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The mechanism of enhanced photocatalytic indole cation-radical cyclization in confined space is examined by coupling a nanopipette reactor with in situ nano-electrospray mass spectrometry (nanoESI-MS).

Due to their special physicochemical properties, organic-inorganic hybrid perovskite quantum dots (OIP QDs) are ideal and potential catalysts for the nitrogen reduction reaction (NRR). However, the OIP QD-based NRR is limited by poor water resistance, competitive suppression by the hydrogen evolution reaction, and inefficient active sites on the catalyst surfaces. Herein, to ensure an efficient NRR in aqueous solution, a water-resistant polycarbonate-part-encapsulated heterojunction of Zn,Pt

Developments in framework nucleic acids (FNAs) are limited by complicated synthesis, by-product interference, and low framework utilization. Herein, simple core–shell spherical 3D FNAs (ST-SFNAs) preparation is presented based on siRNA-templated linear polymerization followed by hybridization chain reaction branched polymerization. Without by-products, all components exhibited their special functions to obtain high space utilization of ST-SFNAs. ST-SFNAs were covered by catalase and folic acid-functionalized liposome membranes. The catalase endowed ST-SFNAs with chemotactic activities in the H2O2 reaction catalyzed by catalase. Furthermore, combined with functionalized folic acids' targeting folate receptors, the synergistic chemotactic recognition of cancer cells was obtained. This dramatically promoted targeted cellular uptakes compared with traditional active or passive targeting pathways. Subsequently, the cascaded-logical programmable release of drugs was precisely controlled by targeting glutathione and ATP (via S–S bond and ATP aptamer on the inner g-DNA cover). This was visualized by “turn on” fluorescent signals generated by special hybridization of released hairpin DNAs with survivin mRNA biomarkers. Simultaneously, biocompatible synergistic therapy was achieved by simultaneously releasing doxorubicin and siRNA. With its high utilization for synergistic chemotactic recognition, programmable and visualized delivery, as well as synergistic therapy, an efficient platform for maximizing the therapeutic efficacy has been developed. This would initiate further FNA-based material development for a variety of biological applications., ST-SFNAs were developed by siRNA-templated linear-branched polymerizations with high space utilizations for loadings, which obtained synergistic cancer therapy via chemotactic recognition, visualized delivery, and cascaded-logical controlled release.

The rapid degradation of organic pollutants, process monitoring and online controlling to obtain advanced products and decreased by-products are great and challenging tasks in environmental treatments. Herein, an accelerated plasma degradation in milliseconds was achieved by combining electrospray-based acceleration and plasma-based degradation. Taking the degradation of chloroaniline as an example, 97% of the degradation can be achieved in milliseconds. The velocity distribution of droplets was determined to be 40–50 m/s after being degraded for 0.30 ms, which exhibited different degradation behaviors in different milliseconds. Simultaneously, by virtue of the real-time and on-line detection ability of ambient mass spectrometry, intermediates, by-products and advanced products were monitored. Therefore, degradation mechanisms for different degradation times were proposed, which would provide theoretical guidance on obtaining efficient and green degradation. The fabrication, examining and understanding of accelerated plasma degradation not only enlarged application of accelerated reactions, but also promoted green and efficient degradation for environmental treatments.

Online mass spectrometry was applied to reveal multiple mechanisms of visible-light irradiated dye-sensitized photocatalysis for o-phenylenediamine oxidation. The reactants, products and short-lived intermediates were recorded and dynamically tracked. Dimer and unexpected trimer intermediates were observed to deduce the stepwise aerobic photooxidation mechanism with multiple routes, which was supported by theoretical calculations.

The TEMPO-electrocatalyzed acceptorless dehydrogenation of tetrahydroquinoline, a transformation in green synthesis and hydrogen storage, has been investigated by coupling of an electrocatalytic system with in situ extraction electrospray ionization mass spectrometry. Dynamic changes in important species and intermediates were monitored, which evoked an updated AD understanding.

Electrospray ionization mass spectrometry (ESI-MS) is one of the most popular techniques for obtaining structural information, which is commonly used in bioanalysis and clinical diagnostics. However, for the detection of complicated samples with high reactivities (such as reactive sulfur species, RSS), traditional ESI-MS usually suffers from overlapped and inaccurate signals. In this study, based on the multiphase flow of extractive electrospray ionization (MF-EESI), an ambient MS technique of online derivatization was proposed to detect thiols without any other sample pretreatment.RSS molecules and the derivatization reagent of 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) were introduced into the internal and innermost capillary of the MF-EESI system, respectively. By a high-velocity nebulizing stream of NBy evaluating the changes in MS signals before and after the derivatization, the ions of RSS were identified simply and correctly. Without any sample pretreatment, the fast detection of cysteine, homocysteine, and glutathione has been achieved in the complicated samples.The present online derivatization-based MF-EESI was successfully used for fast, simple, and accurate detection of biothiols. This presented a potential pathway for the fast identification of thiols in complicated samples.

