Coupling Bifunctional Nanozyme-Mediated Catalytic Signal Amplification and Label-Free SERS with Immunoassays for Ultrasensitive Detection of Pathogens in Milk Samples.

Rapid and sensitive detection of foodborne bacteria is of great significance in guaranteeing food safety and preventing foodborne diseases. A bifunctional Au@Pt core-shell nanozyme with excellent catalytic properties and high surface-enhanced Raman scattering (SERS) activity was developed for the highly sensitive detection of Salmonella typhimurium based on a label-free SERS strategy. The ultrathin Pt shell (about 1 nm) can catalyze Raman-inactive molecules into Raman-active reporters, greatly amplifying the amount of signal molecules. Moreover, the Au core serves as an active SERS substrate to enhance the signal of reporter molecules, further significantly improving the detection sensitivity. Benefiting from the excellent properties, such a bifunctional Au@Pt nanozyme was integrated with a magnetic immunoassay to construct a label-free SERS platform for the highly sensitive detection of S. typhi with a low detection limit of 10 CFU mL-1. Also, the Au@Pt-based SERS platform exhibited excellent selectivity and was successfully utilized for the detection of S. typhi in milk samples by a portable Raman spectrometer. Our demonstration of the bifunctional nanozyme-based SERS strategy provides an efficient pathway to improve the sensitivity of label-free SERS detection of pathogens and holds great promise in food safety, environmental analysis, and other biosensing fields.

Efficient entry point encoding and decoding algorithms on 2D Hilbert space filling curve.

The Hilbert curve is an important method for mapping high-dimensional spatial information into one-dimensional spatial information while preserving the locality in the high-dimensional space. Entry points of a Hilbert curve can be used for image compression, dimensionality reduction, corrupted image detection and many other applications. As far as we know, there is no specific algorithms developed for entry points. To address this issue, in this paper we present an efficient entry point encoding algorithm (EP-HE) and a corresponding decoding algorithm (EP-HD). These two algorithms are efficient by exploiting the m consecutive 0s in the rear part of an entry point. We further found that the outputs of these two algorithms are a certain multiple of a certain bit of s, where s is the starting state of these m levels. Therefore, the results of these m levels can be directly calculated without iteratively encoding and decoding. The experimental results show that these two algorithms outperform their counterparts in terms of processing entry points.

Variation of topologies and entanglements in metal-organic frameworks with mixed tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide and dicarboxylate ligands.

Six metal-organic frameworks with the combination of a novel tripodal ligand tris[4-(1H-imidazol-1-yl)phenyl]phosphine oxide (tipo) and different polycarboxylates, namely [Zn2(bpdc)2(tipo)(H2O)]·5H2O (1), [Cd(tipo)2][Cd2(bdc)3]·4H2O (2), [Cd2(ndc)2(tipo)2]·3H2O (3), [Cd2(bpedc)2(tipo)2]·15H2O (4), [Cd2(hfdc)2(tipo)2]·10H2O (5) and [Ni2(tipo)2(bpedc)(H2O)4]·2NO3·2DMF (6), were synthesized and structurally characterized. Compound 1 featured a 2D → 3D parallel polycatenation of a 3,3,4-connected net with an unusual 4 degrees of catenation and an index of separation of 2. Compound 2 showed an unprecedented polycatenation of charged networks 2D kgd and 3D pcu constructed by different organic ligands. Compound 3 exhibited a combination of a 2D → 3D parallel polycatenation of the sql net and polythreading. Compound 4 featured a 4-fold interpenetration of a 3,5-connected 3,5T1 net. Compound 5 displayed an unusual 2-fold interpenetration of the sdd net. Compound 6 presented a 2-fold interpenetration of the 3,4-connected bey net with a cationic framework. The luminescence properties of 1-5 in the solid state were investigated. Also, compound 6 showed a tendency for rapid selective dye capture and highly efficient Cr2O72- removal from aqueous solution.

Cyclodextrin-modified microemulsion electrokinetic chromatography for separation of alpha-, gamma-, delta-tocopherol and alpha-tocopherol acetate.

