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2.
Nanoscale ; 11(41): 19291-19296, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31560008

RESUMO

The integration of large-scale 2D bimetallic Ag/Au nanodisk arrays with gold nanoparticles is developed for sensing DNA conformation with the assistance of 3D finite-difference time-domain simulation. The optimized system comprising Ag/Au nanodisk arrays and gold nanoparticles offers a more than 6-fold enhancement in surface plasmon resonance shift, enabling the feasibility for sensitive DNA detection with a detection limit down to 100 femtomolar. Importantly, owing to the distance-dependent nature of the surface plasmon signal, sensitive differentiation of DNA conformations can be achieved with a conventional optical measurement. This platform could provide new exciting capabilities for a reliable, reproducible, and label-free assay analysis for investigating the conformations of DNA and other biological molecules.

3.
Small ; 15(40): e1804404, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31489785

RESUMO

2D materials, namely thin layers of layered materials, are attracting much attention because of their unique electronic, optical, thermal, and catalytic properties for wide applications. To advance both the fundamental studies and further practical applications, the scalable and controlled synthesis of large-sized 2D materials is desired, while there still lacks ideal approaches. Alternatively, the chemical vapor transport reaction is an old but powerful technique, and is recently adopted for synthesizing 2D materials, producing bulk crystals of layered materials or corresponding 2D films. Herein, recent advancements in synthesizing both bulk layered and 2D materials by chemical vapor transport reactions are summarized. Beginning with a brief introduction of the fundamentals of chemical vapor transport reactions, chemical vapor transport-based syntheses of bulk layered and 2D materials, mainly exampled by transition metal dichalcogenides and black phosphorus, are reviewed. Particular attention is paid to important factors that can influence the reactions and the growth mechanisms of black phosphorus. Finally, perspectives about the chemical vapor transport-based synthesis of 2D materials are discussed, intending to redraw attentions on chemical vapor transport reactions.

4.
Nanoscale ; 11(24): 11902-11909, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31184692

RESUMO

Cu nanowires, as promising candidates in many fields because of their merits, are commonly prepared by the solution phase based synthesis which is a simple and scalable method. However, precise control of the morphology, particularly surface roughness, of Cu nanowires is still challenging; and moreover, detailed formation mechanisms of Cu nanowires, in solution phase based synthesis, are still unclear. We here show the morphology manipulation of Cu nanowires by adjusting the stirring rate and the amounts of ethylenediamine and hydrazine (N2H4), yielding Cu nanowires with either smooth or rough surface. Importantly, according to our experimental results and theoretical investigation, new functions of ethylenediamine and N2H4 are found, and a growth process of Cu nanowires is proposed accordingly. In addition to typically accepted roles of ethylenediamine and N2H4, we find that ethylenediamine can facilitate the growth of Cu nanowires by etching Cu oxides and even Cu on the surface of Cu nanowires. Meanwhile, N2H4 molecules can modulate the growth of Cu nanowires as a capping agent, which can be easily influenced by stirring. Additionally, the as-synthesized Cu nanowires with different morphologies exhibit different optical and catalytic properties. This study provides new fundamental insights into the growth mechanism of Cu nanowires, and thus can facilitate controlled synthesis of Cu nanowires for further applications, including electronics, catalysis, and sensing.

5.
J Phys Chem Lett ; 10(10): 2349-2356, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31007024

RESUMO

Reduced-dimensional (RD) perovskite solar cells (PSCs) are emerging as highly attractive alternatives to three-dimensional (3D) PSCs due to their dramatically improved environmental stability and photostability. Diamine-based RD perovskites with a single organic amine interlayer possess orderly inorganic sheets and a smaller insulation area, indicating great potential in combining high efficiency and long-term stability. Here, we report an efficient and stable RD PSC based on 1,4-butanediamine (BDA). We found that the BDA-based RD perovskite exhibits improved crystallinity, reduced trap-state densities, and enhanced charge mobility compared to those of butylamine (BA)-based RD (BA-RD) perovskite. A high power conversion efficiency of 17.91% was achieved with negligible hysteresis. Moreover, the device showed improved stability compared to those of BA-RD and 3D films and devices. The findings may inspire new developments in introducing organic diamine for efficient and stable RD PSCs.

