Sangyeul Hwang

IMRA America, Inc., Ann Arbor, MI · NanoBio

Magnetic nanoparticles (MNPs) have potential for enhancing drug delivery in selected cancer patients, including those which have cells that have disseminated within cerebrospinal fluid (CSF) pathways. Here, we present data related to the creation and in vitro use of new two-part MNPs consisting of magnetic gold-iron alloy cores which have streptavi...

Magnetic Janus particles (MJPs) have received considerable attention for their rich assembly behavior and their potential technological role in applications ranging from simple magnetophoretic displays to smart cloaking devices. However, further progress is hampered by the lack of predictive understanding of the cooperative self‐assembly behavior o...

Medulloblastoma cells notoriously disseminate within CSF pathways. Magnetic nanoparticles (MNPs) have potential for enhancing delivery of chemotherapy to these cells. To date, successful clinical use of MNPs within CSF has been hampered due to the limited capacity for targeting at human-sized distances, and choice of the therapeutic component. Here...

Background: Magnetic nanoparticles (MNPs) have potential for enhancing drug delivery in selected cancer patients. To date, successful clinical use of MNPs has been limited due to the: 1) limited capacity for targeting at human-sized distances, 2) route of delivery, and 3) choice of therapeutic component. Here, we present data related to the creatio...

Although the functionalization of magnetic nanoparticles (MNPs) with biomolecules has been widely explored for various biological applications, achieving efficient bio-conjugations with a wide range of biomolecules through a single, universal and versatile platform remains a challenge, which may significantly impact their applications’ outcomes. He...

BACKGROUND: Medulloblastoma cells notoriously disseminate within CSF pathways. Magnetic nanoparticles (MNPs) have potential for enhancing delivery of chemotherapy to these cells. Successful clinical use of MNPs within CSF has been hampered due to limited capacity for targeting at human-sized distances, and choice of therapeutic component. Here, we...

Selective growth of metal organic framework materials on the surface of compartmentalized polymer microparticles is achieved by electrohydrodynamic co-jetting, selective surface modification, and anisotropic crystal growth.

Inorganic Janus particles are prepared by electro-hydrodynamic (EHD) co-jetting of mixtures of organic polymers and inorganic precursors and are converted into inorganic particles by thermal calcination. Using this approach, bicompartmental SiO2 particles with iron oxide nanocrystals selectively loaded into one hemisphere are created. Moreover, bic...

On-demand degradable polymer particles are fabricated via electrospraying of a solution of acetal-protected dextran that further includes 2-(4-methoxystyryl)-4,6-bis(trichloromethyl)-1,3,5-triazine as a photoacid generator. The illumination of UV light gives rise to photoacid and activates the catalytic deprotection of hydroxyl groups of dextran, l...

Herein, we report a novel jetting procedure that combines co-axial jetting used in the past to create core/shell fibers and particles with electrohydrodynamic co-jetting. This approach can result in Janus-core and shell fibers, where the Janus core is defined by the parallel center jets. A PLGA shell serves as a sacrificial virtual channel, which s...

We report the preparation of different shaped and sized magnetic Janus particles (MJPs) using electrohydrodynamic (EHD) co-jetting. Spherical MJPs with 20 µm sizes in diameter are directly prepared by the EHD co-jetting. The MJPs are composed of poly(lactic-co-glycolic acid) (PLGA) in both compartments, where one compartment has magnetite (28nm in...

My research is situated in between the biological and material sciences, where a variety of functional materials from small molecules to micron-sized polymeric fibers have been prepared. Such diverse materials have different functions depending on their sizes. Therefore, it is categorized into four different groups; molecules, polymers, particles,...

Bicompartmental composite nanoparticles are prepared by electryhydrodyanimic co-jetting with an organic-soluble polymer and titanium precursor, followed by a calcination step to convert the composite particles into stable Janus catalysts. The Janus catalysts retains the original shape and bicompartmental character. Selective growth of carbon nanotu...

Nature's particles, such as spores, viruses or cells, are adaptive-i.e., they can rapidly alter major phenomenological attributes such as shape, size, or curvature in response to environmental changes. Prominent examples include the hydration-mediated opening of ice plant seeds, actuation of pine cones, or the ingenious snapping mechanism of predat...

Janus particles with differentially degradable compartments were prepared by electrohydrodynamic (EHD) co-jetting and subsequent controlled crosslinking. These bicompartmental particles are composed of an interpenetrating polymer network of poly(ethylene oxide) and poly(acrylamide-co-acrylic acid) in one hemisphere and a crosslinked copolymer of de...

We, herein, introduce preparations of various types of magnetic Janus particles (MJPs) with different sizes and chemical components by means of the electrohydrodynamic (EHD) co-jetting, which has been recently known for producing multi-compartmentalized particles. Two distinctive polymers, a water soluble poly(acrylamide-co-acrylic acid) (p(AAM-co-...

We demonstrate spatially controlled photoreactions within bicompartmental microparticles and microfibers. Selective photoreactions are achieved by anisotropic incorporation of photocrosslinkable poly(vinyl cinnamate) in one compartment of either colloids or microfibers. Prior to photoreaction, bicompartmental particles, and fibers were prepared by...

Micro/nano-sized magnetic Janus particles (MJPs) are potentially useful in areas of display, sensor, tunable viscosity liquid, drug delivery, and separation. The prerequisites of those applications include the precise preparation and controllability of desired MJPs, of which shape and size, as well as compartmentalization can affect magnetic respon...