Different forms of tocopherols, together with tocotrienols, are collectively named as vitamin E, and each possesses different degree of medical, biological and physiochemical significance. The main difficulty of separating different forms of tocopherols lay in their highly structural similarities and hydrophobicities. Microemulsion electrokinetic chromatography (MEEKC), claimed to attain high peak efficiency with great solubilization power, has not previously been applied to the separation of tocopherols. The effects that various parameters, such as buffer system, type and concentration of cyclodextrins, temperature, and sample matrix, have on the separation of tocopherols by MEEKC have been investigated. By using a buffer mixture of 4% (w/w) sodium dodecyl sulfate (SDS), 6.6% (w/w) 1-butanol, 0.8% (w/w) n-octane, 20% (w/w) 2-propanol, 68.6% (w/w) phosphate (25mM, pH 2.5), and 25mM heptakis(2,6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD), the separation of alpha-, gamma-, and delta-tocopherol, alpha-tocopherol acetate, as well as the antioxidant butylated hydroxytoluene (BHT) at -26kV, 25 degrees C was completed within 35min. The practical potential of the present approach has been further validated by the determination of tocopherols in a vitamin E preparation, with the result of 132.63 (RSD 1.25%), 176.51 (RSD 0.29%), and 64.32mg (RSD 3.34%) per 500mg capsule for alpha-, gamma- and delta-tocopherol, respectively.

Micellar electrokinetic chromatography for separation of a mixture of coptis alkaloids, scute flavonoids, and rhubarb anthraquinones and bianthrones.

Coptidis Rhizoma, Scutellariae Radix, and Rhei Rhizoma are three common Chinese herbs. There are many herbal formulas which contain either two or all three of the herbs mentioned above. Their bioactive components have already been identified, respectively. However, there is no report about separation of the 13 bioactive constituents of the three herbs at the same time. In order to assess these constituents of related Chinese herbal preparations, a micellar electrokinetic chromatography method was developed. While buffer pH and surfactant concentration affected the resolution of separation, acetonitrile percentage was found to significantly influence the resolution, peak shape, and elution window. Optimum separation of 13 compounds was achieved at pH 7.3 using a buffer mixture of 70% (v/v) 3 mM di-sodium tetraborate, 10 mM sodium dihydrogen phosphate, and 50 mM sodium deoxycholate with 30% (v/v) acetonitrile. When applying the developed method to analyze a model preparation, San-huang-xie-xin-tang, which contains all three herbs, 8 of the 13 bioactive constituents, could be determined. The present study proposed a method to assess San-huang-xie-xin-tang within short analysis time and also provided a possible starting point to evaluate related herbal preparations containing Coptidis Rhizoma, Scutellariae Radix, and Rhei Rhizoma.

Effects of calcineurin inhibitors on sirolimus pharmacokinetics during staggered administration in renal transplant recipients.

STUDY OBJECTIVE: To compare the effects of different calcineurin inhibitors on sirolimus pharmacokinetics during long-term, staggered administration in kidney transplant recipients. Design. Randomized, open-label, parallel-group trial. SETTING: A medical center and one of its teaching hospitals in Taiwan. PATIENTS: Twenty-two de novo kidney transplant recipients. INTERVENTION: Patients received cyclosporine microemulsion or tacrolimus capsules twice/day in combination with once-daily sirolimus solution and corticosteroids. Sirolimus was administered 6 hours after the morning dose of cyclosporine or tacrolimus. After receiving a 6-mg loading dose of sirolimus, participants received sirolimus 2 mg/day for at least 7 days. Neither the cyclosporine nor the tacrolimus dosage was adjusted for at least 3 days before and during blood sampling for pharmacokinetic profiling. MEASUREMENTS AND MAIN RESULTS: One patient dropped out because of trimethoprim-sulfamethoxazole-related hepatotoxicity. We observed no differences between the two patient groups in terms of their demographic data, renal and liver function, or dosage of sirolimus during the study. During multiple-dose administration, the area under the whole-blood concentration-time curve and the peak and trough concentrations of sirolimus in the cyclosporine group were, respectively, 1.46 (95% confidence interval [CI] 1.21-1.71), 1.42 (95% CI 1.08-1.76), and 1.42 (95% CI 1.09-1.76) times higher than those of the tacrolimus group, even though sirolimus was administered 6 hours after the other agents. CONCLUSION: Sirolimus pharmacokinetics may change significantly when calcineurin inhibitors are switched, even with staggered administration, which may not completely prevent a drug interaction between cyclosporine and sirolimus solution.

Analysis of rhubarb anthraquinones and bianthrones by microemulsion electrokinetic chromatography.

