Patent ID: 8535949

Claim:
A method of detecting an analyte in an aqueous sample for periodic or continuous remote monitoring of an analyte concentration in a subject, the method comprising: (i) providing a water relaxation sensor comprising: (a) a walled enclosure enveloping a chamber, wherein the wall comprises an opening for passage of the analyte into and out of the chamber; (b) a plurality of superparamagnetic nanoparticles located within the chamber, each superparamagnetic nanoparticle having at least one moiety that is covalently or noncovalently linked to the nanoparticle; and optionally, (c) at least one binding agent located within the chamber; wherein the opening is smaller in size than the nanoparticles, and is larger in size than the analyte; and wherein the moiety and the analyte each bind reversibly to the binding agent, when present, or the analyte binds reversibly to the moiety, to cause a reversible aggregation or disaggregation of the nanoparticles within the chamber in an equilibrium controlled process, wherein the equilibrium is dependent upon, and changes with, analyte concentration; (ii) implanting the sensor into a subject subcutaneously; and (iii) following step (ii), measuring the spin-spin (T 2 ) relaxation time of a fluid within the chamber, wherein the spin-spin (T 2 ) relaxation time measurement indicates the analyte concentration.