Rapid method using two microbial enzymes for detection of L-abrine in food as a marker for the toxic protein abrin

Gaps in forensic toxicological analysis: The veiled abrin

Abrus precatorius is an herbaceous, flowering plant that is widely distributed in tropical and subtropical regions. Its toxic component, known as abrin, is classified as one of the potentially significant biological warfare agents and bioterrorism tools due to its high toxicity. Abrin poisoning can be utilized to cause accidents, suicides, and homicides, which necessitates attention from clinicians and forensic scientists. Although a few studies have recently identified the toxicological and pharmacological mechanisms of abrin, the exact mechanism remains unclear. Furthermore, the clinical symptoms and pathological changes induced by abrin poisoning have not been fully characterized, and there is a lack of standardized methods for identifying biological samples of the toxin. Therefore, there is an urgent need for further toxicopathologic studies and the development of detection methods for abrin in the field of forensic medicine. This review provides an overview of the clinical symptoms, pathological changes, metabolic changes, toxicologic mechanisms, and detection methods of abrin poisoning from the perspective of forensic toxicology. Additionally, the evidence on abrin in the field of forensic toxicology and forensic pathology is discussed. Overall, this review serves as a reference for understanding the toxicological mechanism of abrin, highlighting the clinical applications of the toxin, and aiding in the diagnosis and forensic identification of toxin poisoning.

S-Nitrosothiol-Impregnated Silicone Catheter for Colorimetric Sensing of Indole and E. coli: Toward On-Body Detection of Urinary Tract Infections

Although there are many techniques to detect pathogenic bacteria, most of them are only suited for in vitro diagnostics. We report a urinary catheter-based colorimetric sensor for potential on-body detection of E. coli, the most prevalent bacterial species in urinary tract infections associated with the use of urinary catheters. In urine, indole is secreted by E. coli and reacts with a nitrosating agent incorporated in a silicone catheter. A red dimeric product, indoxyl red, is generated within silicone rubber to allow for color-based indole sensing with high sensitivity, linearity, and specificity. This reaction is initiated by the nitrosation reaction of indole at its C-3 position via reagents like sodium nitrite or S-nitroso-N-acetyl-penicillamine under aerobic conditions. The generated 3-nitrosoindole undergoes tautomerization, dimerization, and deoximation to form indoxyl red with high absorbance at 537 nm. In contrast to other indole sensors, the presented method can be applied in real catheters to detect indole and E. coli in biofluids such as urine. The is because (1) S-nitroso-N-acetyl-penicillamine, the nitrosating agent, can be impregnated into silicone elastomers, (2) indole from urine is extracted into silicone due to its hydrophobicity, and (3) the high acidity and oxygen solubility of silicone facilitates the sensing reaction within the silicone matrix. This silicone-based colorimetric sensor clearly differentiates E. coli below and above 10⁵ CFU/mL, which is the threshold concentration of bacteriuria. We expect that early diagnosis of urinary tract infections using the naked eye is possible by functionalizing an exposed section of urinary catheters with the proposed molecular probe.

Bio-barcode triggered isothermal amplification in a fluorometric competitive immunoassay for the phytotoxin abrin

Abrin is one of the most toxic phytotoxins to date, and is a potential biological warfare agent. A bio-barcode triggered isothermal amplification for fluorometric determination of abrin is described. Free abrin competes with abrin-coated magnetic microparticles (MMP) probes to bind to gold nanoparticle (AuNP) probes modified with abrin antibody and bio-barcoded DNA. Abundant barcodes are released from the MMP-AuNP complex via dithiothreitol treatment. This triggers an exponential amplification reaction (EXPAR) that is monitored by real-time fluorometry, at typical excitation/emission wavelengths of 495/520 nm. The EXPAR assay is easily operated, highly sensitive and specific. It was used to quantify abrin in spiked commercial samples. The detection limit (at S/N = 3; for n = 6) is 5.6 pg·mL^-1 which is considerably lower than previous reports. This assay provides a universal sensing platform and has great potential for determination of various analytes, including small molecules, proteins, DNA, and cells. Graphical abstract Schematic representation of the bio-barcode triggered exponential amplification reaction (EXPAR) for a fluorometric competitive immunoassay for abrin. The limit of detection is 5.6 pg mL^-1 with a large dynamic range from 10 pg mL^-1 to 1 µg mL^-1.

Label-free detection of biotoxins via a photo-induced force infrared spectrum at the single-molecular level

Schematic illustration of photo-induced force microscopy combine principal component analysis detected and distinguish single molecule particles of biotoxins AT, RT/ETX with label-free.