Resonance Rayleigh Scattering Research Articles

Determination of glycyrrhizic acid as sweeteners by dual-wavelength overlapping resonance Rayleigh scattering

This study used cationic dyes methyl violet (MV) and neutral red (NR) as probes, based on dual-wavelength overlapping resonance Rayleigh scattering (RRS), and designed two highly sensitive methods for the determination of the natural sweetener glycyrrhizic acid (GZA). In the Clark-Lubs buffer solution, when only MV or NR was present in the solution, they formed supramolecular polymers through hydrogen bonding. When adding GZA at different concentrations, the formation of ionic association complexes led to a subsequent decrease in RRS intensity at two wavelengths in the MV − GZA system and NR − GZA system, and the amount of the decline was proportional to the GZA concentration. The linear ranges were determined as 0.1 − 0.6 mg/L and 0.1 − 0.7 mg/L, with correlation coefficients of 0.9972 and 0.9996, and limits of detection were 0.052 mg/L and 0.016 mg/L, respectively. For this study, reaction conditions were optimized, potential interfering substances were investigated, and the mechanisms behind RRS generation and intensity decrease were discussed. The proposed methods were sensitive, fast, time-saving and efficient, and have been successfully applied to licorice and dried ginger decoction analysis, yielding satisfactory results.

Carbon quantum dots from hemicucur[6]bit and the application for the detection of Pb2+

A macrocyclic compound, hemicucurbit[6]uril (HemiQ[6]), is employed as the carbon source to produce a novel sort of carbon quantum dots (CQDs) with blue fluorescence in aqueous solution. The CQDs are fully identified by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Nuclear Magnetic Resonance (NMR), zeta potential, ultraviolet/visible (UV–vis) and photoluminescence spectroscopy (PL). The nanomaterial is developed for the analysis of Pb2+ in the light of the Resonance Rayleigh scattering (RRS) changes with the increasing Pb2+ concentration. The proposed probe emerges a high selectivity to Pb2+ and excellent sensitivity in the linear concentration range of 0–6 μM with a detection limit low to 0.42 μM, which is superior to the previous values of Pb2+ sensors, as well as the good anti-interference ability is confirmed by the specifical response to Pb2+ in the presence of other metal cations. Therefore, the proposed analysis of Pb2+ is explored for the application in real samples of tap water and lake water, in satisfied results of acceptable recoveries.

Development of Eco-Friendly Scattering and Fluorimetric Methods for the Determination of Clemastine Through Its Interaction with Eosin Y: Assessment of Whiteness, Blueness, and Greenness Tools.

For the first time, clemastine was estimated in this work utilizing two validated resonance Rayleigh scattering (RRS) and fluorimetric methods. The methods relied on forming an association complex in an acidic medium between eosin Y reagent and clemastine. In the spectrofluorimetric approach, the investigated drug was quantified by quenching the fluorescence-emission intensity of eosin Y at 543.5nm. The RRS method relied on enhancing the RRS spectrum at 331.8nm, which is produced when eosin Y interacts with clemastine. Suitable conditions were established for the reaction to achieve maximum sensitivity. The linear values obtained from the spectrofluorimetric approach and the RRS method fall into the ranges of 0.2-1.5µg mL- 1 and 0.25-2.0µg mL- 1, respectively. It was established that the detection limits for these methods were 0.045µg mL- 1 and 0.059µg mL- 1, respectively. The developed methodologies yielded acceptable recoveries when used to estimate the quantity of clemastine in its pharmaceutical tablet dosage form. Regarding the use of greener solvents that were chosen, the suggested and reported methods were compared with the help of the Green Solvents Selecting (GSST) tool for assessing hazardous solvents to achieve sustainability. Furthermore, analytical Eco scale and comprehensive assessments of whiteness, blueness, and greenness were carried out utilizing Modified NEMI, ComplexGAPI, and AGREE evaluation tools. Additionally, recently developed tools such as BAGI and RGB 12 were applied to assess the blueness and the whiteness of the suggested methods.

