Advances in Voltammetric Sensors Using Combinations of Phthalocyanines with Nanoparticles and/or Biomolecules in LB and LbL Films

Electrochemical sensors have been prepared using a range of materials and using a variety of methods.  The selection of phthalocyanines or nanoparticles as sensing materials in electrochemical sensors was inspired in their electrocatalytic properties¹.  In turn, nanostructured sensors prepared using the Langmuir-Blodgett (LB) or the electrostatic Layer-by-Layer (LbL) techniques have the advantage of the enhanced number of active sites that has a reflect in the increase in the intensity. The control of molecular architectures afforded by these techniques can led to the development of a variety of devices where synergy is achieved by combining distinct materials, including organic-inorganic hybrids².

In this work combinations of phthalocyanines with nanoparticles and/or biomolecules  in LB and LbL films have been developed and their structures have been analyzed. The films have been used as voltammetric sensors for the detection of compounds of interest in the food industry (i.e. phenols or organic acids). The role of the molecular interactions in the electrocatalytic properties or as biomimetic systems to immobilize biomolecules has been studied and the existence of synergistic effects has been evidenced. For instance, the combination of phthalocyanines with gold nanoparticles in LB films produced an increase in the sensitivity towards phenols  and detection limits of 10^-7 mol.L^-1 were attained. Similar detection limits could be obtained by combining phthalocyanines with silver nanoparticles in LbL films. LB and LbL films combining phthalocyanines and amphiphilic molecules provided biomimetic environments where enzymes could preserve their functionality. Detection limits as low as 10^-8 mol.L^-1 towards phenols were attained.

References:

¹M.L. Rodríguez-Méndez,  C. Medina, J.A. de Saja, C. Apetrei, R. Muñoz sensor arrays based on phthalocyanines: new developments on nanostructured and biomimetic electrochemical sensors. In Multisensor systems for chemical analysis: materials and sensors. Eds. L. Lvova, D. Kirsanov, C. Di Natale, and A. Legin. PAN STANFORD PUBLISHING. Chapter 4, 70-109 (2012)

²F. J. Pavinatto, E. G. R. Fernandez, P. Alessio J..C. Constantino,  J. A. de Saja, V. Zucolotto^,d O. N. Oliveira Jr. C. Apetrei, M. L. Rodriguez-MendezOptimized architecture for Tyrosinase-containing Langmuir-Blodgett films to detect pyrogallol J. Materials Chemistry 21, 4995-5003 2011

Figure 1: LB film formed by phthalocyanins/amphiphiles and nanoparticles