Chitosan Chemistry and Pharmaceutical Perspectives

Kumar, M. N. V. Ravi; Müzzarelli, Riccardo A.A.; Muzzarelli, Corrado; Sashiwa, Hitoshi; Domb, Abraham J.

doi:10.1021/cr030441b

Cited by 2,562 publications

(1,069 citation statements)

References 642 publications

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“…39 Chitosan has drawn significant attention due to its attractive mechanical properties, sustainability, biocompatibility, and antimicrobial properties. 40,41,42 The backbone of chitosan consists of N-acetylglucosamine and Dglucosamine units of which the latter contain primary amines which make the polymer pHresponsive. Chitosan is water-soluble when the amines are protonated, as shown in Figure 1, roughly below the pKa of the ammonium ion, between 6.0 and 6.5.…”

Section: Introductionmentioning

confidence: 99%

Water-Resistant, Transparent Hybrid Nanopaper by Physical Cross-Linking with Chitosan

et al. 2015

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ABSTRACT. One of the major, but often overlooked, challenges towards high end applications of nanocelluloses is to maintain their mechanical stability under hydrated conditions. As such, permanent covalent crosslinking or surface hydrophobization are viable solutions provided that neither processability nor interfibrillar bonding is compromised. Here we show an alternative based on physical crosslinking of nanofibrillated cellulose (NFC, also denoted as microfibrillated cellulose, MFC, and cellulose nanofibers, CNF) with chitosan for the preparation of transparent films. Transparency (~ 80 % throughout the visible spectrum) is achieved by suppressing aggregation and carefully controlling the mixing conditions: Chitosan dissolves in aqueous medium at low pH and under these conditions the NFC/chitosan mixtures form easily processable hydrogels.A simple change in the environmental conditions (i.e. an increase of pH) reduces hydration of chitosan promoting multivalent physical interactions between NFC and chitosan over those with water, resulting effectively in crosslinking. Films of NFC/chitosan 80/20 w/w show excellent mechanical properties in the wet state, with a tensile modulus of 4 and 14 GPa at low (0.5 %) and large (16 %) strains, respectively and an ultimate strength of 100 MPa (with corresponding maximum strain of 28 %). Remarkably, a strength of 200 MPa (with maximum strain of 8%) is measured at 50 % air relative humidity. We expect that the proposed, simple concept opens new pathways toward NFC-based material utilization in wet or humid conditions, a challenge that has remained unresolved.

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Section: Introductionmentioning

confidence: 99%

Water-Resistant, Transparent Hybrid Nanopaper by Physical Cross-Linking with Chitosan

et al. 2015

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“…Higher deacetylation degree, more than 95%, are high cost and are generally reserved for biomedical applications. 3,4 Chit is of commercial interest due to its high percentage of nitrogen, amino and hydroxyl groups on their chemical structure which act as chelation sites for metal ions. So, in the literature, there are many reported works taking advantage of the complexing ability of chitosan and some of its derivatives with polyvalent metal ion to remediate various hazardous waste waters.…”

Section: Introductionmentioning

confidence: 99%

Chemical equilibrium in the complexation of first transition series divalent cations Cu2+, Mn2+ and Zn2+ with chitosan

