Self-Assembling Nanoparticle Conjugates

An in vitro method for detecting the presence of a target enzyme in a sample, the method comprising:

• (i) providing a composition comprising at least two nanoparticle conjugates, each nanoparticle conjugate comprising a magnetic nanoparticle;
• and at least one substrate moiety, in which each substrate moiety is linked to the nanoparticle and is chemically modified when the conjugate interacts with a target enzyme;
• wherein, when the target enzyme is absent, the nanoparticle conjugates are essentially monodisperse;
• and when the target enzyme is present, the nanoparticle conjugates self-assemble into one or more nanoparticle conjugate clusters through the formation of intermolecular linkages between the chemically modified substrate moieties;
• (ii) contacting the composition with a fluid sample;
• (iii) allowing time (a) for the target enzyme to contact the nanoparticle conjugates and (b) for the nanoparticle conjugates to self-assemble into clusters through the formation of intermolecular linkages between the chemically modified substrate moieties;
• and
• (iv) determining the spin-spin relaxation time of the fluid over time,
• wherein a decrease in spin-spin relaxation time indicates the presence of the target enzyme in the sample.

An in vivo method for detecting the presence of a target enzyme in a subject, the method comprising:

• (i) administering to the subject a composition comprising at least two nanoparticle conjugates, each nanoparticle conjugate comprising a magnetic nanoparticle;
• and at least one substrate moiety, in which each substrate moiety is linked to the nanoparticle and is chemically modified when the conjugate interacts with a target enzyme;
• wherein, when the target enzyme is absent, the nanoparticle conjugates are essentially monodisperse;
• and when the target enzyme is present, the nanoparticle conjugates self-assemble into one or more nanoparticle conjugate clusters through the formation of intermolecular linkages between the chemically modified substrate moieties;
• (ii) allowing time (a) for the target enzyme to contact the nanoparticle conjugates and (b) for the nanoparticle conjugates to self-assemble into clusters through the formation of intermolecular linkages between the chemically modified substrate moieties;
• and
• (iii) determining the spin-spin relaxation time of the fluid over time,
• wherein a decrease in spin-spin relaxation time indicates the presence of the target enzyme in the subject.

A self-assembling, nanoparticle conjugate comprising:

• a magnetic nanoparticle;
• and
• at least one substrate moiety, in which each substrate moiety is linked to the nanoparticle and is chemically modified when the conjugate interacts with a target enzyme;
• wherein,
• when two or more nanoparticle conjugates are present and when the target enzyme is absent, the nanoparticle conjugates are essentially monodisperse in a liquid;
• and
• when two or more nanoparticle conjugates are present and when the target enzyme is present, the nanoparticle conjugates self-assemble into one or more nanoparticle conjugate clusters through the formation of intermolecular linkages between the chemically modified substrate moieties.

A packaged product comprising:

• a composition comprising at least two nanoparticle conjugates, each nanoparticle conjugate comprising:
• a magnetic nanoparticle;
• and
• at least one substrate moiety, in which each substrate moiety is linked to the nanoparticle and is chemically modified when the conjugate interacts with a target enzyme;
• wherein,
• when the target enzyme is absent, the nanoparticle conjugates are essentially monodisperse in a liquid;
• and
• when the target enzyme is present, the nanoparticle conjugates self-assemble into one or more nanoparticle conjugate clusters through the formation of intermolecular linkages between the chemically modified substrate moieties.