Graphene field effect transistor biosensors based on aptamer for amyloid-β detection

The development of cost-efficient, sensitive and specific methods to detect amyloid-beta 42 ( Aβ42 ) biomarkers in cerebrospinal fluid and serum-samples is of considerable interest to enable early and reliable diagnosis of Alzheimer’s disease as a precondition for future disease-modifying therapies. This paper presents a reduced graphene oxide field effect transistor (r-GO FET) for label free ultrasensitive detection of an Aβ42 -biomarker with RNA aptamer. The channel in the device was formed by reduction of graphene oxide nanosheets by self-assembly process. As a result, the interaction between Aβ42 and RNA aptamer on the surface of r-GO channel caused a linear response in the shift of the gate voltage ( VTG ) where the minimum conductivity occurs. The r-GO FET can detect the biomarker in range of 1ng/ml to 1pg/ml at pH 7.4 with high specificity. The developed r-GO FET is a low-cost, highly sensitive and selective method for detecting tiny concentrations of Aβ42 , which would also enable measurements in serum-samples

Carbon based materials: a review of adsorbents for inorganic and organic compounds

This review presents the adsorptive removal process of hazardous materials onto carbon-based materials comprising activated carbon, graphene, carbon nanotubes, carbon nanofibers, biochar and carbon aerogels. Particular emphasis is placed on the fabrication of various carbon-based substances and their characteristics. As a ubiquitous phenomenon, dangerous compounds originating from industrial wastewater lead to damage to the environment and water resources. Therefore, among conventional technologies, adsorption is highly effective and the most extensively used method owing to its simplicity of performance and fairly low cost of application for the removal of hazardous pollutants. This paper comprehensively reviews a multitude of aspects regarding the chemical and physical nature of various carbon materials and their adsorption ability by increasing their surface area or their possible modification. Based on the properties of nano-carbon materials, adsorptive elimination mechanisms for antibiotics, dyes, heavy metals, pesticides, oils, phenolic and volatile organic compounds and gas pollutants are highlighted. The advantageous characteristics of nano-carbon materials assigned to their unique adsorptive removal of common hazardous substances will be pointed out

Recent progress in the design of photocatalytic H2O2 synthesis system

Photocatalytic synthesis of hydrogen peroxide under mild reaction conditions is a promising technology. This article will review the recent research progress in the design of photocatalytic H2O2 synthesis systems. A comprehensive discussion of the strategies that could solve two essential issues related to H2O2 synthesis. That is, how to improve the reaction kinetics of H2O2 formation via 2e− oxygen reduction reaction and inhibit the H2O2 decomposition through a variety of surface functionalization methods. The photocatalyst design and the reaction mechanism will be especially stressed in this work which will be concluded with an outlook to show the possible ways for synthesizing high-concentration H2O2 solution in the future

Wearable and flexible thin film thermoelectric module for multi-scale energy harvesting

Developing a thermoelectric generator(TEG) with shape conformable geometry for sustaining low-thermal impedance and large temperature gradient (ΔT) is fundamental for wearable and multi-scale energy harvesting applications. Here we demonstrate a flexible architectural design, with efficient thin film thermoelectric generator as a solution for this problem. This approach not only decreases the thermal impedance but also multiplies the temperature gradient, thereby increasing the power conversion efficiency (PCE) as comparable to bulk TEG. Intact thin films of Tin telluride (p-type) and Lead Telluride (n-type) are deposited on flexible substrate through physical vapor deposition and a thermoelectric module possessing a maximum output power density of 8.4 mW/cm2 is fabricated. We have demonstrated the performance of p-SnTe/n-PbTe based TEG as a flexible wearable power source for electronic gadgets, as a thermal touch sensor for real-time switching and temperature monitoring for exoskeleton applications

Low switching power neuromorphic perovskite devices with quick relearning functionality

In the quest to reduce energy consumption, there is a growing demand for technology beyond silicon as electronic materials for neuromorphic artificial intelligence devices. Equipped with the criteria of energy efficiency and excellent adaptability, organohalide perovskites can emulate the characteristics of synaptic functions in the human brain. In this aspect, this study designs and develops CsFAPbI3-based memristive neuromorphic devices that can switch at low power and show larger endurance by adopting the powder engineering methodology. The neuromorphic characteristics of the CsFAPbI3-based devices exhibit an ultra-high paired-pulse facilitation index for an applied electric stimuli pulse. Moreover, the transition from short-term to long-term memory requires ultra-low energy with long relaxation times. The learning and training cycles illustrate that the CsFAPbI3-based devices exhibit faster learning and memorization process owing to their larger carrier lifetime compared to other perovskites. The results provide a pathway to attain low-power neuromorphic devices that are synchronic to the human brain's performance

