A review on synthesis of quantum dots and their biomedical applications

Quantum Dots (QDs) are ultra-fine nanometer-sized semiconductor particles with a core-shell structure possess both electrical and optical properties. Their unique ability to emit pure, monochromatic light on being exposed to light makes them extremely versatile in their applications. The color of the light emitted directly depends on their size and shape. Smaller QDs emit shorter wavelengths, closer to the violet end of the visible light spectrum (~380-450 nm), while larger QDs emit longer wavelengths i.e in reddish spectrum (~620-750 nm). Owing to their “tunability”, QDs can be exploited in a wide range of fluorescent, photonic, and electrochemical applications. QDs represent elements mainly from Group II-VI (e.g., CdSe) or Group III-V (e.g., InP) with the resultant optical and electronic properties of the quantum dots being somewhere between bulk semiconductor material and individual atoms or molecules. Besides applications in energy and photonics, they are under extensive investigation and development for use in disease diagnosis and therapy, specifically in the area of controlled drug delivery, biosensing and imaging. This review surveys the progress of research explores their properties, synthesis, applications, delivery systems in biology, and their toxicity

Fluorescent aptasensor for detection of live foodborne pathogens based on multicolor perovskite-quantum-dot-encoded DNA probes and dual-stirring-bar-assisted signal amplification / 药物分析学报

In this study,a fluorescent(FL)aptasensor was developed for on-site detection of live Salmonella typhimurium(S.T.)and Vibrio parahaemolyticus(V.P.).Complementary DNA(cDNA)of aptamer(Apt)-functionalized multicolor polyhedral oligomeric silsesquioxane-perovskite quantum dots(cDNA-POSS-PQDs)were used as encoded probes and combined with dual-stirring-bar-assisted signal amplification for pathogen quantification.In this system,bar 1 was labeled with the S.T.and V.P.Apts,and then bar 2 was functionalized with cDNA-POSS-PQDs.When S.T.and V.P.were introduced,pathogen-Apt complexes would form and be released into the supernatant from bar 1.Under agitation,the two complexes reached bar 2 and subsequently reacted with cDNA-POSS-PQDs,which were immobilized on MXene.Then,the encoded probes would be detached from bar 2 to generate FL signals in the supernatant.Notably,the pathogens can resume their free state and initiate next cycle.They swim between the two bars,and the FL signals can be gradually enhanced to maximum after several cycles.The FL signals from released encoded probes can be used to detect the analytes.In particular,live pathogens can be distinguished from dead ones by using an assay.The detection limits and linear range for S.T.and V.P.were 30 and 10 CFU/mL and 102-106 CFU/mL,respectively.Therefore,this assay has broad application potential for simultaneous on-site detection of various live pathogenic bacteria in water.

Efficacy of folate-coupled quantum dots immunomagnetic beads method for detecting circulating tumor cells in epithelial ovarian cancer and the association of circulating tumor cells with clinicopathological features / 肿瘤研究与临床

Objective:To explore the effectiveness of folate-coupled quantum dots (FA-QD) immunomagnetic beads method for detecting circulating tumor cells (CTC) in epithelial ovarian cancer and the association of CTC with clinicopathological features of tumor patients.Methods:A total of 67 ovarian cancer patients in Shanxi Provincial People's Hospital from August 2019 to January 2020 were selected. Ovarian cancer SKOV-3 cells were divided into 5 cell number gradients (0, 100, 150, 200, 300), the detection rates of CTC were compared by using epithelial cell adhesion molecule (EpCAM) immunomagnetic beads (single standard method) and FA-QD immunomagnetic beads method (double standard method). The number of CTC in peripheral blood of ovarian cancer patients was detected by using FA-QD immunomagnetic beads method, and those with positive CTC under fluorescence microscope were treated as CTC positive patients. The association of CTC with clinicopathological factors and tumor markers of tumor patients was analyzed.Results:The average capture efficiency rate of CTC in SKOV-3 cells detected by FA-QD immunomagnetic beads method (83.4%) was higher than that by EpCAM immunomagnetic beads method (70.3%). Among 67 patients of ovarian cancer, the proportion of CTC positive patients was 30.0% (3/10) in stage Ⅰ-Ⅱ, 91.9% (34/37) in stage Ⅲ, 95.0% (19/20) in stage Ⅳ, and the difference was statistically significant ( P < 0.05). The proportion of CTC positive patients with lymph node metastasis was higher than that of patients without lymph node metastasis [97.1% (33/34) vs. 69.7% (23/33)], and the difference was statistically significant ( P < 0.05). The proportion of CTC positive patients with human epididymis protein 4 (HE4)>110 pmol/L was lower than that of patients with HE4 ≤ 110 pmol/L [58.8% (10/17) vs. 92.0% (46/50)], and the difference was statistically significant ( P = 0.005). There were no statistically significant differences in the proportion of CTC positive patients stratified by age, menopause, pathological differentiation, distant metastasis, carbohydrate antigen (CA) 125, CA199, carcino-embryonic antigen (CEA) (all P > 0.05). Conclusions:FA-QD immunomagnetic beads method can effectively detect CTC in peripheral blood of patients with epithelial ovarian cancer. The level of CTC in patients with epithelial ovarian cancer is related to lymph node metastasis, clinical TNM stage and HE4 level.

