Water-soluble lanthanide coordination polymers particles with white-light emission and color tuning

Water-soluble polymer particles (PPs) with strong fluorescence emission were prepared from hyperbranched poly(ethylenimine) (PEI) and terpyridine-bearing aldehyde (TPy) via Schiff base reaction and self-assembly in aqueous phase. TPy/PEI PPs were then used to develop a series of luminescent lanthanide coordination polymers particles (Ln-CPPs). The optical properties of these Ln-CPPs are readily modulated over a wide spectrum in water systems. Finally, water-soluble white-emitting Ln-CPPs were achieved by controlling the lanthanide ion stoichiometry. This Ln-CPPs design approach offers a robust pathway for white-luminescent materials in water systems.

Water-soluble polymer particles (PPs) with strong fluorescence emission were prepared from hyperbranched poly(ethylenimine) (PEI) and terpyridine-bearing aldehyde (TPy) via Schiff base reaction and self-assembly in aqueous phase.

In recent decades, dynamic metal coordination polymers (M-CPs) have attracted great interest in catalysis, drug delivery, chemical sensors and bioanalysis applications.^1–7 M-CPs are constructed from metal ions and organic ligands with a variety of structures and interesting properties for many potential applications. M-CPs acting as chemical sensors are mainly explored by making use of their luminescence properties.^8–10 The luminescent M-CPs can emit a stable and intense luminescent emission, so some substances can be detected by observing changes in luminescence intensity. It is well known that lanthanide ions have high color purity and long lifetime excitation lifetime, and the emission covers the entire visible range of 400 to 700 nm. In particular, Eu(iii) and Tb(iii) ions can emit intense red and green light, respectively. Lanthanide coordination polymers (Ln-CPs) are promising luminescent materials because lanthanide ions have similar chemical properties and two or more lanthanide ions can be randomly distributed in coordination polymers with metal sites, which can modulate the color and brightness of the emission.¹¹ For the above reasons, Ln-CPs have attracted the attention of many scientists and have been effectively used to design multiple color and white light emitting materials. For example, He and co-workers¹² developed a new fluorophore that exhibits white light by combining an Eu(iii) moiety (red emission) with an organic ligand (blue and green emission). Ma et al.¹³ reported a white-light-emitting La(iii)/Tb(iii)/Eu(iii) coordination polymers based on combination of blue-emitting ligand/La(iii), green-emitting Tb(iii) and red-emitting Eu(iii) units. Song et al.¹⁴ developed a white-light-emitting compound by doping a Eu(iii) ion into the Gd(iii) framework.Meanwhile, the selection of suitable ligands plays a crucial role in the synthesis of Ln-CPs with good luminescent properties, since organic ligands can be used not only as building blocks for the construction of new backbones of Ln-CPs, but also as effective sensitizer for Ln(iii) ions.^15,16 However, ligands are generally poorly water soluble, which limits the practical sensing application in environmental and biological systems.¹⁷ An efficient strategy to promote dispersion in water is to prepare Lanthanide coordination polymer particles (Ln-CPPs) by miniemulsion method, reprecipitation method, and so on.¹⁸ Nevertheless, several drawbacks still exist for their preparation and application, such as sophisticated multistep synthetic pathways, use of environmentally unfriendly organic solvents, and the possibility of fluorescence self-quenching in aqueous solution. Therefore, the systematic investigation of water-soluble Ln-CPPs with white-light emission is quite rare. More research studies are urgently needed to accelerate the development of white-light luminescent Ln-CPPs in the water system.Based on the above considerations, we rationally designed water-soluble polymer particles with blue emission and selected Tb(iii)/Eu(iii) to construct white-light-emitting