Abstract: A method for determining the sequence of nucleotide bases in a polynucleotide analyte is provided. It is characterised by the steps of (1) generating a stream of single nucleotide bases from the analyte; (2) producing captured molecules by reacting each single nucleotide base with a capture system; (3) amplifying at least part of the captured molecule to produce a plurality of amplicons characteristic of the single nucleotide base; (4) labelling the amplicons with a corresponding probe having a characteristic detectable element and (5) detecting a property characteristic of the detectable element.

Abstract: Disclosed is a method of identifying the contents of individual droplets in a droplet stream each droplet containing fluorophores in an initial non-fluorescing state characterized by the steps of introducing the droplets one-by-one into at least one open-ended tube to create a stack of droplets therein; activating the fluorophores within the droplets to cause them to fluoresce; releasing each droplet in the droplet stack in turn from the tube and detecting along the major axis of the tube fluorescence associated with each droplet as it emerges.

Abstract: An apparatus for sequencing a nucleic acid by printing droplets at least some of which contain single nucleotides derived from the nucleic acid is provided.

Abstract: Disclosed is a method of identifying the contents of individual droplets in a droplet stream each droplet containing fluorophores in an initial non-fluorescing state characterised by the steps of introducing the droplets one-by-one into at least one open-ended tube to create a stack of droplets therein; activating the fluorophores within the droplets to cause them to fluoresce; releasing each droplet in the droplet stack in turn from the tube and detecting along the major axis of the tube fluorescence associated with each droplet as it emerges.

Abstract: Disclosed is a method for determining the sequence of nucleotide bases in a polynucleotide analyte characterised by the steps of: a. generating a stream of droplets at least some of which contain a single nucleotide and wherein the order of single nucleotides in the droplet stream corresponds to the sequence of nucleotides in the analyte; b. introducing into each droplet a plurality of biological probe types each type (i) comprising a different detectable element in an undetectable state and (ii) being adapted to capture a different complimentary single nucleotide from which the analyte is constituted; c. causing the single nucleotide contained in the droplet to bind to its complimentary probe to create a used probe; and d. causing the detectable element to be released from the used probe in a detectable state.

Abstract: A method for determining the sequence of nucleotide bases in a polynucleotide analyte is provided. It is characterised by the steps of (1) generating a stream of single nucleotide bases from the analyte by pyrophosphorolysis; (2) producing captured molecules by reacting each single nucleotide base with a capture system labelled with detectable elements in an undetectable state; (3) releasing the detectable elements from each captured molecule in a detectable state and (4) detecting the detectable elements so released and determining the sequence of nucleotide bases therefrom. The method can be used advantageously in sequencers involving the use of microdroplets.

Abstract: A method for determining the sequence of nucleotide bases in a polynucleotide analyte is provided. It is characterised by the steps of (1) generating a stream of single nucleotide bases from the analyte by pyrophosphorolysis; (2) producing captured molecules by reacting each single nucleotide base with a capture system labelled with detectable elements in an undetectable state; (3) releasing the detectable elements from each captured molecule in a detectable state and (4) detecting the detectable elements so released and determining the sequence of nucleotide bases therefrom. The method can be used advantageously in sequencers involving the use of microdroplets.

Abstract: An apparatus for sequencing a polynucleotide analyte is provided and comprises; •a first zone in which a stream of single nucleotides is generated by progressive digestion of a molecule of the analyte attached to a particle located therein and exposed to a flowing aqueous medium; •a second zone in which a corresponding stream of aqueous droplets is generated from the aqueous medium and the nucleotide stream and wherein at least some of the droplets contain a single nucleotide and •a third zone in which each droplet is stored and/or interrogated to reveal a property characteristic of the single nucleotide it may contain; characterised in that the first zone comprises a microfluidic channel through which the aqueous medium flows and the location comprises a hollow seating in a wall thereof to which suction can be applied and into which the particle can be close-fitted.

Abstract: A method for determining the sequence of nucleotide bases in a polynucleotide analyte is provided. It is characterized by the steps of (1) generating a stream of single nucleotide bases from the analyte by pyrophosphorolysis; (2) producing captured molecules by reacting each single nucleotide base with a capture system labelled with detectable elements in an undetectable state; (3) releasing the detectable elements from each captured molecule in a detectable state and (4) detecting the detectable elements so released and determining the sequence of nucleotide bases therefrom. The method can be used advantageously in sequencers involving the use of microdroplets.

