四碘荧光素的电化学合成

采用电化学合成法由荧光黄和碘制得赤藓红。用DSA作阳极、不锈钢作阴极,无水Na2CO3溶液作为介质,探索电解时间、荧光黄浓度、无水Na2CO3浓度、电流密度等对产品产率及总色素含量的影响。荧光黄质量浓度为0.010kg/L、碘量为0.016kg/L、电流密度为500A/m2时,产品产率为87.78%,总色素含量可达96.05%。     

荧光素对中国典型香型白酒的荧光鉴别

采用荧光光谱技术与模式识别分析法建立一种快速区分白酒香型的新技术。在495nm可见光激发下分别测定6种香型白酒、荧光素及这两种物质作用后200～800nm之间的荧光光谱．探讨了荧光素与白酒的作用机理。结合模式识别法对310～380nm和504～530nm两个波段对应的荧光强度值进行分层聚类分析（Hierarchieal Cluster Analysis．HCA）和线性判别分析（LinearDiscriminantAnalysis,LDA）,对荧光素区分不同香型白酒的效果进行验证。结果表明,HCA分析能完全区分6种香型白酒,LDA分析对所有样本均得到正确的判别．正确率为100％。因此,这种基于荧光素的荧光光谱法简单、有效,可用于不同香型白酒的快速区分。     

Minimising instilled volume reduces the impact of fluorescein on clinical measurements of tear film stability

Purpose

To compare clinical tear film break-up time measurements obtained non-invasively, with those measured following minimal and conventional volumes of fluorescein instillation.

The use of fluorescein in contact lens aftercare

This short communication reports on the responses of a cohort of more than 2000 contact lens practitioners across five European countries, who were surveyed on the routine use of flourescein in soft contact lens aftercare. Although corneal staining has received extensive interest amongst the academic community, most practitioners do not routinely use fluorescein at aftercare visits. The arguments for not using the agent seem to be somewhat flawed in modern contact lens practice and it is hoped by education and wider communications of the value of staining that more practitioners use it more often.     

Qualitative assessment of tear dynamics with fluorescein profilometry

Purpose

To describe a new methodology for tear-film dynamics assessment by observing fluorescein decay rate over time and to understand the relationship between the newly defined tear fluorescein washout rate (TFWR) and other measures of the tear film behaviour.

Surfactant-induced fluorescence changes in fluorescein dye

Addition of non-ionic surfactants revealed changes in the visible absorbance and fluorescence characteristics of fluorescein dyes. Non-ionic surfactants induced a shift in Δ_max, towards shorter wavelengths along with a decrease in absorbance of the dye. On the other hand, addition of anionic surfactants induced a shift of Δ_max, towards longer wavelengths along with enhancement in absorbance and fluorescence. The absorbance value decreased initially, but increased on further addition of cationic surfactant, whereas fluorescence increased initially but decreased on further addition of cationic surfactant. These changes are attributed to the interaction of surfactant micelle with dye molecules, resulting in change of the coloured quinoid form to the colourless lactone form and vice versa.     

Infusion of fluorescein into corn and waxy rice starches and its controlled release

Food Science and Biotechnology - The effects of concentration, temperature, and time on infusion of fluorescein into corn and waxy rice starches and their controlled release pattern were...     

The effect of rigid lens design on fluorescein fit.

This paper describes an evaluation of rigid lens design undertaken using a computer spreadsheet-based model of fluorescein fit. The study systematically varied rigid lens parameters and corneal topography while monitoring the following key aspects of lens fit. percentage area of apparent corneal alignment, average tear layer thickness and edge clearance. The effect of changes in corneal curvature, corneal asphericity, astigmatism, back optic zone radius, back optic zone diameter and peripheral radii were evaluated. The findings enable a clearer understanding of the relationship between corneal topography, rigid lens parameters and rigid lens fit.     