Ln-CPPs (Fig. 1). The water-soluble polymer particles were constructed from hyperbranched poly(ethylenimine) (PEI) and terpyridine-bearing aldehyde (TPy) via Schiff base reaction and self-assembly. Structural characterization and luminescence properties in the water system of Ln-CPPs are studied in detail. An important clue could be obtained from the result that Ln-CPPs constructed by terpyridine ligands can maintain their structural and luminescent properties in the water system. This research also provides a basis for realizing the controllability of water-soluble white-light-emitting Ln-CPPs in the future.Open in a separate windowFig. 1Schematic preparation of TPy/PEI PPs and Ln(III) coordination-based luminescent polymer particles (Ln-CPPs) under UV light (λ_ex = 365 nm).Synthesis of the TPy/PEI PPs is based on facile Schiff base reaction, which refers to the reaction between primary amine on PEI and aldehyde group on TPy, resulting in a product containing C N bonds. Moreover, the diluted TPy/PEI PPs solution emits blue fluorescence under a 365 nm UV lamp. Fig. 2A displays the fluorescence excitation and emission spectra of the TPy/PEI PPs solution, and the maximum excitation and emission wavelengths are 330 and 448 nm, respectively. The UV-vis absorption spectra of TPy/PEI PPs, PEI and TPy were shown in Fig. S4.^† Compared with TPy, the absorption peak at 250 nm in TPy/PEI PPs solution is weakened, which may be due to the decolorization effect caused by the formation of copolymer by TPy and PEI. In addition, the absorption peak at 335 nm in TPy/PEI PPs solution is attributed to n → π* transitions of C N bonds.^18,19 These phenomena indicated TPy/PEI PPs were a newly generated subject.Open in a separate windowFig. 2(A) Fluorescence excitation and emission spectra of TPy/PEI PPs (0.01 g mL⁻¹). (Inset) Photographs of TPy/PEI PPs under visible light and UV light of 365 nm. (B) FT-IR spectra of TPy/PEI, PEI, and TPy.The morphologies of TPy/PEI PPs were characterized by transmission electron microscopy (TEM), Fig. S5A^† is a TEM image and reveals that the TPy/PEI PPs are monodisperse spherical shape with the size distribution in the range of 26–50 nm. Formation of water-soluble nanoparticles is due to the following factors. In TPy/PEI copolymer, ample amine groups and pyridinium groups are hydrophilic, whereas Schiff base bonds are hydrophobic. As a result, the hyperbranched structure of TPy/PEI copolymer tends to fold and collapse, shrinking and self-assembling into uniform polymer nanoparticles in aqueous medium.¹⁸ Many hydrophilic groups on the surface of TPy/PEI PPs make the excellent water dispersity possible. To further explore the chemical composition of TPy/PEI PPs, we performed FT-IR spectra of PEI, TPy, and TPy/PEI PPs (Fig. 2B). Several featured vibration bands at 3284 and 1590 cm⁻¹ in PEI are associated with the stretching vibration of N–H bond, and their intensity is decreased in TPy/PEI PPs, which indicates that some amine groups have reacted with TPy. In addition, another remarkable new peak at 1630 cm⁻¹ was observed in TPy/PEI PPs, which can be assigned to the C N bond.^20–25 Meanwhile, a new peak at 8.37 ppm was observed in the ¹H NMR spectra of TPy/PEI PPs (Fig. S6^†), which can be assigned to N CH protons.²⁶ The monitoring of the aldehyde conversion into imine units can be carried out by measuring the CH̲O/CH̲ N integral ratio, and the conversion rate of the aldehyde into imine units is 69%. The estimation of the conversion rate from the ¹H-NMR spectrum agrees well with the calculation from the weighting measurements with a conversion rate of 73%. These analysis results well demonstrated the formation of Schiff base bonds between TPy and PEI.TPy/PEI PPs possess intrinsic fluorescence, good water solubility, and functional terpyridine structure unit, allowing us to incorporate the Ln(iii)-TPy coordination complexes into polymer networks. With the incremental addition of Tb(NO₃)₃ to the TPy/PEI PPs solution (2% v/v), the TPy : Ln ratio is 2 : 1, which produces green-luminescent Ln-CPPs, GL CPPs (τ = 0.35 ms, Φ = 4.3%, CIE coordinates (0.27, 0.36), Fig. S7, S8 and Table S1^†). In the corresponding emission spectrum, a decrease in the luminescence intensity of the ligand centred emission band at 448 nm with the concomitant emergence of sharp bands at 489 nm, 544 nm, 583 nm, and 622 nm was observed (Fig. S7^†). A decrease in the luminescence intensity of the central emission band of the ligand was observed. These emission bands were assigned to ⁵D₄–⁷F₆, ⁵D₄–⁷F₅, ⁵D₄–⁷F₄, and ⁵D₄–⁷F₃ based transitions, respectively, for Tb(iii).