Direct spectrofluorimetric methods as alternatives to compendial ones used for the quality control of biopharmaceuticals: development, validation and application

Abstract A simple, rapid, precise, accurate and sustainable spectrofluorimetric method (SFM) was developed, validated and applied for the determination of 4-aminobenzoic acid and aromatic amino acids (phenylalanine, tryptophan and tyrosine). These compounds are used in biopharmaceutical formulations and therefore must be analyzed by quality control laboratories to meet the criteria established in pharmacopoeias. In general, potentiometric titration (PT) is described in the compendia as the official analytical technique. However, this method showed low sensitivity and selectivity, and moreover was performed with a non-aqueous solvent (acetic acid), which led to higher consumption of reagents and consequently to the formation of residues. Therefore, the SFM was developed in aqueous medium at pH 7.2 using phosphate buffer. It was successfully validated according to the ICH guidelines and showed good linearity range (r>0.999), specificity, accuracy and precision (within and between days) and robustness. The test results were compared between the SFM and PT using raw material samples, while according to the F- and t-tests at 95% confidence level, no statistical difference was found between the methods

Development status of novel spectral imaging techniques and application to traditional Chinese medicine / 药物分析学报

Traditional Chinese medicine(TCM)is a treasure of the Chinese nation,providing effective solutions to current medical requisites.Various spectral techniques are undergoing continuous development and provide new and reliable means for evaluating the efficacy and quality of TCM.Because spectral tech-niques are noninvasive,convenient,and sensitive,they have been widely applied to in vitro and in vivo TCM evaluation systems.In this paper,previous achievements and current progress in the research on spectral technologies(including fluorescence spectroscopy,photoacoustic imaging,infrared thermal imaging,laser-induced breakdown spectroscopy,hyperspectral imaging,and surface enhanced Raman spectroscopy)are discussed.The advantages and disadvantages of each technology are also presented.Moreover,the future applications of spectral imaging to identify the origins,components,and pesticide residues of TCM in vitro are elucidated.Subsequently,the evaluation of the efficacy of TCM in vivo is presented.Identifying future applications of spectral imaging is anticipated to promote medical research as well as scientific and technological explorations.

Identification of Human Body Fluid Stains and Non-Biological Stains by Three-Dimensional Fluorescence Spectroscopy / 法医学杂志

OBJECTIVES@#To establish a rapid and nondestructive identification method for human body fluid stains and non-biological stains using three-dimensional fluorescence spectroscopy.@*METHODS@#The collected three-dimensional fluorescence spectrum data of human saliva, 3% blood, coffee and Fanta® stains were processed with dimensionality reduction. After wavelet transform, spectral denoising and feature extraction, the classification formula was established. The Fisher discriminant was used for spectrum matching and recognition to establish the analysis method to distinguish stain types.@*RESULTS@#According to the results of data training and comparison, all the recognition accuracies of Fanta®, coffee, saliva and blood were more than 91.39%. Among them, saliva reached 100% recognition accuracy.@*CONCLUSIONS@#Three-dimensional fluorescence spectroscopy is a potential method for rapid and nondestructive identification of biological and non-biological stains.

Oocyte quality assessment in marine invertebrates: a novel approach by fluorescence spectroscopy

BACKGROUND: The assessment of oocyte quality is, nowadays, a major challenge in aquaculture, oocyte cryopreservation, and environmental science. Oocyte quality is a determining factor in fertilization and embryo development; however, there is still a lack of rapid and sensitive cellular markers for its assessment. Currently, its estimation is pre-dominantly based on morphological analysis, which is subjective and does not consistently reflect the developmental competence of the oocytes. Despite several recent studies investigating molecular markers related to oocyte quality, methods currently available for their determination pose various technical challenges and limitations. In this study, we developed a novel approach based on fluorescence spectroscopy to assess different intrinsic physiological parameters that can be employed to evaluate egg quality in marine invertebrates that are widely used as animal models such as sea urchins and mussels. RESULTS: Different physiological parameters, such as viability, mitochondrial activity, intracellular ROS levels, plasma membrane lipid peroxidation, and intracellular pH, for egg quality evaluation have been successfully assessed in sea urchins and mussels by using specific fluorescent dyes and detecting the fluorescent signals in eggs through fluorescence spectroscopy. CONCLUSIONS: Based on our findings, we propose these physiological markers as useful predictors of egg quality in marine invertebrates; they can be estimated rapidly, selectively, and sensitively by employing this novel approach, which, due to the speed of analysis, the low cost, and easy use can be considered a powerful analytical tool for the egg quality assessment.

