Advanced Oxidation Processes of Amoxicillin Based on Visible Light Active Nitrogen-Doped TiO2 Photocatalyst

Environmental consequences during the COVID-19 pandemic have attracted attention due to the excessive use of antibiotics which lead to the release of the drug's residue, such as amoxicillin (AMX), into the environment. In this work, an advanced oxidation process based on a visible, active N-doped TiO2 photocatalyst was carried out to eliminate AMX. Nitrogen with different initial doping concentrations (15, 30, 45% w/w) was doped into TiO2 by the sol-gel method. The characterization technique such as XRD, FTIR, UV-SRS, and SEM-EDX revealed that nitrogen with 30% doping concentration improved the TiO2 response in the visible region, attributed to the lower band gap energy (2.97 eV). In the photodegradation processes, the TiO2-N (30%) photocatalyst possessed higher AMX degradation than undoped TiO2 for both UV and visible light irradiation. In an aqueous solution, the degradation percentage of AMX by TiO2-N (30%) was 68.5 and 84.12%, while the degradation percentage of AMX by TiO2 was 38.7 and 78.01% under visible and UV light, respectively. © Kusuma Putri Suwondo et al.

Label-free electrochemical immunosensor for highly sensitive COVID-19 spike protein detection.

The ongoing coronavirus pandemic responsible for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly increased the rate of global death and infections due to variant mutations (such as Delta and Omicron). While specifically developed and approved vaccines can limit the spread of disease in a population and severity of resulting symptoms, none have been demonstrated to effectively prevent infection altogether. Thus, reliable early diagnosis of COVID-19 is critical to identify positive cases to help contain the outbreak. Herein we report a label-free electrochemical immunosensor for rapid diagnosis of COVID-19 by using nitrogen-doped holey graphene (N-HRGO) as a nanocarrier decorated with thionine (TH) molecules as electrochemical indicators. With the spike protein located on the surface of the COVID-19 particles as the model target, the as-prepared electrochemical immunosensor could detect the presence of the COVID-19 spike protein over a wide linear range (1 pg mL-1-10 ng mL-1) with a low detection limit (0.3 pg mL-1). In addition, the developed electrochemical immunosensor exhibited an excellent selectivity (with insignificant current changes towards interfering proteins comparing with COVID-19 spike protein), a good reproducibility and long-term storage stability. Importantly, the electrochemical immunosensor thus developed could successfully and reliably detect the spike protein of COVID-19 in saliva and human serum complex samples. Thus, the as-prepared label-free electrochemical immunosensor can achieve rapid and sensitive detection of the COVID-19 spike protein, as a promising clinical diagnosis tool in monitoring the progression of COVID-19.

N-Doped Carbon Quantum Dots for Differential Detection of Doxycycline in Pharmaceutical Sewage and in Bacterial Cell

For the past two years, doxycycline has been employed hugely for the treatment of COVID 19 over the globe. Excessive use of doxycycline can result in bacteria and gene resistance, which affects the future treatment of infectious diseases. Furthermore, unused doxycycline left from the hospital and pharmaceutical industries may have an adverse effect on the environment, posing a significant menace to modern society. As a result, doxycycline detection is required. Herein, we developed blue luminous nitrogen-doped carbon quantum dots (N-CQDs) using ascorbic acid and diethylenetriamine (DETA) as carbon and nitrogen sources via a microwave-assisted technique for the differential detection of doxycycline (DC) via a fluorescence quenching mechanism, even when other tetracycline derivatives interfere. The quenching mechanism has been elaborately explained by using a Stern-Volmer plot, UV-vis and fluorescence spectroscopy, and TCSPC to attribute the static quenching and inner filter effect. In addition, the limit of detection of our suggested sensor is 0.25 μM. To confirm the structural properties and the size of the N-CQDs, FT-IR, Raman spectroscopy, HRTEM, DLS, and EDX have been performed. Moreover, this approach was used to identify doxycycline in pharmaceutical waste and bacterial cells. Because of its great sensitivity and selectivity, N-CQDs are ideal for measuring DC in environmental applications. © 2022 American Chemical Society. All rights reserved.

Hydrophobic RuO2/Graphene/N-doped porous carbon hybrid catalyst for Li-air batteries operating in ambient air

Li–air batteries have received significant attention for their ultrahigh theoretical energy density. However, the byproducts induced by attacking air hinder the conversion of Li–O2 batteries to Li–air batteries. Humidity is one of the main obstacles, not only causing side reactions with the discharge products but also leading to rapid corrosion of the lithium anode. Here, we fabricated a novel composite hydrophobic catalyst by loading RuO2 and graphene on N-doped porous carbon. The catalyst was endowed with hydrophobicity and showed superior catalytic performance and low affinity to water in the air. A Li–air battery equipped with this novel composite catalyst exhibited eminent cycling performance in pure oxygen (over 470 h), humid oxygen [∼40% relative humidity (RH), over 310 h], and ambient air (∼42% RH, over 330 h) at a current density of 500 mA g−1, and the discharge specific capacity increased from 13122.1 to 19358.6 mAh g−1. © 2022