Resumen de Screening methodologies for the determination of water contaminant residues by compact disk technology
The contamination of water resources with many industrial, agricultural and other chemicals is one of the key environmental problems that humanity is facing nowadays. Despite the fact that they are usually present at very low concentration, they possess a significant risk to aquatic and human life.
To address this issue many national and international institutions set different regulations to monitor and control the water quality.
Currently, the monitoring of compounds included in official watch lists is conducted by chromatographic and mass spectroscopic methods. These techniques are approved as "gold standards" for analytical quantitation of organic residues in water. Although they are sensitive and reproducible, cannot be used on-site. The need of sampling and centralized laboratory measurements makes not only the overall cost high but lowering the efficiency of the analysis.
Therefore, there is an urgent need to develop suitable field methods to facilitate the in situ measurements at a low cost. Biosensors are therefore an alternative technology that can provide sensitive results in a fast and affordable way.
This thesis has focused on the development of a biosensor based on immunoassays and compact disk technology, for the multiplex detection of priority water contaminants.
As the methods based on the immunorecognition events are challenging in terms of the selectivity and sensitivity, the major part of the thesis was the selection of the immunoreagents, assay form and procedure. For the detection part, gold nanostructures were selected as sensitive tags for signal enhancement. Therefore, different nanoparticles were studied in order to select the optimal size in terms of the signal enhancement, sensitivity and antibody amount used. Also, the assays performances with signal enhancement and without any amplification were evaluated. The best immunoassay was selected for developing the multiplexed assay.
Furthermore, an approach to improve the readout sensitivity of microimmunoassays based on used of gold nanoparticles as both capture and detection species was demonstrated. The method is based on the performance of the immunorecognition event in a homogeneous mode and detection part in the heterogeneous format.
Finally, representative water samples were analysed to confirm the applicability of the multi-residue assay. The analytical properties have been established for each methodology and the obtained results have been validated by comparison with reference techniques.
The investigations carried out in this work, have resulted in new insights in immunoassay technique that could be useful for screening applications.
