Surface-activation of semiconductor nanostructures for biological applications

Abstract

The present invention provides means and methods for producing surface-activated semiconductor nanoparticles suitable for in vitro and in vivo applications that can fluoresce in response to light excitation. Semiconductor nanostructures can be produced by generating a porous layer in semiconductor substrate comprising a network of nanostructures. Prior or subsequent to cleavage from the substrate, the nanostructures can be activated by an activation means such as exposing their surfaces to a plasma, oxidation or ion implantation. In some embodiments, the surface activation renders the nanostructures more hydrophilic, thereby facilitating functionalization of the nanoparticles for either in vitro or in vivo use.

What is claimed is: 
     
         1 .- 38 . (canceled) 
     
     
         39 . A nanoparticle suspension, comprising:
 an aqueous medium, and   a plurality of semiconductor nanoparticles having dimensions in a range of about 1 nm to about 500 nm dispersed in said aqueous medium so as to form a suspension,   wherein said semiconductor nanoparticles comprise activated surfaces for enhacing hydrophilicity thereof.   
     
     
         40 . The nanoparticle suspension of  claim 39 , wherein said activated surfaces comprise an oxide layer. 
     
     
         41 . The nanoparticle suspension of  claim 39 , wherein said activated surfaces comprise a plurality of implanted ions at a concentration in a range of about 10 12  to 10 17  ions/cm 2 . 
     
     
         42 . The nanoparticle suspension of  claim 39 , wherein said activated surfaces are generated by exposure of the semiconductor nanoparticles to a plasma. 
     
     
         43 . The nanoparticle suspension of  claim 39 , further comprising a plurality of ligands attached to said activated surfaces. 
     
     
         44 . The nanoparticle suspension of  claim 39 , wherein said ligands are attached to the activated surfaces via any of covalent, non-covalent, ion, and metallic bonds. 
     
     
         45 . The nanoparticle suspension of  claim 39 , wherein said ligands are attached to the activated surfaces via van der Waals interactions. 
     
     
         46 . The nanoparticle suspension of  claim 39 , wherein said ligands are attached to the activated surfaces via any of cross-linking and caging. 
     
     
         47 . The nanoparticle suspension of  claim 39 , wherein a density of said nanoparticles in said suspension is in a range of about 1 microgram to about 10 milligrams per milliliter. 
     
     
         48 . The nanoparticle suspension of  claim 39 , wherein a density of said nanoparticles in the suspension is in a range of about 10 to 20 microMolar. 
     
     
         49 . The nanoparticle suspension of  claim 39 , wherein said nanoparticles comprise any of silicon, germanium, arsenic, Group II-VI, Group III-V semiconductors or a combination thereof. 
     
     
         50 . The nanoparticle suspension of  claim 39 , wherein said nanoparticles include any of p-type and n-type dopants. 
     
     
         51 . The nanoparticle suspension of  claim 39 , wherein the plurality of semiconductor nanoparticles have a dimension in a range of about 5 nm to about 200 nm. 
     
     
         52 . The nanoparticle suspension of  claim 39 , wherein the plurality of semiconductor nanoparticles have a dimension in a range of about 2 nm to about 10 nm. 
     
     
         53 . The nanoparticle suspension of  claim 39 , wherein the plurality of semiconductor nanoparticles have a dimension in a range of about 0.5 nm to about 25 nm. 
     
     
         54 . A colloidal suspension, comprising:
 a medium, and   a plurality of fluorescent semiconductor nanoparticles dispersed in said medium, said nanoparticles having activated surfaces for enhancing colloidal stability and having a dimension in a range of about 1 nm to about 500 nm,   wherein said nanoparticles retain their fluorescent properties in said medium.   
     
     
         55 . The colloidal suspension of  claim 54 , wherein said medium is water based and said activated surfaces enhance hydrophilicity of said nanoparticles. 
     
     
         56 . The colloidal suspension of  claim 54 , wherein said activated surfaces enhance hydrophobicity of said nanoparticles. 
     
     
         57 . The colloidal suspension of  claim 54 , wherein said activated surfaces comprise any of an oxide layer and a plurality of implanted ions at a concentration in a range of about 10 12  to 10 17  ions/cm 2 . 
     
     
         58 . The colloidal suspension of  claim 54 , wherein said activated surfaces are generated by exposure of the semiconductor nanoparticles to a plasma. 
     
     
         59 . The colloidal suspension of  claim 54 , wherein a density of said nanoparticles in the colloidal suspension is in a range of about 1 microgram to about 10 milligrams per milliliter. 
     
     
         60 . The colloidal suspension of  claim 54 , wherein the plurality of semiconductor nanoparticles have a dimension in a range of about 5 nm to about 200 nm.