Recyclable Colorimetric Detection of Trivalent Cations in Aqueous Media Using Zwitterionic Gold Nanoparticles

This report describes a colorimetric assay for trivalent metal cations (M³⁺) using gold nanoparticles (AuNPs)-modified with oppositely charged thiols that can form intermolecular zwitterionic surfaces. Zwitterionic AuNPs (Zw-AuNPs) are stable in high-salt solutions and well-dispersed in a wide range of pH values. M³⁺ including Fe³⁺, Al³⁺, and Cr³⁺ can effectively trigger the aggregation of Zw-AuNPs by interfering with their surface potential, and aggregated AuNPs can be regenerated and recycled by removing M³⁺. In our approach, the output signal can be observed by the naked eye within a micromolar (μM) concentration range. Uniquely, our assay is capable of discriminating Fe³⁺ from Fe²⁺, which is challenging using traditional approaches. More importantly, Zw-AuNPs can be stored stably at room temperature for a long period (3 months) with constant detection performance. Both the cost-effectiveness and the long shelf life make Zw-AuNPs ideal for detecting M³⁺ in resource-poor and remote areas

Tandem Synthesis of α‑Diazoketones from 1,3-Diketones

A highly efficient synthesis of α-diazoketone was achieved by simply stirring the mixture of 1,3-diketone, TsN₃, and MeNH₂ in EtOH. It was a tandem reaction including a novel primary amine-catalyzed Regitz diazo transfer of 1,3-diketone and a novel primary amine-mediated C–C bond cleavage of 2-diazo-1,3-diketone

Universal Coating from Electrostatic Self-Assembly to Prevent Multidrug-Resistant Bacterial Colonization on Medical Devices and Solid Surfaces

We provide a facile and scalable strategy for preparing gold nanoparticles (AuNPs)-based antibacterial coating on a variety of surfaces through electrostatic self-assembly. AuNPs conjugated with 4,6-diamino-2-pyrimidinethiol (DAPT, not antibacterial by itself), AuDAPT, can form stable coating on different substrates made from polyethylene (PS), polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), polydimethylsiloxane (PDMS), and SiO₂ in one step. Such a coating can efficiently eradicate pathogenic Gram-negative bacteria and even multidrug-resistant (MDR) mutants without causing any side-effect such as cytotoxicity, hemolysis, coagulation, and inflammation. We show that immobilized AuDAPT, instead of AuDAPT released from the substrate, is responsible for killing the bacteria and that the antimicrobial components do not enter into the environment to cause secondary contamination to breed drug resistance. Advantages for such coating include applicability on a broad range of surfaces, low cost, stability, high antibacterial efficiency, good biocompatibility, and low risk in antibiotics pollution; these advantages may be particularly helpful in preventing infections that involve medical devices

A Highly Sensitive, Dual-Readout Assay Based on Gold Nanoparticles for Organophosphorus and Carbamate Pesticides

This report presents a highly sensitive, rhodamine B-covered gold nanoparticle (RB-AuNP) -based assay with dual readouts (colorimetric and fluorometric) for detecting organophosphorus and carbamate pesticides in complex solutions. The detection mechanism is based on the fact that these pesticides can inhibit the activity of acetylcholinesterase (AChE), thus preventing the generation of thiocholine (which turns the RB-AuNP solutions blue and unquenches the fluorescence of RB simultaneously). The color of the RB-AuNP solution remains red and the fluorescence of RB remains quenched. By use of this dual-readout assay, the lowest detectable concentrations for several kinds of pesticides including carbaryl, diazinon, malathion, and phorate were measured to be 0.1, 0.1, 0.3, and 1 μg/L, respectively, all of which are much lower than the maximum residue limits (MRL) as reported in the European Union pesticides database as well as those from the U.S. Department Agriculture (USDA). This assay allows detection of pesticides in real samples such as agricultural products and river water. The results in detecting pesticide residues collected from food samples via this method agree well with those from high-performance liquid chromatography (HPLC). This simple assay is therefore suitable for sensing pesticides in complex samples, especially in combination with other portable platforms

Tandem Synthesis of 3‑Chloro-4-iodoisoxazoles from 1‑Copper(I) Alkynes, Dichloroformaldoxime, and Molecular Iodine

