Synthesis, characterization and electrochemical evaluation of a novel high performance GO-Fc/PANI nanocomposite for supercapacitor applications

Competitive electrochemical aptasensor for high sensitivity detection of liver cancer marker GP73 based on rGO-Fc-PANi nanocomposites

Golgi protein 73 (GP73) is a novel tumor marker in the early diagnosis and prognosis of hepatocellular carcinoma (HCC). Herein, a competitive electrochemical aptasensor for detecting GP73 was constructed using reduced graphene oxide-ferrocene-polyaniline nanocomposite (rGO-Fc-PANi) as the biosensing platform. The rGO-Fc-PANi had larger specific surface area, excellent conductivity and outstanding electroactive performance, which served as nanocarrier for GP73 aptamer (GP73Apt) binding and as redox nanoprobe for record electrical signal. Then, a complementary chain (cDNA) was fixed to the electrode by hybridization with GP73Apt. When GP73 was present, a competitive process happened among cDNA, GP73Apt and GP73, formed the GP73-GP73Apt stable chemical structure and made cDNA detach from the sensing electrode, resulting in enhancement of electrical signal. The difference in the corresponding peak current before and after the competition can be used to indicate the quantitative of GP73. Under optimal conditions, the DPV current response showed a good log-linear relationship with GP73 concentrations (0.001 ∼ 100.0 ng/mL) with a detection limit of 0.15 pg/mL (S/N = 3). It was successfully used for GP73 detection in human serum with RSDs ranging from 1.08 % to 6.96 %. Therefore, the aptasensor could provide an innovative technology platform and hold a great potential in clinical application.

Green Synthesis of Metal Nanoparticles with Borojó (Borojoa patinoi) Extracts and Their Application in As Removal in Water Matrix

The predominant aim of the current research was to generate a proposal for the removal of arsenic, a highly toxic pollutant, encountered within the Papallacta Lagoon in Ecuador. The average concentrations of As yielded ranges between 18 to 652 μg/L, through the use of metallic nanoparticles. Sampling was performed in the lagoon with their respective geographic locations and "in situ" parameters. Nanoparticles of Mn3O4 NPs, Fe3O4 NPs, and CuO NPs were synthesized at a 0.5 M concentration, using the precipitation method, and borojó (Borojoa patinoi) extract was added as an anti-caking agent as well as antioxidant. The nanoparticles were characterized by visible spectrophotometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy. After arsenic removal treatment using nanoparticles, a randomized experimental design of different concentrations (5 mg/L, 10 mg/L, 25 mg/L, 50 mg/L, 100 mg/L, and 150 mg/L) was applied at laboratory level. The average diameter of Fe3O4NPs ranged from 9 nm to 36 nm, Mn3O4 NPs were 15-20 nm, and CuO NPs ranged from 25 nm to 30 nm. Arsenic removal percentages using Fe3O4 NPs with a concentration of 150 mg/L was 87%; with Mn3O4 NPs, the removal was 70% and CuO NPs of about 63.5%. Finally, these nanoparticles could be used in a water treatment plant for the Papallacta Lagoon.

Gamma radiation assisted green synthesis of hesperidin-reduced graphene oxide nanocomposite targeted JNK/SMAD4/MMP2 signaling pathway

In this study, a novel method for the fabrication of hesperidin/reduced graphene oxide nanocomposite (RGOH) with the assistance of gamma rays is reported. The different RGOHs were obtained by varying hesperidin concentrations (25, 50, 100, and 200 wt.%) in graphene oxide (GO) solution. Hesperidin concentrations (25, 50, 100, and 200 wt.%) in graphene oxide (GO) were varied to produce the various RGOHs. Upon irradiation with 80 kGy from γ-Ray, the successful reduction of GO occurred in the presence of hesperidin. The reduction process was confirmed by different characterization techniques such as FTIR, XRD, HRTEM, and Raman Spectroscopy. A cytotoxicity study using the MTT method was performed to evaluate the cytotoxic-anticancer effects of arbitrary RGOH on Wi38, CaCo2, and HepG2 cell lines. The assessment of RGOH's anti-inflammatory activity, including the monitoring of IL-1B and IL-6 activities as well as NF-kB gene expression was done. In addition, the anti-invasive and antimetastatic properties of RGOH, ICAM, and VCAM were assessed. Additionally, the expression of the MMP2-9 gene was quantified. The assessment of apoptotic activity was conducted by the detection of gene expressions related to BCl2 and P53. The documentation of the JNK/SMAD4/MMP2 signaling pathway was ultimately accomplished. The findings of our study indicate that RGOH therapy has significant inhibitory effects on the JNK/SMAD4/MMP2 pathway. This suggests that it could be a potential therapeutic option for cancer.