Diagnostics of non-carious lesions of dental hard tissues with the methods of optical spectroscopy and radiography / Diagnóstico de lesões não cariosas de tecidos duros dentais com os métodos de espectroscopia óptica e radiografia

Objective: This work aims to use new spectroscopic and radiographic methods to study the dental hard tissue erosion and abfraction, as these lesions are actually quite difficult to be diagnosed in clinical practice. Material and Methods: This in vivo study was conducted on 60 patients with early erosion and 60 patients with abfraction at the cervical area by means of laser-induced fluorescence (LIF) and multilayer spiral computed tomography (MSCT). Results: In comparative dental hard tissues studies LIF spectra from intact and affected areas, it was noted multidirectional fluorescence intensity dependence between areas affected by abfraction and intact areas. MSCT technique allowed assessing the degree of damaged areas, especially at deeper stages. Conclusion: Although LIF and MSCT methods presented limitations, it was shown their effectiveness in the diagnosis of abfraction and erosion by detecting changes in the morphological structure as well as in the chemical and mineral composition of affected dental hard tissues. So LIF and MSCT methods can be successfully used in order to develop new medical devices which will provide most accurate clinical diagnose of different stages of dental erosion and abfraction.(AU)

Objetivo: Este trabalho tem como objetivo utilizar novos métodos espectroscópicos e radiográficos para estudar a erosão e a abração do tecido duro dentário, pois essas lesões são realmente bastante difíceis de serem diagnosticadas na prática clínica. Material e Métodos: Este estudo in vivo foi realizado em 120 pacientes com erosão e abração precoces na área cervical por meio de fluorescência induzida por laser (LIF) e tomografia computadorizada em espiral multicamada (MSCT). Resultados: Em estudos comparativos espectros de LIF, de tecidos duros dentais intactos e afetados, observouse dependência da intensidade da fluorescência multidirecional entre as áreas afetadas pela abração e as áreas intactas. A técnica MSCT permitiu avaliar o grau de áreas danificadas, principalmente em estágios mais profundos. Conclusão: Embora os métodos LIF e MSCT tenham apresentado limitações, foi demonstrada sua eficácia no diagnóstico de abração e erosão, detectando alterações na estrutura morfológica e na composição química e mineral dos tecidos duros afetados. Portanto, os métodos LIF e MSCT podem ser utilizados com sucesso, a fim de desenvolver novos dispositivos médicos que fornecerão um diagnóstico clínico mais preciso de diferentes estágios de erosão e abração dentária.(AU)

Analysis of nickel distribution by synchrotron radiation X-ray fluorescence in nickel-induced early- and late-phase allergic contact dermatitis in Hartley guinea pigs / 中华医学杂志(英文版)

Background@#Nickel-induced allergic contact dermatitis (Ni-ACD) is a global health problem. More detailed knowledge on the skin uptake of haptens is required. This study aimed to investigate the penetration process and distribution of nickel in skin tissues with late phase and early phase of Ni-ACD to understand the mechanisms of metal allergy.@*Methods@#Forty Hartley guinea pigs were divided into four groups according to the NiSO4 sensitizing concentration and the NiSO4 challenged concentration: the 5% NiSO4-group, 5% to 10% (sensitization-challenge; late phase group); 10% NiSO4-group, 10% to 10% (sensitization-challenge; early-phase group); and the positive and negative controls. Pathological biopsies were performed on each group. The depth profile of nickel element concentration in the skin of guinea pigs was detected by synchrotron radiation micro X-ray fluorescence spectroscopy (SR-μ-XRF) and micro X-ray absorption near-edge spectroscopy (μ-XANES).@*Results@#In each section, the nickel element concentration in both the 5% NiSO4-group and 10% NiSO4-group was significantly higher than that in the negative control group. In the upper 300-μm section of skin for the early phase group, the nickel element concentration was significantly higher than that in the lower section of skin. In deeper sections (<200 μm) of skin, the concentration of nickel in the early phase group was approximately equal to that in the late phase group. The curve of the late phase group was flat, which means that the nickel element concentration was distributed uniformly by SR-μ-XRF. According to the XANES data for the 10% NiSO4 metal salt solution, structural changes occurred in the skin model sample, indicating that nickel was not present in the Ni2+ aqueous ionic state but in the nickel-binding protein.@*Conclusions@#This study showed that the distribution of the nickel element concentration in ACD skin tissue was different between the early phase and late phase groups. The nickel element was not present in the Ni2+ aqueous ionic state but bound with certain proteins to form a complex in the stratum corneum in ACD model tissue.

