How Circular Probes Find Specific DNA in Cells

This patent describes a method using special circular DNA probes and enzymes to precisely detect specific genetic sequences within a cell or tissue sample, then amplifies the detected sequences for clear viewing.

What it covers

This method analyzes target nucleic acids, like DNA or RNA, within a cell or tissue. It uses circular probes, such as "dumbbell probes," that are designed to bind only to a specific target sequence. After the probes are introduced, an enzymatic treatment is applied. This treatment destroys any circular probes that did not bind to their target or bound incorrectly, effectively cleaning up the sample. The circular probes that successfully bound to their target nucleic acid remain intact. These intact, bound probes are then amplified using a process called rolling circle amplification (RCA), which creates many copies of the circular probe's sequence, making the target detectable. For example, a researcher could use this to find a specific viral DNA sequence inside infected cells.

What it doesn't cover

• —Does not cover methods that use linear probes instead of circular probes for target nucleic acid detection.
• —Does not cover analysis methods that do not include an enzymatic step to remove unbound or non-specifically bound probes.
• —Does not cover detection systems that do not rely on rolling circle amplification (RCA) to visualize the target.
• —Does not cover the analysis of targets other than nucleic acids, such as proteins or lipids.
• —Does not cover methods where the target nucleic acid is analyzed outside of its original cellular or tissue context (i.e., not "in situ").

The clever bit

The clever part is combining circular probes with an enzymatic step that specifically destroys only the unbound or incorrectly bound probes. This dramatically reduces background signal, ensuring that only the truly specific binding events are amplified and detected, leading to much clearer and more reliable results.

Why it matters

Precisely detecting specific nucleic acid sequences within cells or tissues is crucial for understanding diseases like cancer and infections, and for basic biological research. This method aims to improve the accuracy and clarity of such detection by reducing background noise from non-target binding. It provides a tool for scientists to visualize exactly where and how much of a particular genetic material is present in a biological sample.

Real-world examples

• 1.Detecting specific viral DNA in infected human tissue samples
• 2.Identifying gene expression patterns in cancer cells
• 3.Mapping RNA molecules within a neuron
• 4.Diagnosing bacterial infections by finding their unique DNA sequences
• 5.Studying genetic variations in individual cells