Journal of Biomaterials and Nanobiotechnology, 2012, 3, 362-370 http://dx.doi.org/10.4236/jbnb.2012.33034 Published Online July 2012 (http://www.SciRP.org/journal/jbnb) Biomineralization of Zinc-Phosphate-Based Nano Needles by Living Microalgae Giulia Santomauro 1* , Vesna Srot 2 , Birgit Bussmann 2 , Peter A. van Aken 2 , Franz Brümmer 3 , Horst Strunk 1 , Joachim Bill 1 1 Institute for Materials Science, University of Stuttgart, Stuttgart, Germany; 2 Stuttgart Center for Electron Microscopy—StEM, Max Planck Institute for Intelligent Systems, Stuttgart, Germany; 3 Department of Zoology, Institute for Biology, University of Stuttgart, Stuttgart, Germany. Email: * giulia.santomauro@imw.uni-stuttgart.de Received April 24 th , 2012; revised May 25 th , 2012; accepted June 9 th , 2012 ABSTRACT Up to now, chemical synthesis routes only provide restricted opportunities for the formation of structured nano particles. In contrast, living microorganisms generate nano materials of well defined shapes by the precise control of biomine- ralization. Here we reveal new principles for the generation of functional nano materials through the process of biomi- neralization. We used the detoxification mechanism of the unicellular alga Scenedesmus obliquus to generate a techno- logically interesting zinc-phosphate-based nano material. The algae were incubated in media with a sublethal zinc con- centration (6.53 mg Zn dm –3 ) for 4 weeks. Using BF- and ADF-STEM imaging combined with analytical XEDS we could show that nano needles containing phosphorus and zinc were formed inside the living cells. Furthermore, the cells incubated with zinc show a strong fluorescence. Our findings indicate that the algae used polyphosphate bodies for de- toxification of the zinc ions, leading to the generation of intracellular zinc-phosphate-based nano needles. Beside the technological application of this material, the fluorescent cells can be used for labeling of e.g. biological probes. This new experimental protocol for the production of an inorganic functional material can be applied also for other sub- stances. Keywords: Nano Needles; Biomineralization; Zinc Phosphate; Microalgae; Fluorescence 1. Introduction Due to their broad potential, nano materials are of grow- ing interest for technological applications. Zinc phos- phate nano particles can be used as corrosion inhibitors or as dental cement and hydrogelated zinc ultraphosphate glass powders serve for proton-conducting materials [1]. Zn 3 (PO 4 ) 2 serves as a host-lattice for fluorescent mate- rials like Zn 3 (PO 4 ) 2 :Eu [2]. Through chemical synthesis, nano materials are produced with high efforts in terms of high temperature or process engineering, e.g. spherical Zn 3 (PO 4 ) 2 nano particles can be synthesized via a polyol- mediated method at temperatures of 230˚C or an ultra- sonic-microwave route [3,4]. Preparation of Zn 3 (PO 4 ) 2 at room temperature resulted in highly aggregated spherical or sheet-like particles [5,6]. When yeast cells are used as catalytic templates, butterfly-like particles or agglome- rates of Zn 3 (PO 4 ) 2 are chemically precipitated on the ne- gatively charged surface of the yeast [7,8]. According to that, chemical synthesis routes only provide restricted opportunities for the generation of such inorganic solids with defined shape. In contrast to chemical synthesis, living organisms are capable of producing highly struc- tured nano particles by the precise control of the biomi- neralization processes [9]. e.g. sponge primmorphs are capable of the incorporation of titania into their nanospi- cules when incubated in an appropriate medium [10]. Due to the genetic control of the biomineralization, they react to a certain environment in always the same way, resulting in the reproducible synthesis of nano particles of a certain size and morphology. Since these processes proceed at ambient conditions, nano materials produced by microorganisms are very cost-effective and eco- friendly. When confronted to toxic elements in their en- vironment, microorganisms like algae can sequester them inside their cells in order to detoxify their surrounding. The intracellular sequestration of the toxic metal ions occurs via chelate formation with molecules like phyto- chelatins or phosphates of different chain length, result- ing in metal/phytochelatin or metal/(poly) phosphate complexes which are no more harmful to the organisms [11,12]. It is known, that the metal ions first bind on the cell wall of the algae to specific transport ligands as well * Corresponding author. Copyright © 2012 SciRes. JBNB