Immobilization of DNA at glassy carbon electrodes for the development of affinity biosensors

M. L. PEDANO; G. A. RIVAS

BIOSENSORS & BIOELECTRONICS

ELSEVIER ADVANCED TECHNOLOGY

Año: 2003 vol. 18 p. 269 - 277

0956-5663

The adsorption and electrooxidation of nucleic acids on glassy carbon electrodes are evaluated by using chronopotentiometric stripping analysis. The influence of electrochemical pretreatments, supporting electrolyte, halides and monovalent cations levels as well as the role of the oligonucleotide length and composition, accumulation potential and time on the adsorption and further electrooxidation of oligo(dG)11 and oligo(dG)21 are discussed. The adsorption behavior of single and double stranded calf thymus DNA on untreated glassy carbon electrodes is also evaluated. Trace (mg/l) levels of the oligonucle tides and polynucleotides can be readily detected following short accumulation periods with detection limits of 25, 60, 126 and 219 mg/l for oligo(dG)21, oligo(dG)11, ss and ds calf thymus DNA, respectively. The confined DNA layers demonstrated to be stable in air, in 0.200 M acetate buffer pH 5.00 and in 0.020 M phosphate buffer pH 7.40/0.50 M NaCl.