Study on the interaction between erythrosine B and the cardiac drug amiodarone using fluorescence, scattering, and absorbance spectra and their analytical application.

In an acidic buffered solution, erythrosine B can react with amiodarone to form an association complex, which not only generates great enhancement in resonance Rayleigh scattering (RRS) spectrum of erythrosine B at 346.5 nm but also results in quenching of fluorescence spectra of erythrosine B at λemission= 550.4 nm/λexcitation= 528.5nm. In addition, the formed erythrosine B-amiodarone complex produces a new absorbance peak at 555 nm. The spectral characteristics of the RRS, absorbance, and fluorescence spectra, as well as the optimum analytical conditions, were studied and investigated. As a result, new spectroscopic methods were developed to determine amiodarone by utilizing erythrosine B as a probe. Moreover, the ICH guidelines were used to validate the developed RRS, photometric, and fluorimetric methods. The enhancements in the absorbance and the RRS intensity and the decrease in the fluorescence intensity of the used probe were proportional to the concentration of amiodarone in ranges of 2.5-20.0, 0.2-2.5, and 0.25-1.75 μg/mL, respectively. Furthermore, limit of detection values were 0.52 ng/mL for the spectrophotometric method, 0.051 μg/mL for the RRS method, and 0.075 μg/mL for the fluorimetric method. Moreover, with good recoveries, the developed spectroscopic procedures were applied to analyze amiodarone in its commercial tablets.

Dark‐Field Resonance Rayleigh Scattering Biosensor to Monitor Small Molecules and Determine the Secretory Ability of Single Neuron

AbstractAccurate monitoring of small molecules and precise characterization of the secretory ability of neurons are essential for effective diagnosis of neurological diseases. However, existing technologies for monitoring small molecules only provide approximate results. Plasmonic‐based biosensors are a potential solution in this biological application. Nevertheless, optical sensing nanoparticles require precise control of interparticle distance, particle shape and morphology, which can be challenging. This article discovers that the trapping of small molecules to aptamers induces a conformational change that alters the nanostructure of irregularly shaped Au nanoclusters (NCs) and aptamers due to the strong structure‐property relationships of Au NC‐aptamers. This change can be detected via resonance Rayleigh scattering (RRS) intensity in the dark‐field. This new technology overcomes the challenges of precise control of individual nanoparticles and the difficulty of small spectral peak shifts. The Au NC‐aptamers sensing device has a detection limit of 0.112 pm for dopamine, and this work detects 0.226 pm of dopamine surrounding a single epileptic neuron in polarization, which is more than those of healthy neurons. Overall, this easy‐to‐fabricate Au NC‐aptamers‐based technology has a high potential for monitoring small molecules and determining the secretory ability of single neurons, which is not possible using traditional technologies.

A Dimode Scattering Method for Ultratrace Dinitrofuran Detection with Nanopalladium Molecularly Imprinted Polymer Nanocatalytic Probe.

With four nanoparticles as the nanomatrix, dinotefuran (DNF) as the template molecule, N-isopropylacrylamide as the functional monomer, trimethylolpropane and trimethacrylate as the cross-linker, four nanosurface molecularly imprinted polymer (MIP) bifunctional probes were prepared by microwave synthesis. It was found that palladium nanosurface MIP (Pd@MIP) not only recognized DNF but also had the strongest catalytic effect on the new nanogold indicator reaction of acrylic acid-HAuCl4, which was evaluated quickly with the slope procedure developed by us. The generated gold nanoparticles (AuNPs) not only possessed the resonance Rayleigh scattering (RRS) effect but also strong surface-enhanced Raman scattering (SERS) activity. The combination of Pd@MIP with DNF enhanced the catalytic effect by coupling the nanosurface electrons with π-electrons, thus enhancing both scattering signals. A new Pd@MIP nanoprobe catalytic-SERS/RRS dual-mode analytical platform was developed for the specific and sensitive detection of DNF. The linear ranges of the SERS and RRS methods were 0.075-0.75 and 0.1-0.75 nmol/L, and the limits of detection were 0.03 and 0.06 nmol/L, respectively. The standard deviations were 0.54-2.39%, and the recoveries were 93-105%.

