We have reported a novel optical sensor based on whispering gallery mode (WGM) resonance for measuring thermal deformation in microelectromechanical systems (MEMS) devices. New asymptotic expressions for transverse electric and transverse magnetic waves are developed based on electromagnetic theory derivations for the large size parameter ( times diameter divided by wavelength of light) limits. The optical thermal deformation sensor is characterized both theoretically and experimentally by considering the fact that the size parameter of the microspheres is very large at optical wavelengths. As a prototype thermal deformation sensor, an optical fiber experimental setup with tunable laser diode has been used for realizing the effect of WGM resonances due to change in surrounding temperature of a dielectric microsphere made of BK-7 glass. The quality factor of experimental resonance spectra observed in the laboratory is calculated approximately on the order of 104, which is sensitive enough for detecting micro or nano level deformation changes in the surrounding medium. The novel optical sensor can measure the thermal deformation in the MEMS devices as small as the submicron or nanometer level. This sensor could potentially be used for nanotechnology, MEMS devices, biomedical applications, and other microdevices.
We describe, first to our knowledge, optical resonances of Transverse Electric (TE) and Transverse Magnetic (TM) wave
propagations in dielectric micro-circular-cylinder. New Asymptotic approaches have been developed based on TE and TM
waves. Size parameter (pi times diameter divided by wavelength of the light) is phenomenal to demonstrate Whispering
Gallery Mode (WGM) in dielectric circular cylinder. The developed expressions for size parameter for both TE and TM
waves are very simple and can be used to characterize the resonances in dielectric micro-circular-cylinder. Asymptotic
expressions have been developed based on Electro-Magnetic (EM) wave theory derivations which are mathematically
robust than existing approaches presented in the literatures, and can be used to develop optical sensors by characterizing
resonances in dielectric micro-circular-cylinders. The solutions are shown to be very accurate for large size parameters.
Indocyanine green (ICG) is a near-infrared fluorescence contrast agent, which has enormous potential in early tumor diagnosis and therapy. The objective of this study is to develop biodegradable nanoparticles entrapping ICG and to characterize its intracellular uptake and photodynamic activity in different cancer cell lines. Nanoparticles entrapping ICG were engineered, characterized and the intracellular uptake of ICG was investigated in B16-F10 and C-33A cancer cell lines. The photodynamic activity of ICG-loaded nanoparticles was also investigated. The nanoparticles enhanced the intracellular uptake of ICG and showed significant photodynamic activity, especially at very low ICG concentrations. These preliminary studies indicate the potential of efficient tumor cell delivery and tumoricidal effect of ICG when incorporated in nanoparticles.
Degradation of Indocyanine green (ICG) in aqueous media, limits its application in early tumor diagnosis and therapy. Thus, the objective of this study is to develop biodegradable nanoparticles entrapping ICG and to establish its effectiveness in providing overall stability to ICG. Nanoparticles entrapping ICG were engineered and characterized. The degradation kinetics of ICG in the nanoparticles was investigated in aqueous media. The degradation of ICG in aqueous nanoparticle suspension followed first-order kinetics. Nanoparticles enhanced aqueous, photo and thermal-stability of ICG.
The objective of this study is to engineer a novel nanoparticlulate system for use in early tumor diagnosis. Indocyanine green (ICG)-loaded biodegradable nanoparticles were prepared by using biodegradable polymer, poly(DL-lactic-co-glycolic acid) (PLGA). The ICG entrapment, nanoparticle size, shape, zeta potential the release of ICG from nanoparticles was determined. Also, the effect of ICG entrapment on fluorescence spectra of ICG was measured. The engineered nanoparticles were nearly spherical in shape and efficiently entrapped ICG. The release profile of the nanoparticles was exponential. The entrapment of ICG in nanoparticles caused reduction in its peak fluorescence intensity and shifted its wavelength of peak fluorescence to higher values.
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