A coordination-driven SERS platform for trace detection of a nerve agent hydrolysis product using a plasmonic metal-organic framework.

A plasmonic metal-organic framework-based SERS platform with specific coordination capability and high Raman enhancement has been reported to ultrasensitively detect a nerve agent hydrolysis product in gas and solution phases.

Fluorescent poly(tannic acid)-based nanoprobes for selective and sensitive detection of bismuth ions.

Herein, blue luminescent fluorescent poly(tannic acid) nanoparticles (FPTA NPs) were fabricated through chemical degradation of poly(tannic acid) large particles using HO, and the obtained FPTA NPs exhibited excellent water dispersibility, great fluorescence stability, and relatively high quantum yield. More importantly, based on the dynamic quenching and chelation enhanced quenching effect between FPTA NPs and bismuth ions (Bi), a fluorescence method for the rapid identification and detection of Bi was developed. With the increase of Bi, the fluorescence of FPTA NPs could be quenched gradually; the linear range was 0.

Cationic fluorescent carbon dots with solution ultra-stability and its rapid/on-site sensing application for HClO.

Carbon dots (CDs) as a remarkable fluorescent nanomaterial have the advantages of easy preparation, good photostability and high sensitivity. However, the poor aqueous solution stability of carbon dots largely limited their practical application due to the characteristic of easily forming precipitation for long time storage. Here, a kind of cationic fluorescent carbon dots CDs-P(Ph) was designed by introducing a cationic compound, (4-carboxybutyl) triphenyl phosphonium bromide, to construct an electrostatic shell outside the dots.

Folic Acid Adjustive Polydopamine Organic Nanoparticles Based Fluorescent Probe for the Selective Detection of Mercury Ions.

Polydopamine fluorescent organic nanomaterials present unique physicochemical and biological properties, which have great potential application in bio-imaging and chemical sensors. Here, folic acid (FA) adjustive polydopamine (PDA) fluorescent organic nanoparticles (FA-PDA FONs) were prepared by a facile one-pot self-polymerization strategy using dopamine (DA) and FA as precursors under mild conditions. The as-prepared FA-PDA FONs had an average size of 1.

Electrical performance of monolayer MoStransistor with MoSnanobelt metallic edges as electrodes.

The contact electrodes have great influence on the performance of monolayer MoSdevices. In this paper, monolayer MoSand MoSnanobelts were synthesized on SiO/Si substrates via the chemical vapor deposition method. By using wet and dry transfer process, MoSnanobelt metallic edges were designed as the source/drain contact electrodes of monolayer MoSfield effect transistor.

Visual and Rapid Detection of Nerve Agent Mimics in Gas and Solution Phase by a Simple Fluorescent Probe.

Chemical nerve agents are highly toxic organophosphorus compounds that are easy to obtain and can be utilized by terrorists to threaten homeland security and human safety. Those organophosphorus nerve agents contain nucleophilic ability that can react with acetylcholinesterase leading to muscular paralysis and human death. Therefore, there is great importance to explore a reliable and simple method to detect chemical nerve agents.

Online Quantitative Analysis of Chlorine Contents in Chlorinated Paraffins by Facile Raman Spectroscopy.

Online analysis of industrial chemicals is extremely important for managing product quality and performance. The chlorine (Cl) content is one of the most important technical metrics for chlorinated paraffins (CPs), and the conventional approaches to estimate Cl contents require transforming the Cl element to chloride followed by quantitative analysis with either titration or instrumentation, which are normally tedious and time-consuming and cannot simultaneously guide the industrial production. Here, we developed a rapid, real-time, and online approach to determine the Cl content of CPs with facile Raman spectroscopy.

Phosphorylation-Dependent SERS Readout for Activity Assay of Protein Kinase A in Cell Extracts.

Protein kinases are key regulators of cell function, the abnormal activity of which may induce several human diseases, including cancers. Therefore, it is of great significance to develop a sensitive and reliable method for assaying protein kinase activities in real biological samples. Here, we report the phosphorylation-dependent surface-enhanced Raman scattering (SERS) readout of spermine-functionalized silver nanoparticles (AgNPs) for protein kinase A (PKA) activity assay in cell extracts.

Effect of cation replacement on the phase stability of formamidinium lead iodide perovskite.

First-principles calculations have been performed to study the effect of cation replacement with methylammonium (MA), Cs, and Rb on the properties of formamidinium lead iodide (FAPbI) perovskite. It is found that these dopants could improve the stability of the desired α phase of FAPbI at reduced temperature by lowering the transition temperature between the perovskite cubic α phase and nonperovskite hexagonal δ phase. Interestingly, the optical absorption properties and the effective masses of holes of FAPbI perovskite are only slightly affected.

