PDA coatings further promotes facile surface modification without tedious surface pretreatment, and offers a robust template for codepositing polyMPC to enhance biocompatibility, hydrophilicity and fouling resistance.

Functionalizable hydrogels are of great interest as three-dimensional (3D) scaffolds for cell growth and tissue engineering. The ability to covalently immobilize biologically relevant molecules with accurate control of their density within the hydrogel matrix is highly desirable. Dendron−polymer conjugates prepared via Huisgen type “click” reaction provides a unique precursor for reactive hydrogels. A family of dendron−polymer conjugates were prepared by coupling second- and third-generation alkyne appended polyester dendrons with linear poly(ethylene glycol) diazides, PEG2K and PEG6K. Controlled cross-linking of alkyne-functionalized dendron−polymer−dendron conjugates with a hydrophilic diazide provides hydrogels with gelation efficiencies greater than 80%. Excess leftover alkynes can be used to functionalize these hydrogels as desired. Fine tuning of degree of cross-linking and functionalization is demonstrated by immobilization of streptavidin.

Poly(ethylene glycol) methacrylate-based hydrogels containing thiol reactive maleimide functional groups have been synthesized using a novel Diels-Alder cycloaddition/cycloreversion-based strategy. Masked maleimide groups are directly incorporated into the hydrogel matrix during the gelation process by utilization of a furan protected maleimide containing methacrylate monomer. During the polymerization, the thermal deprotection of the maleimide groups in some of the monomer results in the formation of an in situ cross-linker that results in gelation. After gelation, the protected maleimide groups can be activated to their reactive forms via a thermal cycloreversion step. The efficiency of the gel formation, maleimide incorporation, and functionalization of the hydrogel were investigated. These reactive maleimide group embedded hydrogels can be efficiently derivatized with thiol containing molecules such as a fluorescent dye, BodipyC10SH. Thiolated biotin derivatives were covalently attached to these hydrogels under mild, reagent-free conditions. It was found that the extent of immobilization of FITC-streptavidin onto these biotinylated gels can be tailored by varying the density of maleimide groups in the parent hydrogels.

Nanoparticles (NPs) segregated to the liquid/liquid interface form disordered or liquid-like assemblies that show diffusive motions in the plane of the interface. As the areal density of NPs at the interface increases, the available interfacial area decreases, and the interfacial dynamics of the NP assemblies change when the NPs jam. Dynamics associated with jamming was investigated by X-ray photon correlation spectroscopy. Water-in-toluene emulsions, formed by a self-emulsification at the liquid/liquid interface and stabilized by ligand-capped CdSe-ZnS NPs, provided a simple, yet powerful platform, to investigate NP dynamics. In contrast to a single planar interface, these emulsions increased the number of NPs in the incident beam and decreased the absorption of X-rays in comparison to the same path length in pure water. A transition from diffusive to confined dynamics was manifested by intermittent dynamics, indicating a transition from a liquid-like to a jammed state.

A series of block copolymers based on 2-methacryloyloxyethyl phosphorylcholine (MPC) were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. Incorporation of dihydrolipoic acid (DHLA) into the hydrophobic block led to formation of block copolymer micelles in water. The micelles were between 15 and 30 nm in diameter, as characterized by dynamic light scattering (DLS), with some size control achieved by adjusting the hydrophobic/hydrophilic balance. Cross-linked micelles were prepared by disulfide formation, and observed to be stable in solution for weeks. The micelles proved amenable to disassembly when treated with a reducing agent, such as dithiothreitol (DTT), and represent a potential delivery platform for chemotherapeutic agents. As a proof-of-concept, camptothecin (CPT) was conjugated to the polymer scaffold through a disulfide linkage, and release of the drug from the micelle was monitored by fluorescence spectroscopy. These CPT-loaded prodrug micelles showed a reduction in release rate compared to physically encapsulated CPT. The use of disulfide conjugation facilitated drug release under reducing conditions, with a half-life (t1/2) of 5.5 hours in the presence of 3 mM DTT, compared to 28 hours in PBS. The toxicity of the micellar prodrugs was evaluated in cell culture against human breast (MCF7) and colorectal (COLO205) cancer cell lines.