Jung Bok Lee

Gold nanoparticles surface-functionalized with paclitaxel drug and biotin receptor as theranostic agents for cancer therapy.

We describe in this study whether the gold nanoparticle (AuNP) surface-functionalized with PEG, biotin, paclitaxel (PTX) and rhodamine B linked beta-cyclodextrin (β-CD) (AuNP-5) can be useful as a theranostic agent for cancer therapy without the cytotoxic effect on normal cells. Prior to surface-functionalizing AuNPs, the cytotoxicity of the nanoparticles was evaluated, followed by their cytocompatibility. PTX, an anti-cancer agent, formed inclusion complexations with β-CD conjugated AuNPs, and effectively released from the AuNP-2 surface-functionalized with PEG, beta-cyclodextrin (β-CD) and paclitaxel (PTX) using the intracellular glutathione (GSH) level (10 mm). Two types of AuNP-4 surface-functionalized with PEG and rhodamine B linked β-CD and AuNP-5 surface-functionalized PEG, biotin and rhodamine B linked β-CD were used for evaluating their specific interaction on cancer cells such as HeLa, A549 and MG63. These were also tested against normal NIH3T3 cell, determining that the AuNP-5 was more effectively involved with the cancer cells. Confocal laser scanning microscopy (CLSM), fluorescence-activated cell-sorting (FACS) and cell viability analyses showed that the AuNP-5 plays a significant role in the diagnosis and therapy of the cancer cells, and may be used in theranostic agents.

Electrospun gelatin/polyurethane blended nanofibers for wound healing

In this study, we prepared a blended nanofiber scaffold using synthetic and natural polymers, polyurethane (PU) and gelatin respectively, using the electrospinning method to prepare a material for wound dressing. In order to confirm the properties of this gelatin/PU blended nanofiber scaffold, we performed scanning electron microscopy, atomic force microscopy, attenuated total reflectance Fourier-transform infrared spectroscopy, thermal gravimetric analysis, contact angle, water uptake, mechanical property, recovery, and degradation tests, and cellular response. The results obtained indicate that the mean diameter of these nanofibers was uniformly electrospun and ranged from 0.4 to 2.1 microm. According to the results, when the amount of gelatin in the blended solution decreased, the contact angle increased and water uptake of the scaffold decreased concurrently. In the mechanical tests, the blended nanofibrous scaffolds were elastic, and elasticity increased as the total amount of PU increased. Moreover, as the total amount of gelatin increased, the cell proliferation increased with the same amount of culture time. Therefore, this gelatin/PU blended nanofiber scaffold has potential application for use as a wound dressing.

Photo-cured hyaluronic acid-based hydrogels containing simvastatin as a bone tissue regeneration scaffold

We describe in this study the positive influences on in vitro and in vivo osteogenesis of photo-cured hyaluronic acid (HA) hydrogels loaded with simvastatin (SIM). Prior to loading SIM, we first characterized the HA hydrogels for their mechanical properties and swelling ratios. The results from this testing indicated that these two factors improved as the substitution degree of 2-aminoethyl methacrylate (AEMA) increased. MTT and live/dead assays showed that the HA hydrogels have good biocompatibility for use as scaffolds for bone tissue regeneration. Moreover, another MTT assay showed that the photo-cured HA hydrogels III fabricated with 30% AEMA (300 mg) conjugated HA (HA-AEMA iii) loaded with between 0.1 and 1 mg of SIM had a similar cytotoxicity as compared to the HA hydrogel III itself. The sustained release of SIM was observed to occur in the HA hydrogel III loaded with 1 mg of SIM. In vitro and in vivo experiments showed that the HA hydrogel III loaded with 1 mg of SIM had a significant influence on osteogenesis.

