Development of nitrogen and sulfur-doped carbon dots for cellular imaging

Heteroatom-doped carbon dots(CDs) have attracted extensive interest because of their improved electronic and fluorescence properties with heteroatom doping. In this study, a new synthetic method for nitrogen(N) and sulfur(S)-doped CDs was developed via a hydrothermal method using methionine and citric acid as raw materials. The as-prepared CDs exhibit excellent optical properties and good biocompatibility. The spherical N,S-doped CDs have an average diameter of 5 nm. They consist of C, O, N and S, and take on excellent water solubility due to the hydroxyl and carboxyl, amino groups on the surface.The CDs have a photoluminescence quantum yield of 13.8% using quinine sulfate as a reference; the average fluorescence lifetime of the CDs was 3.67 ns. The CDs solution present good photoluminescence properties, and the maximum excitation wavelength and emission wavelength locate at 330 nm and405 nm, respectively. In addition, their fluorescence intensity almost does not change under the conditions of acid, alkali, and high salt, which indicated their anti-photobleaching property and good light stability. Based on the good biocompatibility and strong fluorescence emission of the CDs, they can be used as fluorescent imaging reagents.

Does Argan Oil Supplementation Affect Metabolic Parameters and Behavior in Wistar Rats?

Argan oil is renowned for its particular biochemical profile: high-fat oleic and linoleic acids, tocopherols, sterols, polyphenols. This composition gives it nutritional, therapeutic and preventive properties against dermatological, metabolic and proliferative diseases. The composition of argan oil assigns its benefits to mental health;it would be provided with possible effects on the prevention and/or cure of stress related disorder. This work aims to evaluate the impact of argan oil dietary on the behavioral response, biochemical and hematological constants and histological profiles of adrenal involved in emotional responses to stress. The variation of these parameters was evaluated in Wistar rats receiving dietary 10 ml/Kg/day of argan oil, starting from weaning, for 13 weeks. Our results show that supplementation has resulted in an increase in locomotor activity, reduced sensitivity to frightening environments with sex dependent variation. Moreover, lipid markers, corticosterone and lymphocytes show a rising trend. If the important role of argan oil diet in cardio-metabolic health is generally well recognized;for mental health, it is the first study that needs further investigation linking between the nervous system, inflammation parameters and metabolism.

Microbiological Assessment and Antimicrobials’ Use in an Infectious Diseases Department in Mali

The use of antimicrobials without microbiological proof is frequent and contributes to the emergence of resistance. The aim was to identify the organisms isolated during laboratory examinations and the type of antimicrobials consumed by patients hospitalized to Infectious Diseases’ Clinic. This is a cross-sectional and analytical study, carried out from January 1 to December 31, 2017 in the Infectious Diseases Department of Point “G” Teaching Hospital in Mali. All biological specimens from patients during the study period were analyzed. In total, 322 patients benefited from microbiological test, with a mean age of 40.9 ± 12.2 years (range 15 and 74 years) with a sex ratio of 0.93. Only 5.6% of patients were HIV negative. In all participants, a total of 658 microbiological specimen were taken, 224 (34.0%) identified at least one pathogen including bacteria in more than a half of the cases (58.5%). On the report of bacteriological analysis, the most frequently identified organisms were Mycobacterium tuberculosis (42.2%) mainly in sputum;Escherichia coli (24.2%) and Klebsiella pneumoniae (7.8%) commonly in urine and Gardnerella vaginalis (7.0%) exclusively in vaginal secretions. Candida albicans (5/8) and Cryptococcus neoformans (3/8) were the most common fungi while Plasmodium falciparum (96.4%) represented the parasite frequently found in blood. From a therapeutic standpoint, 1143 antimicrobials were prescribed to 322 admitted patients, i.e. 3.55 anti-infectives per patient. Antibiotics (excluding tuberculosis drugs), antiparasitics and antifungals represented respectively 46.2%;18.8% and 15.1% of anti-infectives. Antibiotic therapy was effective in 274 (85.1%) patients and among them, only 76 (27.7%) cases were based on microbiological evidence. Antibiotics are the most widely used antimicrobials in an infectious disease department. Empiric treatments are common but must be minimized by the search for microbiological evidence.

Photoluminescence of carbon quantum dots:coarsely adjusted by quantum confinement effects and finely by surface trap states

Photoluminescence(PL) mechanism of carbon quantum dots(CQDs) remains controversial up to now even though a lot of approaches have been made. In order to do that, herein a PL color ladder from blue to near infrared of CQDs with the absolute quantum yields higher than 70% were prepared via a one-pot hydrothermal synthesis route and separated by silica gel column.Time-correlated single photon counting measurements suggest that the electron transition takes in effect in the PL progress of the crystalline core-shell structured CQDs, and the PL properties could be coarsely adjusted by tuning the size of the crystalline carbon core owing to quantum confinement effects, and finely adjusted by changing the surface functional groups consisted shell owing to surface trap states,respectively. Both coarse and fine adjustments of PL, as optical and photoelectrical characterizations and density-functional theory(DFT) calculations have demonstrated, make it possible for top-level design and precise synthesis of new CQDs with specific optical properties.

