Capillary action-driven surface-enhanced Raman spectroscopy (SERS) for the identification of phthalocyanine blue in modern paintings based on the BPG spot test.

A method for the extraction and accumulation of Ag nanoparticles utilizing capillary action through a piece of triangular-shaped cotton paper is reported. This method allowed the integration of SERS and the BPG spot test, which are typically employed for examining pigments on paper or in books. Malachite green oxalate was used as the model material for investigating the extent of enhancement when SERS was applied. The dynamic behavior of the Ag nanoparticles was also studied. When the cotton paper was pre-treated with malachite green oxalate, Ag nanoparticles could be extracted and accumulated on the triangular top, resulting in a dramatic SERS improvement. When malachite green oxalate (at a concentration of 10-6 M) was applied using this method, a dramatic analytical enhancement factor of approximately 3000% was obtained. Finally, the method developed in this study was successfully applied to the analysis of pigments in paintings from a university collection. The findings revealed that phthalocyanine blue was a popular pigment used in numerous paintings during the 1950s.

The use of RGB-tracking of color changes during indigo-reduction processes based on LabVIEW machine vision.

The use of an RGB-tracking chart for monitoring the reduction of indigo (color changes) based on the LabVIEW machine vision is demonstrated for the first time. In contrast to a normal analytical chromatographic chart, the time scale is used on the X-axis, but the sum of "RGB-pixels" is used on the Y-axis, instead of "signal intensity". The RGB-tracking chart was obtained from an investigation of the process involved in the reduction of indigo, in which a PC camera was used as a detector and LabVIEW machine vision was simultaneously operated. As a result, when sodium dithionite (Na2S2O4) and yeast were used, respectively, during the indigo-reduction processes, two types of reduction processes were found; the optimized timing for dyeing can be easily determined from the RGB-tracking charts. Furthermore, based on the changes in HSV (hue, saturation, lightness), the use of sodium dithionite provides a higher number of hue and saturation when clothes & fabric were dyed. In contrast to this, a longer time was required for the yeast solution to reach the same high number for hue and saturation. After comparing several series of dyed fabrics, we found that the use of an RGB-tracking chart is indeed a reliable novel tool for measuring color changes that occur during the chemical reactions that are associated with this process.

Selection of aptamers targeting the sialic acid receptor of hemagglutinin by epitope-specific SELEX.

A new SELEX scheme is proposed for the selection of aptamers targeting a specific epitope of a native protein. Anti-sialic acid receptor (SAR) aptamers that inhibit H1 hemagglutination at a low picomole dose are selected accordingly.

Analysis of ephedra-alkaloids using sweeping and cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography methods.

Two stacking methods of capillary electrophoresis (CE) were developed for the separation of very dilute solutions of ephedra-alkaloids, namely ephedrine, pseudoephedrine, methylephedrine, methylpseudoephedrine, norephedrine, and norpseudoephedrine. A sweeping method which uses a carrier comprised of phosphoric acid, sodium dodecyl sulfate (SDS), diethylamine and acetonitrile permits the detection of the alkaloids down to the 10(-1) microg/mL level, and the cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography (CSEI-Sweep-MEKC) method using phosphoric acid, SDS, and acetronitrile as electrolytes can detect down to the 10(-3) microg/mL level. The former requires the conductance of the sample solution to be adjusted beforehand, and only five peaks were observed, two of which were overlapped. The latter is capable of separating the six alkaloids but has a somewhat poorer reproducibility. Using an optimized injection time, it was found that the more diluted a solution is, the greater the sweeping effect will be. The CSEI-Sweep-MEKC method with a 600 s injection time and a 10(-1) microg/mL solution concentration provides an amplification effect of approximately 10(4). The method is suitable for analyses of dilute herb drug extracts and mouse sera. The effect of buffers on the separation and validation of the methods in this study are also discussed.

Sub-diffraction-limit imaging based on the topographic contrast of differential confocal microscopy.

Using the nanometer depth sensitivity of differential confocal microscopy, we detect surface features of lateral dimensions smaller than the diffraction limit without fluorescence labeling. The lateral resolution of the topographic images is further enhanced by a maximum-likelihood estimation algorithm. Based on the comparison of signal and noise at high spatial frequency, we estimate the best lateral resolution of the enhanced images to be 0.15 lambda. In addition, on composite samples this technique can simultaneously display sub-diffraction-limit topographic features and reflectivity heterogeneity.