Biosensors for Efficient Diagnosis of Leishmaniasis: Innovations in Bioanalytics for a Neglected Disease

Abstract

The need for reliable, fast diagnostics is closely linked to the need for safe, effective treatment of the so-called “neglected” diseases. The list of diseases with no field-adapted diagnostic tools includes leishmaniasis, shigella, typhoid, and bacterial meningitis. Leishmaniasis, in particular, is a parasitic disease caused by Leishmania spp. transmitted by infected phlebotomine sandfly, which remains a public health concern in developing countries with ca. 12 million people infected and 350 million at risk of infection. Despite several attempts, methods for diagnosis are still noneffective, especially with regard to specificity due to false positives with Chagas’ disease caused by Trypanosoma cruzi. Accepted golden standards for detecting leishmaniasis involve isolation of parasites either microscopically, or by culture, and in both methods specimens are obtained by invasive means. Here, we show that efficient distinction between cutaneous leishmaniasis and Chagas’ disease can be obtained with a low-cost biosensor system made with nanostructured films containing specific Leishmania amazonensis and T. cruzi antigens and employing impedance spectroscopy as the detection method. This unprecedented selectivity was afforded by antigen−antibody molecular recognition processes inherent in the detection with the immobilized antigens, and by statistically correlating the electrical impedance data, which allowed distinction between real samples that tested positive for Chagas’ disease and leishmaniasis. Distinction could be made of blood serum samples containing 10−5 mg/mL of the antibody solution in a few minutes. The methods used here are generic and can be extended to any type of biosensor, which is important for an effective diagnosis of many other diseases.

Liposomal systems as carriers for bioactive compounds

“…Such systems can be used as biomimetic models for studies of interaction with various hydrophobic drugs and membrane proteins, with potential applications in the field of immunology (vaccines and drugs targeting specific cell membranes). Liposomes associated with proteins can be used to study the activity of photosensitive dyes applied during photodynamic therapy (Bolfarini et al 2012;Longo et al 2012;Rocha et al 2012;Bicalho et al 2013;Faria et al 2015), as well for studies related to the ability of proteins to prevent, treat and/or act as nanosensors for various diseases (Daghastanli et al 2004;Santos et al 2006;Zucolotto et al 2007;Migliaccio et al 2008;Colhone et al 2009Colhone et al , 2015Calderon et al 2009a, b;Perinoto et al 2010;Paulovich et al 2011;Barbosa et al 2011;Salay et al 2011;Barros et al 2013;Fotoran et al 2015).…”

Information Visualization to Enhance Sensitivity and Selectivity in Biosensing

“…Several kinds of sensing elements and detection methods have been studied for e-noses and mainly e-tongues [45,51,[57][58][59][60][61][62], which allow applicability in fields as food [57,[62][63][64][65][66], wines [67], water [68] and pharmaceutical analysis [66]. The importance of the e-tongues and e-noses to biosensing stems from the possible extension through the incorporation of sensing units capable of molecular recognition [69][70][71][72].…”

“…The power of visualization methods has been combined with an extended e-tongue technology [72,92] to solve a major problem in biosensing for clinical diagnosis of two tropical diseases, namely Leishmaniasis and Chagas' Disease caused by Trypanosoma cruzi. It so happens that even in sophisticated immunoassays, many false positives occur [93,94].…”

“…It so happens that even in sophisticated immunoassays, many false positives occur [93,94]. Perinotto et al [72] addressed this problem with impedance spectroscopy measurements with a sensor array containing four sensing units, two of which had immobilized antigens with molecular recognition capability toward anti-Leishmania and anti-T. Cruzi antibodies in LbL films. A cartoon with the biosensing device (one sensing unit) is given in Fig.…”

“…7, it was possible to distinguish between the samples made with a buffer to which various concentrations of antibodies were added [72]. However, when all the ''real'' samples made with blood serum of infected animals were included full distinction could not be reached, encouraging investigation of other projection techniques.…”