Recombinant peptide fusion proteins enable palladium nanoparticle growth

•Fusion protein consisting of multimeric metal binding peptide and green fluorescent.•Protein was constructed to direct nanoparticle synthesis.•The protein was contained in bacterial lysates of Escherichia coli and used in its crude (unpurified) form.•Palladium nanoparticles were spherical with no agglomeration observed.•Use of unpurified protein cost effective alternative to chemically synthesized peptides.