Desenvolvimento de nanomateriais e nanocompósitos para aplicação em detecção química e biológica por espalhamento de luz

Abstract

The detection of chemical compounds and biological structures is of great importance in various fields of human activity, especially in matters of health, such as in medical diagnosis. Currently, the most widely used method to this end is the ELISA (Enzyme Linked Immune Sorbent Assay), which is based on the detection and quantification of specific antibodies. However, this method uses heterogeneous protocols, with several distinct steps and still have low sensitivity and selectivity. The various other methods of molecular recognition, usually make use of a conjugate between a receptor and molecules or biomolecules of interest, and in many of these methods, the receptors are coupled with metal nanoparticles that are detected by optical techniques. Many chemical detection methods are being studied recently, especially the methods involving light scattering, such as Raman spectroscopy, through the so-called SERS effect, and the dynamic light scattering technique. In this work, we developed two new technologies of chemical and biological detection based on light scattering. The first uses nanocomposites between carbon nanomaterials and gold nanorods as substrates for Raman spectroscopy measurements by SERS technique. With these substrates it was possible to amplify the Raman signal by orders of magnitude, which provides an ultrasensitive detection chemistry in order to picomolar concentration. The second technology is a new method for specific detection of antibodies based on the rotational dynamics of gold nanorods through dynamic scattering measurements of unpolarized light. These new technologies are more sensitive and effective than currently available technologies in the market, providing a more specific and rapid chemical and biological detection.