Simple synthesis of photoluminescent carbon dots from a marine polysaccharide found in shark cartilage

BACKGROUND: For more than a decade, water-soluble, eco-friendly, biocompatible, and low-toxicity fluorescent nanomaterials have received considerable attention for their numerous in vivo and in vitro applications in biomedical imaging, disease diagnostics, and environmental monitoring. Owing to their tunable photoluminescence properties, carbon-based luminescent nanomaterials have shown great potential in bioimaging, photocatalysis, and biosensing among other applications. RESULTS: Marine environments provide excellent resources for the fabrication of these nanomaterials, because many marine organisms contain interesting trigger organic compounds that can be used as precursors. Herein, we synthesize multi-color emissive carbon dots (CDs) with an intrinsic photoluminescence quantum yield of 20.46%. These nanostructures were achieved through the one-step hydrothermal treatment of marine polysaccharide chondroitin sulfate, obtained from shark cartilage, in aqueous solution. CONCLUSIONS: We successfully demonstrate the low toxicity of our marine resource-derived CDs in zebrafish, and provide an initial assessment of their possible use as a bioimaging agent. Notably, the newly synthesized CDs localize in the intestines of zebrafish larvae, thereby indicating their biocompatibility and potential use as in vivo dyes.

Fluorescent labeling application of graphene oxide quantum dots in living human periodontal ligament stem cells / 医学研究生学报

ObjectiveNano-graphene oxide quantum dots (GOQDs) can be used to target fluorescent markers. The stem cell labeling is an important method in studying stem cell treatments. Our study aims to explore the possibility of using GOQDs as living cell fluorescent marker materials for human periodontal ligament stem cells (hPDLSCs), and to evaluate the biosecurity and effect as live cell fluorescence markers of GOQDs.Methods GOQDs were testified by TEM, DLS, UV-vis, and PL spectra. hPDLSCs were obtained by tissue cultivation and separated by single cell-derived colony selection. Then the source of the cells was carried out by immunocytochemical staining of anti-vimentin, anti-cytokeratin, and multipotent differentiation was used in the identification of stem cells. hPDLSCs were incubated with different concentrations of GOODs (0, 10, 25, and 50 μg/mL) for 24h and 72 h. Cytotoxicity and proliferation effects were determined using CCK-8, and cell cycles were detected using flow cytometry after the co-culture of GOQDs and hPDLSCs. The fluorescent labeling effect of GOQDs was tested using laser scanning confocal microscopy.ResultsThe characterization of GOQDs showed that the nanoparticles were evenly dispersed in water and showing blue light at 365 nm. TEM and DLS showed GOQDs had good dispersion, and the particle size was (6.36±1.41) nm. Immunocytochemical staining of anti-vimentin was positive while anti-cytokeratin was negative. The results of cytotoxicity showed there were no significant differences in cell activity after incubated with different concentrations of GOODs (0, 5, 10, 25, 50, 100, 200, and 400 μg/mL) (P>0.05), and there was no significant decrease in cell activity between 24h and 72h (P>0.05). There was no significant difference in the proportional distribution of G1, G2, and S phases between the two concentrations of GOQDs (0 μg/mL and 50 μg/mL) (P>0.05). Fluorescent images showed that GOQDs could enter the cell membrane and increase the fluorescence intensity at the concertation of 50 μg/mL.ConclusionGOQDs were confirmed to have good biocompatibility and could be used for live cell labeling of hPDLSCs.

Fluorescent labeling application of graphene oxide quantum dots in living human periodontal ligament stem cells / 医学研究生学报

