Water-soluble silsesquioxanes as organic quantum dots for sensing and imaging

A compound represented by the following structural formula:

• or an acceptable salt thereof, wherein:
• each A is a group independently selected from the following structural formulae:
• Ar is an optionally substituted aromatic group;
• Linker is a single bond, double bond, triple bond, —CR1m—;
• wherein R1 is hydrogen, a halogen, a hydroxy group, an amino group, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, or a C1-C6 alkoxy group;
• wherein the alkyl, alkenyl, alkynyl, or alkoxy groups may be optionally substituted with a halogen, a hydroxy group, a C1-C4 alkoxy goup, or an amino group, wherein m is 1 or 2;
• and
• each R is independently hydrogen, a cationic alkyl side group, a cationic oligo(ethylene oxide) group or a cationic poly(ethylene oxide) group, provided that at least one R is not hydrdogen.

A compound represented by the following structural formula:

• or an acceptable salt thereof, wherein:
• each A is a group independently selected from the following structural formulae:
• Ar is an optionally substituted aromatic group;
• each Linker is a single bond, double bond, triple bond, —CH2—, or —CH2CH2—;
• and
• each R is independently hydrogen, a cationic alkyl side group, a cationic oligo(ethylene oxide) group, or a cationic poly(ethylene oxide) group, provided that at least one R is not hydrogen.

A method of imaging the nucleus in a cell, comprising the steps of:

• exposing the cell to a polyhedral oligomeric silsesquioxane compound comprising a polycyclic compound consisting of a silicon/oxygen cage surrounded by tunable organic substitution groups attached to silicon atoms of the silicon/oxygen cage;
• (i) wherein the tunable organic substitution groups are independently selected from the following structural formulae:
• Ar is an optionally substituted aromatic group;
• Linker is a single bond, double bond, triple bond, or —CR1m;
• wherein R1 is hydrogen, a halogen, a hydroxy group, an amino group, a C1-C6 alkyl group, a C2-C6alkenylgroup, a alkynyl group, or a C1-C6 alkoxy group;
• wherein the alkyl, alkenyl, alkynyl, or alkoxy groups may be optionally substituted with a halogen, a hydroxy group, a C1-C4 alkoxy group, or an amino group;
• and
• each R is independently hydrogen, a cationic alkyl side group, a cationic oligo(ethylene oxide) group, or a cationic poly(ethylene oxide) group, provided that at least one R is not hydrogen;
• or
• (ii) wherein the tunable organic substitution groups are independently selected from the following structural formulae:
• each
• is independently selected from:
• each Ar is independently an optionally substituted aromatic group;
• each R is independently a cationic or anionic alkyl group, or a cationic or anionic oligo(ethylene oxide) group, or a cationic or anionic poly(ethylene oxide) group;
• each Linker is a single bond, double bond, triple bond, —CH2—, or —CH2CH2—;
• and
• each R′ is independently H or a terminal reactive group;
• allowing the polyhedral oligomeric silsesquioxane compound to bind to the nucleus;
• and
• assaying the cell to determine the location of the polyhedral oligomeric silsequioxane Compound within or on the cell.

A method of quantifying a biomolecule, comprising the steps of:

• exposing the biomolecule to a polyhedral oligomeric silsesquioxane compound comprising a polycyclic compound consisting of a silicon/oxygen cage surrounded by tunable organic substitution groups, attached to silicon atoms of the silicon/oxygen cage;
• (i) wherein the tunable organic substitution groups are independently selected from the following structural formulae:
• Ar is an optionally substituted aromatic group;
• Linker is a single bond, double bond, triple bond, or —CR1m—;
• wherein R1 is hydrogen, a halogen, a hydroxy group, an amino group, a C1-C6 alkyl group, a C2-C6 alkenylgroup, a C2-C6 alkynyl group, or a C1-C6 alkoxy group;
• wherein the alkyl, alkenyl, alkynyl, or alkoxy groups may be optionally substituted with a halogen, a hydroxy group, a C1-C4 alkoxy group, or an amino group;
• and
• each R is independently hydrogen, a cationic alkyl side group, a cationic oligo(ethylene oxide) group, or a cationic poly(ethylene oxide) group, provided that at least one R is not hydrogen;
• or
• (ii) wherein the tunable organic substitution groups are independently selected from the following structural formulae:
• each
• is independently selected from:
• each Ar is independently an optionally substituted aromatic group;
• each R is independently a cationic or anionic alkyl group, or a cationic or anionic oligo(ethylene oxide) group, or a cationic or anionic poly(ethylene oxide) group;
• each Linker is a single bond, double bond, triple bond, —CH2—, or —CH2CH2—;
• and
• each R′ is independently H or a terminal reactive group;
• allowing the polyhedral oligomeric silsesquioxane compound to bind to the biomolecule;
• and assaying the polyhedral oligomeric silsesquioxane compound, thereby quantifying the biomolecule.

A method to detect a biological molecule in a test solution, comprising the steps of:

• providing an aptamer capable of binding the biological molecule;
• immobilizing the aptamer on a solid support;
• incubating the immobilized aptamer with the test solution;
• exposing the test solution to a polyhedral oligomeric silsesquioxane compound comprising a polycyclic compound consisting of a silicon/oxygen cage surrounded by tunable organic substitution groups, attached to silicon atoms of the silicon/oxygen cage;
• (i) wherein the tunable organic substitution groups are independently selected from the following structural formulae:
• Ar is an optionally substituted aromatic group;
• each Linker is a single bond, double bond, triple bond, —CH2—or —CH2CH2—;
• and
• each R is independently hydrogen, a cationic alkyl side group, a cationic oligo(ethylene oxide) group, or a cationic poly(ethylene oxide) group, provided that at least one R is not hydrogen;
• or
• (ii) wherein the tunable organic substitution groups are independently selected from the following structural formulae:
• each
• is independently selected from:
• each Ar is independently an optionally substituted aromatic group;
• each R is independently a cationic or anionic alkyl group, or a cationic or anionic oligo(ethylene oxide) group, or a cationic or anionic poly(ethylene oxide) group;
• each Linker is a single bond, double bond, triple bond, —CH2—or —CH2CH2—;
• and
• each R′ is independently H or a terminal reactive group;
• and measuring the fluorescence of the test solution, thereby detecting the biological molecule.