Photocleavable DNA Nanotube-Based Dual-Amplified Resonance Rayleigh Scattering System for MicroRNA Detection Incorporating Molecular Computing-Cascaded Keypad Lock Functionality.

Cascade molecular events in complex systems are of vital importance for enhancing molecular diagnosis and information processing. However, the conversion of a cascaded biosensing system into a multilayer encrypted molecular keypad lock remains a significant challenge in the development of molecular logic devices. In this study, we present a photocleavable DNA nanotube-based dual-amplified resonance Rayleigh scattering (RRS) system for detecting microRNA-126 (miR-126). The cascading dual-amplification biosensing system provides a multilayer-encrypted prototype with the functionality of a molecular computing cascade keypad lock. RRS signals were greatly amplified by using photocleavable DNA nanotubes and enzyme-assisted strand displacement amplification (SDA). In the presence of miR-126, enzyme-assisted SDA produced numerous identical nucleotide fragments as the target, which were then specifically attached to magnetic beads through the DNA nanotube by using a Y-shaped DNA scaffold. Upon ultraviolet irradiation, the DNA nanotube was released into the solution, resulting in an increase in the intensity of the RRS signal. This strategy demonstrated a low limit of detection (0.16 fM) and a wide dynamic range (1 fM to 1 nM) for miR-126. Impressively, the enzyme-assisted SDA offers a molecular computing model for generating the target pool, which serves as the input element for unlocking the system. By cascading the molecular computing process, we successfully constructed a molecular keypad lock with a multilevel authentication technique. The proposed system holds great potential for applications in molecular diagnosis and information security, indicating significant value in integrating molecular circuits for intelligent sensing.

Antibody-labeled gold nanoparticle based resonance Rayleigh scattering detection of S100B.

Traumatic brain injury (TBI) is a sudden brain injury due to an external force that causes a large number of deaths and permanent disabilities every year. S100B has been recognized as a potential objective quantitative biomarker for screening the prognosis of TBI and severe head injury. In this article, an anti-S100B monoclonal antibody was immobilized on cysteamine (Cy) functionalized gold nanoparticles (AuNPs) by EDC-NHS chemistry, which enabled S100B resonance Rayleigh scattering (RRS) detection based on antibody-labeled gold nanoparticles. The prepared conjugates were characterized by ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Based on the specific binding of the antibody and antigen, the RRS intensities at 381 nm and 541 nm wavelengths were significantly enhanced, and thus a dual wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was established. The scattering intensity of the two overlapping peaks was proportional to the concentration of S100B in the range of 0.05-4.5 ng mL-1 with a detection limit of 0.002 ng mL-1. The proposed DWO-RRS method is time-saving, simple, sensitive, and can be used to determine the concentration of S100B in human serum with satisfactory results, which has a promising application in the early diagnosis of TBI.

Rapid and selective RRS determination of ferrocyanide with a nanogold surface molecularly imprinted polymethacrylic acid probe.

In this work, a nanogold surface molecularly imprinted polymer spectral probe (AuNP@MIP) for selectively identifying ferrocyanide was prepared under microwave irradiation using nanogold as the core, ferrocyanide as the template ion, methacrylic acid as the monomer, and ethylene glycol dimethacrylate as the cross-linking agent. AuNP@MIP was found to produce a resonance Rayleigh scattering (RRS) peak at 370 nm. When potassium ferrocyanide (K4Fe(CN)6) was present, a AuNP@MIP-Fe(CN)6 complex was formed, producing RRS-energy transfer (RRS-ET). With an increase in ferrocyanide concentration within a certain range, the RRS intensity at 370 nm decreased linearly, and the detection range was 0.02-0.40 μmol L-1, with a detection limit as low as 0.006 μmol L-1 ferrocyanide. This new method has the advantages of simplicity, rapidity, and selectivity when applied for the determination of K4Fe(CN)6 in table salt.

