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3D CsPbX3 inorganic perovskite materials have attracted much attention in optoelectronic devices because of their strong absorbance, high photoluminescent quantum yield, tunable band gap, and narrow emission bandwidth. However, their practical usefulness is limited due to their poor stability in ambient conditions. Here, we created photoluminescent 0D Cs4PbX6 (X = Br, Br/I) suspensions in toluene by adding a small amount of water. The photoluminescent 0D Cs4PbX6 perovskite was mixed with polymethylmethacrylate (PMMA) forming 0D Cs4PbX6/PMMA composite films with higher PL, stability, transparency, and transmittance than that of the 3D CsPbX3/PMMA composite films prepared separately. Moreover, the PL intensity maintains 90% of the initial value after 30 days in water, showing excellent water stability. The flexible white-light LED device prepared by the composite films illustrated good luminescence performance with color rendering index 74.77, chromaticity coordinates (0.32, 0.33), and color temperature 6997 K.
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Inorganic perovskite cesium lead iodide nanocrystals (CsPbI3NCs) are good candidates for optoelectronic devices because of their excellent properties of remarkable luminous performance (high luminous efficiency, narrow luminous spectral line), and high photoelectric conversion efficiency by using simple preparation method. But their inherent poor stability greatly limits its practical applications. In this paper, electrospinning is used to grow fibrous membranes with embedded cesium lead iodide perovskite nanocrystals (PNCs) formedin situin a one-step process. It was found that cubicα-CsPbI3PNCs were formed in polymer fibers, showing bright and uniform fluorescence signals. Furthermore, the water wetting angles were increased by the fibrous structure enhancing the hydrophobicity and the stability of the fibrous membranes in water. The electrospun fibrous membrane containing CsPbI3was combined with another membrane containing CsPbBr3under a blue light-emitting diode (LED) to create a white LED (WLED) in air successfully with CIE coordinates (0.3020, 0.3029), and a correlated color temperature of 7527 °K, indicating high purity of WLED. Our approach provides a new way to create highly stable, photoluminescent water-resistant perovskite nanocrystalline films.
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Perovskite nanocrystals are a new type of fluorescent material with the advantages of facile preparation process, bright tunable color with high quantum yield. They are ideal candidates for optoelectronic devices such as light-emitting diode (LED) and display. However, for practical applications of iodine-based perovskite nanocrystals, the photostability remains a great challenge because of their sensitivity to environmental factors such as oxygen, humidity etc. In this paper, we improve the photostability of CsPbI3 by introducing the polymethyl methacrylate (PMMA) as a matrix to form flexible perovskite/PMMA composite films. The composite films maintain good photoluminescence quantum yield for 25 d in air and 4 d in water. Furthermore, these films are flexible and can sustain multiple bending and folding while maintaining their photoluminescence properties. This photostability against mechanical deformation allows for the development of flexible devices. As an example, flexible white light-emitting diodes (WLED) were produced with chromaticity coordination (0.31, 0.32), color temperature 6735 K and good stability over time.
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We have examined the in situ detection of a single-nucleotide KRAS mutation in urine using a (Pb(Mg1/3Nb2/3)O3)0.65(PbTiO3)0.35 (PMN-PT) piezoelectric plate sensor (PEPS) coated with a 17-nucleotide (nt) locked nucleic acid (LNA) probe DNA complementary to the KRAS mutation. To enhance the in situ mutant (MT) DNA detection specificity against the wild type (WT), detection was carried out in a flow with a flow rate of 4 mL min(-1) and at 63 °C with the PEPS vertically situated at the center of the flow in which both the temperature and the flow impingement force discriminated the wild type. Under such conditions, PEPS was shown to specifically detect KRAS MT in situ with 60 copies per mL analytical sensitivity in a background of clinically-relevant 1000-fold more WT in 30 min without DNA isolation, amplification, or labeling. For validation, this detection was followed with detection in a mixture of blue MT fluorescent reporter microspheres (FRMs) (MT FRMs) that bound to only the captured MT and orange WT FRMs that bound to only the captured WT. Microscopic examinations showed that the captured blue MT FRMs still outnumbered the orange WT FRMs by a factor of 4 to 1 even though WT was 1000-fold of MT in urine. Finally, multiplexed specific mutation detection was demonstrated using a 6-PEPS array each with a probe DNA targeting one of the 6 codon-12 KRAS mutations.
