Europium oxide nanorod-reduced graphene oxide nanocomposites towards supercapacitors

Europium oxide modified reduced graphene oxide composite for trace detection of hydrogen phosphate ions in soil samples

The phosphate (PO43-) ion is a constituent of the environment, soil, plants, and animals. There should be a real-time and portable phosphate detection sensor. Herein we propose a colorimetry based sensitive method for hydrogen phosphate (HPO42-) ions detection using europium oxide modified reduced graphene oxide composite (Eu2O3-RGO) and gold nanoparticles (Au NPs). We detect the HPO42- by observing the anti-aggregation of gold nanoparticles. In the presence of a Eu2O3-RGO composite, the Au NPs underwent an aggregation process, causing a colour change of Au NPs from wine red to wine blue. Once Eu-modified RGO was pre-mixed with HPO42- ions and introduced into Au NPs, the Eu nanoparticles in the Eu-modified RGO were attracted to the HPO42- ions. Because of this, the aggregated Au NPs started to anti-aggregate, and the colour of Au NPs changed from wine blue to wine red. The calibration curve of the sensor goes from 0 nM to 500 nM concentration of HPO42- ions. Our sensor has a detection limit of 0.08 nM, which is lower than the reported values. This improved lower detection limit is probably due to the use of RGO, which according to the literature review, can adsorb phosphate ions onto its surface. We optimized the incubation time and europium oxide (Eu2O3) nanoparticle concentration to improve the sensor's sensitivity. Lastly, we tested an agricultural sample using our developed method.

Designing 3D Ternary Hybrid Composites Composed of Graphene, Biochar and Manganese Dioxide as High-Performance Supercapacitor Electrodes

Biochar derived from waste biomass has proven to be an encouraging novel electrode material in supercapacitors. In this work, luffa sponge-derived activated carbon with a special structure is produced through carbonization and KOH activation. The reduced graphene oxide (rGO) and manganese dioxide (MnO₂) are in-situ synthesized on luffa-activated carbon (LAC) to improve the supercapacitive behavior. The structure and morphology of LAC, LAC-rGO and LAC-rGO-MnO₂ are characterized by the employment of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), BET analysis, Raman spectroscopy and scanning electron microscopy (SEM). The electrochemical performance of electrodes is performed in two and three-electrode systems. In the asymmetrical two-electrode system, the LAC-rGO-MnO₂//Co₃O₄-rGO device shows high specific capacitance (SC), high-rate capability and excellent cycle reversibly in a wide potential window of 0-1.8 V. The maximum specific capacitance (SC) of the asymmetric device is 586 F g^-1 at a scan rate of 2 mV s^-1. More importantly, the LAC-rGO-MnO₂//Co₃O₄-rGO device exhibits a specific energy of 31.4 W h kg^-1 at a specific power of 400 W kg^-1. Overall, the synergistic effect between the ternary structures of microporous LAC, rGO sheets and MnO₂ nanoparticles leads to the introduction of high-performance hierarchical supercapacitor electrodes.

Synthesis, chemical and biochemical characterization of Lu2O3-iPSMA nanoparticles activated by neutron irradiation

Among the nanomaterials, rare sesquioxides (lanthanide oxides such as Lu₂O₃) are of interest due to their adequate thermal conductivity, excellent chemical stability, and high light output. The prostate-specific membrane antigen (PSMA) is an integral multifunctional protein overexpressed in various types of cancer cells. The radiolabeled PSMA inhibitor peptides (iPSMA) have demonstrated their usefulness as specific probes in the treatment and detection of a wide variety of neoplasms, mainly due to their high in vivo recognition by the PSMA protein. The objective of this research was to synthesize Lu₂O₃-iPSMA nanoparticles (NPs) and characterize their physicochemical properties before and after neutron activation, as well as to assess their biodistribution profile and in vitro potential to target cells overexpressing PSMA. The Lu₂O₃ NPs were synthesized by the precipitation-calcination method and conjugated to the iPSMA peptide using DOTA (1,4,7,10-tetraazocyclodecane-N,N',N″,N‴-tetraacetic acid) as a linking agent. Results of the physicochemical characterization by FT-IR and UV-Vis spectroscopies, SEM, TEM, DLS, HRTEM, SAED, DSC-TGA, and X-ray diffraction indicated the formation of Lu₂O₃-iPSMA NPs (diameter of 29.98 ± 9.07 nm), which were not affected in their physicochemical properties after neutron activation. ¹⁷⁷Lu₂O₃-iPSMA NPs showed high affinity (K_d = 5.7 ± 1.9 nM) for the PSMA protein, evaluated by the saturation assay on HepG2 hepatocellular carcinoma cells (PSMA-positive). The biodistribution profile of the nanosystem in healthy mice showed the main uptake in the liver. After irradiation, radioactive Lu₂O₃-iPSMA NPs exhibited radioluminescent properties, making the in vivo acquisition of their biodistribution, via optical imaging, possible. The results obtained from this research validate the execution of additional preclinical studies with the objective of evaluating the potential of the ¹⁷⁷Lu₂O₃-iPSMA NPs for the targeted radiotherapy and in vivo imaging of tumors overexpressing the PSMA protein.

Terbium metal–organic frameworks as capable electrodes for supercapacitors

Tb-MOF as electrode material for supercapacitors with high specific capacitance and excellent capacitance retention.