Lead halide perovskite quantum dots (QDs) are promising electrochemiluminescence (ECL) nanoemitters due to their fascinating photophysical properties. However, due to their poor structural stability ...against the external environment, the trade‐off between their colloidal stability and carrier injection/transport efficiency is a major challenge in the advancement of perovskite‐based ECL technology. In this work, intense and stable ECL from CsPbBr3 (CPB) QDs is achieved by simultaneously encapsulating CPB QDs and coreactant (CoR) into in situ generated SiO2 matrix via hydrolysis of tetramethyl orthosilicate. The well‐designed architecture of the as‐obtained CPB‐CoR@SiO2 nanocomposites (NCs) guarantees not only greatly improved stability thanks to the peripheral SiO2 protecting matrix, but also efficient self‐enhanced ECL between CPB and the intra‐coreactants. Consequently, by elaborately selecting the CoR molecules with different tertiary/secondary amines and functional groups, multifold higher (up to 10.2 times) ECL efficiencies are obtained for the CPB‐CoR@SiO2 NCs alone in reference to the standard Ru(bpy)32+/tri‐n‐propylamine system. This work provides an efficient design strategy for obtaining stable and highly efficient ECL from perovskite QDs, and offers a new perspective for the development and application of perovskite‐based ECL system.
Ternary CsPbBr3 perovskite suprastructures with self‐enhanced electrochemiluminescence and improved stability is prepared by simultaneously encapsulating CsPbBr3 quantum dots and coreactant into in situ generated SiO2 matrix via hydrolysis of tetramethyl orthosilicate. The obtained nanocomposites exhibit higher (up to 10.2 times) electrochemiluminescence efficiencies in reference to the standard Ru(bpy)32+/tri‐n‐propylamine system.
We introduce here the concept of acoustic parity-time (PT ) symmetry and demonstrate the extraordinary scattering characteristics of the acoustic PT medium. On the basis of exact calculations, we ...show how an acoustic PT -symmetric medium can become unidirectionally transparent at given frequencies. Combining such a PT -symmetric medium with transformation acoustics, we design two-dimensional symmetric acoustic cloaks that are unidirectionally invisible in a prescribed direction. Our results open new possibilities for designing functional acoustic devices with directional responses.
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Engineering of efficient and safe materials remains a challenge for cancer therapy. Here, the lipid droplet, an organelle in adipocytes, is demonstrated to be a controllable and biocompatible vehicle ...to deliver anticancer drugs. It is validated that isolated lipid droplets maintain their key physiological functions to interact with other organelles and augment the therapeutic effect of cancer photodynamic therapy by encapsulation with a lipid‐conjugated photosensitizer (Pyrolipid) through a variety of pathways, including generation of reactive oxygen species (ROS); lipid peroxidation; and endoplasmic reticulum (ER) stress. As such, the IC50 value of Pyrolipid is reduced by 6.0‐fold when loaded into the lipid droplet. Of note, in vivo results demonstrate that engineered lipid droplets induce significant inhibition of tumor growth with minimal side effects.
The lipid droplet, an organelle in adipocytes, is engineered to be a controllable, effective, and biocompatible drug delivery system for cancer therapy. It is demonstrated that the lipid droplet can augment the therapeutic performance of an encapsulated drug via several pathways, including generation of reactive oxygen species, lipid peroxidation, and endoplasmic reticulum stress, providing a promising material with clinical translation potential.
Intracellular microRNAs imaging based on upconversion nanoprobes has great potential in cancer diagnostics and treatments. However, the relatively low detection sensitivity limits their application. ...Herein, a lock‐like DNA (LLD) generated by a hairpin DNA (H1) hybridizing with a bolt DNA (bDNA) sequence is designed, which is used to program upconversion nanoparticles (UCNPs, NaYF4@NaYF4:Yb, Er@NaYF4) and gold nanoparticles (AuNPs). The upconversion emission is quenched through luminescence resonance energy transfer (LRET). The multiple LLD can be repeatedly opened by one copy of target microRNA under the aid of fuel hairpin DNA strands (H2) to trigger disassembly of AuNPs from the UCNP, resulting in the lighting up of UCNPs with a high detection signal gain. This strategy is verified using microRNA‐21 as model. The expression level of microRNA‐21 in various cells lines can be sensitively measured in vitro, meanwhile cancer cells and normal cells can be easily and accurately distinguished by intracellular microRNA‐21 imaging via the nanoprobes. The detection limit is about 1000 times lower than that of the previously reported upconversion nanoprobes without signal amplification. This is the first time a nonenzymatic signal amplification method has been combined with UCNPs for imaging intracellular microRNAs, which has great potential for cancer diagnosis.
A sensitive upconversion nanoprobe is developed for detecting microRNA in vitro and imaging microRNA in living cells by the disassembly of lock‐like DNA‐programmed upconversion nanoparticles (NPs)‐AuNPs through the target cycling amplification strategy. This nanoprobe can sensitively measure microRNA‐21 in real samples and enables facile and accurate differentiation between cancer cells and normal cells.