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Técnicas Biossensoriais/métodos , Mutação Puntual , Polimorfismo de Nucleotídeo Único , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/urina , Sequência de Bases , Humanos , Sondas de Oligonucleotídeos/química , Sondas de Oligonucleotídeos/genética , Oligonucleotídeos/química , Oligonucleotídeos/genéticaRESUMO
We have examined in situ detection of hepatitis B virus 1762T/1764A double mutation (HBVDM) in urine using a (Pb(Mg(1/3)Nb(2/3))O3)(0.65)(PbTiO3)(0.35) (PMN-PT) piezoelectric plate sensor (PEPS) coated with a 16-nucleotide (nt) probe DNA (pDNA) complementary to the HBVDM. The in situ mutation (MT) detection was carried out in a flow with the PEPS vertically situated at the center of the flow in a background of wild type (WT). For validation, this detection was followed by detection in the mixture of MT fluorescent reporter microspheres (FRMs) (MT FRMs) and WT FRMs that emitted different fluorescence colours and were designed to specifically bind to MT and WT, respectively. At 30 °C and 4 ml min(-1), a PEPS was shown to specifically detect HBVDM in situ with 60 copies ml(-1) analytical sensitivity in a background of clinically-relevant 250-fold more WT in 30 min without DNA isolation, amplification, or labelling as validated by the visualization of the captured MT FRMs and WT FRMs following FRM detection where the captured MT FRMs outnumbered the WT FRMs by a factor of 5 to 1.
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Técnicas Biossensoriais/métodos , Análise Mutacional de DNA/métodos , DNA Viral/urina , Vírus da Hepatite B/isolamento & purificação , Hepatite B/diagnóstico , Mutação/genética , DNA Viral/genética , Fluorescência , Genótipo , Hepatite B/genética , Hepatite B/virologia , Vírus da Hepatite B/genética , Humanos , Microesferas , Reação em Cadeia da PolimeraseRESUMO
We have examined real-time, in situ hybridization detection of target DNA (tDNA) in a buffer solution and in urine using 8 µm-thick lead magnesium niobate-lead titanate (PMN-PT) piezoelectric plate sensors (PEPSs) about 1.1-1.2 mm long and 0.45 mm wide with improved 3-mercaptopropyltrimethoxysilane (MPS) insulation and a new multiple-parabola (>50) resonance peak position fitting algorithm. With probe DNA (pDNA) immobilized on the PEPS surface and by monitoring the first width extension mode (WEM) resonance frequency shift we detected tDNA in real time at concentration as low as 1 × 10(-19) M in urine (100 zM) with a signal to noise ratio (SNR) of 13 without DNA isolation and amplification at room temperature in 30 min. The present multiple-parabola fitting algorithm increased the detection of SNR by about 10 times compared to those obtained using the raw data and by about 5 times compared to those obtained using single parabola fitting. The detection was validated by in situ follow-up detection and subsequent visualization of fluorescent reporter microspheres (FRMs) coated with reporter DNA complementary to the tDNA but different from the probe pDNA.
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Algoritmos , DNA/genética , Hibridização de Ácido Nucleico , Limite de Detecção , Razão Sinal-RuídoRESUMO
Cd0.3Pb0.7S (CdPbS) aqueous quantum dots (AQDs) made with 3-mercaptoproprionic acid (MPA) as a ligand have the advantages of emitting near-infrared light, well above 800 nm, that completely circumvents interference from tissue autofluorescence and have significant amounts of ligands for bioconjugation. However, retaining the right amount of MPA became a challenge when using CdPbS AQDs for bioimaging because retaining too much MPA could lead to significant nonspecific staining in cell imaging while insufficient MPA could cause AQDs instability in biological systems. Here we examined PEGylation (i.e. chemically linking amine-functionalized polyethylene glycol (PEG)) to modify MPA on the AQDs surface to improve AQDs stability and reduce nonspecific staining. In addition, for conjugation with antibodies, a bifunctional PEG with a carboxyl functionality was used to permit chemical linkage of a PEG to an antibody on the other end. It was found that performing PEGylation at the thiol concentration where the zeta potential becomes saturated stabilized the CdPbS AQDs suspension and reduced nonspecific binding to cells. Furthermore, with the bifunctional PEG, the CdPbS AQDs were conjugated with antibodies and the AQD-Ab conjugates were shown to stain cancer cells specifically against normal cells with a signal-to-noise ratio of 8.
