A Facilely Synthesized Dual-State Emission Platform for Picric Acid Detection and Latent Fingerprint Visualization.

To achieve a highly efficient, dual-state emission platform for picric acid (PA) detection and latent fingerprint (LFP) visualization, flexible alkyl chains have been facilely attached to the commercial organic dye 3,4,9,10-perylenetetracarboxylic dianhydride to provide the target perylenetetracarboxylate molecules PTCA-C4, PTCA-C6, and PTCA-C12. Interestingly, all these molecules exhibited impressive fluorescence characteristics with high photoluminescence quantum yields (PLQYs) of around 93.0 % in dilute solution. Also, emissive features were observed in the solid state because close molecular packing is prevented by the alkyl chains, especially for PTCA-C6, which has a high PLQY value of 49.0 %. Benefiting from its impressive fluorescence performance in both solution and as aggregates, PTCA-C6 was used as a dual-state emission platform for PA detection and also LFP visualization. For example, double-responsive fluorescence quenching in solution was observed in PA detection studies, resulting in high quenching constants (KSV ) and also low limit-of-detection values. Furthermore, the fingerprint powder based on PTCA-C6 also presented an impressive performance on various substrates in terms of fluorescence intensity and resolution, clearly providing the specific fine details of latent fingerprints. These results demonstrate that the facilely synthesized PTCA-C6 with efficient dual-state emission exhibits great potential in the real-world applications of PA detection and LFP visualization.

Expression of concern: Intelligent nanoflowers: a full tumor microenvironment-responsive multimodal cancer theranostic nanoplatform.

Expression of concern for 'Intelligent nanoflowers: a full tumor microenvironment-responsive multimodal cancer theranostic nanoplatform' by Xunan Jing et al., Nanoscale, 2019, 11, 15508-15518, https://doi.org/10.1039/C9NR04768A.

Expression of Concern: One-pot synthesis of acid-degradable polyphosphazene prodrugs for efficient tumor chemotherapy.

Expression of Concern for 'One-pot synthesis of acid-degradable polyphosphazene prodrugs for efficient tumor chemotherapy' by Na Zhou et al., J. Mater. Chem. B, 2020, 8, 10540-10548, https://doi.org/10.1039/D0TB01992E.

Phase Interface Regulating on Amorphous/Crystalline Bismuth Catalyst for Boosted Electrocatalytic CO2 Reduction to Formate.

Electroreduction of carbon dioxide into readily collectable and high-value carbon-based fuels is greatly significant to overcome the energy and environmental crises yet challenging in the development of robust and highly efficient electrocatalysts. Herein, a bismuth (Bi) heterophase electrode with enriched amorphous/crystalline interfaces was fabricated via cathodically in situ transformation of Bi-based metal-phenolic complexes (Bi-tannic acid, Bi-TA). Compared with amorphous or crystalline Bi catalyst, the amorphous/crystalline structure Bi leads to significantly enhanced performance for CO2 electroreduction. In a liquid-phase H-type cell, the Faraday efficiency (FE) of formate formation is over 90% in a wide potential range from -0.8 to -1.3 V, demonstrating a high selectivity toward formate. Moreover, in a flow cell, a large current density reaching 600 mA cm-2 can further be rendered for formate production. Theoretical calculations indicate that the amorphous/crystalline Bi heterophase interface exhibits a favorable adsorption of CO2 and lower energy barriers for the rate-determining step compared with the crystalline Bi counterparts, thus accelerating the reaction process. This work paves the way for the rational design of advanced heterointerface catalysts for CO2 reduction.

Bimetallic Metal-Organic Frameworks: Enhanced Peroxidase-like Activities for the Self-Activated Cascade Reaction.

Metal-organic frameworks (MOFs) are significant useful molecular materials as a result of their high surface area and flexible catalytic activities by tuning the metal centers and ligands. MOFs have attracted great attention as efficient nanozymes recently; however, it is still difficult to understand polymetallic MOFs for enzymatic catalysis because of their complicated structure and interactions. Herein, bimetallic NiFe2 MOF octahedra were well prepared and exhibited enhanced peroxidase-like activities. The synergistic effect of Fe and Ni atoms was systematically investigated by electrochemistry, X-ray photoelectron spectrometry, (XPS) and in situ Raman techniques. The electrons tend to transfer from Ni2+ to Fe3+ in NiFe2 MOFs, and the resulting Fe2+ is ready to decompose H2O2 and generate ·OH by a Fenton-like reaction. After integration with glucose oxidase (GOx), which can downgrade the pH value and generate H2O2 by oxidation of glucose, a self-activated cascade reagent is therefore established for efficiently inducing cell death. The changes of cell morphology, DNA, and protein are also successfully recorded during the cell death process by Raman spectroscopy and fluorescence imaging.

Continuous phase regulation of MoSe2 from 2H to 1T for the optimization of peroxidase-like catalysis.