Insight into the interaction of inhaled corticosteroids with human serum albumin:A spectroscopic-based study / 药物分析学报

It is well known that the safety and efficacy profile of an inhaled cortocosteroid (ICS) is influenced by the pharmacokinetic properties and associated pharmacodynamic effects of the drug. Freely circulating, protein unbound, and active ICS can cause systemic adverse effects. Therefore, a detailed investigation of drug-protein interaction could be of great interest to understand the pharmacokinetic behaviour of corticosteroids and for the design of new analogues with effective pharmacological properties. In the present work, the interaction between some corticosteroids and human serum albumin (HSA) has been studied by spectroscopic approaches. UV–Vis spectroscopy confirmed that all the investigated corticos-teroids can bind to HSA forming a protein-drug complex. The intrinsic fluorescence of HSA was quenched by all the investigated drugs, which was rationalized in terms of a static quenching mechanism. The thermodynamic parameters determined by the Van't Hoff analysis of the binding constants (negativeΔH andΔS values) clearly indicate thathydrogen bonds and van der Waals forces play a major role in the binding process between albumin and betamethasone, flunisolide and prednisolone, while hydrophobic forces may play a major role in stabilizing albumin-triamcinolone complexes.

Pharmacokinetics of mercury after oral administration of cinnabaris and Fufang Niuhuang Xiaoyan capsule in rats / 中国中药杂志

Fufang Niuhuang Xiaoyan capsule was a classical compound prescription with the efficacy of heat-clearing, detoxification, sedation and anti-inflammation, with cinnabaris as one of its active ingredients. The study focuses on the pharmacokinetics of mercury in rats after oral administration of cinnabaris and Fufang Niuhuang Xiaoyan capsule, in order to explore the effect of combined traditional Chinese medicines on mercury metabolism. In this study, the method of nitric-perchloric acid digestion system coupled with cold atomic-atomic fluorescence spectroscopy (CV-AFS) was adopted to accurately determine mercury in whole blood of rats. Fufang Niuhueng Xiaoyan capsule had three dose schemes of oral administration, namely equivalent clinical dose, 3 times of equivalent clinical dose and 10 times of equivalent clinical dose; And the doses of oral administration of cinnabaris was calculated according to that of Fufang Niuhuang Xiaoyan capsule. SPF grade healthy SD rats were fasted overnight before the oral administration with cinnabaris suspension (or Fufang Niuhuang Xiaoyan capsule suspension). After oral administration of different doses of cinnabaris, no obvious changes in tmax and MRT were observed, while Cmax/dose, AUC0-48 h/dose and AUC0-∞/dose decreased with the increase in dose, indicating that total mercury absorption in body was declining. As the dose increased, Ke, CL/F decreased, and t1/2 increased, indicating that the elimination slowed down, and mercury metabolism showed non-linear dynamic characteristics within a certain range of dose (22-220 mg•kg⁻¹). The total mercury metabolism in the whole blood of rats after oral administration with different doses of Fufang Niuhuang Xiaoyan capsule also showed non-linear dynamic characteristics. The results were correlated with the low solubility of cinnabaris in the body. Compared with cinnabaris, Fufang Niuhuang Xiaoyan capsule showed no obvious changes in V/F and MRT, while Ke, CL/F, tmax decreased, and t1/2, Cmax/dose, AUC0-48 h/dose, AUC0-∞/dose increased significantly. The results showed that Fufang Niuhuang Xiaoyan capsule accelerated absorption, slowed down elimination and improved the total absorption of mercury in the whole blood, indicating that Fufang Niuhuang Xiaoyan capsule may contain components for promoting absorption and alleviating elimination of mercury. Fufang Niuhuang Xiaoyan capsule had an impact on the pharmacokinetics of cinnabaris, and long-term administration of cinnabaris (Fufang Niuhuang Xiaoyan capsule) was possible to cause accumulation of mercury in the body. This study could explain changes in efficacy of Fufang Niuhuang Xiaoyan capsule, evaluate the rationality of compound medicines containing toxic elements and provide scientific basis for the rational and safe use of Fufang Niuhuang Xiaoyan capsule.

