Metal loaded nano-carbon gas sensor array for pollutant detection.

Many research works report a sensitive detection of a wide variety of gas species. However, their in-lab detection is usually performed by using single gases and, therefore, selectivity often remains an unsolved issue. This paper reports a four-sensor array employing different nano-carbon sensitive layers (bare graphene, SnO2@Graphene, WO3@Graphene, and Au@CNTs). The different gas-sensitive films were characterised via several techniques such as FESEM, TEM, and Raman. First, an extensive study was performed to detect isolated NO2, CO2, and NH3molecules, unravelling the sensing mechanism at the operating temperatures applied. Besides, the effect of the ambient moisture was also evaluated. Afterwards, a model for target gas identification and concentration prediction was developed. Indeed, the sensor array was used in mixtures of NO2and CO2for studying the cross-sensitivity and developing a calibration model. As a result, the NO2detection with different background levels of CO2was achieved with anR2of 0.987 and an RMSE of about 22 ppb.

Metal Oxide Nanoparticle-Decorated Few Layer Graphene Nanoflake Chemoresistors for the Detection of Aromatic Volatile Organic Compounds.

Benzene, toluene, and xylene, commonly known as BTX, are hazardous aromatic organic vapors with high toxicity towards living organisms. Many techniques are being developed to provide the community with portable, cost effective, and high performance BTX sensing devices in order to effectively monitor the quality of air. In this paper, we study the effect of decorating graphene with tin oxide (SnO2) or tungsten oxide (WO3) nanoparticles on its performance as a chemoresistive material for detecting BTX vapors. Transmission electron microscopy and environmental scanning electron microscopy are used as morphological characterization techniques. SnO2-decorated graphene displayed high sensitivity towards benzene, toluene, and xylene with the lowest tested concentrations of 2 ppm, 1.5 ppm, and 0.2 ppm, respectively. In addition, we found that, by employing these nanomaterials, the observed response could provide a unique double signal confirmation to identify the presence of benzene vapors for monitoring occupational exposure in the textiles, painting, and adhesives industries or in fuel stations.

Multiwalled carbon nanotube based aromatic volatile organic compound sensor: sensitivity enhancement through 1-hexadecanethiol functionalisation.

Aromatic volatile organic compound (VOC) sensors are attracting growing interest as a response to the pressing market need for sensitive, fast response, low power consumption and stable sensors. Benzene and toluene detection is subject to several potential applications such as air monitoring in chemical industries or even biosensing of human breath. In this work, we report the fabrication of a room temperature toluene and benzene sensor based on multiwall carbon nanotubes (MWCNTs) decorated with gold nanoparticles and functionalised with a long-chain thiol self-assembled monolayer, 1-hexadecanethiol (HDT). High-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) were performed to characterize the gold nanoparticle decoration and to examine the thiol monolayer bonding to the MWCNTs. The detection of aromatic vapours using Au-MWCNT and HDT/Au-MWCNT sensors down to the ppm range shows that the presence of the self-assembled layer increases the sensitivity (up to 17 times), selectivity and improves the response dynamics of the sensors.

A facile route to glycated albumin detection.

In this paper we propose an easy way to detect the glycated form of human serum albumin which is biomarker for several diseases such as diabetes and Alzheimer. The detection platform is a label free impedimetric immunosensor, in which we used a monoclonal human serum albumin antibody as a bioreceptor and electrochemical impedance as a transducing method. The antibody was deposited onto a gold surface by simple physisorption technique. Bovine serum albumin was used as a blocking agent for non-specific binding interactions. Cyclic voltammetry and electrochemical impedance spectroscopy were used for the characterization of each layer. Human serum albumin was glycated at different levels with several concentrations of glucose ranging from 0 mM to 500 mM representing physiological, pathological (diabetic albumin) and suprapathological concentration of glucose. Through the calibration curves, we could clearly distinguish between two different areas related to physiological and pathological albumin glycation levels. The immunosensor displayed a linear range from 7.49% to 15.79% of glycated albumin to total albumin with a good sensitivity. Surface plasmon resonance imaging was also used to characterize the developed immunosensor.

Electrochemical Impedance Spectroscopy on Interdigitated Gold Microelectrodes for Glycosylated Human Serum Albumin Characterization.

Glycosylated albumin is considered as a potentially accurate indicator of shorter-term average glucose concentration compared with the current standard HbA1c and as such, it is attracting the interest of the scientific community as a possible diagnosis marker for diabetic patients. The purpose of this paper is to achieve a better understanding of the glycation effect of albumin on its electrochemical properties. That is done through the use of Interdigitated gold microelectrodes (IDGE) as support in a label free impedimetric immunosensor for the detection of human serum albumin detection in glycated (GA) and non-glycated (HSA) form. Anti-human serum albumin, a monoclonal antibody, was physisorbed on the surface of IDGE and used as a HSA/GA bioreceptor. Electrochemical impedance spectroscopy, cyclic voltammetry, and surface plasmon resonance imaging (SPRi) were used for the characterization of the grafted layers onto the gold surface. A detection range from 1 to 401 ng/mL of non glycated HSA antigen in phosphate buffered saline buffer was obtained with the impedance spectroscopy technique. The experiment led to the observation of a significant impedance difference between the glycated and non-glycated antigen of HSA. SPRi measurements confirmed these findings and allowed us to suggest an increase of the dielectric permittivity for human serum albumin upon glycation.