Youngdo Jeong

Direct delivery of functional proteins and enzymes to the cytosol using nanoparticle-stabilized nanocapsules.

Intracellular protein delivery is an important tool for both therapeutic and fundamental applications. Effective protein delivery faces two major challenges: efficient cellular uptake and avoiding endosomal sequestration. We report here a general strategy for direct delivery of functional proteins to the cytosol using nanoparticle-stabilized capsules (NPSCs). These NPSCs are formed and stabilized through supramolecular interactions between the nanoparticle, the protein cargo, and the fatty acid capsule interior. The NPSCs are ~130 nm in diameter and feature low toxicity and excellent stability in serum. The effectiveness of these NPSCs as therapeutic protein carriers was demonstrated through the delivery of fully functional caspase-3 to HeLa cells with concomitant apoptosis. Analogous delivery of green fluorescent protein (GFP) confirmed cytosolic delivery as well as intracellular targeting of the delivered protein, demonstrating the utility of the system for both therapeutic and imaging applications.

Drug delivery using nanoparticle-stabilized nanocapsules.

Microcapsules (MCs) are versatile systems with applications in areas as diverse as microreactors, catalysis,[1] diagnostics and drug delivery.[2] In these systems self-assembly of lipids and/or polymers can be used to generate several types of nano- and micro- capsules. These include vesicular structures such as liposomes,[3] polymerosomes,[4] colloidosomes,[5] and polyelectrolyte capsules that feature aqueous interiors and exteriors.[6] An alternate motif is provided by emulsions, where additives are used to stabilize the interface between immiscible fluids to produce e.g. oil-in-water emulsions.[7] Through tailoring of the composition and structure of the building blocks MCs of both types can be engineered with well-defined structures, functions and stability.[8] MCs provide excellent delivery vehicles for biomedical applications, featuring high payload-to-carrier ratios and protection of encapsulated materials from degradation.

Colorimetric Protein Sensing Using Catalytically Amplified Sensor Arrays

Catalytically active iron oxide nanoparticles are used as recognition elements and signal amplifiers for the array-based colorimetric sensing of proteins. Interactions between cationic monolayers on the Fe(3) O(4) NPs and analyte proteins differentially modulates the peroxidase-like activity of Fe(3) O(4) NPs, affording catalytically amplified colorimetric signal patterns that enable the detection and identification of proteins at 50 nM.

Direct Fabrication of Functional and Biofunctional Nanostructures Through Reactive Imprinting

One-step reactive imprinting of a protected maleimide polymer provides a nanopatterned maleimide surface via a retro-Diels-Alder reaction. The patterned surfaces are used as scaffolds for the generation of functional and biofunctional structures. The biofunctional surface offers a platform for aligning the cells in the direction of patterns, demonstrating the potential for applications in the field of tissue engineering.

Co-delivery of protein and small molecule therapeutics using nanoparticle-stabilized nanocapsules.

Combination therapy employing proteins and small molecules provides access to synergistic treatment strategies. Co-delivery of these two payloads is challenging due to the divergent physicochemical properties of small molecule and protein cargos. Nanoparticle-stabilized nanocapsules (NPSCs) are promising for combination treatment strategies since they have the potential to deliver small molecule drugs and proteins simultaneously into the cytosol. In this study, we loaded paclitaxel into the hydrophobic core of the NPSC and self-assembled caspase-3 and nanoparticles on the capsule surface. The resulting combination NPSCs showed higher cytotoxicity than either of the single agent NPSCs, with synergistic action established using combination index values.

Immobilization and Stabilization of Lipase (CaLB) through Hierarchical Interfacial Assembly

Nanostructure-enabled hierarchical assembly holds promise for efficient biocatalyst immobilization for improved stability in bioprocessing. In this work we demonstrate the use of a hierarchical assembly immobilization strategy to enhance the physicochemical properties and stability of lipase B from Candida antarctica (CaLB). CaLB was complexed with iron oxide nanoparticles followed by interfacial assembly at the surface of an oil-in-water emulsion. Subsequent ring opening polymerization of the oil provided cross-linked microparticles that displayed an increase in catalytic efficiency when compared to the native enzyme and Novozym 435. The hierarchical immobilized enzyme assembly showed no leakage from the support in 50% acetonitrile and could be magnetically recovered across five cycles. Immobilized lipase exhibited enhanced thermal and pH stability, providing 72% activity retention after 24 h at 50 °C (pH 7.0) and 62% activity retention after 24 h at pH 3.0 (30 °C); conditions resulting in complete deactivation of the native lipase.

Fabrication of Multiresponsive Bioactive Nanocapsules through Orthogonal Self‐Assembly

Multifunctional self-assembled systems present platforms for fundamental research and practical applications as they provide tunability of structure, functionality, and stimuli responsiveness. Pragmatic structures for biological applications have multiple design requirements, including control of size, stability, and environmental response. Here we present the fabrication of multifunctional nanoparticle-stabilized capsules (NPSCs) by using a set of orthogonal supramolecular interactions. In these capsules, fluorescent proteins are attached to quantum dots through polyhistidine coordination. These anionic assemblies interact laterally with cationic gold nanoparticles that are anchored to the fatty acid core through guanidinium-carboxylate interactions. The lipophilic core then provides a reservoir for hydrophobic endosome-disrupting agents, thereby generating a system featuring stimuli-responsive release of a payload into the cytosol with fluorescence monitoring.

Characterization of surface ligands on functionalized magnetic nanoparticles using laser desorption/ionization mass spectrometry (LDI-MS)

Functionalized magnetic nanoparticles (MNPs) have been characterized by laser desorption/ionization mass spectrometry (LDI-MS). Quantitative information about surface ligand composition and structure for monolayer and mixed monolayer protected Fe3O4 and FePt NPs can be obtained rapidly with very little sample consumption.

Molecular Recognition Induced Self-Assembly of Diblock Copolymers: Microspheres to Vesicles

Random diblock copolymer scaffolds grafted with diamidopyridine (DAP) hydrogen bonding recognition units self-assembled to furnish microspheres when mixed with monoblock copolymers decorated with complementary recognition elements. Through choice of block length, microspheres of various sizes could be produced. The relative length of the two blocks plays a crucial role in determining the formation of aggregates. PEG-b-P(S-co-S(DAP)) diblock copolymer was used to fabricate recognition induced pegylated microspheres, by non-covalent crosslinking with monoblock copolymer functionalized with complementary thymine (Thy) units. These self-assembled microspheres can be efficiently crosslinked via photochemical [2pi(s) + 2pi(s)] cycloaddition with the resultant morphology change into vesicular structures.

Tunable Elastic Modulus of Nanoparticle Monolayer Films by Host–Guest Chemistry

The elastic modulus of an ultrathin nanoparticle (NP) monolayer film is tuned by modulating the binding strength between the NPs on a molecular level. NP monolayer films constructed by crosslinking NPs of different binding affinities are fabricated at oil/water interfaces. By inducing buckling patterns on these films, the correlation between the binding affinity of the NPs and the elastic modulus is investigated.