Dendrimer intercalation in layered double hydroxides

Layered double hydroxides (LDHs) are versatile materials used for intercalating bioactive molecules in the fields of pharmaceuticals, nutraceuticals and cosmetics, with the purpose of protecting them from degradation, enhancing their water solubility to increase bioavailability and improving their pharmacokinetic properties and formulation stability. Moreover, LDHs are used in various technological applications to improve stability and processability. The crystal chemistry of hydrotalcite-like compounds was investigated by X-ray powder diffraction (XRPD), automated electron diffraction tomography (ADT) and thermogravimetric analysis (TGA)-GC-MS to shed light on the mechanisms involved in ion exchange and absorption of contaminants, mainly carbonate anions. For the first time, ADT allowed a structural model of LDH_NO3 to be obtained from experiment, shedding light on the conformation of nitrate inside LDH and on the loss of crystallinity due to the layer morphology. The ADT analysis of a hybrid LDH sample (LDH_EUS) clearly revealed an increase in defectivity in this material. XRPD demonstrated that the presence of carbonate can influence the intercalation of organic molecules into LDH, since CO3 -contaminated samples tend to adopt d spacings that are approximate multiples of the d spacing of LDH_CO3 . TGA-GC-MS allowed intercalated and surface- adsorbed organic molecules to be distinguished and quantified, the presence and amount of carbonate to be confirmed, especially at low concentrations (<2 wt %), and the different types and strengths of adsorption to be classified with respect to the temperature of elimination.

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“…Interlayer distances were calculated as explained in refs. 27, 64, that is, as the d spacing minus the layer thickness (4.8 Å).…”

Section: Resultsmentioning

confidence: 99%

Structural Characterisation of Complex Layered Double Hydroxides and TGA‐GC‐MS Study on Thermal Response and Carbonate Contamination in Nitrate‐ and Organic‐Exchanged Hydrotalcites

Conterosito

Palin

Antonioli

et al. 2015

Chemistry A European J

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“…25,32 PAMAM dendrimers are ideal building blocks for a wide range of composite materials; therefore, their interaction with nanomaterials was extensively studied. 33 Accordingly, intercalation in layered clays, 34 their association with other macromolecules to form interpolyelectrolyte complexes, 35 and their ability to stabilize transition metal nanoclusters 36 have been reported. Adsorption experiments were also carried out on silica, 37,38 graphite, 39 and gold 40 surfaces using reflectometry, atomic force microscopy (AFM), and quartz crystal microbalance, respectively.…”

Section: ■ Introductionmentioning

confidence: 99%

Dendrimer-Stabilized Titanate Nanowire Dispersions as Potential Nanocarriers

et al. 2015

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The effect of poly(amido amine) (PAMAM) dendrimers of generations G2, G6, and G10 on the dispersion stability of titanate nanowires (TiONWs) as potential nanocarriers was clarified in order to develop biocompatible delivery systems. The PAMAMs adsorbed strongly on the oppositely charged TiONWs even under slightly alkaline conditions where the macromolecules possess low amounts of charged groups and they were able to reverse the charge of the particles. This process resulted in unstable dispersions near the dose where the charge reversal occurred, while stable samples were observed away from it. No generation dependence was found on the aggregation and charging behavior at low ionic strengths. Although heterogeneous adsorption of the dendrimers led to attractive patch-charge interactions at intermediate doses, interparticle forces of electrostatic origin described by Derjaguin and Landau, Verwey, and Overbeek (DLVO) played the major role in colloidal stability. The nanowires were found to adopt a face-to-face orientation within the aggregates, giving rise to the formation of well-defined bundles. Highly stable dispersions were observed once the TiONWs were coated with PAMAM dendrimers of higher generations even at elevated ionic strengths.

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Dendrimers Inside Materials

Laurent

Caminade

2011

Dendrimers

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Dendrimer intercalation in layered double hydroxides

Cited by 11 publications

References 25 publications

Structural Characterisation of Complex Layered Double Hydroxides and TGA‐GC‐MS Study on Thermal Response and Carbonate Contamination in Nitrate‐ and Organic‐Exchanged Hydrotalcites

Structural Characterisation of Complex Layered Double Hydroxides and TGA‐GC‐MS Study on Thermal Response and Carbonate Contamination in Nitrate‐ and Organic‐Exchanged Hydrotalcites

Dendrimer-Stabilized Titanate Nanowire Dispersions as Potential Nanocarriers

Dendrimers Inside Materials

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