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Electronic skins (e-skins) are increasingly investigated and applied in wearable devices, but the robustness and convenient production of traditional e-skins are restricted. In this work, electrospun sandwich-structured elastic films (ESEFs) are developed and utilized as capacitive e-skins. The ESEFs consist of two nanocomposite mats as the electrode layers and a sandwiched thermoplastic polyurethane (TPU) mat as the dielectric layer. The nanocomposite mats are composed of thermoplastic polyurethane (TPU) and AgNW-bridged MXene (AgNW, silver nanowire; MXene, Ti

Hypochlorous acid (HClO), the core bactericidal substance of the human immune system, plays a vital role in many physiological and pathological processes in the human body. In this work, we designed and synthesized a novel deep-red fluorescent probe TCF-ClO for the determination of hypochlorous acid through theoretical analysis. The results showed that probe TCF-ClO exhibited excellent characteristics of long-wavelength emission (635 nm), fast response ( 1 min), and low detection limit (24 nM). In addition, it had been successfully used for imaging of HClO in living HeLa cells. More importantly, the TCF-ClO composited paper-based sensing material was successfully constructed. The RGB/gray value was obtained from a mobile phone and computer, which could achieve the quantitative detection of HClO, with a linear detection range of 0-50 μM and a detection limit of 1.09 μM (RGB mode)/3.38 μM (gray mode). The function of the paper-based sensor extended from qualitative to quantitative detection of HClO, and it is expected to become a portable device widely used in the environmental area.

Multicolor carbon dots (CDs) possess tremendous potential applications, especially in optoelectronic devices. However, further applications of multi-color LED have been constrained due to the very limited researches concerning the wavelength control mechanism of multi-color CDs. In this work, through theoretical calculation and experimental verification, the regulatory effects of sp2 conjugated domain on the fluorescence wavelength of CDs were explored. Firstly, through a regulation on the structure size and the introduction of amide bonds, four kinds of structures were designed in DFT theoretical calculation to explore the influence of sp2 conjugated domain on the fluorescence wavelength of CDs theoretically. Then, using thiourea and p-phenylenediamine as the precursors and by regulating the reaction solvents, multicolor CDs with blue, green and red fluorescence emission were prepared to experimentally verify the emission mechanism. It was confirmed that the increasing structure size and the introduction of amide bond would induce an increasing size of the sp2 conjugated domain, leading to the red shift of the CDs fluorescence wavelength. Finally, in order to suppress the self-quenching performance, the CDs@PVP fluorescent film possessing bright solid-state fluorescence was constructed for a better application in light-emitting diodes. The approach provided an effective strategy to realize the programmed regulation on the fluorescence wavelength of CDs, offering us full of potentials for the applications of CDs in the photoelectric device fields.

Polydopamine (PDA)-based self-adhesive hydrogel sensors are extensively explored but it is still a challenge to construct PDA-based hydrogels by free radical polymerization. Herein, a new approach to construct self-adhesive hydrogels by conducting free radical polymerization in both aqueous phase and micelle phase is developed. The following two-phase polymerization processes account for the formation of the self-adhesive hydrogels. The first one is the polymerization of acrylamide (AM) and dopamine (DA) in aqueous phase to form adhesive component PAM-PDA (PAM, polyacrylamide; PDA, polydopamine). The second one is the polymerization of hydrophobic monomer 2-methoxyethyl acrylate (MEA) in micelles of an amphiphilic block copolymer Pluronic F127 diacrylate (F127DA). The poly(2-methoxyethyl acrylate) (PMEA) networks help to maintain the high robustness of the hydrogel. Because PMEA and PDA form in relatively separated phases, the inhibition effect of PDA on the free radical polymerization process of PMEA is weakened. Based on this mechanism, mechanically strong and adhesive hydrogels are achieved. The introduced ions during preparation process, such as Na+, OH– and K+, endow the resulting hydrogels ionic conductivity. Resistive strain sensor of the hydrogel achieves a high gauge factor (GF) of 5.26, a response time of 0.25 s and high sensing stability. Because of the adhesiveness, such hydrogel sensor can be applied as wearable sensors in monitoring various human motions. To further address the freezing and drying problems of the hydrogels, organohydrogels are constructed in glycerol-water mixed solvent. The organohydrogels exhibit outstanding anti-freezing property and moisture retention ability, and their adhesiveness is well maintained in subzero conditions. Capacitive pressure sensors of the organohydrogels possessing a GF of 2.05 kPa−1, high sensing stability and reversibility, are demonstrated and explored in monitoring diverse human motions.