The new development of noninvasive diagnosis in breath analysis requires the fabrication of inexpensive and rapid sensing technologies, whose sensing mechanisms are further encouraged to be studied. Here based on the dramatically enhanced plasma-assisted cataluminescence (PA-CTL) signals, a new sensor was constructed for the detection of acetone, an important biomarker of diabetes mellitus in breath. As demonstrated, the PA-CTL-based sensor showed good sensitivity, repeatability, and selectivity in acetone detection, which also displayed good recovery and stability in exhaled breath. An online ionization system of low-temperature plasma mass spectrometry was designed to couple with the PA-CTL sensor for examining changes of molecules during the sensing. For the first time, some important ions were recorded in real time, which helped to clear the reaction mechanism of radical-based catalytic oxidation combined with the CTL data. By the fabrication and relative comprehensive understanding of the PA-CTL sensor for acetone detection, this work would promote the development of CTL sensing techniques and inspire a potential pathway for rapid and noninvasive diagnosis.

Applying organic-inorganic hybrid perovskite quantum dots (PQDs) to photocatalytic nitrogen fixation is hindered long-term by the inherent instability in water and tedious preparations. Here, to realize PQD-catalyzed photocatalytic N2 reduction reaction (NRR), water-resistant PQDs are simply prepared through one-step electrospray synthesis in microseconds. During the fast electrospray, PQDs of Zn/PbO-doped methylammonium lead bromide (Zn/PbO/PC-Zn/MAPbBr3 , MA: CH3 NH3 ) are prepared and part-encapsulated by polycarbonate. The synthesis maintains good water resistance, whose restriction on charge transport is overcome skillfully. Simultaneously, substitution of Zn with Pb on water-resistant surface is also achieved, which fabricates new Zn-oxygen vacancies (Zn-OVs) with Zn/PbO-Zn/MAPbBr3 type I heterojunction. This facilitates efficient electron transfer from internal heterojunction interface of Zn/MAPbBr3 PQDs to the surface of Zn/PbO. Demonstrated by theoretical calculations, Zn-OVs promote chemisorption and polarization of N2 . In addition, s-electrons in exposed Zn become active due to changes of electron filling of Zn orbitals under OVs' co-doping. Thus, photocatalytic N2 reduction reaction catalyzed by organic-inorganic hybrid PQDs is first achieved in aqueous phase without sacrificial agents being added. This initiates possibilities for photocatalytic applications of organic-inorganic hybrid PQDs in aqueous phase.

The TEMPO-electrocatalyzed acceptorless dehydrogenation of tetrahydroquinoline, a transformation in green synthesis and hydrogen storage, has been investigated by coupling of an electrocatalytic system with in situ extraction electrospray ionization mass spectrometry. Dynamic changes in important species and intermediates were monitored, which evoked an updated AD understanding.

The efficient delivery of biomolecules into living cells as well as their easy biodegradation have been challenges for the application of intracellular amplification for sensitive multiple-diagnosis and gene therapy for cancer. Herein, new strategies of amplification-based dual-detection of cancer biomarkers (Let-7a miRNA and VEGF) and gene therapy for cancers are put forward. These are achieved through biodegradable nanosyringes (NSs), rigid and sharp in vitro but degradable in vivo, which are applied for the efficient loading, delivery and release of biomolecules (enzymes, nucleic acids, and even silencing RNA) into living cells. After penetrating cell membranes and escaping from endosomes through their rigid and sharp tips, NSs release biomolecules for fast and easy “one-step” rolling circle amplification (ring formation and amplification) in single living cells. Therefore, based on signals from two probes, FAM-Probe and Cy5-Probe, that selectively bind to amplification products, 100 aM of Let-7a and 100 fM of VEGF could be detected, which are much lower than reported values. Furthermore, siRNAs can also be delivered by NSs for gene therapy, and their therapeutic effect was evaluated by their in vivo antitumor efficacy in CCRF-CEM subcutaneous xenograft nude mice. Rigid in vitro and degradable in vivo, NSs show potential for achieving fast, sensitive and safe cancer diagnosis and efficient therapy.

An upconversion nanoparticle (UCNP)-based fluorescence resonance energy-transfer (FRET) strategy is normally restricted by the complicated preparations, low energy-transfer efficiency, and the challenge on improving specificity. Herein, simple DNA-functionalized UCNPs were designed as energy donors for constructing a FRET-based probe to detect the liver-specific microRNA 122 (miR-122). To improve FRET efficiency, UCNPs were constructed with confined core-shell structures, in which emitting ions were precisely located in the thin shell to make them close enough to external energy acceptors. Subsequently, capture DNA was simply functionalized on the outer surface of UCNPs based on ligand exchange that contributed to shortening the energy-transfer distance without extra modification. To gain high specificity, the donor-to-acceptor distance of FRET was controlled by a sandwich DNA hybridization structure using two shorter DNAs with designed complementary sequences (capture DNA and dye-labeled report DNA) to capture the longer target of miR-122. Therefore, the sensitive detection of miR-122 was achieved based on the decreased signals of UCNPs and the increased signals of the dye labeled on reported DNA. With good biocompatibility, this method has been further applied to cancer cell imaging and in vivo imaging, which opened up a new avenue to the sensitive detection and imaging of microRNA in biological systems.

