New paramagnetic supramolecular adducts for MRI applications based on non-covalent interactions between Gd(III)-complexes and β- or γ-cyclodextrin units anchored to chitosan

Aime, Silvio; Gianolio, Eliana; Uggeri, Fulvio; Tagliapietra, Silvia; Cravotto, Giancarlo

doi:10.1016/j.jinorgbio.2005.12.003

Cited by 29 publications

(12 citation statements)

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“…[59][60][61] The relaxivity enhancements observed upon formation of the supramolecular adducts with bCD and with pbCD ( Table 1) are similar to values reported for related systems. [32,41,44,60,[62][63][64] The rather limited enhancement obtained with pbCD, in spite of its high molecular weight (10 3 -2.6 10 3 KDa), is classical for this linear polymer and has been assigned to the predominance of the segmental motions over the rotational correlation time, which becomes independent of molecular weight above 10 KDa. [65] Nevertheless, these results demonstrate that adamantane-functionalized 5 forms inclusion complexes with bCD and its polymeric form; this was a prerequisite for the following study on the engineered supramolecular nanoassemblies.…”

Section: Resultsmentioning

confidence: 99%

“…In this context the host–guest type interactions with cyclodextrin (CD) have been exploited to obtain large supramolecular structures39, 40 and especially high‐molecular‐weight adducts of poly‐β‐cyclodextrin (pβCD) (average MW of 6–130 KDa) with suitably functionalized chelates, leading to an efficient relaxation enhancement 32. 41–45 However, all the previously described systems using CD have been limited to a moderate β‐cyclodextrin (βCD) content and a consequent low amount of loaded Gd III .…”

Section: Introductionmentioning

confidence: 99%

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High‐Relaxivity Magnetic Resonance Imaging (MRI) Contrast Agent Based on Supramolecular Assembly between a Gadolinium Chelate, a Modified Dextran, and Poly‐β‐Cyclodextrin

Battistini¹,

Gianolio²,

Gref³

et al. 2008

Chemistry A European J

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Nanosized contrast agents have great potential in magnetic resonance molecular imaging applications for clinical diagnosis. This study proposes new nanoparticles spontaneously formed under mild conditions and composed of a noncovalent adduct between a gadolinium complex, a polymer of beta-cyclodextrin (pbetaCD: MW 1.5 x 10(6) g mol(-1)) and a dextran grafted with alkyl chains (MD). The formation of this supramolecular nanoassembly is based upon a "lock-and-key" recognition process in which the hydrophobic alkyl chains of MD and the adamantyl moieties of macrocyclic Gd(III) chelates are included in the cavities of pbetaCD. The large number of betaCDs contained in the pbetaCD resulted in the formation of 200 nm diameter nanoparticles, each entrapping 1.8 x 10(5) molecules of a low-molecular-weight Gd complex. This system, which exhibits a great relaxivity enhancement (48.4 mM(-1) s(-1), at 20 MHz and 37 degrees C) compared to the Gd(III) chelate itself (5.2 mM(-1) s(-1)), appears to be a promising strategy for the in vivo targeted delivery of Gd(III) complexes. The mechanisms of particle formation, conjugation strategies, and relaxometric characterizations in the field of contrast-enhanced magnetic resonance imaging are discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High‐Relaxivity Magnetic Resonance Imaging (MRI) Contrast Agent Based on Supramolecular Assembly between a Gadolinium Chelate, a Modified Dextran, and Poly‐β‐Cyclodextrin

Battistini¹,

Gianolio²,

Gref³

et al. 2008

Chemistry A European J

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100

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“…A capacidade estruturadora das CDs foi ainda estudada recentemente na qualidade de 'chaperones' artificiais para a renaturação de uma proteína 74 . A associação das CDs à química dos polímeros tem permitido uma ampla faixa de aplicações que envolvem, por exemplo, o desenvolvimento de um sistema para a liberação de insulina com aplicação nasal 75 , o uso de nanoesferas em sistemas de floculação/ sorção 76 , o estudo da pervaporação de misturas de benzeno com cicloexano 77 e o desenvolvimento de adutos supramoleculares paramagnéticos para aplicações como agentes de contraste em imagem por ressonância magnética 78 . Merece destaque ainda o uso de CDs para o desenvolvimento de receptores moldados especialmente para determinados substratos pelo uso da estratégia da impressão molecular ("molecular imprinting").…”

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Propriedades e aplicações recentes das ciclodextrinas

