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Visualized Quantitation of Trace Nucleic Acids Based on Coffee-Ring Effect on Colloid-Crystal Substrate
摘要： We report a visualized quantitative detection method for nucleic-acid amplification tests based on coffee-ring effect on colloid-crystal substrate. The solution for loop-mediated isothermal amplification (LAMP) of DNA is dropcast on a colloid-crystal surface. After complete drying, a coffee ring containing the LAMP byproduct (i.e. magnesium pyrophosphate) is formed, and it is found that the width of the coffee ring is linearly correlated to the logarithm of the original DNA concentration before the isothermal amplification. Importantly, compared with other substrates, we found that the colloidal-crystal substrate is an appropriate substrate for carrying out the assay of high sensitivity. Based on these findings, we develop a coffee ring-based assay for quantitative readout of trace DNA in sample. The assay requires 0.50 μL sample and is completed in 5 min in a homemade chamber with constant humidity. Semi-quantitative detection of trace DNA is performed using naked eyes. With the use of a smartphone, the DNA in a sample can be quantitatively detected with a limit-of-detection of 20 copies.
关键词： nucleic-acid amplification tests,colloid-crystal substrate,LAMP,quantitative detection,coffee-ring effect
更新于2025-09-10 09:29:36
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Photo-electro-Fenton process applied to the degradation of valsartan: Effect of parameters, identification of degradation routes and mineralization in combination with a biological system
摘要： In this work, the oxidation of the antihypertensive drug valsartan by the Electro-Fenton (EF) and Photo-Electro-Fenton (PEF) processes was studied using a Ti/IrO2 doped with SnO2 as anode, and a carbon felt air diffusion electrode as cathode. Initially, the influence of variables such as supporting electrolyte type, current density, and pH on EF and/or PEF processes was evaluated. The processes were carried out in batch mode, in an open and undivided cell of 200 cm3. The efficiency of the systems was evaluated in terms of the removal of the initial contaminant and rate of mineralization. When NaCl was used as a supporting electrolyte at pH (3.0) and current density 3.46 mA/cm2 adding 3.6x10-5 mol/L of Fe2+, total valsartan (2 ppm) degradation was observed after 45 minutes. After 120 min, even if total removal of valsartan was reached, only 25% of mineralization was obtained. Thus, valsartan degradation tests at near neutral pH in presence of oxalic acid (4.6x10-5 mol/L) lead to comparable results with those obtained at pH 3.0. Primary aromatic intermediates were identified by high resolution mass spectrometry (HRMS) using hybrid quadrupole- time-of-flight (QTOF) MS, from which an initial degradation pathway was proposed. At the end of the PEF system, several aliphatic acids were accumulated and observed, which were effectively removed in a subsequent aerobic biological system. The results demonstrate the feasibility of photo-electro-Fenton and biological coupling process to completely mineralize emerging pharmaceutical pollutants, such as valsartan, at natural pH.
关键词： Emergent Pollutant Degradation,Antihypertensives Elimination,Oxalic Acid,Electrochemical advanced oxidation processes
更新于2025-09-10 09:29:36
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Modification of Phosphoryl Substituents of Phthalocyanines As a Route to Targeted Tuning of Lipophilic-Hydrophilic Properties
摘要： О?,О?-Diethyl-[2-(3,4-dicyanophenoxy)phenyl]phosphonate has been synthesized for the first time and introduced in template condensation on lithium and zinc cations to prepare a series of new neutral and acidic phthalocyanines containing four fragments of 2-oxyphenylphosphonic acid. A scheme of modification of the peripheral substituents at the phosphoryl group was developed allowing a targeted synthesis of phthalocyanine ligands and complexes soluble in organic solvents or aqueous media.