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Pontos Quânticos , Cádmio , Chumbo , Diagnóstico por Imagem , Anticorpos , PolietilenoglicóisRESUMO
Detection of mutated (MT) deoxyribonucleic acid (DNA) amongst the wild type (WT) requires the probe DNA (pDNA) that is complementary to the MT to discriminate the WT by one or two nucleotide mismatches. Traditionally this is achieved by raising the temperature to above the melting temperature (Tm) of the WT (TWT) but below that of the MT (TMT). However, a raised temperature is also accompanied by a weakened binding of the MT to the pDNA which can reduce the detection sensitivity. In this study, we investigated flow as a way to enhance MT detection specificity at a lower temperature. Gold-coated glass (GCG) slides immobilized with pDNA complementary to the target MT were placed at the center of the flow cell. The detection was done by flowing MT or WT at various concentrations followed by flowing 10(5) ml(-1) fluorescent reporter microspheres (FRMs) that were 6 µm in size and coated with reporter DNA complementary to the MT or WT but different from the pDNA at various flow rates and temperatures. The detection of MT or WT was characterized by counting the FRMs captured on the GCG. Hepatitis B virus 1762/1764 double mutation (HBV DM) was the model MT and the TMT and TWT were 47 °C and 22 °C, respectively. It was shown that at room temperature, flow initially increased the binding of both the MT and WT at lower flow rates but decreased the binding at flow rates ≥4 ml min(-1) due to the increase in the flow-induced impingement force on the FRMs to overcome the binding of the MT and the WT to the GCG at higher flow rates. At ≥30 °C the decrease in binding of the WT with an increasing flow rate was more than that of the MT because 30 °C was above the TWT but still well below the TMT. As a result, the detection of MT at 30 °C with a flow rate of 4 ml min(-1) was more specific than at 35 °C without flow. These results indicate that flow can diminish WT binding at a lower temperature than without flow and allow MT detection to occur at a lower temperature with high specificity.
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DNA/análise , DNA/genética , Ambiente Controlado , Genes Reporter/genética , Microesferas , Mutação/genética , Temperatura , Vírus da Hepatite B/química , Vírus da Hepatite B/genéticaRESUMO
Quantum dots (QDs) are photoluminescent nanoparticles that can be directly or indirectly coupled with a receptor such as an antibody to specifically image a target biomolecule such as an antigen. Recent studies have shown that QDs can be directly made at room temperature and in an aqueous environment (AQDs) with 3-mercaptopropionic acid (MPA) as the capping ligand without solvent and ligand exchange typically required by QDs made by the organic solvent routes (OQDs). In this study, we have synthesized CdSe AQDs and compared their conjugation efficiency and imaging efficacy with commercial carboxylated OQDs in HT29 colon cancer cells using a primary antibody-biotinylated secondary antibody-streptavidin (SA) sandwich. We showed that the best imaging condition for AQDs occurred when one AQD was bound with 3 ± 0.3 SA with a nominal SA/AQD ratio of 4 corresponding to an SA conjugation efficiency of 75 ± 7.5%. In comparison, for commercial CdSe-ZnS OQDs to achieve 2.7 ± 0.4 bound SAs per OQD for comparable imaging efficacy a nominal SA/OQD ratio of 80 was needed corresponding to an SA conjugation efficiency of 3.4 ± 0.5% for CdSe-ZnS OQDs. The more than 10 times better SA conjugation efficiency of the CdSe AQDs as compared to that of the CdSe-ZnS OQDs was attributed to more capping molecules on the AQD surface as a result of the direct aqueous synthesis. More capping molecules on the AQD surface also allowed the SA-AQD conjugate to be stable in cell culture medium for more than three days without losing their staining capability in a flowing cell culture medium. In contrast, SA-OQD conjugates aggregated in cell culture medium and in phosphate buffer saline solution over time.
