Near-infrared Quantum Dots Research Articles

Surface plasmon resonance enhancement of photoluminescence intensity and bioimaging application of gold nanorod@CdSe/ZnS quantum dots

Biological applications of core/shell near-infrared quantum dots (QDs) have attracted broad interest due to their unique optical and chemical properties. Additionally, the use of multifunctional nanomaterials with near-infrared QDs and plasmonic functional nanoparticles are promising for applications in electronics, bioimaging, energy, and environmental-related studies. In this work, we experimentally demonstrate how to construct a multifunctional nanoparticle comprised of CdSe/ZnS QDs and gold nanorods (GNRs) where the GNRs were applied to enhance the photoluminescence (PL) of the CdSe/ZnS QDs. In particular, we have obtained the scattering PL spectrum of a single CdSe/ZnS QD and GNR@CdSe/ZnS nanoparticle and comparison results show that the CdSe/ZnS QDs have an apparent PL enhancement of four-times after binding with GNRs. In addition, in vitro experimental results show that the biostability of the GNR@CdSe/ZnS nanoparticles can be improved by using folic acid. A bioimaging study has also been performed where GNR@CdSe/ZnS nanoparticles were used as an optical process for MCF-7 breast cancer cells.

Molecular interaction of silicon quantum dot micelles with plasma proteins: hemoglobin and thrombin.

Protein conformational changes are associated with potential cytotoxicity upon interaction with small molecules or nanomaterials. Protein misfolding leads to protein-mediated diseases; thus, it is important to study the conformational changes in proteins using nanoparticles as drug carriers. In this study, the conformational changes in hemoglobin and thrombin were observed using fluorescence spectroscopy, circular dichroism spectroscopy and molecular modelling studies after interaction with non-toxic, water-soluble near-infrared silicon quantum dot micelles. The molecular docking results indicated that the binding affinities of hemoglobin and thrombin with Si QD micelles are good. In addition, molecular dynamics simulations were performed to obtain more detailed information.

近红外PbS量子点掺杂光子晶体光纤的光传输特性

近红外PbS量子点掺杂光子晶体光纤的光传输特性

Assembly-enhanced fluorescence from metal nanoclusters and quantum dots for highly sensitive biosensing

Fluorescent nanoparticles exhibit unique optical properties for applications in imaging and sensing. Herein, the enhancement of luminescence emission from self-assembled nanoparticles including gold nanoclusters, cadmium sulphide and near-infrared silver selenide quantum dots are reported. Addition of zinc and pyrophosphate ions induces assembly and disassembly of the particle aggregates and the corresponding intensified and recovery of fluorescence intensity, respectively. The enhancement is due to assembly-enhanced emission of metal nanoclusters and passivation of the surface trap states of quantum dots. With the hydrolysis of pyrophosphate catalyzed by alkaline phosphatase, the released zinc ions from pyrophosphate-zinc ion complexes mediate nanoparticle assembly and lead to luminescence regeneration. The assembly-induced fluorescence enhancement can be applied for sensitive assay of alkaline phosphatase with a detection limit of 3.4 pM in a continuous and real-time way. This method is capable of screening enzyme inhibitor and analyzing biological samples.

Cathodic Quantum Dot Facilitated Electrochemiluminescent Detection in Blood.

The expansion of electrochemical sensors to biomedical applications at point of care requires these sensors to undergo analysis without any pretreatment or extraction. This poses a major challenge for all electrochemical sensors including electrochemiluminescent (ECL)-based sensors. ECL offers many advantages for biomedical applications; however, obtaining results from complex matrixes has proven to be a large hurdle for the application of ECL sensors within this field. This work demonstrates the potential of cathodic ECL to detect and quantify homocysteine (Hcy) with a 0.1 nM limit of detection, which is associated with hyperhomocysteinemia, in blood. This near-infrared quantum dot (NIR QD)-based ECL sensor displays good linearity allowing for rapid detection and providing a basis for exploitation of ECL-based sensors for biomedical diagnostics utilizing Hcy as a model cathodic coreactant. This work will lay the foundations for future developments in biosensing and imaging fields and stands as an initial proof of concept for the utilization of cathodic ECL technologies for biomedical applications once the limits of detection within clinically relevant levels has been achieved. This work illustrates the potential of cathodic ECL sensors, using Hcy as a model complex, for the detection of biomolecules.

