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 su...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.展开更多
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...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.展开更多
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 ...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.展开更多
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-ciga...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.展开更多
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 ...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.展开更多
基金financially supported by the National Natural Science Foundation of China (NSFC, No. 21535006 and No. 21705132)the Fundamental Research Funds for the Central Universities (XDJK2017C065)
文摘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.
基金financially supported by the National Natural Science Foundation of China (NSFC, No. 21535006)
文摘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.
基金supported by the National Natural Science Foundation of China(21535006)
文摘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.
基金supported by National Natural Science Foundation of China(Nos.21535006,21906130)Southwest University Postdoctoral Science Foundation(Nos.5330600027,5330600094)+2 种基金the Natural Sciences and Engineering Research Council of Canadathe Canadian Institutes of Health Research,Alberta InnovatesAlberta Health
文摘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.
基金supported by the National Natural Science Foundation of China (21535006)the Fundamental Research Funds for the Central Universities (XDJK2018C088)
文摘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.
