Hyun Ouk Kim

Hyaluronic acid receptor-targetable imidazolized nanovectors for induction of gastric cancer cell death by RNA interference

We have developed a nanovector consisting of hyaluronic acid (HA) and poly-L-lysine-graft-imidazole (PLI)-based polyplexes containing Bcl-xL-specific shRNA-encoding plasmid DNA (HA/PLI/pDNA) for CD44 targeted gastric cancer therapy. The prepared ternary polyplexes have a negative surface charge of -24 mV and a size of approximately 100 nm at an N/P ratio of 5 with HA/PLI molar ratio of 0.03. Gel electrophoresis and cell viability experiments demonstrated that the ternary polyplexes showed high stability and no cytotoxicity due to the anchored HA molecules on the surface of PLI/pDNA binary polyplexes. Selective cancer cell death was achieved by CD44-mediated gene delivery and the internalized gene was effectively escaped from endosomes due to the buffering capacity of imidazole groups in an acidic environment. These nanovectors may be highly efficient gene delivery tools that allow the selective destruction of metastatic gastric cancer cells.

Aptamer-conjugated gold nanorod for photothermal ablation of epidermal growth factor receptor-overexpressed epithelial cancer.

Abstract. Biomarker-specific photothermal nanoparticles that can efficiently sense markers that are overexpressed in distinguished adenocarcinomas have attracted much interest in an aspect of efficacy increase of cancer treatment. We demonstrated a promising prospect of a smart photothermal therapy agent employing anti-epidermal growth factor receptor aptamer (AptEGFR)-conjugated polyethylene glycol (PEG) layted gold nanorods (AptEGFR-PGNRs). The cetyltrimethylammonium bromide bilayer on GNRs was replaced with heterobifunctional PEG (COOH-PEG-SH) not only to serve as a biocompatible stabilizer and but also to conjugate AptEGFR. Subsequently, to direct photothermal therapy agent toward epithelial cancer cells, the carboxylated PEGylated GNRs (PGNRs) were further functionalized with AptEGFR using carbodiimide chemistry. Then, to assess the potential as biomarker-specific photothermal therapy agent of synthesized AptEGFR-PGNRs, the optical properties, biocompatibility, colloidal stability, binding affinity, and epicellial cancer cell killing efficacy in vitro/in vivo under near-infrared laser irradiation were investigated. As a result, AptEGFR-PGNRs exhibit excellent tumor targeting ability and feasibility of effective photothermal ablation cancer therapy.

Colourimetric redox-polyaniline nanoindicator for in situ vesicular trafficking of intracellular transport

Vesicular pH modulates the function of many organelles and plays a pivotal role in cell metabolism processes such as proliferation and apoptosis. Here, we introduce a simple colorimetric redox-polyaniline nanoindicator, which can detect and quantify a broader biogenic pH range with superior sensitivity compared to pre-established trafficking agents employing one-dimensional turn-on of the fluorescence resonance-energy-transfer (FRET) signal. We fabricated polyaniline-based nanoprobes, which exhibited convertible transition states according to the proton levels, as an in situ indicator of vesicular transport pH. Silica-coated Fe3O4-MnO heterometal nanoparticles were synthesised and utilised as a metal oxidant to polymerise the aniline monomer. Finally, silica-coated polyaniline nanoparticles with adsorbed cyanine dye fluorophores Cy3 and Cy7 (FPSNICy3 and FPSNICy7) were fabricated as proton-sensitive nanoindicators. Owing to the selective quenching induced by the local pH variations of vesicular transport, FPSNICy3 and FPSNICy7 demonstrated excellent intracellular trafficking and provided sensitive optical indication of minute proton levels.

Anchored protease-activatable polymersomes for molecular diagnostics of metastatic cancer cells

Real-time quantitative and qualitative analyses of metastasis-associated proteases are critical for precise diagnosis and novel therapeutic treatment of advanced cancers. However, conventional methods based on DNA, peptides, and proteins require sophisticated chemistry and additional processes to expose detection moieties, and they lack elements of temporal control, which limit their applicability. We designed unique protease-activatable polymersomes (PeptiSomes) for high sensitivity, in situ quantitative analysis of activating membrane-type 1 matrix metalloproteinases (MT1-MMP, MMP14). To do this, we first synthesized an amphiphilic block polymer-peptide and a copolypeptide based on mPEG-b-pLeu and MT1-peptide-b-pLeu, respectively. Amphiphilic self-assembled PeptiSomes in water were capable of disassembling and releasing the encapsulated self-quenched fluorescence dye (calcein) via enzymatic activation by MT1-MMP. Our PeptiSome system may potentially prevent the initiation and progression of cancer metastasis. Furthermore, the PeptiSome approach described here is likely to facilitate the development of rapid protease assay techniques and further extend the role of proteases as metastasis indicators and therapeutic targets.

