Functionalized nanoparticles and methods of making and using same
Described is a versatile surface modification approach to, for example, modularly and orthogonally functionalize nanoparticles (NPs) such as, for example, PEGylated nanoparticles, ith various types of different functional ligands (functional groups) on the NP surface. It enables the synthesis of, for example, penta-functional PEGylated nanoparticles integrating a variety of properties into a single NP, e.g., fluorescence detection, specific cell targeting, radioisotope chelating/labeling, ratiometric pH sensing, and drug delivery, while the overall NP size remains, for example, below 10 nm.
1. A method of forming a functionalized PEGylated silica nanoparticle comprising:
functionalizing a silica nanoparticle using a post PEGylation surface modification by insertion (PPSMI) step, wherein the nanoparticle has a diameter of 2 to 15 nm and comprises a plurality of polyethylene glycol (PEG) groups covalently bound to the surface of the nanoparticle,
wherein the PPSMI step comprises inserting a functionalizing precursor between PEG groups on the nanoparticle and covalently binding the precursor to the surface of the nanoparticle, wherein the functionalizing precursor comprises a silane group and a reactive group, and wherein the PPSMI step is carried out in an aqueous reaction medium,
thereby forming a functionalized PEGylated silica nanoparticle comprising a reactive group covalently bound to the surface of the nanoparticle.
2. The method of claim 1 , further comprising inserting one more additional functionalizing precursors between PEG groups on the nanoparticle and covalently binding the one or more additional precursors to the surface of the nanoparticle, wherein the one or more additional precursors each comprise a silane group and a reactive group.
3. The method of claim 2 , wherein each additional functionalizing precursor is inserted in the same reaction mixture.
4. The method of claim 2 , wherein the inserting for an additional functionalizing precursor is carried out in a separate reaction mixture.
5. The method of claim 1 , wherein the reactive group is chosen from an amine group, a thiol group, a carboxylic acid group, a carboxylate group, an ester group, a maleimide group, an allyl group, a terminal alkyne group, an azide group, a thiocyanate group, and combinations thereof.
6. The method of claim 1 , wherein the silane group is:
wherein R is, independently at each occurrence, a C 1 to C 4 alkyl group, and
R′ is H or a C 1 to C 4 alkyl group.
7. The method of claim 1 , wherein the functionalizing precursor has the following structure:
wherein X is a an amine group, a thiol group, a carboxylic acid group, a carboxylate group, an ester group, a maleimide group, an allyl group, a terminal alkyne group, an azide group, or a thiocyanate group,
n is 1 to 8, and
R is, independently at each occurrence, a C 1 to C 4 alkyl group.
8. The method of claim 1 , wherein the nanoparticle is a core-shell silica nanoparticle.
9. The method of claim 1 , wherein the nanoparticle has a diameter of 2 to 10 nm.
10. The method of claim 1 , further comprising a step of reacting the reactive group covalently bound to the surface of the nanoparticle with a functional group precursor.
11. The method of claim 10 , wherein the functional group precursor comprises a dye, a chelator, a targeting group, or a drug.
12. The method of claim 11 , wherein the drug comprises a chemotherapeutic agent.
13. The method of claim 11 , wherein the targeting group has a specific binding affinity to tumor cells.
14. The method of claim 11 , wherein the targeting group comprises a linear or cyclic peptide, or an antibody fragment.
15. The method of claim 10 , wherein the functional group precursor comprises a maleimide group, an NHS ester group, an azide group, an amine group, a thiol group, or an alkyne group.
16. The method of claim 1 , wherein the aqueous reaction medium does not contain organic solvents other than polar aprotic solvents at 10% or greater.
17. The method of claim 1 , wherein the nanoparticle comprises one or more fluorescent dye molecules encapsulated therein.
18. The method of claim 17 , wherein the fluorescent dye molecule is Cy5 or Cy5.5.
19. The method of claim 10 , wherein the reacting comprises click chemistry.