Bioresponsive Particles

Abstract

Shielding enzymes are made by modifying the enzyme surface with silica precursors and then depositing silica to a desired thickness while retaining biological activity of the enzyme.

What is claimed is: 
     
         1 . A method of making a silica-modified enzyme, comprising the steps of:
 a) reacting an acrylic compound (acryloyl derivative) with amine groups of an enzyme to covalently decorate the enzyme with enone groups; and   b) coupling a silyl amine to the enone groups to covalently decorate the enzyme with silyl groups, forming a silica-modified enzyme.   
     
     
         2 . The method of  claim 1  wherein the acrylic compound comprises an acryloyl group and a N-hydroxysuccinimide group, such as N-acryloxysuccinimide or acrylate-polyethyleneglycol N-hydroxysuccinimide. 
     
     
         3 . The method of  claim 1  wherein the silyl amine is comprises a silyl ether group and an amine group, such as 3-aminopropyl trimethoxysilane (APTMS) or 3-aminopropyl triethoxysilane (APTES). 
     
     
         4 . The method of  claim 2  wherein the silyl amine is comprises a silyl ether group and an amine group, such as 3-aminopropyl trimethoxysilane (APTMS) or 3-aminopropyl triethoxysilane (APTES). 
     
     
         5 . The method of  claim 1  wherein the enzyme is selected from catalase, superoxide dismutase, asparaginase, methioninase, carboxypeptidase G2 and luciferase. 
     
     
         6 . The method of  claim 4  wherein the enzyme is selected from catalase, superoxide dismutase, asparaginase, methioninase, carboxypeptidase G2 and luciferase. 
     
     
         7 . A method of making hybrid enzyme-silica nanoparticles (HES-NPs) using a silica-modified enzyme synthesizable by the method of  claim 1 , comprising the steps of:
 i) growing a siloxane scaffold around the silica-modified enzyme, wherein the silyl groups seed the growth of the siloxane scaffold (e.g., in an emulsion or aqueous medium) to form hybrid enzyme-silica nanoparticles (HES-NPs); and   ii) isolating (e.g. from the emulsion or medium) the hybrid enzyme-silica nanoparticles.   
     
     
         8 . The method of  claim 7  wherein step (i) comprises contacting the silica-modified enzyme with tetraethoxysilane under surfactant-free aqueous conditions and hydrolyzing (e.g. with ammonium hydroxide) silane groups to start the growth of the siloxane scaffold. 
     
     
         9 . The method of  claim 7  wherein step (i) comprises contacting the silica-modified enzyme with tetraethoxysilane under reverse emulsion conditions and hydrolyzing silane groups to start the growth of the siloxane scaffold. 
     
     
         10 . The method of  claim 7  further comprising the antecedent steps of:
 a) reacting an acrylic compound (acryloyl derivative) with amine groups of an enzyme to covalently decorate the enzyme with enone groups; and 
 b) coupling a silyl amine to the enone groups to covalently decorate the enzyme with silyl groups, forming a silica-modified enzyme. 
 
     
     
         11 . The method of  claim 10  wherein:
 the acrylic compound comprises an acryloyl group and a N-hydroxysuccinimide group, such as N-acryloxysuccinimide or acrylate-polyethyleneglycol N-hydroxysuccinimide; and 
 the silyl amine is comprises a silyl ether group and an amine group, such as 3-aminopropyl trimethoxysilane (APTMS) or 3-aminopropyl triethoxysilane (APTES). 
 
     
     
         12 . The method of  claim 7  wherein the enzyme is selected from catalase, superoxide dismutase, asparaginase, methioninase, carboxypeptidase G2 and luciferase. 
     
     
         13 . The method of  claim 11  wherein the enzyme is selected from catalase, superoxide dismutase, asparaginase, methioninase, carboxypeptidase G2 and luciferase. 
     
     
         14 . The method of  claim 7  wherein the nanoparticles are of average size 20-100 nm or 20-50 nm diameter. 
     
     
         15 . The method of  claim 7  further comprising the step of administering the nanoparticles to a person in need thereof. 
     
     
         16 . The method of  claim 7  further comprising the steps of administering the nanoparticles to a person in need thereof, the enzyme is catalase. 
     
     
         17 . The method of  claim 7  further comprising the step of administering the nanoparticles to a person in need thereof, wherein the nanoparticles provide a bioresponsive ultrasound contrast agent, and imaging the patient by ultrasound, such as wherein the enzyme is catalase, effective to generate O 2  bubbles. 
     
     
         18 . The method of  claim 7  further comprising the step of administering the nanoparticles to a person in need thereof, wherein the person has or is at (imminent, demonstrable) risk of reperfusion injury and the enzyme is catalase, effective to scavenge reactive oxygen species (ROS). 
     
     
         19 . The method of  claim 7  further comprising the step of administering the nanoparticles to a person in need thereof, wherein the person has leukemia (e.g. acute lymphoblastic leukemia, ALL) and the enzyme is asparaginase, effective to deplete asparagine. 
     
     
         20 . The method of  claim 7  further comprising the step of administering the nanoparticles to a person in need thereof, wherein the person is, has been or will be administered a prodrug, and the enzyme is prodrug converting enzyme, effective to convert the prodrug to a therapeutic drug.