The diagnosis of feline leishmaniasis remains a public health challenge due to the lack of
specific protocols for cats. The application of biosensors as an analytical tool has been a
favorable alternative. Thus, this study proposed the development of a piezoelectric
immunosensor for the qualitative detection of anti-Leishmania infantum A2 antigen antibodies
in feline serum. Recombinant protein A2 from L. infantum was used as antigen and feline serum
known to be positive was used as a sample. A quartz crystal microbalance with dissipation
monitoring was used to carry out the tests based on two immobilization protocols: simple
adsorption and self-assembled monolayer (SAM) of the thiol type implemented by carbon
disulfide (CS2). Nanogravimetric measurements were performed using specific software,
generating a real-time graph. The analytical response of each immunosensor was evaluated by
varying the frequency as a function of time before and after the addition of the sample. The
biorecognition capacity of the immunosensor was tested by incubating a feline serum sample
positive for visceral leishmaniasis, being considered positive in the immunosensor by
decreasing the sensor's resonance frequency. The results obtained by the analysis of the
reactivity of immunosensors prepared by both simple adsorption and CS2-mediated SAM
demonstrated a pattern of response indicative of detection of anti-A2 antigen antibodies present
in feline serum from the immobilization of L. infantum recombinant A2 antigen , generating
perspectives on the potential for application in the screening of serological samples of cats in
endemic areas, which may help to understand their participation in the epidemiology of visceral
leishmaniasis and, consequently, contribute to its monitoring and control, being a promising
tool to support epidemiological and diagnostic studies of the disease in felines.
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