Pseudo metal generation via catalytic oxidative polymerization on the surface of reactive template for redox switched off–on photothermal therapy

The integration of contrast-enhanced diagnostic imaging and therapy could utilize image guided therapy to plan treatment strategy. Toward this goal, a unique construction and operation of a pseudo metal based photothermal therapeutic agent (PPAM) is introduced by polyaniline (PANI) generation templated on iron oxide metal nanoclusters (MNCs). Notably, MNC core interferes as a catalytic agent and enables aniline polymerization under ambient acidic conditions. The intrusion of transition metal enhanced the proton sensitivity of PANI, which led to pH responsive conversion even at dilute proton concentrations (pH 5, 6) compared to the PANI particles prepared by conventional methods. Under physiological pH, PPAM reveals no special features; however, under low pH conditions, which is a notable characteristic of the cancer microenvironment, PPAM automatically converts into its emeraldine salt (ES) state and thus activates as a photothermal therapeutic agent. Utilizing this specific redox responsive switched off-on behavior of PPAM, precise and systemized photothermal therapy is demonstrated, proving itself as a smart and efficient photothermal therapeutic agent.

Stent containing CD44-targeting polymeric prodrug nanoparticles that release paclitaxel and gemcitabine in a time interval-controlled manner for synergistic human biliary cancer therapy

The use of drug-eluting stents (DESs) is a promising strategy for non-vascular diseases, especially human biliary cancer. However, the implementation of DESs suffers from two major obstacles: the side effects of drugs and the difficulty of controlling the drug release. These problems can be overcome if the stent elutes targeting nanoparticles that release drugs at time intervals that are dictated by the mechanisms of those drugs. We designed temporally controlled polymeric multi-prodrug nanoparticles (TCMPNs) that can be eluted from stents comprising polyurethane (PU) nanofiber as a polymeric matrix and paclitaxel (PTX)-loaded, CD44-targeting, hyaluronic acid-conjugated poly(lactic-co-glycolic acid) and gemcitabine (GEM) (P-H-G). TCMPNs enable two different types of drugs to be released temporally; PTX is released first owing to the collapse of the structure in the endosomes, and GEM, which induces synergistic anticancer activities, is hydrolyzed from P-H-G later in response to low pH. Embedded in the PU nanofiber, the TCMPNs demonstrate low initial burst behavior and sustainable release of the prodrug in vitro. Furthermore, TCMPN-eluting stents (TESs) exhibit continuous synergistic efficacy as available targeted cellular uptake prodrug delivery systems in tumor-bearing mice. These results demonstrate that this technology will open up cancer therapy by combining localized delivery and functional multi-drug-loaded nanoparticles.

Serially Ordered Magnetization of Nanoclusters via Control of Various Transition Metal Dopants for the Multifractionation of Cells in Microfluidic Magnetophoresis Devices

A novel method (i.e., continuous magnetic cell separation in a microfluidic channel) is demonstrated to be capable of inducing multifractionation of mixed cell suspensions into multiple outlet fractions. Here, multicomponent cell separation is performed with three different distinguishable magnetic nanoclusters (MnFe2O4, Fe3O4, and CoFe2O4), which are tagged on A431 cells. Because of their mass magnetizations, which can be ideally altered by doping with magnetic atom compositions (Mn, Fe, and Co), the trajectories of cells with each magnetic nanocluster in a flow are shown to be distinct when dragged under the same external magnetic field; the rest of the magnetic characteristics of the nanoclusters are identically fixed. This proof of concept study, which utilizes the magnetization-controlled nanoclusters (NCs), suggests that precise and effective multifractionation is achievable with high-throughput and systematic accuracy for dynamic cell separation.