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The Sonogel-Carbon-PEDOT Material: An Innovative Bulk Material for Sensor Devices
摘要： The synthesis of a new bulk material based on silicon oxide and poly-(3,4-ethylenedioxythiophene) (PEDOT), the Sonogel-Carbon-PEDOT material, is carried out. The main purpose is to obtain a bare conducting material, aided by statistical experimental design, able to be used as transducer for electrochemical devices. This new material tries also to solve out the degradation and fouling drawbacks related to PEDOT-based layer devices by simply polishing its surface in a gently way. The resulting Sonogel-Carbon-PEDOT material shows excellent electrochemical properties, renewable surface and stability by using simple, low cost, and versatile synthesis method. As far as we are concerned, this is the first time that this kind of bulk material is reported. The resulting material was characterized by different techniques: SEM, EDS and Raman spectroscopy. Sonogel-Carbon-PEDOT was also electrochemically characterized for the assessment of the electrochemical performance of the resulting sensor device. Ascorbic acid was selected as reference analyte, obtaining good sensitivity and limit of detection: 319.8 μA mM-1cm-2 and 6.42 μM, respectively, in the concentration range 0.01–3.45 mM. Furthermore, repeatability and reproducibility studies (RSD<3%), were also very satisfactory. Finally, the Sonogel-Carbon-PEDOT sensor was successfully applied to the determination of ascorbic acid in a pharmaceutical formulation and biological samples, obtaining good recovery percentage (95–105%).
关键词： electrochemical properties,sensor devices,Sonogel-Carbon-PEDOT,conducting polymers,ascorbic acid
更新于2025-09-23 15:22:29
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Peptide Nucleic Acid–Fluorescence In Situ Hybridization for Detection of Staphylococci From Endophthalmitis Isolates: A Proof-of-Concept Study
摘要： PURPOSE. Rapid identi?cation of pathogens causing endophthalmitis may improve treatment outcomes through early administration of species-speci?c medication. The current study reports a new molecular application of peptide nucleic acid–?uorescence in situ hybridization (PNA-FISH) with Staphylococcus-speci?c molecular PNA probes for the potential rapid detection of common pathogens causing endophthalmitis. METHODS. An experimental study was designed to evaluate the proof of concept at the microbiology laboratory of the Bascom Palmer Eye Institute. Stored culture-positive staphylococci endophthalmitis isolates obtained from prior vitreous samples (n ? 15), along with broth as negative controls (n ? 5) were used. Inoculum was prepared to a ?nal concentration of 1 3 105 colony-forming units/mL to ensure that the isolates were viable. Smears of samples were ?xed and hybridized using QuickFISH protocol with probes for Staphylococcus. RESULTS. With PNA-FISH technique, Staphylococcus aureus was identi?ed in 9 of 10 samples and coagulase-negative staphylococci were identi?ed in 10 of 10 samples. Detection time was 20 minutes. CONCLUSIONS. This study serves a proof of concept using a new microbial detection system with FISH probes, and may have the potential for clinical use in the rapid and accurate identi?cation of isolates from patients with endophthalmitis.
关键词： peptide nucleic acid (PNA),endophthalmitis,rapid identification,fluorescence in situ hybridization (FISH)
更新于2025-09-23 15:22:29
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TiO2 Modification with Transition Metallic Species (Cr, Co, Ni, and Cu) for Photocatalytic Abatement of Acetic Acid in Liquid Phase and Propene in Gas Phase
摘要： The commercial P25 titania has been modi?ed with transition metallic species (Cr, Co, Ni, and Cu), added by impregnation with aqueous solutions of the corresponding nitrates. The preparation procedure also includes a heat treatment (500 ?C) in argon to decompose the nitrates, remove impurities and to strengthen the metal–TiO2 interaction. The catalysts have been thoroughly characterized using N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse-re?ectance spectroscopy (UV-vis DRS) and X-ray photoelectron spectroscopy (XPS), and have been tested in the aqueous phase decomposition of acetic acid and in the gas phase oxidation of propene, using an irradiation source of 365 nm in both cases. The photocatalytic activity of the four metal-containing catalysts varies with the nature of the metallic species and follows a similar trend in the two tested reactions. The effect of the nature of the added metallic species is mainly based on the electrochemical properties of the supported species, being Cu/P25 (the sample that contains copper) the best performing catalyst. In the photodecomposition of acetic acid, all the metal-containing samples are more active than bare P25, while in the gas phase oxidation of propene, bare P25 is more active. This has been explained considering that the rate-determining steps are different in gas and liquid media.