^27–30 A similar procedure was observed upon addition of Eu(NO₃)₃ to the TPy/PEI PPs solution with the occurrence of five characteristic Eu(iii)-based emission bands having maxima at 579 nm (⁵D₀–⁷F₀), 592 nm (⁵D₀–⁷F₁), 617 nm (⁵D₀–⁷F₂), 649 nm (⁵D₀–⁷F₃), and 687 nm (⁵D₀–⁷F₄), resulting in a clear red-luminescent Ln-CPPs, RL CPPs (τ = 0.81 ms, Φ = 11.3%, CIE coordinates (0.52, 0.29)). These emission spectra demonstrate that Ln³⁺ (Eu³⁺ or Tb³⁺) ions were successfully doped to the TPy/PEI PPs. More importantly, strong fluorescence could still be detected even after these Ln-CPPs were stored for over a week, implying that the coordination between the TPy/PEI PPs and Ln³⁺ ions is very stable. The interactions between the TPy/PEI PPs and Ln³⁺ ions were further monitored by FT-IR spectroscopy (Fig. S9^†). Strong absorbent bands at 3256, 1549 and 1398 cm⁻¹ in TPy/PEI PPs are attributed to the stretching vibrations of N–H bond.^18,19 After the formation of RL CPPs, GL CPPs or WL CPPs using Ln³⁺ ions, a dramatically red shift appeared, which indicated the coordination of the TPy/PEI PPs to Ln³⁺ ions. The medium-to-weak bands at 760 cm⁻¹ for RL CPPs, 769 cm⁻¹ for GL CPPs and 765 cm⁻¹ for WL CPPs are observed as additional evidence of the Ln–N formation.³¹Next we investigated how to modulate the emission of polymer particles by adjusting the stoichiometry of the two lanthanide chromophores. Titration of the Tb/Eu molar ratio resulted in a series of Ln-CPPs with a broad spectrum of emission under UV irradiation (Fig. 3A). By testing the emission spectrum (Fig. 3B and C), it was found that the intensity of the green band at 544 nm increased gradually at the expense of the intensity of the red band at 616 nm as a function of Tb/Eu molar ratio. Interestingly, an intense white-luminescent Ln-CPPs, WL CPPs (CIE coordinates (0.33, 0.34)), were observed when the Eu/Tb molar ratio was 1 : 4. The smart illumination control strategy here provides a simple design approach for broad-spectrum color adjustment of luminescent polymer materials.Open in a separate windowFig. 3Luminescence tuning: (A) photographs of Ln-CPPs under UV irradiation, corresponding CIE coordinates are mentioned below; (B) emission spectra (λ_ex = 330 nm) of Ln-CPPs and (C) Job''s plot showing the peak emission intensity of the red band at 544 nm and green band at 616 nm as a function of the Tb/Eu molar ratio (1 : 1, 2 : 1, 3 : 1, 4 : 1, 5 : 1, 6 : 1, 7 : 1, and 8 : 1).In conclusion, we created polymer particles with blue emission from PEI and TPy via Schiff base reaction and self-assembly under mild conditions. The structural characterization and the fundamental properties of the TPy/PEI PPs have been studied. Because of the specific structure, the TPy/PEI PPs exhibit excellent water solubility. Furthermore, we have used the TPy/PEI PPs to develop a series of luminescent Ln-CPPs with Eu(iii), Tb(iii), and mixed Eu(iii)/Tb(iii) in aqueous medium. The individual Ln-CPPs exhibited bright red (Eu-CPPs) and green (Tb-CPPs) fluorescence upon exposure to UV light (λ_ex = 365 nm). Careful tuning of the stoichiometric ratio of Eu(iii) and Tb(iii) helped in achieving water-soluble white-emitting Ln-CPPs, which could offer a suitable pathway for preparing white-luminescent materials in water systems. Due to their stability in water, in our next work efforts will be focused on exploring their potential applications in biological and environmental areas as luminescence sensing and quantitative detection materials.     

