Electrochemical DNA Biosensor That Detects Early Celiac Disease Autoantibodies

Recent Advances in Biosensors for Diagnosis of Autoimmune Diseases

Over the last decade, autoimmune diseases (ADs) have undergone a significant increase because of genetic and/or environmental factors; therefore, their simple and fast diagnosis is of high importance. The conventional diagnostic techniques for ADs require tedious sample preparation, sophisticated instruments, a dedicated laboratory, and qualified personnel. For these reasons, biosensors could represent a useful alternative to these methods. Biosensors are considered to be promising tools that can be used in clinical analysis for an early diagnosis due to their high sensitivity, simplicity, low cost, possible miniaturization (POCT), and potential ability for real-time analysis. In this review, recently developed biosensors for the detection of autoimmune disease biomarkers are discussed. In the first part, we focus on the main AD biomarkers and the current methods of their detection. Then, we discuss the principles and different types of biosensors. Finally, we overview the characteristics of biosensors based on different bioreceptors reported in the literature.

Antibody detection by agglutination-PCR (ADAP) assays for the analysis of tissue transglutaminase autoantibodies in celiac disease

BACKGROUND & AIMS

Tissue transglutaminase autoantibodies (tTGA) are used as diagnostic markers of celiac disease. Different methods have been developed for the detection of tTGA of which enzyme-linked immunosorbent assays (ELISA), radiobinding assays (RBA) and electrochemiluminescence (ECL) assays are the most commonly used. Here we aimed to evaluate a novel antibody determination by agglutination-PCR (ADAP) assay for the detection of tTGA.

METHODS

Included were 126 children with untreated celiac disease (UCD), 64 disease controls (DC), 21 children with potential celiac disease (PCD), and 1501 children from the general population. Tissue TGA were determined using an automated ADAP assay platform and compared with two RBAs for the detection of IgA-tTG and IgG-tTG, respectively.

RESULTS

ADAP detected tTGA in 123/126 (97.6%) UCD children compared with 122/126 (96.8%) using RBA-IgA-tTG and RBA-IgG-tTG (p > 0.9999), respectively. Among DC, ADAP detected 5/64 (7.8%) children with tTGA compared with 4/64 (6.3%) with RBA-IgA-tTG (p > 0.9999) and 8/64 (12.5%) with IgG-tTG (p = 0.5600), respectively. Tissue TGAs were equally detected in children with PCD in both assays. In the general population, 4/1501 (0.3%) were tTGA positive using ADAP compared with 3/1501 (0.2%) for RBA-IgA-tTG and RBA-IgG-tTG (p > 0.9999), respectively. The area under the curves (AUCs) were 0.998 for ADAP, 0.994 for RBA-IgA-tTG, and 0.999 for RBA-IgG-tTG, respectively.

CONCLUSIONS

No difference in specificity and sensitivity of tTGA for the diagnosis of celiac disease was reported between ADAP and RBA. ADAP could be recommended as the first-line screening method of larger populations for celiac disease.

Modern Electrochemical Biosensing Based on Nucleic Acids and Carbon Nanomaterials

To meet the requirements of novel therapies, effective treatments should be supported by diagnostic tools characterized by appropriate analytical and working parameters. These are, in particular, fast and reliable responses that are proportional to analyte concentration, with low detection limits, high selectivity, cost-efficient construction, and portability, allowing for the development of point-of-care devices. Biosensors using nucleic acids as receptors has turned out to be an effective approach for meeting the abovementioned requirements. Careful design of the receptor layers will allow them to obtain DNA biosensors that are dedicated to almost any analyte, including ions, low and high molecular weight compounds, nucleic acids, proteins, and even whole cells. The impulse for the application of carbon nanomaterials in electrochemical DNA biosensors is rooted in the possibility to further influence their analytical parameters and adjust them to the chosen analysis. Such nanomaterials enable the lowering of the detection limit, the extension of the biosensor linear response, or the increase in selectivity. This is possible thanks to their high conductivity, large surface-to-area ratio, ease of chemical modification, and introduction of other nanomaterials, such as nanoparticles, into the carbon structures. This review discusses the recent advances on the design and application of carbon nanomaterials in electrochemical DNA biosensors that are dedicated especially to modern medical diagnostics.

Elucidation of DNA-Eltrombopag Binding: Electrochemical, Spectroscopic and Molecular Docking Techniques

Eltrombopag is a powerful adjuvant anticancer drug used in treating MS (myelodysplastic syndrome) and AML (acute myeloid leukemia) diseases. In this study, the interaction mechanism between eltrombopag and DNA was studied by voltammetry, spectroscopic techniques, and viscosity measurements. We developed a DNA-based biosensor and nano-biosensor using reduced graphene oxide-modified glassy carbon electrode to detect DNA-eltrombopag binding. The reduction of desoxyguanosine (dGuo) and desoxyadenosine (dAdo) oxidation signals in the presence of the drug demonstrated that a strong interaction could be established between the eltrombopag and dsDNA. The eltrombopag-DNA interaction was further investigated by UV absorption and fluorescence emission spectroscopy to gain more quantitative insight on binding. Viscosity measurements were utilized to characterize the binding mode of the drug. To shed light on the noncovalent interactions and binding mechanism of eltrombopag molecular docking and molecular dynamics (MD), simulations were performed. Through simultaneously carried out experimental and in silico studies, it was established that the eltrombopag binds onto the DNA via intercalation.