Glutathione and 2-aminopyridine are used as carbon sources to prepare carbon dots (CDs) by a one-step hydrothermal reaction. The results show that the average particle diameter of CDs is 8.64 nm with uniform size distribution and the fluorescence quantum yield is 13.62%. We further demonstrate that novel CDs possess highly selective sensing of Fe3+ from 0.2 to 200 μM with a low detection limit (0.194 μM). Meanwhile, the fluorescence of CDs can be repeated many times by the addition of S2−. Moreover, the CDs are used for biological imaging of living cells with well cell penetrability and low toxicity. Furthermore, it is successfully applied for anti-counterfeiting and information encryption. More interestingly, it can be doped with hydrogel and filter paper to prepare solid-phase sensors exhibiting high sensitivity and fast response, demonstrating their tremendous potential for the simple, rapid, and low-cost monitoring of Fe3+ and S2−.

Devising novel water-soluble carbon dots (CDs) with a facile and economical process is pivotal for the detection of ions in the environment. In this paper, novel nanoscale CDs (polyethyleneimine-2,...

Novel spherical polymer nanoparticles were synthesized by hyperbranched polyethylenimine (hPEI) and 6-hydroxy-2-naphthaldehyde (HNA) via Schiff base reaction (one-pot reaction), which had great advantages in water solubility and green synthesis. Meanwhile, probe PEI-HNA could quickly detect Cu2+ in the range of 0–60 μM in 30 s with the detection limit of 243 nM. The fluorescence of PEI-HNA-Cu2+ could be recovered by the addition of S2− in 50 s with the detection limit of 227 nM. Based on the excellent optical properties, PEI-HNA has been used in the bioimaging of living cells with excellent cell penetrability and low toxicity. More importantly, PEI-HNA has been doped into filter paper, hydrogel, and nanofibrous film to prepare solid-phase sensors, displaying rapid response and excellent sensitivity. Moreover, the low-cost and simple preparation of these sensors offers great potential and possibilities for industrialization, which could help accelerate the development of sensors in environmental and biological fields.

Self-recoverability and stretchability are critical for high-performance hydrogel sensors, but developing hydrogels with combined self-recoverability and stretchability remains a challenge. Here, s...

Highly sensitive capacitive-type pressure sensor has been achieved by fabricating reliefs on solution-processable hydrogel electrodes. Hybrid PVA/PANI hydrogels (PVA, poly(vinyl alcohol); PANI, polyaniline) with a fully physically cross-linked binary network are selected as the electrodes of the pressure sensors. On the basis of the solution processability, reliefs are fabricated on the surface of PVA/PANI hydrogel electrodes by a template method. The gauge factor (GF) is enhanced by introducing reliefs and regulated by controlling the composition and relief dimension of hydrogel electrodes. The optimized pressure sensor containing reliefs achieves the highest GF of 7.70 kPa

Compliance and low strain hysteresis are of great importance for wearable devices and electronic skins, but it is still a challenge to obtain materials with high compliance, low strain hysteresis and sensing ability for electronic skins. In this work, we have achieved highly compliant and low strain hysteresis sensory electronic skins (SESs) utilizing solution processable hybrid hydrogels. The hybrid hydrogels are constructed by incorporating polyaniline (PANI) into poly(vinyl alcohol) (PVA). By regulating the contents of PVA and PANI, the elastic modulus of the PVA/PANI hybrid hydrogels can be tuned in the range of 15.7–154.4 kPa, which covers the elastic modulus of human soft tissue (≈30 kPa). The PVA/PANI hybrid hydrogels also achieve low strain hysteresis and exhibit outstanding recovery during the cyclic loading–unloading process. In such hydrogels, PANI works as the conductive component and contributes to the conductivity of the hybrid hydrogels (13.3 S m−1). Further investigations reveal that the compliant SESs possess high sensitivity (GF = 4.28), outstanding stability (>1000 cycles) and low response time (250 ms). Because of the fully physically cross-linked structure, the hydrogels in SESs are completely solution processable and can be regenerated. By introducing glycerol into the hybrid hydrogels, the flexibility of SESs can be kept at least for one week and the sensing ability is also well maintained. Finally, we demonstrate that SESs exhibit reliable sensing ability in monitoring representative human movements, such as joint bending and swallowing.