Synthesis and properties of porous CLEAs lipase by the calcium carbonate template method and its application in biodiesel production

In this work, porous cross-linked enzyme aggregates (p-CLEAs) were synthesized by the in situ co-precipitation method using CaCO₃ microparticles as templates. The preparation procedure involved the immobilization of crude lipase as CLEAs via precipitation with ammonium sulfate and entrapping these lipase molecules into the CaCO₃ templates, followed by DTT (dithiothreitol)-induced assembly of lipase molecules to form lipase microparticles (lipase molecules were assembled into microparticles internally using disulfide bonds within the lipase molecules as the molecular linkers and stimulated by dithiothreitol); finally, the removal of CaCO₃ templates was performed by EDTA to form pores in CLEAs. The scanning electron microscopy analysis of p-CLEAs showed a porous structure. p-CLEAs showed obvious improvement in thermal stability (after incubation at 65 °C, p-CLEAs lipase retained 86% relative activity, while free lipase retained only 33.67%) and pH stability (p-CLEAs relative activity was over 90% while for free lipase, the relative activity ranged from 72% to 89% from pH 6 to 9) than free lipase and could hold relatively high activity retention without activity loss at 4 °C for more than six months. The application of p-CLEAs in producing biodiesel showed a higher degree of conversion. The conversion of fatty acid methyl ester (FAME) was 89.7%; this value was higher by approximately 7.4% compared to that of the conventional CLEAs under the optimized conditions of a methanol–oil molar ratio of 6 : 1, with a p-CLEAs lipase dose of 20% and water content of 3% at 45 °C for 24 h. The FAME conversion remained greater than 70% even after reusing the p-CLEAs lipase for 8 reactions. The results demonstrated that the p-CLEAs lipase is suitable for applications in the preparation of biodiesel.

Porous cross-linked enzyme aggregates (p-CLEAs) were synthesized. This p-CLEAs presented a complete structure with abundant channels, large specific surface and more efficient catalytic effect compared with conventional CLEAs.     

大麻素受体1型基因多态性对利拉鲁肽治疗早期2型糖尿病患者临床疗效的影响研究

背景　利拉鲁肽在Ⅲ期临床试验中被证实可以有效降低糖尿病患者血糖水平,然而在临床应用过程中利拉鲁肽的降糖效果仍存在较大的个体差异。研究表明,基因多态性是造成众多药物出现个体差异的原因之一。目的　大麻素受体1型基因（CNR1）在糖尿病及其并发症中发挥重要作用,本研究旨在探讨CNR1多态性对利拉鲁肽治疗早期2型糖尿病（T2DM）患者临床疗效的影响。方法　选取2016年3月-2018年10月河南省直第三人民医院内分泌科收治的230例早期T2DM患者作为研究对象。患者均皮下注射利拉鲁肽进行治疗,治疗16周后测量体质指数（BMI）、空腹血糖（FPG）、餐后2 h血糖（2 hPG）和糖化血红蛋白（HbA1c）。另外,收集患者外周血及部分患者新鲜外周血标本分别用来进行CNR1基因1260G>A位点的基因分型及CNR1 mRNA的表达测定。结果　治疗16周后患者BMI、FPG、2 hPG、HbA1c水平均低于治疗前（P<0.05）。230例患者CNR1基因1260G>A位点的基因分型为：GG型188例（81.7%）,GA型39例（17.0%）,AA型3例（1.3%）,最小等位基因频率为0.098,三种基因型分布频率符合哈迪温伯格平衡（P=0.550）。治疗16周后,GA/AA型患者BMI、FPG、HbA1c水平均低于GG型（P<0.05）。GG型和GA/AA型患者治疗16周后BMI、FPG、2 hPG、HbA1c水平均低于治疗前（P<0.05）。125例具有合适标本的CNR1 mRNA表达分析显示,GG型患者CNR1 mRNA表达水平高于GA/AA型患者（P<0.05）。不同基因型患者恶心呕吐、低血糖及总体不良反应发生率比较,差异均无统计学意义（P>0.05）。结论　利拉鲁肽在早期T2DM患者治疗中安全有效。CNR1基因1260G>A位点的GA/AA型可能通过影响该基因mRNA的表达进而影响利拉鲁肽对T2DM患者的疗效。     

