Water-soluble Quantum Dots Research Articles

Fabrication of core-shell quantum dots microbeads with high stability, enhanced sensitivity and potential application in C-reactive protein (CRP) and procalcitonin (PCT) immunochromatography in vitro diagnostic reagents

Cardiovascular and cerebrovascular diseases represent the leading causes of mortality among middle-aged and elderly populations in China, with inflammation identified as a significant contributing factor. Consequently, the early diagnosis and management of inflammation are of paramount importance. C-reactive protein (CRP) and procalcitonin (PCT) serve as biomarkers for myocardial inflammation. In this study, we developed a quantum dot immunochromatographic strip that was capable of simultaneously detecting these two biomarkers with enhanced sensitivity and specificity. The comb amphiphilic poly (octadecyl-alt-polyethylene glycol) was synthesized through an amide reaction, which was employed to coat oil-soluble quantum dots, thereby transforming them into water-soluble quantum dots microbeads suitable for the coupling with biological macromolecules. These quantum dots microbeads were utilized as luminescent materials in the immunochromatographic strip for the concurrent detection of CRP and PCT. The assay required only 100 μL of sample and provided results within 10 min, demonstrating commendable precision, stability, sensitivity, and accuracy. Clinical evaluations confirmed that the developed CRP and PCT quantum dots immunochromatographic test strips were accurate and reliable, underscoring their significant potential for practical routine clinical application in the early accurate diagnosis of myocardial inflammation.

Enhancing capacitance performance of functional group assisted carbon quantum dots derived from turmeric plant waste

Supercapacitors have attracted significant attention in modern devices as a promising solution for electrical energy storage due to their remarkable capability to undergo rapid charge and discharge cycles. While various materials are employed in the construction of supercapacitors, carbon-based materials emerge as a predominant choice within the commercial realm. In present report, our intention is to develop an effective supercapacitor device derived from natural biomass. Therefore, we have synthesized water soluble, monodisperse and fluorescent carbon quantum dots (CQDs) from turmeric leaves (Curcuma caesia) via a single step hydrothermal carbonization. Further, the doctor blade technique was employed to coat a layer of CQDs on stainless steel substrate using PVA as a binder. We observed the functional groups associated with QDs triggers the fast diffusion of ions and transmission of electrons with conducting substrate and electrolyte and thereby effectively charge and discharge mechanism. The supercapacitor based on carbon quantum dots (CQDs) based electrode exhibits exceptional performance characteristics with a remarkable specific capacitance of 468 F/g and highest energy density of 78.6 Wh/kg, superior to the values reported for most carbon-based supercapacitors. Further, we demonstrated the light dependent capacitive enhancement by depositing a thin P3HT layer over CQDs. Moreover, CQDs-based supercapacitor achieves a maximum power density of 733.2 W/kg when operated in a 1 M KOH electrolyte solution and an excellent capacitive retention of about 80 % even after 5000 cycles.

Water-Soluble Quantum Dots for Inkjet Printing Color Conversion Films with Simultaneous High Efficiency and Stability.

Water-soluble quantum dots (QDs) are necessary to prepare patterned pixels or films for high-resolution displays with less environmental burden but are very limited by the trade-off between photoluminescence and stability of QDs. In this work, we proposed synthesizing water-soluble QDs with simultaneous excellent luminescence properties and high stability by coating the amphiphilic poly(maleic anhydride-alt-1-octadecene)-ethanol amine (PMAO-EA) polymer on the surface of silane-treated QDs. These coated QDs show a photoluminescence quantum yield (PLQY) as high as 94%, and they have good photoluminescence stability against light irradiation and thermal attacks, owing to the suppression of the nonradiative recombination by the polymer layer and the isolation of oxygen and water by the silica layer. The water-soluble QDs, mixed with ethylene glycol, enable inkjet printing of QD color conversion films (QD-CCFs) with an average diameter of 68 μm for each pixel and a high PLQY of 91%. The QD-CCFs are demonstrated to fabricate red-emitting mini-LEDs by combining with blue mini-LED chips, which have an external quantum efficiency as high as 25.86% and a luminance of 2.44 × 107 cd/m2. We believe that the proposed strategy is applicable to other water-soluble QDs and paves an avenue for inkjet printing environmentally friendly QD-CCFs for mini/micro-LED displays.

