Sensitive paper-based analytical device for fast colorimetric detection of nitrite with smartphone.

On-site rapid monitoring of nitrite as an assessment indicator of the environment, food, and physiological systems has drawn extensive attention. Here, electrokinetic stacking (ES) was combined with colorimetric reaction on a paper-based device (PAD) to achieve colorless nitrite detection with smartphone. In this paper, nitrite was stacked on the paper fluidic channel as a narrow band by electrokinetic stacking. Then, Griess reagent was introduced to visualize the stacking band. Under optimal conditions, the sensitivity of nitrite was 160-fold increased within 5 min. A linear response in the range of 0.075 to 1.0 µg mL-1 (R2 = 0.99) and a limit of detection (LOD) of 73 ng mL-1 (0.86 µM) were obtained. The LOD was 10 times lower than the reported PAD, and close to that achieved by a desktop spectrophotometer. The applicability was demonstrated by nitrite detection from saliva and water with good selectivity, adding 100 times more concentrated co-ions. High recovery (91.0~108.7%) and reasonable intra-day and inter-day reproducibility (RSD < 9%) were obtained. This work shows that the sensitivity of colorless analyte detection-based colorimetric reaction can be effectively enhanced by integration of ES on a PAD. Graphical abstract Schematic of the experimental setups (left) and the corresponding images (right) of the actual portable device.

5-fluorouracil-caffeic acid cocrystal delivery agent with long-term and synergistic high-performance antitumor effects.

Aim: To explore how to transform cocrystals of the anticancer drug 5-fluorouracil (FL) with caffeic acid (CF; FL-CF-2H2O) into a nanoformulation, a self-assembly strategy of cocrystal-loaded micelles is proposed. Methods: Nanomicelles were assembled to deliver cocrystal FL-CF-2H2O with synergistic activity, and their in vitro/vivo properties were evaluated by combining theoretical and experimental methods. Result: More cocrystal was packed into the polymers due to the stronger interaction energy during micellar assembly, producing excellent cytotoxicity and pharmacokinetic behavior, especially synergistic abilities and long-term therapy. Conclusion: This case exemplifies the particular benefits of the self-assembly strategy of cocrystal-loaded micelles in keeping a delicate balance between long-term effects and high efficiency for FL, and offers a feasible technical scheme for cocrystal delivery agents for antitumor drugs.

To exemplify the feasibility of the cocrystal conversion of anticancer drug 5-fluorouracil (FL) with phenolic acid nutrient caffeic acid (CF) into a nanomicelle formulation, and further provide new options for the development of slowed-release cocrystal formulations with long-acting and synergistic antitumor effects, in this study, a cocrystalline complex of FL and CF (cocrystal FL-CF-2H₂O) was loaded into polymer PEG-PCL to successfully assemble the cocrystal nanomicelles by a self-assembly strategy. The morphology of the cocrystal nanomicelles was characterized, and in vitro/vivo properties were evaluated by combining theoretical with experimental methods. The results showed that the cocrystal nanomicelles with regular sphericity and homogeneous particle size had greater drug loading and entrapment efficiency than FL nanomicelles, which is also supported by theoretical predictions of the interaction energy between the cocrystal FL-CF-2H₂O and polymer PEG-PCL. The excellent encapsulation effects give rise to more potent cytotoxicity, better absorption and prolonged retention time in vivo. Relative to FL nanomicelles, the present cocrystal nanomicelles with synergistic antitumor abilities exhibited prominent slowed-release behavior that was more conducive to the long-term maintenance of therapeutic concentrations in vivo. The present case offers a feasible technical scheme for successful nanoformulation research on synergistic antitumor pharmaceutical cocrystals.

catena-Poly[[(2,2'-diamino-4,4'-bithiazole){µ3-cis-N-(2-carboxylatophenyl)-N'-[3-(dimethylamino)propyl]oxamidato(3-)}dicopper(II)] nitrate 0.6-hydrate].

The title complex, {[Cu(2)(C(14)H(16)N(3)O(4))(C(6)H(6)N(4)S(2))]NO(3)·0.6H(2)O}(n), is a one-dimensional copper(II) coordination polymer bridged by cis-oxamide and carboxylate groups. The asymmetric unit is composed of a dinuclear copper(II) cation, [Cu(2)(dmapob)(dabt)](+) {dmapob is N-(2-carboxylatophenyl)-N'-[3-(dimethylamino)propyl]oxamidate and dabt is 2,2'-diamino-4,4'-bithiazole}, one nitrate anion and one partially occupied site for a solvent water molecule. The two Cu(II) ions are located in square-planar and square-pyramidal coordination environments, respectively. The separations of the Cu atoms bridged by oxamide and carboxylate groups are 5.2053 (3) and 5.0971 (4) Å, respectively. The complex chains are linked by classical hydrogen bonds to form a layer and then assembled by π-π stacking interactions into a three-dimensional network. The influence of the terminal ligand on the structure of the complex is discussed.

