Higson, Seamus P. J.Garifallou, Goulielmos-Zois2009-12-152009-12-152008http://hdl.handle.net/1826/4077This PhD project was funded by the European Union Framework 6 ELISHA programme as part of the ELISHA programme. The aim of the research was focused towards the development of point-of-care, simple, cost-efficient and reliable impedimetric immunosensors for the rapid detection of important antigens such as ciprofloxacin and digoxin. Through the cooperation of the 9 involved partners a number of protocols have been developed for sensor fabrication and sample testing that allow both rapid and reliable detection of a range of antigens. This work describes in depth, the use of polymers and cyclic voltammetry for electrode surface modification, the use of the avidin-biotin system for antibody immobilisation and finally the use of Electrochemical Impedance Spectroscopy for antigen detection. We report here the successful development of electrochemical impedimetric carbon based immunosensors for the detection of free-form and chelated ciprofloxacin (both in laboratory buffer and milk), digoxin and green fluorescent protein. It was observed during this work that unavailability of sufficient quantities of the monoclonal antibodies could lead to early sensor saturation and hence a less extended antigen detection range, while very low quantities of immobilised antibodies could also give rise to erroneous results. The immunosensors towards ciprofloxacin detected the respective antigen when this was present between 1 ng ml-1 and 10 μg ml-1 in PBS buffer and 0.1 ng ml-1 to 10 μg ml-1 when the antigen was added to milk samples. The developed digoxin immunosensors could detect digoxin between the concentrations of 0.1 ng ml-1 and 10 μg ml-1. Lower detection limits where observed for the sensors targeting GFP which could detect their respective antigen at concentrations as low as 100 pg ml-1. The tested concentration range of the latter sensors was extended up to 100 ng ml-1.enThesis or dissertation