关键词： aggregation in solution,solubility in water,phosphoryl-containing substituents,phthalocyanines,2-oxyphenylphosphonic acid
更新于2025-09-10 09:29:36
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Synthesis of Reduced Graphene Oxide with Adjustable Microstructure Using Regioselective Reduction in the Melt of Boric Acid: Relationship Between Structural Properties and Electrochemical Performance
摘要： The melt of H3BO3 was used to reach a controllable reduced graphene oxide (rGO) synthesis protocol using a graphene oxide (GO) precursor. Thermogravimetric analysis and differential scanning calorimetry (TG/DSC) investigation and scanning electron microscopy (SEM) images have shown that different from GO powder, reduction of GO in the melt of H3BO3 leads to the formation of less disordered structure of basal graphene planes. Threefold coordinated boron atom acts as a scavenger of oxygen atoms during the process of GO reduction. Fourier-transform infrared (FTIR) spectra of synthesized products have shown that the complex of glycerol and H3BO3 acts as a regioselective catalyst in epoxide ring-opening reaction and suppress the formation of ketone C=O functional groups at vacancy sites. Thermal treatment at 800 ?C leads to the increased concentration of point defects in the backbone structure of rGO. Synthesized materials were tested electrochemically. The electrochemical performance of these materials essentially differs depending on the preparation protocol. The highest charge/discharge rate and double-layer capacitance were found for a sample synthesized in the melt of H3BO3 in the presence of glycerol and treated at 800 ?C. The effect of optimal porosity and high electrical conductivity on the electrochemical performance of prepared materials also were studied.
关键词： oxygen scavenger,boric acid,graphene oxide,adjustable microstructure,regioselective catalyst
更新于2025-09-10 09:29:36
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New organic dye/anionic clay hybrid pigments: Preparation, optical properties and structural stability
摘要： Encapsulation and subsequent stabilization of organic dye into layered double hydroxides (LDHs) are investigated. Three commercialized dye molecules such as: acid orange 6, acid yellow 50 and acid green 25, were intercalated in Zn2-Al-LDH by co-precipitation method, analyzed by ICP and UV–Visible, and characterized by XRD at di?erent temperatures. Functionalized organic molecules have been interleaved for the synthesized hybrid LDH materials. It is shown that the e?ect of encapsulation is revealed by the di?erent interactions according to the molecule size and stacking of dye molecules. Thermal behavior of hybrid materials showed a clear enhancement of the structural stability in temperature over the chloride-Zn2Al LDH, indicating that the assembly may appear as a mutual bene?t.
关键词： LDHs,Hybrid materials,Acid yellow 50,Acid orange 6,Acid green 25,Anionic dye
更新于2025-09-09 09:28:46
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Investigating the electrochemical behaviour and detection of uric acid on ITO electrodes modified with differently doped N-graphene films
摘要： Sensitive and selective electrochemical sensors based on indium-doped tin oxide electrodes (ITO) modified with differently nitrogen-doped graphene (NGr) films were successfully developed for the individual and simultaneous determination of uric acid (UA) in the presence of ascorbic acid (AA). The influence of the contents of various N-configurations on the detection of UA on the NGr/ITO based sensors is herein reported for the first time. The contents of various N-configurations on the NGr/ITO electrodes displayed varying promotional effects of the electro-oxidation of UA; attributed to the unique properties of the NGr films arising from the N-configurations. In particular, three N-doped materials prepared with varying amount of graphitic-N, pyrrolic-N, and pyridinic-N allowed the individual detection of UA, in the presence of AA, in the concentration range from 2-320 μM with the detection limits of 0.043 μM to 0.19 μM. Finally, the NGr/ITO-based sensors exhibited successful simultaneous detection of UA and AA, depicting detection limits of 0.051 - 0.19 μM and 0.93 – 5.1 μM within the concentration ranges of 6 - 280 μM and 8 – 800 μM, for the detection of UA and AA, respectively. The study provided insight into an understanding as to how the different contents of N-configurations influenced the electrocatalytic activity of NGr/ITO electrodes for the individual and simultaneous detection of uric acid.
关键词： nitrogen-doped graphene,uric acid,indium-doped tin oxide,ascorbic acid,electrochemical sensors
更新于2025-09-09 09:28:46
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Ultrasensitive Fluorescence Detection of Peroxymonosulfate Based on a Sulfate Radical-Mediated Aromatic Hydroxylation
摘要： Recently, peroxymonosulfate (PMS)-based advanced oxidation processes have exhibited broad application prospects in the field of environment. Accordingly, a simple, rapid and ultrasensitive method is highly desired for the specific recognition and accurate quantification of PMS in various aqueous solutions. In this work, SO4??-induced aromatic hydroxylation was explored, and based on that, for the first time, a novel fluorescence method was developed for the PMS determination using Co2+ as a PMS activator and benzoic acid (BA) as a chemical probe. Through a suite of spectral, chromatographic, and mass spectrometric analyses, SO4?? was proven to be the dominant radical species, and salicylic acid was identified as the fluorescent molecule. As a result, a whole radical chain reaction mechanism for the generation of salicylic acid in the BA/PMS/Co2+ system was proposed. This ?uorescence method possessed a rapid reaction equilibrium (< 1 min), an ultrahigh sensitivity (detection limit = 10 nM; quantification limit = 33 nM), an excellent specificity and a wide detection range (0–100 μM). Moreover, it performed well in the presence of possible interfering substances, including two other peroxides (i.e., peroxydisulfate and hydrogen peroxide), some common ions and organics. The detection results for real water samples further validated the practical utility of the developed fluorescence method. This work provides a new method for the specific recognition and sensitive determination of PMS in complex aqueous solutions.
