Laura Carson

Hydroxyapatite grafted carbon nanotubes and graphene nanosheets: promising bone implant materials.

In the present study, hydroxyapatite (HA) was successfully grafted to carboxylated carbon nanotubes (CNTs) and graphene nanosheets. The HA grafted CNTs and HA-graphene nanosheets were characterized using FT-IR, TGA, SEM and X-ray diffraction. The HA grafted CNTs and graphene nanosheets (CNTs-HA and Gr-HA) were further used to examine the proliferation and differentiation rate of temperature-sensitive human fetal osteoblastic cell line (hFOB 1.19). Total protein assays and western blot analysis of osteocalcin expression were used as indicators of cell proliferation and differentiation. Results indicated that hFOB 1.19 cells proliferate and differentiate well in treatment media containing CNTs-HA and graphene-HA. Both CNTs-HA and graphene-HA could be promising nanomaterials for use as scaffolds in bone tissue engineering.

Synthesis, characterization and stability of chitosan and poly(methyl methacrylate) grafted carbon nanotubes

The single walled carbon nanotubes (CNTs) were effectively functionalized through grafting with chitosan (CTS) and poly(methyl methacrylate) (PMMA). Prior to grafting reaction, the carboxylated SWNCTs (SWNCTs-COOH) were obtained by treating pristine CNTs with a mixture of 3:1 (v/v) H(2)SO(4) and HNO(3), and the successive treatment of SWNCTs-COOH with SOCl(2) yielded the acylated CNTs (CNTs-COCl). The functionalized derivatives of CNTs were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. Both CTS and PMMA grafted CNTs showed better dispersability in acetic acid and tetrahydrofuran, in addition to higher stability in solution.

Synthesis and characterization of Zinc/Chitosan-Folic acid complex

Therapeutic drug delivery systems using polymeric materials is an emerging field of research. However, the use of certain polymers has gained much-needed attention by the researchers due to their low toxic nature. In recent years, chitosan has gained popularity as a potential biodegradable polymer that can be used as a component in drug delivery systems. In this study, we synthesized a chitosan derivative that is composed of both folic acid and zinc and may serve as a viable component of a drug delivery system. The results of Fourier Transform Infrared Spectroscopy (FTIR), solid-state 13C Nuclear Magnetic Resonance Spectroscopy (NMR) and UV-visible Spectroscopy demonstrated a substantial difference between chitosan and ZnS/Chitosan-Folic acid derivative. The results were also confirmed using Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM-EDS) techniques. The average particle size of the ZnS/Chitosan-Folic acid system was measured to be 463.67 ± 5.76 nm, showing that the product is within the nano-size range.

Abstract 3931: Progesterone and estrogen affect the expression and secretion of heparin binding epidermal growth factor like growth factor (HB-EGF) in RL95-2 cells, an endometrial cancer cell line

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Endometrial cancer is one of the most common gynecological cancers. Heparin Binding Growth Factor-like Growth Factor exerts acute effects on cancer cells; in that it induces and promotes proliferation and hence the pathogenesis and progression of endometrial cancer. Steroid hormones directly or indirectly affect the expression of HB-EGF and may thus play a role in the malignant transformation of endometrial cells. The aim of this project is therefore to evaluate the effects of progesterone (P4) and estrogen (E2) treatments on the expression and secretion of HB-EGF in endometrial cancer cells. We hypothesized that P4 will reduce HB-EGF expression and secretion while E2 will increase its expression and secretion. To test our hypothesis, an endometrial cell line, RL95-2, was treated for four days asfollows: (1) 10−8M E2, (2)10−6M P4, (3) 10−8M E2 + 10−6M P4 (4) 10−8M E2 in two days followed by 10−6M P4 and (5) Control. Immunocytochemistry (ICC), ELISA and western blot analysis were performed to evaluate the secretion and expression of HB-EGF in RL95-2 cells. Western blot analysis and ICC showed a consistently enhanced expression of HB-EGF in cells treated with E2 and in cells treated with E2 followed by P4 relative to the control groups. Alternatively, cells treated with P4 showed a down-regulation of HB-EGF expression relative to the control group. ELISA analysis showed high secretion of HB-EGF in cells treated with E2 and cells treated with E2 followed by P4 relative to the control groups. The secretion of HB-EGF was lower in cells treated with P4 alone compared to the control. In sum, there is an acute effect of E2 and P4 on the expression and secretion of HB-EGF and thus consequently may affect endometrial cancer cell proliferation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3931. doi:1538-7445.AM2012-3931

Abstract 4773: Synergistic effects of chitosan and docosahexanoic acid on osteopontin expression and secretion in an ovarian cancer cell line, SKOV-3

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Current treatment for the deadliest gynecological disease, ovarian cancer, is surgical debulking followed by chemotherapy or radiotherapy, but reoccurrence is still significantly high. Hence, there is a need for alternative treatments, and more specifically a natural therapeutic product. Recent studies have shown that natural products, such as chitosan and omega-3 fatty acids, inhibit the proliferation of cancer cells. Osteopontin (OPN), a cell surface and secretory glycoprotein, has been implicated as an important biomarker for ovarian cancer. Therefore, the objective of this study was to determine the effect of chitosan and DHA on OPN secretion and expression levels in an ovarian cancer cell line, SKOV-3 cells. We hypothesized that chitosan and DHA will decrease OPN expression in a dose-dependent manner. To test our hypothesis, SKOV-3 cells were treated with (a) 0 ng/mL, (b) 1% acetic acid; (c) 250 ng/mL of chitosan, (d) 100 µM of DHA, (e) 250 ng/mL of chitosan + 100 µM of DHA for 24 and 48 hours. Western Blot analysis and immunocytochemistry were performed to observe the expression and localization of OPN, while an ELISA was used to determine OPN secretion. Quantitative RT-PCR was also performed to determine OPN mRNA expression in the treated cells. Osteopontin (OPN) protein was localized on the surface of SKOV-3 cells and its expression decreased in both chitosan and DHA-treated cells. Furthermore in cells treated with both chitosan and DHA, there was an even greater decrease in OPN expression. The synergistic effects of chitosan and DHA suggest that these natural products may serve as potential natural treatment for ovarian cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4773. doi:1538-7445.AM2012-4773