ObjectiveNano-graphene oxide quantum dots (GOQDs) can be used to target fluorescent markers. The stem cell labeling is an important method in studying stem cell treatments. Our study aims to explore the possibility of using GOQDs as living cell fluorescent marker materials for human periodontal ligament stem cells (hPDLSCs), and to evaluate the biosecurity and effect as live cell fluorescence markers of GOQDs.Methods GOQDs were testified by TEM, DLS, UV-vis, and PL spectra. hPDLSCs were obtained by tissue cultivation and separated by single cell-derived colony selection. Then the source of the cells was carried out by immunocytochemical staining of anti-vimentin, anti-cytokeratin, and multipotent differentiation was used in the identification of stem cells. hPDLSCs were incubated with different concentrations of GOODs (0, 10, 25, and 50 μg/mL) for 24h and 72 h. Cytotoxicity and proliferation effects were determined using CCK-8, and cell cycles were detected using flow cytometry after the co-culture of GOQDs and hPDLSCs. The fluorescent labeling effect of GOQDs was tested using laser scanning confocal microscopy.ResultsThe characterization of GOQDs showed that the nanoparticles were evenly dispersed in water and showing blue light at 365 nm. TEM and DLS showed GOQDs had good dispersion, and the particle size was (6.36±1.41) nm. Immunocytochemical staining of anti-vimentin was positive while anti-cytokeratin was negative. The results of cytotoxicity showed there were no significant differences in cell activity after incubated with different concentrations of GOODs (0, 5, 10, 25, 50, 100, 200, and 400 μg/mL) (P>0.05), and there was no significant decrease in cell activity between 24h and 72h (P>0.05). There was no significant difference in the proportional distribution of G1, G2, and S phases between the two concentrations of GOQDs (0 μg/mL and 50 μg/mL) (P>0.05). Fluorescent images showed that GOQDs could enter the cell membrane and increase the fluorescence intensity at the concertation of 50 μg/mL.ConclusionGOQDs were confirmed to have good biocompatibility and could be used for live cell labeling of hPDLSCs.

Ovarian cancer cells targeting fluorescent-magnetic imaging dual-modal nanoprobe:from synthesis to imaging in vitro / 中华核医学与分子影像杂志

Objective To fabricate manganese-doped carbon quantum dots(Mn-CDs)@anti-human epididymis protein 4(HE4)monoclonal antibody(Mn-CDs@Anti-HE4 mAb)dual-modal fluorescent-magnetic nanoprobe for ovarian cancer cells targeting imaging,and evaluate its potential on fluorescent imaging and MRL Methods Mn-CDs were synthesized at 150 ℃ with solvothermal method.The average diameter,fluorescent capability and MRI efficiency were determined.The cytotoxicity of Mn-CDs in vitro was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium(MTS)assay with HO-8910 ovarian cancer stem cells and EA.hy926 human umbilical vein endothelial cells.Mn-CDs@Anti-HE4 mAb was fabricated with condensation reaction and characterized by ultraviolet(UV)absorption spectra.Fluorescence imaging and MRI in vitro was performed for cancer cell-targeting study.One-way analysis of variance and the least significant difference t test were used to analyze the data.Results The Mn-CDs with diameter of(4.64±0.85)nm showed a well-defined spherical morphology.The fluorescent spectra of Mn-CDs exhibited a typical excitation-dependent behavior with an excitation maximum at 360 nm and emission maximum at 440 nm.The T1 relaxation rate was(3.26±0.04)mmol ? L-1 ? s-1.The cytotoxicity tests in vitro showed that the survival rates of HO-8910 cells and EA.hy926 cells were both significantly different after treated with different concentrations of Mn-CDs(F= 1 947.509,260.174,both P<0.05),and there was no cytotoxicity in both HO-8910 cells and EA.hy926 cells at concentrations of MnCDs within 0-2.5 mg/ml(all P>0.05),while the survival rates of the two kinds of cells were descended with the increasing of concentration within 3.0-4.5 mg/ml(P<0.05).Mn-CDs@Anti-HE4 mAb could target HO-8910 cells on fluorescence imaging and MRI.Conclusions Mn-CDs@Anti-HE4 mAb,with good potential on fluorescence imaging,MRI and targeting ability,is successfully synthesized.It may provide a new method for early diagnosis of ovarian cancer.

Synthesis of transdermal aloesin loaded zinc oxide nanoparticles and its inhibitory effect on the activity of tyrosinase / 生物医学工程学杂志