A turn-on fluorescent probe with a dansyl fluorophore for hydrogen sulfide sensing.

Hydrogen sulfide (HS) is a biologically relevant molecule that has been newly identified as a gasotransmitter and is also a toxic gaseous pollutant. In this study, we report on a metal complex fluorescent probe to achieve the sensitive detection of HS in a fluorescent "turn-on" mode. The probe bears a dansyl fluorophore with multidentate ligands for coordination with copper ions.

Graphene Oxide: From Tunable Structures to Diverse Luminescence Behaviors.

Since the first discovery of luminescent graphene oxide (GO), exponentially increasing investigations on the tunable structures and surfaces for modulating its optical properties have struggled to expand applications in imaging, sensing, biomedical diagnostics, and so on. Here, the latest works on reconstructing or modifying the structures and surfaces of GO to achieve diverse luminescence are systematically reviewed, including fluorescence, electroluminescence, and chemiluminescence. Moreover, the fundamental difficulties of the investigations and applications of luminescent GO nanomaterials are clarified to inspire more constructive thoughts for expanding their application boundaries.

Improved phase stability of the CsPbI perovskite via organic cation doping.

We have studied the effect of organic cation doping with dimethylammonium (DMA), ethylammonium (EA), and guanidinium (GA) on the properties of the CsPbI perovskite by performing first-principles calculations. It was found that these dopants, especially DMA, can significantly improve the phase stability of the desired α phase of CsPbI by compressing the transition temperature between the photoactive α phase (cubic perovskite structure) and the photoinactive δ phase (orthorhombic structure). However, the incorporation of organic cations decreases the absorption coefficient of the CsPbI perovskite in the visible spectrum.

Membrane-Penetrating Carbon Quantum Dots for Imaging Nucleic Acid Structures in Live Organisms.

The dynamics of DNA and RNA structures in live cells are important for understanding cell behaviors, such as transcription activity, protein expression, cell apoptosis, and hereditary disease, but are challenging to monitor in live organisms in real time. The difficulty is largely due to the lack of photostable imaging probes that can distinguish between DNA and RNA, and more importantly, are capable of crossing multiple membrane barriers ranging from the cell/organelle to the tissue/organ level. We report the discovery of a cationic carbon quantum dot (cQD) probe that emits spectrally distinguishable fluorescence upon binding with double-stranded DNA and single-stranded RNA in live cells, thereby enabling real-time monitoring of DNA and RNA localization and motion.

Sticky-flares for in situ monitoring of human telomerase RNA in living cells.

Human telomerase RNA (hTR), a template of telomerase for telomeric repeat synthesis, was used to reflect the telomerase activity and act as a potential target of antitumor therapy. Here, we report a novel DNA-conjugated AuNP probe termed sticky-flares for the in situ detection of intracellular human telomerase RNA. The sticky-flares probe is capable of entering living cells directly without any auxiliary and recognizing the binding domain of human telomerase RNA.

Ratiometric Fluorescent Biosensor for Visual Discrimination of Cancer Cells with Different Telomerase Expression Levels.

Telomerase is inactive in normal somatic cells but highly activated in tumor cells to maintain their indefinite proliferation and immortal phenotype. As a specific marker for the generation and progress of almost all tumors, the detection of telomerase activity by classical PCR techniques has served in the biological research of tumors. However, the detection of in situ telomerase activity in cell extracts to evaluate the malignancy, progress, and metastasis of tumors remains a daunting challenge.

Dynamic mapping of spontaneously produced HS in the entire cell space and in live animals using a rationally designed molecular switch.

Hydrogen sulfide (H2S) is a key signaling molecule in the cytoprotection, vascular mediation and neurotransmission of living organisms. In-depth understanding of its production, trafficking, and transformation in cells is very important in the way H2S mediates cellular signal transductions and organism functions; it also motivates the development of H2S probes and imaging technologies. A fundamental challenge, however, is how to engineer probes with sensitivity and cellular penetrability that allow detection of spontaneous production of H2S in the entire cell space and live animals.

Click-Functionalized SERS Nanoprobes with Improved Labeling Efficiency and Capability for Cancer Cell Imaging.

