measurement-particle-size-distribution-turbid-solutions-dynamic-light

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a ...

University of Tokyo

The effects of dietary antioxidative and chemopreventive rosemary phytochemicals on the function of the human drug efflux transporter P-glycoprotein (MDR1, ABCB1) and multidrug resistance protein 1 (MRP1, ABCC1) were investigated using P-glycoprotein-overexpressing human carcinoma KB-C2 cells and human MRP1 gene-transfected KB/MRP cells. The effects of natural phytochemicals found in rosemary such as carnosic acid, carnosol, rosmarinic acid, and ursolic acid were investigated. The accumulation of daunorubicin or rhodamine 123, fluorescent substrates of P-glycoprotein, in KB-C2 cells increased in the presence of carnosic acid, carnosol, and ursolic acid in a concentration-dependent manner. In contrast, carnosic acid, carnosol, rosmarinic acid, and ursolic acid had no effects on the accumulation of calcein, a fluorescent substrate of MRP1, in KB/MRP cells. The ATPase activities of P-glycoprotein were stimulated by carnosic acid, carnosol, and ursolic acid. KB-C2 cells were sensitized to vinblastine cytotoxicity by carnosic acid, showing that carnosic acid reverses multidrug resistance. These results suggest that rosemary phytochemicals, such as carnosic acid, have inhibitory effects on anticancer drug efflux transporter P-glycoprotein and may become useful to enhance the efficacy of cancer chemotherapy.

Inhibition of anticancer drug efflux transporter P-glycoprotein by rosemary phytochemicals.

We developed a new technique that conducts dynamic light scattering (DLS) under a microscope with high spatial resolution. This technique dramatically extends the range of DLS application from transparent to opaque samples. The total scattered electric field contains both electric field generated from the samples and time-independent reflected electric field. These two components are decomposed by applying a partial heterodyne method. By using this technique, we successfully calculate the characteristic size distribution of both multiple-scattering samples and strong light-absorbing samples. This is the first study to observe the collective motion of particles in a highly concentrated solution by using DLS.

Dynamic light scattering microscope: accessing opaque samples with high spatial resolution.

Drug efflux transporter P-glycoprotein plays an important role in cancer chemotherapy. The nuclear factor-κB (NF-κB) transcription factors play critical roles in development and progression of cancer. In this study, the effects of natural compounds that can inhibit NF-κB activation on the function of P-glycoprotein were investigated using human MDR1 gene-transfected KB/MDR1 cells. The accumulation of daunorubicin or rhodamine 123, fluorescent substrates of P-glycoprotein, in KB/MDR1 cells increased in the presence of caffeic acid phenetyl ester (CAPE), licochalcone A, anacardic acid, celastrol, xanthohumol, magnolol, and honokiol in a concentration-dependent manner. In contrast, lupeol, zerumbone, thymoquinone, emodin, and anethol had no effects. The ATPase activities of P-glycoprotein were stimulated by CAPE, licochalcone A, anacardic acid, celastrol, xanthohumol, magnolol, and honokiol. Tumor necrosis factor (TNF)-α stimulated NF-κB activation was inhibited by CAPE, licochalcone A, anacardic acid, and xanthohumol. KB/MDR1 cells were sensitized to vinblastine cytotoxicity by CAPE, licochalcone A, anacardic acid, xanthohumol, magnolol, and honokiol, showing that these natural NF-κB inhibitors reverse multidrug resistance. These results suggest that natural compounds, such as CAPE, licochalcone A, and anacardic acid, have dual inhibitory effects on the anticancer drug efflux transporter P-glycoprotein and NF-κB activation, and may become useful to enhance the efficacy of cancer chemotherapy.

Effects of natural nuclear factor-kappa B inhibitors on anticancer drug efflux transporter human P-glycoprotein.

A robust hydrogel with a reliable deformation region in an aqueous environment is proposed. The gel has a homogeneous network where hydrophilic/hydrophobic components are uniformly distributed. In an aqueous environment, aggregated hydrophobic segments serve as "mechanical fuse links," inhibiting sudden macroscopic fracture. The gel endures threefold stretching for more than 100 cycles in water without mechanical hysteresis.

Takashi Hiroi

Department of Chemistry,
School of Science,
Department of Chemistry, School of Science

University of Tokyo

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

Takashi Hiroi

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Chemistry,School of Science,Department of Chemistry, School of Science

University of Tokyo

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

Department of Chemistry,
School of Science,
Department of Chemistry, School of Science