Modified chitosan carrying phosphonic and alkyl groups

Ramos, Viviana

doi:10.1016/s0144-8617(02)00211-4

Cited by 102 publications

(34 citation statements)

References 18 publications

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“…The peaks at 2.702, 3.449, and 4.434 ppm are assigned to the H-2, H-3, and H-1 of chitosan (30). The signals of H-4, H-5, H-6 of chitosan cannot be resolved due to overlapping with those of NIPAAm.…”

Section: Resultsmentioning

confidence: 97%

A Thermoresponsive Chitosan−NIPAAm/Vinyl Laurate Copolymer Vector for Gene Transfection

et al. 2005

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A carboxyl-terminated N-isopropylacrylamide/vinyl laurate (VL) copolymer was prepared and coupled with chitosan (molecular weight = 2000) to produce a chitosan-NIPAAm/VL copolymer (PNVLCS) vector. The aqueous solution of PNVLCS displayed an obvious thermoresponsive behavior with a lower critical solution temperature (LCST) about 26 degrees C. The transmission electron microscopy (TEM) showed that the size of PNVLCS/DNA complexes varied with charge ratios (+/-), and the smaller nanoparticles were formed at higher charge ratios. DLS revealed that the size of complex particles was dependent on temperature. The results of temperature-variable circular dichroism (CD), UV, and electrophoresis retardation indicated that at lower charge ratios, DNA in the complexes assume a B conformation, whereas increasing charge ratios caused B --> C type conformation transformation; the dissociation-formation of PNVLCS/DNA complexes could be tuned by varying temperature: at 37 degrees C, the collapse of PNIPAAm in PNVLCS was favorable for the formation of compact complexes, shielding more DNA from exposure; at 20 degrees C, the hydrated and extended PNIPAAm chains facilitated the unpacking of DNA from PNVLCS, increasing the exposure of DNA. PNVLCS was used to transfer plasmid-encoding beta-galactosidase into C2C12 cells. The level of gene expression could be controlled by varying incubation temperature. The transfection efficiency of PNVLCS was well improved by temporarily reducing culture temperature to 20 degrees C, whereas naked DNA and Lipofectamine 2000 did not demonstrate the characteristics of thermoresponsive gene transfection.

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Section: Resultsmentioning

confidence: 97%

A Thermoresponsive Chitosan−NIPAAm/Vinyl Laurate Copolymer Vector for Gene Transfection

et al. 2005

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“…It has been reported in different studies that C12 alkyl chains grafted onto the chitosan backbone lead to formation of stable gels (Iversen et al, 1997;Ramos et al, 2003). Rinaudo et al have shown from a series of alkylated chitosan derivatives that the C12 alkyl chain was the optimal chain length for forming a stable gel (Rinaudo et al, 2005).…”

Section: Poli Gel Blend Characterization-lauric Aldehyde Vs Lauric Cmentioning

confidence: 99%

Chitosan–phospholipid blend for sustained and localized delivery of docetaxel to the peritoneal cavity

Zahedi

Souza

Piquette-Miller

et al. 2009

International Journal of Pharmaceutics

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“…For example, the introduction of an alkyl chain onto water-soluble modified chitosan (N-methylene phosphonic chitosan) introduces both hydrophobic and hydrophilic side chains. The presence of alkyl groups in N-lauryl-N-methylene phosphonic chitosan weakens the hydrogen bond and provides good solubility in organic solvents (Ramos et al, 2003). In addition, chitosan that is bound with sialic acid using p-formylphenyl-a-sialoside by reductive N-alkylation is a potent inhibitor of the influenza virus and is used as a blocking agent for acute rejection (Gamian et al, 1991).…”

Section: Chitosan and Its Derivativesmentioning

confidence: 99%