Morphology of gold nanoparticles synthesized by filamentous cyanobacteria from gold(I)-thiosulfate and gold(III)--chloride complexes.

Plectonema boryanum UTEX 485, a filamentous cyanobacterium, has been reacted with aqueous Au(S(2)O(3))(2)(3)(-) and AuCl(4)(-) solutions ( approximately 400-550 mg/L Au) at 25-100 degrees C for up to 1 month and at 200 degrees C for 1 day. The interaction of cyanobacteria with aqueous Au(S(2)O(3))(2)(3)(-) promoted the precipitation of cubic (100) gold nanoparticles (<10-25 nm) at membrane vesicles and admixed with gold sulfide within cells and encrusted on the cyanobacteria, whereas reaction with AuCl(4)(-) resulted in the precipitation of octahedral (111) gold platelets ( approximately 1-10 microm) in solutions and nanoparticles of gold (<10 nm) within bacterial cells. Functional groups imaged by negative ion TOF-SIMS on (111) faces of the octahedral platelets were predominantly Cl and CN, with smaller amounts of C(2)H and CNO.