Mi-Kyong Yoo

Targeted delivery of chitosan nanoparticles to Peyer’s patch using M cell-homing peptide selected by phage display technique

This study is aimed to develop an efficient oral vaccine carrier which specifically targets the follicle-associated epithelium region of Peyers patch (PP). M cell-homing peptide was selected by the phase display technique and its targeting efficiency was validated using chitosan nanoparticles (CNs) conjugated with the discovered peptide. A phage clone encoding CKSTHPLSC (CKS9) peptide sequence was selected by analysis of comparative superiority in transcytosis efficacy across the M cell layer in vitro and in vivo among the candidates. CKS9 was chemically conjugated to water-soluble chitosan (WSC) and the CKS9-immobilized chitosan nanoparticles (CKS9-CNs) were prepared by ionic gelation of CKS9-WSC with tripolyphosphate, yielding spherical nanoparticles around 226.2 +/- 41.9 nm. The targeting ability of CKS9-CNs to the M cell and to the PP regions of rat small intestine was investigated by in vitro transcytosis assay and closed ileal loop assay, respectively, and was visualized by fluorescence-microscopy analysis. CKS9-CNs were transported more effectively across the M cell model and accumulated more specifically into PP regions in comparison with CNs, indicating that CKS9 peptide prominently enhanced the targeting and transcytosis ability of CNs to PP regions. These results suggest that the CKS9-CNs could be used as a new carrier for oral vaccine delivery.

Folate-PEG-superparamagnetic iron oxide nanoparticles for lung cancer imaging

While superparamagnetic iron oxide nanoparticles (SPIONs) have been widely used in biomedical applications, rapid blood clearance, instability and active targeting of the SPIONs limit their availability for clinical trials. This work was aimed at developing stable and lung cancer targeted SPIONs. For this purpose firstly folic acid (FA)-conjugated poly(ethylene glycol) (FA-PEG) was synthesized, and FA-PEG-SPIONs were subsequently prepared by the reaction of FA-PEG with aminosilane-immobilized SPIONs. FA-PEG-SPIONs were labeled with Cy5.5 for optical imaging. The intracellular uptake of FA-PEG-SPIONs-Cy5.5 was evaluated in KB cells and lung cancer model mice to confirm active targeting. The sizes of the FA-PEG-SPIONs were little changed after up to 8 weeks at 4 °C, suggestive of very stable particle sizes. The results of fluorescent flow cytometry and confocal laser scanning microscopy suggest that the intracellular uptake of FA-PEG-SPIONs-Cy5.5 was greatly inhibited by pre-treatment with free folic acid, indicative of receptor-mediated endocytosis. Stronger optical imaging was observed in the lung cancer model mice for FA-PEG-SPIONs-Cy5.5 than PEG-SPIONs-Cy5.5 6 and 24 h post-injection through the tail vein, due to receptor-mediated endocytosis.

Biodegradable poly(ester amine) based on glycerol dimethacrylate and polyethylenimine as a gene carrier

Polyethylenimine (PEI) vectors are widely used in gene delivery because of their high transfection efficiency owing to a unique proton sponge effect. An increase in molecular weight increases transfection efficiency, but simultaneously results in increased toxicity. Therefore, the design and synthesis of new degradable gene delivery carriers having high transfection efficiencies and reduced cytotoxicity are necessary.

pH-sensitive and mucoadhesive thiolated Eudragit-coated chitosan microspheres

The aim of this study was using Eudragit-cysteine conjugate to coat on chitosan microspheres (CMs) for developing an oral protein drug delivery system, having mucoadhesive and pH-sensitive property. Bovine serum albumin (BSA) as a protein model drug was loaded in thiolated Eudragit-coated CMs (TECMs) to study the release character of the delivery system. After thiolated Eudragit coating, it was found that the release rate of BSA from BSA-loaded TECMs was observably suppressed at pH 2.0 PBS solution, while at pH 7.4 PBS solution the BSA can be sustainingly released for several hours. The structural integrity of BSA released from BSA-loaded TECMs was guaranteed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and circular dichroism (CD) spectroscopy. The mucoadhesive property of TECMs was evaluated and compared with CMs and Eudragit-coated chitosan microspheres (ECMs). It was confirmed that after coating thiolated Eudragit, the percentage of TECMs remained on the isolated porcine intestinal mucosa surface was significantly higher than those of CMs and ECMs. Likewise, gamma camera imaging of Tc-99m labeled microsphere distribution in rats after oral administration also suggested that TECMs had comparatively stronger mucoadhesive characters. Therefore, our results indicated that TECMs have potentials to be an oral protein drug carrier.