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Quantum dots (QDs) are semiconducting nanocrystals that have photoluminescent (PL) properties brighter than fluorescent molecules and do not photo-bleach, ideal for in vivo imaging of diseased tissues or monitoring of biological processes. Near-infrared (NIR) fluorescent light within the window of 700-1000 nm, which is separated from the major absorption peaks of hemoglobin and water, has the potential to be detected several millimeters under the surface with minimal interference from tissue autofluorescence. Here we report the synthesis and bioimaging demonstration of a new NIR QDs system, namely, CdPbS, made by an aqueous approach with 3-mercaptopropionic acid (MPA) as the capping molecule. The aqueous-synthesized, MPA-capped CdPbS QDs exhibited an NIR emission in the range of 800-950 nm with x(i) ≥ 0.3, where x(i) denotes the initial Pb molar fraction during the synthesis. Optimal PL performance of the CdPbS QDs occurred at x(i) = 0.7, which was about 4 nm in size as determined by transmission electron microscopy, had a rock salt structure and a quantum yield of 12%. Imaging of CdPbS QDs was tested in membrane staining and transfection studies. Cells transfected with CdPbS QDs were shown to be visible underneath a slab of chicken muscle tissue of up to 0.7 mm in thickness without the use of multiple-photon microscopy.
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Compostos de Cádmio/química , Chumbo/química , Microscopia/métodos , Pontos Quânticos , Compostos de Selênio/química , Água/química , Meios de Contraste , Raios Infravermelhos , Teste de MateriaisRESUMO
A new type of pyroelectric field effect transistor based on a composite consisting of single zinc oxide nanowire and lead zirconate titanate (ZnO NW-PZT) has been developed. Under infrared (IR) laser illumination, the transconductance of the ZnO NW can be modulated by optothermal gating. The drain current can be increased or decreased by IR illumination depending on the polarization orientation of the Pb(Zr(0.3)Ti(0.7))O(3) (PZT) substrate. Furthermore, by combining the photocurrent behavior in the UV range and the optothermal gating effect in the IR range, the wide spectrum of response of current by light offers a variety of opportunities for nanoscale optoelectronic devices.
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Rapid and sensitive detection of serum tumor biomarkers are needed to monitor cancer patients for disease progression. Highly sensitive piezoelectric microcantilever sensors (PEMS) offer an attractive tool for biomarker detection; however, their utility in the complex environment encountered in serum has yet to be determined. As a proof of concept, we have functionalized PEMS with antibodies that specifically bind to HER2, a biomarker (antigen) that is commonly overexpressed in the blood of breast cancer patients. The function and sensitivity of these anti-HER2 PEMS biosensors was initially assessed using recombinant HER2 spiked into human serum. Their ability to detect native HER2 present in the serum of breast cancer patients was then determined. We have found that the anti-HER2 PEMS were able to accurately detect both recombinant and naturally occurring HER2 at clinically relevant levels (>2 ng/mL). This indicates that PEMS-based biosensors provide a potentially effective tool for biomarker detection.
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Análise Química do Sangue/métodos , Neoplasias da Mama/sangue , Eletricidade , Espaço Extracelular , Receptor ErbB-2/sangue , Receptor ErbB-2/química , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais Humanizados , Biomarcadores Tumorais/sangue , Biomarcadores Tumorais/química , Estudos de Casos e Controles , Humanos , Masculino , Estrutura Terciária de Proteína , Receptor ErbB-2/imunologia , TrastuzumabRESUMO
We have investigated real-time, label-free, in-situ detection of human epidermal growth factor receptor 2 (Her2) in diluted serum using the first longitudinal extension mode of a lead zirconate-lead titanate (PZT)/glass piezoelectric microcantilever sensor (PEMS) with H3 single-chain variable fragment (scFv) immobilized on the 3-mercaptopropyltrimethoxysilane (MPS) insulation layer of the PEMS surface. We showed that with the longitudinal extension mode, the PZT/glass PEMS consisting of a 1 mm long and 127 µm thick PZT layer bonded with a 75 µm thick glass layer with a 1.8 mm long glass tip could detect Her2 at a concentration of 6-60 ng/ml (or 0.06-0.6 nM) in diluted human serum, about 100 times lower than the concentration limit obtained using the lower-frequency flexural mode of a similar PZT/glass PEMS. We further showed that with the longitudinal mode, the PZT/glass PEMS determined the equilibrium H3-Her2 dissociation constant K(d) to be 3.3±0.3 × 10(-8) M consistent with the value, 3.2±0.28 ×10(-8) M deduced by the surface plasmon resonance method (BIAcore).
