Green synthesis of Au coated on ZnO nanoparticles using orange peel extract and its application for electrochemical detection of formaldehyde

We report the facile preparation of Au coated ZnO nanoparticles via a two-step green synthesis route. The aqueous of orange peel extract (OPE) was used both as biocomplexing and bioreducing agents, while the Zn(NO3)2 and HAuCl4 were employed as precursors. Initially, OPE was prepared to synthesize the ZnONPs, followed by the reduction of HAuCl4, generating Au coated on ZnO nanoparticles (Au/ZnONPs). The IR spectra at around 438.95 cm-1 confirmed the presence of Zn-O absorption in the nanoparticles, while it was not observed in the OPE. Further characterization using XRD and SEM-EDX indicated that the spherical of Au was successfully coated on the sponge-like structure of ZnO with the crystalline size of ZnONPs and Au/ZnONPs were 21.30 and 26.67 nm, respectively.  The modified Au/ZnONPs on graphite paste electrode showed the excellent electrochemical detection of formaldehyde solution by the linearity range from 1 to 100 mM (R2=0.9945) with LOD of 10.27 mM and RSD of 0.39%. In addition, the modified electrode showed high selectivity toward formaldehyde, instead of ethanol

Iridium oxide (IV) nanoparticle-based lateral flow immunoassay

Lateral flow biosensors are paper-based devices that allow the detection of different types of analytes with quickness, robustness and selectivity, without leaving behind paper sensors benefits as low-cost, recyclability and sustainability. Nanomaterials have been widely reported in lateral flow biosensors, offering new sensing strategies based on optical or electrical detection techniques. Looking for other advantageous nanomaterials, we propose for the first time the use of iridium oxide (IV) nanoparticles in lateral flow assays for the detection of human immunoglobulin as a model protein. These nanoparticles can be easily prepared and conjugated with biomarkers. Their dark blue color gives a high contrast against the white background of the strips being in this way excellent labels

Effect of Chemical Compounds in Wastes from Essential Oil Distillation on the Activity of E.coli

Effect of chemical compounds in the wastes of essential oil distillation including lime leaves, lemongrass leaves, ylang-ylang flower, and coriander seed on the activity of Escherichia coli has been performed. In this research, observation was done by using microbial fuel cell (using E.coli) with two compartments were connected by nafion membrane and zinc plats were used as electrodes which were connected by copper wire and multimeter. Energy production from the cell was shown from the generated current due to the E.coli's oxidation activity to the substrates (distillation wastes). Results from the research exhibited that chemical compounds in the lime leaves positively affected to the bacterial activity with the generated current present up to 20 µA. It is also observed that mass variation of the substrates significantly affected the current generation. Chemical compounds in the three other wastes were found to be not as effective as lime leaves because from the analysis of their methanol extracts by GC-MS indicated that these contained antibacterial compounds such as octadecanoic acid and rosifoliol. Conclusion from the research was not all of wastes from essential oil distillation have a potency to be used as substrates in the microbial fuel cell as some of these chemicals had an antibacterial property which negatively affected the E.coli bacterial activity in the cell.   Keywords : microbial fuel cell, Escherichia coli, waste of essential oil distillation

Synthesis of Polyclonal Antibodies against Aflatoxin B1

Polyclonal antibodies of aflatoxin B1 were successfully produced from New Zealand White female rabbits after immunization by the hapten of aflatoxin B1-carboxymethyl hydroxylamine hemihydrochloride (AFB1-CMO) conjugated with bovine serum albumin (BSA) as the antigen. The hapten was synthesized using the carbodiimide method with CMO as a linker. Absorption peaks at 362, 264, and 218 nm were observed as a result of characterization with UV-Vis spectroscopy, while IR spectroscopy showed peaks at 3448 cm-1 and 1642 cm-1 attributable to the hydroxyl and nitrile groups, respectively. Furthermore, mass spectrometry showed fragmentation at the m/z of 386, 368.2, and 310, which confirms that the hapten of AFB1-CMO was successfully synthesized. The hapten was then conjugated with BSA to serve as an antigen of AFB1 when it was injected into the rabbits. The specificity of the antigen towards its antibody and the confirmation of hapten-BSA conjugation were characterized using the dot blot immunoassay, which showed a BSA concentration of 1.74 mg/mL. Two weeks after the primary immunization by its antigen, agar gel precipitation testing showed that the rabbit blood serum had positive results for polyclonal antibodiest against AFB1 with the highest concentration of antibodiest of 2.19 mg/mL

