This work presents a fully integrated potentiometric sensing platform based on laser-induced graphene (LIG) for potentiometric detection of Na+, K+, and Ca2+ in aqueous samples. The lack of a stable, miniaturized reference electrode is addressed by developing a plasticizer-free polyvinyl butyral-ionic liquid (PVB-IL) reference electrode. Strong binding between PVB and the ionic liquid was confirmed by computational analysis based on Density Functional Theory. The PVB-IL reference exhibited a potential drift of less than 1.2 mV over 12 h without the need for internal filling solutions or chloride-based redox couples. Moreover, electrochemically deposited gold nanoparticles (AuNPs) on LIG increased the interfacial capacitance from 0.36 to 1.58 mF/cm² (4.4-fold) and mitigated pressure-induced potential fluctuations when the electrodes were operated in flow-through mode, which is advantageous for continuous monitoring. The integrated sensor array, housed in a 3D-printed flow cell, exhibited near-Nernstian responses (58.57, 58.42, and 28.50 mV/dec for Na+, K+, and Ca2+, respectively), low drift (<2 mV over 12 h), and excellent agreement with ion chromatography for real river water analysis (relative errors <8%), laying the ground for a robust and field-deployable ion-sensing platform.

Intensity-based fluorescence imaging suffers from spectral overlap and optical background interference. As an alternative, fluorescence lifetime measurements on the nanosecond level are also largely constrained. Herein, we propose phase-sensitive detection of photoswitchable probes containing naphthopyran and fluorescent donors. The method features reaction kinetics in the millisecond-to-second regime, allowing frequency domain detection with cost-effective equipment. A phase shift (A )) in the fluorescence of the probes is extracted by fast Fourier transform, establishing a dependence on the molar ratio of donor to acceptor. Thus, A is proposed as a self-referencing quantity for selective highlighting of fluorescent probes and a dynamic signal readout in chemical sensing. Phase-sensitive detection of protamine, a polycationic protein often used as a neutralizer of the anticoagulant heparin during surgery, is successfully realized based on the platform.

Dynamic monitoring of different chemical species at the subcellular level greatly enriches our understanding of various biochemical processes. Hypochlorous acid (HClO), an indispensable disinfecting weapon in immune responses, is synthesized from chloride ions (Cl−) with the enzyme myeloperoxidase (MPO) in lysosomes. Here, we reported a dual-functional fluorescent nanosensor (NS_Cl&HClO) to simultaneously monitor the subcellular dynamics of HClO and Cl− in lysosomes. Prepared by nanoprecipitation from biocompatible polymers, NS_Cl&HClO contained a Cl− sensitive dye (Q+), a HClO reactive dye (Cy5), and a reference dye (LRed). Spectral separation ensured no cross-response between the two analytes. The nanosensors exhibited a detection limit of ca. 21 nM for HClO and responded to Cl− in a dynamic range of 0 to 170 mM, with excellent selectivity over a range of other reactive species and common biological ions. The dynamics of HClO in the lysosomes of RAW264.7 cells was successfully monitored by the endocytosed NS_Cl&HClO with high contrast, indicating that the proposed nanosensors are very promising for the detection of subcellular Cl− and HClO.

A visible light responsive photoswitch promising for the chemical sensing of fluoride and hydroxide anions.

Copper is an essential element in living organisms and the monitoring of copper ions in aquatic environments and biological systems is of great significance. Inspired by a family of visible light responsive photoswitchable compounds, we report here a fluorescent probe (HTI-Q) for Cu2+ with excellent selectivity, high sensitivity, and a limit of detection (LOD) of ca. 0.02 mu M. While the central carbon-carbon double bond of HTI-Q is photoisomerizable between the Z and E configurations, it is locked upon binding with Cu2+ into the E configuration, resulting in a large bathochromic shift (102 nm) and ratiometric fluorescence changes. Different sensing modes were demonstrated including in mixed solvents, a two-phase sensing system containing cation exchanger, and fluorescent nanoprobes containing a reference dye. The absorbance change of HTI-Q upon 470 nm light illumination also depended on the concentration of Cu2+. HTI-Q-based sensors were successfully applied to determine Cu2+ in real water samples with excellent recovery. Further, fluorescent nanoprobes incorporating HTI-Q were successfully applied to image endolysosomal Cu2+ changes upon external stimulation.

Polymersome-based ion-selective nano-optodes are proposed for the first time as optical nanosensors for calcium, sodium, and potentially other varieties of ions.