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Cytotoxicity tests of zinc sulfide (ZnS) and cadmium sulfide (CdS) quantum dots (QDs) synthesized via all-aqueous process with various surface conditions were carried out with human endothelial cells (EA hy926) using two independent viability assays, i.e., by cell counting following Trypan blue staining and by measuring Alamar Blue (AB) fluorescence. The ZnS QDs with all four distinct types of surface conditions were nontoxic at both 1 microM and 10 microM concentrations for at least 6 days. On the other hand, the CdS QDs were nontoxic only at 1 microM, and showed significant cytotoxicity at 10 microM after 3 days in the cell counting assay and after 4 days in the AB fluorescence assay. The CdS QDs with (3-mercaptopropyl)trimethoxysilane (MPS)-replacement plus silica capping were less cytotoxic than those with 3-mercaptopropionic acid (MPA) capping and those with MPS-replacement capping. Comparing the results of ZnS and CdS QDs with the same particle size, surface condition and concentration, it is indicated that the cytotoxicity of CdS QDs and the lack of it in ZnS QDs were probably due to the presence and absence of the toxic Cd element, respectively. The nontoxicity of the aqueous ZnS QDs makes them favorable for in vivo imaging applications.
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Compostos de Cádmio/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/fisiologia , Nanoestruturas/administração & dosagem , Pontos Quânticos , Compostos de Selênio/farmacologia , Sulfetos/farmacologia , Compostos de Zinco/farmacologia , Compostos de Cádmio/química , Linhagem Celular , Células Endoteliais/citologia , Humanos , Teste de Materiais , Nanoestruturas/química , Compostos de Selênio/química , Solubilidade , Sulfetos/química , Testes de Toxicidade , Água/química , Compostos de Zinco/químicaRESUMO
Piezoelectric microcantilever sensors (PEMS) can be sensitive tools for the detection of proteins and cells in biological fluids. However, currently available PEMS can only be used a single time or must be completely stripped and refunctionalized prior to subsequent uses. Here we report the successful use of an alternative regeneration protocol employing high salt concentrations to remove the target, leaving the functional probe immobilized on the microcantilever surface. Our model system employed the extracellular domain (ECD) of recombinant human Epidermal Growth Factor Receptor (EGFR) as the probe and anti-human EGFR polyclonal antibodies as the target. We report that high concentrations of MgCl2 dissociated polyclonal antibodies specifically bound to EGFR ECD immobilized on the sensor surface without affecting its bioactivity. This simple regeneration protocol both minimized the time required to re-conjugate the probe and preserved the density of probe immobilized on PEMS surface, yielding identical biosensor sensitivity over a series of assays.
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Técnicas Biossensoriais/instrumentação , Anticorpos/química , Antígenos/química , Biomarcadores/análise , Técnicas Biossensoriais/métodos , Desenho de Equipamento , HumanosRESUMO
Cesium lead halide perovskite nanocrystals have a narrow emission peak tunable in the visible wavelength range with a high quantum yield. They hold great potential for optoelectronic applications such as light-emitting diodes or electronic displays. However, cesium lead iodide (CsPbI3) is not stable under ambient conditions, limiting its applications. Here, we use a solution surface treatment approach to improve the photostability of CsPbI3 suspensions in toluene. When a CsPbBr3 precursor is used via the method of heterogeneous surface treatment, the photoluminescence (PL) intensity is enhanced but the PL only lasts 2 days. In contrast, when a CsPbI3 precursor is used via the method of homogeneous surface treatment, not only the PL intensity of CsPbI3 suspensions is enhanced but also the stability with the PL lasts for 11 days. It is likely that a better protection on the core CsPbI3 by itself can be achieved because of better matching of the material structure and surface chemistry.
