We have developed a cost-effective and portable graphene-enabled biosensor to detect Zika virus with a highly specific immobilized monoclonal antibody. Field Effect Biosensing (FEB) with monoclonal antibodies covalently linked to graphene enables real-time, quantitative detection of native Zika viral (ZIKV) antigens. The percent change in capacitance in response to doses of antigen (ZIKV NS1) coincides with levels of clinical significance with detection of antigen in buffer at concentrations as low as 450pM. Potential diagnostic applications were demonstrated by measuring Zika antigen in a simulated human serum. Selectivity was validated using Japanese Encephalitis NS1, a homologous and potentially cross-reactive viral antigen. Further, the graphene platform can simultaneously provide the advanced quantitative data of nonclinical biophysical kinetics tools, making it adaptable to both clinical research and possible diagnostic applications. The speed, sensitivity, and selectivity of this first-of-its-kind graphene-enabled Zika biosensor make it an ideal candidate for development as a medical diagnostic test.

The lethal toxin produced during Bacillus anthracis infection is a complex of protective antigen, which localizes the toxin to the cell receptor, and lethal factor (LF), a zinc-dependent endoproteinase whose known targets include five members of the mitogen-activated protein kinase kinase (MAPKK) family of response regulators. We have developed a method for detecting functional LF in serum. Anti-LF murine monoclonal antibodies immobilized on magnetic protein G beads were used to capture and concentrate the LF from serum. The captured LF was exposed to an optimized MAPKK-based peptide substrate, which it hydrolyzed into two smaller peptides. The LF cleavage products were then analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MS) and quantified by isotope dilution-MS. The entire analytical method can be performed in less than 4 h with detection of LF levels as low as 0.05 ng/mL. The method was used to quantify LF levels in serum from rhesus macaques infected with B. anthracis. Serum samples obtained at day 2 postinfection contained 30-250 ng/mL LF and illustrated the clear potential to detect LF earlier in the infection cycle. This method represents a highly specific and rapid diagnostic tool for early anthrax and has a potential additional role as a research tool for understanding toxemia and effects of medical countermeasures for anthrax.Anthrax is caused by infection with Bacillus anthracis, a sporeforming, Gram-positive bacterium. The dormant spore is resistant to extremes of temperature, desiccation, and a variety of chemical treatments. 1 The stability, ease of production, and infectious capacity of the spores confer B. anthracis with high potential as a biological weapon. 2 B. anthracis spores gain entry through a dermal abrasion or gastrointestinal lesion causing cutaneous or gastrointestinal anthrax, respectively, or are inhaled, causing pulmonary anthrax. Systemic infection from the progression of any of the three forms of anthrax frequently results in secondary shock, multiple organ failure, and death. 3 Early diagnosis is critical for effective treatment of pulmonary (inhalation) anthrax. 4 In the U.S. bioterrorism attacks of 2001, pulmonary anthrax had a 45% fatality rate despite antibiotic treatment and aggressive supportive care of the patients. 5,6 The two exotoxins of B. anthracis are binary combinations of protective antigen (PA) and either edema factor (EF) or lethal factor (LF). 7 The complex of PA and EF forms edema toxin (ETx) and PA complexed with LF forms lethal toxin (LTx). PA is secreted as an 83-kDa protein (PA83), which binds to known receptors TEM8 (tumor endothelium marker 8) 8 and CMG2 (capillary morphogenesis protein 2) 9 on the surface of target cells where it is cleaved by a furin-like cell surface protease to a 63-kDa protein (PA63). 10 PA83 may also be cleaved to the PA63 conformer by serum proteases. 11 Cleavage causes a conformational