Jeon Soo Shin

Noninvasive Remote-Controlled Release of Drug Molecules in Vitro Using Magnetic Actuation of Mechanized Nanoparticles

Mesoporous silica nanoparticles are useful nanomaterials that have demonstrated the ability to contain and release cargos with mediation by gatekeepers. Magnetic nanocrystals have the ability to exhibit hyperthermic effects when placed in an oscillating magnetic field. In a system combining these two materials and a thermally sensitive gatekeeper, a unique drug delivery system can be produced. A novel material that incorporates zinc-doped iron oxide nanocrystals within a mesoporous silica framework that has been surface-modified with pseudorotaxanes is described. Upon application of an AC magnetic field, the nanocrystals generate local internal heating, causing the molecular machines to disassemble and allowing the cargos (drugs) to be released. When breast cancer cells (MDA-MB-231) were treated with doxorubicin-loaded particles and exposed to an AC field, cell death occurred. This material promises to be a noninvasive, externally controlled drug delivery system with cancer-killing properties.

Nanoscale Magnetism Control via Surface and Exchange Anisotropy for Optimized Ferrimagnetic Hysteresis

With the aim of controlling nanoscale magnetism, we demonstrate an approach encompassing concepts of surface and exchange anisotropy while reflecting size, shape, and structural hybridization of nanoparticles. We visualize that cube has higher magnetization value than sphere with highest coercivity at 60 nm. Its hybridization into core-shell (CS) structure brings about a 14-fold increase in the coercivity with an exceptional energy conversion of magnetic field into thermal energy of 10600 W/g, the largest reported to date. Such capability of the CS-cube is highly effective for drug resistant cancer cell treatment.

A magnetic switch for the control of cell death signalling in in vitro and in vivo systems

The regulation of cellular activities in a controlled manner is one of the most challenging issues in fields ranging from cell biology to biomedicine. Nanoparticles have the potential of becoming useful tools for controlling cell signalling pathways in a space and time selective fashion. Here, we have developed magnetic nanoparticles that turn on apoptosis cell signalling by using a magnetic field in a remote and non-invasive manner. The magnetic switch consists of zinc-doped iron oxide magnetic nanoparticles (Zn(0.4)Fe(2.6)O(4)), conjugated with a targeting antibody for death receptor 4 (DR4) of DLD-1 colon cancer cells. The magnetic switch, in its On mode when a magnetic field is applied to aggregate magnetic nanoparticle-bound DR4s, promotes apoptosis signalling pathways. We have also demonstrated that the magnetic switch is operable at the micrometre scale and that it can be applied in an in vivo system where apoptotic morphological changes of zebrafish are successfully induced.

