Detection of catechol using mixed Langmuir-Blodgett films of a phospholipid and phthalocyanines as voltammetric sensors.
The combination of metallic phthalocyanines (MPcs) and biomolecules has been explored in the literature either as mimetic systems to investigate molecular interactions or as supporting layers to immobilize biomolecules. Here, Langmuir-Blodgett (LB) films containing the phospholipid dimyristoyl phosphatidic acid (DMPA) mixed either with iron phthalocyanine (FePc) or with lutetium bisphthalocyanine (LuPc(2)) were applied as ITO modified-electrodes in the detection of catechol using cyclic voltammetry. The mixed Langmuir films of FePc + DMPA and LuPc(2) + DMPA displayed surface-pressure isotherms with no evidence of molecular-level interactions. The Fourier Transform Infrared (FTIR) spectra of the multilayer LB films confirmed the lack of interaction between the components. The DMPA and the FePc molecules were found to be oriented perpendicularly to the substrate, while LuPc(2) molecules were randomly organized. The phospholipid matrix induced a remarkable electrocatalytic effect on the phthalocyanines; as a result the mixed LB films deposited on ITO could be used to detect catechol with detection limits of 4.30 × 10(-7) and 3.34 × 10(-7) M for FePc + DMPA and LuPc(2) + DMPA, respectively. Results from kinetics experiments revealed that ion diffusion dominated the response of the modified electrodes. The sensitivity was comparable to that of other non-enzymatic sensors, which is sufficient to detect catechol in the food industry. The higher stability of the electrochemical response of the LB films and the ability to control the molecular architecture are promising for further studies with incorporation of biomolecules.
Alessio
Priscila
P
Faculdade de Ciências e Tecnologia, Unesp Univ Estadual Paulista, 19060-900 Presidente Prudente, SP, Brazil.
Pavinatto
Felippe J
FJ
Oliveira
Osvaldo N
ON
De Saja Saez
Jose Antonio
JA
Constantino
Carlos J L
CJ
Rodríguez-Méndez
Maria Luz
ML
D002396:Catechols / Q000032:analysis*; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D005296:Ferrous Compounds / Q000737:chemistry*; D020404:Glycerophospholipids / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D007700:Kinetics; D017550:Spectroscopy, Fourier Transform Infrared
D002396:Catechols; D005296:Ferrous Compounds; D020404:Glycerophospholipids; D007211:Indoles; C493990:iron phthalocyanine; C025602:dimyristoylphosphatidic acid; C034221:catechol