Abstract
Biomineralization, the precipitation of various inorganic compounds in biological systems, can be regulated in terms of the size, morphology, and crystal structure of these compounds by biomolecules such as proteins and peptides. However, it is difficult to construct complex inorganic nanostructures because they precipitate randomly in solution. Here, we report that the elemental composition of inorganic nanocomposites can be controlled by site-specific mineralization by changing the number of two inorganic-precipitating peptides bound to DNA. With a focus on gold and titania, we constructed a gold-titania photocatalyst that responds to visible light excitation. Both microscale and macroscale observations revealed that the elemental composition of this gold-titania nanocomposite can be controlled in several ten nm by changing the DNA length and the number of peptide binding sites on the DNA. Furthermore, photocatalytic activity and cell death induction effect under visible light (>450 nm) irradiation of the manufactured gold-titania nanocomposite was higher than that of commercial gold-titania and titania. Thus, we have succeeded in forming titania precipitates on a DNA terminus and gold precipitates site-specifically on double-stranded DNA as intended. Such nanometer-scale control of biomineralization represent a powerful and efficient tool for use in nanotechnology, electronics, ecology, medical science, and biotechnology.
Highlights
Biomineralization, the precipitation of various inorganic compounds in biological systems, can be regulated in terms of the size, morphology, and crystal structure of these compounds by biomolecules such as proteins and peptides
Conventional production methods such as hydrothermal synthesis and chemical reduction have some problems, as follows: 1) these conventional methods do not offer controlled size and structure; 2) it is difficult for these methods precisely control the elemental composition of inorganic nanocomposites; 3) these methods generally consume a considerable amount of energy; and 4) environmentally hazardous substances such as reducing agents, strong acids, and strong bases are often used
(2) Peptides can be conjugated with functional groups and molecules other than amino acids[20,21,22,23,24], and such functionalized peptides can be distributed on wellshaped organic nanostructures that serve as templates for mineralization, such as DNA, which is used as DNA origami
Summary
Biomineralization, the precipitation of various inorganic compounds in biological systems, can be regulated in terms of the size, morphology, and crystal structure of these compounds by biomolecules such as proteins and peptides. In conventional mineralization solves problems 3) and 4) mentioned above 1) and 2) remain (i.e., because inorganic compounds precipitate randomly in solution, conventional mineralization cannot offer precise control of the structure, distribution, and elemental composition of inorganic nanocomposites). Mineralization using these molecules is expected to produce inorganic nanocomposites with various elemental compositions With these aims in mind, we applied to nanometer-scale site-specific mineralization to attempt to solve problems 1) and 2) using peptides as inorganic-precipitating molecules and DNA as wellshaped template molecules. The elemental composition of the inorganic nanocomposites is expected to be controlled at the nanometer level by changing the number of peptides bound to the template DNA using our nanometer-scale site-specific mineralization method
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