Biomimetic Preparation and Morphology Control of Mesoporous Silica - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 297

nanoparticles, mesoporous vesicles, molecular recognition, morphology control,
nanomachines, nanovalves, gatekeeper, stimuli-responsive release

13.1 Introduction

Hybrid material and self-assembly are two important characters in the study
of biominerals. The functionality of macroscopic materials is rarely expressed
and is embodied simply by pure chemical composition. Many natural bio-
materials, such as bone, cartilage, shell and diatom are composites composed
of various nanostructured blocks that are made of inorganic crystalline or
amorphous materials and organic molecular assemblies [3]. Many past stud-
ies have indicated that the organic molecules might control the nanostruc-
ture formation of the inorganic materials through molecular recognition.
Besides calcium minerals (e.g., calcium phosphate, calcium carbonate),
silica is one of the most important biominerals in nature and earliest forms
of biominerals on earth. Silica can be found everywhere, in the biominerals
of single-celled algae, bacteria, sponges, protozoa and higher plants in vivo
[3]. Its ultra-stable amorphous forms provide adjustable mesostructure.
Mesoporous silica as well as nano-silica widely exists in plants, sponges
and diatoms in the world. Because of its excellent biocompatibity, nontox-
icity and non-physiological activity, mesoporous silica is one of the most
promising carrier candidates for advanced drug delivery. The biomimetic
synthesis of porous silica is usually inspired by biomineralization of sponge
or diatom. During the formation process of diatom, a silaffi n protein ends
with polyamine fragments, works as a functional reaction site, and may
affect the pH of the local environment resulting in molecular recognition
by weak interaction and enrichment, or even condensation of particular
ions of silica precursor [4]. The formation of mesoporous silica adopted a
bionic processing self-assembly technique, which originates from the basic
principles of biomineralization. In the early stage of the study of mesopo-
rous silica, Stucky [6-8] and Mann [9-10] stated that the synthesis of the
mesoporous silica was a typical biomimetic biomineralization, which is in
light of the characteristic mesostructure of the biominerals.

13.2 Biomineralization and Biomimic Synthesis

13.2.1 Biomineralization and Morphogenesis

Evolution is a constantly optimized process. After billions of years of bio-
logical evolution, both the microstructure and behavior of biological sys-
tems of the entire biosphere are gradually self-adaptively optimized, and
this optimization is more prominent for biomaterials. It has been proved
that biomanufactured materials are superior. Teeth can be biologically
manufactured at 37°C, and their strength is even higher than by ceramic