In the last few years we fabricated several competitive immunosensors for the analysis of IgG proteins [1-4]. In the present study, to reduce the excessively long time required for each competition measurement, we developed an innovative “direct” immunosensor method for IgG determination. Of course other immunosensors for the direct measurement of several different antigens have already been described in the literature [5-7]; these devices usually do not involve any “competition” procedure and generally do not make use of a marker, because in these probes the signal is often obtained directly as a result of immunocomplex formation (which may, for example, be a cause of potential variation in the membrane). Usually these devices have not been very successful for various reasons (poor repeatability and scarce selectivity) even though they afford a considerable reduction in analysis time. Nevertheless, we recently resumed studies on direct immunosensors types as part of research conducted on new electrochemical immunosensors developed for the analysis of other proteins [8] and designed to perform a “competition free” measurement using different operating schemes. In the latter case, however, unlike what is usually reported in the literature for this kind of immunosensors (i.e. “Label Free” measurement), an enzymatic marker was again used to perform a “not Label Free” electrochemical measurement, while the transducer used was of the classic amperometric type [8]. In the present research slightly different approach was used for the measurement of IgG although of the same kind, while the electrochemical transducer was of the potentiometric type. The following conclusions may be drawn: direct amperometric immunosensor methods of this kind, in which no competitive step is thus envisaged, but which however still use an enzymatic marker, are as sufficiently precise, robust and reliable as the corresponding competition methods. Moreover, they have the additional advantage of taking half the analysis time and furthermore do not display the drawbacks of poor selectivity and precision often found in several direct potentiometric methods reported in literature, which do not use an enzymatic marker, as the signal is produced directly as a result of the antibody complex formation. Of course also the affinity constant value was evaluated, which resulted of the order of 107 M-1 . Lastly some applications to real matrices, i. e. human serum and milk, were performed using the new direct immunodevice. Results were compared with those obtained by applying, to the same samples, also a classical competitive immunosensor method previously developed by the present authors. Correlation between two immunosensor methods was satisfactory.

P2.70: NEW “COMPETITION FREE”, BUT NOT “LABEL FREE” IMMUNOSENSOR METHOD FOR THE DIRECT DETERMINATION OF IgG / Martini, Elisabetta; Merola, Giovanni; Tomassetti, Mauro; Campanella, Luigi. - STAMPA. - (2013). (Intervento presentato al convegno Pharmaceutical and Biomedical Analysis (PBA 2013) Recent Development in Pharmaceutical Analysis (RDPA 2013) tenutosi a Bologna - Italy nel 30 June – 3 July 2013).

P2.70: NEW “COMPETITION FREE”, BUT NOT “LABEL FREE” IMMUNOSENSOR METHOD FOR THE DIRECT DETERMINATION OF IgG

MARTINI, ELISABETTA;MEROLA, GIOVANNI;TOMASSETTI, Mauro;CAMPANELLA, Luigi
2013

Abstract

In the last few years we fabricated several competitive immunosensors for the analysis of IgG proteins [1-4]. In the present study, to reduce the excessively long time required for each competition measurement, we developed an innovative “direct” immunosensor method for IgG determination. Of course other immunosensors for the direct measurement of several different antigens have already been described in the literature [5-7]; these devices usually do not involve any “competition” procedure and generally do not make use of a marker, because in these probes the signal is often obtained directly as a result of immunocomplex formation (which may, for example, be a cause of potential variation in the membrane). Usually these devices have not been very successful for various reasons (poor repeatability and scarce selectivity) even though they afford a considerable reduction in analysis time. Nevertheless, we recently resumed studies on direct immunosensors types as part of research conducted on new electrochemical immunosensors developed for the analysis of other proteins [8] and designed to perform a “competition free” measurement using different operating schemes. In the latter case, however, unlike what is usually reported in the literature for this kind of immunosensors (i.e. “Label Free” measurement), an enzymatic marker was again used to perform a “not Label Free” electrochemical measurement, while the transducer used was of the classic amperometric type [8]. In the present research slightly different approach was used for the measurement of IgG although of the same kind, while the electrochemical transducer was of the potentiometric type. The following conclusions may be drawn: direct amperometric immunosensor methods of this kind, in which no competitive step is thus envisaged, but which however still use an enzymatic marker, are as sufficiently precise, robust and reliable as the corresponding competition methods. Moreover, they have the additional advantage of taking half the analysis time and furthermore do not display the drawbacks of poor selectivity and precision often found in several direct potentiometric methods reported in literature, which do not use an enzymatic marker, as the signal is produced directly as a result of the antibody complex formation. Of course also the affinity constant value was evaluated, which resulted of the order of 107 M-1 . Lastly some applications to real matrices, i. e. human serum and milk, were performed using the new direct immunodevice. Results were compared with those obtained by applying, to the same samples, also a classical competitive immunosensor method previously developed by the present authors. Correlation between two immunosensor methods was satisfactory.
2013
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/543781
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