Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro) has been regarded as one of the ideal targets for the development of antiviral drugs. The currently used methods for the probing of Mpro activity and the screening of its inhibitors require the use of a double-labeled peptide substrate. In this work, we suggested that the label-free peptide substrate could induce the aggregation of AuNPs through the electrostatic interactions, and the cleavage of the peptide by the Mpro inhibited the aggregation of AuNPs. This fact allowed for the visual analysis of Mpro activity by observing the color change of the AuNPs suspension. Furthermore, the co-assembly of AuNPs and peptide was achieved on the peptide-covered electrode surface. Cleavage of the peptide substrate by the Mpro limited the formation of AuNPs/peptide assembles, thus allowing for the development of a simple and sensitive electrochemical method for Mpro detection in serum samples. The change of the electrochemical signal was easily monitored by electrochemical impedance spectroscopy (EIS). The detection limits of the colorimetric and electrochemical methods are 10 and 0.1 pM, respectively. This work should be valuable for the development of effective antiviral drugs and the design of novel optical and electrical biosensors.

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：In the present work, tin-sulfur based catalysts was prepared using Na 2 SO 3 and (CH 3 SO 3) 2 Sn and was tested in acetylene hydrochlorination. Based on the analysis of experiments results, the acetylene conversion of (CH 3 SO 3) 2 Sn/S@AC is still over 90% after 50 h reaction, at the reaction condition of T = 200 o C, V HCl /V C2H2 = 1.1:1.0 and C 2 H 2-GSHV = 15 h-1. According to the results of X-ray photoelectron spectroscopy (XPS), HCl adsorption experiments, and acetylene temperature programmed desorption (C 2 H 2-TPD), it is reasonable concluded that the interaction between Sn and S not only can retard the oxidation of Sn 2+ in catalysts but also strengthen the reactant adsorption capacity of tin-based catalysts. Furthermore, results obtained from nitrogen adsorption/desorption and XPS proved that the CH 3 SO 3-can effectively decrease the coke deposition of (CH 3 SO 3) 2 Sn/AC and thus prolong the lifetime of (CH 3 SO 3) 2 Sn/AC.

Exploring sustainable, low-cost and high-performance nonnoble metal (NNM) electrocatalysts as alternatives to Pt-based catalysts for oxygen reduction reaction (ORR) is crucial for the large-scale application of metal-air batteries and fuel cell technology. A new method for preparing ORR catalysts is to use biomass activated carbon supported transition metal. Biomass activated carbon has a highly porous structure which is beneficial to charge and energy transport. In this article, peanut shell activated carbon (PSAC) was prepared as a carrier and iron phthalocyanine (FePc) was the active component of the catalyst. Different mass ratios of the FePc and PSAC were selected for physical doping and then treated at a high temperature. The obtained catalyst FePc/PSAC-3/1 showed excellent ORR catalytic performance, the onset potential and the half-wave potential are 0.94 V and 0.85 V respectively, highly comparable to that of commercial Pt/C (20 wt% Pt) catalyst. FePc/PSAC-3/1 has good stability and better tolerance to the methanol crossover effect than the Pt/C catalyst in alkaline electrolytes. The product was further used as an air cathode to construct the Zn-air battery at the same time. The excellent recharge-ability was further evaluated by a 43 h longterm cycling test without noticeable deterioration for the voltage gap. This work demonstrates the great promise of developing new families of NNM ORR catalysts by the economical and sustainable process.

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