The development of new materials to improve analytical systems based on molecular receptors, mainly proteins and nucleic acids, highly sensitive, hard-working, reliable and easy to use, shows a huge potential and can offer very interesting responses to the addressed challenges today, such as real-time asssitance, multianalyte detection, high selectivity and portability, home health monitoring assays, among others.
Analytical systems developed in this work are characterized by micron-scale work (or less), require the controlled immobilization of biological element (biorreceptor) on the surface, and incorporate a degree of automation, especially in the early stages of the analytical process. The last and fundamental aim was the application of the most promising developments in specific issues, as competitive set-up for clinical diagnostic systems or enhancement of food safety.
Thus, in this thesis, methodologies for chemical modification of different materials (organic polymers, derived from silicon and tantalum oxide), which allowed the immobilization of biorreceptors of interest were purposed, for optical detection of molecular targets, with or without labeling.
In this sense, one of the researches was the development of micrometer scale analytical systems using CDs as analytical platforms. In this case it’s convenient to modify the polymeric materials CDs are made off (polycarbonate and polymethylmethacrylate), to print microarrays capture reagents. The reading of the results were carried out on the signals generated by absorbing tracers, using a modified CD reader for this purpose. This methodology was applied to the detection of avian influenza in saliva samples and single nucleotide polymorphism (SNPs) .
In other approach we worked with materials derived from silicon and tantalum oxide, which due to their dielectric properties and their hardness, are ideal for the development of platforms which incorporate nanostructures, forming together with other elements miniaturized sensor systems.
For silicon materials and derivatives a photonic device based on silicon nitride microrings slot waveguides deposited on silicon oxide substrate, were used for optical label free detection of analytes of interest. These analytical systems allow the detection of the substance immobilized on the nitride waveguide, without any previous labeling step, futhermore provide advantages such as high sensitivity of the slot waveguide. A biological model system (BSA-antiBSA) was studied by this device, showing the successful of these photonic structures applicability and the huge potential for the development of high sensitive integrated optoelectronic device capable of multianalyte detection in real samples.
Finally, on tantalum oxide materials the main advantages of covalent immobilization of biorreceptors face adsorption were studied, for the development of biochips for fluorescence microarrays detection using waveguide devices were studied. In these devices light travels through an area of Ta2O5 (highe refractive index) deposited on glass. Thus, the electromagnetic field generated as a result of guiding light is used as a source of excitation of the fluorophores. This methodology was applied to setting-up assays to detect hepatitis B antibodies in blood serum.