Venturini¹,

Nicolini²,

Machado³

et al. 2008

Quím. Nova

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Recebido em 22/9/06; aceito em 22/5/07; publicado na web em 26/2/08 PROPERTIES AND RECENT APPLICATIONS OF CYCLODEXTRINS. Cyclodextrins (CDs) are cyclic oligosaccharides comprised of six or more glucose units connected by α-1,4 bonds. They have hydrophobic cavities with a hydrophilic exterior, and are versatile receptors for a variety of substrates. This ability allows them to be applied in many fields, as distinct as supramolecular chemistry, nanotechnology, pharmaceuticals, green chemistry, agrochemicals, analytical chemistry, toiletries, foods, and cosmetics. This review summarizes several aspects related to the physico-chemical properties of CDs and discusses their potential applications illustrated by recent examples. The prospects for their use in several areas are also described.Keywords: cyclodextrins; molecular recognition; inclusion complexes. INTRODUÇÃOAo longo das últimas décadas, as ciclodextrinas (CDs) vêm despertando grande interesse na comunidade científica e na química de macromoléculas, sendo descritas como "moléculas sedutoras, atraindo a atenção dos investigadores tanto no campo de pesquisa como no campo de tecnologias aplicadas" 1 . Szejtli afirmou que "dentre todas as moléculas receptoras em potencial, as CDs parecem ser as mais importantes" 2 . Tal afirmação deriva primordialmente do fato das mesmas, por pertencerem à família dos oligossacarídeos macrocíclicos, formarem complexos do tipo receptor-substrato servindo como um ambiente único para reações químicas 3 e possuírem a habilidade para formar complexos de inclusão com uma variedade de substâncias que têm suas propriedades alteradas pela complexação 4 . Por este motivo, as CDs vêm sendo muito utilizadas em produtos industriais, tecnológicos e em métodos analíticos. Como os efeitos tóxicos podem ser eliminados ou reduzidos pela seleção da CD apropriada, as CDs podem ser utilizadas como ingredientes de fármacos, em alimentos ou em cosméticos 2 . As CDs são formadas durante a ação de enzimas denominadas como CD glicosiltransferases (CGTases) sobre o amido 5 , sendo este o processo utilizado na produção industrial das mesmas. Usualmente, os polissacarídeos servem como precursores de oligos-sacarídeos cíclicos. Como resultado, a variedade de oligossacarídeos cíclicos naturais ou semi-sintéticos é limitada 6 . As mais importantes CDs apresentando ocorrência natural são as α-, β-e γ-CDs, que possuem 6, 7 e 8 monômeros de glicose, respectivamente (Figura 1). As características estruturais das mesmas são conhecidas com base em investigações por cristalografia de raios-X no estado sólido e por estudos de RMN em solução. Estas moléculas possuem forma assemelhada a um cone, com uma cavidade de 7,9 Å de profundidade. Os diâmetros superior e inferior da cavidade das CDs são 4,7 e 5,3 Å para a α-CD, 6,0 e 6,5 Å para a β-CD e 7,5 e 8,3 Å para a γ-CD 7. As CDs modificadas surgiram a partir da tentativa de alterar ou melhorar suas estruturas a fim de obter complexos de inclusão adequados a vários setores, como industrial, alimentício e farmacêutico 8 , e...

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“…An example of water-soluble β- and γ-CD/chitosan derivatives have been studied for binding Gd(III) chelates that bear hydrophobic substituents and negative charges [ 35 ]. These bio-polymers were easily prepared in two reaction steps by reacting CDs with maleic anhydride followed by activation with carbodiimide to form amide linkages with amino groups of chitosan.…”

Section: Reviewmentioning

confidence: 99%

Enabling technologies and green processes in cyclodextrin chemistry

Cravotto¹,

Caporaso²,

Jicsinszky³

et al. 2016

Beilstein J. Org. Chem.

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SummaryThe design of efficient synthetic green strategies for the selective modification of cyclodextrins (CDs) is still a challenging task. Outstanding results have been achieved in recent years by means of so-called enabling technologies, such as microwaves, ultrasound and ball mills, that have become irreplaceable tools in the synthesis of CD derivatives. Several examples of sonochemical selective modification of native α-, β- and γ-CDs have been reported including heterogeneous phase Pd- and Cu-catalysed hydrogenations and couplings. Microwave irradiation has emerged as the technique of choice for the production of highly substituted CD derivatives, CD grafted materials and polymers. Mechanochemical methods have successfully furnished greener, solvent-free syntheses and efficient complexation, while flow microreactors may well improve the repeatability and optimization of critical synthetic protocols.

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New paramagnetic supramolecular adducts for MRI applications based on non-covalent interactions between Gd(III)-complexes and β- or γ-cyclodextrin units anchored to chitosan

Cited by 29 publications

References 44 publications

High‐Relaxivity Magnetic Resonance Imaging (MRI) Contrast Agent Based on Supramolecular Assembly between a Gadolinium Chelate, a Modified Dextran, and Poly‐β‐Cyclodextrin

High‐Relaxivity Magnetic Resonance Imaging (MRI) Contrast Agent Based on Supramolecular Assembly between a Gadolinium Chelate, a Modified Dextran, and Poly‐β‐Cyclodextrin

Propriedades e aplicações recentes das ciclodextrinas

Enabling technologies and green processes in cyclodextrin chemistry

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