In this work a method of microemulsion electrokinetic chromatography (MEEKC) has been developed for the analysis of nine anthraquinones and bianthrones in rhubarb. This study employed di-n-butyl tartrate as oil substance to make up the microemulsion. The composition of the microemulsion was 0.5% (w/w) di-n-butyl tartrate, 0.6% (w/w) SDS, 1.2% (w/w) 1-butanol and 97.7% (w/w) 10 mM sodium borate buffer, pH of the buffer being 9.2. Acetonitrile was added to the emulsion to improve the separation. The volume ratio between the emulsion solution and acetonitrile of an optimized separation was 70:30. With the optimized conditions all of the nine analytes were baseline-separated in peaks of good shapes within 20 min. After validation the method was used to analyze the components in a rhubarb sample. A solid-phase extraction procedure was employed. Five anthraquinones and two bianthrones had been detected in the sample and their amounts were determined. The method should be able to be used for the quantitative analysis of the main active components of rhubarb crude drugs.

Sensitivity improvement on detection of Coptidis alkaloids by sweeping in capillary electrophoresis.

A simple and rapid sweeping method for the online improvement of detection sensitivity of the main alkaloids of Coptidis Rhizoma has been developed in this work. Optimum separation conditions were found as follows: electrophoretic running solution comprising 100 mM phosphoric acid, 15 mM sodium dodecyl sulfate (SDS) and 10% (v/v) tetrahydrofurane with pH 1.82; running voltage of -25 kV; sample matrix composed of 50 mM phosphoric acid and sample injection at 1000 mbar for 60 s (sample injection volume ca. 2.75 microl). With this sweeping method, the concentration limits of detection of berberine, coptisine and palmatine were found to be 2.5 ppb (ng/ml), which was about 500 times lower than those from conventional sample injections. Baseline separation was achieved for the main alkaloids within 15 min. After validation, the developed method was applied to determine the quantity of berberine, coptisine and palmatine in a Coptidis Rhizoma sample. The method should be able to be used in identification and quantitative evaluation of the crude drugs requiring only a minor amount of sample.

Effects of conversion from sirolimus oral solution to tablets in stable Taiwanese renal transplant recipients.

BACKGROUND AND PURPOSE: Sirolimus (SRL) has a considerable inter- and intra- individual variability in clearance. Steady-state trough concentration (C(0)) is a reliable index of SRL exposure. This study assessed the effect of conversion of SRL oral solution to tablet form on C(0) in stable renal transplant recipients. METHODS: Twenty two stable renal transplant recipients who had received calcineurin inhibitor (CNI)/SRL solution/ steroid for more than 3 months before conversion from SRL solution to tablets were included. C(0) values of SRL were compared for the periods of use of each dosage form. The relation between liver function and SRL levels was also assessed. RESULTS: With a dose of 0.03 mg/kg/day, SRL solution and tablets achieved a similar dose-adjusted C(0) (mean +/- SEM, 2.9 +/- 0.3 ng/mL/mg) upon conversion. Similar results were found when multiple SRL C(0) values from different dosage form periods were compared. Four patients with persistent liver enzyme elevation had significantly higher dose-adjusted SRL C(0) values with both the solution (mean +/- SEM, 4.5 +/- 0.7 vs 2.3 +/- 0.1 ng/mL/mg; p < 0.01) and the tablet formulation (4.0 +/- 0.5 vs 2.6 +/- 0.2 ng/mL/mg; p < 0.05). CONCLUSIONS: Conversion from SRL solution to SRL tablets did not significantly affect the dose-adjusted SRL C(0). The dose-adjusted C(0) of SRL in patients with persistent liver enzyme elevation was significantly higher than in those with normal liver function.

Electrophoretic behavior and pKa determination of quinolones with a piperazinyl substituent by capillary zone electrophoresis.

Electrophoretic behavior and pKa determination of six quinolones with a piperazinyl substituent, together with two quinolones without a piperazinyl substituent and 1-phenylpiperazine, were investigated by capillary zone electrophoresis. The results indicate that quinolones with a piperazinyl substituent involve three protonation/deprotonation equilibria. The results also suggest that the contribution of the zwitterionic species of these quinolones to the effective mobility may not be neglected. This is probably due to a slightly incomplete protonation of the piperazinyl moiety in the pH range of 6.0-8.0, compared with the complete dissociation of the carboxylic group. Consequently, the zwitterionic species of ciprofloxacin, in particular, is slightly negatively charged. With the aid of computer simulation, three pKa values were determined for quinolones with a piperazinyl substituent, thus allowing us to rationalize precisely the influence of pH on the electrophoretic behavior of these compounds.