Integrated resonance Rayleigh scattering approach utilizing Box-Behnken experimental design for the facile quantification of prucalopride in pharmaceutical tablets and human urine with sustainability assessment.

Prucalopride (PCP) is one of the recent drugs used for the regulation of gastrointestinal tract motility and the treatment of constipation. A new, highly sensitive and fast resonance Rayleigh scattering (RRS) approach was suggested for PCP determination. The approach was based on its reaction of PCP with eosin Y in buffered medium (pH 3.5) to form an ion pair association complex which had a significant enhancement in RRS compared to that of eosin Y or PCP alone. The enhancement of RRS intensity had straight correlation to PCP concentration ranging from 150 to 2000 ng mL-1 with 38 ng mL-1 as LOD and 125 ng mL-1 as LOQ. The measurements were done at a wavelength of 365 nm that provided the maximum sensitivity. All the experimental parameters were studied carefully and optimized via Box-Behnken experimental design. The International Council for Harmonization (ICH) guidelines were employed to validate the suggested method and the obtained results proved the appropriate method performance. The method was efficiently utilized to determine PCP in pure form, pharmaceutical tablets and spiked urine samples with no interferences from the surrounding matrices. Furthermore, the greenness of the suggested procedure was confirmed using different green metric approaches.

A new copper nanocluster surface molecular imprinted polymethacrylic acid probe for ultratrace trichlorophenol based on in situ-generated nanogold SPR effects.

A new coinage metal nanocluster surface molecularly imprinted polymethacrylic acid nanoprobe (NC@MIP) for the selective determination of 2,4,6-trichlorophenol (TCP) was prepared via microwave synthesis using 2,4,6-trichlorophenol as a template molecule, copper nanoclusters (CuNC) as a nanosubstrate, and methacrylic acid as a polymer monomer. It was found that the copper nanocluster MIP (CuNC@MIP) shows the strongest catalytic performance for the reduction of HAuCl4 by hydrazine hydrate for the on-site generation of gold nanoparticles (AuNPs) with the surface plasmon resonance (SPR) effects of resonance surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) as well as absorption (Abs). When TCP was added, the CuNC@MIP nanoprobe and TCP-formed CuNC@MIP-TCP nanoenzyme with stronger catalytic activity generated more AuNPs, and the trimodal analytical signal was enhanced linearly. Therefore, a new SERS/RRS/Abs trimodal sensing platform for TCP was constructed, which was simple, rapid, sensitive, and selective. For each mode, the linear ranges were 0.0075-0.075, 0.010-0.10, and 0.010-0.10 nmol L-1, and the detection limits were 0.0010, 0.021, and 0.043 nmol L-1, respectively. The relative deviation of TCP in different water quality was 0.47%-2.5% and the recovery rate was 94.6%-108.6%.

A new and highly efficient CuMOF-based nanoenzyme and its application to the aptamer SERS/FL/RRS/Abs quadruple-mode analysis of ultratrace malachite green.

Malachite green (MG) is highly toxic, persistent, and carcinogenic, and its widespread use is a danger to the ecosystem and a threat to public health and food safety, making it necessary to develop new sensitive multimode molecular spectroscopy methods. In this work, a new copper-based nanomaterial (CuNM) was prepared by a high-temperature roasting using a copper metal-organic framework (CuMOF) as precursor. The as-prepared CuNM was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), and BET surface area analysis. CuNM was found to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce the oxidation product TMBOX; however, subsequently, the MG aptamer (Apt) could be adsorbed on the CuNM surface by intermolecular interaction, which would inhibit the catalytic performance. After the addition of MG to be tested, the CuNM previously adsorbed by the Apt was transformed into its free state, thus restoring its catalytic activity. This new nanocatalytic indicator reaction could be monitored by surface-enhanced Raman scattering (SERS)/resonance Rayleigh scattering (RRS)/fluorescence (FL)/absorption (Abs) quadruple-mode methods. The SERS determination range was 0.004-0.4 nmol L-1 MG, with a limit of detection of 0.0032 nM. In this way, a rapid, stable, and sensitive method for the determination of MG residues in the environment was established.

