Electrochemical sensing of the behaviour of oligonucleotide lipoplexes at charged interfaces

TY - JOUR

T1 - Electrochemical sensing of the behaviour of oligonucleotide lipoplexes at charged interfaces

AU - Piedade, J. A.P.

AU - Mano, M.

AU - Pedroso De Lima, M. C.

AU - Oretskaya, T. S.

AU - Oliveira-Brett, A. M.

N1 - Funding Information: Financial support from Fundação para a Ciência e Tecnologia (FCT), Ph.D. Grants PRAXIS XXI/SFRH/BD/6134/2001 (JAPP) and PRAXIS XXI/SFRH/BD/4897/2001 (MM), POCTI (co-financed by the European Community Fund FEDER), ICEMS (Research Unit 103) and European Projects QLK3-2000-01311 and ERBICT15CT960804 are gratefully acknowledged.

PY - 2004/11/15

Y1 - 2004/11/15

N2 - Complexes between short oligodeoxynucleotides (ODN) with a variable dG xdCy base composition and liposomes composed of the cationic lipid DOTAP (ODN lipoplexes) were studied by differential pulse voltammetry at a glassy carbon electrode. Since lipoplexes are spontaneously formed by electrostatic interactions, the objective of the voltammetric study was to investigate their behaviour at the electrode surface/solution interface. It was verified that the peak current in the voltammograms for ODN lipoplexes was due to guanosine oxidation and that it was influenced both by the applied adsorption potential and the lipoplex (±) charge ratio used. It was found that for low ODN lipoplexes (±) charge ratios the peak current obtained was enhanced when compared to that registered with free ODN for the same concentration. This allowed a higher sensitivity in the determination of ODN by differential pulse voltammetry and a limit of detection of 5.5 ng/mL was achieved. A model that explains the organisation of ODN lipoplexes at the electrode surface/solution interface is proposed. The electrochemical results presented account for a better physicochemical characterisation of lipoplexes at charged interfaces, which can be important for the understanding and development of gene therapy vectors based on ODN lipoplexes.

AB - Complexes between short oligodeoxynucleotides (ODN) with a variable dG xdCy base composition and liposomes composed of the cationic lipid DOTAP (ODN lipoplexes) were studied by differential pulse voltammetry at a glassy carbon electrode. Since lipoplexes are spontaneously formed by electrostatic interactions, the objective of the voltammetric study was to investigate their behaviour at the electrode surface/solution interface. It was verified that the peak current in the voltammograms for ODN lipoplexes was due to guanosine oxidation and that it was influenced both by the applied adsorption potential and the lipoplex (±) charge ratio used. It was found that for low ODN lipoplexes (±) charge ratios the peak current obtained was enhanced when compared to that registered with free ODN for the same concentration. This allowed a higher sensitivity in the determination of ODN by differential pulse voltammetry and a limit of detection of 5.5 ng/mL was achieved. A model that explains the organisation of ODN lipoplexes at the electrode surface/solution interface is proposed. The electrochemical results presented account for a better physicochemical characterisation of lipoplexes at charged interfaces, which can be important for the understanding and development of gene therapy vectors based on ODN lipoplexes.

KW - Cationic liposome

KW - Charged interface

KW - DOTAP

KW - Oligonucleotide lipoplex

KW - Voltammetry

UR - http://www.scopus.com/inward/record.url?scp=7644240649&partnerID=8YFLogxK

U2 - 10.1016/j.bios.2004.06.014

DO - 10.1016/j.bios.2004.06.014

M3 - Article

C2 - 15530794

AN - SCOPUS:7644240649

SN - 0956-5663

VL - 20

SP - 975

EP - 984

JO - Biosensors and Bioelectronics

JF - Biosensors and Bioelectronics

IS - 5

ER -