Nitrogen-doped carbon dots: Recent developments in its fluorescent sensor applications.

Doped carbon dots have attracted great attention from researchers across disciplines because of their unique characteristics, such as their low toxicity, physiochemical stability, photostability, and outstanding biocompatibility. Nitrogen is one of the most commonly used elements for doping because of its sizeable atomic radius, strong electronegativity, abundance, and availability of electrons. This distinguishes them from other atoms and allows them to perform distinctive roles in various applications. Here, we have reviewed the most current breakthroughs in nitrogen-doped CDs (N-CDs) for fluorescent sensor applications in the last five years. The first section of the article addresses several synthetic and sustainable ways of making N-CDs. Next, we briefly reviewed the fluorescent features of N-CDs and their sensing mechanism. Furthermore, we have thoroughly reviewed their fluorescent sensor applications as sensors for cations, anions, small molecules, enzymes, antibiotics, pathogens, explosives, and pesticides. Finally, we have discussed the N-CDs' potential future as primary research and how that may be used. We hope that this study will contribute to a better understanding of the principles of N-CDs and the sensory applications that they can serve.

Genetically encoded light-up RNA aptamers and their applications for imaging and biosensing.

Intracellular small ligands and biomacromolecules are playing crucial roles not only as executors but also as regulators. It is essential to develop tools to investigate their dynamics to interrogate their functions and reflect the cellular status. Light-up RNA aptamers are RNA sequences that can bind with their cognate nonfluorescent fluorogens and greatly activate their fluorescence. The emergence of genetically encoded light-up RNA aptamers has provided fascinating tools for studying intracellular small ligands and biomacromolecules owing to their high fluorescence activation degree and facile programmability. Here we review the burgeoning field of light-up RNA aptamers. We first briefly introduce light-up RNA aptamers with a focus on the photophysical properties of the fluorogens. Then design strategies of genetically encoded light-up RNA aptamer based sensors including turn-on, signal amplification and ratiometric rationales are emphasized.

Nanomaterial-Enabled Wearable Sensors for Healthcare.

Highly sensitive wearable sensors that can be conformably attached to human skin or integrated with textiles to monitor the physiological parameters of human body or the surrounding environment have garnered tremendous interest. Owing to the large surface area and outstanding material properties, nanomaterials are promising building blocks for wearable sensors. Recent advances in the nanomaterial-enabled wearable sensors including temperature, electrophysiological, strain, tactile, electrochemical, and environmental sensors are presented in this review. Integration of multiple sensors for multimodal sensing and integration with other components into wearable systems are summarized. Representative applications of nanomaterial-enabled wearable sensors for healthcare, including continuous health monitoring, daily and sports activity tracking, and multifunctional electronic skin are highlighted. Finally, challenges, opportunities, and future perspectives in the field of nanomaterial-enabled wearable sensors are discussed.

Selective electrochemical recognition of the α-naphthol isomer and in situ immobilization of naphthoquinones for tunable electrocatalysis.

Fits like a glove: Separationless and selective electrochemical oxidation of the α-naphthol (α-NAP) isomer yields naphthoquinone species on the surface of multiwalled carbon nanotubes, which can further catalyze the electro-oxidation of NADH and hydrazine at different potentials. The ß-NAP isomer failed to show any such electro-oxidation.

Electrochemical-assisted encapsulation of catechol on a multiwalled carbon nanotube modified electrode.

Electrochemical-assisted encapsulation of a neurotransmitter, catechol (CA), as nanoaggregates on a multiwalled carbon nanotube (>90% of carbon basis MWNT) modified gold electrode (Au/CA@CNT) has been demonstrated without any derivatization or electrode preactivation procedures. Characterization of the CA@CNT by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared attenuated total reflection (FTIR/ATR) spectroscopy, and cyclic voltammetry (CV) collectively revealed stable encapsulation of the CA within strained and misalignment areas of the MWNT capsule. The Au/CA@CNT shows a couple of redox peaks centered at 0 (A1/C1) and 200 mV vs Ag/AgCl (A2/C2) due to the encapsulated (chemisorbed) and physisorbed CA moieties, respectively. The calculated chemisorbed catechol surface excess, Gamma(CA), value was 98.3 x 10(-10) mol x cm(-2). Control solution phase preparations of CA@CNTs yielded poor loading and instability problems, if it is chemically modified on the gold electrode. Electrochemical mediated oxidation of hydrazine on the Au/CA@CNT was demonstrated with an approximately 20 times increase in peak current and 200 mV reduction in the overpotential values in a pH 7 phosphate buffer solution.