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1.
Anal Chem ; 91(23): 15308-15316, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31691562

RESUMO

Exosomes are cell-secreted membrane-coated vesicles with their sizes variable from 30 to 150 nm. So far, there is no simple, fast, and economical way to evaluate the sizes of exosomes in living systems. Here, we put forward a hypothesis in which the sphere sizes (resulting in different curvature) may affect the local mobility/viscosity of exosome membranes. Based on this hypothesis, we propose a novel method to evaluate the exosome sizes by quantifying the membrane viscosity. For this sake, we design a membrane-targeting molecular rotor with its fluorescence lifetime sensitive to viscosity and use it under a fluorescence lifetime imaging microscope (FLIM). Through a multiple-step ultrafiltration technique, we isolate three individual size distributions (10-50, 50-100, and 100-220 nm) with exosomes from HeLa and MCF-7 cell culture media and then perform the FLIM assay on the above two groups. In both cases, we indeed find a regular pattern in which the membrane viscosity reflected by lifetime decreases with exosome sizes. We then perform the assay on exosomes from cancer cells, corresponding normal tissue cells, and serum of breast cancer patients. We find that exosomes from cancer cells have a fluorescence lifetime (larger viscosity) longer than that of normal tissue cells. The average fluorescence lifetime of exosomes from a triple-negative breast cancer patient is longer (or the viscosity is larger) than that of a HER2 positive one. Therefore, our new and simple method may hold application prospects in future cancer diagnosis.

2.
J Am Chem Soc ; 141(37): 14491-14495, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31487156

RESUMO

Insufficient brightness of fluorophores poses a major bottleneck for the advancement of super-resolution microscopes. Despite being widely used, many rhodamine dyes exhibit sub-optimal brightness due to the formation of twisted intramolecular charge transfer (TICT) upon photoexcitation. Herein, we have developed a new class of quaternary piperazine-substituted rhodamines with outstanding quantum yields (Φ = 0.93) and superior brightness (ε × Φ = 8.1 × 104 L·mol-1·cm-1), by utilizing the electronic inductive effect to prevent TICT. We have also successfully deployed these rhodamines in the super-resolution imaging of the microtubules of fixed cells and of the cell membrane and lysosomes of live cells. Finally, we demonstrated that this strategy was generalizable to other families of fluorophores, resulting in substantially increased quantum yields.

3.
ACS Nano ; 13(3): 3714-3722, 2019 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-30831025

RESUMO

The efforts of detecting bioactive targets with complex, dynamic, and unknown molecular profiles have inspired the development of various biosensor platforms. Herein, we report a cell-membrane-modified field effect transistor (FET) as a function-based nanosensor for the detection and quantitative measurement of numerous toxins and biological samples. By coating carbon nanotube FETs with natural red blood cell membranes, the resulting biomimetic nanosensor can selectively interact with and absorb broad-spectrum hemolytic toxins regardless of their molecular structures. Toxin-biomembrane interactions alter the local charge distribution at the FET surface in an ultrasensitive and concentration-dependent manner, resulting in a detection limit down to the femtomolar (fM) range. Accurate and quantitative measurements are enabled via a built-in calibration mechanism of the sensor, which overcomes batch-to-batch fabrication variations, and are demonstrated using three distinct toxins and various complex bacterial supernatants. The measured signals of bacterium-secreted proteins correlate linearly with the actual bacterial numbers, making the biosensor a nontraditional approach to rapidly detecting bacterial concentrations without a need to count bacterial colonies.

4.
Chem Commun (Camb) ; 55(13): 1951-1954, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30681076

RESUMO

HoeSR, a nucleus specific probe for dSTORM super-resolution imaging of nucleus DNA in live cells, was designed by conjugating a rhodamine fluorophore and a Hoechst tag. HoeSR labels the cell nucleus in a wash-free way and emits intensive fluorescence exclusively in the nucleus. With the aid of HoeSR, nucleus nanostructures at different mitosis stages were observed through super-resolution imaging.


Assuntos
Núcleo Celular/química , Sobrevivência Celular , DNA de Neoplasias/análise , Corantes Fluorescentes/química , Imagem Óptica , Células HeLa , Humanos , Células MCF-7 , Microscopia de Fluorescência , Estrutura Molecular
5.
Anal Chem ; 90(23): 13953-13959, 2018 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-30422634

RESUMO

A change of mitochondrial temperature can be an important indicator of mitochondrial metabolism that generates considerable heat. For this reason, development of fluorescent probes to detect mitochondrial temperature has become an attractive topic. Previous efforts have successfully addressed the major issues, such as temperature sensitivity and mitochondrial targetability. However, there remains a key obstacle to practical applications. Considering the highly dynamic features of mitochondria, especially the variation of the inner-membrane potential, it is quite necessary to permanently immobilize a temperature probe in mitochondria in order to avoid unstable intracellular localization along with the changes of mitochondrial status. Herein, we report Mito-TEM, the first fixable, fluorescent molecular thermometer. Mito-TEM is based on a positively charged rhodamine B fluorophore that has the tendency of being attracted to mitochondria, which have negative potential. This fluorophore containing rotatable substituents also contributes to the temperature-responsive fluorescence property. Most importantly, a benzaldehyde is introduced in Mito-TEM as an anchoring unit that condenses with aminos of the protein and thus immobilizes the probe in mitochondria. The specific immobilization of Mito-TEM in mitochondria is unambiguously demonstrated in colocalization imaging. By using Mito-TEM, a method of visualizing and quantifying a temperature distribution through grayscale imaging of mitochondria is established and further applied to monitor the temperature changes of live cells under light heating and PMA stimulation.


