Methods for Producing Semiconductor Nanoparticles

Abstract

New semiconductor nanoparticles and manufacturing technologies, including novel methods, systems, and compositions, are provided herein. Robust, reproducible production of large amounts of semiconductor nanoparticles, such as quantum dots, from bacterial cultures during continuous growth is provided, without a need for extensive post growth processing or modification. The result is a novel semiconductor of nanoparticle dimensions and quality that is suitable for commercial applications in lighting, display, imaging, diagnostics, photovoltaics and hydrogen generation, for example. In one embodiment, bacterial-based synthesis methods for producing nanocrystal semiconductor quantum dots are provided by aqueous, environmentally friendly media and methods.

1 - 26 . (canceled) 
     
     
         27 . A biosynthetic method of making semiconductor quantum dots (sQDs) comprising:
 providing a selected bacterial strain that is adapted for tolerance to cadmium and producing sQDs when grown in a growth culture medium comprising;   placing the selected bacterial strain in an aerobic fluid culture and inducing production of controlled size sQDs by growing the selected bacterial strain in the growth culture medium comprising cadmium for a time sufficient for the selected bacterial strain to utilize the cadmium to assemble sQDs and extracellularly release the sQDs into the growth culture medium; and   harvesting the sQDs from a cell-free supernatant of the growth culture medium after a time sufficient to produce the sQDs having an optical property.   
     
     
         28 . The method of  claim 27 , wherein the step of placing the selected bacterial strain in an aerobic fluid culture and inducing production of controlled size sQDs comprises the step of controlling at least one of growth rate or time to thereby control the size of the sQDs. 
     
     
         29 . The method of  claim 28 , wherein the bacterial strain is of the Family Xanthomonadaceae; and a member of a Genus selected from  Frateuria, Luteimonas, Lysobacter, Nevskia, Pseudoxanthomonas, Rhodanobacter, Stenotrophomonas, Xanthomonas , and  Xylella.    
     
     
         30 . The method of  claim 29 , wherein the bacterial strain is a member of the Genus  Stenotrophomonas.    
     
     
         31 . The method of  claim 30 , wherein the bacterial strain is selected from  S. acidaminiphila, S. dokdonensis, S. koreensis, S. maltophilia, S. nitritireducens , and  S. rhizophila.    
     
     
         32 . (canceled) 
     
     
         33 . The method of  claim 27 , wherein the growth culture medium further comprises at least one of sulfur and selenium. 
     
     
         34 . The method of  claim 27 , wherein the sQDs are soluble in water upon harvesting. 
     
     
         35 . The method of  claim 34 , wherein the sQDs have an average particle size of between about 1 to about 4 nm.