Nanozymes are a new generation of artificial enzymes that address the limitations of natural enzymes, with numerous reports on the development of high performance nanozymes for various applications. Herein, the phase regulation of network-like MoSe2 from the metal 1T phase to semiconductor 2H phase was achieved under different reaction conditions by a facile but efficient microwave-assisted solvothermal method. The coexisting 1T/2H-MoSe2 with edge enriched and defective nanostructures showed great enhancement of the peroxidase-like properties. This high enzymatic activity may arise from optimized active sites of 1T/2H-MoSe2, effectively leading to a rapid charge transfer within the substrate. In addition, chitosan functionalization not only greatly improves the dispersion stability of MoSe2, but also significantly increases its peroxidase-like activity, probably due to its enhanced affinity to hydrogen peroxide (H2O2). Based on these results we have established a highly sensitive colorimetric assay for the detection of H2O2 and glucose in human serum.

Acid-Responsive and Biologically Degradable Polyphosphazene Nanodrugs for Efficient Drug Delivery.

To enhance the therapeutic effects and reduce the damage to normal tissues in cancer chemotherapy, it is indispensable to develop drug delivery carriers with controllable release and good biocompatibility. In this work, acid-responsive and degradable polyphosphazene (PPZ) nanoparticles were synthesized by the reaction of hexachlorotripolyphosphonitrile (HCCP) with 4-hydroxy-benzoic acid (4-hydroxy-benzylidene)-hydrazide (HBHBH) and anticancer drug doxorubicin (DOX). The controlled release of DOX could be realized based on the acid responsiveness of acylhydrazone in HBHBH. Experimental results showed that polyphosphazene nanoparticles remained stable in the body's normal fluids (pH ∼ 7.4), while they were degraded and controllable release of DOX in an acidic environment such as tumors (pH ∼ 6.8) and lysosome and endosome (∼5.0) in cancer cells In particular, the doxorubicin (DOX)-loading ratio was fair high and could be tuned from 10.6 to 52.6% by changing the dosing ratio of DOX to HBHBH. Meanwhile, the polyphosphazene nanodrugs showed excellent toxicity to tumor cells and reduced the side effect to normal cells both in vitro and in vivo due to their enhanced permeability and retention (EPR) effect and pH-sensitive degradation properties. Therefore, the constructed pH-sensitive drug delivery system has great potential for cancer chemotherapy.

One-pot synthesis of acid-degradable polyphosphazene prodrugs for efficient tumor chemotherapy.

In order to improve the therapeutic efficacy and reduce the side effects of anticancer drugs, stimuli-responsive and biodegradable drug-delivery systems have attracted significant attention in the past three decades. Herein, we report acid-responsive and degradable polyphosphazene nano-prodrugs synthesized via a one-pot cross-linking reaction of 4-hydroxybenzhydrazide-modified doxorubicin (BMD) with hexachlorocyclotriphosphazene (HCCP). The phenol groups in the as-synthesized BMD exhibited a high reactivity towards HCCP and in the presence of a basic catalyst the determined drug loading ratio of the nanoparticles, denoted as HCCP-BMD, was up to 85.64%. Interestingly, the hydrazone bonds in BMD and the skeleton of polyphosphazene tended to break down in acidic environments, and the antitumor active drug DOX was found to be released in an acidic tumor microenvironment (pH ∼ 6.8 for extracellular, and pH ∼ 5.0 for endosomes and lysosomes). The resulting HCCP-BMD prodrug exhibited high cytotoxicity to HeLa cells and could effectively suppress tumor growth, with negligible damage to normal tissues. We therefore believe that this acid- degradable polyphosphazene prodrug may offer great potential in various biomedical fields.

Intelligent nanoflowers: a full tumor microenvironment-responsive multimodal cancer theranostic nanoplatform.

Although the collaborative therapy of chemotherapy (CT) and photodynamic therapy (PDT) is much more efficient for tumor treatment than monotherapies, premature leakage of drugs from nanocarriers and hypoxia in the tumor microenvironment (TME) result in systemic toxicity and suboptimal therapy efficiency. To overcome these limitations, we developed an intelligent nanoflower composite (termed FHCPC@MnO2) by coating functionalized polyphosphazene on superparamagnetic Fe3O4 nanoclusters and then growing MnO2 nanosheets as an outer shell. The FHCPC@MnO2 nanoflowers with multistage H2O2/pH/GSH-responsive properties could fully exploit TME characteristics, including supernormal glutathione (GSH) levels, low pH and high H2O2, to realize the specific release of drugs in tumors and maximum synergetic therapeutic effects. The MnO2 nanosheets can elevate O2 concentration by catalytic decomposition of H2O2 and can be simultaneously reduced to Mn2+ by overexpressed GSH in the acidic TME. Meanwhile, the inner polyphosphazene containing (bis-(4-hydroxyphenyl)-disulfide) is GSH- and pH-sensitively biodegradable to release the anticancer drug curcumin (CUR) and photosensitizer chlorin e6 (Ce6) in the TME. Therefore, the "triple-responsive" and synergetic strategy simultaneously endows the nanoflowers with specific drug release, relieving hypoxia and the antioxidant capability of the tumor and achieving significant optimization of CT and PDT. In addition, the resulting Mn2+ ions and Fe3O4 core enable in vivo T1/T2 magnetic resonance imaging (MRI), while the released Ce6 can simultaneously provide a fluorescence imaging (FL) function. Unsurprisingly, the intelligent nanoflowers exhibited remarkable multimodal theranostic performance both in vitro and in vivo, suggesting their great potential for precision medicine.