Zinc oxide quantum dots (ZnO QDs) were synthesized by gel-sol method and employed as the transdermal aloesin (Alo) carriers. ZnO QDs were surface-functionalized with amino using aminopropyltriethoxysilane (APTES). Alo was covalently bonded on the surface of ZnO QDs via N,N'-carbonyldiimidazole to obtain Alo NPs, which were characterized by transmission electron microscope (TEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analyzer (TGA). TEM images showed that ZnO QDs were analogously sphere and monodisperse with a reasonably narrow size distribution, of which was around 4 nm. The size of Alo NPs increased to around 8 nm due to the surface modification. The intense bands at around 3 400 cm and 1 200 cm in the FTIR spectrum of Alo NPs from the vibration of -OH indicated the linkage of Alo on the surface of ZnO QDs. The results of TGA analysis showed that the mass ratio of ZnO QDs and Alo were 39.27% and 35.14%, respectively. The penetration of Alo NPs was much higher than raw Alo according to the passive penetration experiments with Franz-type diffusion cells instrument using full-thickness cavy skin, which manifested the improvement of the penetration for Alo delivered by ZnO QDs. The pH-controlled drug release behavior was investigated. At pH 7.4, only a small amount of Alo (1.45% ± 0.21%) had been released after 2 h. In contrast, as incubation at pH 5.0 of which pH was similar to endosomal environment, Alo was released very fast (87.63% ± 0.46% in 2 h) from Alo NPs, confirming that Alo NPs could response to the pH and realize the intracellular drug release. The inhibitory effect of Alo NPs on tyrosinase was in a dose dependent manner. When the concentration of Alo NPs was 12.5 μg/mL, the inhibition rate was up to 40.32% ± 1.57%. All the results show that the Alo NPs hold a great potential in transdermal tyrosinase inhibition.

Preparation of dual-modal nanoprobe for fluorescent-magnetic imaging with manganese-doped carbon quantum dots and imaging study in tumor bearing mice / 中华核医学与分子影像杂志

Objective@#To prepare manganese-doped carbon quantum dots (Mn-CDs) dual-modal nanoprobe for fluorescent-magnetic imaging, and evaluate its characteristics and potential on fluorescence imaging and MRI.@*Methods@#Mn-CDs were synthesized at 150 ℃. The form, diameter, component, fluorescent capability, T1 relaxation rate, stability and cytotoxicity of Mn-CDs in vivo were verified. The fluorescence imaging of HO-8910 tumor-bearing mice was performed on small animal imager, and the whole-body enhanced imaging was performed on 3.0 T MRI scanner. One-way analysis of variance was used to analyze the data.@*Results@#The Mn-CDs with the diameter of (4.64±0.85) nm showed a well-defined spherical morphology. The fluorescent spectra of Mn-CDs exhibited that the excitation maximum was at 360 nm and the emission maximum was at 440 nm. The T1 relaxation rate was (3.26±0.04) mmol·L-1·s-1. The Mn-CDs had good stability of fluorescent and magnetic imaging capability at 0, 0.25, 0.5, 0.75, 1.0 and 2 months at room temperature with no significant differences of fluorescent and magnetic signals (F=1.566 and 0.987, both P>0.05). After injection of 200 μl Mn-CDs (15 g/L), mice were all alive and had no viscera damage. The tumor could be observed obviously on fluorescence imaging at 5 min. Enhanced MRI showed that the tumor was unevenly enhanced and Mn-CDs were mainly cleared away through urinary system.@*Conclusion@#Mn-CDs are stable and have good potential on fluorescence imaging and MRI, which provides a promising multimodal imaging method for tumor detection and monitoring.

Preparation of dual-modal nanoprobe for fluorescent-magnetic imaging with manganese-doped car-bon quantum dots and imaging study in tumor bearing mice / 中华核医学与分子影像杂志

Objective To prepare manganese-doped carbon quantum dots ( Mn-CDs) dual-modal nanoprobe for fluorescent-magnetic imaging, and evaluate its characteristics and potential on fluorescence imaging and MRI. Methods Mn-CDs were synthesized at 150 ℃. The form, diameter, component, fluo-rescent capability, T1 relaxation rate, stability and cytotoxicity of Mn-CDs in vivo were verified. The fluores-cence imaging of HO-8910 tumor-bearing mice was performed on small animal imager, and the whole-body enhanced imaging was performed on 3.0 T MRI scanner. One-way analysis of variance was used to analyze the data. Results The Mn-CDs with the diameter of (4.64±0.85) nm showed a well-defined spherical morpholo-gy. The fluorescent spectra of Mn-CDs exhibited that the excitation maximum was at 360 nm and the emission maximum was at 440 nm. The T1 relaxation rate was (3.26±0.04) mmol·L-1·s-1. The Mn-CDs had good stability of fluorescent and magnetic imaging capability at 0, 0.25, 0.5, 0.75, 1.0 and 2 months at room tem-perature with no significant differences of fluorescent and magnetic signals ( F=1. 566 and 0. 987, both P>0. 05) . After injection of 200 μl Mn-CDs ( 15 g/L) , mice were all alive and had no viscera damage. The tumor could be observed obviously on fluorescence imaging at 5 min. Enhanced MRI showed that the tumor was unevenly enhanced and Mn-CDs were mainly cleared away through urinary system. Conclusion Mn-CDs are stable and have good potential on fluorescence imaging and MRI, which provides a promising multimodal im-aging method for tumor detection and monitoring.