Functionalized paper is a class of promising candidate materials for flexible electronic devices, but preparation of functional paper with multimodal sensitivity remains a challenge. Herein, functi...

Fluorescent carbon dots (CDs) have attracted considerable interest due to their superior optical properties and facile preparation. In this work, O-phenylenediamine and melamine were used as precursors for the one-step hydrothermal synthesis of novel orange emissive CDs (O-CDs) in an aqueous solution. The fluorescence intensity (580 nm) of the O-CDs exhibited a good linear relationship with Ag

Glutathione and 2-aminopyridine are used as carbon sources to prepare carbon dots (CDs) by a one-step hydrothermal reaction. The results show that the average particle diameter of CDs is 8.64 nm with uniform size distribution and the fluorescence quantum yield is 13.62%. We further demonstrate that novel CDs possess highly selective sensing of Fe

Ionogels are ideal candidate materials for flexible sensors, but their stretchability and fatigue resistance are limited. Herein, highly stretchable, fatigue-resistant, electrically conductive, and temperature-tolerant ionogels are investigated and further applied in fabricating high-performance flexible sensors. The ionogels consist of a poly(acrylic acid) (PAA) network and a commonly used room-temperature ionic liquid (RTIL) named 1-ethyl-3-methylimidazolium dicyanamide ([EMIm][DCA]). Dually acrylated Pluronic F127 (F127DA) was utilized to cross-link the PAA network, and [EMIm][DCA] was physically confined in the PAA network. Because of their special cross-linking structure, the PAA ionogels are highly stretchable (>850%), tough, and fatigue-resistant, and they are also conductive, transparent, and temperature-tolerant because of the existence of [EMIm][DCA]. On the basis of their integrated performances, the PAA ionogels were further utilized to fabricate strain sensors and pressure sensors. The ionogel-based strain sensors have high sensitivity, low response time (200 ms), wide strain-sensing range (0-750%), excellent durability (>1400 cycles), and good temperature tolerance and can be applied to detect various human motions. The pressure sensors also have a high response speed (256 ms) and excellent sensitivity (GF = 0.73 kPa-1), which offers an opportunity to detect force generated by finger touching and water droplets.

In this study, a novel near-infrared fluorescent off-on probe for H2S based on seminaphthorhodafluor fluorophore is designed and constructed, which could be used in detection with 121-fold (23-fold) fluorescent (absorbance) enhancement at 630 nm (572 nm), fast responsiveness (completed within 5 min), high sensitivity, and lower cellular autofluorescence interference. Based on these excellent optical properties, the probe was employed to monitor H2S in red wine samples with satisfactory results. Moreover, the probe was successfully applied for monitoring and imaging H2S quantitatively in Hela cells and live athymic nude mice, indicating its potential application in biological science.

Click chemistry is an effective tool to fabricate three-dimensional gel network in an accurate way. In this work, Pluronic F127 gels are prepared by thiol–ene click chemistry, utilizing double-bond end-capped Pluronic F127 (F127DA) and pentaerythritol tetras-mercaptopropionate (PETMP) as the starting materials and triethylamine as the catalyst. Both the mass fraction of F127DA and the initial concentration of PETMP have effects on the properties of the resulting F127 gels. The optimized F127 gel prepared under a F127DA mass fraction of 15 wt% and a PETMP concentration of 17.62 mmol/L exhibits the highest swelling ratio (10) and has the largest elongation at break (194%). When the F127DA mass fraction and PETMP concentration are fixed at 15 wt% and 48.26 mmol/L, respectively, the resulting F127 gel has a high stress of 0.25 MPa. The present example has presented a method to fabricate three-dimensional gel network in a controlled way.