Abstract LB-330: Investigating how extracellular signals contribute to single cancer cell heterogeneity using near-infrared quantum dots

Abstract Cancer cells heterogeneity presents a major roadblock in clinical diagnostics and therapy. Investigations of tumor cell heterogeneity using single-cell analytical techniques have revealed not only the presence of multiple clonal subpopulations but also phenotypic variability among genetically identical cells. This heterogeneity plays a critical role in therapeutics, as population extrema, rather than cells near the ensemble mean, can dominate pathogenesis as well as drug resistance. To characterize single cell heterogeneity, multiple techniques quantifying single-cell gene expression have been developed. However, there's a lack of experimental techniques to measure how cellular decision-making processes underlying population variability derive from extracellular biochemical input signals, such as peptide growth factors, which cannot be measured at the single-cell level. Here, to digitally count growth factors in single cells, we develop a novel method combining fluorescent quantum dots and calibrated three-dimensional deconvolution microscopy (QDC-3DM). Using quantum dots with near-infrared emission to overcome intrinsic cellular autofluorescence, we were able to detect and accurately count individual quantum dots conjugated to epidermal growth factor (EGF) using their fluorescent intensities. Analyzing triple-negative breast cancer cells (MDA-MB-231) with QDC-3DM, we observed that single-cell heterogeneity in growth factor stimulation led to heterogeneity in receptor activation. When treating cells with increasing concentration of phamarcological inhibitor blocking receptor activation, we observed a proportional increase in receptor activation heterogeneity. Together, our results indicate that external stimulation contributes to signaling variation and drug response variation at the single-cell level. We anticipate that QDC-3DM can be applied to any peptidic ligands to study how extracellular signaling stimulation contributes to phenotypic variability to provide new insight into cancer cell heterogeneity that plays a critical role in therapeutic resistance. Citation Format: Phuong Le, Brian C. Baculis, Hee Jung Chung, Kristpher Kilian, Andrew M. Smith. Investigating how extracellular signals contribute to single cancer cell heterogeneity using near-infrared quantum dots [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-330.

A Novel Fluorescent Nanoparticle for Sensitive Detection of Cry1Ab Protein In Vitro and In Vivo

Here, we report the synthesis and characterization of CoFe2O4 doping Ag2S dendrimer-modified nanoparticles (CoFe2O4-Ag2S DMNs) in Cry1Ab protein detection and imaging. The near-infrared Ag2S quantum dots were first prepared by using the thermal decomposition method, followed by modification of the water-soluble quantum dots using the method of solvent evaporation and ligand exchange, and finally the fluorescent magnetic bifunctional nanoparticles were obtained by binding with CoFe2O4. As-prepared CoFe2O4-Ag2S DMNs were characterized by fluorescence (FL) spectroscopy and transmission electron microscopy (TEM). Results showed that Ag2S DMNs could sensitively detect Cry1Ab both in vitro and in vivo. In vitro, the enhanced FL intensity as a function of the concentration is notably consistent with the Langmuir binding isotherm equation in the range of 0-200ng/mL of Cry1Ab proteins. The detection limit of this method was found to be 0.2ng/mL. Meanwhile, the fluorescence wavelength was extended to the second near-infrared range (NIR-II, 1.0~1.4μm), which enables in vivo imaging. This study highlights the importance of NIR QDs doping magnetic materials as a new method to trace Bacillus thuringiensis (Bt) in insects and their potential applications in in vivo NIR tissue imaging.

