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In this study, a novel electrochemical sensor for the accurate determination of ofloxacin in a pharmaceutical sample was developed using active-site-rich Cu2MoS4 nanoplates as an excellent electrocatalytic platform.

In this study, silver nanoparticles (AgNPs) were functionalized by various molecules, including sodium borohydride (NaBH4), polyhexamethylene biguanide hydrochloride (PHMB), and Tween 80 to investigate the long-term stabilization of AgNPs in an aqueous dispersion. PHMB-functionalized silver nanoparticles (AgNPs/PHMB) exhibited better stability than others and could be stored at ambient temperature for at least 180 days. In addition to creating stabilization based on the electrostatic repulsion, the use of PHMB helped to increase the degree of stability of the colloidal AgNPs for a long time owing to strong interactions between Ag atoms on AgNPs with nitrogen (N) positions in PHMB molecules. The formed bond led to improving maintenance ability of the electrostatic repulsion layer among independent nanoparticles. The applicability of the as-prepared AgNPs/PHMB was also examined for Mn2+ detection via a colorimetric approach. The calibration curve was found to be linear over the range of 0–100 mM with a correlation coefficient of 0.97. The amine groups of PHMB brought out a cooperative effect to form of ion-templated chelation with Mn2+, which caused the aggregation of AgNPs/PHMB. This suggested that the AgNPs/PHMB could be used as a potential probe in the detection of Mn2+ ions. More importantly, the long-term stability of AgNPs/PHMB paved a great promising path to provide many further solutions for the producer in practical applications.

The authors report the optical and electrical properties of nanocomposite films of Ag-nanowires (Ag-NWs) and indium-tin oxide nanoparticles (ITO-NPs) and their application in window electrodes in solar cells. We found that the electrical and optical properties of Ag-NWs/ITO-NPs nanocomposite films strongly depend on the thickness. Nanocomposite film with 1000 nm thickness was observed to be most suitable for application as window electrodes in Cu(Zn,Sn)(S,Se)2 solar cells. The parameters of the cell using a 1000 nm-thick nanocomposite window electrode are short-circuit current density of 24.2 mA/cm2, open-circuit voltage of 0.32 V, fill factor of 0.44, and conversion efficiency of 3.37%. The results demonstrated an economical pathway for fabricating solar cells without vacuum methods.

In this work, we investigated the effect of morphology on the analytical performance of α-Fe2O3 nanostructures-based electrochemical sensors toward chloramphenicol (CAP) antibiotic using three designed morphologies including α-Fe2O3 nano-tube (α-Fe2O3-T), α-Fe2O3 nano-rice (α-Fe2O3-R), and α-Fe2O3 nano-plate (α-Fe2O3-P). Among these morphologies, α-Fe2O3-T displayed an outstanding electrochemical activity owing to the unique hollow structure and large specific surface area. However, due to the small pores size, α-Fe2O3-T showed the high steric hindrance (SD) effect towards an antibiotic with complex molecular structure, as CAP, leading to a significant decrease of their CAP electrochemical sensing performance. The CAP analytical performance of α-Fe2O3-R was highest in investigated morphologies owing to a high density of exposed Fe3+ as well as less SD effect towards CAP molecules. Under optimized conditions, α-Fe2O3-R-based CAP electrochemical sensor reached an electrochemical sensitivity of 0.92 μA μM−1 cm−2 with a LOD of 0.11 μM in the detection range from 2.5–50 μM. In addition, all these α-Fe2O3 nanostructures-based electrochemical sensors had excellent stability and high anti-interference ability for CAP analysis in a complex food matrix, as shrimp sample. This study provides valuable insights into the morphology-dependent sensing properties of α-Fe2O3 nanostructures towards antibiotics, which is helpful to the design of novel α-Fe2O3-based electrochemical nanosensors.

In this study, carbon screen-printed electrodes (SPEs) modified with gold nanoparticles (AuNPs), were prepared for label-free detection of Escherichia coli(E. coli) O157. AuNPs were synthesized by an electrochemical method and then modified on the carbon SPEs to improve the stability and effectiveness of the biosensor. Anti-E. coli O157 antibody was immobilized on the modified SPEs via -NHS cross-linking. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were selected to investigate electrochemical properties of modified carbon SPEs in a 5.0 mM K3[Fe(CN)6]/ K4[Fe(CN)6] added with 0.1 M KCl as well as to detect E. coli O157 bacteria. Results showed that the carbon SPEs were successfully modified with AuNPs of 18.0 ± 1.6 nm. The electrochemical signal of modified SPEs was stable after CV cycles, and the charge transfer resistance (Rct) decreased approximately to half of its initial value. Importantly, electrochemical biosensors based on AuNPs-modified carbon SPEs could detect E. coli O157 in the range of 10–106 CFU/mL without labels. The limit of detection was found at 15 CFU/mL with a signal-to-noise ratio of 3:1, and the time of detection was about 30 min. The success of as-prepared biosensor could open a strategy of portable diagnostics for label-free and quick detection of bacterial pathogens causing food-borne diseases, hospital-acquired infections as well as the emerging and re-emerging infectious diseases.