6.
Front Chem ; 7: 21, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30761291

RESUMO

Black phosphorus, an emerging layered material, exhibits promising applications in diverse fields, ranging from electronics to optics. However, controlled synthesis of black phosphorus, particularly its few-layered counterparts, is still challenging, which should be due to the unclear growth mechanism of black phosphorus. Here, taking the most commonly used Sn-I assisted synthesis of black phosphorus as an example, we propose a growth mechanism of black phosphorus crystals by monitoring the reactions and analyzing the as-synthesized products. In the proposed mechanism, Sn24P19.3I8 is the active site for the growth of black phosphorus, and the black phosphorus crystals are formed with the assistance of SnI2, following a polymerization-like process. In addition, we suggest that all Sn-I assisted synthesis of black phosphorus should share the same reaction mechanism despite the differences among Sn-I containing additives. Our results shown here should shed light on the controlled synthesis of black phosphorus and facilitate further applications of black phosphorus.

7.
J Am Chem Soc ; 140(45): 15507-15515, 2018 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-30350963

RESUMO

The combination of metal-organic frameworks (MOFs) and luminescent nanomaterials with upconversion characteristics could enable the development of new nanomaterials and applications in information security, optical sensing, and theranostics. However, currently available methods are not ideally suitable for fabricating composites of MOF and upconversion nanomaterial, and incorporating upconversion nanomaterials with MOFs in a controllable manner remains challenging. Here, we demonstrate an in situ self-assembly route to the nanocomposites in which MOFs are homogeneously paved with upconversion nanoparticles. Without additional assistance, this strategy, mainly driven by electrostatic interactions, can be used to incorporate different upconversion nanoparticles with diverse MOFs. The as-synthesized composites can be further used to construct composites with unique structures, such as MOF@upconversion nanoparticles@MOF sandwiched nanocomposites, and would be useful for applications including luminescence-monitored drug delivery, anticounterfeiting, and photodynamic therapy. These findings should shed light on new avenues for fabricating multifunctional composites of MOF and upconversion nanomaterials for varied applications.

8.
Parkinsons Dis ; 2018: 9163040, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30245802

RESUMO

Parkinson's disease (PD) is the second most common neurodegenerative disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra. The precise mechanism underlying pathogenesis of PD is not fully understood, but it has been widely accepted that excessive reactive oxygen species (ROS) are the key mediator of PD pathogenesis. The causative factors of PD such as gene mutation, neuroinflammation, and iron accumulation all could induce ROS generation, and the later would mediate the dopaminergic neuron death by causing oxidation protein, lipids, and other macromolecules in the cells. Obviously, it is of mechanistic and therapeutic significance to understand where ROS are derived and how ROS induce dopaminergic neuron damage. In the present review, we try to summarize and discuss the main source of ROS in PD and the key pathways through which ROS mediate DA neuron death.

9.
Nature ; 561(7721): 88-93, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30150772

RESUMO

The rising demand for radiation detection materials in many applications has led to extensive research on scintillators1-3. The ability of a scintillator to absorb high-energy (kiloelectronvolt-scale) X-ray photons and convert the absorbed energy into low-energy visible photons is critical for applications in radiation exposure monitoring, security inspection, X-ray astronomy and medical radiography4,5. However, conventional scintillators are generally synthesized by crystallization at a high temperature and their radioluminescence is difficult to tune across the visible spectrum. Here we describe experimental investigations of a series of all-inorganic perovskite nanocrystals comprising caesium and lead atoms and their response to X-ray irradiation. These nanocrystal scintillators exhibit strong X-ray absorption and intense radioluminescence at visible wavelengths. Unlike bulk inorganic scintillators, these perovskite nanomaterials are solution-processable at a relatively low temperature and can generate X-ray-induced emissions that are easily tunable across the visible spectrum by tailoring the anionic component of colloidal precursors during their synthesis. These features allow the fabrication of flexible and highly sensitive X-ray detectors with a detection limit of 13 nanograys per second, which is about 400 times lower than typical medical imaging doses. We show that these colour-tunable perovskite nanocrystal scintillators can provide a convenient visualization tool for X-ray radiography, as the associated image can be directly recorded by standard digital cameras. We also demonstrate their direct integration with commercial flat-panel imagers and their utility in examining electronic circuit boards under low-dose X-ray illumination.

