Layer-by-Layer Films Containing Peptides of the Cry1Ab16 Toxin from Bacillus thuringiensis for Nanodevices Development

PLACIDO ALEXANDRA; OLIVEIRA FARIAS EMANUEL A.; MARANI MARIELA M.; VASCONCELOS ADREANNE G.; MAFUD ANA C.; MASCARENHAS YVONNE P.; EIRAS CARLA; LEITE JOSÉ R. S. A.; DELERUE-MATOS MARÍA C.

Braga

Conferencia; 2016 NanoPortugal International Conference; 2016

Phantoms foundation, INL International Iberian Nanotechnology Laboratory

Amongthin film production techniques, layer-by-layer (LbL) self-assembly stands outbecause of its versatility, which has enabled applications in the fields ofbiomaterials, biosensors, drug/gene delivery, tissue engineering, implantablematerials, diagnostics, electronics, energy, and optics [1]. Peptidesare potential candidates to meet the needs of the modern world in relation todiagnosis, disease monitoring, quality control in industry, and more recently,detection of genetically modified organisms (GMOs) and food safety through thedevelopment of biosensors [2]. Cry1Ab16 is a toxin of crystalline insecticidal proteins that has beenwidely used in GMOs to gain resistance to pests. For the first time, in thisstudy, peptides derived from the immunogenic Cry1Ab16 toxin were immobilized asLbL films. Given the concern about food and environmental safety, a peptidewith immunogenic potential, PcL342-354C, was selected for characterization of itselectrochemical, optical, and morphological properties. The results obtained bycyclic voltammetry (CV) showed that the peptide have an irreversible oxidationprocess in electrolyte of 0.1 mol L-1 potassium phosphate buffer(PBS) at pH 7.2. It was also observed that the electrochemical response of thepeptide is governed mainly by charge transfer. In an attempt to maximize theelectrochemical signal of peptide, it was intercalated with natural (agar,alginate and chitosan) or synthetic polymers (polyethylenimine (PEI) andPoly(sodium 4-styrenesulfonate) (PSS)). The presence of synthetic polymers onthe film increased the electrochemical signal of PcL342-354C up to 100 times.Images by Atomic Force Microscopy showed that the immobilized PcL342-354Cformed self-assembled nanofibers with diameters ranging from 100 to 200 nm onthe polymeric film (Fig. 1). By UV-Visible spectroscopy (UV-Vis) it wasobserved that the ITO/PEI/PSS/PcL342-354C film grows linearly up to the fifthlayer, thereafter tending to saturation. X-ray diffraction confirmed thepresence on the films of crystalline ITO and amorphous polypeptide phases. Ingeneral, the ITO/PEI/PSS/PcL342-354C film characterization proved that thissystem is an excellent candidate for applications in electrochemical sensorsand other biotechnological applications for GMOs and environmental indicators.