Binbin Hu

Biomimetic syntheses of pure or doped metal hydroxide nitrate thin films by a dual-template approach

Compact large area Zn5(OH)8(NO3)2·2H2O, Co5(OH)8(NO3)2·2H2O and Co-doped Zn5(OH)8(NO3)2·2H2O thin films with uniform surface morphology and good orientation were synthesized by an unusual dual-template biomimetic approach. In such a biomimetic system, a bovine serum albumin Langmuir monolayer was used as one organic matrix template, whereas the vapor–liquid interface generated by the vapor diffusion of catalyst (ammonia) served as the other nucleation template providing kinetic control. The crystallinity, morphology and overall chemical composition of thin films were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The formation process of the Zn5(OH)8(NO3)2·2H2O films was discussed in detail. Compared with the method with only organic template, the synergetic effect of the dual template plays an important role in the formation of thin films. The method developed here provides a novel route for growing large area and well-oriented thin films at room temperature.

The Biomimetic Mineralization Closer to a Real Biomineralization

In view of the huge timeframe Nature has to optimize and perfect functional materials to survive during the evolution and natural selection, as a result, biominerals, the organicinorganic hybrid materials are formed through biomineralzation, one of the most important processes for the organisms to produce for a variety of purposes, including mechanical support, navigation, protection, and defense (Lowenstam & Weiner, 1989; Stupp, et al., 1993; Weiner & Addadi, 2003). These biomaterials are generally molded into specifically designed devices with fascinating properties of superior materials properties and environmentally friendly synthesis and biocompatibility (Xu, et al., 2007) , in which the structure, size, shape, orientation, texture, and assembly of the constituents are precisely controlled over several hierarchy levels. Therefore, the understanding and ultimately mimicking of the processes involved in biomineralization may provide new approaches to the fabrication of specialized organic-inorganic hybrid materials, in other words, nature provides a perfect model for people to design and fabricate novel materials with special structures and functions through the biomimetic mineralization method (Mann, 2000). Based on these ideas a rapidly developing research field has evolved, which can be summarized as bioinspired or biomimetic materials chemistry (Mann, 1995; Colfen & Yu, 2005), is meanwhile already an important branch in the broad area of biomimetics (Mann, et al., 1993; Davis, et al., 2001; Colfen, 2003; Meldrum, 2003; Yu & Colfen, 2004). As the research is continuously developed, the main aim to mimic the syntheses of these biominerals, is not only to emulate a particular biological architecture or system, but also to abstract the guiding principles and ideas and use such knowledge for the preparation of new synthetic materials and devices (Dujardin & Mann, 2002). During the past decades, exploration as well as application of these bio-inspired synthesis strategies has resulted in the generation of complex materials with specific size, shape, orientation, composition, and hierarchical organization (Archibald & Mann, 1993; Antonietti & Goltner, 1997; Yang, et al., 1997; Li, et al., 1999; Estroff & Hamilton, 2001; Jones & Rao, 2002; Colfen & Mann, 2003; Dabbs & Aksay, 2003; Aizenberg, 2004). The human efforts in the fields of chemistry and materials science have led to the development of a complementary set of inorganic and hybrid materials with special characteristics. However, by mimicking the design and synthesis of, e.g., biomaterials, to date no synthetic materials have evolved that show properties which are superior to those found in their natural counterparts (Sommerdijk & With, 2008). It is