Phosphorylation of Chitosan

Matevosyan, G. L.; Yukha, Yu. S.; Zavlin, P. M.

doi:10.1023/b:rugc.0000018648.18120.18

Cited by 25 publications

(19 citation statements)

References 1 publication

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“…A detailed study of the literature on the interaction of chitosan with PO 3K 4 ions indicated that chitsoan has the greater affinity to react with PO 3K 4 ions in both acidic and basic solutions and a propensity to undergo phosphorylation under the experimental conditions used in the present study. In studies specifically aimed at phosphorylating chitosan, the reagents used for phosphorylation include P 2 O 5 in methanesulphonic acid ( Nishi et al 1986), H 3 PO 3 or diethyl hydrogen phosphite in formaldehyde (Matevosyan et al 2003) and urea and H 3 PO 4 in dimethylformamide (Yokogawa et al 2001;Wan et al 2003). In these methods, PO approximately 6.0 at the end of the reaction, phosphorylation of chitosan (most probably via schemes (4.1) and (4.2)) was possible.…”

Section: Discussionmentioning

confidence: 99%

Chitosan-mediated crystallization and assembly of hydroxyapatite nanoparticles into hybrid nanostructured films

Kumar

Prakash

Cheang

et al. 2007

J. R. Soc. Interface.

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The synthesis and subsequent assembly of nearly spherical nano-hydroxyapatite (nHA) particles in the presence of trace amounts of the polysaccharide chitosan was carried out employing a wet chemical approach. Chitosan addition during synthesis not only modulated HA crystallization but also aided in the assembly of nHA particles onto itself. Solvent extraction from these suspensions formed iridescent films, of which the bottom few layers were rich in self-assembled nHA particle arrays. The cross-section of these hybrid films revealed compositional and hence structural grading of the two phases and exhibited a unique morphology in which assembled nHA particles gradually gave way to chitosan-rich top layers. Transmission electron microscope and selected area electron diffraction studies suggested that the basal plane of HA had interacted with chitosan, and scanning electron microscope studies of the hybrid films revealed multi-length scale hierarchical architecture composed of HA and chitosan. Phase identification was carried out by X-ray diffraction (XRD) and Rietveld analysis of digitized XRD data showed that the basic apatite structure was preserved, but chitosan inclusion induced subtle changes to the HA unit cell. The refinement of crystallite shape using the Popa method clearly indicated a distinct change in the growth direction of HA crystallites from [001] to [100] with increasing chitosan concentration. The paper also discusses the likelihood of chitosan phosphorylation during synthesis, which we believe to be a pathway, by which chitosan molecules chemically interact with calcium phosphate precursor compounds and orchestrate the crystallization of nHA particles. Additionally, the paper suggests several interesting biomedical applications for graded nHA-chitosan nanostructured films.

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Section: Discussionmentioning

confidence: 99%

Chitosan-mediated crystallization and assembly of hydroxyapatite nanoparticles into hybrid nanostructured films

Kumar

Prakash

Cheang

et al. 2007

J. R. Soc. Interface.

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“…First, the bands of the primary amino groups (3360, 3290, 1595, and 1560 cm -1 ) have disappeared, which suggests that phosphonomethylation of the amino groups may occur when refluxing in the mixture of formaldehyde and phosphorous acid. This can be proven by the appearance of the C-H vibration band (1420 cm -1 ) of the N-phosphomethylated fragments (CH 2 PO(OH) 2 ), [32] the intensity of which increases with an increase in the addition of APTES. Moreover, the intensity of the band that corresponds to CH 2 (1470 cm -1 ) increases, which indicates an increase in the amount of CH 2 after the phosphorylation reaction.…”

Section: Full Papermentioning

confidence: 99%

“…[30] The appearance of primary amino groups -NH 2 can be seen from the weak absorption bands at 3360 (asymmetric stretch) and 3290 cm -1 (symmetric stretch), and scissor vibrations at 1595 and 1560 cm -1 . [31,32] The absorption bands at 1018, 778, and 428 cm -1 are assigned to the Si-O-Si asymmetric stretch, Si-O-Si symmetric stretch, and Si-O-Si bend, respectively. [30,33] This indicates that a hydrolysis and condensation reaction occurred between TEOS and APTES by a sol-gel process to form the silicate network structure.…”

Section: Fourier-transform Infrared (Ftir) Spectramentioning

confidence: 99%

Hydrolytically Stable Phosphorylated Hybrid Silicas for Proton Conduction

Jin

Qiao

Costa

et al. 2007

Adv Funct Materials

112

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A new approach to the synthesis of fully immobilized phosphorus functionalized hybrid proton conductive gels based on phosphonic acid grafting is presented in this paper. The hybrid silicas with different amounts of phosphonic acid have been prepared and characterized using Fourier‐transform infrared spectroscopy, X‐ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis, thermogravimetric analysis, and electrochemical techniques. The proton conductivity of the materials depend strongly on hydration, which increases by four orders of magnitude over the relative humidity (RH) range of 20 to 100 %, up to a maximum of 0.027 S cm–1 at 100 °C and 100 % RH. For the reported samples, proton conduction is believed to occur within a dynamic hydrogen‐bond network formed by functionalized P–OH groups and water molecules by the Grotthuss mechanism. However, the proton conductive sites (P–OH) are likely to be partially immobilized by strong protonic receptors (N atoms in amines), which reduces the free P–OH groups and restricts proton transfer. Hydration may cause a bonding structural rearrangement, which results in more free P–OH groups as active proton conductive sites and, therefore, greatly increased proton conductivity is observed.

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“…Phosphate derivatives of chitosan may also be obtained by interpolymer linkage of chitosan with tripolyphosphate or polyphosphate [15,16]. Few work deals with the introduction of ␣-aminomethylphosphonic acid functions onto chitosan using the Kabachnik-fields reactions [17,18] in the spite of the interest of such groups [4][5][6].…”

Section: Introductionmentioning

confidence: 99%