Manufacturing and characterization of Pd-nanoparticles formed on immobilized bacterial cells

Biological ceramic composites (biocers) were used as a template to produce Pd(0)-nanoparticles. The metal binding cells of the uranium mining waste pile isolate Bacillus sphaericus JG-A12 were used as biological component of the biocers and immobilized by using sol-gel technology. Vegetative cells and surface layer proteins of this strain are known to bind high amounts of Pd(II) that can be reduced to Pd(0) particles by the addition of a reducing agent. After embedding into sol-gel ceramics, the cells retained their Pd(II)-binding capability. Pd(0)-nanoclusters were produced by the addition of hydrogen as reducing agent after the sorption of Pd(II). The formed Pd(0) nanoparticles were investigated by EXAFS-spectroscopy. The particles had a size of 0.6-0.8 nm. The thus immobilized Pd nanoparticles possess very interesting physical and chemical properties and are of interest for technical applications.