Nano-level assay of attention-deficit/hyperactivity disorder medicament, atomoxetine by molecular-size-based resonance rayleigh scattering strategy. Employment in content uniformity, dosage form, and plasma analysis

The psychoanaleptic medication atomoxetine (ATX) is prescribed to cure attention-deficit hyperactivity syndrome. ATX works by selective prevention of norepinephrine reuptake. It acts by raising the brain’s natural level of norepinephrine, which is necessary for behavior regulation. In this study, a sensitive and practical experimental method was employed to analyze the presence of ATX. The approach utilized a green chemistry-compatible technique, known as a one-pot experiment. The main principle behind this method was the use of molecular-size-dependant resonance Rayleigh scattering (RRS) phenomenon, which occurred due to the interaction between the dual complex of Cilefa Pink B and ATX. When ATX medication and Cilefa Pink B were combined in an acidic environment, they formed an association complex, leading to an amplification of the RRS signal. This amplification directly correlated with the concentration of ATX, specifically within the range of 40-1250 ng/mL. The RRS signal was monitored at a wavelength of 352 nm. The sensitivity of the method was demonstrated by the determination of the limit of detection (LOD) at 12.9 ng/mL and the limit of quantitation (LOQ) at 39.2 ng/mL. The variables of the method were thoroughly investigated and optimized. To ensure the reliability of the method, it was validated according to the International Council for Harmonisation (ICH) guidelines. Furthermore, the method was successfully applied to analyze ATX in its prescribed dosage form. The achievement of using the established resonance Rayleigh scattering (RRS) technology to analyze the target drug in plasma and ensure content uniformity was a remarkable feat.

A new N/Fe doped carbon dot nanosurface molecularly imprinted polymethacrylate nanoprobe for trace fipronil with SERS/RRS dimode technique

The N and Fe doped carbon dot (CDNFe) was prepared by microwave procedure. Using CDNFe as the nano-substrate, fipronil (FL) as the template molecule and α-methacrylic acid as the functional monomer, the molecular imprinted polymethacrylic acid nanoprobe (CDNFe@MIP) with difunction was synthesized by microwave procedure. The CDNFe@MIP was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier infrared spectroscopy, and other techniques. The results show that the nanoprobe not only distinguish FL but also has a strong catalytic effect on the HAuCl4–Na2C2O4 nanogold indicator reaction. When the nanoprobes specifically recognize FL, their catalytic effect is significantly reduced. Since the AuNPs generated by HAuCl4 reduction have strong surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effects, a SERS/RRS dual-mode sensing platform for detecting 5–500 ng/L FL was constructed. The new analytical method was applied to detect FL in food samples with a relative standard deviation (RSD) of 3.3–8.1 % and a recovery rate of 94.6–104.5 %.

A novel highly active AgMOF-based silver single-atom catalyst and its application to the aptamer SERS/RRS for the determination of aflatoxin B1

A novel highly active silver single-atom catalyst (AgSAC) was prepared by a microwave-assisted solvothermal method using silver covalent organic frameworks (AgMOF) as precursors. It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR), and surface-enhanced Raman scattering (SERS). The experiment found that AgSAC has excellent catalytic performance and can heavily catalyze the nano-reaction of chloroauric acid-malic acid (HAuCl4–H2Mi) to generate gold nanoparticles (AuNPs). The produced AuNPs have strong SERS, resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs) signals. Aflatoxin B1 aptamer (AptAFB1) can be adsorbed to the surface of AgSAC through electrostatic interaction, to reduce the catalytic activity of AgSAC and the SERS/RRS/Abs signal of the system. When the target molecule (AFB1) was added, it will specifically bind to AptAFB1 and release AgSAC, restoring the catalytic activity of AgSAC, thereby restoring the SERS/RRS/Abs signal of the system. Based on this, a simple and sensitive aptamer sensing analysis platform for trace AFB1 was established, and a reasonable catalytic amplification mechanism of AgSAC was proposed. The SERS method exhibited the highest sensitivity, with a linear range of 0.005–0.225 μg/L and a detection limit of 0.002 μg/L.