Near-infrared MnCuInS/ZnS@BSA and urchin-like Au nanoparticle as a novel donor-acceptor pair for enhanced FRET biosensing

An enhanced near-infrared (NIR) FRET biosensing system based on the novel donor-acceptor pair (MnCuInS/ZnS@BSA and urchin-like Au NPs) was developed for the sensitive detection of HER2 protein. In this strategy, MnCuInS/ZnS quantum dots (QDs) were chosen due to their NIR emission, high quantum efficiency, and low toxicity. Amounts of MnCuInS/ZnS QDs were encapsulated in BSA to form MnCuInS/ZnS@BSA nanoparticles, which can easily transfer MnCuInS/ZnS QDs from organic phase into aqueous solution, and the formed nanoparticles were applied as the energy donor which significantly enhanced the fluorescence intensity. As for the energy acceptor, urchin-like Au nanoparticles (Au NPs) with novel structure, good stability and excellent quenching ability towards NIR fluorescence were selected. Thus, the NIR MnCuInS/ZnS@BSA and urchin-like Au NPs were designed as a novel donor-acceptor pair for FRET assay. By combining the optical advantages of NIR QDs encapsulated BSA nanoparticles with the excellent fluorescence quenching ability of urchin-like Au NPs, the proposed FRET-based biosensor realized enhanced FRET effect for highly sensitive detection of HER2 in human serum samples. A wide detection range (2–100 ng mL−1) and a low detection limit (1 ng mL−1) were obtained. This sensing system can decrease the interference of other biomolecules in NIR region, can be applied to other biomarker determination in vitro, and also shows great potential for in vivo diagnosis.

Fine-tuning of Silica Coating Procedure for Preparation of Biocompatible and Bright Pbs/Sio2 Qds

.

Facile Synthesis of Near-Infrared Emissive CdS Quantum Dots for Live Cells Imaging.

CdS quantum dots (QDs) have attracted extensive attention owing to their great potential in optoelectronic nanodevices and biosensors. But their poor water solubility and high cytotoxicity restrict their practical application in live cell imaging. In addition, CdS QDs usually emit blue or green fluorescence, which also have some limitations for cell imaging due to the "water window" effect. In this study, we report a novel strategy to directly synthesize water-soluble and low-cytotoxic CdS QDs with near infrared (NIR) fluorescence through confinement into BSA templates with the mediation of L-cysteine (Cys). The obtained CdS QDs emit NIR fluorescence at 730 nm when exited by 468 nm excitation light, and show good water solubility and low cell cytotoxicity, which can be directly used for live RAW cell imaging. In addition, the effects of the type of amino acids for mediations, and the ratio of both Cys/Cd and Cd/BSA on the fluorescence properties of CdS QDs have also been investigated comprehensively. The mediation of L-cysteine plays a critical role on the formation of CdS QDs emitting NIR fluorescence.

Recombinant Protein (Luciferase-IgG Binding Domain) Conjugated Quantum Dots for BRET-Coupled Near-Infrared Imaging of Epidermal Growth Factor Receptors.

For the highly sensitive near-infrared (NIR) optical detection of epidermal growth factor receptors (EGFRs) expressed on cancer cells, bioluminescence resonance energy transfer (BRET) coupled NIR quantum dots (QDs) are prepared by direct conjugation of his-tagged Renilla luciferase (RLuc) recombinant protein (HisRLuc·GB1) to glutathione-coated CdSeTe/CdS QDs (GSH-QDs). The recombinant protein has two functional groups consisting of a luciferase enzyme and an immunoglobulin binding domain (GB1) of protein G. Recombinant protein (HisRLuc·GB1) conjugated QDs (GB1·RLuc-QDs) show BRET-coupled NIR emission, which results from energy transfer from luciferin to QDs with a high BRET efficiency of ca. 50%. Since the GB1·RLuc-QDs have the GB1 domain at their surface, the QDs have an ability to bind the Fc moiety of immunoglobulin G (IgG). The resulting IgG bound QDs can be used as a molecular imaging probe with NIR fluorescence and BRET-coupled NIR emission. For NIR optical detection of EGFRs on cancer cells, we conjugated anti-EGFR monoclonal antibody to the GB1·RLuc-QDs. Herein, we show that the detection sensitivity of EGFRs by BRET-coupled NIR emission of GB1·RLuc-QDs is at least three times higher than that of the NIR fluorescence of the QDs. The conjugates between anti-EGFR antibody and GB1·RLuc-QDs make it possible to perform BRET-based highly sensitive NIR imaging of EGFRs in living cells.

