Wan-Kyu Oh

Cellular Uptake, Cytotoxicity, and Innate Immune Response of Silica−Titania Hollow Nanoparticles Based on Size and Surface Functionality

Silica-titania hollow nanoparticles (HNPs) with uniform diameters of 25, 50, 75, 100, and 125 nm were fabricated by dissolution and redeposition method in order to evaluate size dependent cellular response. Surface-modified HNPs with cationic, anionic, and neutral functional group were prepared by silane treatment. We systematically investigated cellular internalization, toxicity, and innate immune response of HNPs in human breast cancer (SK-BR-3) and mouse alveolar macrophage (J774A.1) cells. Size- and surface functionality-dependent cellular uptake of HNPs was investigated by fluorescence labeling (fluorescein isothiocyanate), inductively coupled plasma-emission spectroscopy, and ultrastructural resolution using transmission electron microscopy. Viability, reactive oxygen species, and apoptosis/necrosis of HNP-treated J774A.1 revealed the size-dependent phenomenon. Innate immune response of HNP-treated macrophages was measured by three cytokines such as interleukin-1, interleukin-6, and tumor necrosis factor α. Among the HNPs of different sizes, 50-nm HNPs demonstrated the highest toxic influence on macrophages. Among the HNPs with surface functionalities, cationic HNPs demonstrated the most toxic effect on J774A.1 and the highest uptake efficiency. The toxicity results of HNP-treated macrophages were consistent with the cellular internalization efficiency. These findings provide size- and surface functionality-dependent nanotoxicity and uptake of HNPs, and lead to HNPs for bioapplications such as drug delivery and imaging probe.

Size control of magnetic carbon nanoparticles for drug delivery

Carbonized polypyrrole nanoparticles with controlled diameters were readily fabricated by the pyrolysis of polypyrrole nanoparticles. The carbonized polypyrrole nanoparticles showed narrow size distribution, large micropore volume, and high surface area. Magnetic phases were introduced into the carbon nanoparticles during the pyrolysis without sophisticated process, which resulted in useful magnetic properties for selective nanoparticle separation. Field emission scanning electron microscopy, Raman spectrometer, N(2) adsorption/desorption, X-ray diffraction, and superconducting interference device were employed for characterizing the carbonized polypyrrole nanoparticles. Hydrophobic guest molecules were incorporated into the carbonized polypyrrole nanoparticles by surface adsorption, pore filling, and surface covalent coupling. The carbonized polypyrrole nanoparticles exhibited embedding capability using pyrene as a typical hydrophobic fluorescent molecule. In addition, ibuprofen was incorporated into the carbon nanoparticles, and drug-loaded carbon nanoparticles sustained release property. In addition, the carbonized polypyrrole nanoparticles revealed low toxicity at concentrations below 100 microg mL(-1) via cell viability test and were uptaken inside the cells. These results suggest a new platform for the drug delivery using carbonized polypyrrole nanoparticles.

Shape-dependent cytotoxicity and proinflammatory response of poly(3,4-ethylenedioxythiophene) nanomaterials.

Poly(3,4-ethylenedioxythiophene) (PEDT) is recognized as one of the most promising conducting polymers for future applications in the fields of electronics, optics, energy storage/conversion, and biomedical science. The toxicity of PEDT could be considered to affect the potential for its widespread application. Herein, the cytotoxicity and proinflammatory response of PEDT nanomaterials of three different shapes toward human lung fibroblast (IMR90) and mouse alveolar macrophage (J774A.1) cells are investigated. The shape-dependent toxicity of the PEDT nanomaterials is evaluated by examining cell morphological change, cytotoxicity, apoptosis/necrosis, oxidative stress, and immune response. The cytotoxicity and apoptosis of the nanomaterials increase with their decreasing aspect ratio in both cell lines. The formation of reactive oxygen species in cells treated with PEDT nanomaterials is dependent on the shape and concentration of the nanomaterial. Proinflammatory cytokines, such as interleukin-1, interleukin-6, and tumor necrosis factor alpha from macrophages, are induced by PEDT nanomaterial-treated cells.

Conducting Polymer Nanomaterials for Biomedical Applications: Cellular Interfacing and Biosensing

Recently, conducting polymer (CP) nanomaterials have shown outstanding chemical and physical properties compared with ceramic and metal nanomaterials. Thus, significant efforts have been made to fabricate CPs that enable various biomedical applications, such as high-performance biosensing and cellular interfacing. Although sensing or measuring devices based on CP nanomaterials have shown excellent electrical and physical properties, their limitations, such as the minimum detectable level (MDL), cytotoxicity assessments, and reliable synthesis methods, remain challenges to realizing high-performance biomedical geometries. In this article, we provide the general information on CP nanomaterials and their biomedical applications focusing especially on cellular interfacing and biosensing. Moreover, we discuss perspectives for state-of-the-art biomedical geometries using various CP nanomaterials.

Fluorescent Polymer Nanoparticle for Selective Sensing of Intracellular Hydrogen Peroxide

Fluorescent boronate-modified polyacrylonitrile (BPAN) nanoparticles of 50 nm diameter were fabricated for use as a selective H(2)O(2) sensor. The fluorescence intensity changed and an emission peak shifted when BPAN nanoparticles selectively interacted with H(2)O(2), relative to other reactive oxygen species (ROS). The BPAN nanoparticles undergo photoinduced electron transfer (PET) between a Schiff base moiety and boronate, which enhances the fluorescence and makes the nanoparticles suitable for selective ROS recognition. We demonstrate the use of these nanoparticles as a detector of endogenous H(2)O(2) produced in living cells. The representative features of the fluorescent BPAN nanoparticles that make them particularly attractive for H(2)O(2) and ROS detection are the following: they are easily synthesized as PET sensors; they exhibit a characteristic emission peak and peak shift that distinguishes reaction with H(2)O(2) from other ROS; and compared to organic compounds, the sensing moiety on BPAN polymer nanoparticles is more thermally stable and has superior mechanical properties, enabling their use in various biomedical applications.