Precise identification and detection of cancer cells using nanoparticle probes are critically important for early cancer diagnosis and subsequent therapy. We herein develop novel folate receptor (FR)-targeted surface-enhanced Raman scattering (SERS) nanoprobes for cancer cell imaging based on a click coupling strategy. A Raman-active derivative (5,5'-dithiobis(2-nitrobenzoic acid)-N (DNBA-N)) is designed with a disulfide bond for covalently anchoring to the surface of hollow gold nanoparticles (HAuNPs) and a terminal azide group for facilitating highly efficient conjugation with the bioligand.

A dual-colored ratiometric-fluorescent oligonucleotide probe for the detection of human telomerase RNA in cell extracts.

Human telomerase RNA (hTR), which is one component of telomerase, was deemed to be a biomarker to monitor tumor cells due to its different expression levels in tumor cells and normal somatic cells. Thus far, plentiful fluorescent probes have been designed to investigate nucleic acids. However, most of them are limited since they are time-consuming, require professional operators and even result in false positive signals in the cellular environment.

Real-Time Discrimination and Versatile Profiling of Spontaneous Reactive Oxygen Species in Living Organisms with a Single Fluorescent Probe.

Fluorescent probes are powerful tools for the investigations of reactive oxygen species (ROS) in living organisms by visualization and imaging. However, the multiparallel assays of several ROS with multiple probes are often limited by the available number of spectrally nonoverlapping chromophores together with large invasive effects and discrepant biological locations. Meanwhile, the spontaneous ROS profilings in various living organs/tissues are also limited by the penetration capability of probes across different biological barriers and the stability in reactive in vivo environments.

Atomic Oxygen Tailored Graphene Oxide Nanosheets Emissions for Multicolor Cellular Imaging.

Graphene oxide (GO) has been widely used as a fluorescence quencher, but its luminescent properties, especially tailor-made controlling emission colors, have been seldom reported due to its heterogeneous structures. Herein, we demonstrated a novel chemical oxidative strategy to tune GO emissions from brown to cyan without changing excitation wavelength. The precise tuning is simply achieved by varying reaction times of GO nanosheets in piranha solution, but there is no need for complex chromatography separation procedures.

Label-free surface-enhanced Raman scattering imaging to monitor the metabolism of antitumor drug 6-mercaptopurine in living cells.

The molecular processes of drugs from cellular uptake to intracellular distribution as well as the intracellular interaction with the target molecule are critically important for the development of new antitumor drugs. In this work, we have successfully developed a label-free surface-enhanced Raman scattering (SERS) technique to monitor and visualize the metabolism of antitumor drug 6-mercaptopurine in living cells. It has been clearly demonstrated that Au@Ag NPs exhibit an excellent Raman enhancement effect to both 6-mercaptopurine and its metabolic product 6-mercaptopurine-ribose.

Inkjet-printed silver nanoparticle paper detects airborne species from crystalline explosives and their ultratrace residues in open environment.

An electronic nose can detect highly volatile chemicals in foods, drugs, and environments, but it is still very much a challenge to detect the odors from crystalline compounds (e.g., solid explosives) with a low vapor pressure using the present chemosensing techniques in such way as a dog's olfactory system can do.

Inkjet printing lanthanide doped nanorods test paper for visual assays of nitroaromatic explosives.

The facile and sensitive strategies for detections of nitroaromatic explosives are highly desirable in many challenging environments, especially for homeland security against terrorism. Here, we inkjet printed polyethylenimine (PEI)-coated Ce, Tb co-doped NaGdF4 nanorods (NaGdF4:Ce/Tb NRs) onto common filter paper to construct test paper for visual and instant detections of a typical explosive 2,4,6-trinitrophenol (TNP). Polyethylenimine molecules not only facilitate the formation of uniform NaGdF4 nanorods but also provide specific recognized sites for TNP by the acid-base pairing interaction.

A chemically reactive Raman probe for ultrasensitively monitoring and imaging the in vivo generation of femtomolar oxidative species as induced by anti-tumor drugs in living cells.

A chemically reactive Raman probe has been developed for ultrasensitively monitoring and imaging the in vivo generation of femtomolar oxidative species as induced by anti-tumor drugs in living cells.

Surface-enhanced Raman scattering chip for femtomolar detection of mercuric ion (II) by ligand exchange.

The chemical sensing for the convenient detection of mercuric ion (II) (Hg(2+)) have been widely explored with the use of various sensing materials and techniques. It still remains a challenge to achieve ultrasensitive but simple, rapid, and inexpensive detection to metal ions. Here we report a surface-enhanced Raman scattering (SERS) chip for the femtomolar (fM) detection of Hg(2+) by employing silver-coated gold nanoparticles (Au@Ag NPs) together with an organic ligand.