Photoinitiator and anesthetic incorporation into mesoporous silica Laredo S. e Oliveira a , Liziane Marçal a , Lucas A. Rocha a , Emerson H. de Faria a , Katia J. Ciuffi a , Eduardo J. Nassar a, ⁎, Ivo C. Corrêa b a Universidade de Franca, Av. Dr. Armando Salles Oliveira, 201, - Franca/SP, CEP 14404-600, Brazil b Universidade Federal do Rio de Janeiro, Brazil abstract article info Article history: Received 28 November 2016 Received in revised form 30 September 2017 Accepted 11 December 2017 Available online 19 December 2017 The sol–gel methodology affords mesoporous silica with controlled pore size. The resulting materials can be used to incorporate, immobilize, or encapsulate several molecules for further application as drug delivery systems, an- tibacterials, and photonic devices, just to mention a few examples. Dental resins employed in tooth repair consist of an organic matrix, a charged inorganic component, and union agents; a photoinitiator triggers resin polymer- ization. In this work, we incorporated the photoinitiator camphorquinone or the anesthetic ethyl 4- aminobenzoate into mesoporous silica. Characterization of the materials by infrared and electronic spectroscopy, thermal analysis, X-ray diffraction, and specific surface area confirmed the presence of the photoinitiator or the anesthetic in the silica matrix. Kinetic and equilibrium assays as well as absorption studies showed that the meso- porous silica obtained here can be applied as a drug delivery system. © 2017 Elsevier B.V. All rights reserved. Keywords: Sol-gel Camphorquinone Ethyl 4-aminebenzoate Resin composite 1. Introduction Over the last 30 years, the physical, mechanical, and esthetic proper- ties of composite resins have led to their wide application in routine dental restoration [1,2]. Composite resins are a classic example of hybrid materials composed of an organic matrix and inorganic particles [3,4]. The combination of organic and inorganic components produces new properties: the inorganic particles provide the hybrid with rigidity and thermal stability, whereas the organic polymer yields a flexible compos- ite resin that can be easily processed. Camphorquinone is used as a visible-light photoinitiator for medical applications; it can convert a monomer into polymer networks [5,6]. Dentists commonly use camphorquinone during dental restoration [7]. The local anesthetic ethyl 4-aminebenzoate, or benzocaine, a para-aminobenzoic acid ethyl ester, was the first synthetic agent to be used in clinical practice [8]. The discovery of molecular sieves by Mobil Corporation has prompted extensive investigation into hybrid materials [9,10]. The sol–gel methodology has been the preferred process to obtain mesopo- rous silica [11,12]. Surfactants have served as molding agents, to afford silica materials with different pore sizes [13–15]. Indeed, mesoporous silica prepared by the sol–gel methodology in the presence of a surfactant as pore template presents an organized structure that pro- motes new physical and chemical properties. These materials can inter- act with ions and/or molecules incorporated into the silica pores or immobilized onto the silica surface, which paves the way for their appli- cation in different areas, such as catalysis and sensor devices [10,16]. Silica nanoparticles are another important matrix into which several kinds of molecules, like antifungals [3], La(III) compounds, and chitosan [17,18], can be incorporated. Other matrixes, including alumina parti- cles [19], oxide nanoparticles [20], and halloysite nanotubes [21], have also been employed to synthesize composite materials. The literature contains many papers on the incorporation of phar- maceuticals and medications into mesoporous silica for controlled re- lease studies. The silica matrix MCM-41 SBA-15 is the most often investigated for incorporation of the anesthetic and anti-inflammatory agent ibuprofen [22], levofloxacin [23], indometacin, [24,25], and furo- semide [26]. Numerous other studies have been conducted on release systems involving mesoporous silica [27–32] and on technological ap- plications for this matrix [33–36], but none of the literature articles have used the systems proposed herein. Therefore, we aimed to explore the ability of mesoporous silica to act as a controlled released system for various compounds. To begin with, we used compounds that are com- monly applied in dental composite resins and incorporated either the photoinitiator camphorquinone or the local anesthetic ethyl 4- aminobenzoate into them. To synthesize the silica, we used the surfac- tant cetyltrimethylammonium bromide, which gave pores with ideal Powder Technology 326 (2018) 62–68 ⁎ Corresponding author at: Universidade de Franca, Av. Dr. Armando Salles Oliveira, 201, CP 82 - CEP: 14404–600, Franca, SP, – Brazil. E-mail address: eduardo.nassar@unifran.edu.br (E.J. Nassar). https://doi.org/10.1016/j.powtec.2017.12.044 0032-5910/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Powder Technology journal homepage: www.elsevier.com/locate/powtec