Auxiliary Reagents Research Articles

Solvent-Free Preparation of Tannic Acid Carbon Dots for Selective Detection of Ni2+ in the Environment.

Carbon dots (CDs) are widely used nanomaterials that not only exhibit good biocompatibility and photostability, but also benefit from a simple preparation process and easy functionalization, making them promising for broad applications in the fields of heavy metal ion detection and optoelectronic devices. Based on the excellent optical properties of CDs and the current situation of increasing energy shortages, this paper selects the natural polyphenolic compound tannic acid (TA) found in biomass materials as the carbon source and innovatively adopts a simple and convenient solvent-free pyrolysis method without auxiliary reagents or solvents. The CDs with good water solubility and certain fluorescence properties were directly prepared under the condition of high temperature, and the obtained CDs exhibited blue fluorescence, and a high QY of 35.4% was obtained at 300 °C. The analysis and results demonstrate the selectivity of these CDs for the detection of various metal ion solutions. In particular, these CDs are sensitive to Ni2+ and can be used as fluorescent sensors for the efficient and sustainable detection of Ni2+, whereas previous sensors were often specific to Fe3+ and Hg2+. Thus, a new sensing technique has been developed for the detection of Ni2+ to achieve more sensitive and rapid detection.

Polarimetry-inspired feature fusion spectroscopy (PIFFS) for ammonia sensing in water.

The sustainable use of water resources is inseparable from water pollution detection. The sensing of toxic ammonia nitrogen in water currently requires auxiliary reagents, which may cause secondary pollution. Benefiting from the ability of substances to change light characteristics, this work proposes polarimetry-inspired feature fusion spectroscopy (PIFFS) to detect ammonia. The PIFFS system mainly includes a light source, a quarter-wave plate (QWP), a linear polarizer (LP) and a fiber spectrometer. The target light containing substance information is polarization modulated by adjusting the QWP and LP angles. Then, the Stokes parameters of target light can be calculated by appropriate modulations. The feasibility of PIFFS method to detect ammonia nitrogen is verified by experiments on both standard water samples and environmental water samples. Experimental results show that inspired by the first Stokes parameter, the fused features provide superiority in classifying ammonia concentration. The results also demonstrate the effectiveness of support vector machine-based concentration classification and random forests-based spectral selection. The interaction between light and substances ensures that the proposed PIFFS method has the potential to detect other pollutants.

Diagnostic Value of Dynamic Enhanced Magnetic Resonance Imaging Combined with Serum CA15-3, CYFRA21-1, and TFF1 for Breast Cancer.

Objective To explore the diagnostic value of dynamic enhanced magnetic resonance imaging (MRI) combined with serum CA15-3, CYFRA21-1, and TFF1 for breast cancer. Methods By means of a retrospective study, 60 breast cancer patients treated in our hospital from January 2018 to December 2020 were selected as the breast cancer group, 60 patients with benign breast lesions were selected as the benign group, and 60 healthy individuals who received physical examination in our hospital in the same period were selected as the control group. All study subjects received dynamic enhanced MRI scan and serological tests, their serum CA15-3 and CYFRA21-1 levels were measured with the electrochemiluminescence instrument and original auxiliary reagent, and the TFF1 level was measured with enzyme-linked immunosorbent assay (ELISA). The MRI performance variation in breast lesion patients was analyzed, the serum CA15-3, CYFRA21-1, and TFF1 levels of study subjects were compared among the three groups, and the efficacy of single diagnosis by dynamic enhanced MRI, CA15-3, CYFRA21-1, or TFF1 as well as combined diagnosis was explored by ROC curves. Results Dynamic enhanced MRI showed that malignant lesion had obscure boundary, irregular margin, and heterogeneity after enhancement, and the time-signal intensity curve presented fast-in fast-out; the benign lesion had a clear boundary and smooth margin, 25 cases showed homogeneity after enhancement, and the time-signal intensity curve presented slow-in slow-out; the CA15-3, CYFRA21-1, and TFF1 levels were significantly different among the breast cancer group, benign group, and control group (33.81 ± 12.46 vs 19.02 ± 6.47 vs 9.55 ± 2.64, 4.08 ± 1.41 vs 1.96 ± 1.19 vs 0.99 ± 0.21, 1.39 ± 0.54 vs 1.04 ± 0.26 vs 0.89 ± 0.12, P < 0.05); 57 breast cancer patients were diagnosed by a combined examination, with a sensitivity of 95.0%, specificity of 83.3%, positive predictive value of 74.0%, negative predictive value of 97.1%, accuracy rate of 87.2%, and AUC (95%CI) = 0.892 (0.840–0.943), indicating a significantly higher diagnostic value of the combined examination than the single examination by CA15-3, CYFRA21-1, TFF1, or MRI. Conclusion Combining dynamic enhanced MRI with serum CA15-3, CYFRA21-1, and TFF1 has good efficacy in diagnosing breast cancer, which can be applied in clinical diagnosis of breast cancer.