Near-infrared quantum dots labelled with a tumor selective tetrabranched peptide for in vivo imaging

BackgroundNear-infrared quantum dots (NIR QDs) are a new class of fluorescent labels with excellent bioimaging features, such as high fluorescence intensity, good fluorescence stability, sufficient electron density, and strong tissue-penetrating ability. For all such features, NIR QDs have great potential for early cancer diagnosis, in vivo tumor imaging and high resolution electron microscopy studies on cancer cells.ResultsIn the present study we constructed NIR QDs functionalized with the NT4 cancer-selective tetrabranched peptides (NT4-QDs). We observed specific uptake of NT4-QDs in human cancer cells in in vitro experiments and a much higher selective accumulation and retention of targeted QDs at the tumor site, compared to not targeted QDs, in a colon cancer mouse model.ConclusionsNIR QDs labelled with the tetrabranched NT4 peptide have very promising performance for selective addressing of tumor cells in vitro and in vivo, proving rising features of NT4-QDs as theranostics.

Gd-DTPA-coupled Ag2Se quantum dots for dual-modality magnetic resonance imaging and fluorescence imaging in the second near-infrared window

Near-infrared (NIR) fluorescent quantum dots (QDs) are ideal platforms to fabricate multifunctional contrast agents for multimodal imaging. Herein, second near-infrared window fluorescent (NIR-II) Ag2Se QDs were coupled with gadopentetate dimeglumine injection (Gd-DTPA) for dual-modality T1-weighted magnetic resonance (MR) imaging and fluorescence imaging. In vitro experiments suggested that the prepared Ag2Se-Gd QDs exhibit low cytotoxicity, remarkable T1-weighted MR imaging, and fluorescence imaging contrast properties. In vivo experiment results showed that Ag2Se-Gd QDs were the preferred contrast agents for dual-modality T1-weighted MR imaging and fluorescence imaging with high spatial resolution. Moreover, excellent temporal resolution and high tissue penetration depth were also achieved by fluorescence imaging. These results indicate the potential of Ag2Se-Gd QDs as multifunctional contrast agents for multimodal imaging in clinical diagnosis and research.

Self-assembled dual fluorescence nanoparticles for CD44-targeted delivery of anti-miR-27a in liver cancer theranostics.

Despite the vital role miRNA-27a plays in driving the development and progress of liver cancer, miRNA-based inhibition therapy is hampered due to its undesired degradation and off-target effects. Herein, a multifunctional nanoparticle for noninvasive tracking of targeted delivery of anti-miR-27a oligonucleotides against liver cancer was constructed.Methods: Dual-fluorescent conjugates (QD-HA-PEI) were first fabricated through crosslinking hyaluronic acid (HA), polyethyleneimine (PEI) and near-infrared (NIR) fluorescent quantum dots (QDs) via a facile one-pot approach. Antisense oligonucleotide was then encapsulated by QD-HA-PEI to form anti-miR-27a/QD-HA-PEI via electrostatic interactions. Targeting, biodistribution, bioimaging, in vitro cytotoxicity and in vivo anti-tumor effects were evaluated and the underlying mechanism was studied.Results: The NIR fluorescence of anti-miR-27a/QD-HA-PEI could be employed to monitor CD44 receptor-targeted cellular uptake and tumor accumulation. Importantly, the intrinsic fluorescence of anti-miR-27a/QD-HA-PEI remained in the “ON” state in extracellular or blood environment, but switched to the “OFF” state in the intracellular environment, indicating pH-responsive oligonucleotide release. Furthermore, anti-miR-27a/QD-HA-PEI exhibited effective and selective anti-cancer effects in vitro and in vivo with fewer side effects via the direct down-regulation of oncogenic transcription factors FOXO1 and PPAR-γ.Conclusion: Our findings validate the dual-fluorescent nanoparticles as delivery vectors of therapeutic miRNA, capable of simultaneous tumor imaging and tracking of miRNA-based modulation therapy, thereby providing an efficient and safe approach for liver cancer theranostics.

