Guanine invented the electrical oligonucleotide detection tag

Guanine’s oligonucleotide tags produce an electrical current that can be measured with a biosensor and potentiostat.  The tags bind to target analytes and produce an electrical current peak that is proportional to the quantity of analytes in the sample.

• Oligonucleotide tags generate a burst of electrons when voltage is applied
  
• The burst is bigger when tags comprise a 20-mer polyGuanine sequence that is prefabricated into quadruplexes (planes of 4 guanine separated by Na+ cations) that generate 8-oxoguanine oxidation peaks
• The electrical signal is amplified when millions of quadruplexes are fabricated onto a microparticle with ligands then bind to nucleic acid targets, antigens, antibodies or toxins
  

SIGNAL-AMPLIFIED IMMUNOASSAY AND
SIGNAL-AMPLIFIED HYBRIDIZATION ASSAY

Quadruplex tags are used in sandwich assays. A single optical label is replaced with a microparticle delivering millions of electrical quadruplex tags per analyte for proteins or nucleic acids. Quadruplexes and capture ligands are conjugated to a microparticle to deliver millions of tags per analyte. The larger the microparticle, the greater the number of tags per analyte and bigger electrical current peak. Magnetic microparticles are used to increase the detection signal-to-noise ratio by magnetically separating bound analytes from nonspecific materials that cause noise and false detection outcomes. Magnetic microparticle-analyte conjugates bind to sensor electrodes with recognition ligands to form sandwiches. A voltammetry scan generates an oxidation peak proportional to analyte concentration. Multiplexing is done using sensor with multiple electrodes. A cocktail of multiple magnetic microparticles bind analytes that can be detected individually or in a group for detecting a range of analytes.

Square Wave Voltammetry (SWV) generates current signals from magnetic microparticle-target sandwiches in a sample from 8-oxoguanine plus NaOAc, and a background signal from a calibration scan of NaOAc on the same electrode (Fig. A) The net peak signal from 8-oxoguanine less the background signal around 0.47 V (Fig. B) is used to determine if the target is present in the sample when the peak electrical current from the sample exceeds the peak electrical current at a negative control electrode plus 3 standard deviations. Results from a Guanine assay illustrate a positive signal (2.0 µA) from a KPC-producing K. pneumoniae sample and a negative signal from a non KPC-producing K. pneumoniae (Fig. C), assay performance of 22/22 True Positives and 1/6 False Positives (Fig. D), and relative net signal from different microparticle sizes (Fig. E).

RAPID, SIMPLE AND INEXPENSIVE DETECTION

Guanine’s configurable test cartridge comprises an insert chamber for fluids or swabs (1) that allows the sample to be mixed with prepared lysis buffer (2). After incubation magnetic particle conjugates (3) are added to the mixing chamber to capture analytes then a magnetic field is applied. Waste material is drained to a waste reservoir (5) and conjugate-analyte complexes are washed with detection buffer (4). After the drain is closed and magnetic field is removed, detection buffer (4) is added to resuspend the magnetic particle-target complexes and flow the complexes to the sensor (6) for binding with the complementary electrode ligand. Detection buffer is added to the sensor chamber to wash away unbound materials and fill the chamber with electrolyte. A potentiostat connects to the sensor connectors and applies a voltammetry scan on each electrode to generate 8-oxoguaine oxidation current peaks from the targets on each electrode. Results can be displayed and transmitted to the cloud or databases.

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ARTIFICIAL INTELLIGENCE PLATFORM TO DIAGNOSE DISEASE

Guanine's patent-pending detection and AI diagnosis platform for difficult-to-diagnose diseases can be used to combine information about low concentration protein and nucleic acid biomarkers in body fluids, along with symptoms, image recognition of skin lesions at different points in time, and other information as input data. The algorithm can then apply a series of modules to assess what information is needed for a diagnosis, diagnose the disease based on current guidelines, and ultimately learn new links between the data and diagnosis by assessing multiple types of data during disease progression from a wide population of patients. The tool is intended for individuals who believe that they may be infected but have not decided to see a doctor. If warranted, the tool will recommend the urgency of going to a doctor and provide the rationale that supports the recommendation. The tool can also explain if the symptoms are not likely to be a disease at the current time and invite the individual to update their information if symptoms change. The tool will also generate a report for the doctor highlighting pertinent factors that can reduce the time that the doctor needs for assessment. The tool will also provide a preliminary differential diagnosis as an objective second opinion that can confirm the doctor’s diagnosis or offer an alternative that the doctor did not consider.

PATENTS

Bioanalyte signal amplification and detection with artificial intelligence diagnosis.
Gordon, N. United States Patent and Trademark Office, US 2019/0079084 A1 (2019)  EP, CA
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Ultra-sensitive bioanalyte quantification from self-assembled quadruplex tags.
Gordon, N.United States Patent and Trademark Office, US 2018/0106791 A1 (2018)  CA
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Ultra-sensitive detection of extremely low level biological analytes using electrochemical signal amplification and biosensor.
Gordon, N. United States Patent and Trademark Office, US 9,624,532 B2 (2017) CA, DE, FR, GB
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PUBLICATIONS

Carbapenem-Resistant Enterobacteriaceae Testing in 45 Minutes using an Electronic Sensor
Gordon, N., Bawa, R., Palmateer, G., Rajabi, M., Gordon J.B., Kotb, N.M., Balasubramaniyam, R, Gordon, B.R. Advances in Therapeutics, Diagnostics and Applications. Volume 4, Chapter 1, Jenny Stanford Publishers, Singapore (2021) (in press)  
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Universal Bioanalyte Signal Amplification for Electrochemical Biosensor
Gordon, N. Biosensors J 5: 135 (2016)
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Highly Sensitive Bacteria Quantification Using Immunomagnetic Separation and Electrochemical Detection of Guanine-Labeled Secondary Beads
Jayamohan, H. Gale, B.K,. Minson, B.J., Lambert, C.J., Gordon, N., Sant, H.J. Sensors, 15, 12034–12052 (2015).
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