Sistemas de nanopartículas poliméricas II: estructura, métodos de elaboración, características, propiedades, biofuncionalización y tecnologías de auto-ensamblaje capa por capa (layer-by-layer self-assembly) / Polymeric nanoparticle systems: structure, elaboration methods, characteristics, properties, biofunctionalization and self-assembly layer by layer technologies

Los materiales poliméricos han sido ampliamente investigados para aplicaciones biomédicas, teniendo especial relevancia cuando se encuentran en forma de micro- y nano-partículas. Últimamente se ha ampliado su campo de aplicación al ser conjugados con péptidos y ácidos nucleicos, por lo tanto, el interés en el estudio de este tipo de materiales, así como también en la formulación de nanoestructuras funcionalizadas como materiales, dispositivos y vehículos de transporte de agentes terapéuticos ha aumentado. Las recientes investigaciones en nanosistemas se inspiran en fenómenos naturales que estimulan la integración de señales moleculares y la mimetización de procesos a nivel celular, de tejidos y órganos. Tecnológicamente, la capacidad de obtener nanoestructuras esféricas mediante la combinación de materiales que presenten propiedades distintas a las que ningún otro material individual posee por sí solo, es lo que hace que las nanocápsulas sean particularmente atractivas. Las potenciales ventajas de los sistemas de nanopartículas de tipo polimérico se destacan a lo largo de cada parte de este artículo de revisión. El presente artículo aborda los aspectos más relevantes sobre la estructura, composición y algunos métodos de elaboración de los sistemas nanoparticulados. Además, expone algunos de los trabajos más recientes, centrados en sistemas de nanopartículas basados en polímeros dirigidos a la administración de agentes, publicados en artículos especializados de investigación y revisiones durante los últimos años.

Polymeric materials have been extensively investigated for biomedical applications including micro- and nanoparticles. Modern advances have broadened horizons for application with peptides and nucleic acids. Therefore, interests increased in the formulation of materials, devices and vehicles for transporting therapeutic agents in functionalized nanostructures. Recent nano-systems are inspired by natural phenomena that stimulate the integration of molecular signals and the mimicking of natural cellular processes, at tissue and organ levels. Technologically, the ability to obtain spherical nanostructures, which combine different properties, that no other single material possesses on its own, makes nanocapsules particularly attractive. Potential advantages over polymer nanoparticulate systems are highlighted throughout each part of this review article. Here, we address the most relevant aspects of structure, composition and methods of formulation of nanoparticulate systems. In addition, we outline some of the more recent works focusing on nanosized preparations, based on agent-directed polymers, found in specialized research articles that have emerged in the recent years.

Sistemas de nanopartículas poliméricas i: de biodetección y monitoreo de glucosa en diabetes a bioimagen, nano-oncología, terapia génica, ingeniería de tejidos / regeneración a nano-odontología / Polymer nanoparticle systems: from biodetection and glucose monitoring in diabetes to bioimaging, nano-oncology, gene therapy, tissue engineering / regeneration to nano-dentistry

Nanotecnología es la ciencia que involucra la síntesis de materiales en escala entre 1-100 nm (nanomateriales) es aplicable en diferentes áreas tales como medio ambiente, electrónica, alimentos, energía, entre otros. Los campos que serán relevantes dentro de esta revisión y explicados en detalle son la nanomedicina y la nano-odontología. Actualmente, en estas áreas los tres principales temas en desarrollo son específicamente en el sub-área de la nanobiotecnología y corresponden a: sensorización (biosensores/biodetección), diagnóstico (biomarcadores/bioimagen) y transportes de genes, proteínas o fármacos (sistemas de intercambio controlado en blancos sistémicos versus localizados). También se han presentado avances en bioaplicaciones como modelamientos de membranas, marcaje celular, entrega de agentes a blancos específicos, estrategias para prevención de enfermedades, ingeniería de tejidos, regeneración de órganos, estrategias de inmunoensayos y nano-oncología. Este artículo de revisión pretende abordar algunos de los aportes más relevantes, que tienen algunos de los trabajos recientes, sobre los sistemas de nanopartículas, principalmente aquellos dirigidos a terapias en áreas como diabetes, nano-oncología, terapia de fármacos y genes, mediante la técnica layer-by-layer y autoensamblado, muy utilizados también en ingeniería de tejidos y regeneración tisular, junto a un breve resumen de los avances que existen en el campo de la nano-odontología.