A new nanosurface molecularly imprinted polymer difunctional probe and on site generated gold nanosol SERS/RRS/Abs trimode determination of trace carbendazim

Although gold nanoparticle (AuNP) surface molecularly imprinted polymers (Au@MIP) were not fresh, this is of interest to spectral analysts due to their possession of high affinity for the target molecules, strong nanocatalysis to amplify the signals, and good stability to obtain accuracy. New avenues of molecular spectroscopy with straightforward, sensitivity and selectivity can be established using Au@MIP nanosol. In this article, a new carbendazim (CAR) Au@MIP nanocatalytic probe was prepared and the new Au@MIP-CAR-HAuCl4-vanillin (VAN) nano indicator reaction was constructed with in situ-generated AuNP as indicator, which with surface-enhanced Raman scattering (SERS), resonance Rayleigh scattering (RRS) and absorption (Abs) effects. Due to space constraints, these imprinted points show high selectivity in the recognition of CAR whose size and shape correspond to the template. The Au@MIP was sensitively detected CAR using SERS/RRS/Abs techniques, with determination range of 0.1–10, 1.5–17.5 and 9.0–30.0 nmol/L, the detection limits of 0.08, 1.0 and 5.0 nmol/L CAR respectively. In addition, the nanocatalytic mechanism was studied.

A novel nanogold sol SERS/RRS dual-mode assay for trace imidacloprid with Ti3C2Tx@Ti-MOFs/peptide bifunctional nanoprobe

The development of rapid, simple, and highly sensitive analytical methods for detecting pesticide residues is crucial for safeguarding the environment and human health. In this study, MXeneTi3C2Tx nanosheets are used to load a titanium-based metal-organic framework (Ti-MOFs) and imidacloprid peptide (PTIMI), and a novel bifunctional nanoprobe (TN@Ti-MOFs/PT) is prepared by irradiation in a domestic microwave oven and stirring at room temperature. Powder X-ray diffraction, transmission electron microscope and Fourier transform infrared spectrometer are used to characterize the prepared nanomaterials. It is found that TN@Ti-MOFs/PT not only specifically recognizes imidacloprid (IMI), but also catalyzes the nanogold indicator reaction to generate gold nanoparticles (AuNP) in an 80 ℃ constant temperature water bath. The generated AuNP can be directly used as an optical probe for resonance Rayleigh scattering (RRS) at wavelength of 370 nm. In the presence of the Victoria blue 4 R molecule probe, it shows a robust surface enhanced Raman scattering (SERS) signal at wavelength number of 1617 cm−1. When the target molecule IMI is added, it can interact with the PTIMI specific base sequence, resulting in PT chain shedding from the TN@Ti-MOFs/PT nanoprobe surface, exposing abundant redox sites and accelerating the redox charge transfer, resulting in AuNP increase and SERS/RRS signal enhancement. As a result, a highly sensitive and specific PT-based dual-mode biosensing platform is developed for the detection of trace IMI, with a linear range of 0.01–0.25 ng/mL and a detection limit of 0.0011 and 0.0039 ng/mL by SERS and RRS assays, respectively. To demonstrate its practical application, the platform is used to detect IMI in vegetable samples, with relative deviations of 1.36–5.86% and recoveries of 95.0–107%. Additionally, the mechanism of nanocatalysis enhancement is also investigated.

A new difunctional liquid crystal nanosurface molecularly imprinted polyitaconic acid nanoprobe for SERS/RRS determination of ultratrace melamine

In this paper, a new dimode scattering spectral method for rapid detection of ultratrace melamine (ML) in dairy products was established by coupling nanosurface molecular imprinting technology with nanocatalytic amplification reaction of liquid crystal particles. It was found that liquid crystal cholesteryl butyrate (CBU) nanosurface imprinted polymers (CBU@MIP) not only recognized ML but also catalyzed the nano indicator reaction of HAuCl4-sodium formate to produce gold nanoparticles with surface-enhanced Raman scattering (SERS) and resonance Rayleigh scattering (RRS) effect. When ML was added, it specifically combined with CBU@MIP to form CBU@MIP-ML conjugates with strong catalytic activity, and SERS and RRS signals increased linearly with the detection limits of 0.0072 pmol/L and 0.093 pmol/L respectively. The method was applied to the determination of ML in dairy products and plastic tablewares with relative standard deviation (RSD) of 2.2–4.4 % and 1.6–4.7 %, and recovery of 95.4 %-108.3 % and 95.9–108.6 % respectively.