Bile salt induced solubilization of methylene blue:Study on methylene blue fluorescence properties and molecular mechanics calculation / 药物分析学报

Methylene blue (MB) is a hydrophobic drug molecule, having importance both as a staining reagent and pharmaceutical agent. MB is strongly fluorescent, with an emission peak at 686 nm (λex 665 nm). In the study, the possibility of MB as an extrinsic fluorophore to study the micellization behavior of bile salts (BSs) was carried out. Since BSs are drug delivery systems, the solubilization of hydrophobic MB drug molecule by BSs was achieved and the nature of association of MB with BS media, namely sodium cholate (NaC) and sodium deoxycholate (NaDC) was evaluated. Change in the photophysical properties of MB is monitored through fluorescence intensity and fluorescence anisotropy at emission peak, 686 nm of MB. Molecular mechanics calculations were carried out to evaluate the MB–BS association. The estimated heat of formation,ΔHf values are–625.19 kcal/mol for MB–NaC and–757.48 kcal/mol for MB–NaDC. The photophysical study also revealed that MB reports the step-wise aggregation pattern of BSs media, as an extrinsic fluorescence probe.

Interaction between Bovine Serum Albumin with Lamivudine,Efavirenz,Tenofovir and Its Mechanism by Fluorescence Spectroscopy and Molecular Docking / 中国药房

OBJECTIVE:To study the interaction between bovine serum albumin(BSA)with lamivudine,efavirenz,tenofovir and its mechanism. METHODS:Fluorescence spectroscopy was used to determine the interaction between BSA with different con-centrations of lamivudine,efavirenz,tenofovir under different temperatures. The fluorescence intensity of them were determined re-spectively;quenching constant(KSV),apparent quenching constant(Kq),binding constant(KA),binding site(n),thermodynamic enthalpy change(ΔH),free energy diversification(ΔG)and entropy change(ΔS)were calculated according to Stern-Volmer equa-tion and so on. Molecular docking model of 3 drugs with BSA was established by using Sybyl 6.7 Flex X model. RESULTS:Kq for the interaction between 3 drugs with BSA were all higher than 2.0×1010 L/(mol·s),and were decreased with the increase of temper-ature;all n were close to 1,and thermodynamic functions ΔG<0,ΔS<0,ΔH<0. Molecular docking model showed that 3 drugs were mainly bound with BSA at Sudlow Ⅰ subdomain site. CONCLUSIONS:There are the interaction between 3 drugs with BSA;fluorescence quenching mainly manifests as static quenching;binding reaction belongs to spontaneous molecular action pro-cess;binding force mainly includes hydrogen bond and Van der Waals'force. The result of fluorescence experiment is consistent with those of molecular docking,and they complement each other.

Interaction between a novel folate receptor targeted rhaponticin conjugate and human serum albumin by molecular spectroscopy / 国际药学研究杂志

Objective To investigate the affinity and interaction of a folate receptor targeted rhapontion(RHA)conjugate (FRHA)with human serum albumins(HSA). Method The interaction between FRHA and HSA under physiological conditions was investigated by fluorescence spectroscopy,UV-visual(vis)spectroscopy and circular dichroism(CD)spectroscopy. Great attempts were made to investigate their interaction mechanism regarding the quenching mechanism,the specific binding site,the type of inter-action force,and the effect of FRHA on the micro-environmental and conformational changes in HSA molecules. Results The forma-tion of the complex of FRHA-HSA would lead to fluorescence quenching. The corresponding values of Ka were 1.4322 × 105,1.1793 × 105,0.9334 × 105 and 0.7896 × 105 L/mol when the temperature were 298,302,306,and 310 K,respectively. The enthalpy change (ΔH)and entropy change(ΔS)were calculated to be-38.772 kJ/mol and-31.39 J/(mol·K),indicating that van der Waals force and hydrogen bonds played major roles in stabilizing the complex. Conclusion The interaction process of the formation of FRHA-HSA is spontaneous. The negative values of enthalpy change(ΔH)and entropy change(ΔS)indicate that van der Waals force and hydrogen bonds play major roles in stabilizing the complex. The conformational investigation reveals theα-helical structure is decreased and the microenvironment of HSA is changed upon the addition of FRHA. The fluorescence quenching of HSA caused by FRHA is static quenching. Furthermore,the results of site marker competitive experiment suggest that FRHA binds to the sub-domainⅡA of HSA.

