ABSTRACT
Strongyloidiasis is a helminthiasis of neglected condition that has no gold standard parasitological diagnosis due to the intermittent release of larvae in feces. This study aimed to use an scFv (single chain variable fragment) obtained by Phage Display, previously validated to detect immune complexes in serum samples from individuals infected with Strongyloides stercoralis by enzyme-linked immunosorbent assay (ELISA). Now the ability of scFv to detect the immune complexes was verified by immunofluorescence, flow cytometry using magnetic beads and surface plasmon resonance (SPR). As ELISA, the SPR, immunofluorescence and flow cytometry demonstrated the ability of scFv to detect immune complexes in sera from individuals with strongyloidiasis and discriminate them from sera of individuals with other parasitic diseases and healthy individuals. Besides de conventional ELISA, the novel approaches can also be promptly applied as auxiliary diagnostic tools to the existing parasitological method for accurate diagnosis of human strongyloidiasis.
Subject(s)
Strongyloides stercoralis , Strongyloidiasis , Animals , Antibodies, Helminth , Enzyme-Linked Immunosorbent Assay , Feces , Humans , Immunoglobulin G , Serologic Tests , Strongyloidiasis/diagnosisABSTRACT
BACKGROUND: Rheumatoid arthritis is the most common inflammatory autoimmune disease in the world. Recently new targets for its detection were developed as alternatives to classic biomarkers, including the M-12 peptide, that mimics carbonic anhydrase III. Thus, the application of this peptide for the development of new detection devices is attractive. OBJECTIVE: Our goal was to construct a modified electrode for immobilization of M-12 peptide and detection of a rheumatoid arthritis biomarker in serum of patients. METHODS: 3-Hydroxybenzoic acid was electropolymerized onto graphite electrodes, and M-12 peptide was immobilized by adsorption. Negative and positive serum samples for rheumatoid arthritis were diluted and applied onto the electrode. Detection was carried in potassium ferrocyanide/ ferricyanide solution by differential pulse voltammetry. Atomic force microscopy and scanning electron microscopy were used to evaluate electrode surfaces. RESULTS: Cyclic voltammograms indicated the poly(3-hydroxybenzoic acid) formation and increase of electroactive area. Immobilization of M-12 probe increased current by 1.2 times, and negative serum addition caused no suitable difference. However, positive serum showed expressive decrease in the current signal of about 2.2 times, possibly due to steric hindrance when the anti-CA3 antibody interacts with the M-12 peptide, decreasing the electron transfer. Microscopies images corroborated with the electrochemical detection, showing evident changes in the morphology of the electrode surfaces. CONCLUSION: The bioelectrode was able to discriminate positive and negative serum samples of rheumatoid arthritis by a considerable decrease in the current signal value. Morphological analyses supported the electrochemical results. Thus, the constructed bioelectrode offers a new platform for detection of rheumatoid arthritis.
Subject(s)
Arthritis, Rheumatoid/diagnosis , Biosensing Techniques/instrumentation , Peptides/chemistry , Arthritis, Rheumatoid/blood , Biomarkers/blood , Biomimetic Materials/chemistry , Biosensing Techniques/methods , Electrodes , Graphite/chemistry , Humans , Microscopy, Atomic Force , Microscopy, Electron, ScanningABSTRACT
The compound 3-hydroxyphenylacetic acid (3-HPA) has been used as a monomer in the synthesis of polymeric films by electropolymerization; these films serve as supports for the immobilization of biomolecules in electrochemical biosensors. To assist in the elucidation of the mechanism of 3-HPA electropolymerization, a systematic quantum mechanical study was conducted. In addition to the monomer, all possible intermediates and the probable oligomers formed during the electropolymerization were investigated using a density functional theory (DFT) method combined with a previous conformational analysis performed with the aid of the RM1 semi-empirical method or a Monte Carlo conformational analysis with the force field OPLS-2005. From the data analysis combined with the experimental results, a mechanism was proposed for the main route of formation of the polymeric films. The mechanism involves the formation of polyethers from the coupling of phenoxide radicals and radicals based on the aromatic ring.
Subject(s)
Models, Molecular , Phenylacetates/chemistry , Polymerization , Polymers/chemistry , Computer Simulation , Electrochemistry , Electrons , Membranes, Artificial , Molecular Conformation , Quantum Theory , Spectroscopy, Fourier Transform Infrared , Surface Properties , ThermodynamicsABSTRACT
Based on biological molecules combined with nanostructured components, the news generations of electrochemical biosensors can employ different transducers (potentiometric, amperometric and impedimetric) converting the chemical information into a measurable amperometric signal. Following this contemporary theme, our main focus in this review is to discuss different methodologies for application in biosensing, whose signal transduction is based on electrochemical principles. We apply a discussion on recent trends involving different nanostructured materials, but without daring to contemplate all nanomaterials incessantly cited in literature, which leads us to believe that this moment is an unprecedented revolution in the preparation of electrochemical biodevices. Besides, some structures of bio-nano interface and different electrochemical biosensors involved in diagnosis systems are also discussed. We outline in several parts of the report how nanoscience technologies are emerging in diagnostic medicine, as well as convergence of electrochemistry and bio-nanoscience. Our hopes for this review are that it can help different categories of researchers to understand the broad application area of electrochemistry and bioelectrochemistry, in order to detecting several types of diseases and biological phenomena.
