An ultra-sensitive luteolin sensor based on Co-doped nitrogen-containing carbon framework/MoS2−MWCNTs composite for natural sample detection

As a common antioxidant and antimicrobial agent in plants, luteolin has a variety of pharmacological activities and biological effects, the ability to specifically bind proteins and thus inhibit novel coronaviruses and treat asthma. Here, Co doped nitrogen-containing carbon frameworks/MoS2−MWCNTs (Co@NCF/MoS2−MWCNTs) nanocomposites have been synthesized and successfully applied to electrochemical sensors. X-ray photoelectron spectroscopy, scanning electron microscopy and X-ray diffraction were used to examine the morphology and structure of the samples. Meanwhile, the electrochemical behavior of Co@NCF/MoS2−MWCNTs was investigated. Due to its excellent electrical conductivity, electrocatalytic activity and adsorption, it is used for the detection of luteolin. The Co@NCF/MoS2−MWCNTs/GCE sensor can detect luteolin in a linear range from 0.1 nM to 1.3 μM with a limit of detection of 0.071 nM. Satisfactory results were obtained for the detection of luteolin in natural samples. In addition, the redox mechanism and electrochemical reaction sites of luteolin were investigated by the scan rate of CV curves and density functional theory. This work demonstrates for the first time the combination of ZIF-67-derived Co@NCF and MoS2−MWCNTs as electrochemical sensors for the detection of luteolin, which opens a new window for the sensitive detection of luteolin. © 2022 Elsevier Ltd

Biopolymeric sustainable materials and their emerging applications

Advancements in polymer science and engineering have helped the scientific community to shift its attention towards the use of environmentally benign materials for reducing the environmental impact of conventional synthetic plastics. Biopolymers are environmentally benign, chemically versatile, sustainable, biocompatible, biodegradable, inherently functional, and ecofriendly materials that exhibit tremendous potential for a wide range of applications including food, electronics, agriculture, textile, biomedical, and cosmetics. This review also inspires the researchers toward more consumption of biopolymer-based composite materials as an alternative to synthetic composite materials. Herein, an overview of the latest knowledge of different natural- and synthetic-based biodegradable polymers and their fiber-reinforced composites is presented. The review discusses different degradation mechanisms of biopolymer-based composites as well as their sustainability aspects. This review also elucidates current challenges, future opportunities, and emerging applications of biopolymeric sustainable composites in numerous engineering fields. Finally, this review proposes biopolymeric sustainable materials as a propitious solution to the contemporary environmental crisis. © 2022 Elsevier Ltd.

State-of-the-art review of advanced electrospun nanofiber yarn-based textiles for biomedical applications.

The pandemic of the coronavirus disease 2019 (COVID-19) has made biotextiles, including face masks and protective clothing, quite familiar in our daily lives. Biotextiles are one broad category of textile products that are beyond our imagination. Currently, biotextiles have been routinely utilized in various biomedical fields, like daily protection, wound healing, tissue regeneration, drug delivery, and sensing, to improve the health and medical conditions of individuals. However, these biotextiles are commonly manufactured with fibers with diameters on the micrometer scale (> 10 µm). Recently, nanofibrous materials have aroused extensive attention in the fields of fiber science and textile engineering because the fibers with nanoscale diameters exhibited obviously superior performances, such as size and surface/interface effects as well as optical, electrical, mechanical, and biological properties, compared to microfibers. A combination of innovative electrospinning techniques and traditional textile-forming strategies opens a new window for the generation of nanofibrous biotextiles to renew and update traditional microfibrous biotextiles. In the last two decades, the conventional electrospinning device has been widely modified to generate nanofiber yarns (NYs) with the fiber diameters less than 1000 nm. The electrospun NYs can be further employed as the primary processing unit for manufacturing a new generation of nano-textiles using various textile-forming strategies. In this review, starting from the basic information of conventional electrospinning techniques, we summarize the innovative electrospinning strategies for NY fabrication and critically discuss their advantages and limitations. This review further covers the progress in the construction of electrospun NY-based nanotextiles and their recent applications in biomedical fields, mainly including surgical sutures, various scaffolds and implants for tissue engineering, smart wearable bioelectronics, and their current and potential applications in the COVID-19 pandemic. At the end, this review highlights and identifies the future needs and opportunities of electrospun NYs and NY-based nanotextiles for clinical use.