Icp-Ms Determination of Cl, Br, and I in Botanical and Biological Samples after Digestion with Diluted Hno3 Using O2 or H2o2 as Auxiliary Reagents

Icp-Ms Determination of Cl, Br, and I in Botanical and Biological Samples after Digestion with Diluted Hno3 Using O2 or H2o2 as Auxiliary Reagents

MoS2 nanosheets for the detoxification of Hg2+ in living cells

MoS2 nanosheets were exfoliated using sodium phytate as an auxiliary reagent and applied for the detoxification of Hg2+ in living HepG2 cells.

Chromatographic Determination of Total Selenium in Biofortified Alliumsp. following Piazselenol Formation and Micro-Solid-Phase Extraction.

Herein, a method based on selective piazselenol formation is applied for total selenium determination in biofortified Allium species. Piazselenol is formed by reacting Se(IV) with an aromatic diamine, namely 4-nitro-1,2-phenylenediamine, in acidic medium. Samples were digested in a nitric acid/hydrogen peroxide open system, followed by selenate reduction in hydrochloric acid. Reaction conditions were optimized in terms of pH, temperature, reaction time, and other auxiliary reagents for interference removal, namely, EDTA and hydroxylamine. For the extraction of the selectively formed 4-nitro-piazselenol, micro-solid-phase extraction (μSPE) was applied, and the analysis and detection of the corresponding complex was performed by HPLC coupled with DAD. An external standard calibration curve was developed (R2 = 0.9994) with good sensitivity, and was used to calculate the total selenium content from several Allium plants material, with good intermediate precision (RSD% < 16%). The accuracy of the method was evaluated using both, a comparison with an accepted reference method from our previously published data, as well as three certified reference material with recoveries between 84–126%. The limit of detection was determined to be 0.35 μg/g (in solids) and 1.1 μg/L (in solution), while the limit of quantification was 1.07 μg/g and 3.4 μg/L (in solution). Using the proposed method, selenium content can be quickly and accurately determined in several types of samples. In addition, this study present experimental conditions for overcoming the interferences that might be encountered in selenium determination using piazselenol.

Preparation of @ZIF-8 Immobilized Enzyme by Using Cysteine as Auxiliary Reagent and Its Characterization

Preparation of @ZIF-8 Immobilized Enzyme by Using Cysteine as Auxiliary Reagent and Its Characterization

Healable and Rearrangeable Networks of Liquid Crystal Elastomers Enabled by Diselenide Bonds.

Based on liquid crystal elastomer (LCE) materials, hierarchically structured soft actuators can meet some requirements for "human-friendly" working mode and execute complex tasks with intelligent adaptation to environmental changes. However, few researchers have paid much attention to the preparation methods of multicomponent/hierarchical LCE actuators. In this communication, we demonstrate the successful integration of an exchangeable diselenide chain extender for the preparation of dynamic LCEs, which could be reprogrammed on heating or under visible light illumination. Moreover, the rearrangeable polydiselenide networks could be applied to develop the self-welding technology toward fabricating hierarchically structured LCE actuators with sophisticated deformability without using any auxiliary reagent (adhesive, tape, catalysts or initiator) during the assembling process.

