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Highly Photoluminescent and Stable N-Doped Carbon Dots as Nanoprobes for Hg2+ Detection
摘要： We developed a microreactor with porous copper fibers for synthesizing nitrogen-doped carbon dots (N-CDs) with a high stability and photoluminescence (PL) quantum yield (QY). By optimizing synthesis conditions, including the reaction temperature, flow rate, ethylenediamine dosage, and porosity of copper fibers, the N-CDs with a high PL QY of 73% were achieved. The PL QY of N-CDs was two times higher with copper fibers than without. The interrelations between the copper fibers with different porosities and the N-CDs were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). The results demonstrate that the elemental contents and surface functional groups of N-CDs are significantly influenced by the porosity of copper fibers. The N-CDs can be used to effectively and selectively detect Hg2+ ions with a good linear response in the 0~50 μM Hg2+ ions concentration range, and the lowest limit of detection (LOD) is 2.54 nM, suggesting that the N-CDs have great potential for applications in the fields of environmental and hazard detection. Further studies reveal that the different d orbital energy levels of Hg2+ compared to those of other metal ions can affect the efficiency of electron transfer and thereby result in their different response in fluorescence quenching towards N-CDs.
关键词： carbon dots,microreactor,Hg2+ detection,porous copper fibers
更新于2025-11-19 16:46:39
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A Continuous Synthesis of Polymethylmethacrylate Using a Microreactor Plant
摘要： We applied a microreactor to the synthesis of polymethylmethacrylate (PMMA) using a laboratory microreactor system with a production volume of 2–3 t per year, which enabled pseudo-continuous feeding by syringe pumps. When using a tube made of stainless steel, the values of the yield, number average molecular weight (Mn), and polydispersity index (PDI) reached 75.2%, 9.4×103, and 1.88, respectively. These results were in good accordance with the reported ones and a product with comparable properties was obtained. Then, we performed a continuous synthesis of PMMA for 8 h using a medium scale microreactor plant with a production volume of 100 t per year, which provided continuous feeding by triple cam driven pumps. When using a tube made of polytetrafluoroethylene (PTFE), it was confirmed that a product was continuously obtained for 8 h, whose yield, Mn, and PDI were on average 66.2%, 8.8×103, and 1.95, respectively. The variation in the yield, Mn, and PDI was within 5.7%, 4.5%, and 1.0%, respectively. For comparison, when using the laboratory microreactor system under the same reaction condition with a tube made of PTFE, the corresponding values of the yield, Mn, and PDI were 66.5%, 8.4×103, and 2.04, respectively. The difference in the results between the above two microreactor systems was 4.8% at a maximum (in Mn). Therefore, the synthesis of PMMA was continuously performed using the medium scale microreactor plant and the comparability of the reaction performance between the above two microreactor systems was ensured.
关键词： Microreactor Plant,Microreactor,Polymethylmethacrylate,Polymerization Reaction
更新于2025-09-23 15:23:52
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Enzymatic method of urea determination in LTCC microfluidic system based on absorption photometry
摘要： In this paper a novel microanalytical system based on absorption photometry for urea determination in small-volume biological samples is described. The developed microsystem with built-in microreactor with urease immobilised on its surface was fabricated using low temperature co-fired ceramics (LTCC) technology. For detection of the ammonium ions – product of urea hydrolysis, the modified Berthelot’s reaction was applied and conditions of this reaction were optimised in a way to be suitable for analysis in microsystems and for particular application, with special regards to very small alternation of urea concentration in culture medium. The best results were obtained for reagent R1 composed of: 180 mM sodium salicylate, 15 mM sodium nitroprusside, 2 mM EDTA in phosphate buffer solution of pH 7 and reagent R2 containing 16.9 mM sodium hypochlorite in phosphate buffer solution of pH 12. Linear concentration range of urea detection with the use of the developed LTCC microfluidic system for the selected flow rate of 4 μl/min, was in the range up to 1 mM, and the calculated lower limit of detection – 0.002 mM. The developed microsystem enables urea determination in samples of post-culture medium and of cells lysates of minimised volume c.a. 1 μl. Preliminary studies related to determination of urea in real samples, performed using hepatic cells lysates and post-culture medium were successful. As reference methods, commercially available tests were applied. The determined urea concentration measured by means of the QuantiChrom? and BioMaxima test and by the developed method based on the LTCC microanalytical system differs by c.a. 9% and 2% respectively. To the best of our knowledge, this is the first urea analysis microsystem for use in cells culture studies characterised by: the smallest volume of sample – 1 μl, long lifetime with stable response - reduced by 14%, through experimental time span of 30 days as well as suitability for quasi-monitoring of cells in vitro with sampling rate - 6 samples per hour.
