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Photocatalytic process represents a promising approach to overcome the pollution challenge associated with the antibiotics-containing wastewater. This study provides a green, efficient and novel approach to remove cephalosporins, particularly cefoperazone sodium (CFP). Bi4O5Br2 was chosen for the first time to systematically study its degradation for CFP, including the analysis of material structure, degradation performance, the structure and toxicity of the transformation products, etc. The degradation rate results indicated that Bi4O5Br2 had an excellent catalytic activity leading to 78% CFP removal compared with the pure BiOBr (38%) within 120 min of visible light irradiation. In addition, the Bi4O5Br2 presents high stability and good organic carbon removal efficiency. The effects of the solution pH (3.12 - 8.75) on catalytic activity revealed that CFP was mainly photocatalyzed under acidic conditions and hydrolyzed under alkaline conditions. Combined with active species and degradation product identification, the photocatalytic degradation pathways of CFP by Bi4O5Br2 was proposed, including hydrolysis, oxidation, reduction and decarboxylation. Most importantly, the identified products were all hydrolysis rather than oxidation byproducts transformed from the intermediate of β-lactam bond cleavage in CFP molecule, quite different from the mostly previous studies. Furthermore, the final products were demonstrated to be less toxic through the toxicity analysis. Overall, this study illustrates the detailed mechanism of CFP degradation by Bi4O5Br2 and confirms Bi4O5Br2 to be a promising material for the photodegradation of CFP.

Luminescent materials with aggregation-induced emission enhancement (AIEE) have received increasing attention as chemosensors. Four AIEE active imidazole derivatives with TPA moieties, M-MAP, M01-DMAC, M-IF, and M01-IF, have been developed for the sensitive detection of NAC explosives. The luminescence behaviors of compounds were systematically measured. In 90% THF/H2O, 100–200 nm aggregated nanoparticles were formed with good regularity and stability. The intramolecular free rotations were restricted and emissions were enhanced within the aggregated state. The fluorescence of aqueous AIEE dispersions showed sensitive quenching by picric acid (PA), and the LOD was determined to be 30.99 nM for M-MAP. The intermolecular PIET mechanism was responsible for recognition and sensitive detection. Moreover, their AIEE luminescence behaviors respond weakly to other nitroaromatic compounds (NACs) or analogs. The quenching efficiencies, for M-MAP and M01-MAP, were almost consistent with the risk degrees of NACs. The test strips were easily prepared and the emission quenching effect was simply observed after contacting NACs. The potential of our new AIEEs was demonstrated for the fabrication of convenient and easily operating sensors for NACs.

An applicable RNase assay was constructed based on strong luminescent complex between Thioflavin T (ThT) and RNA. The emission of ThT was more sensitive to RNA than to DNA, and electrostatic interaction played an important role when ThT interacted with RNA. The ThT-RNA fluorescence system displayed high specific quenching for RNase A, which originated from the specific cleavage reaction of RNA by RNase A. The quantitative detection of RNase A was built with a rather low detection limit 2.47 × 10−6 U/mL. Enzymatic kinetics and inhibitory experiments were conducted to demonstrate the utilities of this method in RNase A activity study and screening of enzyme inhibitors in biological samples.

It is always a challenge to achieve the selective recognition between human serum albumin (HSA) and bovine serum albumin (BSA) because of their highly homologous primary structure. In this work, we reported two red-NIR fluorescence probes, BI-FPI and NTPS-FPI, for HSA and BSA differential recognition. BI-FPI showed remarkable emission enhancement toward HSA over BSA, while NTPS-FPI exhibited the opposite selectivity toward BSA. The obvious different interaction for probes with HSA and BSA were demonstrated by site specific competitive binding experiments and molecular docking studies. BI-FPI located within site I of HSA, which mainly depended on the hydrophobic residues and π-π interaction. While NTPS-FPI docked into the interface between subdomains II and IIIA of BSA, and the strong hydrogen bond interaction was the main contributor for the binding. Furthermore, the good calibration graphs of BI-FPI to HSA enabled us to develop the attractive multiple functional probe for qualitatively and quantitatively detecting HSA, and the detection limit (0.01 μM, 0.66 mg/L) met the requirements of traditional HSA assay in serum or in urine (30 mg/L).