Water soluble silicon quantum dot based fluorescence immunoassay probe for C-reactive protein (CRP) detection

Silicon quantum dot (SiQD) based water soluble fluorescence immunoassay probe with aggregation induced emission features (AIE) was developed for the sensitive detection of C-reactive protein (CRP) biomarker. The solid state and solution phase photophysical properties of SiQD attributed from AIE effect was studied successfully. Later the ability of CRP antibody functionalized SiQD against the detection CRP antigen was evaluated systematically. The method relies on the decrease in fluorescence intensity of CRP antibody functionalized SiQD (CRPAb) upon the gradual addition of CRP antigen (CRPAg) via antigen-antibody interaction. The intensity of the antibody functionalized fluorophore quenched linearly by the addition of CRPAg within the concentration range of 50–150 nM and the limit of detection (LOD) was as sensitive as about 0.89 nM. Detection mechanism was assigned further by evaluating the interaction that exists between SiQD-CRPAb and CRPAg, which suggests that the effective complexation through a lock and key mechanism could be the plausible reason behind the fluorescence quenching of SiQD-CRPAb in presence of CRPAg. The solid state fluorescence features of SiQD arises from AIE phenomena which suggest that as a promising alternative to conventional QDs and organic fluorophores, integration of SiQD with lateral flow strips could result in powerful eco-friendly point-of-care device for in vitro diagnosis and the detection of other biomarkers.

Carbon quantum dot fluorescent probe for labeling and imaging of stellate cell on liver frozen section below freezing point

The targeted labeling imaging of stellate cells on liver frozen section by immunofluorescence is a very promising visualization technique to study the distribution of stellate cells in the liver. In this study, water soluble carbon quantum dots that can emit blue, green and yellow fluorescence are synthesized by the hydrothermal method, and their sizes are 3.2, 3.7, and 4.3 nm, respectively. The three carbon quantum dots have good fluorescence stability, and the quantum yields are 36.1%, 26.3% and 21%, respectively. When the mass fraction of KCl in the blue carbon quantum dot dispersion system is 13%, it still maintains the liquid state at −30 °C. The final fluorescent probe is obtained after the carbon quantum dots are coupled with the secondary antibody, spectral characterizations confirm that the conjugate probe still maintains protein immunoactivity and has good stability. Cell experiments prove that the probe has good biocompatibility, the rabbit anti-mouse Desmin antibody is used as the primary antibody, the results of cellular immunofluorescence imaging and flow cytometry show that the probe can specifically label hepatic stellate cell at −20 °C. The results of liver frozen section experiments show that hepatic stellate cell can be specifically targeted and labeled by the fluorescent probe. This labeling technology provides an important technical means for elucidating the structure and function of the liver at the cellular level, exploring the liver pathological change, and designing and developing drug.

Phase transferred and non-coated, water soluble perovskite quantum dots for biocompatibility and sensing.

Despite the excellent optoelectronic properties exhibited by CsPbBr3 QDs (PQDs) for sensing applications, their poor resistance to water does not allow their utilization as probes to detect analytes in aqueous media. The present work provides water soluble PQDs (dispersed in water) prepared by an appropriate phase engineering of the ligand. The dicarboxylate functional ligands at a particular pH allow the protonated state to form solvated carboxyl dimers, which interconnects PQDs, thus avoiding Ostwald ripening and enhancing the photoluminescence quantum yield (PLQY). As a proof of concept, this probe was applied to detect bioamines in water, namely histamine, hexamethylenediamine, phenethylamine, dopamine and thiamine. The probe is highly selective to histamine at concentrations below 500 nM and this selectivity of histamine over dopamine is very interesting and rarely reported. More importantly, this work offers a standard protocol for transferring PQDs from the organic to aqueous phase, for the detection of such biomolecules in water.

Glutathione-Capped CdTe Quantum Dots Based Sensors for Detection of H2O2 and Enrofloxacin in Foods Samples.

Additives and antibiotic abuse during food production and processing are among the key factors affecting food safety. The efficient and rapid detection of hazardous substances in food is of crucial relevance to ensure food safety. In this study, a water-soluble quantum dot with glutathione as a ligand was synthesized as a fluorescent probe by hydrothermal method to achieve the detection and analysis of H2O2. The detection limits were 0.61 μM in water and 68 μM in milk. Meanwhile, it was used as a fluorescent donor probe and manganese dioxide nanosheets were used as a fluorescent acceptor probe in combination with an immunoassay platform to achieve the rapid detection and analysis of enrofloxacin (ENR) in a variety of foods with detection limits of 0.05-0.25 ng/mL in foods. The proposed systems provided new ideas for the construction of fluorescence sensors with high sensitivity.