Interaction between a novel folate receptor targeted rhaponticin conjugate and human serum albumin by molecular spectroscopy / 国际药学研究杂志

Objective To investigate the affinity and inteaction of a folate receptor targeted rhapontion (RHA) conjugate (FRHA) with human serum albumins(HSA). Method The interaction between FRHA and HSA under physiological conditions was investigated by fluorescence spectroscopy, UV- visual (vis) spectroscopy and circular dichroism (CD) spectroscopy. Great attempts were made to investigate their interaction mechanism regarding the quenching mechanism, the specific binding site, the type of interaction force, and the effect of FRHA on the micro-environmental and conformational changes in HSA molecules. Results The formation of the complex of FRHA-HSA would lead to fluorescence quenching. The corresponding values of Ka were 1.4322×105, 1.1793× 105, 0.9334×105 and 0.7896×105 L/mol when the temperature were 298, 302, 306, and 310 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) were calculated to be -38.772 kJ/mol and -31.39 J/(mol·K), indicating that van der Waals force and hydrogen bonds played major roles in stabilizing the complex. Conclusion The interaction process of the formation of FRHA-HSA is spontaneous. The negative values of enthalpy change (ΔH) and entropy change (ΔS) indicate that van der Waals force and hydrogen bonds play major roles in stabilizing the complex. The conformational investigation reveals the α·-helical structure is decreased and the microenvironment of HSA is changed upon the addition of FRHA. The fluorescence quenching of HSA caused by FRHA is static quenching. Furthermore, the results of site marker competitive experiment suggest that FRHA binds to the sub-domain II A of HSA.

Design, synthesis and biological activities of novel 3,6-diamide xanthones / 药学学报

A series of novel xanthones with terminal amine substituents at xanthone's C3 and C6 positions were designed and synthesized as potential ligands for telomeric G-quadruplex DNA. All the compounds in this series were bound to telomeric G-quadruplex in a "thread intercalation" manner that illustrated both in molecular docking and spectrometric studies. Among them, 10c and 10d showed better binding abilities and specific affinity toward G-quadruplex DNA HTG21 over ctDNA in the fluorescence assay. The antiproliferative activities of four screened compounds were examined in three cancer cells by MTT in vitro, and their inhibitory effects were observed at low micromolar ranges. In addition, the PCR stop assay demonstrated that 10c and 10d effectively inhibited the amplification ability of telomerase.

Efeito de adição de rodamina B e fluoresceína sódica a sistemas adesivos não simplificados: aspectos fotofísicos e físico-químicos / Effect of addition of rhodamine B and fluorescein to conventional etch-and-rinse and self-etching adhesive systems: photophysical and physical-chemical aspects