Nanotechnology is the science that involves the synthesis of materials in scale between 1-100 nm (nanomaterials) and is applicable in different areas such as environment, electronics, food, energy, among others. The fields that will be relevant within this review and explained in detail are nanomedicine and nano-dentistry. Currently, in these areas, the three main topics under development are specifically in the sub-area of nanobiotechnology and correspond to: sensorization (biosensors / biosensing), diagnostics (biomarkers / bioimaging) and transport of genes, proteins or drugs (exchange systems) controlled in systemic versus localized targets). Advances have also been presented in bioapplications such as membrane modeling, cell marking, delivery of agents to specific targets, strategies for disease prevention, tissue engineering, organ regeneration, immunoassay strategies and nano-oncology. This review article aims to address some of the most relevant contributions, some of the recent work, on nanoparticle systems, mainly those aimed at therapies in areas such as diabetes, nanooncology, drug and gene therapy, through the layer-by-layer and self-assembled technique, also widely used in tissue engineering and tissue regeneration, together with a brief summary of the advances that exist in the field of nano-dentistry.

Síntesis y caracterización de las propiedades ópticas de puntos cuánticos de CdSe y CdSe/ZnS / Synthesis and characterization of optic properties of CdSe and CdSe/ZnS quantum dots / Síntese e caracterização das propriedades ópticas do pontos quânticos de CdSe e CdSe/ZnS

Resumen Se prepararon puntos cuánticos de CdSe y CdSe/ZnS (núcleo/capa) con ácido oleico como agente estabilizante en medio orgánico y se examinaron las propiedades ópticas de los nanocristales obtenidos. En la obtención de CdSe, se estudió la influencia del O2 en la cinética de crecimiento de los puntos cuánticos. Durante los primeros 90 s, el crecimiento de los nanocristales en presencia de O2 fue 1,6 veces mayor que en atmósfera inerte. A pesar de este rápido crecimiento, el O2 afectó las propiedades ópticas de los nanocristales, formando bandas de absorción anchas y espectros de fluorescencia de baja intensidad. En contraste, los puntos cuánticos de CdSe sintetizados en atmósfera inerte presentaron picos de absorción bien definidos y fluorescencia aguda e intensa. Estas propiedades se intensificaron con la formación de un 10% de la monocapa de ZnS: para un núcleo de 2,50 nm, el rendimiento cuántico de fluorescencia (ΦFl) en la región del verde se incrementó de 5,5 % a 42,3%. El procedimiento de síntesis de nanocristales de CdSe/ZnS desarrollado con baja concentración de Zn2+ y con un exceso de S2" puede emplearse en la obtención de materiales con excelentes propiedades fotoluminiscentes para aplicaciones como biomarcadores, sensores, catálisis y celdas solares.

Abstract CdSe and CdSe/ZnS (core/shell) quantum dots with oleic acid as stabilizing agent in organic medium were prepared and their optical properties were examined. For CdSe synthesis, the influence of O2 in the growth kinetics of quantum dots was determined. In the first 90 s, the nanocrystals growth was 1.6 higher in presence of O2 than when reaction was carried out in N2 atmosphere. However, the growth rate with O2 not favorable because the nanocrystal optical properties were affected: wider absorption band and lower fluorescence that those obtained in inert atmosphere. Properties of CdSe nanocrystals synthesized in inert atmosphere were intensified with 10% of monolayer. For a core with 2.5 nm diameter, the fluorescence quantum yield (ΦF1) in the green region increased from 5.5% to 42.3%. The synthesis process of CdSe/ZnS nanocrystals developed with low concentration of Zn2+ and an excess of S2- can be used to obtain materials with excellent photoluminescent properties for applications such as biomarkers, sensors, catalysis, and solar cells.

Resumo Pontos quânticos CdSe e CdSe/ZnS (núcleo/ couraça) com ácido oleico como um agente de estabilização em um meio orgânico foi preparado e as propriedades ópticas dos nanocristais obtidos são examinados Na obtenção de CdSe, a influência da O2 foi estudada em cinética de crescimento de pontos quânticos. Durante o primeiro crescimento de 90 s dos nanocristais na presença de O2 foi de 1,6 vezes mais elevado do que em atmosfera inerte. Apesar deste crescimento rápido, O2 afecta as propriedades ópticas dos nanocristais, formando bandas de absorção ampla e espectros de fluorescência de baixa intensidade. Em contraste, CdSe sintetizados em atmosfera inerte mostrou picos bem definidos de absorção e fluorescência nítida e intensa. Estas propriedades são intensificadas pela formação de 10% da monocamada de ZnS: para um núcleo de 2,50 nm, o rendimento quântico de fluorescência (ΦFl) na região do verde aumentou de 5,5% para 42,3%. O procedimento de síntese de nanocristais de CdSe/ZnS desenvolvidos com baixa concentração de Zn2+ e o excesso de S2" pode ser utilizada na obtenção de materiais fotoluminescentes com excelentes propriedades para aplicações como biomarcadores, sensores, catálise e células solares.