Healable and Rearrangeable Networks of Liquid Crystal Elastomers Enabled by Diselenide Bonds

AbstractBased on liquid crystal elastomer (LCE) materials, hierarchically structured soft actuators can meet some requirements for “human‐friendly” working mode and execute complex tasks with intelligent adaptation to environmental changes. However, few researchers have paid much attention to the preparation methods of multicomponent/hierarchical LCE actuators. In this communication, we demonstrate the successful integration of an exchangeable diselenide chain extender for the preparation of dynamic LCEs, which could be reprogrammed on heating or under visible light illumination. Moreover, the rearrangeable polydiselenide networks could be applied to develop the self‐welding technology toward fabricating hierarchically structured LCE actuators with sophisticated deformability without using any auxiliary reagent (adhesive, tape, catalysts or initiator) during the assembling process.

Lateral flow immunoassay based on gold magnetic nanoparticles for the protein quantitative detection: Prostate-specific antigen

Point-of-care testing (POCT) demands for rapidly obtaining test results by means of portable analytical instruments and auxiliary reagents at the sampling site. It's important for tumor marker to be recognized and detected in early clinical diagnosis. Many studies focused on producing small portable devices that would allow fast, accurate, and on-site detection. This study aimed to report a magnetic quantitative lateral flow immunoassay (LFIA) system based on poly (acrylic acid) (PAA)-modified gold magnetic nanoparticles (PGMNs) for detecting prostate-specific antigen (PSA) qualitatively and quantitatively. The result was easily achievable with a portable magnetic reader within 15 min. Under optimal conditions, as low as 0.17 ng/mL PSA could be detected. The method was validated using a well-established Solin electrochemiluminescence immunoassay and showed high consistency in detecting 84 serum samples (R2 = 0.98). The quantitative LFIA based on PGMNs established in this study was proven to be rapid, accurate, sensitive, and inexpensive. As a POCT, it can be potentially developed for the quantitative diagnosis of other disease-related protein biomarkers.

A photoelectrochemical immunosensor based on ReS2 nanosheets for determination of collagen III related to abdominal aortic aneurysm

3-Butyl-1-dodecyl-imidazolium bromide ionic liquid was successfully synthesized and used as an auxiliary reagent for the exfoliation of ReS2 bulk crystal to produce ReS2 nanosheets. The photocurrent response of ReS2 nanosheets was enhanced 1.5-fold as integration with ionic liquid. ReS2 nanosheets were employed as a photosensitive element to construct a photoelectrochemical platform for immobilizing collagen III antibodies. As a result, a photoelectrochemical immunosensor was fabricated for determining collagen III. The ionic liquid can accelerate the separation of electron-hole pairs generated from ReS2 nanosheets, and thus help to improve photoelectrochemical sensing characteristics. Some experimental conditions were optimized to provide satisfied signals for determining collagen III. Under optimized conditions, the photocurrent decline of the PEC immunosensor is linearly related to the logarithm of collagen III concentration in the range from 0.001 to 1000 ng mL−1 with a detection limit of 0.1 pg mL−1. The ReS2 based photoelectrochemical immunosensor has also been successfully used for assaying collagen III in clinical serum samples.

Utilization of N-bromosuccinimide for the sensitive spectrophotometric determination of pipazethate HCl as antitussive drug in pure and dosage forms