A adição de corantes fluorescentes a adesivos odontológicos possibilita a investigação da distribuição espacial desses materiais na interface dente-restauração, utilizando-se a microscopia confocal de varredura a laser (MCVL). A literatura indica falta de padronização na aplicação de agentes fluorescentes com tal finalidade. Esse estudo sistematizou estratégias para a adição de rodamina B (RB) e fluoresceína sódica (FS) a um sistema adesivo convencional de três passos, Adper Scotchbond Multi-Purpose (MP), e um autocondicionante de dois passos, Clearfil SE Bond (SE), considerados "padrão-ouro" na Odontologia. Os objetivos principais foram (a) determinar a menor faixa de concentrações de RB e FS necessária para produzir imagens satisfatórias da interface dentina-adesivo e (b) avaliar o efeito da adição desses corantes sobre algumas propriedades das resinas. Os adesivos foram marcados com RB ou FS em concentrações decrescentes (0,5, 0,1, 0,02 e 0,004 mg/mL) por meio de um método de dispersão semidireto. O comportamento fotofísico/ fluorescente dos adesivos marcados foi investigado por espectroscopia de fotoluminescência e MCVL. Paralelamente, avaliaram-se os adesivos quanto ao grau de conversão (GC) e ao ângulo de contato (AC). Tanto os resultados de GC como os de AC foram submetidos à análise de variância com dois fatores (adesivo e tratamento) com α = 0,05, seguida de teste post-hoc de Tukey. Os máximos comprimentos de onda de emissão e de excitação da RB e da FS foram influenciados pelo meio polimérico e pela concentração de corante de modo geral. A MCVL preliminar de amostras de adesivo polimerizado, realizada sob condições experimentais padronizadas, mostrou que o comportamento fluorescente da RB em MP e SE foi muito semelhante na mesma concentração de corante, mas o mesmo não pôde ser dito do comportamento da FS, que foi notavelmente inferior no adesivo autocondicionante, SE, na concentração mais alta. Em dentina, os adesivos preparados com RB nas concentrações-alvo de 0,1 e 0,02 mg/mL apresentaram fluorescência ótima; já aqueles preparados com 0,004 mg/mL produziram fraco sinal. Adesivos preparados com FS a 0,5 mg/mL apresentaram ótima fluorescência na interface de adesão, enquanto que concentração menor desse corante não produziu sinal suficiente. Padrões morfológicos aparentemente atípicos foram observados na interface de adesão, quando da associação do adesivo SE com o corante FS. A adição de RB e FS nas quatro concentrações indicadas aos adesivos MP e SE não afetou o GC nem o AC em comparação com os grupos de controle correspondentes. Em suma, a RB mostra-se um corante mais versátil que a FS na avaliação morfológica das interfaces dentina-MP e dentina-SE via MCVL. A menor faixa de concentrações de RB nos adesivos MP e SE, na qual é possível produzir imagens satisfatórias das interfaces, situa-se entre 0,1­0,02 mg/mL. Já o corante FS deve ser adicionado a esses adesivos a pelo menos 0,5 mg/mL para produzir níveis de fluorescência satisfatórios na interface de adesão. A não ocorrência de efeitos deletérios sobre a polimerização e a molhabilidade das resinas estabelece uma margem de segurança para a incorporação desses agentes fluorescentes (em concentração ≤ 0,5 mg/mL) nesses sistemas monoméricos.(AU)

The addition of fluorescent dyes to dental adhesives makes it possible to investigate the spatial distribution of such resin-based materials in the tooth-restoration interface, using confocal laser scanning microscopy (CLSM). Literature indicates a lack of standardization on the application of fluorescent agents for this purpose. This work presents strategies for adding rhodamine B (RB) and fluorescein sodium salt (FS) to a three-step etch-and-rinse adhesive system, Adper Scotchbond Multi-Purpose (MP), and a two-step self-etching one, Clearfil SE Bond (SE), both regarded as "gold standard" in restorative dentistry. The main objectives were (a) to determine the lowest range of RB and FS concentrations required to produce suitable images of the dentin-adhesive interface via CLSM and (b) to investigate potential effects of addition of these dyes on some resin properties. The adhesives were labeled with RB or FS at decreasing concentrations (0.5, 0.1, 0.02 and 0.004 mg/mL) by means of a semi-direct dispersion method. The photophysical/fluorescent behavior of the labeled resins was investigated by photoluminescence spectroscopy and by CLSM. The adhesives were also investigated with regards to the degree of conversion (DC) and contact angle (CA). A two-way ANOVA of "adhesive" and "treatment" was conducted on DC and CA separately, followed by Tukey's test. The maximum emission and excitation wavelengths of RB and FS were influenced by the host polymer and the dye concentration in general. The preliminary CLSM of cured adhesive samples, performed with standardized settings, showed that the fluorescent behavior of RB in MP and SE was very similar in the same dye concentration, unlike the behavior of FS, which was lower in the self-etching adhesive for the highest dye concentration. In dentin, the adhesives prepared with RB at the target concentrations of 0.1 and 0.02 mg/mL presented optimal fluorescence; those with 0.004 mg/mL produced poor signal. Adhesives prepared with FS at 0.5 mg/mL presented optimal fluorescence at the bonding interface, whereas lower concentrations of FS did not produce sufficient signal. Atypical morphological features were observed at the bonding interface, when adhesive SE was used with FS. The addition of RB and FS at the four decreasing concentrations to adhesives MP and SE did not affect DC or CA compared to the corresponding controls. In short, RB is more versatile than FS for the morphological characterization of dentin-MP and dentin-SE interfaces via MCVL. The lowest range of RB concentrations in adhesives MP and SE that can produce suitable images of the bonding interface lies between 0.1­0.02 mg/mL. The dye FS should be added to these adhesives at 0.5 mg/mL at least to produce satisfactory fluorescence levels at the bonding interface. Since negative effects on polymerization and wettability of the resins were not observed, the use of RB and FS (in concentration ≤ 0.5 mg/mL) together with MP and SE should be reliable in terms of resin properties.(AU)

