Are Nanobiosensors an Improved Solution for Diagnosis of Leishmania?

Leishmaniasis is one of the deadliest neglected tropical diseases affecting 12-15 million people worldwide, especially in middle- and low-income countries. Rapid and accurate diagnosis of the disease is important for its adequate management and treatment. Several techniques are available for the diagnosis of leishmaniasis. Among these, parasitological and immunological tests are most widely used. However, in most cases, the utilized diagnostic techniques are not good enough, showing cross-reactivity and reduced accuracy. In recent years, many new methods have been reported with potential for improved diagnosis. This review focuses on the diagnosis of Leishmania exploring the biosensors and nanotechnology-based options for their detection. New developments including the use of nanomaterials as fluorophores, fluorescence quenchers as reducing agents and as dendrimers for signal improvement and amplification, together with the use of aptamers to replace antibodies are described. Future research opportunities to overcome the current limitations on the available diagnostic approaches are also discussed.

Genosensors for differential detection of Zika virus.

Zika virus (ZIKV) is considered an emerging infectious disease of high clinical and epidemiological relevance. The epidemiological emergency generated by the virus in Latin America and Southeast Asia in 2014 evidenced the urgent need for rapid and acute diagnostic tools. The current laboratory diagnosis of ZIKV is based on molecular and serological methods. However, molecular tools need expensive and sophisticated equipment and trained personnel; and serological detection may suffer from cross-reactivity. In this context, genosensors offer an attractive alternative for field-ready, early and accurate diagnosis of ZIKV. This work reports on the development of genosensors for the differential detection of ZIKV and its discrimination from dengue (DENV) and chikungunya (CHIKV) homologous arboviruses. We designed specific capture and signal probes by bioinformatics, and prove their specificity to amplify the target genetic material by the polymerase chain reaction (PCR). The designed biotinylated capture and digoxigenin (Dig)-labeled signal probes hybridized the target in a sandwich-type format. An anti-Dig antibody labeled with the horseradish peroxidase (HRP) enzyme allowed for both optical and electrochemical detection. The genosensors detected the ZIKV genetic material in spiked serum, urine, and saliva samples and cDNA from infected patients, discriminating them from the DENV and ZIKV genetic material. The proposed system offers a step forward to the differential diagnosis of the ZIKV, closer to the patient, very promising for diagnosis and surveillance of this rapidly emerging disease.

Microfluidic-Based Genosensor To Detect Human Papillomavirus (HPV16) for Head and Neck Cancer.

High-risk human papillomavirus (HPV) infection, mainly with HPV16 type, has been increasingly considered as an important etiologic factor in head and neck cancers. Detection of HPV16 is therefore crucial for these types of cancer, but clinical tests are not performed routinely in public health systems owing to the high cost and limitations of the existing tests. In this article, we report on a potentially low-cost genosensor capable of detecting low concentrations of HPV16 in buffer samples and distinguishing, with high accuracy, head and neck cancer cell lines according to their HPV16 status. The genosensor consisted of a microfluidic device that had an active layer of a HPV16 capture DNA probe (cpHPV16) deposited onto a layer-by-layer film of chitosan and chondroitin sulfate. Impedance spectroscopy was the principle of detection utilized, leading to a limit of detection of 10.5 pM for complementary ssDNA HPV16 oligos (ssHPV16). The genosensor was also able to distinguish among HPV16+ and HPV16- cell lines, using the multidimensional projection technique interactive document mapping. Hybridization between the ssHPV16 oligos and cpHPV16 probe was confirmed with polarization-modulated infrared reflection-absorption spectroscopy, where PO2 and amide I and amide II bands from adenine and thymine were monitored. The electrical response could be modeled as resulting from an adsorption process represented in a Freundlich model. Because the fabrication procedures of the microfluidic devices and genosensors and the data collection and analysis can be implemented at low cost, the results presented here amount to a demonstration of possible routine screening for HPV infections.

Diagnostic tests for hepatitis C: recent trends in electrochemical immunosensor and genosensor analysis.

Hepatitis C is a liver disease that is transmitted through contact with the blood of an infected person. An estimated 150 million individuals worldwide have been chronically infected with the hepatitis C virus (HCV). Hepatitis C shows significant genetic variation in the global population, due to the high rate of viral RNA mutation. There are six variants of the virus (HCV genotypes 1, 2, 3, 4, 5, and 6), with 15 recorded subtypes that vary in prevalence across different regions of the world. A variety of devices are used to diagnose hepatitis C, including HCV antibody test, HCV viral load test, HCV genotype test and liver biopsy. Rapid, inexpensive, sensitive, and robust analytical devices are therefore essential for effective diagnosis and monitoring of disease treatment. This review provides an overview of current electrochemical immunosensor and genosensor technologies employed in HCV detection. There are a limited number of publications showing electrochemical biosensors being used for the detection of HCV. Due to their simplicity, specificity, and reliability, electrochemical biosensor devices have potential clinical applications in several viral infections.