We report photoswitchable fluorescent hemithioindigos (HTIs) where the metastable E isomers were stabilized by the proton-bridged intramolecular hydrogen bond. Titration experiments and computational analysis indicated that the E isomers were much more basic than the Z isomers, which enabled photoactivated colorimetric and fluorescent pH response in solvents and polypropylene films. The HTIs exhibited reversibly switchable fluorescence with the Z isomers being the most fluorescent. Moreover, the HTIs were lysosomotropic and the kinetic fluorescence evolution during photoswitching was able to differentiate subcellular compartments with different pH. The combination of photoenhanced basicity, switchable fluorescence, and proton-coupled photochromism lay the groundwork for a broad range of chemical and biological applications.

AbstractChemotaxis, the directed movement caused by the concentration of certain chemicals, is ubiquitous in biology and ecology, and has a significant effect on pattern formation in numerous biological contexts (Hillen and Painter 2009; Maini et al. 1991).

The optical background such as autofluorescence and light scattering poses a big challenge to quantify nucleic acids with conventional fluorescence-based methods. We report here high-contrast nucleic acid detection with photoswitch-mediated fluorescence resonance energy transfer (FRET), which strongly occurs between the open forms of the photoswitch (a naphthopyran) and the signal fluorophores brought to the surface of the nanoprobes (≲15 nm). The fluorescence change (ΔF) upon UV irradiation is highly sensitive and more robust to quantify the target DNAs than traditional intensity measurements. Therefore, the method works in samples with strong background fluorescence from the unbound fluorophores. The photoswitchable nanoprobes could be easily prepared and interrogated in capillaries for high-throughput measurements. The method was evaluated in both sandwich-like hybridization and DNA label-free detection with a nucleic stain SG. Without DNA amplification and sample pretreatment of blood serum, the photoswitchable nanoprobes provided a limit of detection of 0.5 nM, which is ∼6 to 20 times lower than conventional FRET.

Multicolor microbeads are widely used in flow cytometry for various cellular and immunoassays. However, they are limited by their large size of around one to tens of micrometers. Nanomaterials for multiplexed analysis are emerging as valuable tools in high-throughput assays and fluorescence cell barcoding. We present barcoding and related cellular studies based on mass-produced organosilane-derived multifunctional nanospheres with a uniform size. Functional groups including thiols, amines, and azides were integrated in one step from various organosilanes without additional orthosilicates. Fluorescent nanobarcodes (NBs) were achieved through flexible physical adsorption and chemical ligation of spectrally separated fluorescent dyes. Live cells labeled with the NBs were readily distinguished by flow cytometry. The NBs have a small and uniform size (ca. 27 nm in diameter), excellent biocompatibility, rapid cellular uptake, and low dye leakage. The fluorescent nanospheres were applied for long-term cell tracking during multiple rounds of cell division and monitored over 48 hours. While most nanospheres were endolysosome-targeting, modification with fluorescein isothiocyanate (FITC) surprisingly lighted up the cell nucleus. This work lays the foundation of a unique family of functional nanomaterials promising for multiplex detection and other chemical and biological applications.

Compared with conventional water-soluble fluorescence probes, pH-sensitive fluorescent nanosensors based on hydrophobic indicators remain largely unexplored. We report here the unique pH response of the nanosensors with a hydrophobic indicator (Ch3, a Nile Blue derivative) in polymeric nanoparticles (NPs). At the aqueous-organic interface of the NPs, spectral overlap and dye accumulation caused significant Förster resonance energy transfer (FRET) not only between the protonated and deprotonated Ch3 (hetero-FRET), but also between the protonated and deprotonated Ch3 themselves (homo-FRET). The pH response was simulated according to an interfacial response mechanism and the dynamic range was found to depend on the size of the NPs and dye distribution (Kp). Therefore, adjusting the size of the NPs and the local dye concentration gave rise to a series of dynamic sensing ranges with apparent pKa values from 2.7 to 9.6 based on a single indicator. The nanosensors were successfully delivered to HeLa cells to monitor subcellular pH values in the endosomes and lysosomes. Based on cellular calibrations, the average pH in the organelles were determined to be ca. 4.7. Moreover, the pH neutralization process during lysosome membrane permeabilization (LMP) induced by hydrogen peroxide stimulation was also successfully visualized with the nanosensors.