Electro–opto–mechano driven reversible multi-state memory devices based on photocurrent in Bi0.9Eu0.1FeO3/La0.67Sr0.33MnO3/PMN-PT heterostructures

A single device with extensive new functionality is highly attractive for the increasing demands for complex and multifunctional optoelectronics. Multi-field coupling has been drawing considerable attention because it leads to materials that can be simultaneously operated under several external stimuli (e.g. magnetic field, electric field, electric current, light, strain, etc.), which allows each unit to store multiple bits of information and thus enhance the memory density. In this work, we report an electro–opto–mechano-driven reversible multi-state memory device based on photocurrent in Bi_0.9Eu_0.1FeO₃ (BEFO)/La_0.67Sr_0.33MnO₃ (LSMO)/0.7Pb(Mg_1/3Nb_2/3)O₃-0.3PbTiO₃ (PMN-PT) heterostructures. It is found that the short-circuit current density (J_sc) can be switched by the variation of the potential barrier height and depletion region width at the Pt/BEFO interface modulated by light illumination, external strain, and ferroelectric polarization reversal. This work opens up pathways toward the emergence of novel device design features with dynamic control for developing high-performance electric–optical–mechanism integrated devices based on the BiFeO₃-based heterostructures.

The mutual interaction between polarization switching, light and piezoelectric strain.     

The broad-spectrum and ultra-sensitive detection of zeranol and its analogues by an enzyme-linked immunosorbent assay in cattle origin samples

Zeranol (α-zearalanol) has been used as a growth promoter in livestock since 1969 in some non-EU countries; the residues of zeranol and its five analogues in animal origin foods may endanger human health due to their strong estrogenic and anabolic activities. Therefore, it is urgent to establish simple, rapid, real-time, broad-spectrum and high-sensitivity detection methods for the residues of zeranol and its analogues. In this study, an ultrasensitive indirect-competition enzyme-linked immunosorbent assay (ic-ELISA) was established for the rapid multi-residue detection of zeranol and its five analogues in cattle origin samples, which was based on a broad-spectrum monoclonal antibody (mAb) that specifically bound to zeranol and its analogues with high sensitivity. The half maximal inhibitory concentration (IC₅₀) values for zeranol, β-zearalanol, zearalanone, α-zearalenol, β-zearalenol, and zearalenone were 0.103, 0.080, 0.161, 0.177, 0.254, and 0.194 ng mL⁻¹, respectively, the recovery rates of cattle origin samples spiked with zeranol ranged from 79.2–104.2%, and the coefficient of variation (CV) values were less than 11.4%. Excellent correlation (R² = 0.9845) was obtained between the results of HPLC-MS/MS and ic-ELISA. In conclusion, the developed ic-ELISA could be employed as an ultrasensitive and broad-spectrum detection method for monitoring trace ZEN residues in cattle origin foods.

This paper presents a broad-spectrum and ultra-sensitive ic-ELISA method for the rapid detection of zeranol and its analogues in cattle origin samples.     

