Experimental and DFT Characterization of Halloysite Nanotubes Loaded with Salicylic Acid

Year: 2016

Authors: Spepi A., Duce D., Pedone A., Presti D., Gonzalez Rivera J., Ierardi V., Tiné M.R.

Autors Affiliation: Chemistry and Industrial Chemistry Department, University of Pisa, Via G. Moruzzi 13, I-56124 Pisa, Italy

Department of Chemical and Geological Sciences, University of Modena and Reggio-Emilia, via G. Campi 103, I-41125 Modena,

Nanomed Laboratories Physics Department, University of Genova, Largo R. Benzi 10, 16132, Genova, Italy

Abstract: Halloysite nanotubes (HNTs) and salicylic acid (SA) are natural substances widely used in different fields. HNTs are very promising as nanocarriers because of their biocompatibility, atoxicity, anti-inflammatory properties and capacity to maintain the biological activity of immobilized enzymes. Because of its bactericidal and antiseptic properties, salicylic acid (SA) is used in pharmaceutical formulations, and as an additive for preserving foods and cosmetics. In this study, we set up a procedure for the loading of HNTs with SA for their possible application in active food packaging. Pristine HNTs were studied together with acidic etched HNTs with enlarged internal lumen, and various pH values for the loading solutions were tested in order to obtain the maximum loading. The HNTs-empty and loaded with SA-were characterized by TG-FTIR, FTIR SEM, STEM, and nitrogen adsorption/desorption isotherms measurements. We obtained a maximum loading of 10.5% (w/w), using HNTs pretreated with H2SO4 2 M at 25 degrees C for 48h and a solution of sodium salicylate at pH 8. We also characterized the interaction of SA-HNTs at a molecular level by combining ATR-FTIR measurements and periodic density functional theory (DFT) calculations. We believe that the information on the SA-HNT complexes derived from our research should help to improve the current knowledge of SA clay interactions. In addition, it should be of interest for environmental and earth sciences since SA is used to model natural organic matter (NOM) in both experimental and theoretical studies of NOM adsorption on different kinds of mineral surfaces.


Volume: 120 (47)      Pages from: 26759  to: 26769

KeyWords: Halloysite nanotubes, mesopores materials, salicylic acid, drug delivery
DOI: 10.1021/acs.jpcc.6b06964

Citations: 29
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