Highly Sensitive and Cost-Effective Portable Sensor for Early Gastric Carcinoma Diagnosis

Facile and efficient early detection of cancer is a major challenge in healthcare. Herein we developed a novel sensor made from a polycarbonate (PC) membrane with nanopores, followed by sequence-specific Oligo RNA modification for early gastric carcinoma diagnosis. In this design, the gastric cancer antigen CA72-4 is specifically conjugated to the Oligo RNA, thereby inhibiting the electrical current through the PC membrane in a concentration-dependent manner. The device can determine the concentration of cancer antigen CA72-4 in the range from 4 to 14 U/mL, possessing a sensitivity of 7.029 µAU−1mLcm−2 with a linear regression (R2) of 0.965 and a lower detection limit of 4 U/mL. This device has integrated advantages including high specificity and sensitivity and being simple, portable, and cost effective, which collectively enables a giant leap for cancer screening technologies towards clinical use. This is the first report to use RNA aptamers to detect CA72-4 for gastric carcinoma diagnosi

A β-cyclodextrin modified graphitic carbon nitride with Au co-catalyst for efficient photocatalytic hydrogen peroxide production

Photocatalytic hydrogen peroxide (H2O2) production has attracted considerable attention as a renewable and environment-friendly method to replace other traditional production techniques. The performance of H2O2 production remains limited by the inertness of graphitic carbon nitride (CN) towards the adsorption and activation of O2. In this work, a photocatalyst comprising of β-cyclodextrin (β-CD)-modified CN with supporting Au co-catalyst (Au/β-CD-CN) has been utilized for effective H2O2 production under visible light irradiation. The static contact angle measurement suggested that β-CD modification increased the hydrophobicity of the CN photocatalyst as well as its affinity to oxygen gas, leading to an increase in H2O2 production. The rate of H2O2 production reached more than 0.1 mM/h under visible-light irradiation. The electron spin resonance spectra indicated that H2O2 was directly formed via a 2-electron oxygen reduction reaction (ORR) over the Au/β-CD-CN photocatalyst

Gating a Single Cell:A Label-Free and Real-Time Measurement Method for Cellular Progression

There is an ever-growing need for more advanced methods to study the response of cancer cells to new therapies. To determine cancer cells’ response from a cell-mortality perspective to various cancer therapies, we report a label-free and real time method to monitor the in situ response of individual HeLa cells using a single cell gated transistor (SCGT). As a cell undergoes apoptotic cell death, it experiences changes in morphology and ion concentrations. This change is well in line with the threshold voltage of the SCGT, which has been verified by correlating the data with the cell morphologies by scanning electron microscopy and the ion-concentration analysis by inductively-coupled plasma mass spectrometry (ICPMS). This SCGT could replace patch clamps to study single cell activity via direct measurement in real time. Importantly, this SCGT can be used to study the electrical response of a single cell to stimuli that leaves the membrane intact

Fingertip‐skin‐inspired highly sensitive and multifunctional sensor with hierarchically structured conductive graphite/polydimethylsiloxane foams

Fingertip skin exhibits high sensitivity in a broad pressure range, and can detect diverse stimuli, including textures, temperature, humidity, etc. Despite adopting diverse microstructures and functional materials, achieving skin sensor devices possessing high pressure sensitivity over a wide linear range and with multifunctional sensing capabilities is still challenging. Herein, inspired by the microstructures of fingertip skin, a highly sensitive skin sensor is demonstrated with a linear response over a broad pressure range and multifunctional sensing capabilities. The porous sensing layer is designed with hierarchical microstructures on the surface. By optimizing the porosity and the graphite concentration, a fabricated skin sensor device exhibits a superior sensitivity of 245 kPa−1 over a broad linear pressure range from 5 Pa to 120 kPa. For practical application demonstrations, the sensor devices are utilized to monitor subtle wrist pulse and diverse human motions including finger bending, wrist bending, and feet movement. Furthermore, this novel sensor device demonstrates potential applications in recognizing textures and detecting environmental temperatures, thereby marking an important progress for constructing advanced electronic skin