Electrochemical Sensing Platform Based on Functionalized Multi-Walled Carbon Nanotubes and Metal Oxide for the Detection and Degradation Studies of Orange II Dye

Advances on carbon nanomaterials and their applications in medical diagnosis and drug delivery

Carbon nanomaterials are indispensable due to their unique properties of high electrical conductivity, mechanical strength and thermal stability, which makes them important nanomaterials in biomedical applications and waste management. Limitations of conventional nanomaterials, such as limited surface area, difficulty in fine tuning electrical or thermal properties and poor dispersibility, calls for the development of advanced nanomaterials to overcome such limitations. Commonly, carbon nanomaterials were synthesized by chemical vapor deposition (CVD), laser ablation or arc discharge methods. The advancement in these techniques yielded monodispersed carbon nanotubes (CNTs) and allows p-type and n-type doping to enhance its electrical and catalytic activities. The functionalized CNTs showed exceptional mechanical, electrical and thermal conductivity (3500-5000 W/mK) properties. On the other hand, carbon quantum dots (CQDs) exhibit strong photoluminescence properties with high quantum yield. Carbon nanohorns are another fascinating type of nanomaterial that exhibit a unique structure with high surface area and excellent adsorption properties. These carbon nanomaterials could improve waste management by adsorbing pollutants from water and soil, enabling precise environmental monitoring, while enhancing wastewater treatment and drug delivery systems. Herein, we have discussed the potentials of all these carbon nanomaterials in the context of innovative waste management solutions, fostering cleaner environments and healthier ecosystems for diverse biomedical applications such as biosensing, drug delivery, and environmental monitoring.

Surface-engineered natural fibers: Emerging alternative substrates for chemical sensor applications: A review

Natural fiber has become one of the most widely used alternative materials for chemical sensor fabrication due to its advantages, such as biocompatibility, flexibility, and self-microfluidic properties. Enhanced natural fiber surface has been used as a substrate in colorimetric and electrochemical sensors. This review focuses on improving the natural fiber properties for preparation as a substrate for chemical sensors. Various methods for natural fiber extraction are discussed and compared. Bleaching and decolorization is important for preparation of colorimetric sensors, while carbonization and nanoparticle doping are favorable for increasing their electrical conductivity for electrochemical sensor fabrication. Also, example fabrications and applications of natural fiber-based chemical sensors for chemical and biomarker detection are discussed. The selectivity of the sensors can be introduced and improved by surface modification of natural fiber, such as enzyme immobilization and biorecognition element functionalization, illustrating the adaptability of natural fiber as a smart sensing device, e.g., wearable and portable sensors. Ultimately, the high performances of natural fiber-based chemical sensors indicate the potential uses of natural fiber as a renewable and eco-friendly substrate material in the field of chemical sensors and biosensors for clinical diagnosis and environmental monitoring.

Recent trends and advancement in metal oxide nanoparticles for the degradation of dyes: synthesis, mechanism, types and its application

Synthetic dyes play a crucial role in our daily lives, especially in clothing, leather accessories, and furniture manufacturing. Unfortunately, these potentially carcinogenic substances are significantly impacting our water systems due to their widespread use. Dyes from various sources pose a serious environmental threat owing to their persistence and toxicity. Regulations underscore the urgency in addressing this problem. In response to this challenge, metal oxide nanoparticles such as titanium dioxide (TiO2), zinc oxide (ZnO), and iron oxide (Fe3O4) have emerged as intriguing options for dye degradation due to their unique characteristics and production methods. This paper aims to explore the types of nanoparticles suitable for dye degradation, various synthesis methods, and the properties of nanoparticles. The study elaborates on the photocatalytic and adsorption-desorption activities of metal oxide nanoparticles, elucidating their role in dye degradation and their application potential. Factors influencing degradation, including nanoparticle properties and environmental conditions, are discussed. Furthermore, the paper provides relevant case studies, practical applications in water treatment, and effluent treatment specifically in the textile sector. Challenges such as agglomeration, toxicity concerns, and cost-effectiveness are acknowledged. Future advancements in nanomaterial synthesis, their integration with other materials, and their impact on environmental regulations are potential areas for development. In conclusion, metal oxide nanoparticles possess immense potential in reducing dye pollution, and further research and development are essential to define their role in long-term environmental management.

