Carbon dots are admirable fluorescent nanomaterials due to their low cost, high photostability, excellent biocompatibility, and environmental friendliness. Most conventional carbon dot fabrication approaches produce single-colored fluorescent material in the preparation process; different methods are therefore required to synthesize distinct carbon dots for specific optical applications. In this study, carbon dots carrying different emission colors are prepared through a one-step refluxing process. The emission of these materials can be well-tuned by sodium hydroxide content in the precursor solution. The carbon dots produced are used as sensing probes based on the spectrofluorometric inner filter effect for target molecule detection. Three sensing categories that combine carbon dots and inner filter effect are demonstrated, including direct, metal nanoparticle-assisted, and enzymatic reaction-supported detection. Caffeine, melamine, and fenitrothion are selected as targets to demonstrate the strategies, respectively. These multifunctional carbon dot-based sensors achieve comparable sensitivity toward analytes with a much more convenient preparation route.
Flexible pressure sensors have attracted increasing interest because of their potential applications on wearable sensing devices for human−machine interface connections, but challenges regarding material cost, fabrication robustness, signal transduction, sensitivity improvement, detection range, and operation convenience still need to be overcome. Herein, with a simple, low-cost, and scalable approach, a flexible and wearable pressure-sensing device fabricated by utilizing filter paper as the solid support, poly(3,4-ethylenedioxythiophene) to enhance conductivity, and silver nanoparticles to provide a rougher surface is introduced. Sandwiching and laminating composite material layers with two thermoplastic polypropylene films lead to robust integration of sensing devices, where assembling four layers of composite materials results in the best sensitivity toward applied pressure. This practical pressure-sensing device possessing properties such as high sensitivity of 0.119 kPa −1 , high durability of 2000 operation cycles, and an ultralow energy consumption level of 10 −5 W is a promising candidate for contriving point-of-care wearable electronic devices and applying it to human−machine interface connections.
Programmable surface-patterned functional DNA density is achieved via manipulation of molecular-level defects through chemical lift-off lithography. Artificial SAM defects are well-tunable by a contact-induced reaction, enabling molecular environment guidance and DNA insertion to be spatially and quantitatively addressable. This straightforward molecular density control creates an advanced avenue toward fabricating multiplexed bioactive substrates.
The classical alkanethiol post-passivation can prevent nonspecific binding of nucleotide bases onto supporting substrates and help aptamers transition from a "lying down" to a "standing up" orientation. However, the surface probes display lower binding affinity towards targets than those in bulk solutions due to unsatisfied hybridization spaces on the alkanethiol passivated substrate. To overcome this challenge, an artificial defect-rich matrix possessing an aptamer "self-standing" property created by chemical lift-off lithography (CLL) is demonstrated. This approach provided artificial defects on a hydroxyl-terminated alkanethiol self-assembled monolayer (SAM), which allowed the insertion of thiolated aptamers. The diluted surface molecular environment assisted aptamers not only to "self-stand" on the surface, but also to separate from each other, providing a suitable surface aptamer density and sufficient space for capturing targets. With this approach, the binding affinity of the aptamer towards a target was comparable to solution-type probes, showing higher recognition efficiency than that in conventional methods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.