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A novel ratiometric fluorescent probe for Cu2+ was fabricated in spherical polyelectrolyte brush (SPB) where the red-emission europium complex Eu(TTA)3Phen was embedded in the polystyrene (PS) core to generate the reference signal and the green-emission glutathione-capped CdTe quantum dot was immobilized onto the poly(styrene sulfonate) brush shell to provide the sensing signal. Results indicate that this probe has high sensitivity and selectivity for Cu2+ over other metal ions. The addition of Cu2+ could greatly quench the probe’s fluorescence at 550 nm, while the fluorescence signal at 614 nm kept unchanged. Under the optimized conditions, the intensity ratio of the two fluorescence emissions showed a linear response range from 0 to 1000 nM with a limit of detection of 1.45 nM for Cu2+. The probe is very suitable for the detection of copper contamination with quick response, low cost and great stability. SPB was proved to be an excellent “carrier” for building high-quality ratiometric probes due to its special core–shell structure and outstanding ability to enrich counterions. This work provides a versatile method for the development of high-quality ratiometric fluorescent probes, which can be extended to potential applications in various fields, such as environmental monitoring, biological imaging, pathological analysis and cancer diagnosis.

The stimulus-responsive drug delivery system has attracted increasing attention due to its ability to enhance therapeutic efficacy and reduce side effects. Herein, a pH and glutathione (GSH) dually responsive drug carrier, hollow silica–-polyelectrolyte composite nanoparticle, was successfully prepared by using a template of spherical polyelectrolyte brush (SPB) which consists of a polystyrene (PS) core and a densely grafted linear poly(acrylic acid) (PAA) shell. The existence of PAA chains and introduction of disulfide bonds in silica framework endow the composite nanoparticles with pH and GSH dually responsive properties which were confirmed by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). With doxorubicin hydrochloride (DOX) as the model drug, the loading content and encapsulation efficiency could reach up to 43% and 96%, respectively. The drug release behavior was investigated under various environments, showing that the drug release rate increased with the decrease in pH value and the increase in GSH concentration. The prepared hollow SiO2–PAA composite nanoparticles possess a great potential as carriers for controlled drug delivery.

Novel Mo-V-PMMA and Mo-V-PS catalysts are prepared by addition of hard polymethyl methacrylate (PMMA) and polystyrene (PS) nanospheres into Mo/V compounds in the preparation process, respectively. The catalytic tests in selective oxidation of acrolein reveal that Mo-V-PMMA catalyst shows very high acrolein conversion (99.1%) and the yield of acrylic acid (90.7%). The BET, DLS, SAXS, XRD, XPS, H 2 -TPR and NH 3 -TPD measurements reveal that the addition of PMMA and PS nanospheres causes the obvious changes of porous structure, crystal phases composition and chemical properties of catalysts. These differences between Mo-V-PMMA and Mo-V-PS catalysts are attributed to the totally different “real” nano–environment during heat treatment in the high–concentration component mixture. PS nanospheres are in a state of adhesion or agglomeration or not uniformly distributed in the active component solution, while PMMA nanospheres with much better hydrophilicity and monodispersed state promote Mo and V ions more easily and uniformly dispersed in the mixture. Graphic abstract Novel Mo-V catalysts are prepared by addition of hard polymethyl methacrylate (PMMA) and polystyrene (PS) nanospheres into Mo/V mixture. Obvious changes of porous structure, crystal phases and chemical properties of catalysts are caused by the nanospheres introduction, showing very high acrolein conversion (99.1%) and the yield of acrylic acid (90.7%) in selective oxidation of acrolein.

Nano-spherical polyelectrolyte brushes (SPBs) have been demonstrated to be versatile objects for many high-tech applications due to their unique microenvironment and impressive stability in aqueous media, showing great prospects in industry. However, the recycling of valuable SPBs is still a big obstacle, thereby limiting their industrial applications. Here, we show a facile approach to efficiently separate SPBs from aqueous latex solution on the basis of spherical poly(acrylic acid) brushes with a polystyrene core (PS-PAA brushes). Upon addition of poly(ethylene oxide) (PEO), hydrogen-bonding interpolymer complexes consisting of PS-PAA brushes and PEO are formed at pH below 3.5, leading to selective separation of the PS-PAA brushes from aqueous media containing other nanoparticles. Near all of the brushes are separated at pH below 3.0 regardless of the ion strengths. Importantly, the brushes can be easily redispersed by simply increasing pH, showing ignorable variations of the intrinsic properties like diameter, surface charge and light transmittance. As an application example, a catalytic nanoreactor is developed by loading sliver nanoparticles (Ag NPs) in PS-PAA brushes which show neglectable deteriorations of catalysis on the model reaction even after four separation–redispersion cycles. This work provides a simple way for selective separation of SPBs, which may benefit for industrial applications of SPBs.

Superhydrophobic cellulose and chitosan composite aerogel (SCECS) is fabricated through a novel and simple approach for the first time. During the preparation of cellulose and chitosan composite aerogel (CECS), chitosan is selfassemble into number micron-diameter particles on the surface of aerogel, which is similar to the micromorphology of a lotus leaf. Based on the rough surface, CECS is modified by sodium stearate through electrostatic interaction and ion exchange. Water contact angles of 156° are obtained for superhydrophobic aerogel. SCECS can remove various oils from water and with absorption capacities of 10 g/g for oil. Furthermore, the special structure of a non-porous of surface and porous layer of internal is benefit to separate surfactant-stabilized water-in-oil emulsions under gravity.