Three simple, sensitive, precise, reproducible and validated spectrophotometric methods have been developed for the quantification of pipazethate HCl as antitussive drug in pure and dosage forms. The methods are based on utilization of N-bromosuccinimide as an oxidant and three dyes, amaranth, methylene blue, and indigo carmine, as auxiliary reagents. The proposed methods are based on oxidation reaction of pipazethate HCl with a known excess of N-bromosuccinimide in acid medium, followed by determination of unreacted N-bromosuccinimide by the reaction with a fixed amount of dyes, amaranth, methylene blue, and indigo carmine followed by the measurement of the absorbance at 520, 663 and 610nm, respectively. The optimization of the reaction conditions was investigated. Under the optimum conditions, linear relationships with good correlation coefficients (0.9998-0.9999) were found over the concentration ranges of 0.3-9.0, 0.5-12 and 0.5-10μgmL-1 with a limit of detection (LOD) of 0.1, 0.15 and 0.15μgmL-1 using amaranth, methylene blue, and indigo carmine methods, respectively. Intra-day and inter-day accuracy and precision of the methods have been evaluated. No interference was observed from the common tablet excipients. The developed methods were validated in accordance with ICH guidelines and successfully applied to the analysis of pipazethate HCl in dosage forms with good accuracy and precision. The reliability of the methods was further ascertained by performing recovery studies via the standard addition method. Statistical comparison of the results obtained by applying the proposed methods with those of the reported method by applying Student's t-test and variance ratio F-test at the 95% confidence level revealed good agreement and indicates no significant difference in accuracy and precision.

Application of innovative technology of biolayer interferometry in basic research in the development of new vaccines

One of the effective methods for real-time protein analysis is based on the phenomenon of light interference and is called "biolayer interferometry". The patented Bio-Layer Interferometry (BLI) technology, which underlies ForteBio Octet platform, provides surface interaction analysis for disposable fiber optic biosensors. The article presents the technology of interferometry of the biolayer of BLI molecules, which can be used to determine the kinetics and affinity, for the specific quantitative determination of molecules bound to the biosensor. The purpose of the review was to summarize scientific data on the use of the interferometry technology of the biolayer of BLI molecules in determining the concentration of proteins and studying the kinetics of interaction using Octet systems when creating new vaccines in many ways. BLI biolayer interferometry technology allows protein concentration measurements to be performed without using of labels or auxiliary reagents, even in untreated media. It is characterized by a sensitivity up to several ng/cm3, provides accurate quantitative changes in a few seconds, and not in many hours like traditional methods (ELISA, HPL Coder). The affinity, concentration, and binding kinetics of the studied proteins can be measured in 4- ml drop samples directly on the laboratory table. The technology of interferometry of the biolayer of BLI molecules can be used by researchers to select the most immunogenic epitopes in the molecular structure of a pathogen, it is also possible to conduct studies on the characterization and recognition, diversity and distribution of pathogens, affinity for antibodies, it is possible to characterize the immune response of the host, to study molecular interactions between the pathogen and the host, and to carry out therapeutic and clinical research. Currently, the technology of interferometry of the biolayer of BLI molecules has already been used in fundamental studies of pathogens that cause HIV, herpes, Ebola, influenza A H7N9, Dengue, malaria, Zika virus, diphtheria, tuberculosis, listeriosis, gastroenteritis, respiratory pathology, including the COVID outbreak. -19.

Development of an eco-friendly sample preparation protocol for metal determination in food samples: an oxygen pressurized single reaction chamber using diluted nitric acid.

Many efforts have been recently made to improve the digestion efficiency by using powerful equipment or by using an auxiliary reagent. In this work, an alternative method is reported, which explores a digestion system based on a single reaction chamber (SRC) technology pressurized with O2 for reducing the amount of acid, without impairing the digestion efficiency. Before digestion, the system was pressurized with compressed air (20 bar, 20% O2) while the temperature was evaluated from 180 up to 270 °C. The procedure was also carried out under O2 pressure (20 bar). For each temperature several acid concentrations were evaluated (0.1 to 3 mol L-1 HNO3), being possible to correlate the effectiveness of each acid concentration with temperature. The proposed method was applied to the simultaneous digestion of several organic matrices with variable content of fat, protein, and carbohydrate (whole milk powder, bovine liver, parsley, and linseed). The residual carbon content was lower than 4% (C lower than 200 mg L-1 in digests), showing the high digestion efficiency of the proposed approach. Up to 250 mg of all food matrices were digested using a sub-stoichiometric amount of HNO3 (1 mol L-1 solution), which was only achieved due to the use of O2 as an auxiliary reagent. Barium, Ca, Cu, Fe, K, Mg, Mn, Na, Sr, and Zn were determined by ICP-OES, and the accuracy was better than 95% for standard reference materials of corn bran, whole milk powder, and bovine liver. It is an important feature, being in agreement with green chemistry recommendations because very low amounts of reagents are required for sample digestion, as well as low amounts of residues are generated.