10.
ACS Sens ; 3(9): 1683-1689, 2018 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-30095257

RESUMO

Detection of dopamine, an important neurotransmitter, is vital for understanding its roles in mammals and disease diagnosis. However, commonly available methods for dopamine detection typically rely on a single signal readout, which can be susceptible to interference by internal or external factors. Here, we report a dual-signal detection of dopamine based on label-free luminescent NaGdF4:Tb nanoparticles. In the presence of dopamine, the NaGdF4:Tb nanoparticles exhibit luminescence quenching under the excitation of 272 nm, while they give enhanced luminescence under 297 nm excitation, realizing both turn off and turn on detection of dopamine. The nanoparticle-based dual-signal sensors exhibit high sensitivity, with a detection limit of ∼30 nM, and good selectivity, which offers the possibility to identify potential interferents in the samples. We further demonstrate that the dual-signal response results from different energy-transfer processes within the nanoparticles under the excitation of different light. The new strategy demonstrated here should pave the way for the development of multiresponse nanosensors based on lanthanide-doped luminescent nanomaterials.


Assuntos
Dopamina/análise , Substâncias Luminescentes/química , Medições Luminescentes/métodos , Nanopartículas Metálicas/química , Neurotransmissores/análise , Dopamina/sangue , Dopamina/efeitos da radiação , Dopamina/urina , Transferência de Energia , Gadolínio/química , Gadolínio/efeitos da radiação , Humanos , Limite de Detecção , Luminescência , Substâncias Luminescentes/efeitos da radiação , Nanopartículas Metálicas/efeitos da radiação , Neurotransmissores/sangue , Neurotransmissores/efeitos da radiação , Neurotransmissores/urina , Térbio/química , Térbio/efeitos da radiação , Raios Ultravioleta
11.
ACS Appl Mater Interfaces ; 10(30): 25121-25126, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29986136

RESUMO

The capability of transferring target materials especially functionality-reliable biomolecules, into specific locations and with arbitrarily designed patterns are of critical importance for high-throughput disease diagnosis, multiplexing, and drug screening. Herein, we report the simultaneous patterning of two types of biomolecules using the parallel dip-pen nanolithography technology where an array of the atomic force microscope (AFM) tips can be selectively and alternately coated with target biomolecules via a specially designed inkwell array. Moreover, mixing target biomolecules at a proper volumetric ratio with polyethylene glycol dissolved in PBS buffer solution that works as an ink carrier can not only facilitate the smooth transfer of ink materials from the AFM tip to the substrate, it can also help to adjust the ink diffusion constant of different biomolecules to be highly similar so that the multiplexed biofunctional dot and/or line arrays at similar sizes can be reliably generated.


Assuntos
Nanotecnologia , Microscopia de Força Atômica , Polietilenoglicóis
12.
Analyst ; 143(14): 3433-3441, 2018 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-29916502

RESUMO

Investigating the change in expression level of mercapto biomolecules (GSH/Cys/Hcy) necessitates a rapid detection method for a series of physiological and pathological processes. Herein, we present a ligand-displacement-based two-photon fluorogenic probe based on an Fe(iii) complex, TPFeS, which is a GSH/Cys/Hcy rapid detection fluorogenic probe for in vitro analysis and live cell/tissue/in vivo imaging. The "in situ" probe is non-fluorescent and was prepared from a 1 : 2 ratio of Fe(iii) and TPS, a novel two-photon (TP) fluorophore with excellent one-photon (OP) and TP properties under physiological conditions, as a fluorescent ligand. This probe shows a rapid and remarkable fluorescence restoration (OFF-ON) property due to the ligand-displacement reaction of mercapto biomolecules in a recyclable manner in vitro. A significant two-photon action cross-section, good selectivity for biothiols, low cytotoxicity, and insensitivity to pH over the biologically relevant pH range allowed the direct visualization of mercapto biomolecules at different levels between normal/drug-treated live cells, as well as in Drosophila brain tissues/zebrafish based on the use of two-photon fluorescence microscopy.


