Chia-Liang Cheng

Endocytic carboxylated nanodiamond for the labeling and tracking of cell division and differentiation in cancer and stem cells

Nanodiamond (ND) is carbon nanomaterial developing for biological applications in recent years. In this study, we investigated the location and distribution of 100 nm carboxylated ND particles in cell division and differentiation. ND particles were taken into cells by macropinocytosis and clathrin-mediated endocytosis pathways. However, the cell growth ability was not altered by endocytic ND particles after long-term cell culture for 10 days in both A549 lung cancer cells and 3T3-L1 embryonic fibroblasts. ND particles were equal separating into two daughter cells of cell division approximately. Finally, the cell retained a single NDs cluster in cytoplasm after sub-cultured for several generations. Interestingly, NDs clusters were carried inside of cell but without inducing damages after long-term cell culture. Moreover, ND particles did not interfere with the gene or protein expressions on the regulation of cell cycle progression and adipogenic differentiation. Together, these findings provide that endocytic ND particles are non-cytotoxic in cell division and differentiation, which can be applied for the labeling and tracking of cancer and stem cells.

Covalent linkage of nanodiamond-paclitaxel for drug delivery and cancer therapy

A nanoparticle-conjugated cancer drug provides a novel strategy for cancer therapy. In this study, we manipulated nanodiamond (ND), a carbon nanomaterial, to covalently link paclitaxel for cancer drug delivery and therapy. Paclitaxel was bound to the surface of 3-5 nm sized ND through a succession of chemical modifications. The ND-paclitaxel conjugation was measured by atomic force microscope and nuclear magnetic resonance spectroscopy, and confirmed with infrared spectroscopy by the detection of deuterated paclitaxel. Treatment with 0.1-50 microg ml(-1) ND-paclitaxel for 48 h significantly reduced the cell viability in the A549 human lung carcinoma cells. ND-paclitaxel induced both mitotic arrest and apoptosis in A549 cells. However, ND alone or denatured ND-paclitaxel (after treatment with strong alkaline solution, 1 M NaOH) did not induce the damage effects on A549 cells. ND-paclitaxel was taken into lung cancer cells in a concentration-dependent manner using flow cytometer analysis. The ND-paclitaxel particles were located in the microtubules and cytoplasm of A549 cells observed by confocal microscopy. Furthermore, ND-paclitaxel markedly blocked the tumor growth and formation of lung cancer cells in xenograft SCID mice. Together, we provide a functional covalent conjugation of ND-paclitaxel, which can be delivered into lung carcinoma cells and preserves the anticancer activities on the induction of mitotic blockage, apoptosis and anti-tumorigenesis.

Nanodiamonds for optical bioimaging

Diamond has received increasing attention for its promising biomedical applications. The material is highly biocompatible and can be easily conjugated with bioactive molecules. Recently, nanoscale diamond has been applied as light scattering labels and luminescent optical markers. The luminescence, arising from photoexcitation of colour centres, can be substantially enhanced when type Ib diamond nanocrystals are bombarded by a high-energy particle beam and then annealed to form negatively charged nitrogen-vacancy centres. The centre absorbs strongly at 560 nm, fluoresces efficiently in the far-red region and is exceptionally photostable (without photoblinking and photobleaching). It is an ideal candidate for long-term imaging and tracking in complex cellular environments. This review summarizes recent advances in the development of fluorescent nanodiamonds for optical bioimaging with single particle sensitivity and nanometric resolution.

Direct and in vitro observation of growth hormone receptor molecules in A549 human lung epithelial cells by nanodiamond labeling

This letter presents direct observation of growth hormone receptor in one single cancer cell using nanodiamond-growth hormone complex as a specific probe. The interaction of surface growth hormone receptor of A549 human lung epithelial cells with growth hormone was observed using nanodiamond’s unique spectroscopic signal via confocal Raman mapping. The growth hormone molecules were covalent conjugated to 100nm diameter carboxylated nanodiamonds, which can be recognized specifically by the growth hormone receptors of A549 cell. The Raman spectroscopic signal of diamond provides direct and in vitro observation of growth hormone receptors in physiology condition in a single cell level.

The effects of the bacterial interaction with visible-light responsive titania photocatalyst on the bactericidal performance

Bactericidal activity of traditional titanium dioxide (TiO2) photocatalyst is effective only upon irradiation by ultraviolet light, which restricts the potential applications of TiO2 for use in our living environments. Recently carbon-containing TiO2 was found to be photoactive at visible-light illumination that affords the potential to overcome this problem; although, the bactericidal activity of these photocatalysts is relatively lower than conventional disinfectants. Evidenced from scanning electron microscopy and confocal Raman spectral mapping analysis, we found the interaction with bacteria was significantly enhanced in these anatase/rutile mixed-phase carbon-containing TiO2. Bacteria-killing experiments indicate that a significantly higher proportion of all tested pathogens including Staphylococcus aureus, Shigella flexneri and Acinetobacter baumannii, were eliminated by the new nanoparticle with higher bacterial interaction property. These findings suggest the created materials with high bacterial interaction ability might be a useful strategy to improve the antimicrobial activity of visible-light-activated TiO2.