Cellular uptake, cytotoxicity, and ROS generation with silica/conducting polymer core/shell nanospheres

The cellular response to conducting polymer (CP) nanospheres with similar physical properties was evaluated by in vitro cellular uptake and cytotoxicity in mouse macrophage RAW 264.7 and rat pheochromocytoma PC-12 cells. Four different CPs (polythiophene, poly(3,4-ethylenedioxythiophene), polyaniline, and polypyrrole) were deposited onto silica nanoparticles with a diameter of ca. 22 nm. Cellular uptake of silica/CP core/shell nanospheres in both cell lines was observed by transmission electron microscopy and they were internalized via phagocytosis and endocytosis. Cytotoxic effects were systemically assessed using live-cell microscopy, viability, oxidative stress, and lactate dehydrogenase assays. Silica/polythiophene core/shell nanospheres were the most toxic in both cell lines examined, because of the cellular effects of sulfur atoms. On the other hand, silica/polypyrrole core/shell nanospheres caused the lowest levels of toxicity in both cell lines. Furthermore, both rat and mouse cell viability was concentration-dependent with the nanospheres. These findings enhance nanotoxicological information regarding CP nanospheres when used with macrophage and neuronal cells, which may be useful in their application in bioelectronic and biomedical fields.

Fluorescent europium-modified polymer nanoparticles for rapid and sensitive anthrax sensors.

Novel fluorescent polyacrylonitrile nanoparticles were synthesized by microemulsion polymerization and Schiff base modification. By further modification with europium, the polyacrylonitrile nanoparticles could be used as a highly sensitive and rapid sensor for Bacillus anthracis spore detection in aqueous solution. The europium-modified polyacrylonitrile nanoparticles were readily combined with dipicolinic acid as a unique biomarker of B. anthracis, leading to high fluorescence emission. These nanoparticles enabled ratiometric detection without instrument-specific calibration due to the internal fluorescence reference. Additionally, the europium-modified polyacrylonitrile nanoparticle sensors exhibited a remarkable limit of detection (10pM) for dipicolinic acid and outstanding selectivity (160×) over aromatic ligands in aqueous solution. The ultrafine nanoparticle sensor showed a high capability for detecting anthrax due to the increased surface area-to-volume ratio and enhanced dispersibility.

Efficient intracellular delivery of camptothecin by silica/titania hollow nanoparticles.

Silica/titania hollow nanoparticles (HNPs) with 50 nm were fabricated by using the dissolution and redeposition method and modified with anti-[human epidermal growth factor receptor 2] monoclonal antibody (herceptin), and their application as camptothecin (CPT) delivery agents to human breast cancer SK-BR-3 cells was investigated. Although the diameter of herceptin-modified HNPs (HER-HNP) is smaller than that of other reported mesoporous silica nanoparticles, the extensive hollow cavity of HNPs (ca. 30 nm) allowed the loading of a large amount of CPT. CPT-loaded HER-HNP (HER-HNP-CPT) did not release CPT in phosphate-buffered saline over a period of 24 h, however, HER-HNP-CPT in a hydrophobic solvent released its entire load of CPT. In addition, HER-HNPs were efficiently internalized owing to their herceptin conjugation and optimized size. To evaluate in vitro antitumor efficacy, apoptosis/necrosis and viability of HER-HNP-CPT-treated cells were investigated. When the cells were treated with HER-HNP-CPT for 30 min, a few apoptotic cells were observed. After 24 h, the viability of HER-HNP-CPT-treated SK-BR-3 decreased to 60 %, which revealed highly efficient chemotherapy. However, CPT loaded into HNP or HER-HNP had no significant effects on the viability of macrophages. Judging from these data, HER-HNPs are very suitable for application in anticancer therapy. A HER-HNP-CPT drug delivery system offers a new direction for a hydrophobic anticancer drug carrier and can be expanded to practical applications with further studies.

Screen-printed fluorescent sensors for rapid and sensitive anthrax biomarker detection

Since the 2001 anthrax attacks, efforts have focused on the development of an anthrax detector with rapid response and high selectivity and sensitivity. Here, we demonstrate a fluorescence sensor for detecting anthrax biomarker with high sensitivity and selectivity using a screen-printing method. A lanthanide-ethylenediamine tetraacetic acid complex was printed on a flexible polyethersulfone film. Screen-printing deposition of fluorescent detecting moieties produced fluorescent patterns that acted as a visual alarm against anthrax.

Fluorescent boronic acid-modified polymer nanoparticles for enantioselective monosaccharide detection

We report the fabrication of new fluorescent boronic acid-modified polyacrylonitrile (B-PAN) nanoparticles for an enantioselective monosaccharide sensor. Polyacrylonitrile (PAN) nanoparticles of 50 nm diameter were synthesized by radical polymerization. After boronic acid modification, the B-PAN nanoparticles showed enhanced fluorescence due to a photo-induced electron transfer mechanism. The B-PAN nanoparticles enabled molecular recognition in aqueous solution owing to covalent bonds with diol-containing compounds, resulting in application for enantiomer detection of monosaccharides. The fluorescence intensity changed when B-PAN nanoparticles interacted with the enantiomers of monosaccharides, including D-/L-glucose, D-/L-galactose, and D-/L-fructose. The B-PAN nanoparticles provide a new direction for the development of enantioselective monosaccharide sensors and could be subsequently expanded to a platform of versatile fluorescence sensors.