Aqueous Solubilization of Hydrophobic Supramolecular Metal-Organic Nanocapsules

Published

June 1, 2014

Author(s)

Harshita Kumari, Steven R. Kline, Jerry L. Atwood

Abstract

Micelles of metal-seamed C-alkylpyrogallol[4]arene-based (PgC_nM) hexamers and dimers in water have been formulated and characterized using in situ scattering techniques. The aqueous solubilization of these hydrophobic nanocapsules is facilitated by the use of non-ionic surfactants, namely polysorbitans and sorbitans. The hydrophilic surfactants, tween 20, tween 40 and tween 80 are utilized to solubilize PgC₃Cu and PgC₃Ni hexamers, PgC₃Zn, PgC₃Co and PgC₃Ni dimers in water. The dimensions of micelles of tweens PgC₃Zn dimers and tweens PgC_{3Ni/ PgC}d3^Co dimers are studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The solubilization of more hydrophobic tweens PgC_cNi/Cu hexamers is aided via co-surfactants and the micelles thus formed are studied on both DLS (hydrodynamic radius/R_HS). SANS data is fitted to a polydisperse core-shell sphere model (R_HS) and used to calculate the radius of gyration (R_g). An increase in radius of the tween 20 (C12) and tween 40 (C16) based micelles is observed with an increase in the radius of the nanocapsule (dimer vs. hexamer); however, given the longer alkyl tails of tween 80(C18:1, cis 9), a remarkable progression in radius is not observed for tween 80-enclosed micelles due to the unsaturation (C9) and bent alkyl tail of the surfactant. The R_h : R_g ratios are close to 0.77 value for the control (0.62), tween 20 dimeric (0.67) and tween 20 hexameric (0.68) micelles that demonstrates the sphericity of micelles in water. In contrast, the higher R_H/R_g ration (0.76 to 0.93) of tween 80 based micelles is indicative of less compact species in aqueous solution.

Citation

Chemical Science

Volume

5

Pub Type

Journals

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Keywords

small angle neutron scattering, metal-organic nano capsules, self-assembly, Tween, solubilization

Citation

Kumari, H. , Kline, S. and Atwood, J. (2014), Aqueous Solubilization of Hydrophobic Supramolecular Metal-Organic Nanocapsules, Chemical Science, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=914115 (Accessed April 28, 2024)