Near-Infrared Quantum Dot Emission Enhanced by Stabilized Self-Assembled J-Aggregate Antennas.

Enhancing photoluminescent emission (PL) in the near-infrared-infrared (NIR-IR) spectral region has broad applications from solar energy conversion to biological imaging. We show that self-assembled molecular dye J-aggregates (light-harvesting nanotubes, LHNs) can increase the PL emission of NIR PbS quantum dots (QDs) in both liquid and solid media more than 8-fold, promoted primarily by a long-range antenna effect and efficient Förster resonance energy transfer (FRET) from donor to acceptor. To create this composite material and preserve the optical properties of the nanocrystals, we performed an in situ ligand substitution followed by a functionalization reaction using click-chemistry. This resulted in PbS QDs soluble in an aqueous environment compatible with the molecular J-aggregates (LHNs). Theoretical and experimental results demonstrate that long-range diffusive exciton transport in LHNs enables efficient energy transfer to low concentrations of QDs despite there being no direct binding between molecular donors and QD acceptors. This suggests a broad application space for mixed light harvesting and photophysically active nanocomposite materials based on self-assembling molecular aggregates.

Red and Near-Infrared III-Nitride Quantum Dot Lasers

InGaN/GaN self-organized quantum dots and similar dots in GaN nanowires are formed by strain relaxation and the luminescence from these nanostructures extends to longer wavelengths than generally obtained with quantum wells. We have exploited this advantage by incorporating these nanostructures in the gain region of edge-emitting diode lasers. Here, we describe the characteristics of 650 nm self-organized quantum dot lasers epitaxially grown on GaN and 1.3 μm dot-in-nanowire array lasers grown on (001) Si by molecular beam epitaxy. The devices are characterized by relatively low threshold currents, excellent temperature stability (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> > 200 K), and differential gain ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-16</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The highest measured small-signal modulation bandwidth of the dot-in-nanowire laser is 3.3 GHz. The experiments have been complemented by theoretical modeling of the self-organized quantum dots and lasers made with them. These new classes of devices open up new opportunities in applications such as displays, optical data storage, heads-up displays in automobiles, plastic fiber communication, and silicon photonics.

Mitochondrial specific photodynamic therapy by rare-earth nanoparticles mediated near-infrared graphene quantum dots

Photodynamic therapy (PDT) has been proposed in cancer treatment for decades, but its clinical translation is significantly impeded by the low yield of ROS, poor tissue penetration depth of most current photosensitizers, and short lifetime of ROS. These limitations directly affect the therapeutic effect of PDT in cancer therapy. Here we proposed a new strategy by collaboratively integrating rare-earth doped upconversion nanoparticles (UCNP) with graphene quantum dot (GQD) for highly efficacious PDT, based on the merits of UCNP, which can emit UV–vis light under near-infrared light (NIR) excitation, and GQD, which can produce 1O2 efficiently. For GQD-decorated UCNP nanoparticles (UCNP-GQD), the emission light from UCNP can further excite GQD with prominent 1O2 generation for NIR-triggered PDT. Furthermore, a hydrophilic rhodamine derivative, TRITC, is covalently tethered to afford the resultant UCNP-GQD/TRITC, possessing distinct mitochondrial targeting property. Thus mitochondrial specific PDT with in-situ1O2 burst in mitochondria induces sharp decrease of mitochondrial membrane potential, which initiates the tumor cell apoptosis irreversibly. Importantly, in vivo experiments demonstrate the tumor inhibition of mitochondrial targeting UCNP-GQD/TRITC with improved therapeutic efficiency compared with non-targeting UCNP-GQD. The proposed strategy highlights the advantages of precision organelles-specific PDT in cancer therapy.

