In The February Issue
• New! Aptamer to DEHP
• Aptamers to Metabolites of Nerve Agents Sarin and VX
• Detecting Chemical Contaminants with Aptamers
New! Aptamer to DEHP
A selective aptamer for Di(2-ethylhexyl)phthalate, or DEHP, is now available from Base Pair. DEHP is found in many consumer products and medical devices manufactured from PVC/vinyl. Ingestion of DEHP through contaminated food or water and extended exposure through medical devices (such as dialysis tubing) pose current health concerns. Researchers at Texas A&M University have recently developed a sensor for sensitive detection of DEHP using the Base Pair aptamer. View Product Page
Aptamers for Quantitation of Nerve Agent Metabolites
Exposure to organophosphorus nerve agents can cause symptoms ranging from tear production and confusion to vomiting, paralysis, and death. Detection of low-level exposure and identification of the specific nerve agent applied are huge challenges. Researchers at Vanderbilt University and the CDC have developed a method for quantifying metabolites of two prominent nerve agents, Sarin and Venomous Agent X, in serum using aptamers selected by Base Pair Biotechnologies. Contact Base Pair to inquire about aptamers to VX and Sarin metabolites and similar compounds.
Detecting Chemical Contaminants with Aptamers
Researchers and consumers are becoming increasingly concerned about chemical contaminants in food and in the environment. From chemicals leaching from plastic containers to residues of antibiotics and pesticides used in food production to the intentional release of chemical toxins, the potential hazards of exposure, especially for developing infants and children, are gradually coming to light.
Current tests for chemical contaminants include chromatography, mass spectrometry, and ELISAs (enzyme-linked immunosorbent assays), but these tests are expensive and time-consuming. The development of fast, accurate, economical field-based tests is more important than ever (3).
Aptamer Advantages in Contamination Detection
Aptamers can be selected against non-immunogenic or toxic compiounds, including small molecules, metabolites, bacterial/viral proteins, and toxins. Aptamers can be selected to differentiate between very similar chemical compounds. In vitro selection enables discovery of aptamers that perform in a broad range of sample matrices, accommodating environmental, industrial, and food/beverage testing. Stability of aptamers in a wide range of temperatures makes them ideal candidates for field-based tests utilizing re-usable sensors, lateral flow assays, and solution-based assays. Because aptamers are chemically synthesized, they offer excellent lot-to-lot reproducibility and guaranteed supply (3).
Chemicals from Plastics
Several classes of chemicals which leach from plastics into food, beverages, and the environment have presented health concerns. Though plasticizers known as polychlorinated biphenyls, or PCBs, were banned in the U.S. in 1979, products made prior to this time still pose a risk. Phthalates, including DEHP, are found in many consumer products and medical devices manufactured from PVC/vinyl. Exposure to high doses and extended exposure have caused liver/kidney damage and liver tumors and affected reproductive development in animal studies (6). Bisphenyl A is commonly used in the production of polycarbonate plastics, including food and drink packaging and food storage containers. There are conflicting reports, but several animal studies have suggested risk to developing infants and children exposed to certain levels of BPA (5).
Researchers at Texas A&M University recently utilized a DNA aptamer discovered by Base Pair to detect low levels of DEHP in tap water, bottled mineral water, and a carbonated beverage, showing utility for environmental and food testing. Aptamer binding to DEHP in the sample resulted in a decrease of aptamer binding to functionalized particles, generating a dose-dependent change in signal. The lower limit of detection for the sensor was just 8 pM of DEHP, well below published limits of 15 – 20 nM in water. Similar sensors are being developed for other chemical contaminants (1).
Residual Herbicides, Pesticides, and Antibiotics
Weeds, pests, and disease have always been a concern for farmers. Crop farmers are increasingly turning to chemical herbicides paired with resistant crops to increase annual crop yields, but application to non-resistant crops can be devastating and residual chemicals are a growing health concern. Base Pair has discovered selective DNA aptamers for the popular herbicide Dicamba and demonstrated a lateral flow assay for field-based detection of residual herbicide. Field-based detection of herbicides and pesticides on spraying equipment can prevent unintended application and over-use. (Read more about detection of residual Dicamba at Base Pair.)
Farmers handling poultry and livestock frequently use antibiotics to preserve animal health. Unfortunately, residual antibiotics can enter the food and water supply. Researchers have utilized the ability to select aptamers to small molecules and developed aptamer-based sensors and assays for the detection of many different classes of antibiotics, including β-lactams (e.g. ampicillin), aminoglycosides (e.g. gentamicin), anthracyclines (e.g. daunomycin), (fluoro)quinolones (e.g. ofloxacin), and tetracyclines (4). Base Pair has selected aptamers to ampicilin, tetracyline, and other antibiotics. Simple, cost-effective, field-based tests will enable better monitoring and control of chemicals on the farm, at processing plants, and at food production facilities.
Identifying exposure to toxins in the environment, whether biological or man-made, is important for successful treatment. Low-level exposure is difficult to detect and identification of the specific toxin is often an even greater challenge. Researchers at Vanderbilt University and the CDC have developed a method for quantifying metabolites of two prominent nerve agents, Sarin and Venomous Agent X, using aptamers selected by Base Pair Biotechnologies. Organophosphorus nerve agents are odorless, colorless gases that affect neural communication to muscles and glands. Exposure can cause symptoms ranging from tear production and confusion to vomiting, paralysis, and even death. The team combined a free solution assay, a portable compensated interferometer, and Base Pair aptamers to selectively detect VX acid (the metabolite of Venomous Agent X) and GB acid (the metabolite of Sarin) at levels below 10 pg/mL in 25% serum (2). This type of fast, sensitive, field-based test enables both routine monitoring and rapid response.
Custom Aptamer Discovery
Base Pair has experience discovering aptamers to a wide range of chemical contaminants, including leachables from plastics (DEHP, BPA) herbicides (Dicamba), antibiotics (ampicillin, tetracycline, and others), and chemical toxins. With Base Pair’s patented multiplex SELEX, aptamers to multiple targets can be discovered in a single SELEX protocol and aptamers can be evaluated for selective detection of highly similar compounds.
Contact Base Pair today to learn more about selection of aptamers for biomarker detection.