Fluorescence characteristics of sodium fluorescein–rose bengal ophthalmic solution mixtures

PurposeTo assess fluorescence emission properties of sodium fluorescein–rose bengal mixtures in buffered aqueous solution.MethodsSolutions of sodium fluorescein (NaFl) or rose bengal (RB) or mixtures of these two chemicals were prepared over a range of dilutions in 1% NaCl with 10 mM phosphate buffer to give a pH of 7.5 at room temperature. Absorbance and fluorescence spectra were recorded in 10 mm path length cuvettes.ResultsThe fluorescence emission from NaFl extends between 480 and nearly 600 nm, a spectral range that is also covered by the absorbance of RB (between 500 and 580 nm). With very dilute solutions of NaFl (less than 0.002%), an apparent total quenching of its fluorescence can occur in the presence of 0.01% RB, with a proportionate decrease at lower concentrations of RB.ConclusionsThe presence of RB in an aqueous solution of NaFl at physiological pH appears to act in a similar way to a barrier filter, resulting in the quenching of the measurable fluorescence from NaFl. It remains to be established how substantial or significant such an effect might be if a mixture of NaFl and RB as used as part of the examination of the external eye.     

银纳米粒子基底制备及表面增强拉曼光谱法检测荧光素钠

目的制备具有增强效应的银纳米粒子作为表面增强拉曼光谱的基底,应用于荧光素钠色素的检测,提供一种快速、方便、超灵敏的检测手段。方法用水热法制备银纳米粒子作为表面增强拉曼光谱的基底,通过紫外可见吸收光谱研究以及对比不同激发波长作用下的银纳米粒子增强效应,优化实验条件,对不同浓度的荧光素钠色素进行检测。结果银纳米粒子基底展现出了超灵敏的检测限度和超高的增强效应,在激发波长514 nm、激光强度1 mw、收集时间5 s的实验条件下,荧光素钠色素分子的检测限度达3.01×10~(-4) mg/kg。结论本方法制备的银纳米材料可作为表面增强拉曼光谱的基底,有效应用于荧光素钠色素的检测中,在进口食品安全监测中具有重要的应用价值。     

A new modified fluorescein strip: Its repeatability and usefulness in tear film break-up time analysis

Purpose

To (i) analyze the repeatability of fluorescein instillation from a modified fluorescein strip (MFS) compared to a standard fluorescein strip (FS), and to (ii) observe its usefulness in the measurement of the fluorescein break-up time (FBUT) in comparison to the Tearscope (NIBUT).

Methods

In-vitro: Intra- and inter-observer repeatability in fluorescein instillation from the MFS and FS was evaluated by fluorescence analysis (n = 10, each). In-vivo: BUT of the right eye of 20 randomly selected subjects (mean age 43.3 ± 11.5, range = 21-60 years, 8 males, 12 females) was measured by use of the Tearscope and MFS. Subjects were grouped by the Ocular Surface Disease Index (OSDI) score into 8 OSDI+ and 12 OSDI− by a cut-off value of 15.

Results

In-vitro: Intra-observer 95% limit of agreement (LoA) of the MFS was similar to the FS LoA in observer 1 (O1), but better than the FS LoA in observer (O2) (MFS: O1: LoA = ±1.98 mW; p = 0.179; O2: ±2.71; 0.442; FS: O1: ±1.71; 0.246; O2: ±4.11; 0.512). Inter-observer LoA in fluorescence was better in MFS (±1.42; 0.111) than in FS (±3.71; 0.003). In-vivo: MFS-BUT was significantly shorter than the NIBUT (p = 0.002), but significantly correlated (r = 0.864, p < 0.001). NIBUT and MFS-BUT were significant discriminators (p < 0.001) of OSDI ± (0.948/8 s and 0.938/5 s [AUC/cut-off value]; NIBUT and MFS-BUT, respectively).

Conclusions

The MFS was better in the repeatability of fluorescein instillation than the FS. NIBUT and MFS-BUT were good discriminators of dry eye symptoms, but differ in their cut-off values.     

Mechanisms of superficial micropunctate corneal staining with sodium fluorescein: The contribution of pooling

Purpose

To establish if sodium fluorescein (SFL) dye accumulation within intercellular spaces on the ocular surface contributes to the appearance of superficial punctate corneal staining.

