ABSTRACT
The application of a liquid/liquid microsegmented flow for serial high-throughput microanalytical systems shows promising prospects for applications in clinical chemistry, pharmaceutical research, process diagnostics, and analytical chemistry. Microscopy and microspectral analytics offer powerful approaches for the analytical readout of droplet based assays. Within the generated segments, individuality and integrity are retained during the complete diagnostic process making the approach favored for analysis of individual microscaled objects like cells and microorganisms embedded in droplets. Here we report on the online application of surface-enhanced micro-Raman spectroscopy for the detection and quantization of analytes in a liquid/liquid segmented microfluidic system. Data acquisition was performed in microsegments down to a volume of 180 nl. With this approach, we overcome the well-known problem of adhesion of colloid/analyte conjugates to the optical windows of detection cuvettes, which causes the so-called "memory effect". The combination of the segmented microfluidic system with the highly sensitive SERS technique reaches in a reproducible quantification of analytes with the SERS technique.
Subject(s)
Microfluidic Analytical Techniques/instrumentation , Microfluidic Analytical Techniques/methods , Spectrum Analysis, Raman/methods , Colloids/chemistry , Gold/chemistry , Molecular Structure , Reproducibility of Results , Sensitivity and Specificity , Surface Properties , Time FactorsABSTRACT
The essential oils of different spices and aroma plants were investigated fast and nondestructively by means of Raman spectroscopy. The main ingredients of these oils, mostly monoterpenes and phenylpropane derivatives, were identified. A hierarchical cluster analysis shows that the oils of the investigated plants cluster chemotaxonomically, which means according to their chemical composition and not according to their botanical degree of relationship. In addition, cross-sections of anise seeds were analyzed applying the Raman mapping technique to localize and investigate the distribution of the oil in situ.
Subject(s)
Oils, Volatile/chemistry , Spectrum Analysis, Raman , Monoterpenes/analysis , Pimpinella/chemistry , Plant Oils/chemistry , Quality Control , Seeds/chemistryABSTRACT
We examined hair from 15 patients with trichothiodystrophy (TTD), a rare inherited disorder with brittle, cystine-deficient hair. They had a wide variety of phenotypes, from brittle hair only to severe intellectual impairment and developmental delay. Polarizing light microscopic examination showed alternating light and dark (tiger tail) bands under polarizing microscopy. Confocal microscopy captured structural features of breaks in intact TTD hairs. The autofluorescent appearance was regular and smooth in normal donors and markedly irregular in sections of TTD hairs possibly reflecting abnormalities in melanin distribution. Scanning electron microscopy revealed numerous surface irregularities. All TTD hair samples had reduced sulfur content. We observed an inverse correlation (R(val)=0.9) between sulfur content and percent of hairs with shaft abnormalities (trichoschisis, trichorrhexis nodosa, or ribbon/twist). There was no association between clinical disease severity and percent of abnormal hairs. Raman spectra of hairs from TTD patients and normal donors revealed a larger contribution of energetically less favored disulfide conformers in TTD hairs. Our data indicate that the brittleness of the TTD hair is dependent upon abnormalities at several levels of organization. These changes make TTD hairs excessively prone to breakage and weathering.