Synthesis of Polyclonal Antibodies against Aflatoxin B1

Polyclonal antibodies of aflatoxin B1 were successfully produced from New Zealand White female rabbits after immunization by the hapten of aflatoxin B1-carboxymethyl hydroxylamine hemihydrochloride (AFB1-CMO) conjugated with bovine serum albumin (BSA) as the antigen. The hapten was synthesized using the carbodiimide method with CMO as a linker. Absorption peaks at 362, 264, and 218 nm were observed as a result of characterization with UV-Vis spectroscopy, while IR spectroscopy showed peaks at 3448 cm-1 and 1642 cm-1 attributable to the hydroxyl and nitrile groups, respectively. Furthermore, mass spectrometry showed fragmentation at the m/z of 386, 368.2, and 310, which confirms that the hapten of AFB1-CMO was successfully synthesized. The hapten was then conjugated with BSA to serve as an antigen of AFB1 when it was injected into the rabbits. The specificity of the antigen towards its antibody and the confirmation of hapten-BSA conjugation were characterized using the dot blot immunoassay, which showed a BSA concentration of 1.74 mg/mL. Two weeks after the primary immunization by its antigen, agar gel precipitation testing showed that the rabbit blood serum had positive results for polyclonal antibodiest against AFB1 with the highest concentration of antibodiest of 2.19 mg/mL

Co-Solvent Free Electrochemical Synthesis of Biodiesel Using Graphite Electrode and Waste Concrete Heterogeneous Catalyst: Optimization of Biodiesel Yield

This study optimized a co-solvent free electrochemical method for biodiesel synthesis using graphite electrode and waste concrete heterogeneous catalyst. Various parameters were evaluated, including: applied voltage (9.6, 14.4, 19.2 V), catalyst particle size uniformity (unfiltered and filtered with 150 mesh), and reaction time (15, 30, 120, 240 min). The results obtained 100% FAME content and 78.51% of biodiesel yield that were achieved at 14.4 V within 30 min using filtered catalyst and cooking oil feedstock. However, a slight decline was observed with the use of waste cooking oil. This optimized method offers a reliable and simple condition for mass biodiesel production. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Biofabricated SnO2 nanoparticles using Red Spinach (Amaranthus tricolor L.) extract and the study on photocatalytic and electrochemical sensing activity

Biofabrication of SnO _2 nanoparticles (SnO _2 NPs) using Amaranthus tricolor L .) extract has been conducted. Synthesis of the nanoparticles was conducted by refluxing tin chloride dihydrate as SnO _2 precursor followed by calcination at 400 °C. The formation of SnO _2 NPs was identified from UV-Visible spectrophotometric analysis and particle size analyzer. The resulting materials were characterized by x-ray diffraction (XRD), Fourier-Transform Infra-Red (FTIR), scanning electron microscope-energy dispersive x-ray (SEM-EDS), transmission electron microscope (TEM), and diffuse reflectance UV-Visible (UV-DRS). Photocatalytic evaluation of SnO _2 NPs was carried out in a photodegradation of bromophenol blue (BPB) under photocatalytic and photooxidation mechanism with the presence of H _2 O _2 . Physicochemical analyses confirm the formation of SnO _2 NPs providing the capability to act as photoactive material. The photocatalytic activity studied by UV-Visible spectrophotometric analysis and high performance liquid chromatography (HPLC) revealed the superior activity of the nanoparticles for decomposition of BPB. The decomposition rate of BPB under photooxidation mechanism is higher than of photocatalysis mechanism. Both mechanisms obey pseudo-second order kinetics and the decomposition was identified from the shifted spectra of treated solution. Furthermore, the electrochemical sensing activity for the detection of heavy metal Hg ^2+ showed an increasing of sensitivity and feasibility of the SnO _2 /Au electrode compared to the bare Au with the limit of detection of 0.001 970 ppm. This result reveals the facile green synthesis route of SnO _2 NPs with the promising activities

Iridium oxide (IV) nanoparticle-based lateral flow immunoassay

Lateral flow biosensors are paper-based devices that allow the detection of different types of analytes with quickness, robustness and selectivity, without leaving behind paper sensors benefits as low-cost, recyclability and sustainability. Nanomaterials have been widely reported in lateral flow biosensors, offering new sensing strategies based on optical or electrical detection techniques. Looking for other advantageous nanomaterials, we propose for the first time the use of iridium oxide (IV) nanoparticles in lateral flow assays for the detection of human immunoglobulin as a model protein. These nanoparticles can be easily prepared and conjugated with biomarkers. Their dark blue color gives a high contrast against the white background of the strips being in this way excellent labels