ABSTRACT
The removal of toxic dye pigments from the environment is of utmost importance since even trace amounts of these pollutants can lead to harmful impacts on ecosystems. Heterogeneous photocatalysis is a potential technique for eliminating microbiological, inorganic, and organic pollutants from wastewater. Here, we report the band gap alteration of ZnO by making its composites with CuSe to enhance photocatalytic activity. The purpose is to develop metal oxide nanocomposites (ZnO/CuSe) as an effective and efficient material for the photodegradation of methyl blue. The photocatalysts, ZnO nanorods, CuSe, and ZnO/CuSe nanocomposites of different weight ratios were synthesized by the simple and cost-effective technique of precipitation. UV-Vis spectra verified that the ZnO/CuSe photocatalyst improved absorption in the visible region. The optical bandgap of ZnO/CuSe nanocomposites reduced from 3.37 to 2.68 eV when CuSe concentration increased from 10 to 50%. ZnO/CuSe composites demonstrated better photocatalytic activity than ZnO when exposed to UV-visible light. The pure ZnO nanorods could absorb UV light and the nanocomposites could absorb visible light only; this was attributed to the transfer of excited high-energy electrons from ZnO to CuSe.
ABSTRACT
The encapsulation of plant extract in nanomatrices has limitations due to its adhesion to walls, size control, high cost and long durations that results in low yield. Macroscale and microscale level techniques for development of micro/nanoparticles may impact the encapsulation of plant extract. This study aimed to evaluate the relative efficiency of microscale and macroscale techniques for encapsulation of plant extract, which is not compared yet. Keeping this in view, encapsulation of Calotropis gigantea leaves extract (CaG) was attained in silver-conjugated poliglusam nanomatrices (POL/Ag) to induce apoptosis in invasive ductal carcinoma (IDC) cells. The ethanolic CaG extract was prepared using percolation method and characterized by chemical tests for its active phytochemical compounds. The droplet-based microfluidic system was utilized as microscale encapsulation technique for CaG in nanomatrices at two different aqueous to oil flow rate ratios 1.0:1.5, and 1.0:3.0. Moreover, conventional batch system was utilized as macroscale encapsulation technique consisted of hot plate magnetic stirrer. The prepared nanomatrices were analysed for antioxidant activity using DPPH test and for cytotoxicity analysis using MCF-7 cells. The characteristic peaks of UV-Vis, FTIR and XRD spectrum confirmed the synthesis of CaG(POL/Ag) by both the encapsulation methods. However, microfluidic system was found to be more expedient because of attaining small and uniform sized silver nanoparticles (92 ± 19 nm) at high flow rate and achieving high encapsulation efficiency (80.25%) as compared to the conventional batch method (52.5%). CaG(POL/Ag) nanomatrices found to have significant antioxidant activity (p = 0.0014) against DPPH radical scavenging activity. The CaG(POL/Ag) of the smallest sized formulated by the microfluidic system has also shown the highest cytotoxicity (90%) as compared to batch method (70%) at 80 µg/mL. Our results indicate that the microscale technique using microfluidic system is a more efficient method to formulate size-controlled CaG(POL/Ag) nanomatrices and achieve high encapsulation of plant extract. Additionally, CaG(Pol/Ag) was found to be an efficient new combination for inducing potent (p < 0.0001) apoptosis in IDC cells. Therefore, CaG(Pol/Ag) can be further tested as an anti-cancer agent for in-vivo experiments.
