Eumelanin Coating of Silica Aerogel by Supercritical Carbon Dioxide Deposition of a 5,6-Dihydroxyindole Thin Film

Giuseppe Caputo; Irene Bonadies; Ludovico Migliaccio; Maria Federica Caso; Alessandro Pezzella

doi:10.3390/ma11091494

Eumelanin Coating of Silica Aerogel by Supercritical Carbon Dioxide Deposition of a 5,6-Dihydroxyindole Thin Film

Materials (Basel). 2018 Aug 21;11(9):1494. doi: 10.3390/ma11091494.

Authors

Giuseppe Caputo¹, Irene Bonadies², Ludovico Migliaccio³, Maria Federica Caso⁴, Alessandro Pezzella^{5

6}

Affiliations

¹ Dipartimento Dell'Innovazione Industriale e Digitale-Ingegneria Chimica, Gestionale, Meccanica e Informatica, Università di Palermo, 90133 Palermo, Italy. giuseppe.caputo01@unipa.it.
² Institute for Polymers, Composites and Biomaterials (IPCB), CNR, Via Campi Flegrei 34, I-80078 Pozzuoli (Na), Italy. irene.bonadies@ipcb.cnr.it.
³ Department of Chemical Sciences, University of Naples "Federico II" Via Cintia 4, I-80126 Naples, Italy. ludovico.migliaccio@unina.it.
⁴ Nanofaber Spin-Off at Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Casaccia Research Centre, Via Anguillarese 301, 00123 Rome, Italy. maria.federica.caso@gmail.com.
⁵ Institute for Polymers, Composites and Biomaterials (IPCB), CNR, Via Campi Flegrei 34, I-80078 Pozzuoli (Na), Italy. alessandro.pezzella@unina.it.
⁶ Department of Chemical Sciences, University of Naples "Federico II" Via Cintia 4, I-80126 Naples, Italy. alessandro.pezzella@unina.it.

Abstract

Eumelanin integration in silica aerogel (SA) was achieved via supercritical adsorption of 5,6-dyhydroxyindole (DHI) from CO₂. Notably, after the supercritical treatment, DHI evolved towards spontaneous polymerization, which resulted in uniform pigment development over the SA. The new material was characterized for its morphological and physicochemical properties, disclosing the formation of a eumelanin-like coating, as confirmed by UV⁻vis and electron paramagnetic resonance (EPR) spectroscopy.

Keywords: eumelanins; silica aerogel; supercritical CO2.