Assuntos
Mitocôndrias/química , Rodaminas/análise , Temperatura Ambiente , Humanos , Células MCF-7 , Estrutura Molecular , Imagem Óptica , Fatores de Tempo , Células Tumorais Cultivadas
6.
Adv Mater ; 30(50): e1801368, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30073715

RESUMO

Soft electronics are intensively studied as the integration of electronics with dynamic nonplanar surfaces has become necessary. Here, a discussion of the strategies in materials innovation and structural design to build soft electronic devices and systems is provided. For each strategy, the presentation focuses on the fundamental materials science and mechanics, and example device applications are highlighted where possible. Finally, perspectives on the key challenges and future directions of this field are presented.

7.
Org Lett ; 20(15): 4462-4466, 2018 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-30035546

RESUMO

A fundamental, highly fluorescent, and easily accessible scaffold named BOPPY is reported. The use of hydrazine as a bridging linkage between pyrrole and N-heteroarenes enables the binding of two BF2 units to provide sufficient rigidity of the unsymmetric core skeleton. These resultant unsymmetrical BOPPYs are thus highly fluorescent in their solutions and solid powder states and exhibit high molar absorption coefficients (42200-47000 M-1 cm-1), large Stokes shifts, excellent photostability, and insensitivity to pH. More importantly, these BOPPYs showed efficient two-photon absorption in the wide spectral range of 700-900 nm, making them well suited for two-photon fluorescence microscopy imaging in living cells.

8.
Sci Adv ; 4(3): eaar3979, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29740603

RESUMO

Ultrasonic imaging has been implemented as a powerful tool for noninvasive subsurface inspections of both structural and biological media. Current ultrasound probes are rigid and bulky and cannot readily image through nonplanar three-dimensional (3D) surfaces. However, imaging through these complicated surfaces is vital because stress concentrations at geometrical discontinuities render these surfaces highly prone to defects. This study reports a stretchable ultrasound probe that can conform to and detect nonplanar complex surfaces. The probe consists of a 10 × 10 array of piezoelectric transducers that exploit an "island-bridge" layout with multilayer electrodes, encapsulated by thin and compliant silicone elastomers. The stretchable probe shows excellent electromechanical coupling, minimal cross-talk, and more than 50% stretchability. Its performance is demonstrated by reconstructing defects in 3D space with high spatial resolution through flat, concave, and convex surfaces. The results hold great implications for applications of ultrasound that require imaging through complex surfaces.


Assuntos
Imagem Tridimensional/instrumentação , Transdutores , Ultrassonografia/instrumentação , Desenho de Equipamento , Propriedades de Superfície
9.
Adv Mater ; 30(20): e1705992, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29611280

RESUMO

Organic-inorganic hybrid perovskites have demonstrated tremendous potential for the next-generation electronic and optoelectronic devices due to their remarkable carrier dynamics. Current studies are focusing on polycrystals, since controlled growth of device compatible single crystals is extremely challenging. Here, the first chemical epitaxial growth of single crystal CH3 NH3 PbBr3 with controlled locations, morphologies, and orientations, using combined strategies of advanced microfabrication, homoepitaxy, and low temperature solution method is reported. The growth is found to follow a layer-by-layer model. A light emitting diode array, with each CH3 NH3 PbBr3 crystal as a single pixel, with enhanced quantum efficiencies than its polycrystalline counterparts is demonstrated.

10.
Nat Biomed Eng ; 2(9): 687-695, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30906648

RESUMO

Continuous monitoring of the central-blood-pressure waveform from deeply embedded vessels, such as the carotid artery and jugular vein, has clinical value for the prediction of all-cause cardiovascular mortality. However, existing non-invasive approaches, including photoplethysmography and tonometry, only enable access to the superficial peripheral vasculature. Although current ultrasonic technologies allow non-invasive deep-tissue observation, unstable coupling with the tissue surface resulting from the bulkiness and rigidity of conventional ultrasound probes introduces usability constraints. Here, we describe the design and operation of an ultrasonic device that is conformal to the skin and capable of capturing blood-pressure waveforms at deeply embedded arterial and venous sites. The wearable device is ultrathin (240 µm) and stretchable (with strains up to 60%), and enables the non-invasive, continuous and accurate monitoring of cardiovascular events from multiple body locations, which should facilitate its use in a variety of clinical environments.