A rhodamine-based fluorescent probe for Cu2+ and ATP has been designed. The fluorescence intensity/absorbance was significantly enhanced upon the addition of Cu2+ owning to the opening of the spiro-ring of rhodamine, which quickly returned to the original level due to the reconstruction of the probe by the reacting with ATP. Cu2+/ATP-induced fluorescent intensity/aborbance changes showed a good linear relationship with the concentration of Cu2+/ATP in the range of 2–20 μM/0–10 μM with a detection limit of 0.1 μM/1.0 μM. The proposed method is simple in design and fast in operation, and is suitable for the reversible monitoring of Cu2+ and ATP in bioanalytical applications.

Novel spherical polymer nanoparticles were synthesized by hyperbranched polyethylenimine (hPEI) and 6-hydroxy-2-naphthaldehyde (HNA) via Schiff base reaction (one-pot reaction), which had great advantages in water solubility and green synthesis. Meanwhile, probe PEI-HNA could quickly detect Cu

Hydrogen sulfide (H

Specifically, visually, and quantitatively monitor copper ion (Cu

Influences of colloidal stabilities of nanoparticles (NPs) on the bioaccumulation of co-existing pollutants remains largely unknown. In this study, two oxidation products of nanoscale zero-valent iron (nZVI) with totally varied colloidal stabilities, termed highly oxidized nZVI (HO-nZVI) and lowly oxidized nZVI (LO-nZVI), were exposed to zebrafish with chromium (Cr); this approach was used to investigate the impacts of colloidal stability of oxidized nZVI on the bioaccumulation of Cr in zebrafish. A significant increase in the Cr and NP content in the viscera of fish in the presence of the oxidized nZVI after 20 days of exposure was confirmed, which indicated that Cr was consumed by fish through the uptake of the NPs. Furthermore, a significantly higher level of the HO-nZVI accumulated in the viscera in contrast to LO-nZVI, which suggested that the colloidal stability of NP is a crucial factor when evaluating the accessibility of NPs to zebrafish. Thus, HO-nZVI induced a significantly stronger enhancement of Cr content in fish than LO-nZVI. Our results suggest that oxidized nZVI will act as the carrier of co-existing heavy metals and change the transportation and distribution of heavy metals in zebrafish; moreover, the colloidal stability of NP will have a significant influence on the bioaccumulation of coexisting Cr.

Although soft electronic materials are of significant importance for flexible electronic devices, most of them are derived from commercial polymer elastomers, such as polydimethylsiloxane, polyurethane and Ecoflex. In this work, citric acid-based degradable polyester elastomers are prepared by a melt polycondensation process, utilizing citric acid, 1,8-octanediol and poly(ethylene glycol) (PEG) as monomers. Furthermore, poly(1,8-octanediol citrate acid) (POC)-PEG/silver nanowire (AgNW) conductive polyester elastomers (CPEs) are prepared by introducing a AgNW layer on the surface of the POC-PEG films. Scanning electron microscopy images reveal that the thickness of the AgNW layer is on the scale of several micrometers and the AgNWs form a continuous conductive network. Upon mechanical stimuli, POC-PEG exhibits recoverable deformation and induces variation in the AgNW conductive network, resulting in a conversion of strain to detectable resistance. When tensile strain is applied, the POC-PEG/AgNW CPEs achieve a gauge factor of 231.6, a response range of 0%-50%, a low response time of 35 ms and high stability. Moreover, the POC-10PEG/AgNW CPE also responds to bending deformation with a gauge factor of 3667.5, a response range of 0%-8.4%, a low response time of 62 ms and high stability. On the basis of strain sensitivity, wireless sensors are further assembled by integrating the POC-PEG/AgNW CPEs into a Bluetooth signal transmission system. Various human motions and physiological activities are successfully monitored using the wireless sensors. The results demonstrate that degradable citric acid-based polyester elastomers/AgNW CPEs are promising materials for next-generation sustainable and flexible electronic devices.

