Please cite this article in press as: Gaidhani SV, et al. Bio-reduction of hexachloroplatinic acid to platinum nanoparticles employing Acinetobacter calcoaceticus. Process Biochem (2014), http://dx.doi.org/10.1016/j.procbio.2014.10.002 ARTICLE IN PRESS G Model PRBI-10252; No. of Pages 7 Process Biochemistry xxx (2014) xxx–xxx Contents lists available at ScienceDirect Process Biochemistry jo ur nal home p age: www.elsevier.com/locate/procbio Short communication Bio-reduction of hexachloroplatinic acid to platinum nanoparticles employing Acinetobacter calcoaceticus Sharvari V. Gaidhani a , Richa K. Yeshvekar a , Utkarsha U. Shedbalkar b , Jayesh H. Bellare c , Balu A. Chopade a,b,∗ a Institute of Bioinformatics and Biotechnology, University of Pune, Pune 411007, Maharashtra, India b Department of Microbiology, University of Pune, Pune 411007, Maharashtra, India c Department of Chemical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400076, India a r t i c l e i n f o Article history: Received 27 May 2014 Received in revised form 13 September 2014 Accepted 3 October 2014 Available online xxx Keywords: Acinetobacter calcoaceticus Monodispersed PtNP HR-TEM EDAX AFM Protein profile a b s t r a c t Acinetobacter calcoaceticus PUCM 1011 efficiently synthesized platinum nanoparticles (PtNP) of size 2–3 nm intracellularly when challenged with hexachloroplatinic acid. Salt concentration (1 mM), tem- perature (30 ◦ C), pH (7) and incubation period (72 h) influenced the efficiency of monodisperse cuboidal PtNP synthesis. Resolution of ordered lattice fringes with “d” value of 0.23 nm corresponding to (1 1 1) plane and EDAX confirmed presence of metallic platinum. AFM, TEM and HR-TEM confirmed synthesis of PtNP and its effect on cell viability. Total cell protein profile for 120 h with an interval of 24 h after PtNP synthesis revealed prominent four protein bands (97, 66, 43 and 29 kDa) when compared to con- trol. Combinations of three proteins initiated PtNP synthesis within 4 h in range of 1–4 nm and few in picometers under HR-TEM. This is the first report of PtNP synthesis employing whole cell and total cell protein of A. calcoaceticus. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction In the last decade, nanotechnology has advanced remarkably due to its applications in various fields. Pertaining to various drawbacks of physical and chemical synthesis, biological meth- ods have gathered tremendous attention. The biological procedures are nontoxic, ecofriendly and less sludge producing, finding large applications in biomedicine [1,2]. Biological methods involve use of microorganisms, plant extracts, phages and various biomolecules like nucleic acids as templates for nanoparticle synthesis, pertain- ing to their ability of reducing metal salts at ambient temperature and pressure [1–5]. Biological synthesis of silver and gold nanopar- ticles has been extensively studied [1,5–7]. However, optimization of physicochemical parameters affecting nanoparticle synthesis is less studied. Platinum nanoparticles (PtNP) have found applications in medicine [8], catalysis [9], hydrogen storage materials [10] and fuel cells [11]. Cis-diaminedichloroplatinum (Cis-platin) and ∗ Corresponding author at: Department of Microbiology, University of Pune, Pune 411007, Maharashtra, India. Tel.: +91 20 25690462. E-mail address: bachopade@gmail.com (B.A. Chopade). platinum based complex [FePt@CoS2] have been used extensively as potential anticancer drugs [12]. Synthesis of PtNP by physical and chemical methods is studied well, but it involves use of toxic chemicals for synthesis and stabilization [9,13]. Biological synthe- sis of PtNP, employing Fusarium oxysporum [14,15], Plectonema boryanum [16] and metal ion reducing bacterium Shewanella algae [17] has been reported earlier. However, complete characteriza- tion has been performed for PtNP produced by F. oxysporum [14]. Involvement of cytoplasmic and periplasmic hydrogenase enzymes from F. oxysporum [14] and hydrogenases from sulphate reducing bacteria [18] in reduction of Pt(IV) to Pt(0) has also been reported. Moreover, the role of purified hydrogenase in two-step mecha- nism of PtNP synthesis has been demonstrated at two different conditions of pH and temperature [19]. Such differences in pH and temperature were not required for reduction of platinum salt in the present study. Acinetobacter spp. are commonly found in rhizosphere of impor- tant crop plants and exhibit potent plant growth promoting properties [20–22]. Its ability to solubilize phosphate and zinc pro- posed its use in synthesis of metal nanoparticles. There are reports on synthesis of silver nanoparticles by Acinetobacter calcoaceticus [6,7]. However, synthesis of PtNP employing A. calcoaceticus has not been reported yet. In present study we report A. calcoaceticus http://dx.doi.org/10.1016/j.procbio.2014.10.002 1359-5113/© 2014 Elsevier Ltd. All rights reserved.