ORIGINAL PAPER Electrogeneration of polyluminol and chemiluminescence for new disposable reagentless optical sensors Audrey Sassolas & Loïc J. Blum & Béatrice D. Leca-Bouvier Received: 27 June 2007 / Revised: 24 October 2007 / Accepted: 31 October 2007 / Published online: 2 December 2007 # Springer-Verlag 2007 Abstract A performant reagentless electrochemiluminescent (ECL) detection system for H 2 O 2 is presented, based on an electropolymerized polyluminol film prepared under near- neutral conditions. Such an original polyluminol electrodepo- sition is reported for the first time and on a screen-printed electrode (SPE) surface. Electropolymerized luminol acts as an active luminophore of the electrochemiluminescent reaction, as the monomer does. Polymerization conditions have been optimized in order to obtain the best ECL responses to H 2 O 2 . By performing electrodeposition in a potentiostatic mode, at 425 mV vs. Ag|AgCl, in 0.1 mol L -1 phosphate/0.1 mol L -1 KCl pH 6 and 1 mmol L -1 luminol, with a total charge of 0.5 mC, the linear range for H 2 O 2 detection extends from 7.9×10 -8 mol L -1 to 1.3×10 -3 mol L -1 . Such performant disposable reagentless easy-to-use miniaturized systems based on SPEs should be applicable to the electrochemilu- minescent detection of many oxidase-substrate compounds. Keywords Luminol . Electropolymerization . Electrochemiluminescence . Optical detection . Screen-printed electrode Introduction Electrogenerated chemiluminescence (ECL) of luminol is widely employed to develop very sensitive biosensors allowing the detection of analytes at low concentrations and over a wide range. Such optical systems are powerful in terms of sensitivity and interference insensitivity [1–9]. Chemilu- minescence reactions which have been reported are generally based on conventional luminophore addition to solution [2– 10] but also on immobilized reagents, mainly based on electrostatic interactions [11–14]. Luminol can be regarded as an aniline monomer derivative (Scheme 1) whose electrochemical immobilization represents an original way of designing promising reagentless sensors. Polyluminol refers to the so-called polymer obtained from luminol electropolymerization. Its electrogenerated formation has been mainly reported by cyclic voltammetry in an H 2 SO 4 acidic medium [15–20]. Electropolymerization is known as an attractive method for enzyme entrapment [21, 22]. Films can be prepared easily in a rapid one-step procedure and the method enables exact control of the thickness of the polymer layer. It is based on the measurement of either the electric charge passed during potentiostatically or galvanostatically con- trolled electrochemical polymerization or the number of potential cycles performed during potentiodynamically controlled electrochemical polymerization. Zhang and Chen [15] first demonstrated that luminol, like aniline [23–25], can be electrochemically polymerized in an acidic solution, under potentiodynamic or potentiostatic conditions. Luminol electropolymerization can thus be con- sidered as a technique of luminophore immobilization. It has been reported that luminol polymerization performed in acidic media involves the amino group, the polymeric structure being generated from para coupling of monomer molecules [15] (Scheme 2). The –NH 2 group is not involved in the electrochemilu- minescent reaction of luminol [26] (Scheme 3), so polyluminol, as its monomer counterpart, can act as an electrochemiluminescent luminophore. Anal Bioanal Chem (2008) 390:865–871 DOI 10.1007/s00216-007-1731-z A. Sassolas : L. J. Blum : B. D. Leca-Bouvier (*) Université de Lyon, Université Lyon 1, CNRS, UMR5246, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Laboratoire de Génie Enzymatique et Biomoléculaire, F-69622, Villeurbanne Cedex, France e-mail: leca@univ-lyon1.fr