关键词： benzoic acid,aromatic hydroxylation,fluorescence detection,sulfate radical,salicylic acid,peroxymonosulfate
更新于2025-09-09 09:28:46
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EC-SERS study of phenolic acids sorption behavior on Au, Ag and Cu substrates – effect of applied potential and metal used
摘要： p-coumaric and ferulic acids are natural phenolic phytochemicals present in seeds and leaves usually in very low concentrations. For this reason, their detection and identification using traditional techniques of vibrational spectroscopy is problematic and requires the use of advanced methods to reduce the detection limit. Both p-coumaric and ferulic acids are significant for their antioxidant properties and other biological activities such as antiallergic, hepatoprotective, anticarcinogenic or modulation of enzyme activity. Surface-enhanced Raman scattering (SERS) spectroscopy appears a good tool for their study and detection. In SERS spectroscopy, the mechanism of analytes adsorption on the surface of a plasmonic metal substrate plays a key role, since the formation of a surface complex and its geometry fundamentally influences the enhancement of spectral response. This work was aimed at in-situ SERS spectroelectrochemical study of p-coumaric and ferulic acid showing the dependence on applied potential and changes in adsorption mechanism. The SERS spectra were collected at 785nm excitation wavelength on gold, silver and copper rough electrodes. The applied potential significantly influences the orientation of the molecules towards the active sites of the metal substrate and their overall spatial arrangement on the surface in terms of the individual adsorption mechanisms.
关键词： gold,p-coumaric acid,copper,EC-SERS,silver,ferulic acid
更新于2025-09-09 09:28:46
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Improved production of bacteriorhodopsin from Halobacterium salinarum through direct amino acid supplement in the basal medium
摘要： Enhanced production and growth of Halobacterium salinarum are achieved by direct supplement of essential amino acids in the modified nutrient culture medium. As arginine (R) and aspartate (D) are the main amino acid sources for producing bacteriorhodopsin efficiently from Halobacterium salinarum, both individual and combined effects of these two amino acids (in different compositions) in the basal medium were studied. The BR production is enhanced by 83% on the eighth day (saturated) for all individual and combined amino acid supplements. Maximum production of 201 mg/l is observed for combined amino acid (R3D2)-supplemented culture which is 4.46-fold higher than the conventional culture growth from the basal medium. The obtained results suggest the efficient method to enhance BR production at low cost and thus, open up the possibility to utilize this potential biomolecule for various photonics applications which were earlier restricted due to the high cost of protein molecules.
关键词： Bacteriorhodopsin,Amino acid,Enhanced BR production,Arginine aspartate
更新于2025-09-09 09:28:46
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Effect of the preparation method and metal content on the synthesis of metal modified titanium oxide used for the removal of salicylic acid under UV light
摘要： Titanium dioxide modified with Ag and Fe was synthesized using two preparation methods, characterized and applied to the photocatalytic degradation of salicylic acid in aqueous solution. The modified TiO2 samples were prepared by the sol-gel and wet impregnation methods starting from titanium(IV) isopropoxide and using AgNO3 and Fe(NO3)3·9H2O as precursors of the modifiers, with their content varying between 0 and 5 wt.%. Catalysts characterization was based on powder X-ray diffraction (PXRD), nitrogen physisorption at 77 K, temperature programmed reduction (H2-TPR), chemisorption of NH3 at 343 K and X-ray photoelectron spectroscopy (XPS). The photocatalytic degradation of salicylic acid by modified TiO2 was investigated under ultraviolet irradiation at 298 K considering various concentrations of the catalyst, between 100 and 1000 mgcatalyst/dm3, and of the organic molecule, between 0 and 15 mg/dm3. The catalysts most active in the degradation of salicylic acid were those having the highest Fe content.
关键词： salicylic acid removal,photocatalysis,sol-gel method,Doped titanium oxide,wet impregnation method
更新于2025-09-09 09:28:46