Ammonium functionalized anion exchange silica precursor (AESP) is synthesized by 3-(2-Aminoethylamino) propyltriethoxysilane and (2, 3-epoxypropyl) trimethylammonium chloride. Then the corresponding series of membranes based on pyridine functionalized polyvinyl alcohol (PVA-Py) with varying AESP content are prepared using sol-gel method. Obtained membranes show ion exchange capacities (IEC) ranging from 0.54 mmol.g(-1) to 0.92 mmol.g(-1), but the opposite trend of water uptakes (WU) from 123.97% down to 69.09% because of the formation of organic-inorganic network. The hybrid membranes also exhibit good thermal stability (>140 degrees C), excellent mechanical properties (25.37 MPa) and high OH- conductivity (9.63 x 10(-2) S.cm(-1), 80 degrees C). Compared with the commercial Nafion (R)-117 membrane, the prepared hybrid membrane performs a much lower methanol permeability (7.57 x 10(-8) cm(2).s(-1) for prepared membrane, 2.00 x 10(-6) cm(2).s(-1) for Nafion (R)-117 membrane, 3 M methanol solutions, 30 degrees C). Only 10.7% decreases in OH- conductivity can be observed in 6 M 80 degrees C NaOH solutions after 360 h immersions, exhibiting excellent alkaline stability. The highest peak power density of the single cell with 5 M KOH + 3 M methanol fuel is 52.56 mW.cm(-2) at 80 degrees C and 0.2 MPa O-2.

A dual functional nanoprobe Pd-Q+@PDMS was proposed to simultaneously monitor Cl- and O2, leading to the determination of an average Cl- concentration of 85.7 ± 5.5 mM in lysosomes of HeLa cells. Mimicking ischemic conditions, the cells exhibited a luminescence change corresponding to a decreasing subcellular Cl- concentration.

将具有共轭结构的吡啶盐接枝在聚乙烯醇(PVA)基质上,制备出吡啶基团功能化的PVA-FP阴离子交换膜.N元素分析测得该系列膜最大取代度为10.4％(No.3膜);吡啶基团的引入将膜的初始热降解温度提高了近32℃;吡啶基团的线性分布提高了OH-离子的迁移效率;70℃时No.3膜表现出最高的OH-离子电导率(3.02×10-2 S/cm),分别将其浸泡在2 mol/L、4 mol/L、6 mol/L的KOH溶液中进行耐碱稳定性测试,未见电导率下降,升高碱液浓度至8 mol/L,其电导率在120 h后稳定在初始值的88％左右,表现出优异的耐碱稳定性能.

Geminal-imidazolium-type ionic liquid ([DimL] [OH] ILs) was synthesized. Then, a series of membranes (PVAFP/[DimL] [OH]) was prepared with pyridine functionalized poly(vinyl alcohol) (PVA-FP) as the polymer matrix. Characteristic results reveal that crystallinity of the aforementioned membrane was effectively reduced, the initial thermal degradation temperature was elevated 87 degrees C than that of unmodified PVA-GA membrane. And the maximum OH- conductivity is 5.8 x 10(-2)S. cm(-1) at 70 degrees C, only 4.6% decline of OH- conductivity can be observed after immersing it in 1 M KOH solution for 240 h, and only 13.1% decline under 6 M KOH solution was used. Besides, methanol permeability (1.1-5.1) x 10(-6 )cm(2).s(-1) was lower than that of Nafion (R) 117 (4.5-9.2) x 10(-6) cm(2).s(-1) at 30 degrees C. Finally, a peak power density of 48 mW cm(-2) at 70 degrees C can be obtained under a single cell test.

A new Gemini basic morpholine ionic liquid (IL, [Nbmd]OH) was synthesized with morphline, bromodecane and 1,4-dibromobutane via a two-step procedure. The structure of the new IL was characterized by H-1-NMR and FTIR. A series of anion exchange membranes (PVA-FP/[Nbmd]OH) were prepared by casting method with pyridine functionalized poly(vinyl alcohol) as the polymer matrix. The PVA-FP/[Nbmd]OH composite membranes were characterized in details by AC-impedance spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and tensile strength test. The results indicated that PVA-FP/[Nbmd]OH composite membranes have uniform morphology, and the introduction of pyridine groups enhance the thermal stability and alkali resistance of PVA matrix, due to the formation of the hyper conjugation structure between sigma bond (C- H bond in methyl group) and pi-bond conjugated region (pyridine group), therefore enlarging the conjugated region, decreasing the positive charge density of the cations. Meanwhile, [Nbmd]OH ionic liquid not only provided more cationic active sites but also reduced the crystalline of the composite membranes, resulting in an increase of OH- conductivity and an improvement of the mechanical properties. When the weight ratio of [Nbmd]OH to PVA was 2.5, the thermal decomposition temperature of the composite membrane was 75 degrees C higher than that of the pristine PVA membrane; the maximum OH- conductivity was found at about 4.42 x 10(-2) S.cm(-1) at 70 degrees C; no obvious decrease in OH- conductivity was observed for the composite membrane after immersing in 6 mol/L KOH solution at 80 degrees C. On the contrary, the OH- conductivity was improved to 1.6 times of the initial OH- conductivity after 400 h immersion time, showing an excellent alkali resistance stability. In addition, the methanol permeability of the composite membrane determined using 3 mol/L methanol solution at 30 degrees C was only about 2.5% - 5% of the commercial Nafion (R)-117 membrane under the same test conditions, indicating a promising potential use in alkaline direct methanol fuel cells.