Electrospun chitosan nanofibers with controlled levels of silver nanoparticles. Preparation, characterization and antibacterial activity

The ideal wound dressing would have properties that allow for absorption of exudates, and inhibition of microorganism for wound protection. In this study, we utilized an electrospinning (ELSP) technique to design a novel wound dressing. Chitosan (CTS) nanofibers containing various ratios of silver nanoparticles (AgNPs) were obtained. AgNPs were generated directly in the CTS solution by using a chemical reduction method. The formation and presence of AgNPs in the CTS/AgNPs composite was confirmed by x-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV) and thermogravimetric analysis (TGA). The electrospun CTS/AgNPs nanofibers were characterized morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These nanofibers were subsequently tested to evaluate their antibacterial activity against gram-negative Pseudomonas aeruginosa (P. aeruginosa) and gram-positive Methicillin-resistant Staphylococcus aureus (MRSA). Results of this antibacterial testing suggest that CTS/AgNPs nanofibers may be effective in topical antibacterial treatment in wound care.

Enhanced bone regeneration with a gold nanoparticle–hydrogel complex

Gold nanoparticles (GNPs) are widely used in diagnostics, drug delivery, biomedical imaging, and photo-thermal therapy due to their surface plasmon resonance, fluorescence, and easy-surface functionalization. According to recent studies, GNPs display a positive effect on the osteogenic differentiation of mesenchymal stem cells (MSCs) and MC3T3-E1 osteoblast-like cells. The aim of this study was to develop a new approach for bone tissue regeneration based on the utilization of a biodegradable hydrogel loaded with GNPs. We have used photo-curable gelatin hydrogels (Gel) in order to provide a proof of principle of GNPs in regeneration strategies for bone tissue repair. We have investigated the effects of these Gel-GNP composite hydrogels both in vitro and in vivo. The in vitro results showed that the hydrogels loaded with GNPs promote proliferation, differentiation, and alkaline phosphate (ALP) activities of human adipose-derived stem cells (ADSCs) as they differentiate towards osteoblast cells in a dose-dependent manner. Moreover, the in vivo results showed that these hydrogels loaded with high concentrations of GNPs had a significant influence on new bone formation. Through these in vitro and vivo tests, we found that the Gel-GNP can be a useful material for bone tissue engineering.

Enhancement of ectopic bone formation by bone morphogenetic protein-2 delivery using heparin-conjugated PLGA nanoparticles with transplantation of bone marrow-derived mesenchymal stem cells.

This study was performed to determine if a combination of previously undifferentiated bone marrow-derived mesenchymal stem cells (BMMSCs) and exogenous bone morphogenetic protein-2 (BMP-2) delivered via heparin-conjugated PLGA nanoparticles (HCPNs) would extensively regenerate bone in vivo. In vitro testing found that the HCPNs were able to release BMP-2 over a 2-week period. Human BMMSCs cultured in medium containing BMP-2-loaded HCPNs for 2 weeks differentiated toward osteogenic cells expressing alkaline phosphatase (ALP), osteopontin (OPN) and osteocalcin (OCN) mRNA, while cells without BMP-2 expressed only ALP. In vivo testing found that undifferentiated BMMSCs with BMP-2-loaded HCPNs induce far more extensive bone formation than either implantation of BMP-2-loaded HCPNs or osteogenically differentiated BMMSCs. This study demonstrates the feasibility of extensive in vivo bone regeneration by transplantation of undifferentiated BMMSCs and BMP-2 delivery via HCPNs.

The effect of gold nanoparticle size on osteogenic differentiation of adipose-derived stem cells.

There have been many medical applications based on gold nanoparticles (GNPs) over the past several centuries. Recently, researchers have focused on bone tissue engineering applications utilizing GNPs. The effect of various sizes of gold nanoparticles on the differentiation of human adipose-derived stem cells (ADSCs) into osteoblasts was investigated. The concentration of gold nanoparticles was fixed at 1 μM and varying sizes of 15, 30, 50, 75 and 100 nm (spherical GNPs) were used. The lack of cytotoxicity was confirmed by establishing viability of ADSCs using cell counting kit-8 (CCK-8) and live/dead assays. The results showed that each size of GNPs had no significant toxicity on ADSCs during 1 week of incubation. Osteogenic differentiation of ADSCs was confirmed by alkaline phosphatase (ALP) staining, ALP activity, calcium deposition, and real time PCR experiments. It was found, through dark field assays and microscope cell images, that 30 nm and 50 nm GNPs were preferentially up taken into the ADSCs. As expected, all sizes of gold nanoparticles promoted the differentiation of ADSCs toward osteoblasts more than control. Among all sizes, 30 and 50 nm GNPs appeared to have the highest differentiation rates. The data consistently demonstrated that 30 and 50 nm GNPs are the most effective in promoting osteogenic differentiation of ADSCs.