关键词： LTCC technology,enzymatic microreactor,microfluidic systems,lab-on-a-chip,enzymatic urea determination,absorption photometry
更新于2025-09-23 15:22:29
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High-quality quantum dots for multiplexed bioimaging: A critical review
摘要： Bioimaging carried out using two or more fluorophores possessing different emission wavelength can be termed as a multicolor/multiplexed bioimaging technique. Traditionally, images are captured sequentially using multiple fluorophores having specific excitation and emission. For this purpose, multifunctional nanoprobes, such as organic fluorophores, metallic nanoparticles, semiconductor quantum dots, and carbon dots (CDs) are used. Among these fluorophores, quantum dots (QDs) have emerged as an ideal probe for multiplexed bioimaging due to their unique property of size tunable emission. However, the usage of quantum dots in bioimaging is limited due to their toxicity. Furthermore, the reproducibility of optical properties is cynical. These desirable properties, along with enhancement in quantum efficiency, photostability, fluorescence lifetime, etc. can be achieved using precision control over synthesis parameters. This review summarizes the desirable properties and synthesis methods of such superior QDs followed by their application in multiplexed imaging.
关键词： Multiplexed Imaging,Quantum dots,Microreactor,Bioimaging,Organic Dyes
更新于2025-09-19 17:13:59
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A UV‐LEDs based photomicroreactor for mechanistic insights and kinetic studies in the norbornadiene photoisomerization
摘要： In this work, we report a simple and inexpensive UV-LEDs based photomicroreactor assembly constructed by commercially available components. The photoisomerization of norbornadiene to quadricyclane was selected to validate this novel photomicroreactor design. Mass transport limitation was eliminated and indicated by dimensionless numbers Fo and DaII, and photons loss was evaluated considering the absorption and reflection of the microreactor walls. The solvents, photosensitizers and light sources selections were optimized for achieving better photochemical performance and mechanistic insights. The detailed comparison between the high-pressure mercury arc lamp and the UV-LEDs strip revealed great potential of UV-LEDs as appealing light source for photochemical transformations. Moreover, the reaction mechanism was thoroughly discussed and illustrated by the Jablonski diagram indicating electronic states transitions. According to possible intermediate steps, a kinetic model was proposed with the reaction rate constant being correlated with the photon flux, which is valuable for process optimization and further understanding reaction mechanisms.
关键词： photosensitization,reaction kinetics,microreactor,mass transport,UV-LED
更新于2025-09-19 17:13:59
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Rationally Designed a Double-Shell Dodecahedral Microreactor with Efficient Photo-electron Transfer: N-doped C Encapsulated Ultrafine In2O3 Nanoparticles
摘要： It is desirable but challenging to design efficient micro-/nanoreactors for chemical reactions. In this study, we fabricated mesoporous double-shelled hollow microreactor composed of N-doped C coated ultiafine In2O3 nanoparticles (N-C/In2O3 HD) by the thermolysis of dodecahedral In-based framworks in Ar atmosphere. The obtained N-C/In2O3 HD exhibited excellent photocatalytic activity toward photocatalytic oxidative hydroxylation of a series of arylboronic acids substrates, due to its enhanced optical absorption and efficient separation of photo-generated electron-hole pairs endowed by the unique structure and uniformly coated N-doped C layers. Furthermore, we found that O2?- was the critical active species in the process of photocatalytic oxidative hydroxylation of arylboronic acids, and the formation mechanism of this radical was also proposed. The theoretical calculation further confirmed the N-doped C layer acted as electron acceptor and revealed the microscopic charge carrier migration path via the In2O3/N-doped graphite interfaces i.e., the photo-generated electrons from hybrid states of In2O3, composed of In 5s and 2p orbitals, transferred into the hybrid states of N-doped graphite, composed of C 2p and N 2p orbitals. The present study may be helpful for understanding and designing carbon-based micro-/nanoreactors for photocatalytic reactions and can be useful for investigating other relevant micro-/nanoractors as well.
关键词： photocatalysis,nanoparticle,In2O3,microreactor,N-doped C
更新于2025-09-10 09:29:36
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Formation of BiFeO3 Nanoparticles Using Impinging Jets Microreactor
摘要： The influence of the reactants mixing in an impinging jets microreactor of the formation of single-phase nanocrystals of bismuth orthoferrite has been studied. The 30–100 nm amorphous particles are formed under the impinging jets microreactor conditions, which are converted in bismuth orthoferrite with mean crystallite size 17 nm at 420°С.
关键词： impinging jets microreactor,phase formation mechanism,bismuth ferrite
更新于2025-09-09 09:28:46