A reversible fluorescein-based fluorescent probe which exhibits high sensitivity and selectivity for Zn2+ and ATP, has been designed and synthesized. The sensing process was completed via fluorescence variation induced by an opening and closing of the spiro-ring of fluorescein. Zn2+/ATP-induced fluorescent intensity shows a good linear relationship with the concentration of Zn2+/ATP in the range of 0–10 μM with a detection limit of 0.1 μM/0.5 μM. Moreover, the probe was further applied to visualize and detect Zn2+and ATP in vitro and in vivo.

This work describes the preparation, characterization and removal capability of a novel biomass derived carbonaceous sponges (CS) and their nanocomposites. The CS has hierarchically porous structure which is composed of lamellar structures and secondary porous structures. The pore size is on a scale from 1 nm to 200 μm. Utilizing the CS as adsorbents, rapid removal of model organic molecules, including methylene blue (MB), methyl orange (MO) and crystal violet (CV), from their aqueous solutions can be completed within 1 min with the assistance of pressure and the removal efficiency reaches up to 100%, 81% and 98%, respectively. The removal capabilities for CS towards MB, MO and CV are 0.0769 g/g, 0.2218 g/g and 1.0384 g/g, respectively and 0.0635 g/g, 0.0977 g/g and 0.8634 g/g, respectively for CS nanocomposites.

Flexible strain sensors are highly used in soft robotics, human–machine interfaces and health monitoring devices. However, it is still a big challenge to construct strain sensors with excellent mechanical properties and broad sensing ranges. In this study, a class of extremely stretchable and electrically conductive hydrogels with dually synergistic networks are fabricated for wearable resistive-type strain sensors. Dually synergistic networks are composed of a soft poly(acrylic acid) (PAA) network and a rigid conductive polyaniline (PANI) network. The PAA network is crosslinked by amphiphilic block copolymers, and the PANI network is chemically doped and ionically crosslinked by phytic acid and these two networks are further interlocked by physical entanglements, hydrogen bonds and ionic interactions. The resulting hydrogels have high tensile strength, controllable conductivity and large tensile deformation (1160%). Moreover, these hydrogels are utilized for fabricating strain sensors with good sensitivity and a wide sensing range (0–1130%). The high performances of hydrogels make such strain sensors suitable for wearable devices monitoring both subtle and large strains induced by human motions, including moving of two hands, bending of joints, conducting of gestures and swallowing.

In this work, a series of novel fluorescent probes based on the fluorophores 3-benzothiazolyl-7-hydroxycoumarin/7-hydroxycoumarin were developed for detection of H2S. The probes exhibited excellent specific responses to H2S over other related competing species, including reactive sulfur, nitrogen and oxygen species. Moreover, the further successful imaging of the targetable fluorescent probe for sensing H2S in vivo was exciting and revealed that this targetable probe could serve as an efficient tool to study H2S-related chemical biology in physiological and pathological events.

Stretchable and elastic double network (DN) hydrogels are increasingly investigated for flexible electronics but their recyclability is rarely considered. Herein, recyclable, stretchable and conductive DN-hydrogels are explored and utilized in flexible resistive-type strain sensors. Such DN-hydrogels are fully physically cross-linked and composed of a crystalline domain cross-linked poly(vinyl alcohol) (PVA) network and a Tb3+-cross-linked poly(acrylic acid sodium) (PAANa–Tb3+) network. Due to their unique structure, DN-hydrogels have excellent recyclability and flexibility, and they are also conductive and photoluminescent due to the presence of Tb3+. Utilizing DN-hydrogels, flexible strain sensors are assembled and further applied to monitor large human motions, such as moving of two hands and bending of joints, as well as subtle physiological activities including moving of the bicipital muscle, swallowing and breathing. Overall, the present example not only helps to understand the toughening and strengthening mechanism of fully physically cross-linked DN-hydrogels, but also offers a clue to develop multifunctional hydrogels for recyclable flexible electronics.