Validated spectrofluorimetric and resonance Rayleigh scattering methods for determining naftidrofuryl in varied pharmaceutical samples based on its interaction with erythrosin B.

Naftidrofuryl is a vasodilator medication used for treating cerebral and peripheral vascular diseases. In this study, two spectroscopical techniques, spectrofluorimetric and resonance Rayleigh scattering (RRS), were utilized to quantify naftidrofuryl in its pharmaceutical samples. The developed methodologies in this study rely on a facile process of forming an association complex between erythrosine B reagent and naftidrofuryl under acidic conditions. The fluorimetric assay is based on the ability of naftidrofuryl to quench and decrease the native fluorescence intensity of the reagent when measured at = 550 nm ( = 526 nm). Under similar reaction conditions, the RRS method relies on the observed amplification in the RRS spectrum of the reagent at a wavelength of 577 nm following its interaction with naftidrofuryl. The methods exhibited linearity within the ranges of 0.2 1.6 μg/mL (r2 = 0.999) and 0.1 1.4 μg/mL (r2 = 0.9994), with LOQ values of 0.146 and 0.099 μg/mL, and LOD values of 0.048 and 0.032 μg/mL, for the fluorometric and the RRS methods, respectively. Moreover, the quenching between the dye and naftidrofuryl was studied by Stern-Volmer analysis, and the methodologies were experimentally optimized and validated. Additionally, acceptable recoveries were achieved when the procedures were applied to determine naftidrofuryl in pharmaceutical samples.

Aptamer SERS and RRS determination of trace lead ions using nitrogen-doped carbon dot to catalyze the new nano-gold reaction

Nitrogen-doped carbon dots (CDN) were prepared by microwave hydrothermal method using ammonium citrate (AC) and ethylenediaminetetraacetic acid (EDTA) as precursor. It was characterized by transmission electron microscopy (TEM) and infrared spectroscopy (IR). The CDN was found to catalyze the reduction of HAuCl4 to produce gold nanoparticles (AuNP), among which fructose was an effective reducing agent. Using malachite green (MG) as a molecular probe, the surface enhanced Raman scattering (SERS) intensity at 1617 cm−1 and the resonance Rayleigh scattering (RRS) intensity at 375 nm increased linearly with increasing CDN concentration, respectively. The catalytic activity of CDN is inhibited because the aptamer (Apt) can be adsorbed on the surface of the catalyst CDN. The aptamer (Apt)-Pb2+ reaction and CDN-Apt adsorbing reaction were competitive reaction. When there is Pb2+ that binds more tightly to Apt, Apt is desorbed, and the catalytic ability of CDN is restored. Accordingly, an Apt-mediated nanocatalytic amplification SERS/RRS platform for quantitative detection of lead ions was constructed. For the SERS method, the linear range was 0.5–120 nmol/L with DL of 0.11 nmol/L. For the RRS method, the Pb2+ concentration was linear in the range of 50–400 nmol/L with the RRS intensity, and the DL was 15.32 nmol/L. The analysis platform uses CDN catalyzed nanoreactions to generate AuNP products with SERS activity as a substrate, thus overcoming the shortcomings of Pb2+ without scattering activity, and realizing the possibility of SERS and RRS detection of metal ions. It was used for the determination of Pb2+ in real samples with relative standard deviations were 0.94–2.71 % and recovery was 99.00–103.70 %, respectively. In addition, the mechanism of CDN nanoenzyme heterogeneous catalysis of nano-gold reactions was discussed.