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  • 1
    Electronic Resource
    Electronic Resource
    Visualization of PEO-PBLA-Pyrene Polymeric Micelles by Atomic Force Microscopy (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1721-1726 
    Details
    ISSN: 1573-904X
    Keywords: polymeric micelles ; AFM ; DLS ; pyrene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To directly visualize and evaluate the aqueous block copolymeric micelles, poly(ethylene oxide)-poly(β-benzyl L-aspartate) (PEO-PBLA) chemically conjugated with pyrene fluorescence molecule, by nanotechnology of atomic force microscopy (AFM). Methods. The block copolymers' PEO-PBLA-Pyrene was first synthesized by reacting with pyrene sulfonyl chloride and PEO-PBLA in tetrahydrofuran (THF) solution and were identified by GPC reflect index, UV and fluorescence detectors. The characterization of physical and chemical properties of PEO-PBLA-Pyrene polymeric micellar solution were examined by the dynamic light scattering (DLS) and critical micelles concentrations (CMC). In addition, the nanotechnology of AFM was used to directly visualize the size and shape of nanopolymeric micelles. Results. The pyrene fluorescence molecule were successfully conjugated at the amino group of the end of PBLA chain by GPC with three different detectors. The size of the aqueous PEO-PBLA-Pyrene polymeric micelles was detected around 57 nm with unimodal distribution by DLS measurement. As a result of this finding, the CMC test was also found out that the fluorescence intensity was increasing around 0.01 ∼ 0.05 mg/ml. Using AFM evaluation of polymeric micellar solution, the morphology of aqueous PEO-PBLA-Pyrene polymeric micelles was observed on round shape and with the narrow dispersity of size range 50 ∼ 80 nm. Conclusions. The presence of PEO-PBLA copolymers with pyrene in an aqueous system formed in a spherical and nano range of polymeric micelles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011908728838
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  • 2
    Electronic Resource
    Electronic Resource
    “On–Off” Thermocontrol of Solute Transport. I. Temperature Dependence of Swelling of N-Isopropylacrylamide Networks Modified with Hydrophobic Components in Water (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 531-537 
    Details
    ISSN: 1573-904X
    Keywords: thermosensitivity ; hydrogels ; N-isopropylacrylamide ; interpenetrating polymer networks ; surface deswelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The swelling in water, as a function of temperature, of two series of N-isopropylacrylamide (NIPA Am) polymer networks was studied. In the first series, n-butylmethacrylate (BMA) was copolymerized with NIPA Am, and in the second, polytetramethylene ether glycol (PTMEG) was incorporated into NIPAAm network as a chemically independent interpenetrating network. With increasing BMA content in the poly(NIPAAm-co-BMA) network, the gel collapse point was lowered and the gels deswelled in a more gradual manner with increasing temperature. In the interpenetrating polymer networks (IPN) system, the gel collapse point was not significantly changed by the amount of incorporated PTMEG. In DSC thermograms of swollen samples, the shape and onset temperature of the endothermic peak corresponded to the gel deswelling behavior and gel collapse point. The temperature dependence of equilibrium swelling in water was shown to be a function of the gel composition in both network series. The synthesized networks formed a dense surface layer as the temperature increased past the gel collapse point. This dense layer retarded water efflux and thereby resulted in water pockets at the membrane surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015871732706
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrogels: Swelling, Drug Loading, and Release (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 283-290 
    Details
    ISSN: 1573-904X
    Keywords: hydrogels ; swelling ; loading ; release kinetics ; functional polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. The desired kinetics, duration, and rate of solute release from hydrogels are limited to specific conditions, such as hydrogel properties, amount of incorporated drug, drug solubility, and drug–polymer interactions. This review summarizes the compositional and structural effects of polymers on swelling, loading, and release and approaches to characterize solute release behavior in a dynamic state. A new approach is introduced to compensate drug effects (solubility and loading) with the release kinetics by varying the structure of heterogeneous polymers. Modulated or pulsatile drug delivery using functional hydrogels is a recent trend in hydrogel drug delivery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015887213431
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    Paper (German National Licenses)
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