Liposome-mediated gene transfer of endothelial nitric oxide synthase to cirrhotic rat liver decreases intrahepatic vascular resistance.

BACKGROUND AND AIMS: Nitric oxide (NO) production by endothelial nitric oxide synthase (eNOS) in sinusoidal endothelial cells is reduced in the injured liver and leads to intrahepatic portal hypertension. The present study evaluates the effects of liposome-mediated gene transfer of eNOS on the intrahepatic vascular resistance and portal venous pressure (PVP) in cirrhotic rats. METHODS: Hepatic cirrhosis was induced in male Sprague-Dawley rats by intraperitoneal injection of carbon tetrachloride (CCl(4)), whereas the control normal rats were given the same dose of peanut oil. Plasmid eukaryotic expression vector (liposome-pcDNA3/eNOS) was injected into the portal vein of CCl(4) cirrhotic rats, whereas cirrhotic controls received the same dose of naked plasmid (liposome-pcDNA3) or Tris buffer, and control normal rats received the same dose of Tris buffer. Five days after gene transfer, the levels of eNOS mRNA and protein, NO production, PVP and the changes of hepatic intrahepatic vascular resistance were investigated. RESULTS: Five days after eNOS gene transfer, the levels of eNOS mRNA, eNOS protein and NO production in cirrhotic rats increased remarkably, while hepatic vascular resistance and PVP decreased significantly in cirrhotic rats. CONCLUSION: Liposome-mediated eNOS gene transfer via intraportal injection is feasible and the increase of intrahepatic eNOS leads to a marked decrease in introhepatic vascular resistance and PVP. These data indicate that intrahepatic eNOS plays an important role in the pathogenesis of portal hypertension and gene transfer of eNOS is a potential and novel therapy for portal hypertension.

Electrokinetic stacking of electrically neutral analytes with paper-based analytical device.

Electrokinetic stacking (ES) is effective for improving sensitivity of paper-based analytical device (PAD) for charged analytes. In this paper, we successfully demonstrated ES of electrically neutral analytes on PAD, and the performance was characterized by smartphone-based colorimetry and fluorescence. Firstly, SDS from cathode reservoir stacked as a micelle band on an open paper fluidic channel by ES, and the target analyte was swept by the micelle. Meanwhile, the probes at the other side were carried by electroosmotic flow (EOF). Eventually, neutral components preloaded on the channel were concentrated as the narrow stacking band. Taking the rhodamine B as a probe, the effects of EOF, background electrolyte concentration and anionic surfactant concentration were investigated. Fluorescence detection of rhodamine B and colorimetric analysis of Sudan III demonstrated the sensitivity enhanced and its potential for the semi-quantitative test. Under the optimized conditions, fluorescence detection limit of 50 nM of rhodamine B was achieved with a linear range of 1.0-10 µM (R2 = 0.99). The colorimetric detection limit for Sudan III was 5.2 µM and the linear range was 5-40 µM (R2= 0.99). Compared with direct analysis without stacking, the signal levels of rhodamine B and Sudan III were increased by 30-fold and 6-fold, respectively. This study showed that with ES, sensitive and rapid PAD detection of electrically neutral analytes could be achieved.

One-dimensional copper(II) coordination polymers bridged both by mu-trans-oxamidates and phenyldicarboxylates: Synthesis, crystal structure and DNA binding studies.

Two new one-dimensional copper(II) polymers with formulae of [Cu(2)(H(2)O)(2)(dmapox)(ipa)(2)](n) (1) and [Cu(2)(H(2)O)(2)(dmapox)(tpa)(2)](n) (2), where dmapox, ipa and tpa stand for the dianion of N,N'-bis[3-(dimethylamino)propyl]oxamide, isophthalic acid and terephthalic acid respectively, have been synthesized and characterized by elemental analysis, conductivity measurement, IR and electronic spectral studies. The crystal structures of the two complexes have been determined by X-ray single-crystal diffraction. The structures of 1 and 2 consist of one-dimensional copper(II) coordination polymeric chain constructed both by the bis-tridentate trans-dmapox and bis-monodentate phenyldicarboxylate bridging ligands. In the two complexes, the environment around the copper(II) atoms can be described as distorted square-pyramid and the Cu...Cu separations through mu-trans-dmapox and phenyldicarboxylato bridging ligands are 5.245(5) A and 8.212(3) A for 1, 5.237(8) A and 11.171(1) A for 2, respectively. The binding properties of the two copper(II) polymers with herring sperm DNA (HS-DNA) have been investigated by using absorption and emission spectral and electrochemical techniques and viscometry. The results show that the two copper(II) complexes interact with the HS-DNA in the mode of intercalation with the intrinsic binding constants of 1.22(+/-0.2)x10(4)M(-1) and 1.45(+/-0.3)x10(4)M(-1) for 1 and 2, respectively.