Waste free Technologies for Production of Nanocrystalline Cellulose and its Composites

In this paper, waste-free technologies are proposed for the production of nanocrystalline cellulose (NCC), its semi-finished products and composites. The following optimal conditions for the cellulose hydrolysis stage were found: concentration of sulfuric acid 40 wt.%, temperature 80oC, duration 1 h, acid to cellulose ratio 7. After hydrolysis stage, the depolymerized cellulose was separated from the acid, washed, diluted with water and disintegrated to release individual nanocrystalline particles. Finally, the diluted dispersion of NCC was evaporated to obtain a commercial product such as concentrated NCC paste. For the production of composites, the acid in unwashed hydrolyzed cellulose was neutralized and precipitated with calcium base (e.g. calcium hydroxide) in order to obtain a white pigment, calcium sulfate (CS). Moreover, the spent sulfuric acid and acidic wastewater were collected and treated with a special auxiliary reagent to reuse and convert the acid into a valuable by-product, selling of which significantly reduces the cost of NCC. The wastewater collected after washing, neutralization and evaporation was purified and returned back to the technological cycle. To reduce the production cost, expensive stages - disintegration and evaporation of diluted dispersion, should be eliminated; as a result, cheap semi-finished products containing aggregates of NCC or its composite with inorganic particles of CS were manufactured along with by-product.

Advances in Electrochemical Aptasensors Based on Carbon Nanomaterials

Carbon nanomaterials offer unique opportunities for the assembling of electrochemical aptasensors due to their high electroconductivity, redox activity, compatibility with biochemical receptors and broad possibilities of functionalization and combination with other auxiliary reagents. In this review, the progress in the development of electrochemical aptasensors based on carbon nanomaterials in 2016–2020 is considered with particular emphasis on the role of carbon materials in aptamer immobilization and signal generation. The synthesis and properties of carbon nanotubes, graphene materials, carbon nitride, carbon black particles and fullerene are described and their implementation in the electrochemical biosensors are summarized. Examples of electrochemical aptasensors are classified in accordance with the content of the surface layer and signal measurement mode. In conclusion, the drawbacks and future prospects of carbon nanomaterials’ application in electrochemical aptasensors are briefly discussed.

Influences of four kinds of calcium salts on the functional performances of gelatin composite films

Fish gelatin films were prepared with gelatin as the main raw material and four kinds of salts, including CaCl2, CaSO4, hydroxyapatite and Ca3(PO4)2, as the auxiliary reagents. The types of the anions and the concentrations of the calcium salts could affect the light transmission, swelling ratio, tensile strength, and elongation at break of gelatin films. The relationship between them was studied in this paper. The experimental data were analyzed and it is noted that the swelling ratio of the gelatin film was improved after adding the calcium salts. The swelling ratio of the hydroxyapatite/gelatin composite film was significantly bigger than that of other composite films. There is no significant effect on the light transmittance of the gelatin film after adding the calcium salts. The improved mechanical performances were found in the composite gelatin films by adding calcium chloride, calcium sulfate, and calcium phosphate. In comparison, calcium phosphate performed the greatest influence on improving the mechanical performances of the composite films.

Dispersive Liquid-Liquid Microextraction Based on Ionic Liquid and Spectrophotometric Determination of Bilirubin in Biological Samples