Methods

Thirteen subjects bilaterally wore PureVision™ lenses that had been pre-soaked in ReNu MultiPlus^® multipurpose solution. After 1 h of lens wear, corneal staining with SFL was assessed using a standard slit-lamp technique. Participants who presented with bilateral, corneal staining were selected for further evaluation. A randomly selected eye was rinsed with saline three times. Fellow eyes (control) received no rinsing. After each rinse, the appearance of SFL staining was recorded without any further instillation of the dye. To eliminate any confounding effects of staining due to residual fluorescein in the tear menisci, corneal staining was induced in freshly excised, isolated, rabbit eyes by topical administration of 0.001% PHMB and staining, rinsing and grading were performed as above.

Results

Nine out of 13 subjects presented with bilateral diffuse corneal staining (mean grade ± SD: 2.4 ± 0.7). The mean staining grades in test and control eyes respectively after each of the three rinses were (1) 2.41 ± 0.41, 2.25 ± 0.69 (p = 0.9); (2) 2.34 ± 0.79, 2.1 ± 0.83 (p = 0.8); and (3) 1.71 ± 0.65, 1.60 ± 0.79 (p = 0.6) there was no significant reduction in staining with rinsing (p > 0.05) and no difference was observed between test and control eyes at any sampling-point. Similar observations made in ex vivo rabbit eyes replicated these results.

Conclusions

Pooling or accumulation of SFL solution within intercellular spaces does not appear to contribute to the appearance of superficial micropunctate corneal staining.     

Analysis of the repeatability of tear break-up time measurement techniques on asymptomatic subjects before, during and after contact lens wear.

This study assessed the repeatability of various methods of measuring tear break-up time (TBUT) with and without soft contact lenses (CLs). TBUT was measured on 22 subjects with the tearscope, videokeratoscope and slit-lamp before and after 30 min of soft CL wear, and immediately after CL removal. Slit-lamp corneal TBUT was measured with fluorescein and without fluorescein while wearing CLs. TBUT was measured three times on the right eye only, using each technique in randomised order. TBUT measurements on CLs were repeated a second day. TBUT measurements were highly variable under all conditions and our results indicated a lack of correlation between techniques. The videokeratoscope was the least repeatable; while the tearscope was the most repeatable technique.     

Monitoring of the generation of non-mutagenic benzoic acid compounds during the manufacture of erythrosine

The generation of 2-(2',4'-dihydroxybenzoyl) benzoic acid (DHBBA) and 2-(2',4'-dihydroxy-3',5'-diiodobenzoyl) benzoic acid (DHDIBBA) during the manufacture of erythrosine (Food Red No. 3) was examined. DHBBA is formed as an intermediate during the synthesis of fluorescein, and as fluorescein is produced, it is gradually consumed. However, under inappropriate reaction conditions, it remains in the resulting fluorescein at the termination of synthesis. DHDIBBA is easily obtained by the iodination of DHBBA. These compounds are also found when erythrosine is heated in excessive alkali. The results of the Ames test using DHBBA and DHDIBBA showed they did not possess mutagenic activity. The results clearly demonstrated that establishment of an upper limit for DHBBA and DHDIBBA is important in the quality control of fluorescein and erythrosine.     

Ligation-dependent probe amplification for the simultaneous event-specific detection and relative quantification of DNA from two genetically modified organisms

The application of a ligation-dependent probe amplification (LPA) technique to the simultaneous event-specific detection and relative quantification of DNA from genetically modified organisms in foods is described. The system is based on the ligation of synthetic bipartite probes when hybridized to the corresponding target DNA sequence. The ligation products possess lengths characteristic for each target sequence. Universal primer binding sites (PBS) at the 5′ and 3′-ends enable their subsequent competitive amplification using one common pair of primers. The use of one fluorescein (FAM) labeled primer permits amplification products to be separated and detected via capillary electrophoresis. Respective probes were designed to allow the detection of reference genes in the genomes from maize and soya, as well as of event-specific junction regions in the transgenic maize line MON810 and in Roundup Ready soya. Specificity, sensitivity, and the potential of the technique for the relative quantification of recombinant DNA were assayed using mixtures of DNA extracted from certified reference maize and soybean flours. The novel strategy results in a modular system which can be complemented by further probes to broaden the range of target sequences.     