关键词： TiO2,P25,propene,photocatalysis,acetic acid,transition metals
更新于2025-09-23 15:22:29
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Chiral Recognition of L- and D- Amino Acid by Porphyrin Supramolecular Aggregates
摘要： We report of the interactions between four amino acids lysine (Lys), arginine (Arg), histidine (His), and phenylalanine (Phe) with the J-aggregates of the protonated 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin H4TPPS. Several aspects of these self-assembled systems have been analyzed: (i) the chiral transfer process; (ii) the hierarchical effects leading to the aggregates formation; and, (iii) the influence of the amino acid concentrations on both transferring and storing chiral information. We have demonstrated that the efficient control on the J-aggregates chirality is obtained when all amino acids are tested and that the chirality transfer process is under hierarchical control. Finally, the chiral porphyrin aggregates obtained exhibit strong chiral inertia.
关键词： porphyrin,self-assembly,amino acid,circular dichroism,supramolecular chirality
更新于2025-09-23 15:22:29
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Chiral Sensing Using Circularly Polarized Luminescence of Bis (phenanthroline dicarboxylic acid) Eu(III) Complex Induced by Allosteric-type Interaction with Amino Acid Molecules
摘要： [Eu(pda)2]- and [Eu(bda)2]- (pda = 1,10-phenanthroline-2,9-dicarboxylic acid; bda = 2,2’ bipyridine 5,5’-dicarboxylic acid) have an achiral D2d structure in crystals. These complexes exhibit circularly polarized luminescence (CPL) in water containing chiral amino acids. In this work, induced CPL of [Eu(pda)2]- and [Eu(bda)2]- in water solutions containing a mixture of D- and L- amino acids were examined. Plots of glum values of the induced CPL as a function of mol-fraction of L- and D- arginine reveal that [Eu(pda2]- favors homo-association ([Eu(pda)2]--(L-arginine)2 or [Eu(pda)2]--(D-arginine)2) over hetero-association {[Eu(pda)2]--(L-arginine)?(D-arginine)}. This suggests that association of an arginine molecule induces a structural change in [Eu(pda)2]- to promote chiral selective association to another arginine, i.e., homo-allosteric association. On the other hand, the system of [Eu(pda)2]- with histidine favors hetero-allosteric association over homo-association. No allosteric effect is recognized in CPL from [Eu(bda)2]-.
关键词： allosteric effect,amino acid,lanthanide complex,circularly polarized luminescence,chiral sensing
更新于2025-09-23 15:22:29
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Dual-prism based terahertz time-domain attenuated total reflection spectroscopy and its application to characterise the hydration state of L-threonine in solution
摘要： To investigate the hydration state of amino acids, terahertz time-domain attenuated total internal reflection (THz TD-ATR) spectroscopy is often adopted to measure the complex permittivity. However, the classical THz TD-ATR spectroscopy system has only a single ATR prism and requires prism cleaning for different measuring modes, increasing the time consumed and easily introducing errors due to the changing environment. To accelerate the measurements and avoid the influence of environmental fluctuations, in this paper, we designed and built a dual-prism based THz TD-ATR spectroscopy: two ATR prisms with and without samples setting on the optical rail can be sequentially switched to optical systems for easily and rapidly collecting both sample and reference ATR spectra. According to the measurements of deionised water, the dual-prism based THz TD-ATR spectroscopy system can measure the sample complex permittivity rapidly and with high accuracy. The complex permittivity of L-threonine in aqueous solution is measured and analysed via the proposed system, and the hydration numbers of L-threonine solutions in different concentrations are quantitatively characterised. It is believed that the dual-prism based THz TD-ATR technique is a powerful tool for quickly and accurately investigating the hydration of amino acids.
关键词： Terahertz spectroscopy,Complex permittivity,Time-domain attenuated total internal reflection,Amino acid hydration
更新于2025-09-23 15:22:29
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Simultaneous quantitative analysis of indomethacin and benzoic acid in gel using ultra-violet-visible spectrophotometry and chemometrics
摘要： BACKGROUND: In order to manufacture pharmaceutical products, real-time monitoring in the manufacturing process is necessary, but large equipment cost is required to achieve it. OBJECTIVE: The aim of this research is to use ultra-violet-visible spectroscopy along with chemometrics procedure to simultaneously quantitative analysis of indomethacin (IMC) and benzoic acid (BA) in the gel during pharmaceutical manufacturing process. METHODS: The gel preparations were contained of 0.1–1.5% IMC, 0.015–0.225% BA, 2% carbopol? 941 and 95% ethanol solution. The calibration models were constructed using the partial least square regression (PLS). RESULTS: The relationships of the measured and predicted concentrations for both IMC and BA had linear plots. The developed PLS calibration models were used to monitor the IMC and BA concentrations during mixing of the gels by the planetary centrifugal and conventional mixers, respectively. IMC and BA were gradually dispersed, dissolved and completely homogeneous within 30 min by the centrifugal mixer. In contrast, IMC and BA were slowly dispersed, dissolved and completely homogeneous at more than 60 min by the conventional mixer. CONCLUSIONS: The ultra-violet-visible spectrophotometric method couples with multivariate chemometric techniques for quantitative data analysis were successfully applied for the simultaneous determination of major component IMC and trace component BA in the gel.