Aggregation-induced emission enhancement of yellow photoluminescent carbon dots for highly selective detection of environmental and intracellular copper(Ⅱ) ions

Carbon dots (CDs) are prepared through a simple one-step hydrothermal treatment of o-phenylendiamine (OPD) and show yellow photoluminescent (PL) emission under the ultraviolet excitation, which can be further enhanced by Cu2+ ions owing to Cu2+ ions induced aggregation of OPD-CDs through the coordination of Cu2+ with amino groups on the surface of OPD-CDs. The aggregation induced emission enhancement (AIEE) property enables it feasible to develop a simple, sensitive and selective method to detect environmental and intracellular copper (Ⅱ) ions. The limit of detection as lowas 0.28 μmol/L (3σ/k) and a dynamic range from 0.5 μmol/L to 40 μmol/L make it veryeasy to detect the copper content inwater samples, such as river closure reservoir. Furthermore, fluorescence imaging of intracellular Cu2+ suggests that the AIEE features of OPD-CDs specific to Cu2+ ions can be also applied in biological systems.

Arsenic species in electronic cigarettes:Determination and potential health risk

Human exposure to contaminants from electronic cigarettes(e-cigarettes)and the associated health effects are poorly understood.There has been no report on the speciation of arsenic in e-liquid(solution used for e-cigarettes)and aerosols.We report here determination of arsenic species in e-liquids and aerosols generated from vaping the e-liquid.Seventeen e-liquid samples of major brands,purchased from local and online stores in Canada and China,were analyzed for arsenic species using high-performance liquid chromatography and inductively coupled plasma mass spectrometry.Aerosols condensed from vaping the eliquids were also analyzed and compared for arsenic species.Six arsenic species were detected,including inorganic arsenate(iAsⅤ),arsenite(iAsⅢ),monomethylarsonic acid(MMA),and three new arsenic species not reported previously.In e-liquids,iAsⅢwas detected in 59%,iAsⅤin 94%,and MMA in 47%of the samples.In the condensate of aerosols from vaping the e-liquids,iAsⅢwas detected in 100%,iAsv in 88%,and MMA in 13%of the samples.Inorganic arsenic species were predominant in e-liquids and aerosols of e-cigarettes.The concentration of iAsⅢin the condensate of aerosols(median 3.27μg/kg)was significantly higher than that in the e-liquid(median 1.08μg/kg)samples.The concentration of inorganic arsenic in the vaping air was approximately 3.4μg/m3,which approaches to the permissible exposure limit(10μg/m3)set by the United States Occupational Safety and Health Administration(OSHA).According to the Environmental Protection Agency’s unit risk factor(4.3×10-3 perμg/m3)for inhalation exposure to inorganic arsenic in the air,the estimated excess lung cancer risk from lifetime exposure to inorganic arsenic in the ecigarette vaping air(3.4μg/m3),assuming e-cigarette vaping at 1%of the time,is as high as1.5×10-4.These results raise health concerns over the exposure to arsenic from electronic cigarettes.

Carbon dots prepared for fluorescence and chemiluminescence sensing

Carbon dots(CDs) have attracted considerable research interest in recent years due to their unique optical properties, chemical inertness, facile synthesis from a wide range of starting materials, and advantages over classic quantum dots and organic dyes.Various methods have been developed for preparing the CDs, including chemical oxidation, hydro/solvothermal method,electrochemical method, microwave-assisted synthesis, and direct carbonization method. Importantly, the superior electronic properties of CDs including efficient light harvesting and prominent photoinduced electron transfer have aroused considerable attention in fluorescence(FL) and chemiluminescence(CL) sensing field. In this review, we aim to demonstrate the recent progress of CDs in the synthesis, FL and CL sensing applications. This review gives new insights into how to use different synthetic methods to tune the structure of the CDs, with the major focus on FL and CL sensing.

Magnetic Bead‑Based Sandwich Immunoassay for Viral Pathogen Detection by Employing Gold Nanoparticle as Carrier

Enzyme-linked immunosorbent assay(ELISA)provides a convenient way for the detection of viral pathogens.However,conventional ELISA performed on mirowell plates suffers from poor sensitivity,laborious coating and complicated blocking procedures.Herein,we designed a sensitive colorimetric immunoassay by taking advantages of the enrichment and isolation ability of magnetic beads(MBs)and the high loading capacity of gold nanoparticles(AuNPs)for detecting respiratory syncytial virus(RSV)as a pathogen model.RSV was selectively captured and preconcentrated from samples with antibodies functionalized MBs,followed by binding with antibodies labeled AuNPs,which carrying a large amount of alkaline phosphatase(ALP)molecules for colorimetric signal amplification by catalyzing the dephosphorylation of non-colored pNPP to generate colored product pNP.After optimizing the experimental conditions based on the principle of low nonspecific signal,low cost,and high sensitivity,the analytical sensitivity of the developed immunoassay can be improved to 0.27 pg/mL,which is over sevenfold higher than that of commercially available RSV ELISA kits(2 pg/mL).In addition,the total assay time was less than 2.5 h without any pretreatment,which is much more rapid than other reported assays.Therefore,the proposed immunoassay holds great promise for the fabrication of rapid,sensitive,and economic method for the viral pathogen detection.