Green synthesis of starch-capped Cu2O nanocubes and their application in the direct electrochemical detection of glucose

Solanum tuberosum tuber-driven starch-mediated green-hydrothermal synthesis of cerium oxide nanoparticles for efficient photocatalysis and antimicrobial activities

In this study, we are reporting for the first time the utilization of Solanum tuberosum tuber-driven, starch-mediated, green-hydrothermally synthesized cerium oxide nanoparticles (G-CeO2 NPs) for the antibacterial activity and photodegradation of cationic (methylene blue, MB) and anionic (methyl orange, MO) dyes separately and in combination, aimed at environmental remediation. The XRD analysis confirms the fluorite structure of G-CeO2 NPs, displaying an average crystallite size of 9.6 nm. Further, XPS confirms the existence of 24% of Ce3+ oxidation states within G-CeO2 NPs. Morphological studies through FE-SEM and TEM reveal that starch-driven OH- ion production leads to a high percentage of active crystal facets, favoring the formation of Ce3+-rich CeO2 NPs. Photocatalytic experiments conducted under UV-A illumination demonstrate the superior degradation performance of G-CeO2 NPs, with MB degradation reaching 93.4% and MO degradation at 77.2% within 90 min. This outstanding catalytic activity is attributed to the mesoporous structure (pore diameter of 5.63 nm) with a narrow band gap, a large surface area (103.38 m2g-1), and reduced charge recombination, as validated by BET, UV-visible, and electrochemical investigations. The identification of photogenerated intermediates is achieved through LCMS, while the mineralization is monitored via total organic carbon analysis. Moreover, the scavenging experiments point towards the involvement of reactive oxygen species in organic oxidation, demonstrating efficiency over five consecutive trials. Additionally, G-CeO2 NPs exhibit potent antibacterial activity against both gram-positive and gram-negative bacteria. This study presents an innovative, and efficient approach to environmental remediation, shedding light on the potential of G-CeO2 NPs in addressing environmental pollution challenges.

One-step hydrothermal synthesis of CuS/MoS2 composite for use as an electrochemical non-enzymatic glucose sensor

Early diagnosis may be crucial for the prevention of chronic diabetes mellitus. For that herein, we prepared a CuS/MoS2 composite for a non-enzymatic glucose sensor through a one-step hydrothermal method owing to the synergetic effect of CuS/MoS2. The surface morphology of CuS/MoS2 was studied by Field Emission Scanning Electron Microscopy (FESEM) and Cs-corrected Scanning Transmission Electron Microscopy (Cs-STEM). The crystallinity and surface composition of CuS/MoS2 were analyzed by X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) respectively. The working electrode was prepared from CuS/MoS2 electrocatalyst, and for that dispersed solution of electrocatalyst was used to fabricate the material-loaded glassy carbon electrode (GC). CuS/MoS2 composite shows the viability of electrocatalyst to oxidize glucose in an alkaline solution with sensitivity and detection limit of 252.71 μA mM-1 cm-2 and 1.52 μM respectively. The proposed glucose sensor showed reasonable stability and potential selectivity during electrochemical analysis. Accordingly, the CuS/MoS2 composite has potential as a viable material for glucose sensing in diluted human serum.

Nanostructured Titanium Dioxide Surfaces for Electrochemical Biosensing

TiO2 electrochemical biosensors represent an option for biomolecules recognition associated with diseases, food or environmental contaminants, drug interactions and related topics. The relevance of TiO2 biosensors is due to the high selectivity and sensitivity that can be achieved. The development of electrochemical biosensors based on nanostructured TiO2 surfaces requires knowing the signal extracted from them and its relationship with the properties of the transducer, such as the crystalline phase, the roughness and the morphology of the TiO2 nanostructures. Using relevant literature published in the last decade, an overview of TiO2 based biosensors is here provided. First, the principal fabrication methods of nanostructured TiO2 surfaces are presented and their properties are briefly described. Secondly, the different detection techniques and representative examples of their applications are provided. Finally, the functionalization strategies with biomolecules are discussed. This work could contribute as a reference for the design of electrochemical biosensors based on nanostructured TiO2 surfaces, considering the detection technique and the experimental electrochemical conditions needed for a specific analyte.