Sojin Kim

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.

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.

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.

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.

Highly Fluorescent Amidine/Schiff Base Dual-Modified Polyacrylonitrile Nanoparticles for Selective and Sensitive Detection of Copper Ions in Living Cells

Highly fluorescent surface modified polyacrylonitrile nanoparticles (PAN NPs) of 50 nm diameter were fabricated for selective Cu(2+) sensing. After surface modification, the PAN NPs were converted to amidine/Schiff base dual-modified PAN nanoparticles (tPAN NPs) with a Cu(2+) sensing property and high QY (0.19). The selectivity of tPAN NPs for Cu(2+) is much higher than that of other metal ions due to the fact that amidine group on the surface of tPAN NPs has a higher binding affinity with Cu(2+). The effect of other metal ions on the fluorescence intensity of the tPAN NPs was also studied, and other metal ions showed a low interference response in the detection of Cu(2+). Furthermore, as a metal ion chelator, ethylenediaminetetraacetate can competitively interact with Cu(2+) to recover the quenched fluorescence of tPAN NPs. The tPAN NPs are easily introduced into cells and exhibit low toxicity, enabling their use as a fluorescence sensor for Cu(2+) in living cells. The tPAN NPs provide a new direction for the development of copper ion sensors in living cells.

Enhanced electrorheological performance of barium-doped SiO2/TiO2 hollow mesoporous nanospheres

Barium-doped SiO2/TiO2 hollow mesoporous nanospheres (Ba-HNSs) exhibited 22.5 times higher maximum yield stress than commercial BaTiO3 nanopowders, and 4 times faster ER response than pristine. These superior ER properties were originated from the unique hollow mesoporous structure and high dielectric properties of BaTiO3 in the Ba-HNSs.

Inkjet-printed polyaniline patterns for exocytosed molecule detection from live cells

Polyaniline (PANi) patterns on flexible substrate are fabricated for biomolecule detection from live cells. PANi patterns are prepared by inkjet printing on polyethylene terephthalate film. Subsequently, arginine-glycine-aspartate (RGD) peptide is immobilized on the PANi pattern to selectively adhere cells. Rat pheochromocytoma PC12 cells are cultured on the RGD-immobilized PANi pattern, and patterned with high selectivity and growth. Additionally, the cells show focal adhesion on the RGD-immobilized PANi pattern, which are confirmed with vinculin staining and scanning electron microscopic images. To monitor dynamic biomolecular release from PC12 cells, RGD-immobilized PANi pattern is used for a real-time electrical signal detector. RGD-immobilized PANi patterning and sensing system represents outstanding ability to translate and amplify exocytosis molecules into a detectable signal as a transducer.

Fabrication of barium- and strontium-doped silica/titania hollow nanoparticles and their synergetic effects on promoting neuronal differentiation by activating ERK and p38 pathways.

Pristine, barium-doped, and strontium-doped hollow nanoparticles (p-HNPs, Ba-HNP, and Sr-HNP; HNPs) are prepared by sonication-mediated etching and redeposition (SMER) method and alkali-earth-metal hydroxide solution treatment. The HNPs are investigated to facilitate synergetic neuronal differentiation through alkali-earth-metal doping and in conjunction with nerve growth factor (NGF). PC12 cells are used as model cells for neuronal differentiation. The differentiation efficiency is improved in the presence of the HNPs+NGF, and the neurite length is in the order of Sr-HNP+NGF > Ba-HNP+NGF > p-HNP+NGF > NGF. Silica/titania have increasing effect on both differentiation efficiency and neurite length, and doped barium/strontium influences additional elongation of the average neurite length. Take advantage of hollow structure, NGF is encapsulated into HNPs, and they are further applied for directly inducing differentiation. The maximum differentiation efficiency is 67% in presence of the NGF-encapsulated Sr-HNP, which was 1.3 times higher than previous research. Furthermore, the neurite length is also 2.7 times higher than MnO2 decorated poly(3,4-ethylenedioxythiophene) nanoellipsoids. Ba- and Sr-HNP may offer a possibility for novel application of metal-hybrid nanomaterials for cell differentiation, and can be expanded to other cellular applications.

Use of a decoration method on silica nanoparticles to determine element-dependent mitochondrial dysfunction

To accurately assess the element-dependent cytotoxicity, nanomaterials with fixed sizes and shapes are required. Here, we fabricated six different elemental nanodomains (MnO2, Fe2O3, CuO, ZnO, CeO2, and Se) on silica nanoparticles with the same physical properties, and determined their toxicity based on the mitochondrial dysfunction.