Pore size effect in the amount of immobilized enzyme for manufacturing carbon ceramic biosensor Elisangela Muncinelli Caldas a, b , Dhjulia Novatzky a , Monique Deon a , Eliana Weber de Menezes a , Plinho Francisco Hertz c , Tania Maria Haas Costa a , Leliz Ticona Arenas a , Edilson Valmir Benvenutti a, * a Instituto de Química, UFRGS, CP 15003, CEP 91501-970, Porto Alegre, RS, Brazil b Instituto Federal de Educaç~ ao, Ci^ encia e Tecnologia, CEP 95180-000, Farroupilha, RS, Brazil c Instituto de Ci^ encia e Tecnologia de Alimentos, UFRGS, CEP 91501-970, Porto Alegre, RS, Brazil article info Article history: Received 5 February 2017 Received in revised form 16 March 2017 Accepted 27 March 2017 Available online 30 March 2017 Keywords: Textural properties Interconnected pores Silica xerogel Cyclic voltammetry Chronoamperometry GOD enzyme abstract Understanding the mechanism of enzyme immobilization in porous designed matrices is important issue to develop biosensors with high performance. Mesoporous carbon ceramic materials with conductivity and appropriated textural characteristics are promising candidates in this area. In this work, carbon ceramic materials were synthesized using the sol-gel method by planning the experimental conditions to obtain materials with different pore size, from 7 to 21 nm of diameter. The study of the influence of pore size in the biomacromolecules immobilization capacity was performed using glucose oxidase enzyme as probe. The influence of textural characteristics of material in the amount of enzyme immobilized, as well as, its performance as biosensor, was studied. On the surface of highest pore size matrix, it was possible to immobilize the highest amount of enzyme, resulting in better electrochemical response. With this simple material, composed only by silica, graphite and enzyme, which was improved by the amount of immobilized enzyme through the enlargement of matrix pore size, it was possible to prepare an elec- trode to be applied as biosensor for glucose determination. This electrode presents good reproducibility, sensitivities of 0.33 and 4.44 mA mM 1 cm 2 and detection limits of 0.93 and 0.26 mmol L 1 , in argon and oxygen atmosphere, respectively. Additionally, it can be easily reused by simple polishing its surface. © 2017 Published by Elsevier Inc. 1. Introduction The interest in developing materials containing enzymes has been rising in the last decades because of the numerous applica- tions in enzymatic catalysis and in the preparation of biosensors [1e5]. These materials present high selectivity and specificity, minimized impurities, easier product separation and environ- mental acceptance, when compared with non-enzymatic systems [6]. An important aspect when enzymatic materials are being developed is the immobilization and stabilization of the bio- molecules on adequate substrates. Although the adsorption of en- zymes and proteins in solid matrices has been widely studied, the ability to control the amount adsorbed, the interaction between enzyme and matrix surface, and the location of the enzyme in the pore structure are still an important field to be investigated [7]. There are several reports dealing with the enzyme immobilization on porous materials, however the immobilization is commonly accompanied by drastic reduction in the textural characteristics such as surface area and pore volume. This behavior can be consequence of fully entered enzyme inside of pores or also due to immobilization on external surface leading to pore blocking [7]. For immobilization inside of pores, it should be taking into account also the remained free space into the pore to provide sufficient enzyme mobility and retain its catalytic activity. Additionally, the free space eases the substrate diffusion to the catalytic sites [8]. Therefore, to synthesize porous materials with adequate pore structure allowing the immobilization of enzyme, without the loss of textural prop- erties, is still a challenge [7,9]. Concerning electrochemical sensors, there is a recent interest in the preparation of devices based on carbon ceramic materials [10e12]. These materials are obtained by sol-gel synthesis method, based on hydrolysis and polycondensation of silicon precursor * Corresponding author. E-mail address: benvenutti@ufrgs.br (E.V. Benvenutti). Contents lists available at ScienceDirect Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso http://dx.doi.org/10.1016/j.micromeso.2017.03.051 1387-1811/© 2017 Published by Elsevier Inc. Microporous and Mesoporous Materials 247 (2017) 95e102