Janus particles possessing different optical, magnetic, and surface chemistry and morphological characteristics are interesting in a number of areas including display, imaging, sensing, catalyst, smart surface, and rheological fluid applications. Current challenges are related to the creation of spatially controlled functionalities as well as the l...

Electrohydrodynamic co-jetting of two different nanocrystal suspensions can result in anisotropic nanocomposite particles. Using this approach, we are able to prepare submicron-sized, spherical Janus particles (464 ± 242 nm), which are not only comprised of two chemically distinct compartments, but are also morphologically anisotropic. Specifically...

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Polymer particles with micro‐ and nanoscale anisotropy have received increasing interest for their ability to simultaneously present different physical‐ and chemical properties. In this communication, we demonstrate that gold nanocrystals (NCs) can be selectively incorporated into one compartment of anisotropic polymer particles. Stable bicompartme...

The preparation and characterization of a commercial biomedical-grade polyurethane (Tecophilic((R)), SP-93A-100) material possessing covalently linked copper(II)-cyclen moieties as a nitric oxide (NO) generating polymer are described. Chemiluminescence NO measurements demonstrate that the prepared polymer can decompose endogenous S-nitrosothiols (R...

An organoditelluride (RTeTeR) species (5,5 0 -ditelluro-2,2 0 -dithiophenecarboxylic acid, DTDTCA) that catalytically decomposes endogenous S-nitrosothiols (RSNOs) to nitric oxide (NO) in the presence of free thiols (RSHs) is used to prepare new types of NO generating polymers (NOGPs). In this work, DTDTCA is covalently linked to poly(allylamine hy...

A new amperometric sensor capable of responding to various biological S-nitrosothiol species (RSNOs) is described. The sensor is prepared using an organoditelluride-tethered poly(allyamine hydrochloride) (PAH) polymer crosslinked within a dialysis membrane support mounted at the distal surface of an amperometric NO probe. The surface immobilized or...

No Abstract Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/50672/1/2745_ftp.pdf

An organoditelluride (5,59-ditelluro-2,29-dithiophenecarboxylic acid) and a polymeric derivative thereof are shown to exhibit catalytic decomposition of S-nitrosothiols such as S-nitro-soglutathione (GSNO) and S-nitrosocysteine (CySNO). Physiological S-nitrosothiols (RSNOs) such as S-nitrosogluta-thione (GSNO), S-nitrosocysteine (CySNO), and S-nitr...

Described is a scalable synthetic route towards LB30057 (1) which is based upon a chiron approach using methyl tyrosinate hydrochloride as a starting material. In situ protection of methyl tyrosinate to its N,O-bis-trimethylsilyl derivative and subsequent N-selective introduction of naphthalenesulfonyl group provided methyl N-2-naphthalenesulfonylt...

(Figure Presented) In the matrix: A new cross-linked hydrogel polymer, poly(2-hydroxyethyl methacrylate) (pHEMA), containing appended Cu II-cyclen sites (cyclen = 1,4,7,10-tetraazacyclododecane) was prepared and shown to generate nitric oxide from endogenous S-nitrosothiol species (RSNO) typically found in circulating whole blood.

An efficient synthesis of the HIV-1 protease inhibitor LB71350 (1) is described. High diastereoselective epoxidation of the cis-allylic carbamate fragment of (5S)-[N-(benzyloxycarbonyl)-amino]-N-[2-methyl-(1R)-[(phenyl)carbonyl]-propyl]-6-phenylhex-(Z)-enamide (16) and one-pot preparation of N-[(1-methyl-ethoxy)carbonyl]-3-(methylsulfonyl)-L-valine...

LB30057 (1) is a selective and efficacious oral thrombin inhibitor. Fluorine-substitution on the phenylene ring of the benzamidrazone portion in both compound 1 and its derivatives gave, in many cases, enhanced oral absorption in rats while maintaining the intrinsic potency and selectivity. Compound 2 demonstrated a 3-fold increase in absorption.

A series of novel arylsulfonylpropargylglycinamide derivatives was investigated as thrombin inhibitors in which the SAR was focused on substituents at the acetylenic terminus. Several compounds in this series were identified as potent thrombin inhibitors (Ki up to 5 nM) that are highly selective over trypsin and other serine proteases as well.

Novel thrombin inhibitors incorporating thienylamidine at the P1 position were designed and synthesized. These compounds are potent, trypsin-selective and efficacious in the rat model of venous thrombosis. The proposed P1 binding mode in the thrombin active site was confirmed by X-ray crystallographic analysis.

An amidrazonophenylalanine derivative LB30057 (2) was identified as a potent (Ki = 0.38 nM), selective, and orally active thrombin inhibitor. As a continuation of studies into benzamidrazone-based thrombin inhibitors, we have structurally modified compound 2 by replacing the naphthyl group with a variety of hydrophobic moieties. This study led to d...

Systematic variation of the so-called P-pocket moiety of benzamidrazone-based selective thrombin inhibitors led to the discovery of LB30057. It is potent (Ki = 0.38 nM for human thrombin), selective (Ki = 3290 nM for bovine trypsin), and orally bioavailable (58% oral bioavailability in dogs). LB30057 was efficacious in thrombosis animal models.

Thrombin inhibitors with fimctionalized benzamidines as surrogates for arginine were designed, synthesized, and characterized. Amino acid sequence difference in the position 190 between thrombin and trypsin was exploited in the design to enhance selectivity over trypsin. A representative compound 6 showed high potency (Ki of 45.5 nM) and extremely...