Abstract: Disclosed is a method for sequencing a polynucleotide analyte comprising: •a. generating a stream of droplets containing a single nucleotide wherein the order of single nucleotides in the droplet stream corresponds to the sequence of nucleotides in the analyte; •b. introducing into each droplet a plurality of biological probe types each type comprising a different label in an undetectable state and being adapted to capture a different single nucleotide; •c. causing the single nucleotide contained in the droplet to bind to its complementary probe and •d. causing the label to be released from the probe that has bound the nucleotide in a detectable state. The probe is a dumbbell shaped probe comprising fluorescent donor and quencher labels and a single nucleotide gap. After gap repair by a polymerase and a ligase, a restriction enzyme recognition site is cleaved by a restriction enzyme, followed by exonuclease digestion to release the labels.

Abstract: A method for determining the sequence of nucleotide bases in a polynucleotide analyte is provided. It is characterised by the steps of (1) generating a stream of single nucleotide bases from the analyte by pyrophosphorolysis; (2) producing captured molecules by reacting each single nucleotide base with a capture system labelled with detectable elements in an undetectable state; (3) releasing the detectable elements from each captured molecule in a detectable state and (4) detecting the detectable elements so released and determining the sequence of nucleotide bases therefrom. The method can be used advantageously in sequencers involving the use of microdroplets.

Abstract: A method for determining the sequence of nucleotide bases in a polynucleotide analyte is provided. It is characterised by the steps of (1) generating a stream of single nucleotide bases from the analyte; (2) producing captured molecules by reacting each single nucleotide base with a capture system; (3) amplifying at least part of the captured molecule to produce a plurality of amplicons characteristic of the single nucleotide base; (4) labelling the amplicons with a corresponding probe having a characteristic detectable element and (5) detecting a property characteristic of the detectable element.

Abstract: Disclosed is a method for determining the sequence of nucleotide bases in a polynucleotide analyte. It is characterised by analyte characterised by the steps of: a. generating a stream of droplets at least some of which comprise both (1) a single nucleotide base and (2) colloidal metal particles capable of undergoing plasmon resonance and b. irradiating each droplet with electromagnetic radiation to cause (1) the metal particles also contained therein to undergo plasmon resonance and (2) the nucleotide base contained therein to Raman scatter light at one or more wavelengths characteristic of its type. Suitably, the order of the single nucleotides bases in the droplet stream corresponds to the sequence of nucleotide bases in the analyte.

Abstract: Disclosed is a biological probe characterised in that it comprises a single-stranded nucleotide region the ends of which are attached to two different oligonucleotide regions wherein at least one of the oligonucleotide regions comprises detectable elements having a characteristic detection property and wherein the detectable elements are so arranged on the oligonucleotide region that the detectable property is less detectable than when the same number detectable elements are bound to a corresponding number of single nucleotides. The biological probe is especially useful for capturing single nucleotides or single-stranded nucleotides to create a used probe which can be degraded by means of a restriction enzyme and an exonuclease to generate single nucleotides carrying a detectable element in a form which can be detected.

Abstract: Disclosed is a method for sequencing a polynucleotide analyte comprising:•a. generating a stream of droplets containing a single nucleotide wherein the order of single nucleotides in the droplet stream corresponds to the sequence of nucleotides in the analyte;•b. introducing into each droplet a plurality of biological probe types each type comprising a different label in an undetectable state and being adapted to capture a different single nucleotide;•c. causing the single nucleotide contained in the droplet to bind to its complementary probe and•d. causing the label to be released from the probe that has bound the nucleotide in a detectable state. The probe is a dumbbell shaped probe comprising fluorescent donor and quencher labels and a single nucleotide gap. After gap repair by a polymerase and a ligase, a restriction enzyme recognition site is cleaved by a restriction enzyme, followed by exonuclease digestion to release the labels.

Abstract: Disclosed is a method for determining the sequence of nucleotide bases in a polynucleotide analyte characterised by the steps of: a. generating a stream of droplets at least some of which contain a single nucleotide and wherein the order of single nucleotides in the droplet stream corresponds to the sequence of nucleotides in the analyte; b. introducing into each droplet a plurality of biological probe types each type (i) comprising a different detectable element in an undetectable state and (ii) being adapted to capture a different complimentary single nucleotide from which the analyte is constituted; c. causing the single nucleotide contained in the droplet to bind to its complimentary probe to create a used probe and d. causing the detectable element to be released from the used probe in a detectable state.

Abstract: A device (10) for determining the number of discrete events represented by an input signal is provided. The input signal may, for example, comprise pulses representing photons arriving at a detector. The device (10) may comprise a plurality, n, of comparator circuits (14) for reading the signal. For each comparator circuit (14) from i=1 to i=n, the comparator circuit (14) has a corresponding threshold value which the amplitude of a pulse representing i discrete events will exceed, but which the amplitude of a pulse representing i-1 discrete events will not exceed. Each comparator circuit (14) is arranged to output a first value when the input signal exceeds its threshold value and a second value when the input signal is less than its threshold value. The device (10) includes a counter (16) for counting the number of outputs of the first value that have been output by the plurality of comparator circuits (14).