Diagnostic methods and devices

A method for detecting the presence or absence of a target nucleic acid in a test sample, comprising the steps of:

• i) heat denaturation of a test sample;
• optionally, ii) providing and contacting an excess of an oligonucleotide blocking probe capable of specific binding to the antisense strand of a target nucleic acid with the test sample under conditions suitable for the binding of the blocking probes to the antisense strand of the target nucleic acid, thereby preventing the reannealing of sense and antisense strands of the target nucleic acid;
• iii) providing a plurality of detector nanoparticles functionalised with a first probe specific for a first region of the sense strand of a target nucleic acid and a second probe specific for a second region of the sense strand of the target nucleic acid;
• iv) contacting said detector nanoparticles with the test sample under conditions suitable for the binding of the specific probes to the target nucleic acid, wherein the presence of the target nucleic acid in the test sample results in agglomeration of the detector nanoparticles;
• v) irradiating the detector nanoparticles with a source of electromagnetic radiation configured to provide energy at the resonant wavelength of the detector nanoparticles when in an agglomerated state, thereby directing a heat transfer sufficient to cause at least partial thermal breakdown of a plurality of thermoresponsive microspheres containing a signal means;
• and
• vi) observing the release or lack thereof of the signal means from the microspheres, wherein the released signal means is captured for detection on a retention strip observable with the naked eye.

A device for detecting the presence or absence of a target nucleic acid in a test sample, comprising:

• i) a sample inlet;
• ii) a lysis compartment in communication with the sample inlet, said lysis compartment comprising a heating element;
• iii) a detection compartment, having:
• a plurality of detector nanoparticles functionalised with a first probe specific for a first region of the sense strand of a target nucleic acid and a second probe specific for a second region of said target nucleic acid and optionally an excess of a blocking probe capable of specific binding to the antisense strand of a target nucleic acid;
• iv) an integrated source of electromagnetic radiation configured to provide energy at the resonant wavelength of the detector nanoparticles in an agglomerated state;
• v) a plurality of thermoresponsive microspheres having a core comprising signal means and a shell enclosing the core, wherein the shell comprises a thermoresponsive polymer;
• and
• vi) a signal display region in communication with the detection compartment, said signal display region comprising a retention strip to capture the signal means following release from the thermoresponsive microspheres.

A kit comprising:

• i) a device having:
• a sample inlet;
• a lysis compartment comprising a heating element;
• an integrated source of electromagnetic radiation;
• a plurality of thermoresponsive microspheres having a core comprising signal means and a shell enclosing the core, wherein the shell comprises a thermoresponsive polymer;
• and
• a signal display region comprising a retention strip to capture the signal means following release from the microspheres;
• optionally, ii) one or more populations of a blocking probe capable of specific binding to the antisense strand of a target nucleic acid;
• and
• iii) one or more populations of a plurality of detector nanoparticles functionalised with a first probe specific for a first region of the sense strand of said target nucleic acid and a second probe specific for a second region of said target nucleic acid.