Adsorption of mercury(ii) from water by a novel sPAN fiber containing sulfhydryl,carboxyl and amino groups

A novel fiber containing sulfhydryl, carboxyl and amino groups (sPAN) with high adsorption capacity for mercury was facilely prepared by chemically grafting cysteine onto a commercial polyacrylonitrile (PAN) fiber in a one-step reaction. The as-prepared sPAN was characterized for its chemical structure, thermal stability, tensile strength, surface morphology and surface binding species. The adsorption and desorption performances for mercury were investigated by both batch and dynamic experiments. The results showed that sPAN was effective for mercury removal over pH 4–7, and ionic strength produced no obvious interference with the adsorption. The equilibrium adsorption capacity of mercury could be as high as 459.3 (±16.0) mg g⁻¹, much higher than for most previously reported materials due to the strong interaction between mercury ions and sulfhydryl, carboxyl, amino groups. More than 99% adsorbed mercury could be eluted by the mixture of hydrochloric acid and thiourea, and the regenerated sPAN could be reused for mercury removal with no significant loss of adsorption capacity even after 10 cycles. The dynamic adsorption results indicated that at initial mercury concentrations of 0.1 and 1.0 mg L⁻¹, the residual mercury concentration was less than 1 μg L⁻¹, which could meet the criterion for drinking water. Moreover, at an initial mercury concentration of 10 mg L⁻¹, the residual mercury concentration was less than 50 μg L⁻¹, which could satisfy the Chinese national industry water discharge standard.

A novel fiber containing sulfhydryl, carboxyl and amino groups (sPAN) with high adsorption capacity for mercury was facilely prepared by chemically grafting cysteine onto a commercial polyacrylonitrile (PAN) fiber in a one-step reaction.     

武术学校学生结核病发病情况调查分析

目的 了解武术学校学生结核病发病规律,为进一步做好武术学校学生结核病防治及管理工作提供事实依据.方法 应用X线检查对塔沟武术学校学生进行结核病筛查,并通过痰涂片抗酸杆菌检查等确诊,对2008-2011年该校学生结核病发病情况进行统计学分析.结果 该校学生最近4年共发生结核病118例,其中肺结核发病比例最高（53.39％）;其次为结核性胸膜炎（31.35％）,特别是骨结核发病率较高（11.02％）,其他部位发病率较低.结论 根据武校学生结核病发病特点,采取综合干预措施防止结核病在校园内传播.     

Latent role of in vitro Pb exposure in blocking Aβ clearance and triggering epigenetic modifications

Both β-amyloid (Aβ) catabolism and epigenetic regulation play critical roles in the onset of neurodegeneration. The latter also contribute to Pb neurotoxicity. The present study explored the role of epigenetic modifiers and Aβ degradation enzymes in Pb-induced latent effects on Aβ overproduction in vitro. Our results indicated that in SH-SY5Y cells exposed to Pb, the expression of NEP and IDE remained declined during the recovery period, accompanied with abnormal increase of Aβ_1-42 and amyloid oligomer. A disruption of selective global post-translational histone modifiers including the decrease of H3K9ac and H4K12ac and the induction of H3K9me2 and H3K27me2 dose dependently was also showed in recovery cells. Moreover, histone deacetylase inhibitor VPA could attenuate latent Aβ accumulation and HDAC activity induced by Pb, which might be by regulating the expression of NEP and IDE epigenetically. Overall, our results suggest sustained reduction of NEP and IDE expression in response to Pb sensitizes recovery SH-SY5Y cells to Aβ accumulation; however, administration of VPA is demonstrated to be beneficial in modulating Aβ clearance.     

Structure confirmation and thermal kinetics of the inclusion of cis-jasmone in β-cyclodextrin

In this study, inclusion complex of cis-jasmone in β-CD (β-CD-CJ) was synthesized to improve cis-jasmone stability. The structure and thermal kinetics of the inclusion complex was investigated by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). DSC studies showed that the stability of cis-jasmone after β-cyclodextrin encapsulation was improved. The dissociation kinetics of β-CD-CJ at different heating rates was studied by TG, and the activation energy E of β-CD-CJ thermal decomposition kinetic parameters was defined by Flynn–Wall–Ozawa method. The results showed that the average activation energy E was 121.16 kJ mol⁻¹.

In this study, inclusion complex of cis-jasmone in β-CD (β-CD-CJ) was synthesized to improve cis-jasmone stability.