GOx LbL Based Film Growth over Porous Alumina (PA) Followed by Diffuse Reflectance Spectroscopy
- PDF / 720,970 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 55 Downloads / 175 Views
GOx LbL Based Film Growth over Porous Alumina (PA) Followed by Diffuse Reflectance Spectroscopy Letícia M. M. Ferro1, Marystela Ferreira1 and Francisco Trivinho-Strixino1 1
Federal University of São Carlos, Department of Physics, Chemistry and Mathematics, UFSCar,
Campus of Sorocaba, Sorocaba 18052-780, SP, Brazil. ABSTRACT In this study, the growth of LbL film of polyallylamine hydrochloride (PAH), polyvinyl sulfonic acid (PVS) and glucose oxidase (GOx) in porous anodic alumina substrate (PAA) was accompanied by total reflectance technique. The PAA substrate was synthesized with aluminum anodisation and sample morphology was characterized by scanning electron microscopy (SEM). INTRODUCTION The aluminum undergoes an oxidation reaction when exposed directly to oxygen of air leading to the formation of a thin oxide layer (thickness in the order of ~2 nm). This oxidation process on the metal surface can also occur by the passage of electricity when using aluminum as an anode in an appropriate electrolytic solution. This oxidation process results in a oxide porous film, called porous anodic alumina (PAA), which has well organized pore geometry depending on the anodising conditions such as the anodisation duration, the electrolyte temperature and composition and, finally, the applied voltage or current [1, 2]. Several investigations have been performed using PAA film as a substrate for growth of self-assembled films. The reasons why it stands out are their high quality optical responses when submitted to reflectance and luminescence techniques and also the possibility of control the pore geometry with simple experimental setup. Altering anodising parameters, it is possible to change the length and the diameter of pores, which is interesting when manufacturing sensors devices giving to then a high surface area and good sensing capability [3]. Ultrathin films have been investigated by presenting various applications such as electrochemical sensors and photoluminescent devices. The techniques used in the preparation of ultrathin films aimed to get organized structures and thickness with good properties at the molecular scale. One of the methods used in the manufacturing of thin films is the layer-by-layer technique (LbL) based on the electrostatic forces or covalent bonds of molecules in each layer and which is widely used because of the simple apparatus setup required [4-10]. The preparation process of self-assembled films was based on the ideas of Iler et al. [8] in 1966, who worked with alternating adsorption of oppositely charged colloidal particles. Another important research to improve the LbL technique was of Savig et al. [8] in the 80's, who described the formation of multilayer systems from bifunctional molecules, demonstrating the possibility of obtaining films consisting of chemically adsorbed monolayers by covalent bonds [8, 11]. In the 90s, Decher et al. [8] proposed a self-assembly technique based on electrostatic interactions with amphiphilic compounds or polyelectrolytes. During the self-assembly, a
char
Data Loading...