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We have examined the relative longitudinal flexural resonance frequency shift of a PMN-PT/tin PEMS with a DC bias electric field, E, in humidity detection. We showed that the relative resonance frequency shift could be enhanced by applying an E to the PMN-PT layer during detection. A maximum enhancement of more than three times in resonance frequency shift was observed at E = -6 kV/cm as compared to the resonance frequency shift without a bias field. The maximal relative resonance frequency shift at E = -6 kV/cm was about 1000 times larger than could be accounted for by mass loading alone.
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Mammography is the only Food and Drug Administration approved breast cancer screening method. The drawback of the tumor image in a mammogram is the lack of tumor depth information as it is only a 2-dimensional projection of a 3-dimensional (3D) tumor. In this work, we investigated 3D tumor imaging by assessing tumor depth information using a set of piezoelectric fingers (PEFs) with different probe sizes which were known to be capable of eliciting tissue elastic responses to different depths and tested it on model tumor tissues consisted of gelatin with suspended clay inclusions. The locations of the top and bottom surfaces of an inclusion were resolved by solving a simple spring model using the elastic measurements of the PEFs of different probe sizes as the input. The lateral sizes of an inclusion were determined as the full width at half maximum of the Gaussian fit to the measured lateral tumor elastic modulus profile. The obtained lateral inclusion sizes were in close agreement with the actual values, and the deduced depth profiles of an inclusion also agreed with the actual depth profiles so long as the bottom surface of the inclusion was within the depth sensitivity of the PEF with the largest probe size. This work offers a simple non-invasive method to predict the extent of a tumor in all 3 dimensions. The method is also non-radioactive.
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Neoplasias da Mama/diagnóstico por imagem , Eletricidade , Imageamento Tridimensional/instrumentação , Módulo de ElasticidadeRESUMO
Dual-functional devices that can simultaneously detect light and emit light have a tremendous appeal for multiple applications, including displays, sensors, defense, and high-speed optical communication. Despite the tremendous efforts of scientists, the progress of integration of a phototransistor, where the built-in electric field separates the photogenerated excitons, and a light-emitting diode, where the radiative recombination can be enhanced by band offset, into a single device remains a challenge. Combining the superior properties of perovskite quantum dots (PQDs) and graphene, here we report a light-emissive, ultrasensitive, ultrafast, and broadband vertical phototransistor that can simultaneously act as an efficient photodetector and light emitter within a single device. The estimated value of the external quantum efficiency of the vertical phototransistor is â¼1.2 × 1010% with a photoresponsivity of >109 A W-1 and a response time of <50 µs, which exceed all the presently reported vertical phototransistor devices. We also demonstrate that the modulation of the Dirac point of graphene efficiently tunes both amplitude and polarity of the photocurrent. The device exhibits a green emission having a quantum efficiency of 5.6%. The moisture-insensitive and environmentally stable, light-emissive, ultrafast, and ultrasensitive broadband phototransistor creates a useful route for dual-functional optoelectronic devices.
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Current genetic detection methods require gene isolation, gene amplification and detection with a fluorescent-tagged probe. They typically require sophisticated equipment and expensive fluorescent probes, rendering them not widely available for rapid acute infection diagnoses at the point of care to ensure timely treatment of the diseases. Here we report a rapid genetic detection method that can detect the bacterial gene directly from patient stools using a piezoelectric plate sensor (PEPS) in conjunction with a continuous flow system with two temperature zones. With stools spiked with sodium dodecyl sulfate (SDS) in situ bacteria lysing and DNA denaturation occurred in the high-temperature zone whereas in situ specific detection of the denatured DNA by the PEPS occurred in the lower-temperature zone. The outcome was a rapid genetic detection method that directly detected bacterial genes from stool in <â¯40â¯min without the need of gene isolation, gene amplification, or expensive fluorescent tag but with polymerase chain reaction (PCR) sensitivity. In 40 blinded patient stools, it detected the toxin B gene of Clostridium difficile with 95% sensitivity and 95% specificity. The all-electrical, label-free nature of the detection further supports its potential as a low-cost genetic test that can be used at the point of care.