Photo-cured hyaluronic acid-based hydrogels containing growth and differentiation factor 5 (GDF-5) for bone tissue regeneration

In this study we describe the generation and influences on in vitro and in vivo osteogenesis of photo-cured hyaluronic acid (HA) hydrogels loaded with growth and differentiation factor 5 (GDF-5). Prior to loading GDF-5, we characterized the release profiles from these hydrogels and tested their respective cell viability, differentiation and in vivo bone regeneration. The results from this testing indicated that GDF-5 was observed to release in a sustained manner from the HA hydrogels I-III. MTT and Live/Dead assays showed that the HA hydrogels I-III have good biocompatibility for use as scaffolds for bone tissue regeneration. In vitro cell tests showed a higher level of MC3T3-E1 cell proliferation and differentiation on HA hydrogels I-III than on HA hydrogel 0. Moreover, in vivo animal tests showed that the HA hydrogels I and III had a significant improvement on osteogenesis. Overall, our results suggest that the HA-based hydrogel is a good biomaterial to deliver osteogenic differentiation factors such as GDF-5, and GDF-5 can be useful as an effective alternative to aid new bone formation.

Inhibition of Osteoclast Differentiation by Gold Nanoparticles Functionalized with Cyclodextrin Curcumin Complexes

Gold nanoparticles (GNPs) have been previously reported to inhibit osteoclast (OC) formation. However, previous research only confirmed the osteoclastogenesis inhibitory effect under in vitro conditions. The aim of this study was to develop a therapeutic agent for osteoporosis based on the utilization of GNPs and confirm their effect both in vitro and in vivo. We prepared β-cyclodextrin (CD) conjugated GNPs (CGNPs), which can form inclusion complexes with curcumin (CUR-CGNPs), and used these to investigate their inhibitory effects on receptor activator of nuclear factor-κb ligand (RANKL)-induced osteoclastogenesis in bone marrow-derived macrophages (BMMs). The CUR-CGNPs significantly inhibited the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells in BMMs without inducing cytotoxicity. The mRNA expressions of genetic markers of OC differentiation including c-Fos, nuclear factor of activated T cells 1 (NFATc1), TRAP, and osteoclast associated receptor (OSCAR) were significantly decreased in the presence of CUR-CGNPs. In addition, the CUR-CGNPs inhibited OC differentiation of BMMs through suppression of the RANKL-induced signaling pathway. Additionally, CUR-CGNPs caused a decrease in RANKL-induced actin ring formation, which is an essential morphological characteristic of OC formation allowing them to carry out bone resorption activity. Furthermore, the in vivo results of an ovariectomy (OVX)-induced osteoporosis model showed that CUR-CGNPs significantly improved bone density and prevented bone loss. Therefore, CUR-CGNPs may prove to be useful as therapeutic agents for preventing and treating osteoporosis.

ZrO2 surface chemically coated with hyaluronic acid hydrogel loading GDF-5 for osteogenesis in dentistry

The objective of this study was to modify zirconium dioxide (ZrO(2)) with photo-cured hyaluronic acid hydrogel (pcHAgel), and to subsequently evaluate the bone regeneration potential of the modified ZrO(2). In the present study, HA grafted onto a ZrO(2) substrate was investigated for its biocompatibility and other properties. We describe the positive influences of ZrO(2) surface-modified with pcHAgel (Zr-3) containing two different loads of growth and differentiation factor-5 (GDF-5) to aid new bone formation as compared to the same amount of BMP-2 (Zr-4-7). We characterized the Zr-3 for their surface morphology and chemical properties. Atomic force microscopy (AFM), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) showed that the pcHAgel was successfully grafted onto the ZrO(2) surface. The sustained release of GDF-5 and BMP-2 were observed to occur in the Zr-4-7. In vitro cell tests showed a higher level of MG63 cell proliferation and differentiation on Zr-4-7 than on Zr-3. The Zr-3 is a good biomaterial to deliver osteogenic differentiation factors such as BMP-2 and GDF-5, and GDF-5 can be useful as an effective alternative to aid new bone formation as compared to BMP-2.