11.
J Breath Res ; 11(3): 036002, 2017 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-28786394

RESUMO

Real-time monitoring of breath can provide clinically relevant information about apnea syndrome and other important aspects of human physiology. Here, we introduce a flexible skin-like breath sensor developed by transfer-printing vanadium dioxide (VO2) thin films on PDMS substrates. This flexible breath sensor can conformably laminate on the skin under the nose with different curvatures and operate at different environment temperatures through day and night. Attributed to the high temperature coefficient of resistance of VO2, the enhanced breath sensing performance was demonstrated and the response time and recovery time can be as fast as 0.5 s. The excellent sensing performance and fast response time indicate that the VO2-based breath sensor is feasible in monitoring breath for prevention of apnea syndrome.


Assuntos
Testes Respiratórios/instrumentação , Óxidos/química , Compostos de Vanádio/química , Impedância Elétrica , Expiração , Humanos , Inalação , Processamento de Sinais Assistido por Computador , Temperatura Ambiente
12.
Sci Rep ; 7: 42227, 2017 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-28198812

RESUMO

Recent progresses on the Kirigami-inspired method provide a new idea to assemble three-dimensional (3D) functional structures with conventional materials by releasing the prestrained elastomeric substrates. In this paper, highly stretchable serpentine-like antenna is fabricated by a simple and quick "Cut-Transfer-Release" method for assembling stretchable 3D functional structures on an elastomeric substrate with a controlled shape. The mechanical reliability of the serpentine-like 3D stretchable antenna is evaluated by the finite element method and experiments. The antenna shows consistent radio frequency performance with center frequency at 5.6 GHz during stretching up to 200%. The 3D structure is also able to eliminate the hand effect observed commonly in the conventional antenna. This work is expected to spur the applications of novel 3D structures in the stretchable electronics.

13.
J Fluoresc ; 26(5): 1535-40, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27333797

RESUMO

Selective fluorescence turn on Zn(2+) sensor with long-wavelength emission and a large Stokes shift is highly desirable in Zn(2+) sensing area. We reported herein the synthesis and Zn(2+) recognition properties of a new thiosemicarbazone-based fluorescent sensor L. L displays high selectivity and sensitivity toward Zn(2+) over other metal ions in DMSO-H2O (1:1, v/v, HEPES 10 mM, pH = 7.4) solution with a long-wavelength emission at 572 nm and a large Stokes shift of 222 nm. Confocal fluorescence microscopy experiments demonstrate that L is cell-permeable and capable of monitoring intracellular Zn(2+). Graphical Abstract We report a new thiosemicarbazone-based fluorescent sensor (L) for selective recognition of Zn(2+) with a long wavelength emission and a large Stokes shift.


Assuntos
Fluorescência , Corantes Fluorescentes/química , Neoplasias/metabolismo , Espectrometria de Fluorescência/métodos , Tiossemicarbazonas/química , Zinco/análise , Sobrevivência Celular , Humanos , Microscopia Confocal , Neoplasias/diagnóstico por imagem , Neoplasias/patologia , Células Tumorais Cultivadas
14.
Nanoscale ; 8(18): 9592-9, 2016 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-27101973

RESUMO

Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 µW mm(-2) even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors.

15.
ACS Appl Mater Interfaces ; 7(51): 28142-7, 2015 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-26669205

RESUMO

Metal corrosion occurs anytime and anywhere in nature and the corrosion prevention has a great significance everywhere in national economic development and daily life. Here, we demonstrate a flexible hybrid nanogenerator (NG) that is capable of simultaneously or individually harvesting ambient thermal and mechanical energies and used for a self-powered cathodic protection (CP) system without using an external power source. Because of its double peculiarities of both pyroelectric and piezoelectric properties, a polarized poly(vinylidene fluoride) (PVDF) film-based NG was constructed to scavenge both thermal and mechanical energies. As a supplementary, a triboelectric NG was constructed below the pyro/piezoelectric NG to grab ambient mechanical energy. The output power of the fabricated hybrid NG can be directly used to protect the metal surface from the chemical corrosion. Our results not only verify the feasibility of self-powered CP-based NGs, but also expand potential self-powered applications.

16.
Spectrochim Acta A Mol Biomol Spectrosc ; 122: 656-60, 2014 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-24334067

RESUMO

A new 2-(2'-aminophenyl)benzimidazole (2-APBI) derivatized fluorescent sensor (L) that behaves relay recognition of Cu(2+) and S(2-) in water solution (pH 7.4) has been developed. Sensor L displays excited-state intramolecular proton transfer (ESIPT) featured two emission bands and performs highly selective and sensitive recognition to Cu(2+) through two emissions simultaneous quenching. The on-site formed L-Cu(2+) complex exhibits excellent selectivity to S(2-) with fluorescence "off-on" response via Cu(2+) displacement approach, which exerts ESIPT recovery. Thus, through modulation the ESIPT state of sensor L, relay recognition of Cu(2+) and S(2-) in water has been achieved.


Assuntos
Benzimidazóis/química , Cobre/análise , Corantes Fluorescentes/química , Sulfetos/análise , Água/análise , Ânions/análise , Cátions Bivalentes/análise , Espectrometria de Fluorescência
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