关键词： benzoic acid,indomethacin,partial least square regression,Ultra-violet-visible spectroscopy,process analysis technology,process monitoring
更新于2025-09-23 15:22:29
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Chlorogenic Acid Supplementation Improves Multifocal Electroretinography in Patients with Retinitis Pigmentosa
摘要： To evaluate the effect of chlorogenic acid supplementation in patients with retinitis pigmentosa, we evaluated objective change in visual function with multifocal electroretinography, along with visual acuity, visual field, standard electroretinography, and contrast sensitivity. Eighteen patients diagnosed with retinitis pigmentosa were enrolled in this prospective, non-comparative, single-arm study. Multifocal electroretinography, best-corrected visual acuity in Early Treatment Diabetic Retinopathy Study letters, total point score on visual field examination with Humphrey Field Analyzer II, electroretinography, and contrast sensitivity were measured and repeated after 3 months supplementation with chlorogenic acid. The amplitude of ring 5 was significantly higher on multifocal electroretinography after 3 months of chlorogenic acid supplementation (7.2 ± 9.5 vs 8.3 ± 10.8 nV/deg2, mean ± standard deviation, P = 0.022). There were no significant changes in the best-corrected visual acuity, total point score on Humphrey Field Analyzer, 30 Hz flicker amplitude on standard electroretinography, or contrast sensitivity. Chlorogenic acid may have a beneficial effect on the peripheral area at the margins of retinal degeneration, and should be considered as an anti-oxidant for the management of retinitis pigmentosa.
关键词： Retinitis Pigmentosa,Oxidative Stress,Chlorogenic Acid,Retinal Degeneration,Antioxidants
更新于2025-09-23 15:22:29
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Complexation of the Mycotoxin Cyclopiazonic Acid with Lanthanides Yields Luminescent Products
摘要： Cyclopiazonic acid (CPA) is a neurotoxin that acts through inhibition of the sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA). CPA blocks the calcium access channel of the enzyme. The inhibition may involve the binding of CPA with a divalent cation such as Mg2+. The potential for CPA to act as a chelator also has implications for methods to detect this toxin. Certain of the lanthanide metals undergo a dramatic increase in luminescence upon coordination with small molecules that can transfer excitation energy to the metal. This report is the first to describe the coordination of CPA with lanthanide metals, resulting in a substantial enhancement of their luminescence. The luminescence expressed was dependent upon the type of lanthanide, its concentration, and the environment (solvent, water content, pH). Based upon the phenomenon, a competitive assay was also developed wherein terbium (Tb3+) and a series of metal cations competed for binding with CPA. With increasing cation concentration, the luminescence of the CPA/Tb3+ complex was inhibited. The chlorides of ten metals were tested. Inhibition was best with Cu2+, followed by Co2+, Al3+, Fe3+, Mn2+, Au3+, Mg2+, and Ca2+. Two cations in oxidation state one (Na+, K+) did not inhibit the interaction significantly. The interaction of CPA with lanthanides provides a novel recognition assay for this toxin. It also provides a novel way to probe the binding of CPA to metals, giving insights into CPA's mechanism of action.
关键词： mechanism of action,lanthanides,calcium-ATPase,luminescence,mycotoxin,cyclopiazonic acid
更新于2025-09-23 15:22:29
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Chitosan-based hydrogels prepared by UV polymerization for wound dressing
摘要： Chitosan-based hydrogels were prepared by grafting with poly(acrylic acid) (PAA) and poly(hydroxyethyl methacrylate) (pHEMA) through ultraviolet polymerization to further improve its hydrophilic nature and enhance its mechanical properties. The epidermal growth factor (EGF) was incorporated inside the hydrogels to stimulate the wound healing. The physical characterization of chitosan-PAA-pHEMA hydrogel indicates that it is highly hydrophilic with adequate properties for wound dressing purpose. The biological characterization shows that chitosan-based hydrogel retains its thrombogenic and antibacterial properties. The in vivo wound healing experiment demonstrates that the hydrogel-incorporated EGF has better wound healing rate than other dressings.
关键词： hydrogel,Chitosan,2-hydroxyethyl methacrylate,epidermal growth factor,wound dressing,acrylic acid
更新于2025-09-23 15:22:29