Selection Of Aptamer For Prealbumin Protein Using SELEX And Detecting Endotoxin With The Magnetic Aptasensor

Nucleic acid aptamers are single-strand DNA or RNA molecules that bind to specific kinds of targets. Aptamers can bind to various targets such as nonorganic ions, small organic molecules, protein, and even cells, tissues. Aptamer are widely used in many areas such as life sciences research, drug screening, target detection and environmental monitoring.The way to produce aptamer is called SELEX, which is short for Systematic Evolution of Ligands by Exponential enrichment. The work includes the attempt of selecting aptamer for Prealbumin Protein using magnetic beads SELEX. Prealbumin Protein is mainly synthesized in hepatic cell. Normally, this protein is ranging from200～400mg/mL in a healthy adult’s body. However, it is altered when somebody gets liver cirrhosis. Thus prealbumin protein can be subject to a hepatopathy marker. Selection of the aptamers for prealbumin protein make it possible to create a rapid and accurate diagnosis method and an effective way to detect healing process. The process of SELEX and characterization of the aptamers selected involve many techniques including library design, PCR, single-strand DNA separation, electrophoresis and so on. After5rounds of SELEX, the experiment shows a negative consequence.Endotoxin, which is also known as lipopolysaccharide (LPS), is a marker for intruding gram-negative pathogens. It is essential to detect endotoxin quickly and sensitively in a complex milieu. A new flow cytometry (FCM)-based magnetic aptasensor assay that employs two endotoxin-binding aptamers and magnetic beads has been developed to detect endotoxin. The endotoxin-conjugated sandwich complex on magnetic beads was observed by scanning confocal laser microscopy. The resulting magnetic aptasensor rapidly detected (<1min) endotoxin within a broad dynamic detection range of10-8to100mg/ml in the presence of bovine serum albumin (BSA), RNA, sucrose and glucose, which are most likely to co-exist with endotoxin in the majority of biological liquids. Only2μl of magnetic aptasensor was required to quantify the endotoxin solution. Furthermore, the magnetic aptasensor could be regenerated seven times and still presented an outstanding response to the endotoxin solution. Therefore, the magnetic aptasensor exhibited high sensitivity, selectivity, and reproducibility, thus serving as a powerful tool for the quality control and high throughput detection of endotoxin in the food and pharmaceutical industries.