Thermotropic Cholesteric Liquid Crystals in Ester Derivatives of Hydroxypropylcellulose

Kosho, Hiroshi; Hiramatsu, Sotaro; Nishi, Tohru; Tanaka, Yasuyuki; Kawauchi, Susumu; Watanabe, Junji

doi:10.1088/0954-0083/11/1/004

Cited by 24 publications

(32 citation statements)

References 24 publications

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“…Within each layer, the ultrastructure comprises parallel microfibrillae that are offset to the left by a standard distance at each successive level to ultimately form 360 degree helicoidal stacks, that define the thickness of the layer or its pitch. Such crystals are inherently self-organising with regard to the offset in alignment of successive levels, and some classes of crystals vary in pitch with temperature ( Kosho et al , 1999 ). The optical properties of these microfibrillae are shared with cholesteric liquid crystals ( Neville & Caveney, 1969 ).…”

Section: Discussionmentioning

confidence: 99%

Functional implications of temperature‐correlated colour polymorphism in an iridescent, scarabaeine dung beetle

Davis

Brink

Scholtz

et al. 2008

Ecological Entomology

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1. In many Coleoptera, iridescent colouration is generated by exoskeleton ultra-structure, within which multilayer interference reflects only certain wavelengths. Published work indicates that the colour polymorphism shown by some iridescent beetles is under genetic control. However, the present study suggests environmental involvement in the polymorphic southern African dung beetle, Gymnopleurus humanus Macleay.2. At 24 study sites across a 1000-km latitudinal temperature gradient, population samples of G. humanus were dominated by blue individuals in the cooler south, by cupreous individuals in the warmer north, and by locally co-occurring blue, green and cupreous individuals in intermediate situations.3. Using digital reflectance spectrophotometry, we measured wavelength intensity values across the visible spectrum (400 -800 nm) and used the 70 measured specimens to estimate maximum reflectance from a further 3912 beetles. Differences in mean reflectance values between 24 populations were strongly correlated with average annual temperatures at study sites.4. Much stronger correlations between mean reflectance values and average temperatures of the cool dry season months suggest that the cross-climatic patterns may be related to interaction between breeding seasonality and development under different cooler temperatures.5. Published evidence suggests that inherent physical properties of cholesteric liquid crystals and their responses to different thermal conditions could, potentially, generate the different exocuticle ultra-structure responsible for different reflected colour wavelengths. Furthermore, colour polymorphism could be advantageous across a gradient from cooler to warmer climate as a result of the different thermal properties of different colours.6. Given the correlation with temperature, it is predicted that the prevailing reflected colour balance in southern populations would shift in response to global climatic change.

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Section: Discussionmentioning

confidence: 99%

Functional implications of temperature‐correlated colour polymorphism in an iridescent, scarabaeine dung beetle

Davis

Brink

Scholtz

et al. 2008

Ecological Entomology

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“…The available HPC was hydrolyzed to low molecular weight HPC [26] (M n =70 000 gmol −1 and PDI=1.43 according to SEC with THF as mobile phase). Molar substitution of propoxy groups (MS HP ) 3.0 was determined using 1 H nuclear magnetic resonance (NMR).…”

Section: Methodsmentioning

confidence: 99%

Thermosensitive biotinylated hydroxypropyl cellulose-based polymer micelles as a nano-carrier for cancer-targeted drug delivery

et al. 2014

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In this article, we report the synthesis of a novel amphiphilic hydroxypropyl cellulose-based polymer (HPC-PEG-Chol) that contained poly (ethylene glycol) and cholesterol-containing moieties with specific degrees of substitution. The resulting polymer was subsequently converted to a biotin conjugate (HPC-PEG-Chol-biotin), to develop a new potential cancer-targeted drug delivery system. The biotin conjugate was used to prepare micelles via the dialysis method. The polymeric micelles in aqueous solution presented a lower critical solution temperature (LCST) of 39.8 o C. The critical micelle concentration (CMC) values of the polymeric micelles at 25 and 45°C were evaluated to be about 0.32 and 0. 25 g/L, respectively. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses of the micelles revealed the spherical shapes of the micelles, with 84 nm mean diameters that increased with the increase of the temperature above LCST. The hydrophobic anticancer drug paclitaxel (PTX) was loaded in the micelles and the in vitro release behaviors of PTX were investigated at different temperatures. The release profile of PTX from the polymeric micelles revealed a thermosensitivity, since its release rate was higher at 41°C than at 37°C. Fluorescent microscopy analyses confirm that the PTX-loaded HPC-PEG-Cholbiotin is superior in cellular uptake, with very strong adsorption to both HeLa and MDA-MB-231 cancer cell lines. MTT assay in normal cells indicated that HPC-PEG-Chol-biotin micelles have great potential to be safely used in tumortargeting chemotherapy.

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“…Temperature dependence of the cholesteric pitch has also been examined on other thermotropic cellulose derivatives and represented by the following equation (Kosho et al 1999):…”

Section: Cholesteric Mesophasesmentioning

confidence: 99%

Preparation and cholesteric mesophase properties of (Butyl-co-pentyl) propylcellulose

2006

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Butyl and pentyl ether derivatives of (2-hydroxypropyl) cellulose (HPC) and butyl/pentyl mixed ethers of HPC (BPPC) with different alkyl compositions were prepared in nonaqueous solution and their thermotropic cholesteric properties examined. The temperature dependence and the composition dependence of the optical pitch, nP, were then determined for all of the ether derivatives. The molecular conformation and chirality of BPPC appeared to be to be variably smooth with the side chain composition of the polymer. The response rate of cholesteric configurational change of the thermotropic mesophases arising from a temperature jump from 45 to 75°C, was also determined. The transformation of the cholesteric mesophase formed by an equimolar ether derivative (BP-50) was faster than that of the cholesteric one formed by a single-alkyl (pentyl) ether derivative (BP-0). This seemed to be a general result reflecting a pseudo-copolymer effect of cellulose derivatives on the properties of their thermotropic cholesteric mesophases.

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Thermotropic Cholesteric Liquid Crystals in Ester Derivatives of Hydroxypropylcellulose

Cited by 24 publications

References 24 publications

Functional implications of temperature‐correlated colour polymorphism in an iridescent, scarabaeine dung beetle

Functional implications of temperature‐correlated colour polymorphism in an iridescent, scarabaeine dung beetle

Thermosensitive biotinylated hydroxypropyl cellulose-based polymer micelles as a nano-carrier for cancer-targeted drug delivery

Preparation and cholesteric mesophase properties of (Butyl-co-pentyl) propylcellulose

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