Tuning of optical resonances in asymmetric microtube cavities

We tune optical resonances in rolled-up SiO/SiO(2) microtube cavities by gradually modifying the tube structure through asymmetrical postdeposition of SiO(2). Spectral blueshifts followed by redshifts of the resonant modes are observed in a thin-walled microtube (tube-I), which is attributed to a competition between shape deformation and effective increase of tube wall thickness. In contrast, only a monotonic redshift is detected when asymmetrical deposition is performed on a thick-walled microtube (tube-II). Distinct wavelength-dependent tuning was revealed in both kinds of tubes. Numerical calculations based on perturbation theory are carried out to explain and confirm the experimental results.     

Lab-in-a-tube: on-chip integration of glass optofluidic ring resonators for label-free sensing applications

The fabrication of tubular rolled-up optofluidic ring resonators (RU-OFRRs) based on glass (SiO(2)) material with high quality factors is reported. A novel methodology combining lab-on-a-chip fabrication methods and rolled-up nanotech is presented for the fabrication of fully integrated tubular optofluidic sensors. The microfluidic integration of several RU-OFRRs on one chip is solved by enclosing the microtubes with a patterned robust SU-8 polymeric matrix. A viewport on each microtube enables exact excitation and monitoring of whispering gallery modes with a photoluminescence spectroscopy system under constant ambient conditions, while exchanging the content of the RU-OFRR with liquids of different refractive indices. The refractrometric sensor capabilities are investigated regarding signal stability, sensitivity and reliability. The sensitivity of the integrated RU-OFRR, which is the response of the modes to the change in refractive index of the liquid, is up to 880 nm/refractive index units (RIU).     

Cytotoxic and Antiproliferative Effects of Diarylheptanoids Isolated from Curcuma comosa Rhizomes on Leukaemic Cells

Curcuma comosa belongs to the Zingiberaceae family. In this study, two natural compounds were isolated from C. comosa, and their structures were determined using nuclear magnetic resonance. The isolated compounds were identified as 7-(3,4-dihydroxyphenyl)-5-hydroxy-1-phenyl-(1E)-1-heptene (1) and trans-1,7-diphenyl-5-hydroxy-1-heptene (2). Compound 1 showed the strongest cytotoxicity effect against HL-60 cells, while its antioxidant and anti-inflammatory properties were stronger than those of compound 2. Compound 1 proved to be a potent antioxidant, compared to ascorbic acid. Neither compounds had any effect on red blood cell haemolysis. Furthermore, compound 1 significantly decreased Wilms’ tumour 1 protein expression and cell proliferation in KG-1a cells. Compound 1 decreased the WT1 protein levels in a time- and dose- dependent manner. Compound 1 suppressed cell cycle at the S phase. In conclusion, compound 1 has a promising chemotherapeutic potential against leukaemia.