Artificial Control of Cell Signaling and Growth by Magnetic Nanoparticles

Mechanical stresses on biological objects can lead to changes in a wide range of cellular properties, such as cell shape, cytoskeletal organization, and cell fate, by means of physical stimulations using dielectricity, optical trapping, and magnetic cytometry. In particular, micrometer-sized magnetic beads have been useful since their first utilization by Crick and Hughes to draw mechanical stresses on biological objects by developing techniques such as magnetic twisting, pulling, and cell-stretching cytometry. With the use of such magnetic stimulations, the roles of mechanical stresses for cell characteristics have been studied, which include cytoplasmic viscosity, cytoskeletal mechanotransduction, and mechanical calcium responses. Further scientific breakthroughs in this research field have depended on molecular-level understanding of mechanobiological processes and the induction of changes in cellular functions and/or cytoskeletal structures. The goal is to bring about single-cell or subcellular-level imaging and actuation of biological objects with high target specificity. Nanoscale probes and actuators are important because of their small sizes, which are comparable to those of many biologically meaningful molecules such as DNAs and proteins. In addition, their ability to attach multivalence functional groups would be another advantage. By employing nanoparticles, difficult challenges associated with currently used micrometer-scale magnetic particles, such as probing and manipulation of a single receptor without disturbing any other rheological or cytoskeletal properties of the entire cell, can be overcome. Recently, the groups of Ingber and Dobson have independently demonstrated that activation of ion channels is possible by using nanoscale magnetic particles. These efforts have demonstrated that FceRI, a cellular membrane receptor, can be magnetically agglomerated to activate the Ca signal. On the other hand, TREK-1, a membrane protein for the K ion channel, is specifically activated by magnetic nanoparticles with size as small as 130 nm. While these two pioneering works focused on ion-channel activations, new conceptual advances and other applications of nanoscale magneto-activated cellular signaling (N-MACS) are widely open to exploration. Herein, we demonstrate for the first time that receptormediated artificial triggering of cell growth in the preangiogenesis stage is possible by the N-MACS approach. Angiogenesis is a vital process both for the growth and development of blood vessels and for tumor metastasis. Conventionally, this process is initiated by several interactions that take place between specific receptors and ligands on the cell surface. The Tie2/angiopoietin(Ang) pair, in which one Ang molecule binds to clusterize three to five Tie2 receptors, is regarded as one of the important receptor–ligand interactions. This cluster formation is critical to activate multiple signaling steps and eventually participates in the angiogenic processes. Instead of using such ligands, in our study a TiMo214 monoclonal antibody(mAb)-conjugated Zn-doped ferrite magnetic nanoparticle (Ab-Zn-MNP) is employed to target and magnetically manipulate Tie2 receptors through the steps in Figure 1a–c. To achieve this result, two permanent NdFeB magnets are positioned to exert an external magnetic field of about 0.15 T, with horizontal magnetic field lines that are oriented in the manner shown in Figure 1d. At this magnetic field strength, magnetization of Ab-Zn-MNPs can be saturated in plane (Figure 1e), which induces strong attractive forces between the dipoles of neighboring nanoparticles. This phenomenon results in the aggregation of Ab-Zn-MNPs. For successful magnetic manipulation under mild external magnetic field conditions, we utilized a high-performance 15 nm Zn-doped ferrite magnetic nanoparticle (Zn-MNP) instead of a conventional magnetic nanoparticle, since it exhibits a very high saturation magnetization (Figure 1e,f) [*] J.-H. Lee, M. H. Cho, Prof. J. Cheon Department of Chemistry, Yonsei University Seoul 120-749 (Korea) Fax: (+ 82)2-364-7050 E-mail: jcheon@yonsei.ac.kr E. S. Kim, M. Son, S.-I. Yeon, Prof. J.-S. Shin Department of Microbiology Institute for Immunology and Immunological Diseases College of Medicine, Yonsei University Seoul 120-752 (Korea) Fax: (+ 82)2-392-7088 E-mail: jsshin6203@yuhs.ac [] These authors contributed equally to this work.

NOD-Like Receptors in Infection, Immunity, and Diseases

Nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) are pattern-recognition receptors similar to toll-like receptors (TLRs). While TLRs are transmembrane receptors, NLRs are cytoplasmic receptors that play a crucial role in the innate immune response by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Based on their N-terminal domain, NLRs are divided into four subfamilies: NLRA, NLRB, NLRC, and NLRP. NLRs can also be divided into four broad functional categories: inflammasome assembly, signaling transduction, transcription activation, and autophagy. In addition to recognizing PAMPs and DAMPs, NLRs act as a key regulator of apoptosis and early development. Therefore, there are significant associations between NLRs and various diseases related to infection and immunity. NLR studies have recently begun to unveil the roles of NLRs in diseases such as gout, cryopyrin-associated periodic fever syndromes, and Crohns disease. As these new associations between NRLs and diseases may improve our understanding of disease pathogenesis and lead to new approaches for the prevention and treatment of such diseases, NLRs are becoming increasingly relevant to clinicians. In this review, we provide a concise overview of NLRs and their role in infection, immunity, and disease, particularly from clinical perspectives.

Identification of lipopolysaccharide-binding peptide regions within HMGB1 and their effects on subclinical endotoxemia in a mouse model.

Lipopolysaccharide (LPS) triggers deleterious systemic inflammatory responses when released into the circulation. LPS‐binding protein (LBP) in the serum plays an important role in modifying LPS toxicity by facilitating its interaction with LPS signaling receptors, which are expressed on the surface of LPS‐responsive cells. We have previously demonstrated that high mobility group box 1 (HMGB1) can bind to and transfer LPS, consequently increasing LPS‐induced TNF‐α production in human peripheral blood mononuclear cells (PBMCs). We report here on the identification of two LPS‐binding domains within HMGB1. Furthermore, using 12 synthetic HMGB1 peptides, we define the LPS‐binding regions within each domain. Among them, synthetic peptides HPep1 and HPep6, which are located in the A and B box domains of HMGB1, bind to the polysaccharide and lipid A moieties of LPS respectively. Both HPep1 and HPep6 peptides inhibited binding of LPS to LBP and HMGB1, LBP‐mediated LPS transfer to CD14, and cellular uptake of LPS in RAW264.7 cells. These peptides also inhibited LPS‐induced TNF‐α release in human PBMCs and induced lower levels of TNF‐α in the serum in a subclinical endotoxemia mouse model. These results indicate that HMGB1 has two LPS‐binding peptide regions that can be utilized to design anti‐sepsis or LPS‐neutralizing therapeutics.