Effects of Zn (II) on the Optical Properties of CdTe Quantum Dots and Their Photoluminescence Response to Lead Ion

Water-soluble CdTe quantum dots (QDs) have been utilized as photoluminescence probes for the detection of metal ions such as Pb2+, Hg2+, Cd2+, etc. We initially developed highly photoluminescence (PL) Zn-doped CdTe for toxic ions detection. A study on the changes of optical properties of Zn-doped CdTe and CdTe QDs when exposed to Pb2+ suggested that Pb2+ could act as a surface passivating agent to reduce Te2- dangling bonds while Zn2+ dopant stabilizes the QDs surface against ambient oxidation. The results demonstrated herein provide useful understandings of the interactions between water-soluble QDs and metal ions. These results suggest further applications of QDs in sensing metal ions.

Fabrication of cell penetrating peptide labelled biodegradable poly(methacrylamide) nanoparticles for delivery of doxorubicin in HeLa cells

Advancements in cancer nano-therapeutics have led to the development of new and improved drug delivery systems but challenges still persist in the form of several limitations such as ineffective drug distribution, poor water solubility, and drug degradation. In lieu of this, the aim of this work is the development of a highly efficient nanomaterial based drug delivery system to overcome these limitations. In this work, we have successfully developed a theranostic platform where biodegradable polymeric nanoparticles have been used to reduce drug toxicity, control drug release, and provide biocompatibility with enhanced bioimaging. Anticancer drug, doxorubicin (DOX) was encapsulated in polymeric nanoparticles composed of P(N-(3-aminopropyl) methacrylamide) homopolymer, P(APMA), bearing primary amines for further modification. Water soluble CdTe quantum dots (QDs) were used as the fluorescent tag. The encapsulation efficiency of QDs-DOX conjugates into polymeric nanoparticles was found to be very high. To enhance the cellular internalization, a cell penetrating peptide BP100 (KKLFKKILKYL-Amide) was also attached on the surface of these polymeric nanoparticles and characterized using confocal microscopy. The drug release from the nanoconjugates at acidic pH showed enhanced internalization and growth inhibition in HeLa cells. Therefore, the synthesized conjugates can act as promising candidate for the successful treatment of cancer.

Solvothermal Synthesis of Fluorescent Carbon Quantum Dots by Using Vanillin as Carbon Source

As a new zero-optic luminescent material, carbon quantum points are widely focused and sustained, and many researchers are trying to use simple and fast methods and stable, good carbon sources to be prepared with a good fluorescent properties of carbon quantum dots. In this paper, carbon quantum dots were synthesized by solvothermal method with vanillin as carbon source, and the effects of solvothermal temperature and time on the luminescence properties of carbon quantum dots were explored. Then, carbon quantum dots were characterized by X-ray diffraction analysis, transmission electron microscopy analysis, infrared spectrum analysis, fluorescence spectrum analysis. Research results showed that ethanol solvent with vanillin as a carbon source by solvothermal method could synthesize good water soluble carbon quantum dots with weak crystallization, and its size was about 10 nm. This carbon quantum dots had obvious excitation wavelength dependence and produce blue light, which had potential application value in ion fluorescence probe or cell labeling.

In situ growth of water soluble CdS quantum dots by electron beam radiation and its cytotoxicity on mouse embryonic osteoblast precursor MC3T3-E1 cells in vitro

In situ growth of water soluble CdS quantum dots by electron beam radiation and its cytotoxicity on mouse embryonic osteoblast precursor MC3T3-E1 cells in vitro

Synthesis and characterization of CdTe QDs capped with a branched 3MB3MP ligand and fluorescent switching detection of H2O2

Label free turn-on detection of H2O2 using water-soluble CdTe quantum dots modified with a novel multifunctional branched ligand.

Synthetic Approaches, Modification Strategies and the Application of Quantum Dots in the Sensing of Priority Pollutants

Polycyclic aromatic hydrocarbons (PAHs) and nitro-aromatic compounds (NACs) are two classifications of environmental pollutants that have become a source of health concerns. As a result, there have been several efforts towards the development of analytical methods that are efficient and affordable that can sense these pollutants. In recent decades, a wide range of techniques has been developed for the detection of pollutants present in the environment. Among these different techniques, the use of semiconductor nanomaterials, also known as quantum dots, has continued to gain more attention in sensing because of the optical properties that make them useful in the identification and differentiation of pollutants in water bodies. Reported studies have shown great improvement in the sensing of these pollutants. This review article starts with an introduction on two types of organic pollutants, namely polycyclic aromatic hydrocarbons and nitro-aromatic explosives. This is then followed by different quantum dots used in sensing applications. Then, a detailed discussion on different groups of quantum dots, such as carbon-based quantum dots, binary and ternary quantum dots and quantum dot composites, and their application in the sensing of organic pollutants is presented. Different studies on the comparison of water-soluble quantum dots and organic-soluble quantum dots of a fluorescence sensing mechanism are reviewed. Then, different approaches on the improvement of their sensitivity and selectivity in addition to challenges associated with some of these approaches are also discussed. The review is concluded by looking at different mechanisms in the sensing of polycyclic aromatic hydrocarbons and nitro-aromatic compounds.