Fluorescent carbon dots (CDs) have attracted considerable interest due to their superior optical properties and facile preparation. In this work, O-phenylenediamine and melamine were used as precursors for the one-step hydrothermal synthesis of novel orange emissive CDs (O-CDs) in an aqueous solution. The fluorescence intensity (580 nm) of the O-CDs exhibited a good linear relationship with Ag+ in the range of 0.0–50.0 μM with the detection limit of 0.289 μM. Moreover, the O-CDs were successfully used to determine Ag+ in biological samples (Hela cells) because of their low cytotoxicity, and good biocompatibility. Besides, the O-CDs-doped solid-phase detection materials (test paper and hydrogel) were employed to monitor Ag+ qualitatively and quantitatively, indicated that the O-CDs had a great capacity for the detection of Ag+ in biological and environmental areas. Based on their extraordinary fluorescence property, the O-CDs could also be used as security ink. Overall, based on their excellent fluorescent performance, the CDs in this study have significant potential for practical application toward solid-phase sensing and security ink.

Hydrogen sulfide (H2S) played crucial roles in biological processes and daily life, and the abnormal level of H2S was associated with many physiological processes. In this paper, we designed and developed a dicyanomethylene-4H-chromene (DCM)-based near-infrared (NIR) fluorescent probe DCM-NO guided by theoretical calculation. The probe displayed excellent selectivity towards H2S with a fast response time (3 min) and low detection limit (fluorescence 25.3 nM/absorption 6.61 nM) in Hela cells and real water samples. Furthermore, the probe-doped solid sensing materials (test strips and nanofibrous films) exhibited specific visualization of H2S under ambient light or hand-held UV lamp, providing great potential for on-site and real-time application in environmental and biological systems.

Developing heterogenous detection technology for Cu2+ is of great significance, which has great merits of recyclability, easy operation, and environmental friendliness. However, the construction of a solid-state sensor with fast response and high efficiency is hard to achieve. Herein, highly dispersed and water-soluble fluorescent PEI-EAS nanoparticles (PEI-EAS NPs) with a diameter of ~10 nm were firstly synthesized, which showed high-efficient and reversible detection of Cu2+ in aqueous and biological system (Hela cells). More importantly, three kinds of composites based on PEI-EAS NPs and test paper (PEI-EAS@TP), hydrogel (PEI-EAS@HG) and nanofiber film (PEI-EAS@NF) have been large-scale synthesized, achieveing the heterogeneous and reversible detection of Cu2+ in different test-environment and application area. This systematic design of outstanding solid-state Cu2+ composite probe has enlightened the development of relevant detection systems in the future.

Hydrogel-based flexible sensors are of promising applications in various fields, but fabrication of such sensors with integrated high performances remains a challenge. In this work, flexible sensors (both strain sensors and pressure sensors) with integrated high performances are fabricated utilizing double network (DN) organohydrogels. Because of the unique structure of DN organohydrogels, the flexible sensors exhibit intrinsic adhesion without introducing components that are often used to obtain adhesive hydrogels, such as polydopamine, nucleobases or proteins. In addition, outstanding temperature tolerance (−18 to 80 °C), high stretchability (>2000%), tensile strength (>300 kPa), self-healing ability (96.5%) and transparency (90%) are also achieved. Resistive-type strain sensors of DN organohydrogels achieve high gauge factor (GF = 2.58), low response time (0.18 s), large sensing range (0–1000%) and reversible sensing ability (>1000 cycles). Sandwich-shaped capacitive-type pressure sensors comprising DN organohydrogel electrodes with reliefs exhibit a high sensitivity of 2.14 kPa−1. Such flexible sensors can be applied in monitoring various human motions and subtle physiological activities and further promoted as wireless sensors on the basis of a Bluetooth protocol.

A novel fluorescein-based dual probe was designed and synthesized. The probe exhibited highly sensitive and selective colormetric response to Fe3+ and turn-on fluorescence response towards OCl− with very low detection limits of 100 and 50 nM, respectively. It was successfully applied for quantitative detection of Fe3+ and OCl− in real water samples. Moreover, probe 1 was expected to be a potentially powerful tool for studying and providing further insights into OCl− and Fe3+ chemistry in the near future.

