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Rapid Nucleic Acid Detection

1. Introduction

The rapid Nucleic Acid Detection Strip is Ustar's most important patented nucleic acid detection technology. It is easy-to-use, fast, sensitive, specific, and instrument-free.

Ustar' s Nucleic Acid Detection Strip can be used by itself or in a kit. When the strip is used in a kit with Ustar' s sample preparation and isothermal amplification, the entire diagnostic process is almost instrument free (only a thermal cycler and centrifuge machine are needed). These fast, easy-to-use diagnostic kits are especially helpful for onsite diagnosis (point of care testing) and testing in resource limited areas.

This strip can also works with the XCP Nucleic Acid Detection Device, which enable the detection to be contamination proof. Detection only takes a minute to prepare, and results are viewable in only 10-15 minutes.

2、Method and Mechanism

The lateral-flow immunoassays, which are exemplified by pregnancy test strips, represent a significant portion of today's immunochemical IVD market and have been widely used in clinical diagnose because of their detection speed, low cost and simplicity. These chromatographic strips employ nano-particles (20-300nm) coated with materials that bind to an analyte, such as an antibody or antigen. This analyte-nanoparticle complex flows laterally through nitrocellulose membrane until it is captured on test line of the antibody or antigen. The lateral-flow nucleic acid testing strip is based on combination of the nucleic acid hybridization and immunoassay.

If using amplification methods other than those provided by Ustar, label one of the specific primer pair with Biotin at the 5' end and the complimentary detection probe with Fitc at the 3' end (the probe must be the complimentary strand of the labeled primers). The ratio of the unlabeled primer to Biotin labeled primer should be between 1:4 and 1:10 in order to get a strong signal on the strip. Usually, the detection probe concentration only needs to be about 0.1uM. Thermal cycles should be about 40-60.

Since the probe and one of primers have been labeled with the analytes, the probe and the amplicon can form a hybridization complex when the specific amplicon is present. This complex is then captured by the antibody on the test (T) line of lateral-flow nucleic acid testing strip and detected by the colored nano-particles coated with another antibody when the complex flows laterally through nitrocellulose membrane. Otherwise, the complex can not form without the specific amplicon and the colored nano-particles would go through the test line to the top of the strip (absorbent pad). Without the colored nano-particles captured at the T line, the strip shows negative result.

The lateral-flow nucleic acid testing strip also can be made by dispensing a specific immobilized oligonucleotide (capture probe) on the T line of the nitrocellulose lateral-flow membrane. This capture probe will hybridize the target DNA sequence that can combine with the colored nano-particles.

Ten to fifteen minutes after the sample is placed on the strip, the control (C) line should appear independent of the result. However, if the color appears at the T line, the result is positive meaning that target nucleic acid has been amplified. The absence of color indicates negative result meaning the target nucleic acid has not been amplified. The DNA strip can be stored 1 year at room temperature and 2 years at 4 ℃.


C line is control line, T line is test line.

3.Product

XCP Nucleic Acid Detection Device, Cross-Contamination Proof.
Nucleic Acid Detection Device, No Cross-Contamination Proof.
Nucleic Acid Detection Strip, No Cross-Contamination Proof.

4.Patent

1) Rapid Nucleic Acid Detection on Lateral-flow Strips Application No.: 200610003429.1 (Published).
2) A Closed Nucleic Acid Detection Device, Application No.: 200610109620.4 (Accepted).