Abstract 4325: Localization and expression of osteopontin in a chitosan-treated ovarian cancer cell line, SKOV-3

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Ovarian cancer is the deadliest gynecological malignancy and despite current treatments, such as chemotherapy and radiotherapy, reoccurrence of this deadly malignancy is high. Although elevated levels of osteopontin (OPN), a phosphorylated glycoprotein, are always present in the ovaries, recent studies have implicated osteopontin (OPN) protein as a novel biomarker for ovarian cancer. Early detection of ovarian cancer is imperative, and furthermore, novel treatments with fewer adverse effects than current treatments of chemotherapy and radiation, are currently being investigated. Chitosan, a natural polysaccharide that is biodegradable and biocompatible, may serve as a potential alternative treatment for ovarian cancer, and may function by regulating OPN expression. Therefore, the objective of this study was to determine the effects of chitosan on the expression and localization of OPN in SKOV-3 cells. It was hypothesized that the expression of OPN protein will be down-regulated in a dose-dependent manner. To test this hypothesis, SKOV-3 cells were treated with 0, 50, 100, 250, and 500, ng/mL of chitosan for 48 hours. An MTT assay was performed to determine cell viability and proliferation rate. Cells were harvested; total protein was isolated and then subjected to SDS-PAGE and Western blot analysis. The localization of OPN was determined using immunocytochemistry, after chitosan treatment of SKOV-3 cells on two-chamber slides for 48 hours. The expression of OPN decreased in SKOV-3 cells in a dose-dependent manner. In addition, cell proliferation tended to decrease with increasing dose of chitosan. These data indicate that chitosan may inhibit SKOV-3 cell proliferation by decreasing OPN production and secretion. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4325. doi:10.1158/1538-7445.AM2011-4325

Surface Chemistry of Functionalized Carbon Nanotubes

Carbon nanotubes (CNTs) have been well recognized as a promising material due to their extraordinary mechanical, thermal and electrical properties for diverse applications. However, their behavior of hydrophobicity and chemical inertness, which cause tangling or poor dispersion, limits their commercial applications. Towards this technical issue, it has been found that the functionalization of CNTs by surface modification using chemical reactants [1-4] is an effective way to improve the dispersion degrees [5]. In order to have a better understanding of the mechanism, a characterization of the surface chemistry of various functionalized CNTs is performed in this work.

Characterization of chemical coating on the functionalized carbon nanotubes

Carbon nanotubes (CNTs) have received considerable attention due to their extraordinary properties of strength, toughness, as well as thermal and electrical conductivities. They are ideal fillers for polymer nanocomposites to enhance the composite physical and mechanical properties. In order to overcome the problem of tangling caused by CNT intrinsic van der Waals forces during the composite fabrication, a chemical functionalization process was introduced [1–4] to achieve a better dispersion degree, which is a critical factor dominating the composite performance [5]. However, the coating microstructure remains unidentified. In this work, we present a characterization of the chemical coating on the functionalized CNTs using analytical TEM. The experimental material, CNT-COCl, was oxidized with mixed sulfuric and nitric acids, and then further reacted with thionyl chloride SOCl2. The CNT sample was deposited on Cu grids coated with carbon support film, and observed in a FEI Tecnai G2 F20 at 200 kV, equipped with a Fischione ultra-high resolution STEM HAADF detector, Oxford instruments EDS detector, and a post-column Gatan Image Filter (GIF). Fig. 1(a) is a typical TEM image of the functionalized CNTs, with coatings on the surface. From the Z-contrast image collected by the HAADF detector in the STEM mode, the coatings are more clearly revealed, as shown in (b). It is seen that most of the CNTs are coated with thick layers, while only a few areas have thin layers or are even uncoated. Particles with extremely high brightness, as indicated by arrowheads, are identified as metal particles of Co that give rise to high scattering contrast. The EDS analysis, as shown in (c), reveals the chemical compositions of C-S-Cl-O of the coating layers, consistent with the materials used during the functionalization process. The Cu signal originates from the grid bar. Fig. 1 (a) TEM image; (b) Z-contrast image showing the coatings on the CNT surface; (c) EDS spectrum showing the composition. In order to identify the chemical distribution, elemental mapping was performed by the three-window method using GIF in the EFTEM mode. Fig. 2(a) is a zero-loss image, and the elemental maps of O, Cl and S are shown in (b–d), respectively. Basically, all O-Cl-S elements distribute over the areas around the CNTs, while there are some small particles enriched in S, as highlighted by arrowheads in (d). A framed area in (a) is magnified in (e), with the carbon layers of the CNTs readily visible. Isolated surfactants discretely cover the vertical CNT, as indicated by arrowheads. The chemical coating provides an important role in facilitating excellent bonding with the polymer matrix [6]. Fig. 2 Zero-loss image (a) and EFTEM elemental maps of O, Cl and S in (b–d) respectively. The framed area in (a) is magnified in (e). Arrowheads indicate the surface coating on this CNT.