Electrochemical detection and removal of brilliant blue dye via photocatalytic degradation and adsorption using phyto-synthesized nanoparticles

Herein, we report a sensitive electrochemical platform prepared by modifying the electrode surface with copper-doped zinc oxide nanoparticles; these nanoparticles were prepared via a green synthetic approach using the extract of Cassia fistula leaves and multiwalled carbon nanotubes (MWCNTs). For the best response of the electrode modifier, a number of experimental conditions were optimized to obtain the most intense signal of the target analyte Coomassie brilliant blue using a rapid analysis technique square wave voltammetry. The designed sensor displayed remarkable sensitivity for Coomassie brilliant blue with a detection limit of 0.1 nM under the optimized conditions. Moreover, the repeatability, specificity and reproducibility of the designed sensor demonstrated its potential for practical applications. The sensing platform was also used for monitoring the degradation kinetics of the Coomassie brilliant blue dye. Catalytic degradation of the dye was performed using the synergistic effect of Cu-ZnO NPs together with Fenton reagent. The dye degraded by 96% in 60 minutes under neutral conditions, which is one of the main achievements of this work that has never been reported. The photocatalytic breakdown of Coomassie brilliant blue was also monitored using UV-visible spectroscopy. The degradation kinetics results of both techniques agreed well. The adsorption of Coomassie brilliant blue using ZnO NPs was monitored spectrophotometrically. The adsorption data were fitted in a pseudo-second order kinetic model by following the Langmuir isotherm at lower concentration and Freundlich isotherm at higher concentration.

Photoelectrocatalytic Detection and Degradation Studies of a Hazardous Textile Dye Safranin T

Herein, we report an electrochemical scaffold consisting of functionalized multiwalled carbon nanotubes (COOH-fMWCNTs) and iron-doped zinc oxide nanoparticles (Fe-ZnO) for the detection of a hazardous textile dye safranin T (ST) and monitoring of its photocatalytic degradation. Prior to the detection and degradation analysis, Fe-ZnO NPs were synthesized by the sol-gel method and characterized by a number of structural and morphological techniques. The carboxyl moiety of COOH-fMWCNTs possessing a strong affinity for the amino functionality of ST led to significant enhancement of the current response at the designed electrochemical platform, whereas the electrocatalytic role, surface area enhancement, and the provision of binding sites of Fe-ZnO led to a further increase in the peak current intensity of ST. Electrochemical impedance spectroscopy showed that the sensing scaffold made of the glassy carbon electrode modified with COOH-fMWCNTs and Fe-ZnO efficiently transfers charge between the transducer and the redox probe. Under optimized conditions, the developed sensor showed a 2.3 nM limit of detection for ST. Moreover, recovery experiments and anti-interference tests qualified the sensing platform for practical applications. The dye was photocatalytically degraded using Fe-ZnO NPs up to 99% in 60 min with a rate constant of 0.068 min-1. The designed sensor was used to probe the degradation kinetics of the target dye, and the results were found consistent with the findings obtained from electronic absorption method. To the best of our knowledge, the present work is the first approach for the efficient detection and almost absolute degradation of ST.

Detection and Degradation Studies of Nile Blue Sulphate Using Electrochemical and UV-Vis Spectroscopic Techniques

An efficient and reliable electrochemical sensing platform based on COOH-fMWCNTs modified GCE (COOH-fMWCNTs/GCE) was designed for the detection of nanomolar concentration of Nile Blue Sulphate (NBS). In comparison to the bare GCE, the electrochemical sensing scaffold considerably enhanced the peak current response of NBS dye as confirmed from the results of voltammetric investigations. The electrochemical approach of detecting NBS in the droplet of its solution dried over the surface of modified electrode validated, the role of modifier in enhancing the sensing response. Under optimized conditions, the designed electrochemical platform demonstrated a wide linearity range (0.03–10 μM) for NBS, with LOD of 1.21 nM. Moreover, COOH-fMWCNTs/GCE was found reproducible and stable as confirmed by repeatability and inter-day durability tests. The selectivity of the designed sensing matrix was ensured by anti-interference tests. The photocatalytic degradation of NBS dye was carried out by using TiO2 nanoparticles as photocatalyst in the presence of H2O2. UV-visible spectroscopic studies revealed 95% photocatalytic degradation of NBS following a pseudo-first-order kinetics with a rate constant of 0.028 min−1. These findings were supported electrochemically by monitoring the photocatalytically degraded dye at the designed sensing platform. The color variation and final decolorization of the selected dye in water served as a visual indicator of the degradation process. To conclude, the designed sensing platform immobilized with COOH-fMWCNTs imparted improved selectivity and sensitivity to detect and to, monitor the photocatalytic degradation of NBS.