Assuntos
Química Encefálica , Compostos Férricos , Corantes Fluorescentes , Compostos de Sulfidrila/análise , Animais , Encéfalo , Drosophila , Fótons , Peixe-Zebra
13.
Dalton Trans ; 47(14): 4950-4958, 2018 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-29553152

RESUMO

Scandium (Sc) sits at a unique position in the periodic table, i.e., the junction of the top of the rare earth column and the beginning of the transition metal row. Studies have shown that Sc-based nanomaterials are very sensitive to the surrounding chemical environment. A simple adjustment of the chemical reaction conditions such as temperature, surfactant molecules, and solvents (e.g., oleic acid (OA) or 1-octadecene (OD)) can easily lead to different products in terms of chemical composition and phase structure. Herein, under purposely adjusted reaction conditions, we have investigated the interconversion process between two representative Sc-based nanomaterials, that is, nanocrystals of orthorhombic KSc2F7:Yb/Er and cubic K2NaScF6:Yb/Er, both of which have characteristic red upconversion luminescence and high similarity in chemical composition and phase structure. Experimental results have indicated that conversion from KSc2F7:Yb/Er to K2NaScF6:Yb/Er may start from the edge of the nanocrystal where K+ in KSc2F7:Yb/Er was gradually substituted by the post-introduced Na+ in the solution and finally KSc2F7:Yb/Er nanorods were broken and K2NaScF6:Yb/Er nanocubes were formed. On the other hand, a simple variation of the OA : OD ratio facilitates the dissolution of K2NaScF6:Yb/Er and subsequent crystallization of KSc2F7:Yb/Er during the opposite conversion process. Possible chemical reaction mechanisms were further developed to elucidate the interconversion details. Meanwhile, the variation of the upconversion luminescence such as emission intensity, red to green ratio, and lifetime is interpreted to monitor the conversion progress at corresponding stages, which is highly consistent with the scenario discussed above.

14.
ACS Appl Mater Interfaces ; 10(15): 12431-12440, 2018 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-29564897

RESUMO

In preclinical and clinical research, to destroy cancers, particularly those located in deep tissues, is still a great challenge. Photodynamic therapy and photothermal therapy are promising alternative approaches for tissue cancer curing. Black phosphorus (BP)-based nanomaterials, with broad UV-vis near-infrared absorbance and excellent photothermal effect, have shown great potential in biomedical applications. Herein, a biocompatible therapeutic platform, chlorin e6 (Ce6)-decorated BP nanosheets (NSs), has been developed for fluorescence and thermal imaging-guided photothermal and photodynamic synergistic cancer treatment. Taking advantage of the relatively high surface area of exfoliated BP NSs, the PEG-NH2-modified BP NSs (BP@PEG) are loaded with a Ce6 photosensitizer. The resulted BP@PEG/Ce6 NSs not only have good biocompatibility, physiological stability, and tumor-targeting property but also exhibit enhanced photothermal conversion efficiency (43.6%) compared with BP@PEG NSs (28.7%). In addition, BP@PEG/Ce6 NSs could efficiently generate reactive oxygen species because of the release of the Ce6 photosensitizer, which is also verified by in vitro studies. In vivo fluorescence imaging suggests that BP@PEG/Ce6 NSs can accumulate in the tumor targetedly through the enhanced permeability and retention effect. Both in vitro and in vivo studies suggest that BP@PEG/Ce6 can be a promising nanotheranostic agent for synergetic photothermal/photodynamic cancer therapy.


Assuntos
Fósforo/química , Linhagem Celular Tumoral , Humanos , Nanoestruturas , Fotoquimioterapia , Fármacos Fotossensibilizantes
15.
Adv Mater ; 30(14): e1705256, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29430797

RESUMO

Luminescent nanothermometers have shown competitive superiority for contactless and noninvasive temperature probing especially at the nanoscale. Herein, we report the inherently Eu2+ /Eu3+ codoped Sc2 O3 nanoparticles synthesized via a one-step and controllable thermolysis reaction where Eu3+ is in-situ reduced to Eu2+ by oleylamine. The stable luminescence emission of Eu3+ as internal standard and the sensitive response of Eu2+ emission to temperature as probe comprise a perfect ratiometric nanothermometer with wide-range temperature probing (77-267 K), high repeatability (>99.94%), and high relative sensitivity (3.06% K-1 at 267 K). The in situ reduction of Eu3+ to Eu2+ ensures both uniform distribution in the crystal lattice and simultaneous response upon light excitation of Eu2+ /Eu3+ . To widen this concept, Tb3+ is codoped as additional internal reference for tunable temperature probing range.

