Recent interest in flexible electronics and wearable devices has created a demand for fast and highly repeatable printing processes suitable for device manufacturing. Robust printing technology is critical for the integration of sensors and other devices on flexible substrates such as paper and textile. An atmospheric pressure plasma-based printing process has been developed to deposit different types of nanomaterials on flexible substrates. Multiwalled carbon nanotubes were deposited on paper to demonstrate site-selective deposition as well as direct printing without any type of patterning. Plasma-printed nanotubes were compared with non-plasma-printed samples under similar gas flow and other experimental conditions and found to be denser with higher conductivity. The utility of the nanotubes on the paper substrate as a biosensor and chemical sensor was demonstrated by the detection of dopamine, a neurotransmitter, and ammonia, respectively.

In the last decade, researchers have been searching for innovative platforms, methods, and techniques able to address recurring problems with the current cancer detection methods. Early disease detection, fast results, point-of-care sensing, and cost are among the most prevalent issues that need further exploration in this field. Herein, studies are focused on overcoming these problems by developing an electrochemical device able to detect telomerase as a cancer biomarker. Electrochemical platforms and techniques are more appealing for cancer detection, offering lower costs than the established cancer detection methods, high sensitivity inherent to the technique, rapid signal processing, and their capacity of being miniaturized. Therefore, Au interdigital electrodes and electrochemical impedance spectroscopy were used to detect telomerase activity in acute T cell leukemia. Different cancer cell concentrations were evaluated, and a detection limit of 1.9 × 105 cells/mL was obtained. X-ray photoelectron spectroscopy was used to characterize the telomerase substrate (TS) DNA probe self-assembled monolayer on gold electrode surfaces. Atomic force microscopy displayed three-dimensional images of the surface to establish a height difference of 9.0 nm between the bare electrode and TS-modified Au electrodes. The TS probe is rich in guanines, thus forming secondary structures known as G-quadruplex that can be triggered with a fluorescence probe. Confocal microscopy fluorescence images showed the formation of DNA G-quadruplex because of TS elongation by telomerase on the Au electrode surface. Moreover, electrodes exposed to telomerase containing 2′,3′-dideoxyguanosine-5′-triphosphate (ddGTP) did not exhibit high fluorescence, as ddGTP is a telomerase inhibitor, thus making this device suitable for telomerase inhibitors capacity studies. The electrochemical method and Au microchip device may be developed as a biosensor for a point-of-care medical device.

In the last decade, a great amount of effort has gone into developing methods and devices that detect early signs of cancer diseases fast and with high efficiency. Telomerase based biosensors are an attractive alternative that comply with this requirements. Telomerase serves as a cancer biomarker because it is present in the vast majority of cancers. This enzyme elongates telomeres at the end of the chromosomal DNA, which causes cancer cells to become immortal. In this work, we developed a modified inter-digitated array gold microelectrode as the sensing platform with Electrochemical Impedance Spectroscopy (EIS) as the measuring technique for the telomerase activity. The resulting DNA biosensor detects telomerase activity in total protein extracts from Jurkat T-acute lymphoblastic leukemia cells. This simple system is a good proof of concept for a fast and efficient method that can detect telomerase activity in cancer cells.

Ram P. (2017). Efficacy of atmospheric pressure dielectric barrier discharge for inactivating airborne pathogens. Journal of Vacuum Science and Technology A: Vacuum, Surfaces, and Films, 35(4) 041101. For guidance on citations see FAQs.