A tandem synthesis for structurally novel 3-chloro-4-iodoisoxazoles was developed by simply mixing 1-copper­(I) alkynes, dichloro­formaldoxime, and molecular iodine together. The combination of 1-copper­(I) alkyne and molecular iodine was well used as a synthetic equivalent of 1-iodoalkyne without the need for tedious preparation, purification, and storage of 1-iodoalkyne

Synthesis of <i>N</i>‑Sulfonyl Arylaldimines Developed by Retesting an Old Process

By simply heating the mixture of an arylaldehyde and a sulfonylisocyanate in a solvent or in neat form under catalyst- and additive-free conditions, the desired <i>N</i>-sulfonylimine was produced with the release of carbon dioxide. The method is characterized by its unique clean efficiency, convenience, and scalability, but it was reported to fail half a century ago

Tandem Synthesis of 3‑Halo-5-Substituted Isoxazoles from 1‑Copper(I) Alkynes and Dihaloformaldoximes

A tandem synthesis of 3-halo-5-substituted isoxazoles has been developed from 1-copper­(I) alkynes and dihaloformaldoximes under base-free conditions. Thus, 1,3-dipolar cycloaddition and all its drawbacks can now be avoided completely

Tandem Reaction of 1‑Copper(I) Alkynes for the Synthesis of 1,4,5-Trisubstituted 5‑Chloro-1,2,3-triazoles

A novel tandem reaction of 1-copper­(I) alkynes with azides (cycloaddition) and then NCS (electrophilic substitution) was developed as an efficient method for the synthesis of 1,4,5-trisubstituted 5-chloro-1,2,3-triazoles. The method offers a rare example that a tandem reaction of an organometallic substrate does not involve in the reactivity of the metal–carbon bond in the first step

Mixing-to-Answer Iodide Sensing with Commercial Chemicals

We develop a convenient, colorimetric assay (Au/PEI) for rapid iodide (I^–) determination that can be prepared facilely by mixing commercially available chemicals including tetrachloroauric acid (HAuCl₄) and poly­(ether imide) (PEI), and the assay can be carried out directly by adding the samples to the assay without any pretreatment and additional procedure. Au/PEI operates on the principle that I^– accelerates the formation of Au NPs, which leads to a visible color change from light yellow to red for naked-eye readout with high specificity. We integrate our assay on solid devices including gel hybrids (Au/PEI/GH) and filter paper (Au/PEI paper) to satisfy the demand of point-of-care testing and justify the practicality by detecting I^– in lake water that was supplemented with 10, 20, or 40 μM of I^–. Au/PEI/GH with the limit of detection of 0.35 μM can satisfy the detection of drinking water based on the guidelines (1.2 μM) set by the Chinese government, and Au/PEI paper can be used even after 1 year of storage. Such assays provide a convenient and straightforward choice for routine, on-site I^– tests

Data_Sheet_1_Evaluating occupational exposures of dental nurses: A retrospective study.PDF

ObjectiveThe objective of this study was to investigate occupational blood-borne pathogen exposure among dental nurses and their attitudes toward infected patients, as well as the effectiveness of the training course, to provide a scientific basis for improving the quality of safety management in the dental hospital.Materials and methodsThe study was conducted using questionnaires administered from November 2019 to December 2019 in three hospitals in Sichuan Province, China. Frequencies for answers were calculated and presented as percentages.ResultsIn total, 257 valid questionnaires were returned. Most (61.9%) nurses stated that they were involved in occupational exposure. Among them, 154 had experienced sharp injuries, and the syringe needle was the most common instrument for injuries (45.8%). Twenty-two individuals had mucosal exposure, and the proportion of eye exposure was the highest (90.9%). Only associations between training and mucosal membrane exposure were found; however, the relevance was weak (r = 0.141). Of the participants, 86.4% felt morally responsible for taking care of patients with infectious diseases, and most (92.6%) said they would continue with this career.ConclusionOccupational exposure, particularly to sharp injuries, was common in medical care among dental nurses; however, vocational training had little effect on their incidence. As dental nurses still have positive attitudes toward patients with infectious diseases, more effective training should be conducted.</p