Cover Feature: Visible‐Light‐Driven Oxidative Cleavage of Alkenes Using Water‐Soluble CdSe Quantum Dots (ChemSusChem 22/2021)

The Cover Feature shows the oxidative cleavage of alkenes and oxidation of sulfides via water soluble CdSe quantum dots. The reactions were carried out in the water with oxygen as oxidant, with turnover numbers up to 37000. In a word, this approach is green and sustainable. More information can be found in the Full Paper by J. Li et al.

Positive Sorption Behaviors in the Ligand Exchanges for Water-Soluble Quantum Dots and a Strategy for Specific Targeting.

N,N,N',N'-Tetramethylethylenediamine (TMEDA) and ethylenediamine (EDA) were investigated in-depth in the ligand exchanges for water-soluble CdSe quantum dots (QDs). TMEDA could assist the phase transfer of QDs from apolar solvents to the aqueous solutions as stabilized by mercaptopropionic acid (MPA). We successfully maintained the stability of a series of MPA-capped QDs of different ligand densities for NMR characterizations in aqueous solutions. The proton NMR spectroscopies of MPA of the binding state were used to analyze the ligand densities on the surface of QDs, which were not explored in the past. The binding thermodynamics of the surface ligands of QDs, as analyzed using the Hill equation, demonstrated a positive promoting effect and possible interactions between ligands. EDA in the purification process underwent a spontaneous adsorption with two-stage thermodynamic behaviors as characterized by isothermal titration calorimetry. Due to the positive role of the already adsorbed ligands, excess EDA would further attach to the surface of QDs in the form of non-bonded physisorption, greatly improving the quantum yield (QY) of QDs, and the ligand of this part would almost not change the stability of QDs. We proposed a strategy for the preparation of aqueous QDs with a high QY, followed by fluorescence quenching-enhancement cycles caused by purification-adsorption operations. The strategy made it possible for the preparation of functional QDs with small molecules after purification operations. Kinetics of the sorption of ligands on the surface of QDs were determined by fluorescence spectroscopy. Modified pseudo-second-order kinetics after consideration of the ligand-ligand interaction effect could well analyze the kinetic data. This kinetic model had advantages over the previous ligand exchange model in terms of accuracy, reproducibility, and physical significance. Finally, we used the above strategy for the design of fluorescent QDs for bioimaging of lysosomes, mitochondria, and cancer cells. This work can simplify the preparation of multifunctional fluorescent QDs and avoid complicated ligand design.

Preparation of AgInS2 quantum dots and their application for Pb2+ detection based on fluorescence quenching effect

Water soluble AgInS2 quantum dots (AIS QDs) were successfully prepared by an environmentally friendly one-pot water phase method using glutathione (GSH) as the stabilizing agent. The crystal structure, morphology, size, chemical states, and optical properties of as-prepared AIS QDs were characterized through X-ray diffraction (XRD), Scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FTIR), Ultraviolet–visible spectrophotometer (UV–vis) and Photoluminescence spectrometer (PL). Factors affecting the fluorescence intensity of AIS QDs including reaction solution pH value, fluorescence test temperature and concentration of AIS QDs were investigated. The fluorescence stability of AIS QDs and the selectivity of AIS QDs toward Pb2+ detection was also evaluated. Under optimized test conditions, three excellent linear relationships ((F0−F)/F0=27.938CPb2+−0.002(R=0.998), (F0−F)/F0=10.362CPb2+−0.005(R=0.997), (F0−F)/F0=6.554CPb2+−0.240(R=0.9993) were achieved between the concentration of Pb2+ and the relative fluorescence quenching amount of AIS QDs in the range of 9–96 nM, 48–434 nM and 193–530 nM, respectively. The detection limit was 4 nM and the recovery was in the range of 92.2%–102.6%. Our method had wide detection range, excellent selectivity, high sensitivity and easy operability, and could be applied for the content determination of Pb2+ in water. The possible fluorescence quenching mechanism of AIS QDs by Pb2+ was discussed in detail and the dynamic quenching mechanism of light-induced electron transfer was put forward.