16.
Nat Commun ; 8(1): 899, 2017 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-29026084

RESUMO

Optical characteristics of luminescent materials, such as emission profile and lifetime, play an important role in their applications in optical data storage, document security, diagnostics, and therapeutics. Lanthanide-doped upconversion nanoparticles are particularly suitable for such applications due to their inherent optical properties, including large anti-Stokes shift, distinguishable spectroscopic fingerprint, and long luminescence lifetime. However, conventional upconversion nanoparticles have a limited capacity for information storage or complexity to prevent counterfeiting. Here, we demonstrate that integration of long-lived Mn2+ upconversion emission and relatively short-lived lanthanide upconversion emission in a particulate platform allows the generation of binary temporal codes for efficient data encoding. Precise control of the particle's structure allows the excitation feasible both under 980 and 808 nm irradiation. We find that the as-prepared Mn2+-doped nanoparticles are especially useful for multilevel anti-counterfeiting with high-throughput rate of authentication and without the need for complex time-gated decoding instrumentation.Luminescent materials that are capable of binary temporal coding are desirable for multilevel anti-counterfeiting. Here, the authors engineer nanoparticles that produce binary color codes on different timescales by combining the long-lived luminescence of Mn2+ with the relatively short-lived emission of lanthanides.

17.
Nanoscale ; 9(41): 15974-15981, 2017 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-29019505

RESUMO

The synthesis of REF3 (RE = La-Lu, Y) nanocrystals with controlled phase structures has so far remained a challenge. Herein we have developed a one-for-all synthetic procedure that allows the successful synthesis of REF3 nanocrystals in a controlled manner. Experimental results showed that the radius of RE ions determines the phase structure: pure hexagonal REF3 (RE = La-Eu), a mixture of hexagonal and orthorhombic REF3 (RE = Gd), and pure orthorhombic REF3 (RE = Tb-Lu, Y) nanocrystals are obtained along with the decrease of the ionic radius. As Gd is positioned exactly in the middle of the lanthanides row, GdF3 nanocrystals were used as a model to further investigate how the molar ratio of F- : Gd3+, the doping of RE ions with different ionic radii, and the doping concentration of certain RE ions affects the crystal structure of the final product.

19.
Nanoscale ; 9(36): 13739-13746, 2017 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-28884767

RESUMO

Enhancing upconversion emission is critical for small-sized lanthanide doped upconversion nanocrystals. A promising way is increasing the doping concentration of excitation energy absorbers, the Yb3+ sensitizer. However, it is still a challenge to obtain small-sized hexagonal NaLnF4 (Ln: lanthanide) upconversion nanocrystals with a high Yb3+ concentration due to the fast growth of NaYbF4 crystals, which hinders their applications particularly in biology. We here demonstrate a highly repeatable and controllable method for tuning the size of hexagonal NaYbF4 nanocrystals, down to ∼7 nm, without the assistance of additional impurity doping. By monitoring the reaction process, we found that ultrasmall hexagonal NaYbF4 nanocrystals were formed through an in situ transformation of their cubic counterparts. We observed an enhanced upconversion emission of NaYbF4:Tm nanocrystals when compared to that of NaYbF4:Y/Tm nanocrystals with less Yb3+ doping. After coating a thin layer of a NaYF4 shell on NaYbF4:Tm nanocrystals, a ∼100 times upconversion emission enhancement with over 800 times stronger emission in the ultraviolet and blue ranges was observed. This versatile method, together with the strong upconversion emission of the as-prepared ultrasmall nanocrystals, should facilitate the future applications of upconversion nanocrystals.

20.
Adv Mater ; 29(37)2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28804927

RESUMO

Topological control of nanostructures plays a crucial role in understanding the crystal growth process at the nanometer length scale. Here, the scalable synthesis of upconversion materials with distinct hedgehog-like morphologies by a seed-mediated synthetic procedure is reported. It is demonstrated that a close match in the crystal lattice between the core and shell components is essential for synthesizing such hierarchical nanostructures. These optical nanomaterials also enable the development of a single-particle-based platform for high-sensitivity molecular sensing.

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