The photocatalytic [3+2] cycloadditions of phenols and olefins are normally limited by the relatively tedious process. Herein, based on accelerated microdroplet reactions, a nano-electrospray ionization (nESI) was constructed for online acceleration of photocatalytic [3+2] cycloaddition between phenols and olefins. As demonstrated, the high reaction rates were obtained by nESI tips with smaller orifice inner diameter and the electrode closed to the nESI tip. These were further confirmed by the calculations on the conversion ratios and apparent acceleration factors. Meanwhile, the important intermediates (especially short-lived radicals) were recorded by virtue of the online monitoring of nESI mass spectrometry (MS). Subsequently, the dynamic information of substrates, intermediates and products were examined. Therefore, the mechanism of photocatalytic [3+2] cycloaddition reactions between phenols and olefins was proposed. This work not only enlarges the application of microdroplet synthesis, but also would provide a possible perspective for accelerating photocatalytic reactions and mechanism examinations.

By simple microwave irradiation, a high-throughput, single-step, rapid but controllable synthesis of stable colloidal CsPbX3 perovskite NCs with tunable properties and morphologies (nanocubes, nanorods, nanowires, quadrate nanoplates and hexagonal nanoplates) was achieved. It was employed in a heterogeneous solid–liquid reaction system within minutes without any tedious pre-preparation.

Monitoring of electrochemical (EC) reactions is crucial to obtain efficient, fast and inexpensive reactions for synthesis or analysis. Traditional characterizations by cyclic voltammetry or spectroscopic techniques are usually limited by the lack of detailed structural information on analytes. Without any sample pretreatment, ambient mass spectrometry (AMS) can directly provide structural information of multiple analytes in situ. The monitoring of EC reactions by AMS provides potentials for detecting short-lived intermediates to examine reaction mechanisms and discover new reactions. Therefore, these developments will give significant contributions to fields including biological chemistry, electrocatalysis, organic synthesis or battery fabrication. In this review, in light of the different configurations of electrodes (e.g., rotating waterwheel electrodes and ultramicroelectrodes) for different EC reactions, various designs of EC-coupled electrospray ionization-based AMS systems are summarized. In addition, the advantages, limitations and proposed suggestions for future developments are addressed.

Visualization of Hg(II) and MeHg in their native contexts is significant for examining mercury poisoning, while it is challenging because of indistinguishable fluorescent (FL) signals during FL imaging. Herein, visualizations of mercury methylation and dynamic transformations of Hg(II) and MeHg are achieved in living biological systems. Well distinguishable FL responses (blue emission for Hg(II), yellow emission for MeHg) are obtained by a double-response FL probe (DPAHB) without any interference. As demonstrated by experimental and computational studies, the distinguishable signals are attributed to selective binding with DPAHB and different inhibition of excited-state proton transfer. Through control tests for live-dead markers, mercury methylation is demonstrated to be employed in living biological systems. Therefore, the methylation and dynamic transformations of both ions are monitored in zebrafish by imaging, and these results are confirmed by traditional high-performance liquid chromatography-based methods. The methylation of Hg(II) to MeHg, dynamic transformations and final accumulations of both species in zebrafish tissues are visualized successfully. This method is also convenient for fast evaluation of detoxification reagents. This is the first visualization of in vivo mercury methylation and dynamic transformation of both species and is effective for studying pathological processes in their native contexts.

The separating and obtaining of AIEgens with narrow-sized distribution is significant for aggregation-induced emission (AIE) examinations and applications, so far no effective pathway has been reported for separation of AIEgens with weak interactions. Here, with the aid of deflecting electric fields and accelerating electric fields, we fabricated an accelerating ambient soft-landing (AASL) as a soft separation method for accelerating and separating charged particles. By AASL, AIEgens of Cu nanoclusters (NCs) were sprayed and converted into charged particles of vapor-phase by electrospray, thereby to be selected by entering defecting electric field, then accelerated in the following accelerating electric field for the separation based on sizes, and finally landed on the receptor surface for collections. Without breaking the weak interactions between AIEgens of CuNCs, this separation can maintain the original fluorescence (FL) properties and sizes, which have been confirmed by transmission electron microscope (TEM), FL microscope, and atomic force microscope (AFM). In addition, the accumulation of uniform-sized AIEgens on the surface showed the positive correlation between AIEgens size and the landing distance, which helped to make a better collection of different size of AIEgens. This work provides a promising pathway to obtain particular monodispersed AIEgens with uniform sizes, which would be significant for further examinations and applications of AIE materials.