This paper presents panoramic unmanned aerial vehicle (UAV) image stitching techniques based on an optimal Scale Invariant Feature Transform (SIFT) method. The image stitching representation associates a transformation matrix with each input image. In this study, we formulate stitching as a multi-image matching problem, and use invariant local features to find matches between the images. An improved Geometric Algebra (GA-SIFT) algorithm is proposed to realize fast feature extraction and feature matching work for the scanned images. The proposed GA-SIFT method can locate more feature points with greater accurately than the traditional SIFT method. The adaptive threshold value method proposed solves the limitation problem of high computation load and high cost of stitching time by greater feature points extraction and stitching work. The modified random sample consensus method is proposed to estimate the image transformation parameters and to determine the solution with the best consensus for the data. The experimental results demonstrate that the proposed image stitching method greatly increases the speed of the image alignment process and produces a satisfactory image stitching result. The proposed image stitching model for aerial images has good distinctiveness and robustness, and can save considerable time for large UAV image stitching.

A broad-spectrum fluorescent probe, which can be applied to monitoring H2S in various biological systems, has been rationally designed and synthesized. This specific probe was applied to localize the endogenous H2S in living Raw264.7 macrophage cells, HepG2 cells, and H9C2 cells. At the same time, the probe has successfully visualized CBS- and CSE-induced endogenous H2S production and monitored CBS and CSE activity in H9C2 cells. This probe could serve as a powerful molecular imaging tool to further explore the physiological function and the molecular mechanisms of endogenous H2S in living animal systems.

Predicting the aggregation tendency of nanoscale zero-valent iron (nZVI), oxidized nZVI, in particular, is crucial for the risk assessment of nZVI in aquatic environments. In this study, the comprehensive effects of the pH and ionic strength (IS) on the aggregation behaviors of two highly oxidized nZVIs (HO-nZVI) were examined. Compared with hematite nanoparticles, HO-nZVI presented a sudden acceleration in aggregation under critical conditions; moreover, the morphology of the HO-nZVI aggregates at pH and IS values higher or lower than the critical conditions was significantly different. Furthermore, owing to the differences in magnetization between the two prepared HO-nZVI samples, their critical coagulation conditions were significantly different. The significant changes in the aggregation behavior of the HO-nZVI samples were analyzed using colloidal theories, and the aggregation tendency of HO-nZVI under specific conditions could be simulated by calculating the theoretical critical conditions of aggregation via a method that takes into account the hydrochemical properties, magnetization, and surface charge of HO-nZVI. To examine the correctness of the method, we compared the experimentally determined colloidal stability of HO-nZVI in water samples collected from nearby rivers with the theoretically predicted value. The results indicated that the method was adequate for most situations, except for those in which the hydrochemical properties of the water samples were close to the critical coagulation conditions. Our study proposes a theoretical approach that is viable for simulating the colloidal stability of magnetic nanoparticles in aquatic environments; we anticipate that it will further facilitate the risk assessment of nanoparticles.

Herein, we presented two novel turn-on colorimetric and fluorescent probes based on a F− triggered Si O bond cleavage reaction, which displayed several desired properties for the quantitative detection for F−, such as high specificity, rapid response time (within 3 min) and naked-eye visualization. The fluorescence intensity at 574 nm (absorbance at 544 nm) of the solution was found to increase linearly with the concentration of F− (0.00–30.0 μM) with the detection limit was estimated to be 0.47 μM/0.48 μM. Based on these excellent optical properties, the probes were employed to monitor F− in real water samples and tea samples with satisfactory. Furthermore, it was successfully applied for fluorescent imaging of F− in living nude mice, suggesting that it could be used as a powerful tool to predict and explore the biological functions of F− in physiological and pathological processes.

Hydrogen sulfide (H2S) is an important endogenous gaseous signal transmitter. In this work, a novel near-infrared fluorescent probe DS for the detection of H2S was designed and synthesized based on the theoretical analysis. The optical investigation results showed that H2S could be detected quantitatively in the concentration range 0.0–10.0 μM, and the detection limit was calculated to be 9.0 nM (fluorescence intensity) and 88.2 nM (absorbance). Furthermore, probe DS was successfully applied for imaging H2S in living cells, which exhibited the admirable advantages of membrane permeability and biocompatibility. Moreover, a portable fluorescence nanofibrous film prepared by electrospinning was successfully constructed for the visual detection of H2S under the UV lamp, indicating its potential applications in the area of portable membrane sensing.