Hernández¹,

Yola²,

Mercê³

2007

J. Braz. Chem. Soc.

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O presente estudo forneceu dados para o cálculo das constantes de estabilidade formadas em um sistema aquoso e HCl contendo quitosana e cátions Cu 2+ , Mn 2+ e Zn 2+ . Os diagramas de espécies foram gerados para demonstrar como o pH influencia esses equilíbrios estudados por titulações potenciométricas e espectrofotométricas. Os sólidos extraídos dessas soluções aquosas em HCl foram estudados por espectroscopia no infravermelho. A quitosana complexa-se com os cátions Cu 2+ , Mn 2+ e Zn 2+ a pHs >4 >5 e >2 respectivamente, na razão ligante:metal, 1:1. As constantes de estabilidade calculadas para ML apresentaram a seguinte ordem de estabilidade: Cu 2+ >Zn 2+ >Mn 2+ . Algumas estruturas para os possíveis complexos formados foram sugeridas envolvendo ambos os átomos de N e/ou O como sítios quelantes de uma ou duas unidades monoméricas do biopolímero estudado.This study provided the data for calculating the stability constants formed in the aqueous HCl equilibrium of chitosan and Cu 2+ , Mn 2+ and Zn 2+ , and determined the species distribution diagrams to show the influence of pH in the complexation systems based on data obtained from potentiometric and spectrophotometric titrations. The solid complexes further obtained from these aqueous HCl systems, were investigated by infrared spectroscopy. It was verified that chitosan coordinated with the cations Cu 2+ , Mn 2+ and Zn 2+ at pHs >4 >5 and >2 respectively, in ligand to metal ratio of 1:1. The logarithms of the binding constants for ML species presented the following stability order: Cu 2+ >Zn 2+ >Mn 2+ . Some possible complexed structures were suggested having both N and/or O atoms as binding sites with one or two monomers of the biopolymer studied.

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“…[11a] On the other hand, the selected coating materials should have good solubility at pH values necessary to precipitate MNPs, i.e., in situ coating of MNPs with chitosan was problematic due to its poor solubility at the desired pH values. [380] The precipitating agents are often synthetic polymers such as PEG, PVA, poly (acrylic acid) (PAA), poly (methylacrylic acid) (PMAA), poly (lactic acid) (PLA), polyvinylpyrrolidone (PVP), PEI and biopolymers such as carbohydrates (dextran, chitosan, alginate, arabinogalactan). In contrast to in situ approach, within the post synthesis strategy, bare magnetic cores will be introduced by coating materials onto their surface through ligand exchange, [140,381] direct grafting [382] or hydrophobic interactions.…”

Section: Coatings Approaches Of Mnpsmentioning

confidence: 99%

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

Mosayebi

Kiyasatfar

Laurent

2017

Adv Healthcare Materials

193

171

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In order to translate nanotechnology into medical practice, magnetic nanoparticles (MNPs) have been presented as a class of non‐invasive nanomaterials for numerous biomedical applications. In particular, MNPs have opened a door for simultaneous diagnosis and brisk treatment of diseases in the form of theranostic agents. This review highlights the recent advances in preparation and utilization of MNPs from the synthesis and functionalization steps to the final design consideration in evading the body immune system for therapeutic and diagnostic applications with addressing the most recent examples of the literature in each section. This study provides a conceptual framework of a wide range of synthetic routes classified mainly as wet chemistry, state‐of‐the‐art microfluidic reactors, and biogenic routes, along with the most popular coating materials to stabilize resultant MNPs. Additionally, key aspects of prolonging the half‐life of MNPs via overcoming the sequential biological barriers are covered through unraveling the biophysical interactions at the bio–nano interface and giving a set of criteria to efficiently modulate MNPs' physicochemical properties. Furthermore, concepts of passive and active targeting for successful cell internalization, by respectively exploiting the unique properties of cancers and novel targeting ligands are described in detail. Finally, this study extensively covers the recent developments in magnetic drug targeting and hyperthermia as therapeutic applications of MNPs. In addition, multi‐modal imaging via fusion of magnetic resonance imaging, and also innovative magnetic particle imaging with other imaging techniques for early diagnosis of diseases are extensively provided.

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Chitosan Chemistry and Pharmaceutical Perspectives

Cited by 2,562 publications

References 642 publications

Water-Resistant, Transparent Hybrid Nanopaper by Physical Cross-Linking with Chitosan

Water-Resistant, Transparent Hybrid Nanopaper by Physical Cross-Linking with Chitosan

Chemical equilibrium in the complexation of first transition series divalent cations Cu2+, Mn2+ and Zn2+ with chitosan

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

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