Enzyme and Microbial Technology 52 (2013) 141–150 Contents lists available at SciVerse ScienceDirect Enzyme and Microbial Technology jou rn al h om epage: www.elsevier.com/locate/emt Protic ionic liquid as additive on lipase immobilization using silica sol–gel Ranyere Lucena de Souza a , Emanuelle Lima Pache de Faria a , Renan Tavares Figueiredo a , Lisiane dos Santos Freitas b , Miguel Iglesias c , Silvana Mattedi c , Gisella Maria Zanin d , Onélia Aparecida Andreo dos Santos d , João A.P. Coutinho e , Álvaro Silva Lima a , Cleide Mara Faria Soares a,∗ a UNIT, Universidade Tiradentes, Instituto de Tecnologia e Pesquisa-ITP, Av. Murilo Dantas, 300, Prédio do ITP, Farolândia, Aracaju, SE, Brazil b UFS, Universidade Federal de Sergipe, Departamento de Engenharia Química, Avenida Marechal Rondon, São Cristovão, SE, Brazil c UFBA – Universidade Ferderal da Bahia, Departamento de Engenharia Química, Rua Aristides Novis 2, Federac ¸ ão, Salvador, BA, Brazil d UEM, Universidade Estadual de Maringá, Av. Colombo, 5790-zona 7, Maringá, PR, Brazil e CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal a r t i c l e i n f o Article history: Received 16 July 2012 Received in revised form 16 December 2012 Accepted 17 December 2012 Keywords: Lipase Immobilization Sol–gel Protic ionic liquids a b s t r a c t Ionic liquids (ILs) have evolved as a new type of non-aqueous solvents for biocatalysis, mainly due to their unique and tunable physical properties. A number of recent review papers have described a variety of enzymatic reactions conducted in IL solutions, on the other hand, to improve the enzyme’s activity and stability in ILs; major methods being explored include the enzyme immobilization (on solid sup- port, sol–gel, etc.), protic ionic liquids used as an additive process. The immobilization of the lipase from Burkholderia cepacia by the sol–gel technique using protic ionic liquids (PIL) as additives to protect against inactivation of the lipase due to release of alcohol and shrinkage of the gel during the sol–gel process was investigated in this study. The influence of various factors such as the length of the alkyl chain of protic ionic liquids (monoethanolamine-based) and a concentration range between 0.5 and 3.0% (w/v) were evaluated. The resulting hydrophobic matrices and immobilized lipases were characterised with regard to specific surface area, adsorption–desorption isotherms, pore volume (V p ) and size (d p ) according to nitrogen adsorption and scanning electron microscopy (SEM), physico-chemical properties (thermogravimetric – TG, differential scanning calorimetry – DSC and Fourier transform infrared spec- troscopy – FTIR) and the potential for ethyl ester and emulsifier production. The total activity yields (Y a ) for matrices of immobilized lipase employing protic ionic liquids as additives always resulted in higher values compared with the sample absent the protic ionic liquids, which represents 35-fold increase in recovery of enzymatic activity using the more hydrophobic protic ionic liquids. Compared with arrays of the immobilized biocatalyst without additive, in general, the immobilized biocatalyst in the presence of protic ionic liquids showed increased values of surface area (143–245 m 2 g -1 ) and pore size (19–38 ˚ A). Immobilization with protic ionic liquids also favoured reduced mass loss according to TG curves (always less than 42.9%) when compared to the immobilized matrix without protic ionic liquids (45.1%), except for the sample containing 3.0% protic ionic liquids (46.5%), verified by thermogravimetric analysis. Ionic liquids containing a more hydrophobic alkyl group in the cationic moiety were beneficial for recovery of the activity of the immobilized lipase. The physico-chemical characterization confirmed the presence of the enzyme and its immobilized derivatives obtained in this study by identifying the presence of amino groups, and profiling enthalpy changes of mass loss. © 2013 Elsevier Inc. All rights reserved. 1. Introduction Lipase (EC 3.1.1.3) is an important enzyme with a wide vari- ety of applications in the food, fine chemical and pharmaceutical industries due to the multiplicity of reactions it catalyses, such ∗ Corresponding author. Tel.: +55 79 91322592; fax: +55 7932182190. E-mail addresses: cleide.soares@pq.cnpq.br, cleide18@yahoo.com.br (C.M.F. Soares). as esterification, transesterification and hydrolysis [1–5]. Among them, the lipase from Burkholderia cepacia is distinguished by its ability to carry out organic synthesis, a feature of great inter- est to industry [6]. The economy of biocatalytic processes can be improved by improving the reuse and/or the enzyme itself, may improve performance of the enzyme under optimal condi- tions of reaction process (e.g., temperatures of alkalinity, acidity, organic solvents, and high), a requirement that has often retarded enzyme application in industrial chemical synthesis [7,8]. There- fore, numerous efforts have focused on the preparation of lipases 0141-0229/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.enzmictec.2012.12.007