Selection and role of a mix rosemary (Rosmarinus officinalis) - palmitate ascorbyl as antioxidant in a frying process / Selección y función de una mezcla de ascorbil palmitato-romero (Rosmarinus officinalis) como antioxidante en un proceso de fritura

Background: Several investigations report to rosemary as a plant rich in bioactive components with antioxidant potential, in this work, a rosemary extract was obtained that combined with ascorbyl palmitate provides a synergistic protection to a high fat diet (palm olein). Objectives: The objective of this study was to evaluate the effect of the addition of two extracts of rosemary (Rosmarinus officinalis): AP10R and AP30R at three concentrations of 1000, 1500 and 2000 ppm, on the oxidative stability of palm oil subjected to accelerated oxidation conditions and in a frying process. Methods: Lipid peroxidation of palm olein with and without antioxidants was monitored by measuring the concentration of hydroperoxides and total polar compounds; the thermal stability of the phenolic compounds in the oil was evaluated by fluorescence spectroscopy. Results: The AP10R extract at 2000 ppm inhibited olein oxidation by 30% and 60% in terms of total hydroperoxide and polar concentrations, respectively. The AP30 extract at 2000 ppm had similar inhibition behaviors with values of 27% of total hydroperoxides and 54% by total polar compounds in a time from 20 to 25 h. Conclusions: The results indicated that heating reduces the concentration of polyphenols; this decrease was more evident in olein without antioxidants, reflecting the effect of the polyphenols of rosemary extract on the thermal stability of palm olein.

Antecedentes: Diversas investigaciones reportan al romero como una planta rica en componentes bioactivos con potencial antioxidante, en este trabajo, se obtuvo un extracto de romero que combinado con ascorbil palmitato brinda una protección sinérgica a un sistema alimenticio con alto contenido graso (oleína de palma). Objetivos: El objetivo de este estudio fue evaluar el efecto de la adición de dos extractos de romero (Rosmarinus officinalis): AP10R y AP30R a tres concentraciones de 1000, 1500 y 2000 ppm, sobre la estabilidad oxidativa del aceite de palma sometido a condiciones de oxidación acelerada y en un proceso de fritura. Métodos: La peroxidación lipídica de la oleína de palma con y sin antioxidantes fue monitoreada midiendo la concentración de hidroperóxidos y los compuestos polares totales; la estabilidad térmica de los compuestos fenólicos en el aceite se evaluó por espectroscopia de fluorescencia. Resultados: El extracto AP10R a 2000 ppm inhibió la oxidación de oleína en 30% y 60% en términos de la concentración de hidroperóxidos y polares totales, respectivamente. El extracto AP30 a 2000 ppm tuvo comportamientos similares de inhibición con valores de 27% para hidroperóxidos y 54% para el contenido de fenoles totales en un tiempo de 20 a 25 h. Conclusiones: Los resultados indicaron que el calentamiento disminuye la concentración de polifenoles; esta disminución fue más evidente en la oleína sin antioxidantes, reflejando el efecto de los polifenoles del extracto de romero sobre la estabilidad térmica de la oleína de palma.

Effects of urea, metal ions and surfactants on the binding of baicalein with bovine serum albumin$ / 药物分析学报

The interaction of baicalein with bovine serum albumin (BSA) was investigated with the help of spec-troscopic and molecular docking studies. The binding affinity of baicalein towards BSA was estimated to be in order of 105 M?1 from fluorescence quenching studies. NegativeΔH° (?5.6670.14 kJ/mol) and positive (ΔS°) ( t 79.96 7 0.65 J/mol K) indicate the presence of electrostatic interactions along with the hydrophobic forces that result in a positiveΔS°. The hydrophobic association of baicalein with BSA di-minishes in the presence of sodium dodecyl sulfate (SDS) due to probable hydrophobic association of baicalein with SDS, resulting in a negativeΔS° ( ? 40.65 7 0.87 J/mol K). Matrix-assisted laser desorption ionization/time of flight (MALDI–TOF) experiments indicate a 1:1 complexation between baicalein and BSA. The unfolding and refolding phenomena of BSA were investigated in the absence and presence of baicalein using steady-state and fluorescence lifetime measurements. It was observed that the presence of urea ruptured the non-covalent interaction between baicalein and BSA. The presence of metal ions (Ag t , Mg2 t , Ni2 t , Mn2 t , Co2 t and Zn2 t ) increased the binding affinity of ligand towards BSA. The changes in conformational aspects of BSA after ligand binding were also investigated using circular di-chroism (CD) and Fourier transform infrared (FT-IR) spectroscopic techniques. Site selectivity studies following molecular docking analyses indicated the binding of baicalein to site 1 (subdomain IIA) of BSA.&2016 Xi'an Jiaotong University. Production and hosting by Elsevier B.V. This is an open access article.

