ABSTRACT
Despite the utilization of external magnetic field (MF) in promoting the intrinsic unique features of magnetic nanomaterials in many different applications has been reported, however the origin of MF-dependent electrochemical behaviors as well as the electrochemical response of analytes at the electrode in sensor applications is still not clear. In this report, the influence of MF on the electrolyte's physicochemical properties (polarization, mass transport, charge/electron transfer) and electrode's properties (conductivity, morphology, surface area, interaction, adsorption capability, electrocatalytic ability) was thoroughly investigated. Herein, the working electrode surface was modified with carbon spheres (CSs), magnetic nanoparticles (Fe3O4NPs), and their nanocomposites (Fe3O4@CSs), respectively. Then, they were directly used to enhance the electrochemical characteristics and response-ability of chloramphenicol (CAP). More interestingly, a series of various kinetic parameters related to the diffusion-controlled process of K3[Fe(CN)6]/K4[Fe(CN)6)] and the adsorption-controlled process of CAP were calculated at the bare electrode and the modified electrodes with and without the presence of MF. These parameters not only exhibit the crucial role of the modification of electrode surface with the proposed materials but also show positive impacts of the presence of external MF. Besides, the mechanism and hypothesis for the enhancements were proposed and discussed in detail, further demonstrating the development potential of using Fe3O4@CS nanocomposites with MF assistant for advanced energy, environmental, and sensor related-applications.
Subject(s)
Carbon , Chloramphenicol , Carbon/chemistry , Electrochemical Techniques , Electrodes , Electrolytes , Magnetic FieldsABSTRACT
BACKGROUND: Gastric cancer is one of the most leading causes of cancer death worldwide. Therefore, treatment studies have been being conducted, one of which is screening of novel agents from medicinal herbs. Elephantopus mollis Kunth (EM) belonging to Asteraceae family is a perennial herb with several therapeutic properties including anticancer activity. However, the effect of this species on gastric cancer has not been reported yet. In this study, cytotoxicity of different EM crude extracts was investigated on AGS gastric cancer cell line. Besides, the effects of extract on nuclear morphology, caspase-3 activation, and gene expression were also explored. RESULTS: The results showed that ethyl acetate extract exhibited a remarkably inhibitory ability (IC50 = 27.5 µg/ml) on the growth of AGS cells, while causing less toxicity to normal human fibroblasts. The extract also induced apoptotic deaths in AGS cells as evidenced by cell shrinkage, formation of apoptotic bodies, nuclear fragmentation, caspase-3 activation, and the upregulation of BAK and APAF-1 pro-apoptotic genes related to mitochondrial signaling pathway. Specifically, BAK and APAF-1 mRNA expression levels showed 2.57 and 2.71-fold increases respectively. CONCLUSIONS: The current study not only proved the anti-gastric cancer activity of EM ethyl acetate extract but also proposed its molecular mechanism. The extract could be a potential candidate for further investigation.
