Magnetic and Cytotoxicity Properties of La1−xSrxMnO3(0 ≤ x ≤ 0.5) Nanoparticles Prepared by a Simple Thermal Hydro-Decomposition

This study reports the magnetic and cytotoxicity properties of magnetic nanoparticles of La1−xSrxMnO3(LSMO) withx = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 by a simple thermal decomposition method by using acetate salts of La, Sr, and Mn as starting materials in aqueous solution. To obtain the LSMO nanoparticles, thermal decomposition of the precursor was carried out at the temperatures of 600, 700, 800, and 900 °C for 6 h. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM, and SEM. Structural characterization shows that the prepared particles consist of two phases of LaMnO3(LMO) and LSMO with crystallite sizes ranging from 20 nm to 87 nm. All the prepared samples have a perovskite structure with transformation from cubic to rhombohedral at thermal decomposition temperature higher than 900 °C in LSMO samples ofx ≤ 0.3. Basic magnetic characteristics such as saturated magnetization (MS) and coercive field (HC) were evaluated by vibrating sample magnetometry at room temperature (20 °C). The samples show paramagnetic behavior for all the samples withx = 0 or LMO, and a superparamagnetic behavior for the other samples havingMSvalues of ~20–47 emu/g and theHCvalues of ~10–40 Oe, depending on the crystallite size and thermal decomposition temperature. Cytotoxicity of the synthesized LSMO nanoparticles was also evaluated with NIH 3T3 cells and the result shows that the synthesized nanoparticles were not toxic to the cells as determined from cell viability in response to the liquid extract of LSMO nanoparticles

An investigation of the biological activities of rainbow trout Ela4-peptide of pro-IGF-I in human cancer cells

E-peptides are the C-terminal domain of pro-IGFs, which are proteolytically cleaved from the pro-IGFs and subsequently co-secreted with mature IGFs. E-peptide was thought to be biological inactive until recently. Although, many biological activities have been shown to be associated with E-peptides in both non-transformed and transformed cells in recent years, very little is known about the mode of action of these peptides at the molecular level. ^ The specific goals of this thesis are to characterize the biological activities and to explore the potential molecular mechanism of rainbow trout Ela4-peptide using a well-characterized human breast cancer cell line, MDA-MB-231, as the cell model of the study. Results of these studies reveal that trout Ela4-peptide possesses activities in inducing unique cell morphological change, promoting cell attachment, and reducing cell invasion on MDA-MB-231 cells. The mechanism of Ela4-peptide in promoting cell attachment is likely mediated via (1) the binding of Ela4-peptide to the integrin receptors (α2 and β1) and (2) the induction of adhesion molecule and adhesion cell membrane receptor (fibronectin 1 and laminin receptor). The regulation of fibronectin 1 gene expression by Ela4-peptide is potentially mediated via the FAK/MAPK pathways. Ela4 peptide is also believed to reduce invasion by (1) suppressing the expression of proteases, uPA and tPA via the FAK/MAPK pathways and (2) promoting cell adhesion. Most anti-invasive, anti-metastatic agents function in either enhancing cell attachment or reducing the production of proteases. Since Ela4-peptide possesses both functions, it perhaps can be used as an effective anti-invasive, anti-metastatic agent. The information obtained from this dissertation has provided the foundation for understanding the biological activities as well as molecular mechanism of Ela4-peptide action. Further studies conducted in this system may lead to the development of a new generation of therapeutic agents for the management of human cancers.