TITOLO
Biosilica electrically-insulating layers by soft lithography-assisted biomineralisation with recombinant
silicatein
Dario Pisignano (dario.pisignano@unisalento.it)
Collaborators
Alessandro Polini, Stefano Pagliara, Andrea Camposeo and Adriana Biasco
at National Nanotechnology Laboratory of Consiglio Nazionale delle Ricerche-Istituto Nanoscienze,
Università del Salento, via Arnesano, I-73100 Lecce (Italy).
Heinz C. Schröder and Werner E. G. Müller
at Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University,
Duesbergweg 6, D-55099 Mainz (Germany).
Abstract (max 1500 caratteri)
Silica represent a key material for realization of microelectronic and optical components. In this work we
showed silica microstructures and films obtained in a biomimetic way, using the micro-contact printing
technology and a recombinant protein derived from sponges, named silicatein α. Protein micropatterns
were successfully realized on silicon based substrates, and investigated by fluorescent microscopy after
fluorescein-based staining. By using environmentally benign conditions, tetraethylorthosilicate was used as
precursor of the biomineralisation process, which was monitored over time by several complementary
microscopy methods. The electrically-insulating properties of biosilica films were assayed for the first time,
demonstrating the potential production of next generation electronic components utilizing biologic
pathways and mild production conditions.
Testo (max 3300 caratteri)
Silica films are ubiquitously used in many fields, e. g. as coatings for biomedical surfaces and devices (for
tissue engineering, controlled drug delivery, surface modification, transplants, etc.), catalytic, diagnostic
and sensing surfaces, composites, smart surfaces, optics and optoelectronics (being optically transparent,
as dielectric layer for interferential elements, for light-emitting devices etc.), for microelectronics and
nanoelectronics (as gate dielectric layers for field-effect transistors and other electronic devices).
Unfortunately, the commonly used production processes of silica surfaces, at both laboratory and industrial
scales, are usually carried out by processing at high temperatures, extreme conditions of pressures, and
strongly acid and basic environments. The controlled realization of silica patterns and the production of
silica by low-cost, gentle biomineralization processes could be instead a powerful method for the
environmentally-friendly realization of coatings and devices, because many living organisms are able to
synthetize silica under mild, physiological conditions.
Silicateins [1, 2] are peculiar proteins from sponges, able to catalyze the reaction of silica polymerization to
give ordered structures. In the framework of the European Project “Biomineralization for lithography
and microelectronics” (BIO-LITHO), we used for the first time recombinant silicateins to produce
micropatterns and films on silicon, and to assess the electrically-insulating properties of the obtained
biosilica.
The here proposed method extends biosilicification to the controlled fabrication of miniaturized silica
elements by physiological processing conditions, which cannot be addressed by conventional technologies
[3]. Patterning silicatein and realizing different silica geometries can be particularly useful as electrical
insulating micro-building blocks in complex circuits. We showed how to microfabricate biosilica stripes and
films just by tuning the incubation time in silica precursor solution. Moreover, the recent works on
biomedical applications of biosilica clear the way for its use as a new bioactive material.
The Suberites domuncula demosponge, and schematic illustrations of the steps for realizing biosilica
structures [3].
References
[1] J. N. Cha, K. Shimizu, Y. Zhou, S. C. Christiansen, B. F. Chmelka, G. D. Stucky, D. E. Morse, Proc. Natl.
Acad. Sci. USA 1999, 96,361.
[2] H. C. Schröder, X. Wang, W. Tremel, H. Ushijima, W. E. G. Müller, Nat. Prod. Rep. 2008, 25, 455.
[3] A. Polini, S. Pagliara, A. Camposeo, A. Biasco, H. C. Schröder, W. E. G. Müller, D. Pisignano, Adv. Mater.
2011, 23,.