Advances in biological spectroscopy detection of pathogenic microorganisms / 军事医学

Detection of pathogenic microorganisms has been a hot research field of microbiology.Conventional detection methods,such as isolation and culture, PCR technology, ELISA and genomic sequencing,are all time-consuming and com-plex.Because of the advantages of quick-testing, accuracy, safety and efficiency, spectroscopy has become a new non-inva-sive testing technology and has witnessed rapid development in pathogen detection and disease diagnosis.This article intro-duces three types of common spectroscopy technologies ( laser excitation fluorescence spectroscopy, infrared spectroscopy and Raman spectroscopy) , and also explains how they work in the detection of pathogenic microorganisms.

Determination of As and Hg in eggs by atomic fluorescence spectrometry with microwave digestion and a small amount of acid﹡ / 国际检验医学杂志

Objective To establish a small amount of acid ,microwave digestion‐atomic fluorescence spectrometer method was developed for the determination of arsenic and mercury in eggs at the same time .Methods The sample was digested with 1 ml HNO3 ,After digestion ,the sample was deoxidized with sulfocarbamide and vitamin C and then determined by AFs without dispel‐ling the acid .Results The sample was digested with 1 mL HNO3 ,After digestion ,the sample was deoxidized with sulfocarbamide and vitamin C and then determined by AFs without dispelling the acid .Conclusion The method is simple ,rapid and with little pol‐lution .The determination of arsenic and mercury in eggs by Atomic Fluorescence Spectrometry using microwave digestion were de‐veloped with satisfactory sensitivity ,accurate and precision .

Research of binding reaction mechanism for adenosine in traditional Chinese medicine with serum albumin / 中国药学杂志

OBJECTIVE: To study the binding mechanism between adenosine (Ade), an active component of some traditional Chinese medicines, and human serum albumin (USA). METHODS: The binding constant K and binding sites n were obtained by using fluorescence and UV absorption spectroscopy. In addition, the reaction mechanism was discussed. The energy transfer parameters of the reaction system were determined as was the effect of Ade on HSA's conformation on the basis of Fōrster theory. The binding reaction model of HSA with Ade was constructed through molecular simulation and compared with the experiment results. RESULTS: Ade could bind HSA to form static complex. The binding constant (K) was 1.39 × 10 L3 · mol-1 and binding sites (n) was 0.94. The binding distance r between Ade and HSA was very short, which indicated the phenomenon of energy transfer. Ade changed the hydrophobic environment of the binding domain in HSA and caused certain changes for micro area conformation. Computer molecular docking technology showed that the interactions of Ade with HSA were mainly hydrophobic interaction and hydrogen bonding between purine ring of Ade and amino acid residues of HSA. CONCLUSION: The theoretical calculation and experiment results were in consistency, which provided certain reference for the study of pharmacological mechanism for the active ingredient of some traditional Chinese medicines, adenosine. Copyright 2012 by the Chinese Pharmaceutical Association.

Determination of Tellurium by Atomic Fluorescence Spectrometry Based on Dielectric Barrier Discharge Atomizer / 分析化学

A method has been developed for the determination of tellurium(Te) in soil by hydride generation(HG) atomic fluorescence spectrometry(AFS) based on dielectric barrier discharge(DBD) plasma as low-temperature atomizer. The samples were dissolved by aqua regior acid without matrix separation. The characteristics of the DBD atomizer and the effects of different experimental parameters, such as discharge power, flow rates of discharge gas and AFS carrier gas, lamp current, negative high voltage, observation height, KBH4 concentration and acid medium on the determination were studied and the analytical performances of the present method were evaluated. The detection limit of Te was 0.08 μg/L. The linear range was from 0.5 to 80 μg/L. Recoveries of spiked sample was from 90% to 103 %. The accuracy of this method was verified by the determination of Te in the reference materials. The results agreed well with the reference values.