A series of semi-interpenetrating network (semi-IPN) anion exchange membranes (QCS/St-G8-2-8, Quaternized chitosan/styrene-[maleic alkylene group diethyl bis (octyl dimethyl chloro/bromide), abbreviated as G8-2-8] were prepared via in-situ polymerization by Styrene (St) and G8-2-8 in QCS casting solution. During the process of in-situ polymerization, linear block polymers (St-G8-2-8) of Styrene and G8-2-8 was constructed, then was mixed with QCS casting solution, followed crosslinking the QCS by glutaraldehyde (GA). With the increasing content of linear block polymer, water uptake and swelling ratio of the composite membrane decreased; This kind of linear structure makes an order arrangement of quaternary ammonium groups which improves the OH− migration efficiency. At 70 °C, the M-30 composite membrane performs a high OH− conductivity of 8.20×10-2 S·cm-1, the methanol permeability is 3.23×10-6 cm-2·s-1 which is still lower than Nafion 115 of 2.42×10-6 cm-2·s-1, but M-30 shows a higher selectivity of 25.3 than Nafion 115 of 11.6. Furthermore, the membranes exhibited excellent thermal stability (≥150 °C), the tensile strength of the composite membrane is in the range of 14-25 MPa and elongation at break is in the range of 16-37 % at room temperature, as well as superior chemical stability in 1.0 M KOH solution for 250 h.

A gemini-type basic morpholine ionic liquid ([Nbmd][OH]) was synthesizedviaa two-step method with morpholine, bromododecane and 1,4-dibromobutane as raw materials, and its structure was characterized by1H NMR and FT-IR spectroscopy.

Increasing environmental pollution caused by toxic dyes due to their hazardous nature is a matter of great concern, and lacks the effective methods to remove them. Therefore, in this research a series of H(3)O(40)PW(12/)Quaternized chitosan (PWX%/QCS) membrane catalyst is synthesized based on QCS (positively charged) and keggin-type H3O40PW12 (negatively charged), which is available to degrade rhodamine B. The optimum experimental conditions are investigated and results reveal that the degradation rate is over 92.1% and the chemical oxygen demand (COD) decreases is 78.09%, which is obtained based on the follow conditions is that the UV radiation is 90 min, the dose of membrane catalyst is 0.1g, the doping amount PW12 (H3O40PW12) is 35 wt%, RB aqueous solution (30mL) is 5mg/L, the reaction temperature is 30 degrees C, pH = 5 and H2O2 is 20mM. The simulation result reveals that the photocatalytic degradation reaction of RB with PWX%/QCS membrane catalyst in an aqueous solution can be described by the Langmuir-Hinshelwood equation. And the initiation rate constant and the initiation adsorption constant in this case are 4.082mg/(L/min) and 0.01090L/mg, respectively.

以壳聚糖(CS)和双氰胺为原料,在一定温度下通过亲核加成合成壳聚糖双胍盐酸盐(CGH),并以三聚氰胺(MA)为交联中间体,戊二醛为交联剂制备具有全互穿结构的阴离子交挟膜(CGH-MA).对该系列膜进行了红外、热重分析以及力学性能等测试,并探讨了三聚氰胺含量对阴离子交换膜离子交换能力、导电能力以及耐碱稳定性的影响.实验结果表明,三聚氰胺含量为4％时,该膜的离子交换能力最高可达2.47 mmol/g,70℃电导率达到4.4×10-2 S/cm,该膜在60℃2 mol/LKOH溶液中浸泡192 h后,电导率未有明显变化,表现出优异的耐碱稳定性.