The antimicrobial activity and application of graphene quantum dots in oral medicine / 口腔疾病防治

@#The abuse of antibiotics has been increasing bacterial resistance, which means there is a need to develop methods for the efficient detection and effective treatment of multiresistant bacterial infections. As one of graphene-based materials, graphene quantum dots (GQDs) have distinct mechanical, electrical, and optical properties, including a small size, a large surface area-to-volume ratio, biocompatibility, antimicrobial activity and tunable photoluminescence. Therefore, GQDs are expected to be widely used as antimicrobial materials, drug delivery carriers and photosensitizers in antibacterial applications. In this review, we focus on their synthesis, characteristics and antimicrobial applications in oral medicine.

Determination of Glucose Based on Carbon Quantum Dots as Peroxidase Mimetic Enzyme / 分析化学

Water soluble carbon quantum dots ( CQDs) were prepared by using soot as carbon source. The obtained CQDs showed an excellent intrinsic peroxidase-like activity, which could catalyze the oxidization of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2and thus resulted in color change. Glucose could react with dissolved oxygen to produce H2O2in the presence of glucose oxidase ( GOx) . A colorimetric method using CQDs as peroxidase mimetic enzyme was developed for glucose determination. When TMB was acted as a substrate, the effect of a series of conditions, such as temperature and pH on the catalytic activity of the obtained CQDs, was systematically studied. Under optimal conditions, e. g. pH 3. 5 and temperature 35℃, 0. 5 mmol/L TMB and 1 μg/mL CQDs, the absorbance at 652 nm showed linear response with glucose concentrations ranging from 0. 025 mmol/L to 0. 40 mmol/L, with detection limit of 5. 10 μmol/L (3σ/k). The proposed method exhibited excellent selectivity and the common substances did not interfere with detection of glucose. This method was successfully applied to detect glucose in real samples with recoveries of 95. 0%-105. 1% .

Detection of Arginine by AuNPs / CQDs Nanoprobes Based on Fluorescence Resonance Energy Transfer Effect / 分析化学

A novel method for rapid detection of arginine based on fluorescence resonance energy transfer effect (FRET) between carbon quantum dots ( CQDs) and gold nanoparticles ( AuNPs) was developed. Firstly, the CQDs with excellent fluorescence properties were synthesized by one-step microwave assisted method. The AuNPs/ CQDs composites were characterized and their quenching mechanism was analyzed. Then the amount of AuNPs/ CQDs, the pH value and the reaction time were optimal. Under the optimum conditions, the fluorescence system was used to detect the content of arginine, showing a good linear relationship ( R2 = 0. 993 ) between fluorescence intensity and concentration of arginine in the range of 0. 1-10. 0 μmol/ L, and the detection limit was 5. 8 nmol/ L. Finally, the content of arginine in grape juice was determined by this method with recoveries of 105. 4％ -110. 8％ , which indicated that the proposed FRET system had the potential for practical detection of arginine in fruit juice.

Amplification Effect of CdS Quantum Dots on Electrogenerated Chemiluminescence of Ru(bpy)32+and Its Application in Determination of Catechol / 分析化学

The effect of CdS quantum dots (QDs) on the electrochemiluminescence (ECL) signal of Ru(bpy)32+ was studied. It was found that CdS QDs could enhance the anodic ECL of Ru(bpy)32+ by 4 times. The sensitization mechanism was discussed and the influence factors including concentrations of Ru (bpy)32+ and CdS QDs, pH of solution and scan rate on ECL intensity were investigated. On the basis of quenching effect of catechol on the ECL signal of CdS QDs-Ru(bpy)32+,a system for sensitive determination of catechol was established with a detection limit of 5.5 nmol/L (S/N=3). This method was applied to the detection of catechol in tea sample with satisfactory results.

Synthesis of Bifunctional Graphene Quantum Dots and Its Application in Fluorescence Detection of pH and Cell Imaging / 分析化学

Functional groups may change the electrical characteristics of graphene quantum dots,thus leading to the improvement of their properties and related applications. To improve the optical properties,we designed and synthesized pentaethylene hexamine and dodecylamine functionalized graphene quantum dots (PEHA-GQD-DA). Citric acid was mixed with pentaethylene hexamine and heated at 170℃ for 0.5 h. Then dodecylamine was added and the reaction was continued at 160℃ for 1.5 h to obtain PEHA-GQD-DA. The Yesults revealed that the PEHA-GQD-DA was composed of the graphene sheets from 1 nm to 3 nm,and their edges contained abundant functional groups. The introduction of pentaethylene hexamine greatly improved the fluorescence emission. The fluorescence quantum yield reached 72.7%,which was much higher than that of the GQD prepared by the thermal hydrolysis of single citric acid. The introduction of dodecylamine created a special amphiphilic structure that allows the quantum dots more likely to enter cell through the phospholipid bilayer of cell membrane. The PEHA-GQD-DA exhibited an excellent optical behavior for pH value of the medium. Within pH range of 1.0-6.5, the fluorescence intensity increased with the increase of pH value. The fluorescence spectrum sensitively changed with the change of pH value. There was a good linear relationship between the maximum emission wavelength and the pH value. When the pH was in the range of 6.5-12.0,the fluorescence spectrum didn't change with the change of pH value. However, its fluorescence intensity linearly decreased with the increase of pH value. The existence of common inorganic ions and organic small molecules does not interfere with pH response of the quantum dots. The PEHA-GQD-DA has been successfully applied to fluorescent detection of pH value in water samples and Hela cell imaging.

