A joint action of aptamers and gold nanoparticles chemically trapped on a glassy carbon support for the electrochemical sensing of ofloxacin

• Published in: Sensors and actuators. B, Chemical Chemical, 2017-03, Vol.240, p.1024-1035
• Main Authors: Pilehvar, Sanaz, Reinemann, Christine, Bottari, Fabio, Vanderleyden, Els, Van Vlierberghe, Sandra, Blust, Ronny, Strehlitz, Beate, De Wael, Karolien
• Format: Article
• Language: English
• Subjects: Antibiotics; Attachment; Au nanoparticles; Covalence; Covalent attachment; Detection; Drinking water; Electrochemical aptasensor; Electrochemistry; Electrodes; Environmental monitoring; Glassy carbon; Gold; Immobilization; Nanoparticles; Ofloxacin; Organic chemistry; Reproducibility; Sensors; Sewage treatment plants; Strategy; Water quality
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2016.09.075

•A new electrochemical aptasensing strategy is developed based on chemically entrapped AuNPs onto a glassy carbon electrode (GCE) surface for the detection of ofloxacin.•The covalently anchored AuNPs on the GCE surface were used as electronic bridges, to enhance the probe immobilization capacity and to increase the long-term stability of the attached aptamers.•The sensor exhibited high specificity toward ofloxacin with a limit of detection (LOD) of 1nM.•The developed aptasensing method was successfully applied to determine ofloxacin in tap water and effluent sewage plant water samples. A joint action of ssDNA aptamers and electrochemistry is a key element in developing successful biosensing platforms, since aptamers are capable of binding various targets with high specificity, and electrochemistry is one of the most sensitive techniques for on-site detections. A continuous search for improved immobilization and sensing strategies of aptamers on transducer surfaces resulted in the strategy presented in this article. The strategy is based on the covalent attachment of gold nanoparticles on the surface of glassy carbon electrodes through sulfhydryl-terminated monolayer, acting as a glue to connect AuNPs on the electrode. The covalently attached gold nanoparticles modified glassy carbon electrodes have been applied for the efficient immobilization of thiolated ssDNA probes, with a surface coverage of about 8.54×1013 molecules cm−2 which was 7-fold higher than that on the electrochemically deposited gold nanoparticles. Consequently, improved sensitivity, good reproducibility and stability are achieved for electrochemical aptasensor. Combined with the high affinity and specificity of an aptamer, a simple, novel, rapid, sensitive and label-free electrochemical aptasensor was successfully fabricated for ofloxacin (OFL) detection. The linear dynamic range of the sensor varies between 5×10−8 to 2×10−5M OFL with a detection limit of 1×10−9M OFL. A potential application in environmental monitoring was demonstrated by using this sensing strategy for the determination of OFL in (experimentally spiked) real samples such as tap water and effluent of sewage treatment plant. The proposed nanoaptasensor combines the advantages of the covalent attachment of neatly arranged AuNPs (enlarged active surface area and strengthened electrochemical signal) and the elimination of labels for the amplified detection of OFL, with the covalent attachment of highly specific aptamers to the