| AVS 62nd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Friday Sessions |
| Session 2D+EM+IS+NS+PS+SP+SS-FrM |
| Session: | Surface Chemistry of 2D Materials: Functionalization, Membranes, Sensors |
| Presenter: | Ankur Gupta, University of Central Florida |
| Authors: | A. Gupta, University of Central Florida T. Selvan, University of Central Florida S. Das, University of Central Florida S. Seal, University of Central Florida |
| Correspondent: | Click to Email |
The human body is a complex system capable of defending in adverse conditions. A classic example of such complex process is balanced equilibrium production between pro-oxidant and antioxidant in cells. However, when this equilibrium is disturbed, production of free radicals such as superoxide and nitric oxide strengthen, and causes serious cellular damages. Furthermore, myeloperoxidase (MPO) is released during the oxidative burst. This MPO combines with hydrogen peroxide (H2O2) and Cl- and generate hypochlorous acid (HOCl). This is a short-lived and powerful diffusible oxidant strong oxidizer and could react with O2- to produce OH·. Therefore, in physiological condition HOCl has a major role as a potent microbicidal agent in the immune defense; however, during the oxidative burst HOCl not only damage healthy tissue and generate radicals that are extremely reactive. Therefore, monitoring of the production of free radicals at the cellular level is important for diagnostic purpose. Over past years, several material have been used to develop sensors for free radical detection such as cerium oxide nanoparticles, MoS2 nanosheets and nanoparticles. However, detection of free radicals at cellular level is still a challenge.
In this attempt, layered molybdenum disulfide (MoS2) were synthesized via hydrothermal method. SBA-15 polymer template were utilized during hydrothermal process to grow MoS2 around it to develop porosity. After the hydrothermal synthesis and washing, polymer template was removed by dissolving it in isopropanol which leaves high surface area layered MoS2 crystal. Wet chemical exfoliation of MoS2 were carried out in aqueous solution of PluronicÒ F-127 having hydrophobic and hydrophilic chains. PluronicÒ F-127 was used to bring down the buoyant density of MoS2. Non-templated nanosheets were synthesized as control. The exfoliated solution were centrifuged at 3000 rpm to remove large particle and supernatant was collected for density gradient ultracentrifugation (DGU). Separation of different thickness layers is carried out by DGU. Thickness sort MoS2 nanosheets were characterized using AFM, XPS, HRTEM, Raman and UV-Vis spectroscopy for structural and chemical analysis. XPS, HETEM and EFTEM analysis of nanosheets have illustrate the sulfur deficiency at the edges of the nanosheets. MoS2 nanosheets were deposited on glassy carbon electrode for cyclic-voltammetry and chronoamperometry measurements. Higher sensitivity and repeatability were demonstrated by nanosheets prepared via template method as compared to control for reactive oxygen and nitrogen species, and HOCl.