Folic acid-conjugated cationic Ag2S quantum dots for optical imaging and selective doxorubicin delivery to HeLa cells.

We aim to develop folic acid (FA)-conjugated cationic Ag2S near-infrared quantum dots (NIRQDs) for the delivery of doxorubicin (DOX) selectively to folate receptor (FR)-positive cancer cells to achieve enhanced drug efficacy and optical tracking in the NIR region. Cationic Ag2S NIRQDs were decorated with FA using a PEG bridge and loaded with DOX. In vitro studies were performed on FR-positive human cervical carcinoma cells and FR-negative A549 cells. Significantly higher uptake of DOX by human cervical carcinoma cells cells and a greater therapeutic effect along with a strong intracellular optical signal were obtained with DOX-loaded FA-conjugated Ag2S NIRQDs. These Ag2S NIRQDs are promising theranostic nanoparticles for receptor-mediated delivery of DOX with enhanced drug efficacy combined with optical imaging.

In vivo cation exchange in quantum dots for tumor-specific imaging

In vivo tumor imaging with nanoprobes suffers from poor tumor specificity. Here, we introduce a nanosystem, which allows selective background quenching to gain exceptionally tumor-specific signals. The system uses near-infrared quantum dots and a membrane-impermeable etchant, which serves as a cation donor. The etchant rapidly quenches the quantum dots through cation exchange (ionic etching), and facilitates renal clearance of metal ions released from the quantum dots. The quantum dots are intravenously delivered into orthotopic breast and pancreas tumors in mice by using the tumor-penetrating iRGD peptide. Subsequent etching quenches excess quantum dots, leaving a highly tumor-specific signal provided by the intact quantum dots remaining in the extravascular tumor cells and fibroblasts. No toxicity is noted. The system also facilitates the detection of peritoneal tumors with high specificity upon intraperitoneal tumor targeting and selective etching of excess untargeted quantum dots. In vivo cation exchange may be a promising strategy to enhance specificity of tumor imaging.

Charge-Neutral, Stable, Non-Cytotoxic, Near-Infrared SnS Aqueous Quantum Dots for High Signal-to-Noise-Ratio Biomedical Imaging.

We have synthesized charge-neutral, stable, non-cytotoxic, bright, near-infrared (NIR) SnS quantum dots (QDs) by first making Cysteamine-capped SnS QDs in glycerol under acidic conditions followed by lengthening the capping molecule with peptide bonds by reacting the capping molecules with glycine and subsequent heat treatment at 200°C for 4 hours. The obtained stable SnS QDs exhibited a band gap of 1.5 eV and a strong, narrow NIR emission peak at 830 nm with a quantum yield of 4.6%. The suspension could be stable for more than 1 month without aggregation or emission decay. The positively charged SnS QDs were further neutralized by 3-mercaptoproprionic acid (MPA) through electrostatic attraction. The MPA neutralized SnS QDs were shown to be non-cytotoxic at concentrations 6 times the typical QDs concentration for immunostaining. Low-noise, optimal NIR immunofluorescent imaging of vascular endothelial growth factor (VEGF) on 3T3 cells and Tn antigen on HT29 cells was achieved by using streptavidin (SA)-linked MPA-neutralized SnS QDs with a SA:QD molar ratio of 22:1 to bind to biotinylated secondary antibody bound on the primary antibody that was bound on the targeted antigen on the cell membrane with a high signal-to noise ratio (SNR) of 35.