Dynamic surface enhanced Raman spectroscopy (SERS): extracting SERS from normal Raman scattering.

We have demonstrated two significant benefits of dynamic surface enhanced raman spectroscopy (DSERS) measurements: removal of instrumental and normal Raman interferences in surface enhanced raman spectroscopy (SERS) spectroscopy and site-selective spectroscopy of adsorbate populations on SERS-active particles. Our first example of shelled nanoparticles at very low concentrations confirmed the benefit of DSERS for removal of an overwhelmingly strong solvent spectral interference. The second benefit, site selection, was demonstrated with 4-mercaptopyridine on bare Au nanoparticles to observe a small population of molecules that were spectroscopically unique from the large population of molecules on the particles. The DSERS spectrum originated from excess variance between a small population of adsorbates on the ensemble of nanoparticles.

Lab-on-a-bubble surface enhanced Raman indirect immunoassay for cholera.

We describe a novel sandwich assay based on surface enhanced Raman scattering (SERS) comprised of buoyant silica microspheres coated with antibodies against the ß subunit of the cholera toxin (CT), and gold nanoparticles tagged with a Raman reporter, shelled with silica and coated with antibodies against the ß subunit of the CT. Together these components couple to form a sandwich which, after incubation, floats on the surface of the sample. The buoyant silica microparticle/nanoparticle reporter combination has been coined a lab on a bubble (LoB). LoB materials may provide a platform for rapid detection of antigen in solution and offers advantages over lateral flow or magnetic pull-down assays. The Raman reporter provides a unique and intense signal to indicate a positive analysis. Our limit of detection for the ß subunit of the CT in a buffer based system is 1100 ng.

The value of endoscopic ultrasound after bronchoscopy to diagnose thoracic sarcoidosis.

A clinicoradiological presentation of thoracic sarcoidosis requires histopathology in order to establish the diagnosis. Flexible bronchoscopy has a reasonable diagnostic yield and is the procedure of first choice for diagnosis. Endoscopic ultrasound (endoscopic ultrasound-guided fine needle aspiration/endobronchial ultrasound-guided transbronchial needle aspiration) can help in the diagnosis of sarcoidosis. An implementation strategy of endoscopic ultrasound for the diagnosis of sarcoidosis following negative flexible bronchoscopy results was examined prospectively in 15 clinics. A total of 137 patients (92 males; median age 43 yrs) were included, and sarcoidosis was found in 115 (84%). Alternative diagnoses were tuberculosis, lymphangitis carcinomatosa, pneumoconiosis and alveolitis. All patients were sent for flexible bronchoscopy, which was performed in 121 (88%), resulting in a definite diagnosis in 57 (42%). A total of 80 patients were sent for endoscopic ultrasound, which could be performed in 72 (90%), yielding a definite diagnosis in 47 (59%). Endoscopic ultrasound following negative flexible bronchoscopy avoided a surgical procedure in 47 out of 80 patients. The sensitivity of flexible bronchoscopy for sarcoidosis was 45% (95% confidence interval 35-54%), but 62% (50-72%) if biopsy specimens were taken. The sensitivity of endoscopic ultrasound following negative flexible bronchoscopy results was 71% (58-82%). With this strategy, 97 out of 115 (84% (76-90%)) of proven sarcoidosis was diagnosed using endoscopy. This large prospective implementation study (trial number NCT00888212; ClinicalTrials.gov) shows that endoscopic ultrasound is valuable for diagnosing sarcoidosis after negative flexible bronchoscopy results.

Heme compounds in dinosaur trabecular bone.

Six independent lines of evidence point to the existence of heme-containing compounds and/or hemoglobin breakdown products in extracts of trabecular tissues of the large theropod dinosaur Tyrannosaurus rex. These include signatures from nuclear magnetic resonance and electron spin resonance that indicate the presence of a paramagnetic compound consistent with heme. In addition, UV/visible spectroscopy and high performance liquid chromatography data are consistent with the Soret absorbance characteristic of this molecule. Resonance Raman profiles are also consistent with a modified heme structure. Finally, when dinosaurian tissues were extracted for protein fragments and were used to immunize rats, the resulting antisera reacted positively with purified avian and mammalian hemoglobins. The most parsimonious explanation of this evidence is the presence of blood-derived hemoglobin compounds preserved in the dinosaurian tissues.