Environmental Science & Technology (ES&T) has served a leadership role in reporting advanced and significant research findings for decades and accumulated tremendous amount of high-quality ...literature. In this study, we developed tailored text mining methods and analyzed 29 188 papers published in ES&T from 2000 to 2019, and we performed data-driven analyses to reveal some critical information and guidance on what has been published, what topical changes have evolved, and what are the areas that deserve additional attention. While top research keywords remained stable (water, sorption, soil, emiss, oxid, exposur), the trending up and emerging keywords showed clear shift over the years. Keywords related to nanobased materials (nanoparticl, nanomateri, carbon nanotub), climate and energy (climat, ch4, greenhouse gas emiss, mitig, energi), and health (exposur, health, ingest) demonstrated the strongest uptrend in the past 10 years, while plastics and PFAS were among clear emerging topics in the past 5 years. Co-occurrence analysis showed distinct associations between media (water, soil, air, sediment), chemicals (pcb, humic subst, particulate matt), processes (sorption, remov, degrad), and properties (kinet, mechan, speciat). Furthermore, a rule-based classification deciphered trends, distributions, and interconnections of articles based on either monodomains (air, soil, solid waste, water, and wastewater) or multidomains. It found water and wastewater cross-discipline articles tended to have higher citation values, while air domain tended to stand alone. Water and air monodomains consistently increased their shares in publications (together 56.3% in 2019), while shares of soil studies gradually declined. This study provides new data-driven methods on literature mining and offers unique insights on environmental research landscape and opportunities.
Quantum dots (QDs), nano-carriers for drugs, can help realize the targeting of drugs, and improve the bioavailability of drugs in biological fields. And, a QD nano-carrier system for drugs has the ...potential to realize early detection, monitoring, and localized treatments of specific disease sites. In addition, QD nano-carrier systems for drugs can improve stability of drugs, lengthen circulation time in vivo, enhance targeted absorption, and improve the distribution and metabolism process of drugs in organization. So, the development of QD nano-carriers for drugs has become a hotspot in the fields of nano-drug research in recent years. In this paper, we review the advantages and applications of the QD nano-carriers for drugs in biological fields.
The ability to slow down wave propagation in materials has attracted significant research interest. A successful solution will give rise to manageable enhanced wave-matter interaction, freewheeling ...phase engineering and spatial compression of wave signals. The existing methods are typically associated with constructing dispersive materials or structures with local resonators, thus resulting in unavoidable distortion of waveforms. Here we show that, with helical-structured acoustic metamaterials, it is now possible to implement dispersion-free sound deceleration. The helical-structured metamaterials present a non-dispersive high effective refractive index that is tunable through adjusting the helicity of structures, while the wavefront revolution plays a dominant role in reducing the group velocity. Finally, we numerically and experimentally demonstrate that the helical-structured metamaterials with designed inhomogeneous unit cells can turn a normally incident plane wave into a self-accelerating beam on the prescribed parabolic trajectory. The helical-structured metamaterials will have profound impact to applications in explorations of slow wave physics.
DNAzymes have enjoyed success as metal ion sensors outside cells. Their susceptibility to metal‐dependent cleavage during delivery into cells has limited their intracellular applications. To overcome ...this limitation, a near‐infrared (NIR) photothermal activation method is presented for controlling DNAzyme activity in living cells. The system consists of a three‐stranded DNAzyme precursor (TSDP), the hybridization of which prevents the DNAzyme from being active. After conjugating the TSDP onto gold nanoshells and upon NIR illumination, the increased temperature dehybridizes the TSDP to release the active DNAzyme, which then carries out metal‐ion‐dependent cleavage, resulting in releasing the cleaved product containing a fluorophore. Using this construct, detecting Zn2+ in living HeLa cells is demonstrated. This method has expanded the DNAzyme versatility for detecting metal ions in biological systems under NIR light that exhibits lower phototoxicity and higher tissue penetration ability.
Gold in the shell: A near‐IR light‐activated DNAzyme–gold nanoshell system has been developed. It was then applied for imaging metal ions in living cells.
The catalytic activity of nanocrystal catalysts depends strongly on their structures. Herein, we report three distinct structures of Fe3O4 nanocrystals, cluster spheres, octahedra, and triangular ...plates, prepared by a similar hydrothermal procedure. Additionally, the three Fe3O4 nanostructures were used as peroxidase nanomimetics and the correlation between the catalytic activities and the structures was first explored by using 3,3′,5,5′‐tetramethylbenzidine and H2O2 as peroxidase substrates. The results showed that the peroxidase‐like activities of the Fe3O4 nanocrystals were structure dependent and followed the order cluster spheres>triangular plates>octahedra; this order was closely related to their preferential exposure of catalytically active iron atoms or crystal planes. Such investigation is of great significance for peroxidase nanomimetics with enhanced activity and utilization.
A question of shape: Three distinct structures of Fe3O4 nanocrystals, cluster spheres, octahedra, and triangular plates, have been fabricated by a similar hydrothermal procedure. These different Fe3O4 nanostructures had different specific surface areas and exposed crystal planes, and thus exhibited different levels of peroxidase‐like activities, in the order of cluster spheres> triangular plates>octahedra (see figure).
With the assistance of microwave irradiation, greenish‐yellow luminescent graphene quantum dots (gGQDs) with a quantum yield (QY) up to 11.7% are successfully prepared via cleaving graphene oxide ...(GO) under acid conditions. The cleaving and reduction processes are accomplished simultaneously using microwave treatment without additional reducing agent. When the gGQDs are further reduced with NaBH4, bright blue luminescent graphene quantum dots (bGQDs) are obtained with a QY as high as 22.9%. Both GQDs show well‐known excitation‐dependent PL behavior, which could be ascribed to the transition from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) with a carbene‐like triplet ground state. Electrochemiluminescence (ECL) is observed from the graphene quantum dots for the first time, suggesting promising applications in ECL biosensing and imaging. The ECL mechanism is investigated in detail. Furthermore, a novel sensor for Cd2+ is proposed based on Cd2+ induced ECL quenching with cysteine (Cys) as the masking agent.
Two‐color graphene quantum dots are prepared using a facile microwave‐assisted approach to have fluorescent quantum yields as high as 22.9%. The graphene quantum dots are demonstrated to be electrochemiluminescent. A novel electrochemiluminescence sensor for Cd2+ is proposed based on the competitive coordination between cysteine and graphene quantum dots for metal ions.
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