Green Chemistry TUTORIAL REVIEW Cite this: Green Chem., 2015, 17, 1362 Received 13th November 2014, Accepted 1st December 2014 DOI: 10.1039/c4gc02221a www.rsc.org/greenchem Ultrasound enhanced laccase applications Idalina Gonçalves, Carla Silva† and Artur Cavaco-Paulo* Laccases (EC 1.10.3.2) are copper-containing enzymes that oxidize a variety of phenolics and other aro- matic compounds through a radical-catalyzed mechanism. The use of mediators acting as vehicles for electron transfer can expand the range of laccase substrates to other classes of chemical compounds. Ultrasound irradiation through a liquid medium generates reactive free radical species, promoting a local turbulence/liquid microcirculation and enhancing the mass transport process rates. Combined laccase and ultrasound processes lead to the reduction of the consumption of chemicals, energy and water, and these are presented as promising systems for reducing the environmental impact and the operational costs of conventional industrial processes. Introduction Laccases have been identified as a potential strategy for the development of a sustainable industry and for potentiating an ecological profile. Their application across various industrial sectors has allowed the reduction of operational costs, the development of entirely new products with concomitant quality enhancement, as well as the sustainability of environ- mental processing. Sonochemistry is a high-energy chemistry area that explores various chemical reactions and processes, allowing the reduction of the quantity of hazardous chemicals, the use of environmentally friendly solvents, the development of reaction conditions with increased selectivity, the reduction of energy consumption and the introduction of alternative or renewable feedstocks. 1 Both ultrasound and laccase processes have been shown to be promising eco-friendly alternatives to the standard chemical systems, leading to economically viable performances. The introduction of ultrasound in laccase reac- tions has rapidly attracted the attention of researchers, and Idalina Gonçalves Dr Idalina Gonçalves graduated in Biochemistry and Food Chem- istry (2008) at the University of Aveiro, Portugal. She completed her MSc in Textile Chemistry (2011) at the University of Minho, Portugal. Recently, she accomplished her PhD in Chemi- cal and Biological Engineering (2014) at the same university, with a thesis focused on the combined laccase–ultrasound processes for industrial appli- cations. Her scientific research involves the development of novel biomaterials with improved bio- logical properties across several areas of expertise, such as textiles, and biomedical and food engineering. Dr Carla Silva Dr Carla Silva graduated in Textile Engineering (2000) and completed her MSc degree in Fabrication Technology (2002) at the University of Minho, Portu- gal. She gained her PhD degree in Textile Chemistry (2008) with a thesis focused on the enzymatic treatment of polyamide 6.6 fibres, also at the University of Minho. Her research has been focused in the use of biotechno- logy for fibre modification, pro- teins for drug delivery and ultrasound for enzymatic processing. Nowadays, she is an auxili- ary researcher in 3B’s Research Group, a team at the interface of biomedical engineering and materials science, and is developing work in the glycomics field. † Presently at ICVS/3B’s Research Group, Biomaterials, Biodegradables and Bio- mimetics, University of Minho, Headquarters of the European Institute of Excel- lence on Tissue Engineering and Regenerative Medicine, AvePark, S. Cláudio de Barco, 4806-909 Taipas, Guimarães, Portugal. CEB – Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal. E-mail: artur@deb.uminho.pt 1362 | Green Chem. , 2015, 17, 1362–1374 This journal is © The Royal Society of Chemistry 2015