Targeted delivery of mannan-coated superparamagnetic iron oxide nanoparticles to antigen-presenting cells for magnetic resonance-based diagnosis of metastatic lymph nodes in vivo

Metastatic lymph nodes (LN) originate from primary cancer cells that metastasize to the lymphatic system. It is difficult to non-invasively discriminate between metastatic LN and normal LN because of their similarities in size and shape. Magnetic resonance (MR) contrast agents are widely utilized to enhance the image contrast among different tissues. Currently available dextran-based contrast agents are non-specifically internalized by macrophages. Therefore, the aim of this study was to develop mannan-coated superparamagnetic iron oxide nanoparticles (mannan-SPION) for specific delivery to immune cells in LN by receptor-mediated endocytosis for facilitated uptake in the target cells and faster acquisition of MR images. Mannan is a water soluble polysaccharide with a high content of D-mannose residues that can be recognized by mannose receptors on activated macrophages and dendritic cells. Mannan-SPION are proven to be suitable for MRI due to their small size, excellent aqueous stability, and lower cytotoxicity. Mannan-SPION are taken up by antigen-presenting cells such as macrophages and dendritic cells, which could be confirmed by Prussian blue and fluorescent staining. In addition, mannan-SPION exhibit enhanced delivery efficiency in targeting macrophages in LN in vivo compared with polyvinyl alcohol (PVA)-SPION. More specifically, the enhancement of MRI of LN by mannan-SPION increased dramatically during the earlier stages after intravenous injection, compared with PVA-SPION as a control, which indicates the potential for successful and early detection of metastastatic LN.

Release of Ciprofloxacin from Chondroitin 6-Sulfate-Graft-Poloxamer Hydrogel In Vitro for Ophthalmic Drug Delivery

The system was designed to use Poloxamer as a vehicle for ophthalmic drug delivery using in situ gel formation property. To enhance the wound healing and cell adhesion as well as transparency of Poloxamer hydrogel, chondroitin 6-sulfate (C6S) was introduced into Poloxamer. For this purpose, mono amine-terminated Poloxamer (MATP), which was end-capped with ethylene amine group only in one side of terminal hydroxyl groups of Poloxamer, was synthesized. Subsequently, C6S-graft-Poloxamer copolymer (C6S-g-Poloxamer) was prepared by reaction between the amine groups of MATP and carboxyl groups of C6S in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carboimide (EDC). The coupling of MATP with C6S was clarified by 1H-NMR and FT-IR spectroscopy. The gelation temperature of graft copolymers was determined by measuring the temperature at which immobility of the meniscus in each solution was first noted. Release behavior of ciprofloxacin from C6S-g-Poloxamer hydrogel in vitro was investigated as a function of C6S content in the graft copolymer by a spectrophotometric assay at 287 nm using an UV spectrophotometer. Differences in the adhesion and morphology of human lens cell between Poloxamer- and C6S-g-Poloxamer-coated surfaces were also investigated. The gelation temperatures of C6S-g-Poloxamer copolymers were lowered with increasing of the concentration of the copolymer and decreasing of C6S content. The release of ciprofloxacin from the graft copolymer was sustained compared with Poloxamer itself and decreased with increasing the content of C6S in the copolymer due to the in situ gel formation of the copolymer and viscous properties of C6S. Human lens cells (B3) adhered to C6S-g-Poloxamer-coated surface were observed as transformed shapes after 2 days. The bioadhesive and thermally gelling of these graft copolymers will be expected to be an excellent drug carrier for the prolonged delivery to surface of the eye.

Immune cells-specific delivery of mannan-coated superparamagnetic iron oxide nanoparticles for the detection of metastatic lymph node

Detection of lymph node (LN) metastasis by magnetic resonance imaging (MRI) has obtained clinical significance for treating cancer patients. LN metastasis often happens through regional lymphatic system, leading to distal tumor formation including lungs, liver and bones. Successful imaging of small and microscopic LN metastasis provides the helpful information in deciding the therapeutic option of cancer. Mannan is a water-soluble polysaccharide having high content of D-mannose residues which can be recognized by mannose receptors on activated macrophages and dendritic cells. Mannan-coated superparamagnetic iron oxide nanoparticles (Mannan-SPION) were developed to be specifically delivered to immune cells in lymph node by receptor-mediated endocytosis. Mannan-SPION was proven to be suitable for MR imaging due to small size, excellent stability in ferrofluid, and low cytotoxicity. From the Prussian blue staining, Mannan-SPION was showed their ability to be taken up by immune cells such as macrophage and dendritic cell. In addition mannan-SPION exhibited enhanced targeted delivery efficiency to macrophages in lymph nodes in vivo compared with PVA-SPION. Especially, LN enhancement of Mannan-SPION on MRI was dramatically increased at the later stage after intravenous injection compared with PVA-SPION control, indicative of the potential to successfully detect micrometastasis in LN.