Provided herein is a circular proximity ligation assay in which proximity-probes are employed as bridges to connect two free oligonucleotides via a dual ligation event, resulting in the formation of a circle. The circles are then quantified by, e.g., qPCR. The addition of an extra oligonucleotide is believed to enhance specificity by decreasing the probability of random background ligation events. In addition, circle formation may have selective advantages, as uncircularized DNA can be removed by a simple exonuclease treatment and it has streamlined the workflow by eliminating preamplification prior to qPCR.

Techniques, systems, and devices are disclosed for non-thermal cycling of polymerase chain reaction (PCR). In one aspect, a method for cycling PCR includes receiving an electrolytic fluid including ions, primers, polymerase enzymes, nucleotides, and a double-stranded nucleic acid in a fluid chamber having a first electrode and a second electrode, applying an electric field across the first and the second electrodes to generate a first pH level of the electrolytic fluid to denature the double-stranded nucleic acid to at least partial single strands, and applying a second electric field across the first and second electrodes to produce a second pH level of the electrolytic fluid, in which the second pH level enables binding of a polymerase enzyme and a primer with a corresponding segment of the single strands.

Techniques, systems, and devices are disclosed for non-thermal cycling of polymerase chain reaction (PCR). In one aspect, a method for cycling PCR includes receiving an electrolytic fluid including ions, primers, polymerase enzymes, nucleotides, and a double-stranded nucleic acid in a fluid chamber having a first electrode and a second electrode, applying an electric field across the first and the second electrodes to generate a first pH level of the electrolytic fluid to denature the double-stranded nucleic acid to at least partial single strands, and applying a second electric field across the first and second electrodes to produce a second pH level of the electrolytic fluid, in which the second pH level enables binding of a polymerase enzyme and a primer with a corresponding segment of the single strands.

A method for extracting a target nucleic acid from a sample liquid includes providing a heating device having a heating element in contact with the sample liquid. The heating element is conjugated with at least one functional nucleic acid. The functional nucleic acid is adapted to hybridize to the target nucleic acid and bind the target nucleic acid to the heating element. Further, the method includes generating relative movement between the heating element and the sample liquid and extracting the target nucleic acid from the sample liquid by separating the heating element from the sample liquid.

A method for extracting a target nucleic acid from a sample liquid includes providing a heating device having a heating element in contact with the sample liquid. The heating element is conjugated with at least one functional nucleic acid. The functional nucleic acid is adapted to hybridize to the target nucleic acid and bind the target nucleic acid to the heating element. Further, the method includes generating relative movement between the heating element and the sample liquid and extracting the target nucleic acid from the sample liquid by separating the heating element from the sample liquid.

A method for determining the presence, absence or amount of two or more target polynucleotides in a sample comprising additional components, the method comprising: (i) contacting the sample with a panel of two or more probes under conditions suitable for hybridisation of the target polynucleotides to the probes, wherein: (a) each probe comprises a non-hybridisation region and a hybridisation region that specifically hybridises to one of the target polynucleotides to form a hybridised probe; and (b) the hybridisation region of a probe of the panel comprises one or more non-natural nucleotides; (ii) contacting the sample prepared in step (i) with a transmembrane pore through which a single stranded polynucleotide but not a double stranded polynucleotide can pass and applying a potential difference to the transmembrane pore such that the hybridised probes in the sample interact with the pore; (iii) measuring current blockades having a duration within a defined window, wherein: (a) the one or more non-natural nucleotides present in the hybridisation region of the probe increase or decrease the duration of the current blockade due to the probe hybridised to its target polynucleotide such that the proportion of current blockades that occur within the window due to the interaction of the hybridised probes with the pore is increased compared to when the corresponding one or more natural nucleotides are present in the hybridisation region; and (b) each hybridised probe gives rise to a current blockade indicative of that probe; and (iv) correlating the measured current blockades with the probes, thereby determining the presence, absence or amount of the two or more target polynucleotides in the sample.

A method for determining the presence, absence or amount of two or more target polynucleotides in a sample comprising additional components, the method comprising: (i) contacting the sample with a panel of two or more probes under conditions suitable for hybridisation of the target polynucleotides to the probes, wherein: (a) each probe comprises a non-hybridisation region and a hybridisation region that specifically hybridises to one of the target polynucleotides to form a hybridised probe; and (b) the hybridisation region of a probe of the panel comprises one or more non-natural nucleotides; (ii) contacting the sample prepared in step (i) with a transmembrane pore through which a single stranded polynucleotide but not a double stranded polynucleotide can pass and applying a potential difference to the transmembrane pore such that the hybridised probes in the sample interact with the pore; (iii) measuring current blockades having a duration within a defined window, wherein: (a) the one or more non-natural nucleotides present in the hybridisation region of the probe increase or decrease the duration of the current blockade due to the probe hybridised to its target polynucleotide such that the proportion of current blockades that occur within the window due to the interaction of the hybridised probes with the pore is increased compared to when the corresponding one or more natural nucleotides are present in the hybridisation region; and (b) each hybridised probe gives rise to a current blockade indicative of that probe; and (iv) correlating the measured current blockades with the probes, thereby determining the presence, absence or amount of the two or more target polynucleotides in the sample.

Methods and apparatuses to non-destructively and periodically sample a small quantity of intracellular proteins and mRNA from the same single cell or cells for an extended period of time. Specifically, describe herein are non-perturbative methods for time-resolved, longitudinal extraction and quantitative measurement of intracellular proteins and nucleic acids from a variety of cell types using systems including nanostraws.

Methods and apparatuses to non-destructively and periodically sample a small quantity of intracellular proteins and mRNA from the same single cell or cells for an extended period of time. Specifically, describe herein are non-perturbative methods for time-resolved, longitudinal extraction and quantitative measurement of intracellular proteins and nucleic acids from a variety of cell types using systems including nanostraws.

Devices and methods that can detect and control an individual polymer in a mixture is acted upon by another compound, for example, an enzyme, in a nanopore are provided. The devices and methods also determine (˜>50 Hz) the nucleotide base sequence of a polynucleotide under feedback control or using signals generated by the interactions between the polynucleotide and the nanopore. The invention is of particular use in the fields of molecular biology, structural biology, cell biology, molecular switches, molecular circuits, and molecular computational devices, and the manufacture thereof.