荧光素钠法测定β-葡聚糖含量研究

该试验通过研究荧光素钠与β-葡聚糖、葡萄糖、乳糖、麦芽糖等结合后荧光最大激发和发射波长发生变化,探索在有多种糖存在溶液中鉴别测定β-葡聚糖含量一种方法。结果显示,荧光素钠与β-葡聚糖混合前后紫外吸收分别为436．5 nm和510．6 mn,荧光素钠与β-葡聚糖结合后荧光最大激发和发射波长发生变化,激发和发射波长分别由487．3 nm,517．6 nm变为475．9 nm和510．6 nm,而与其它糖类,如葡萄糖、乳糖、麦芽糖等结合后荧光性质不发生变化,荧光素钠与β-葡聚糖结合适合比例为6:1(百分含量比)、线性浓度范围在0．1～0．25μg／mL,回归方程为y=-2．014x+1．0757,回归系数为R2=0．9978,用此工作曲线测定青稞粗品中β-葡聚糖粗提物纯度为95％(标准酶法测定结果为96％)。     

Corneal staining: Do we really understand what we are seeing?

Sodium fluorescein (‘fluorescein’) is widely utilised for the evaluation of ocular surface integrity. It is particularly well suited to this task due to its fluorescent properties and its high visibility at low concentrations. Ocular surface fluorescence observed clinically is affected by a number of factors including concentration of fluorescein, thickness of the fluorescein layer, the wavelength of the exciting light source and whether or not a barrier filter is used as part of the viewing system. In this review we have attempted to provide a critical evaluation of the published literature relating to three potential cellular mechanisms involved in corneal surface fluorescence: surface pooling, uptake by cells and ingress around cells. Despite the widespread adoption of use of fluorescein for the assessment of the ocular surface, we contend that the clinical understanding and interpretation of corneal surface fluorescence is based upon assumption, extrapolation and clinical intuition rather than solid evidence-based science underpinning the basic causative mechanisms of this phenomenon. Further research in order to understand the basic interactions between the ocular surface cells and fluorescein should be made a priority in the fields of optometry and ophthalmology.     

Effect of antioxidant oxidation potential in the oxygen radical absorption capacity (ORAC) assay

The “oxygen radical absorption capacity” (ORAC) assay (Ou, B., Hampsch-Woodill, M., Prior, R.L. (2001). Development and validation of an improved oxygen radical absorbance capacity assay using fluorescein as the fluorescent probe. Journal of Agricultural and Food Chemistry 49, 4619–4626) is widely employed to determine antioxidant content of foods and uses fluorescein as a probe for oxidation by peroxyl radicals. Kinetic modeling of the ORAC assay suggests that the lag phase for loss of fluorescence results from equilibrium between antioxidant and fluorescein radicals and the value of the equilibrium constant determines the shape of the lag phase. For an efficient antioxidant this constitutes a “repair” reaction for fluoresceinyl radicals and produces a well defined lag phase. The lag phase becomes less marked with increasing oxidation potential of the antioxidant. Pulse radiolysis confirms that fluoresceinyl radicals are rapidly (k ∼ 10⁹ dm³ mol⁻¹ s⁻¹) reduced by Trolox C, a water soluble vitamin E analogue. ORAC assays of phenols with varying oxidation potentials suggest that it might be employed to obtain an estimate of the redox potential of antioxidants within food materials.     

荧光磁性表面分子印迹聚合物对柚皮苷的荧光偏振检测

采用荧光磁性表面分子印迹法对柚皮苷进行荧光偏振检测。该方法以二氧化硅包裹的磁性颗粒为基质,甲基丙烯酸和丙烯酰胺为单体,并用异硫氰酸荧光素标记,得到同时具有荧光和磁性的表面分子印迹聚合物。并采用荧光偏振法和紫外分光光度法对制备的聚合物结合能力进行检测。通过与比较2种检测方法可知荧光偏振法更为灵敏,检出限为0.1?mg/L。最后对番茄酱中含有的柚皮苷进行回收率检测,回收率达到81.3%以上。说明采用荧光磁性表面分子印迹法对食品中柚皮苷可快速、高效地检测。