Multicolor mechanochromic luminescent (MCL) materials are promising candidates in fundamental science and practical applications. In this paper, a series of novel smart luminescent compounds based on a cyanostyrene unit, NAIF, NA-15C5, NAPM, NAIP and NAPF, have been developed. NAIF, NAPM, NAPF and NAIP all exhibit aggregation-induced emission (AIE) characteristics and individually show red, orange, yellow and green emission in their aggregated state. Luminogens NA-15C5 and NAPM display reversible tricolor-changing MCL behaviors. NAIF and NAIP show bicolor switching mechanochromic phenomena. Additionally, different molecular packing modes of two crystalline polymorphs, NAPM-y and NAPM-o with bright yellow and orange luminescence color, rationally explain the tricolor-changing mechanochromic mechanism. Moreover, luminogen NAIP can be used as ink-free rewritable paper.

Human serum albumin (HSA) is the most abundant protein in human blood plasma. It plays an important role in many physiological functions, and the increase or decrease of HSA can exhibit the conditions of human health. Therefore, the accurate detection of HSA with high selectivity and sensitivity has a great clinical importance. We herein developed four red-emitting benzo[ e ]indolium fluorescent dyes, L1-L4, for probing HSA in a physiological buffer or human urine. Satisfactorily, L2 and L4 showed high selectivity and excellent sensitivity for HSA in both PBS buffer and human urine. L2 was completely embedded in the α-helices from subdomain IIA (Sudlow site I) of HSA, and the limit of detection (LOD) was 13.43 mg L −1 in PBS and 8.91 mg L −1 in urine, respectively. However, L4 inserted into the α-helices from subdomain IIA and IIIA (Sudlow site II) of HSA, and exhibited a lower LOD (1.75 mg L −1 in PBS, 1.50 mg L −1 in urine). Furthermore, the high tolerance of environmental pH and anti-interference of L2 and L4 enabled us to develop the promising molecular probes for HSA.

We reported a new fluorescence probe based on Schiff base with 15-crown-5 ester, DB-15C5, which was easy to synthesize and highly specific for the sensitive determination of human serum albumins (HSA) in physiological media or human urine. DB-15C5 exhibited weak or no fluorescence in the physiological environment because of the typical twisted intramolecular charge transfer (TICT) properties, but the addition of HSA caused the fluorescence switch-on responses of DB-15C5. DB-15C5 inserted into the α-helices from subdomains IIA (Sudlow site I) and IIIA (Sudlow site II) of HSA. The crown ester core embedded in the central cavity of site I, which involved in π-π stacking interactions and H-bond. The triphenylamine group stretched into the cavity of site II and failed to freely rotate, and the TICT excited state of DB-15C5 was restricted. Good calibration graphs of the response to HSA and a notably low limit of detection (LOD) (1.7 nM in PBS, 29.5 nM in urine) enabled us to develop a potent functional molecular probe to determine the HSA content in actual biosystems, which was not affected by other proteins and coexisted ions.

The optical behaviors of three hydroxy-naphthol based Schiff bases, L1, L2 and L3, in aggregated states in 1,4-dioxane (Diox) – H2O mixture, were investigated. The intermolecular hydrogen bond between luminogen and water resulted in the twisting of benzothiazole group, which is favorable for the assembly of organic molecules into J-aggregates. And also a bathochromic shift in absorption and enhancement of the fluorescence emission (aggregation-induced enhanced emission, AIEE) can be observed. L1 and L2 in Diox-H2O mixture with water volume fractions (fw) 95% assembled into microribbons with 40–50 nm thickness, twisted together to make amorphous supramolecular organogels. Whereas L3 assembled into needle-like nanorods with the thickness up to ~200 nm, consistence with its lower emission intensity compared to L1, L2 aggregates. Moreover, a drastic blue-shift and an enhancement of emission efficiency of L1-L3 were also observed in solid states with the morphology change from the crystalline to the amorphous state by grinding. It was found that L1 aggregates showed fluorescence switch-off sensing towards Cu2+, with higher selectivity and sensitivity compared to L1 in Diox solution.

