Biomolecular Sensors for Optical Nucleic Acid Detection

Optical nucleic acid detection sensors are biosensors that use a molecular recognition element that specifically binds to a substrate to produce a characteristic optical signal (e.g., fluorescence, color change) that can be output and thus used to analyze the substance to be tested. For plant pathogen detection, Lifeasible offers you gold nanoparticles (AuNPs) based colorimetric assays (e.g., lateral flow immunoassays, LFIAs) as well as fluorescence and colorimetric microarray and electrochemiluminescence (ECL) based assays.

LFIAs

LFIAs are paper-based biosensors for real-time monitoring, known as immunochromatographic test strips. We use the principle of immunochromatography to flow the test sample through the matrix by capillary action, which causes antigen and antibody to bind, thus allowing these complexes to be detected and visualized. AuNPs have good optical properties and biocompatibility, so we often use AuNPs as a material for signal transduction in colorimetric sensors.

• Acidovorax avenae subsp. Citrulli (AAC) detection
  We use AuNP-labelled oligonucleotide probes as indicators for AAC detection. The method is based on competitive hybridization of the target DNA with the DNA probe on the detection line to achieve detection of the target DNA. The more target DNA in the detection solution, the higher the probability that the probe is immobilized on the AuNPs to form dsDNA with the target DNA. Qualitative detection is achieved by colorimetric changes in the detection line, and semi-quantitative detection is achieved by optical density analysis software.
• Banana bunchy top virus (BBTV) detection
  We achieved target capture using a small lateral flow detection platform and hybridizing AuNPs colorimetric probes, with AuNPs-DNA as the detection probe and biotin-labeled DNA as the capture probe. The colorimetric probes captured on the detection and control lines of the gene sensor produce characteristic red bands, allowing visual detection of amplification products within minutes. The method enables quantitative analysis by recording the light intensity of the test line and can be used for BBTV identification.

ECL

ECL is a method of converting electrical energy into radiant energy. By applying a voltage or current signal of a certain waveform to an electrode for an electrolytic reaction, active intermediates are produced from stable precursors on the electrode surface. These intermediates react with coexisting components of the system to form excited states and emit light.

• We can utilize a modified ECL-PCR assay as a diagnostic method for plant virology. This method takes advantage of the high affinity of biotin-streptavidin. It uses magnetic beads as a tool for the isolation of hybridization products. At the same time, three plant viruses, banana streak virus (BSV), BBTV, and papaya leaf curl virus (PLCV), were amplified by PCR and hybridized with TBR-labelled probes and a biotin-labeled capture probes. We captured the hybridization products on streptavidin-coated magnetic beads and used TPA as a co-reactor to generate the ECL signal of TBR. We reduced the detection limit of PCR products to 50 fmol/L by stabilizing the ECL signal.

Lifeasible offers gold nanoparticle-based colorimetric and electrochemiluminescent assays for various plant pathogens such as AAC, BBTV, BSV, PLCV, etc., with low detection limits. Please feel free to contact us with information on the plant pathogens you would like to test for so that we can provide you with a tailored test protocol.