Multi-functionalized carbon aerogels derived from chitosan

Carbon aerogels are prepared by a thermal treating-freeze drying approach from chitosan, with glycine hydrochloride ionic liquid (IL) acting as solvent and nitrogen source. Different post-treatments such as ball milling and high temperature carbonization are employed to functionalize the obtained carbon aerogels with tuned properties, making it promising candidates as fluorescence material (NACs-Q), electrode material (FDC-800) and catalyst support (NACPd-C). NACs-Q is water-soluble quantum dot with average particle sizes of 3.8 nm, presenting excitation-/emission-independent and pH-sensitive properties, which could be used as sensor for testing acetone vapor or an “on-off-on” sensor for detections of Fe3+ and vitamin C in fruits. FDC-800 exhibits fluffy lamellar structure with developed micro-mesopores and nitrogen-containing groups on their surfaces, which is beneficial for building flexible solid-state supercapacitor with excellent performance, delivering a capacitance of 208F/g at 0.5 A/g, and achieving an energy density of 7.2 W h/kg at a power density of 50 W/kg. Moreover, NACPd-C can be used as catalyst for phenol hydrogenation, and phenol conversion of 100% with cyclohexanone selectivity of 98.3% is achieved, due to the synergetic effects of the Pd active-site, the N-containing groups, and the Lewis acid sites on the support.

Synthesis of near-infrared-emitting type-II In(Zn)P/ZnTe (core/shell) quantum dots

InP-based quantum dots (QDs) are considered promising candidates for replacing Cd-based QDs and ideal light emitters for next-generation displays. However, their spectral windows are confined to visible wavelengths, which restricts their applicability beyond displays. Thus, non-toxic colloidal QDs with the potential to extend the spectral window are highly desirable for many practical applications. Here, near-infrared-emitting type-II In(Zn)P/ZnTe (core/shell) QD heterostructures are fabricated. As the ZnTe shell grows on an In(Zn)P QD core, the absorption band redshifts owing to the decreased optical band gap. Near-infrared photoluminescent (PL) emission by type-II In(Zn)P/ZnTe (core/shell) QDs is realized by introducing an outer shell comprising ZnSeS passivation layers. The PL emission range of the resulting type-II In(Zn)P/ZnTe/ZnSeS (core/shell/shell) QDs can be tuned by varying the In(Zn)P core diameter and ZnTe shell thickness. Meanwhile, the proposed QDs also exhibit a prolonged exciton lifetime of 387 ns indicates the type-II characteristics. Moreover, the ZnSeS passivation layers enable surface modification while preserving the optical and chemical stabilities, resulting in water-soluble QDs. Importantly, heavy-metal-free near-infrared-emitting type-II In(Zn)P/ZnTe (core/shell) QDs have immense potential to increase the utilization of such materials in biomedical and energy applications requiring nontoxicity and near-infrared emission.

Synthesis of silicon nanowire and crystalline carbon quantum dots heterostructure and study of photo response and photoluminescence property

Silicon nanowire based heterostrucure or nanocomposites becomes intrigued in next generation energy conversion devices. Herein, we have prepared n type silicon nanowires (n-SiNWs) and water soluble Carbon Quantum Dots (CQD) through metal assisted etching and hydrothermal method respectively. The CQD possesses very low dimensions around 2–4 nm which becomes spin coated on n type silicon nanowires. The formation of silicon nanowires/ Carbon Quantum Dots heterostructures (n-SiNW/CQD) exhibits excellent photo current properties with Ilight/IDark had apparent value within the range 1.36–3.83. The heterostructure also exhibits a strong photoluminescence spectrum in blue region.

Labeling of liver cells with CdSe/ZnS quantum dot-based fluorescence probe below freezing point

In this paper, CdSe/ZnS quantum dots (QDs) with particle size of 5.5 ~ 9.3 nm were synthesized, and the fluorescence emission ranged from 545 ~ 616 nm. When the volume fraction of ethanol was 30%, the water-soluble QD dispersion system remained liquid under −20 °C freezing conditions, the fluorescence intensity increased with a decrease in temperature, and the quantum yield reached 79% at −20 °C. The endothelial cell adhesion molecule CD31 antibody (anti-CD31) was used as the primary antibody, QDs were coupled with IgG as the secondary antibody (QD-Ab), and effective labeling of hepatic sinusoid endothelial cells was achieved at −20 °C. Fluorescence imaging and flow cytometry analysis showed that the labeling efficiency was as high as 97%, indicating that QDs have an important application prospect in microscopic section tomography of the liver.