An effective surface-enhanced Raman scattering template based on a Ag nanocluster–ZnO nanowire array

An effective surface-enhanced Raman scattering (SERS) template based on a 3D hybrid Ag nanocluster (NC)-decorated ZnO nanowire array was fabricated through a simple process of depositing Ag NCs on ZnO nanowire arrays. The effects of particle size and excitation energy on the Raman scattering in these hybrid systems have been investigated using rhodamine 6G as a standard analyte. The results indicate that the hybrid nanosystem with 150 nm Ag NCs produces a larger SERS enhancement factor of 3.2 x 10(8), which is much higher than that of 10 nm Ag NCs (6.0 x 10(6)) under 532 nm excitation energy. The hybrid nanowire arrays were further applied to obtain SERS spectra of the two-photon absorption (TPA) chromophore T7. Finite-difference time-domain simulations reveal the presence of an enhanced field associated with inter-wire plasmon coupling of the 150 nm Ag NCs on adjacent ZnO nanowires; such a field was absent in the case of the 10 nm Ag NC-coated ZnO nanowire. Such hybrid nanosystems could be used as SERS substrates more effectively than assembled Ag NC film due to the enhanced light-scattering local field and the inter-wire plasmon-enhanced electromagnetic field.

Organic functionalization of ultradispersed nanodiamond: synthesis and applications

This work describes the chemical modification of ultradispersed nanodiamond results in the enrichment of the surface hydroxyl groups as by FT-IR, TGA, RGA-MS and XRD measurements. These hydroxyl groups can be conveniently functionalized with long chain alcohols (oxyhexanol) for easy manipulation of different functional groups. The surface loading of the oxyhexanol groups were found to be 0.13 mmol/g of nanodiamond. The functionalities on the surface of the modified nanodiamond afford a new solid phase for the synthesis of peptides to facilitate the covalent attachment of drug molecules. The conjugation of chiral ligands with a nanodiamond yields a new enantioselective heterogeneous catalyst that exhibits moderate to good enantioselectivity in the asymmetric aldol reaction.

Size-dependent surface CO stretching frequency investigations on nanodiamond particles

In this work, the spectroscopic properties of surface functionalized nanodiamond particles are investigated via Fourier transform infrared spectroscopy. The functionalization of the nanodiamond surface was achieved chemically using strong acid treatment method. The size dependent C=O stretching frequency (between 1680 and 1820 cm(-1)) are studied for particle diameter sizes from the 5 to 500 nm range. The surface C=O stretching frequencies at approximately 1820 cm(-1), for large particle size (500 nm), down shifted to 1725 cm(-1) (5 nm) with decreasing particle sizes. We attributed the shift as a result of hydrogen bond formation between the COOH groups in the carboxylated nanodiamond surfaces. Particle size was characterized with dynamic light scattering method and surface morphology of the particles was investigated with scanning electron microscopy. The influence of pH value on C=O stretching frequency is also analyzed. This finding affords useful information for the studying of surface functionalized nanodiamonds with implications for their interaction with biomolecules.

Growth of faceted, ballas-like and nanocrystalline diamond films deposited in CH4/H2/Ar MPCVD

Abstract The influence of Ar addition to CH 4 /H 2 plasma on the crystallinity, morphology and growth rate of the diamond films deposited in MPCVD was investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. X-Ray diffraction patterns indicate that diamond films of strong (111) and weak (400) texture are produced in these samples. Faceted diamond gradually turns into ballas-like diamond with graphitic inclusions when the Ar concentration increases to above 30 vol.%, as indicated by Raman spectra. As the Ar concentration goes above 90 vol.%, nanocrystalline diamond films are formed, characterized by a 1150-cm −1 peak in the Raman spectra and morphology observation. Diamond growth by CH 3 or by C 2 mechanism is proposed to interpret the change in the growth rate of diamond films with the variation of Ar content in the plasma.

Alpha-bungarotoxin binding to target cell in a developing visual system by carboxylated nanodiamond

Biological molecules conjugating with nanoparticles are valuable for applications including bio-imaging, bio-detection, and bio-sensing. Nanometer-sized diamond particles have excellent electronic and chemical properties for bio-conjugation. In this study, we manipulated the carboxyl group produced on the surface of nanodiamond (carboxylated nanodiamond, cND) for conjugating with alpha-bungarotoxin (α-BTX), a neurotoxin derived from Bungarus multicinctus with specific blockade of alpha7-nicotinic acetylcholine receptor (α7-nAChR). The electrostatic binding of cND-α-BTX was mediated by the negative charge of the cND and the positive charge of the α-BTX in physiological pH conditions. Sodium dodecyl sulfate-polyacrylamide gel analysis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF-MS) spectra displayed that α-BTX proteins were conjugated with cND particles via non-covalent bindings. The green fluorescence of the cND particles combining with the red fluorescence of tetramethylrhodamine-labeled α-BTX presented a yellow color at the same location, which indicated that α-BTX proteins were conjugated with cND particles. Xenopus laeviss oocytes expressed the human α7-nAChR proteins by microinjection with α7-nAChR mRNA. The cND-α-BTX complexes were bound to α7-nAChR locating on the cell membrane of oocytes and human lung A549 cancer cells analyzed by laser scanning confocal microscopy. The choline-evoked α7-nAChR-mediated inward currents of the oocytes were blocked by cND-α-BTX complexes in a concentration-dependent manner using two-electrode voltage-clamp recording. Furthermore, the fluorescence intensity of cND-α-BTX binding on A549 cells could be quantified by flow cytometry. These results indicate that cND-conjugated α-BTX still preserves its biological activity in blocking the function of α7-nAChR, and provide a visual system showing the binding of α-BTX to α7-nAChR.