On the contrary, for immunosensors, one of the immunoreagents is immobilized on the surface of the transducer, and a direct physical signal is produced selleck kinase inhibitor when the immunochemical interaction occurs. This label-free detection represents an essential advantage of immunosensors as compared to label-dependent immunoassays [7].Immunosensors are biosensors that use antibodies (Ab) or antigens (Ag) as the specific sensing element and provide concentration-dependent signals [8]. Depending on the method of signal transduction, immunosensors Inhibitors,Modulators,Libraries may be divided into four basic groups: electrochemical, optical, piezoelectric and thermometric [9]. Among these different types of immunosensors, the electro-chemical ones show more potential thanks to their higher sensitivity, Inhibitors,Modulators,Libraries higher speed and permanent control.
Valera��s Inhibitors,Modulators,Libraries group [10�C15] has reported a series of methods using electrochemical impedance immunosensors for atrazine detection based on the interdigitated microelectrode array produced by a competitive reaction. The Ciumasu group also reported a portable miniaturized immunosensor for atrazine and diuron detection using a competition assay method [16]. It is well known that competitive assays are complex. The direct determination of a pesticide by immobilizing a suitable antibody on the electrode surface could simplify the assay process and shorten the detection time. Hu et al. reported a label-free electrochemical immunosensor based on gold nanoparticles for the direct determination of paraoxon. The recovery of paraoxon in river water using the developed immunosensor ranged between 93.
5�C109% Inhibitors,Modulators,Libraries [6]. For electrochemical immnunosensors, because pesticides are small molecule compounds, in fact, the electro-signal change due to the immunoreaction AV-951 is usually faint. Thus, the use of direct immunoreactions for pesticide detection is still a challenge.During the fabrication of an immunosensor, the immobilization of the antigen or antibody onto the electrode surface is a difficult and crucial step, which heavily influences the performance of the resulting immunosensor. At present the main immobilization approaches include the electropolymerization entrapment technique using, for example, a polypyrrole monolayer film [17], polypyrrole/polybilayer film [18], self-assembled monolayers [19], or sol-gel film [20] etc.
Sol-gel technology provides a unique means to prepare a three-dimensional network suited for the encapsulation of a variety of biomolecules. Thus, here, we select silica gel sol gel (SiSG) as immobilizing agent to offer a biocompatible microenvironment for confining selleck the antibody and foreshadow the great potentiality of this immobilizing agent in the development of biosensors [21]. To the best of our knowledge, such a label-free, direct immunoreaction immunosensor with a silica SiSG immobilized antibody for carbofuran pesticide detection has not yet been reported.