Da micologia clássica à nanotecnologia: aumento da eficiência para detecção de micoses sistêmicas e aplicação de um novo teste rápido e de baixo custo para diagnóstico de criptococose

Abstract

Cryptococcosis is a disease caused by yeasts of the Cryptococcus genus, mainly by neoformans and gattii species. In Brazil, this disease has the largest number of cases in all of Latin America, being the fungal infection that most affects the central nervous system. In relation to diagnosis, immunological methods have low sensitivity, for example, the ELISA detection method is quite laborious, requires fine training of personnel and availability of expensive equipment to obtain results. The immunochromatographic test is faster and simpler to perform, but fails to generate false-positive results due to the occurrence of cross-reaction with other microorganisms. Considering the important gaps in the diagnosis of cryptococcosis caused by the flaws inherent to each method, it is of great importance to develop and apply rapid, sensitive, specific tests, which are easy to handle and accessible in environments far from large centers. Thus, this work aims to use photonics and nanotechnology for a new diagnostic method through generation of nanosensor capable of binding to criptococcal antigens and photonics measures that enable the detection and characterization of these bindings. For this purpose, gold nanorods (GNRs) have been synthesized and functionalized with monoclonal antibody 18B7, capable of recognizing fragments of the cryptococcal polysaccharide capsule, specifically fragments of glucoroxylomannan (GXM). The nanorods functionalized (nanosensors) were tested using serum from infected mice and healthy mice by a portable light- scattering spectrometer (EPEL). The optical instrument uses measurements of dynamic light scattering and is able to detect, in a few minutes, presence of fragments cryptococcal polysaccharide capsule. Thus, in this work proof of concept is demonstrated of a point of care technology for diagnostics of criptococcosis.