1. 5. Thereafter 10-bilayers of PEI/GOx LbL film were produced followed by photoluminescence emission spectrums. PEI/GOx LbL film growth over Porous Alumina (PA) followed by fluorescence spectroscopy Letícia F. Mendes; Marystela Ferreira and Francisco Trivinho-Strixino* Campus de Sorocaba – Rod. João Leme dos Santos (SP-264), Km 110, Bairro do Itinga – Sorocaba – SP – Brazil – CEP: 18052-780 Universidade Federal de São Carlos Department of Physics, Chemistry and Mathematics AFM images of the PA samples before and after PEI/GOx LbL film growth CONCLUSION Acknowledgments: Porous Alumina (PA) has attracted great attention due to their chemical and optical properties which are responsible to several applications in sensitive platforms. In order to extend these applications, several studies have also being carried out trying to improve the PA films surface modification with ultrathin films composed of different materials that can be aimed to provide biological selectivity. Furthermore ultrathin films can be easily obtained from the Layer-by-Layer (LbL) technique. As observed, the GOx enzyme behavior over Porous Alumina (PA) film was more intensely noticed using the fluorescence spectroscopy technique where the effects of the GOx casting film deposition provided in electropolished and anodized aluminum samples were different. Therefore, using fluorescence spectroscopy it was possible to follow the growth kinetics of self- assembled LbL PEI/GOx films over Porous Alumina (PA), which presents a linear increase when accompanied by the photoluminescence emission at 442 nm, indicating effective deposition of each bilayers over the PA substrate. In addition, important processes was observed in these films concerning to their optical properties, as the internal transfer of energy between the GOx and the PA substrate when it was excited at 280 nm (GOx exciting wavelength) beyond the interference fringes related to the Fabry- Pérot cavity, a fact that would allow the use of this device for the construction of an optical biosensor for glucose. Casting GOx film over different substrates and the optical characterization Figure 1. Reflectance A) and B) Photoluminescence emission spectra of casting GOx over different substrates. Excited wavelength 280 nm. Grant 2010/10813-0 Grant 2012/01997-6 PEI/GOx LbL film growth over Porous Alumina (PA) Figure 3. AFM images of the PA samples A) and B) PEI/GOx 10-bilayers LbL film over PA. 1. Aluminum samples were mechanically polished using sand paper number 600 and 1200. 2. A cleaning procedure was performed using a mixture of deionized water and detergent followed by bath in acetone. 3. The electropolishing was carried out using in a mixture of perchloric acid and ethyl alcohol (1:3 v/v) under constant voltage of 15 V, at 0°C, for 180 s. 4. Mild anodization of the samples: Electrolyte - H 2 C 2 O 4 0,3 mol/L, Voltage – 40V Temperature- 20ºC (A)(B) Figure 2. PEI/GOx LbL film growth over Porous Alumina (PA) followed by Photoluminescence emission spectra at GOx exciting wavelength (280 nm). Inset: photoluminescence versus number of bilayers at 442 nm in triplicate. 1 st ANODIZATION: 7200 s Removal of the oxide H 3 PO 4 (0,4 M) / CrO 3 (0,2 M) at 60 ° C for 3600 s 2 sd ANODIZATION: 1800 s Chemical etching H 2 C 2 O 4 0,3 mol/L at 20 ° C for 1800 s INTRODUCTION EXPERIMENTAL PROCEDURE * fstrixino@ufscar.br Number of deposited bilayers Photoluminescence emission band intensity Characteristic fringes related to the Fabry-Pérot cavity in PA film PA Synthesis LbL film Synthesis Grant 443125/2014-7