ABSTRACT
Electrochemical sensors consisting of screen-printed electrodes (SPEs) are recurrent devices in the recent literature for applications in different fields of interest and contribute to the expanding electroanalytical chemistry field. This is due to inherent characteristics that can be better (or only) achieved with the use of SPEs, including miniaturization, cost reduction, lower sample consumption, compatibility with portable equipment, and disposability. SPEs are also quite versatile; they can be manufactured using different formulations of conductive inks and substrates, and are of varied designs. Naturally, the analytical performance of SPEs is directly affected by the quality of the material used for printing and modifying the electrodes. In this sense, the most varied carbon nanomaterials have been explored for the preparation and modification of SPEs, providing devices with an enhanced electrochemical response and greater sensitivity, in addition to functionalized surfaces that can immobilize biological agents for the manufacture of biosensors. Considering the relevance and timeliness of the topic, this review aimed to provide an overview of the current scenario of the use of carbonaceous nanomaterials in the context of making electrochemical SPE sensors, from which different approaches will be presented, exploring materials traditionally investigated in electrochemistry, such as graphene, carbon nanotubes, carbon black, and those more recently investigated for this (carbon quantum dots, graphitic carbon nitride, and biochar). Perspectives on the use and expansion of these devices are also considered.
Subject(s)
Biosensing Techniques , Nanotubes, Carbon , Electrodes , Electrochemistry , Electrochemical TechniquesABSTRACT
With the prevalence of COVID-19, wearing medical surgical masks has become a requisite measure to protect against the invasion of the virus. Therefore, a huge amount of discarded medical surgical masks will be produced, which will become a potential hazard to pollute the environment and endanger the health of organisms without our awareness. Herein, a green and cost-effective way for the reasonable disposal of waste masks becomes necessary. In this work, we realized the transformation from waste medical surgical masks into high-quality carbon-nickel composite nanowires, which not only benefit the protection of the environment and ecosystem but also contribute to the realization of economic value. The obtained composite carbon-based materials demonstrate 70 S m-1 conductivity, 5.2 nm average pore diameters, 234 m2 g-1 surface areas, and proper graphitization degree. As an anode material for lithium-ion batteries, the prepared carbon composite materials demonstrate a specific capacity of 420 mA h g-1 after 800 cycles at a current density of 0.2 A g-1. It also displays good rate performance and decent cycling stability. Therefore, this study provides an approach to converting the discarded medical surgical masks into high-quality carbon nanowire anode materials to turn waste into treasure.
ABSTRACT
In this research, facile and highly reproducible route for fabrication of self-cleaning and self-disinfecting cellulose-based substrate enriched by exfoliated graphitic carbon nitride flakes deposited with silver nanoparticles (gCN_Ag) is reported. Cellulose-based sheets were studied in photocatalytic degradation of Rhodamine B (RhB) solutions with different concentartions depending the method: 5% or 25% solution, as well as in antibacterial and antiviral reduction of E. coli and S. aureus bacteria and Φ6 phage virus. Structure of Φ6 mimics COVID-19 viruses and is considered as a good research model for the current pandemic situation The effects of introducing gCN_Ag to the paper pulp on physicochemical, photocatalytic and microbiologic properties were approached. Two different methods of introducing paper sheets to RhB solution and bacterial/viral dispersions were presented: immersion sheets in medium and casting medium onto the sheets. In immersion method, our composite degraded 5% solution of RhB completely in 110 min and reduced E. coli and S. aureus bacteria and Φ6 phage virus in 2 h. According to standard describing contact method, the microbiological test took 24 h and resulted in 100 % reduction of the bacteria and virus viability as well. Photocatalytic process occurred on the solid substrate resulted in 90 % degradation of RhB in 110 min. Promising results indicate that paper based solid substrate is auspicious and scalable multifunctional material which can effectively work as self-cleaning and antimicrobial agent to improve the safety and cleanliness of our indoor space. Moreover, it can clean polluted water reservoirs. © 2022
ABSTRACT
Herein, a photoelectrochemical aptasensor for the quantitive measurement of the severe acute respiratory syndrome coronavirus-2 receptor-binding domain (Sars-Cov-2 RBD) has been reported for the first time. For this purpose, first, graphitic carbon nitride and (gC3N4) and cadmium sulfide (CdS) quantum dots were fabricated and characterized. After that, gC3N4 and CdS were mixed well. The fabricated nanomaterials were characterized by scanning transmission electron microscopy. Then, the CdS QDs-gC3N4 nanocomposite was added to the solution containing chitosan as an amine-rich polymer to generate a Chitosan/CdS-gC3N4 nanocomposite. Subsequently, the surface of the ITO electrode was modified with Chitosan/CdS-gC3N4. After that, the amine-terminal aptamer probes were immobilized on the surface of the Chitosan/CdS QDs-gC3N4/ITO electrode by using glutaraldehyde as an amine-amine crosslinker. The electrochemical performances of the electrodes were studied using cyclic voltammetry (CV), electrochemical Impedance Spectroscopy (EIS), and photo-electrochemistry (PEC). The surface coverage of the immobilized aptamer probe was founded to be 26.2 pmol.cm-2. The obtained results demonstrated that the proposed photo-electrochemical aptasensor can be used for the measurement of Sars-Cov-2 RBD within 0.5-32.0 nM. The limit of detection (LOD) was obtained to be 0.12 nM (at 3σ/slope). The affinity of the Aptamer/Chitosan/CdS QDs-gC3N4/ITO was also founded to be 3.4 nM by using Langmuir-typical adsorption systems. The proposed photo-electrochemical aptasensor was applied for the measurement of the spiked Sars-Cov-2 RBD in human saliva samples at two concentrations. The effect of the interfering biomaterials such as human immunoglobulin G human immunoglobulin A, human immunoglobulin M, and human serum albumin was also studied.