A novel near-infrared (NIR) emitting cyanine dye, 2-[4-N,N-diphenylaminostyryl] -β-naphthothiazolium propylsulfonate (N3), has been newly developed. N3 exhibits striking size-dependent aggregation-induced emission (AIE) characteristic in DMSO/H2O mixtures with water fractions (fw) > 70%. The formation of nanoparticles is advantageous for fluorescence emission, while larger size agglomeration leads to a reduction. In solid, N3 shows crystal-induced emission enhancement (CIEE) and its NIR emissive behavior is morphology-dependent. The brightly emissive crystalline powder (λem = 687 nm) (ON state) is transformed into non-emissive amorphous state (OFF state) when grinding. The smart fluorescent ON-OFF properties can be reversibly tuned by grinding and heating or solvent fuming. Possible strategies to construct the physical sensor for pressure or temperature, chemosensor for volatile organic compounds (VOCs), as well as the technology for data storage are disclosed.

The novel core-shell polymersomes with sustained and pH-responsive drug delivery properties is developed in this work. Doxorubicin hydrochloride (DOX) loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles were prepared as a core, and then modified with polymer shells through electrostatic assembly. Three polymers, amino-terminated poly (ethylene glycol)-folate (NH2-PEG-FA), poly (allylamine hydrochloride) (PAH) and quaternary chitosan (QCS) were selected for constructing the shell layer. The successful modifications of polymer shell on the spherical DOX@PLGA core were characterized by SEM, TEM, particle size and zeta-potential. It was verified that DOX was well dispersed in core of polymersomes. In vitro drug release studies showed that DOX@PLGA core performed well in acidic pH triggered drug release. The core-shell polymersomes, especially for DOX@PLGA@PEG-FA, can be used to form pH-sensitive systems for smart and sustained drug release. FA, as the targeting agent, was exposed onto the polymersomes surface, possible for interacting with folate receptors on many cancer cells membranes. Fitted experimental data with various kinetic models, the drug release mainly follows the Fickian diffusion mechanism in the polymer system, and the erosion mechanism only existed at acidic pH. All the presented results make the proposed polymersomes a promising system for controlled and selected drug delivery.

Two novel Boron-fluorine derivatives bearing dimethylamino moieties, BOPIM-1 and BOPIM-2, were proposed as sensitive fluorescent sensors for low-level water quantification in organic solvents. Two BOPIMs exhibit typical phenomenon for an emission from a twisted intra-molecular charge transfer (TICT) state, the emission red shift and intensity weakening with solvent polarity. Introduction of trace amount of water to solvent resulted in fluorescent quenching, accompanied by the red shift of the emission, which was attributed to the formation of TICT excitation of BOPIMs by hydrolysis. A quantification method to detect water content was developed, described by a linear equation lg(I/I(0)) vs. lg φ(w) in the range of φ(w) (volume fraction of water) 0.001~0.01, 0.01~0.1, respectively. The experiment results of determination of water in real 1, 4-dioxane (Diox) samples proved that this method can be used in practical application.

The red-emitting indolium derivative compound (E)-2-(4-(diphenylamino)styryl)-1,3,3-trimethyl-3H-indol-1-ium iodide (H3) was demonstrated as a sensitive membrane fluorescence probe. The probe located at the interface of liposomes when mixed showed much fluorescence enhancement by inhibiting the twisted intramolecular charge transfer state. After ultrasonic treatment, it penetrated into lipid bilayers with the emissions leveling off and a rather large encapsulation efficiency (71.4%) in liposomes. The ζ-potential and particle size measurement confirmed that the charged indolium group was embedded deeply into lipid bilayers. The probe was then used to monitor the affinities of antioxidant flavonoids for membranes. It was verified that quercetin easily interacted with liposomes and dissociated the probe from the internal lipid within 60 s under the condition of simply mixing. The assessment of binding affinities of six flavonoids and the coincident results with their antioxidation activities indicated that it was a promising membrane probe for the study of drug bio-affinities.

Five derivatives of 2, 3, 3-trimethyl-3H-indolium containing different electron donor groups (H1 - H5) were synthesized for the determination of proteins. H3, a sensitive red-emitting fluorescent probe, was found for the discrimination of hydrophobic proteins from hydrophilic. The OFF - ON fluorescence switch of H3 was caused by the formation of twisted intramolecular charge-transfer (TICT) state when it combined with hydrophobic proteins in aqueous buffer. There was a good linear relationship between the emission intensity of H3 and the casein concentration (r = 0.9989). Based on this, a novel casein quantitative assay method was developed, and the method was applied to determinate casein in milk powder samples. Successfully, the results were in good agreement with Biuret method. In addition, a simple and sensitive method was established to differentiate and quantify three casein components (α-, β-, and κ-casein) due to their much different binding constants to H3 probe.