Highly Sensitive and Selective Sensing Probe for Determination of Anti-Covid-19 Remdesvir: Application to Pharmaceutical Dosage Form and Biological Fluids

We reported the first investigational electrochemical study for Remdesvir (REM). REM is a promising antiviral agent used recently for the treatment of the most dangerous pandemic disease nowadays (COVID-19). Anionic surfactant, silica nanoparticles, and multiwall carbon nanotubes modified carbon paste (SDS/SiO2/MWCNT/CPE) sensor was designed to introduce our approach. The results revealed irreversible diffusion oxidative reaction of REM with two well-defined peaks (E1/V = 1.19, E2/V = 1.35) in 0.1 M phosphate buffer of pH 6 using differential pulse (DP) voltammetry. A linear relationship between the peak current and the drug concentration was established over the concentration range of 1.66 × 10-7-3.52 × 10-6 M (100-200 ng ml-1) with a limit of detection (LOD) of 4.80 × 10-8 M and limit of quantitation (LOQ) of 8.0 × 10-8 M and mean % recovery ± % RSD of 99.05 ± 1.94. The proposed method succeeded in the determination of the drug in its pharmaceutical dosage form, in human plasma with and human urine samples. Finally, the method was validated according to ICH guidelines and FDA guidance for the determination of the drug in biological fluids. The developed data was found to be in good agreement with a validated reported method. © 2022 The Electrochemical Society ("ECS").

An Efficient Electrochemical Sandwich ELISA for Urinary Human Serum Albumin-Biomarker Based on Highly Redox-Active Thionine Surface-Confined MWCNT/PEDOT.PSS Platform

Human serum albumin (HSA) is an abundant protein in blood serum and an indicator of several illnesses, for instance, Covid-19, wherein, a severe decrement in the concentration level is noticed that leads to a higher risk of mortality. The conventional ELISA-based protocol has been referred for the analysis which is less sensitive, cumbersome and time-consuming (4-6 hours). Herein, we introduce, a new sandwich-type electrochemical immunosensor based on Thionine(Th)-redox immobilized f-MWCNT(f-carboxylic functionalized)+PEDOT.PSS modified glassy carbon/screen-printed electrode (GCE/f-MWCNT+PEDOT@Th) for quick (∼20 min), low-sample volume (1 µL) and low concentration (10-9 g/mL) analysis of HSA. The GCE/f-MWCNT+PEDOT@Th showed a highly stable and fouling-free surface-confined redox feature at an apparent standard electrode potential, Eo’=-0.25 V vs Ag/AgCl with a surface-excess value, ΓTh=14×10-9 mol cm-2. A sandwich-type electrochemical immunosensor was prepared by sequential immobilization of 1 µL respective solutions without any linking agent on the chemically modified electrode followed by incubation at 37°C for 3—5 min and testing its bioelectrocatalytic H2O2 (500 µM) reduction reaction in pH 7 PBS. Interrelated solution phased and experimental conditions were systematically optimized. Under an optimal working condition, the as-prepared bioelectrode, CME-Ab1p-SkM-HSA-Ab1m-Ab2HRP showed a reliable calibration plot of HSA in a concentration window, 10-9—10-4 g/mL. The obtained calibration plot was parallel to the ELISA of HSA in a limited concentration window, 10-7—10-4 g/mL. As a proof of concept, electrochemical immunosensing of urinary HSA has been demonstrated. Since, the new approach is simple, rapid, and efficient over conventional ELISA, it can be extendable to various HSA-real sample analyses.

Flexible, Highly Sensitive Paper-Based Screen Printed MWCNT/PDMS Composite Breath Sensor for Human Respiration Monitoring.

Accurate measurement and monitoring of respiration is vital in patients affected by severe acute respiratory syndrome coronavirus - 2 (SARS-CoV-2). Patients with severe chronic diseases and pneumonia need continuous respiration monitoring and oxygenation support. Existing respiratory sensing techniques require direct contact with the human body along with expensive and heavy Holter monitors for continuous real-time monitoring. In this work, we propose a low-cost, non-invasive and reliable paper-based wearable screen printed sensor for human respiration monitoring as an effective alternative of existing sensing systems. The proposed sensor was fabricated using traditional screen printing of multi-walled carbon nanotubes (MWCNTs) and polydimethylsiloxane (PDMS) composite based interdigitated electrodes on paper substrate. The paper substrate was used as humidity sensing material of the sensor. The hygroscopic nature of paper during inhalation and exhalation causes a change in dielectric constant, which in turn changes the capacitance of the sensor. The composite interdigitated electrode configuration exhibited better response times with a rise time of 1.178s being recorded during exhalation and fall time of 0.88s during inhalation periods. The respiration rate of sensor was successfully examined under various breathing conditions such as normal breathing, deep breathing, workout, oral breathing, nasal breathing, fast breathing and slow breathing by employing it in a wearable mask, a mandatory wearable product during the current COVID-19 pandemic situation.Thus, the above proposed sensor may hold tremendous potential in wearable/flexible healthcare technology with good sensitivity, stability, biodegradability and flexibility at this time of need.