Background: An Ionic Liquid-based based Dispersive Liquid-Liquid Microextraction (IL-DLLME) method was not applied to preconcentration and determination of bilirubin. Ionic Liquids (ILs) are new chemical compounds. In recent years, Ionic Liquids (ILs) have been employed as alternative solvents to toxic organic solvents. Due to these perfect properties, ILs have already been applied in many analytical extraction processes, presenting high extraction yield and selectivity for analytes. Methods: In this study, IL-DLLME was applied to biological samples (urine and serum) for the spectrophotometric detection of bilirubin. For bilirubin analysis, the full-color development was based on the reaction with periodate in the presence of hydrochloric acid. The high affinity of bilirubin for the ionic liquid phase gave extraction percentages above 98% in 0.3 M HCl solution. Results: Several IL-extraction parameters were optimized and room temperature ionic liquid 1-butyl- 1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and ethanol were used as extraction and disperser solution. The linear range was found in the range of 0.5-6.0 μM (0.3-3.5 μg mL-1) and the limits of detection of the proposed method was 0.5 μM (0.3 μg mL-1). The proposed method was applied for the preconcentration and separation of trace bilirubin in real urine samples. Also, the recoveries for bilirubin in spiked biological samples (urine and serum) were found to be acceptable, between 95-102%. Conclusion: The proposed IL-DLLMEapproach was employed for the enrichment and determination of trace levels of bilirubin in urine samples using NaIO4 as an oxidizing agent and Uv-vis spectrophotometric detection. The periodate oxidation of bilirubin is rapid, effective, selective, and simple to perform. The method contains only HCl, NaOI4, and an anionic surfactant. The method may be useful for economizing in the consumption of reagents in bilirubin determining. The IL-DLLMEmethod ensures a high yield and has a low toxicity no skin sensitization, no mutagenicity and no ecotoxicity in an aquatic environment since only very low quantities of an IL is required. For full-color formation, no any extra auxiliary reagents are required. Besides, the IL-DLLME technique uses a low-cost instrument such as Uv-vis which is present in most of the medical laboratories.

Near-IR aza-BODIPY-based probe for the selective simultaneous detection of Cu2+ in aqueous buffer solutions and its application in biological samples

On the basis of an aza-BODIPY core, a near-IR BDT probe was designed for Cu2+ detection. The Cu2+ sensing ability of the BDT probe demonstrated absorbance and fluorescence signals in near-IR regions. The probe capably detected Cu2+ with high sensitivity and selectivity in aqueous buffer solutions with a low detection limit of 3.75 ppb which is lower than the acceptable drinking water concentration specified by the U.S. Environmental Protection Agency and World Health Organization. The sensing ability of the probe also increased selectivity to Cu2+ over Hg2+ by adding cysteine as an auxiliary reagent. The binding of BDT-Cu2+ was proven to be 2:1 via molecular modeling and Job’s plot analysis. Interestingly, the BDT probe exhibited outstanding chromogenic and luminescent change in the presence of only Cu2+ and could detect Cu2+ in HepG2 cells as a biological sample.

VALIDATED SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF MONTELUKAST SODIUM IN PURE AND DOSAGE FORMS USING N-BROMOSUCCINIMIDE AND DYES

Objective: Simple, sensitive, precise, reproducible and validated spectrophotometric methods have been developed for the quantification of montelukast sodium as leukotriene receptor antagonist drug, in pure and dosage forms (tablets).&#x0D; Methods: The methods use N-bromosuccinimide (NBS) as an oxidant and three dyes, amaranth, methylene blue, and indigo carmine, as auxiliary reagents. The three methods are based on oxidation reaction of montelukast sodium with a known excess of N-bromosuccinimide (NBS) in acid medium, followed by determination of unreacted NBS by the reaction with a fixed amount of dyes, amaranth, methylene blue, and indigo carmine followed by the measurement of the absorbance at 520, 664 and 610 nm, respectively.&#x0D; Results: Under the optimum conditions, linear relationships with good correlation coefficients (0.9993-0.9996) were found over the concentration ranges of 0.5-10, 1.0-12 and 0.5-8.0 µg/ml with a limit of detection (LOD) of 0.15, 0.3 and 0.14 µg/ml using amaranth, methylene blue, and indigo carmine methods, respectively. Intra-day and inter-day accuracy and precision of the methods have been evaluated. No interference was observed from the common tablet excipients.&#x0D; Conclusion: The proposed methods were validated in accordance with ICH guidelines and successfully applied to the analysis of montelukast sodium in dosage forms (tablets). The reliability of the methods was further ascertained by performing recovery studies using the standard addition method. Statistical comparison of the results obtained by applying the proposed methods with those of the reported method by applying student’s t-test and F-test revealed good agreement.