Facial preparation of covalent modified reduced graphene oxide/polyaniline composite and its stable-enhanced electrochemical performance

Graphene-polyaniline composites have captured extensive attention because of their outstanding performance during the electrochemical process, while their practical applications are limited due to the complex and uncontrollable preparation process. This work provides a simple and controllable preparation route, in which covalent modified reduced graphene oxide (E-RGO) is successfully prepared by ethylenediamine (EDA) and graphene oxide (GO), and E-RGO with different degrees of modification is obtained by adjusting the amount of EDA during the preparation process, and then in situ polymerization of aniline monomer is used to produce E-RGO/PANI in E-RGO suspension. Among them, E-RGO-12 has a relatively stretched sheet, which provides a large support surface for the subsequent in-situ polymerization of aniline and increases the utilization rate of graphene. The PANI network is tightly wrapped on the surface of E-RGO, forming a "PANI-(E-RGO)-PANI" lamellar structure and the single components are connected by covalent bonds and have a strong conjugation effect. The rough surface of the E-RGO/PANI composite and the pores in the PANI network are conducive for the electrochemical process, which increases the active site of electrode reaction, and thus improve the electron transfer rate. E-RGO-12/PANI exhibits superior property with the specific capacitance of 398 F/g at 0.6 A/g, and after the current density changes to 6 A/g, the specific capacitance retention rate is 64.8%. After 2000 cycles, the capacitance retention rate is 76.4%. The current work provides a green and efficient new idea for reducing graphene oxide and preparing E-RGO/PANI composite materials for the energy storage device.

Smart-Fabric-Based Supercapacitor with Long-Term Durability and Waterproof Properties toward Wearable Applications

The rapid development of wearable electronics and smart textiles has dramatically motivated the generation of flexible textile-based supercapacitors (SCs). However, the rapid evaporation of water moisture in gel electrolyte substantially limits the working durability and performance enhancements of the flexible devices. Therefore, a high-performance multifunctional textile-based SC with long-term durability is highly desired. Herein, a poly(vinyl alcohol) (PVA)/polyacrylamide (PAM) composite gel electrolyte was developed to fabricate multifunctional device with water-retaining and water-proofing properties based on multidimensional hierarchical fabric. And the assembled SC based on composite gel exhibited a superior water-retaining property and long-term working durability (93.29% retention rate after operation for 15 days), whereas the performance of SC based on pure PVA gel declined sharply and only 43.2% capacitance remained. In addition, the assembled SC exhibited enhanced specific capacitance of 707.9 mF/cm² and high energy density of 62.92 μWh/cm² and maintained a good stability of 80.8% even after 10 000 cyclic tests. After water repellency treatment, the integrated device immersed in water could still work normally. What's more, the assembled devices could be charged by a portable hand generator, which could be potentially applied for field rescue and military applications. We foresee that this strategy would be a potential route to prepare high-performance multifunctional textile-based SCs for wearable electronic systems and smart textile applications.

Electrochemical Applications of Ferrocene-Based Coordination Polymers

Ferrocene and its derivatives, especially ferrocene-based coordination polymers (Fc-CPs), offer the benefits of high thermal stability, two stable redox states, fast electron transfer, and excellent charge/discharge efficiency, thus holding great promise for electrochemical applications. Herein, we describe the synthesis and electrochemical applications of Fc-CPs and reveal how the incorporation of ferrocene units into coordination polymers containing other metals results in unprecedented properties. Moreover, we discuss the usage of Fc-CPs in supercapacitors, batteries, and sensors as well as further applications of these polymers, for example in electrocatalysts, water purification systems, adsorption/storage systems.

Composites and Copolymers Containing Redox-Active Molecules and Intrinsically Conducting Polymers as Active Masses for Supercapacitor Electrodes—An Introduction

In this introductory report, composites and copolymers combining intrinsically conducting polymers and redox-active organic molecules, suggested as active masses without additional binder and conducting agents for supercapacitor electrodes, possibly using the advantageous properties of both constituents, are presented. A brief overview of the few reported examples of the use of such copolymers, composites, and comparable combinations of organic molecules and carbon supports is given. For comparison a few related reports on similar materials without intrinsically conducting polymers are included.