The aggregative behavior of hydrophobically modified chitosans with high substitution degree in aqueous solution

Ortona, Ornella; D’Errico, Gerardino; Mangiapia, Gaetano; Ciccarelli, Donato

doi:10.1016/j.carbpol.2008.01.009

Cited by 49 publications

(37 citation statements)

References 29 publications

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“…The largest part of them is related to the ability of this polymer to bind a lot of substances for the contemporary presence on its backbone of hydrophobic units, the acetamide groups, and hydrophilic units, the amino groups, and also to the capacity of chitosan to self-aggregate giving rise to gel systems [20].…”

Section: Natural Polymeric Surfactantsmentioning

confidence: 99%

Surface active properties of chitosan and its derivatives

Elsabeé

Morsi

Al‐Sabagh

2009

Colloids and Surfaces B: Biointerfaces

146

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Section: Natural Polymeric Surfactantsmentioning

confidence: 99%

Surface active properties of chitosan and its derivatives

Elsabeé

Morsi

Al‐Sabagh

2009

Colloids and Surfaces B: Biointerfaces

146

View full text Add to dashboard Cite

“…41,79 A recent work by Ortona et al have showed that the short aliphatic chains on the chitosan backbone is not able to promote an efficient hydrophobic interaction among chains. 72 Thus, it suggests that the hydrophobic contribution for the aggregation process is cooperative, which would involve the sum of the individual hydrophobic sites. This might justify the fact that chitin and chitosan aggregates with block distribution of acetyl group are more stable and more resistant to swelling than the uniformly acetylated polymers.…”

mentioning

confidence: 99%

“…To date, a number of contributing components to chitin and chitosan solubility have been reported, 17,[71][72][73] such as intramolecular hydrogen bonding, hydrophobic interactions and electrostatic forces. To address these issues, six 20-ns simulations of crystal-like nanoparticles (starting from a two-fold helix conformation and packed in anti-parallel fashion setup) were carried out at the same pH and acetylation used for the solvated chains.…”

mentioning

confidence: 99%

Chitosan molecular structure as a function of N‐acetylation

2011

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Molecular dynamics simulations have been carried out to characterize the structure and solubility of chitosan nanoparticle-like structures as a function of the deacetylation level (0, 40, 60, and 100%) and the spatial distribution of the N-acetyl groups in the particles. The polysaccharide chains of highly N-deacetylated particles where the N-acetyl groups are uniformly distributed present a high flexibility and preference for the relaxed two-fold helix and five-fold helix motifs. When these groups are confined to a given region of the particle, the chains adopt preferentially a two-fold helix with ϕ and ψ values close to crystalline chitin. Nanoparticles with up to 40% acetylation are moderately soluble, forming stable aggregates when the N-acetyl groups are unevenly distributed. Systems with 60% or higher N-acetylation levels are insoluble and present similar degrees of swelling regardless the distribution of their N-acetyl groups. Overall particle solvation is highly affected by electrostatic forces resulting from the degree of acetylation. The water mobility and orientation around the polysaccharide chains affects the stability of the intramolecular O3-HO3((n)) ···O5((n +) (1)) hydrogen bond, which in turn controls particle aggregation.

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“…Biocompatibility and biodegradability of starting materials, together with their large availability in nature, are added values for composites intended to perform medical and biobased functions. By virtue of straightforward chemical modifications (Ortona et al 2008), introduction of properly designed inorganic nanostructures (Duarte et al 2012;Ruiz-Hitzky et al 2013), or adopting different fabrication procedures (Suh et al 2000;Calvert 2001; Liu Tsang and Bhatia 2004;Ryan et al 2006), material properties can be tailored to meet specific needs (Fox et al 2013;Connell et al 2014). Among polysaccharides, chitosan and hyaluronic acid have been extensively studied and adopted in the formulation of nano-hybrid hydrogels, composites, and drug carriers (Vallés-Lluch et al 2013;Ha et al 2006;Berthold et al 1996;Agnihotri et al 2004).…”

Section: Introductionmentioning

confidence: 99%

The effect of charge on the release kinetics from polysaccharide–nanoclay composites

et al. 2015

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The objective of this study was to integrate inorganic halloysite nanotubes (HNT) with chitosan and hyaluronic acid to obtain hybrid nanocomposites with opposing charges and to investigate their potential in the controlled release of drug model probes. Two oppositely charged polysaccharides, chitosan and hyaluronic acid, were selected for their biocompatibility and their importance in biomedical applications. The high surface area and the hollow nanometric-sized lumen of HNT allowed for the efficient loading of rhodamine 110 and carboxyfluorescein, used as models for oppositely charged drugs. In the case of chitosan, the preparation of the nanocomposite was carried out exploiting the electrostatic interaction between the polymer and HNT in water, while with hyaluronic acid, a covalent functionalization strategy was employed to couple the polymer with the clay. Nanocomposites were characterized with thermal, microscopic, and spectroscopic techniques, and the release kinetics of the model compounds was assessed by fluorescence measurements. The release curves were fitted with a model able to account for the desorption process from the external and the internal halloysite surfaces. The results show that both polymeric coatings alter the release of the probes, indicating a key role of both charge and coating composition on the initial and final amount of released dye, as well as on the rate of the desorption process.

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The aggregative behavior of hydrophobically modified chitosans with high substitution degree in aqueous solution

Cited by 49 publications

References 29 publications

Surface active properties of chitosan and its derivatives

Surface active properties of chitosan and its derivatives

Chitosan molecular structure as a function of N‐acetylation

The effect of charge on the release kinetics from polysaccharide–nanoclay composites

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