Drug-loaded gold plasmonic nanoparticles for treatment of multidrug resistance in cancer.

To investigate the possibility of treating multidrug-resistant tumors with targeted chemo-photothermal treatment, we conducted in vitro and in vivo studies using a doxorubicin (DOX)-resistant DLD-1 cell line (DLD-1/DOX) and nude mice with human xenograft tumors, respectively. The chemo-photothermal treatment consisted of DOX-loaded-poly(lactic-co-glycolic acid)-Au half-shell nanoparticles with targeting moieties of anti-death receptor-4 monoclonal antibody conjugated to the Au surface. The cells or xenografted tumors treated with nanoparticles were exposed to near infrared light for 10 min, which caused an increase in temperature to 45 °C. Chemo-photothermal treatment resulted in a large reduction in the rate of tumor xenograft growth on DLD-1/DOX tumor-bearing mice with a much smaller dose of DOX than conventional DOX chemotherapy. These results demonstrate that targeted chemo-photothermal treatment can provide high therapeutic efficacy and low toxicity in the treatment of multidrug-resistant tumors.

Real-time monitoring of 3D cell culture using a 3D capacitance biosensor

Three-dimensional (3D) cell cultures have recently received attention because they represent a more physiologically relevant environment compared to conventional two-dimensional (2D) cell cultures. However, 2D-based imaging techniques or cell sensors are insufficient for real-time monitoring of cellular behavior in 3D cell culture. Here, we report investigations conducted with a 3D capacitance cell sensor consisting of vertically aligned pairs of electrodes. When GFP-expressing human breast cancer cells (GFP-MCF-7) encapsulated in alginate hydrogel were cultured in a 3D cell culture system, cellular activities, such as cell proliferation and apoptosis at different heights, could be monitored non-invasively and in real-time by measuring the change in capacitance with the 3D capacitance sensor. Moreover, we were able to monitor cell migration of human mesenchymal stem cells (hMSCs) with our 3D capacitance sensor.

Capacitance-based assay for real-time monitoring of endocytosis and cell viability

Label-free cell-based assays have emerged as a promising means for high-throughput screening. Most label-free sensors are based on impedance measurements that reflect the passive electrical properties of cells. Here we introduce a capacitance-based assay that measures the dielectric constant (capacitance) of biological cells, and demonstrate the feasibility of analyzing endocytosis and screening chemotherapeutic agents with this assay. Endocytosis induces a change in the zeta potential, leading to a change in the dielectric constant which enables real-time endocytosis monitoring using the capacitance sensor. Additionally, since the dielectric constant is proportional to cell radius and cell volume, cell viability can be estimated from the change in capacitance. Therefore, the capacitance sensor array can also be used for cytotoxicity testing for large-scale chemotherapeutic screening.

Programmed death-1 (PD-1) gene polymorphisms lodged in the genetic predispositions of Kawasaki Disease

The purpose of this study is to investigate the association of programmed death-1 gene (PD-1) polymorphisms with genetic predispositions to Kawasaki disease (KD). A total of 73 patients with KD and 100 healthy controls were enrolled from 2007 to 2008. Two single nucleotide polymorphisms of the PD-1 gene, rs41386349 and rs2227981, were analyzed. Higher T allele frequency of rs41386349 was found in the patient group than the control group (pu2009=u20090.007, odds ratio (OR)u2009=u20091.9, 95% CIu2009=u20091.2–2.9). PD-1 rs2227981 polymorphism was not significant in patients with KD comparing with the control group (pu2009=u20090.4, ORu2009=u20091.2 (0.8–1.9)). Furthermore, no difference of PD-1 polymorphisms between patients with coronary artery dilatation (CAD) and those without CAD was found. Our data support the possibility that PD-1 gene polymorphism may be related with the genetic susceptibility of KD in Korean population.