Clinical significances of the synchronous detection of mucin 1 and collagen Ⅳ in breast cancer by using quantum dots immunofluorescence imaging technique / 肿瘤研究与临床

Objective@#To investigate the relationship between the expression of mucin 1 and collagen Ⅳ and the clinical characteristics in invasive breast cancer by using the quantum dots immunofluorescence imaging technique.@*Methods@#The expressions of mucin 1 and collagen Ⅳ were detected simultaneously by quantum dots immunofluorescence imaging technique in 94 cases of breast cancer from July 2007 to July 2010 in Affiliated Hospital of Guilin Medical University. The correlation of mucin 1 and collagen Ⅳ quantitative parameters with clinicopathological features and the prognosis were also analyzed.@*Results@#The positive rates of mucin 1 in human breast cancer tissues marked by quantum dots immunofluorescence imaging technique and immunohistochemistry were 73.4 % (69/94) and 69.1 % (65/94), the positive rates of collagen Ⅳ were 53.2 % (50/94) and 47.9 % (45/94), and the differences were not statistically significant (both P > 0.05) Quantum dots immunofluorescence imaging technique was consistent with conventional immunohistochemistry (IHC) in detecting the expressions of mucin 1 and collagen Ⅳ in human breast cancer tissues (κ = 0.763, P = 0.000; κ=0.759, P = 0.000). The expression of mucin 1 was negatively correlated with collagen Ⅳ (r = -0.883, P < 0.01). The expressions of mucin 1 and collagen Ⅳ were respectively associated with tumor size (F = 3.683, P = 0.029; F = 4.922, P = 0.009), histological grading (F = 3.529, P = 0.033; F = 3.912, P = 0.023), lymph node metastasis (t = -4.868, P = 0.000; t = 3.868, P = 0.000), pathological stage (t = -8.337, P = 0.000; t = 5.962, P = 0.000) and 5-year disease free survival rate (both P = 0.000), and the differences were statistically significant (all P < 0.05).@*Conclusion@#The co-detection of mucin 1 and collagen Ⅳ by using quantum dots immunofluorescence imaging technique provides direct evidence determining the biologic behaviors of breast cancer and evaluating the prognosis.

Effects of CdTe quantum dots on the content of cytochrome P450 in rat liver / 中华劳动卫生职业病杂志

Objective@#The effect and mechanism of cadmium telluride quantum dots (CdTe QDs) on cytochrome P450 (CYP450) in the liver of rat were investigated.@*Methods@#CdTe QDs (Ex 350 nm, Em 600 nm) were incubated with microsomes in final concentrations (0.5, 5, 50 μmol/L) using rat liver. And the content of CYP450 was determined by mixed incubation system as time (15, 30, 45 min) went on. Relationship also was detected between particle sizes (Em 620, 580, 540 nm; CdTe QDs-2, CdTe QDs-3, CdTe QDs-4) and expression of CYP450. Twenty male Wistar rats were randomly divided into exposed groups at various concentrations (0.25, 2.5 and 12.5 μmol/kg) of CdTe QDs via tail vein injection, the control group was injected with PBS.@*Results@#In vitro, CdTe QDs(0.5, 5, 50 μmol/L) could significantly increase the content of CYP450 in rat liver microsomes(P<0.05), which increased first and then decreased with the dose adding. Moreover, the trend along with the exposure time (15, 30, 45 min) was the same as that in dosages at certain concentration (P<0.01). For different particle sizes, the smaller CdTe QDs were, the higher content increased, the content of CYP450 in group CdTe QDs-4 was the highest (P<0.05). In vivo, experiment proved that CdTe QDs (0.25, 2.5 and 12.5 μmol/kg) could obviously induce the expression of CYP450 (P<0.01). The content level showed a tendency to rise and then fall.@*Conclusion@#CdTe QDs could promote the content of CYP450 in rat liver microsomes, it indicated that CdTe QDs had dose-effect relationship both in vivo and vitro. There was a certain relationship in time-effect. In addition, the smaller particle size was, the greater impact had.