Substantial efforts are directed into exploring the structure-properties relationships of photoluminescent Carbon dots (C-dots). This study unravels a resculpting mechanism in C-dots that is triggered by electrochemical etching and proceeds via extensive surface oxidation and carbon–carbon breakage. The process results in the gradual shrinkage of the nanoparticles and can enhance the quantum yield by more than half order of magnitude compared to the untreated analogues.

Surgical excision remains the principal treatment for melanoma, while tumor recurrence and delayed wound healing often occur due to the residual tumor cells and hypoxic microenvironment in the postoperative skin wounds. Herein, we present a living photosynthetic microneedle (MN) patch (namely MA/CM@MN) loaded with microalgae (MA) and cuttlefish melanin (CM) for postsurgical melanoma therapy and skin wound healing. Benefiting from the oxygenic photosynthesis of the alive MA in the MN base, the MA/CM@MN can generate oxygen under light exposure, thus facilitating skin cell proliferation and protecting cells against hypoxia-induced cell death. In addition, with CM nanoparticles embedded in the MN tips, the MA/CM@MN can be effectively heated up under near-infrared (NIR) irradiation, contributing to a strong tumor killing efficacy on melanoma cells in vitro. Further experiments demonstrate that the NIR-irradiated MA/CM@MN effectively prevents local tumor recurrence and simultaneously promotes the healing of tumor-induced wounds after incomplete tumor resection in melanoma-bearing mice, probably because the MA/CM@MN can inhibit tumor cell proliferation, stimulate tumor cell apoptosis, and mitigate tissue hypoxia in light. These results indicate that the living photosynthetic MN patch offers an effective therapeutic strategy for postoperative cancer therapy and wound healing applications. Graphical Abstract

This paper presents a facile procedure to fabricate uniform-sized hollow silica nanoparticles (SNP) under a mild condition by using cationic spherical polyelectrolyte brushes (SPB) with a polystyrene (PS) core and densely grafted poly(2-aminoethyl methacrylate hydrochloride) (PAEMH) brush shell as a catalytic template. By changing the brush layer thickness of SPB, hollow SNP with different silica shell thickness could be easily obtained. This method provides a new way for the preparation of hollow SNP without additional catalyst. The obtained hollow SNP exhibited a high-drug encapsulation efficiency (80%) for doxorubicin hydrochloride (DOX), should be of significance in the fields of drug delivery, cancer therapy, and bioimaging.

Everlasting pursuit of the high energy efficiency as well as meeting fluctuant temperature causes various lighting requirements over the day, which is driving the demand for creating a multifunctional smart window (SW) system. Here, an upper critical solution temperature (UCST)- and/or lower critical solution temperature (LCST)-type SW system (denoted as SWU, SWL and SWU+L, respectively) was fabricated through a simple bio-inspired physical cross-link process between amorphous CaCO3 (ACC) and poly(acrylic acid) (PAA). Series of mineralized hydrogel-based chromic layers were first in situ formed by sealing the composite of ACC in PAA matrix into polyethylene terephthalate (PET) “sandwich structure” to fabricate the SW system. As expected, the SWU system exhibited a typical UCST transition process, bringing about a luminous transmittance (Tlum) of 40.70% at 25 °C and a Tlum of 74.76% at 45 °C. The high scattering of the initial state as well as large optical contrast (ΔTlum= 34.06%) of the SWU system guarantees residential privacy and energy savings. Also, a thermochromic SWL system with a relatively high luminous transmittance (Tlum) of 47.81% at 25 °C and an acceptable solar modulation property (ΔTlum= 16.06%) was constructed. A conceptual SWU+L system was fabricated, that is, a sharp UCST transition followed by a LCST process. This reversible two-stage optical switch process subsequently occurs by continuously increasing temperature, endowing this SW system highly suitable for SW or logic gate. The SW system with multi-thermo-responsiveness brings more flexibility in building facade design.

As a strong oxidizing pollutant, NO2 can cause fire or even explosion. People living in atmosphere containing NO2 for a long time will significantly affects human health. In this work, we developed a Schottky heterojunction sensor modified by g-C3N4 quantum dots (g-C3N4QDs) and rGO deposited on TiO2 nanotubes (TNTs) arrays. This sensor showed high response and extremely fast response/recovery time as well as excellent detection of ppb level of NO2 at room temperature. TNTs were obtained using a one-step anodic oxidation process. TNTs were modified with g-C3N4QDs and rGO using quasi-CVD method and cyclic voltammetry during in situ electrodeposition, respectively. TNTs/g-C3N4QDs/rGO Schottky heterojunction sensor exhibited high sensitivity to 10 ppm of NO2 (response equal to 15982) at room temperature. Below 15 ppb, sensing response also can reach 127. Sensor response was very fast and increased to 15982 in just 2 s when exposed to 10 ppm of NO2 after which it recovers 90% within 1.16 s. This work clarified the influence of abundant oxygen vacancies (VO·) in TNTs and photogenerated electrons on TNTs/g-C3N4QDs/rGO nanostructures as well as their sensing performances. Our experimental details demonstrated that Schottky barrier was established between TNTs and rGO, which was very beneficial for ppb-level NO2 detection at room temperature.