title: Silk fibroin organization induced by chitosan in layer-by-layer films: Application as a matrix in a biosensor.
abstract: In this paper, we show that chitosan may induce conformation changes in silk fibroin (SF) in layer-by-layer (LbL) films, which were used as matrix for immobilization of the enzyme phytase to detect phytic acid. Three chitosan (CH) samples possessing distinct molecular weights were used to build CH/SF LbL films, and a larger change in conformation from random coils to β-sheets for SF was observed for high molecular weight chitosan (CHH). The CHH/SF LbL films deposited onto interdigitated gold electrodes were coated with a layer of phytase, with which phytic acid could be detected down to 10-9M using impedance spectroscopy as the principle of detection and treating the data with a multidimensional projection technique. This high sensitivity may be ascribed to the suitability of the CHH/SF matrix, thus indicating that the molecular-level interactions between chitosan and SF may be exploited in other biosensors and biodevices.
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), CP 369, 13560-970, São Carlos, SP, Brazil. Electronic address: delezuk@gmail.com.
authors.forename: Jorge A M
authors.initials: JA
authors.lastname: Delezuk
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), CP 369, 13560-970, São Carlos, SP, Brazil.
authors.forename: Adriana
authors.initials: A
authors.lastname: Pavinatto
authors.affiliation: Institute of Science and Technology at the Federal University of São Paulo (UNIFESP), 330 Talim Street, São José dos Campos, SP, Brazil.
authors.forename: Marli L
authors.initials: ML
authors.lastname: Moraes
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), CP 369, 13560-970, São Carlos, SP, Brazil.
authors.forename: Flávio M
authors.initials: FM
authors.lastname: Shimizu
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), CP 369, 13560-970, São Carlos, SP, Brazil.
authors.forename: Valquíria C
authors.initials: VC
authors.lastname: Rodrigues
authors.affiliation: São Carlos Institute of Chemistry, University of São Paulo (USP), CP 780, 135660-970, São Carlos, SP, Brazil.
authors.forename: Sérgio P
authors.initials: SP
authors.lastname: Campana-Filho
authors.affiliation: Institute of Chemistry, São Paulo State University (UNESP), CP 355, 14801-970, Araraquara, SP, Brazil.
authors.forename: Sidney J L
authors.initials: SJ
authors.lastname: Ribeiro
authors.affiliation: São Carlos Institute of Physics, University of São Paulo (USP), CP 369, 13560-970, São Carlos, SP, Brazil.
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
mesh_terms: D015374:Biosensing Techniques; D048271:Chitosan / Q000737:chemistry*; D004566:Electrodes; D005349:Fibroins / Q000737:chemistry*; D006046:Gold
chemical_list: D006046:Gold; D005349:Fibroins; D048271:Chitosan
keywords: Biosensor; Chitosan; Layer-by-layer; Silk fibroin