According to the degree of biological mineral control, biomineralization could be divided into two categories: biological induction and biological control. Bio-induced biomineralization is a process caused by physiological activities of organisms, such as metabolism, inhalation of oxygen, exhalation of carbon dioxide by respiration, as well as establishment of cell walls, which change the physical and chemical conditions of the surrounding environments. This mineralization is not guided by specific cell tissues or biological macromolecules, resulting in arbitrary orientation of crystals and lack of unique morphology. Negatively charged cell walls (containing carboxyl and phosphatidyl groups) combine Fe³⁺ ions by electrostatic interaction, and Fe³⁺ ions react with silicic acid to form iron silicate. This process is seldom controlled by cells, and its crystalline form is similar to that of iron silicate that is produced in inorganic solutions. Biologically controlled mineralization is a process that is caused by biological physiological activities and controlled by biology in three aspects: space, structure, and chemistry. It occurs in delineated confined spaces. Biomineral organic matter is formed with high content, unique crystallization habit, uniform size, uniform shape, and regular arrangement.

There are two forms of mineralization: one is normal mineralization, such as skeleton, teeth and shellfish, formation of shells, and so on. Another is abnormal mineralization, such as stones, dental stones and caries teeth, and so on. There are two theories to explain this biomineralization. Solution crystallization theory and polymer-induced liquid phase precursor mineralization theory. For solution crystallization theory, Type I collagen molecules self-assemble into a native “hole”, the “hole” contain negatively charged amino acids, the –COO– could bind to Ca²⁺, which lead to the deposition of Ca²⁺ in the “hole”[15]. After deposition, the calcium phosphate (Ca-Pi) is electrostatically formed through binding. The Ca–Pi nucleus is the basic building blocks of bone structure [16]. In addition, the “hole” is the nucleation site of hydroxyapatite crystals, which is another important component of bones [17]. For polymer-induced liquid phase precursor mineralization theory, highly hydrated amorphous calcium phosphate phase nanometer droplets penetrate into the pores and voids of collagen fibers the hydrates lose water and crystallize in the pores and voids of collagen fibers [18]. The calcification of atherosclerosis (AS) plaque is a typical sample of abnormal mineralization.

Mineralization in organisms can be divided into four stages. (1) Organic macromolecules are pre-assembled into ordered structures. Insoluble organic matter in organisms constructs an organized micro-reaction environment before mineral deposition, which determines the location of inorganic nucleation and the function of mineral formation. This stage is the precondition of biomineralization. (2) Molecular recognition of organic-inorganic interfaces controlling crystal nucleation and growth. (3) Growth regulation enabling the initial assembly of crystals to form subunits. (4) Cell prepressing, forming biominerals with multilevel structure by assembling subunit minerals. It is believed that biomineralization is controlled by varying factors. The formation of biominerals is often the result of the synergistic action of various factors, including pH, temperature, and matrix.

The mineralization process in organisms is very complex. Recognizing the formation mechanism of biominerals and matrix, cell and other symbiosis regulation of minerals and substances will be very helpful. Most of the research simply established simulation system and coordinated the regulation of biological macromolecules outside of the organism. There are very few studies on the control effect. Accordingly, we need to be closer to organisms. Further study on the specific regulation of biological macromolecules under environmental conditions function and synergistic regulation to further study organisms in matrix mineralization processes, cell-mineral interactions, to elucidate biominerals.

A deep molecular-level mechanistic understanding of how proteins participate in the nucleation and growth of inorganic crystals (both in vitro and in vivo) can be achieved by computational methods at the atomic scale, as shown in Figure 3(A) [42].

Michael S. Pacella et, al. compared the results of the Rosetta-Surface algorithm to an experimental benchmark of kinetic and thermodynamic measurements on peptide−biomineral interactions taken from atomic force microscopy, and successfully identified which mineral face and step edges will bind peptides the strongest [42]. The interaction effect between proteins and crystal can be illustrated using examples from biomineralization, as well as by the immune responses from pathological crystallizations to crystalline antigens, as shown in Figure 3(B). A.J., et al. [44] have employed self-assembled monolayers (SAMs) on Au or Ag, with disordered head groups, to induce the formation of an amorphous CaCO₃ film. The mechanism of the molecular interactions occurred at the interface between the inorganic mineral and the macromolecules [45]. A form of additive manufacturing, selective laser sintering (SLS) uses a roller feed system, a heated chamber, and a laser to fuse plastic, ceramic powder layers or metal, together form a wide variety of solid objects [46]. As opposed to other printing methods that restrict model geometry or require removable, unfused powder provides support for parts. Together with the biocompatibility of the material feedstocks, this process also gives printed objects a rough surface of partially fused powder and provides a viable avenue for fabricating a wide variety of effective high-surface area substrates for tissue engineering and biomedical implants. Furthermore, the model of three-dimensional printed frameworks has tremendous potential for synthesis of biomaterials. It is especially effective when combined with post-synthesis chemical treatment, and this will be discussed in the later section.

Traditional biomineralization studies emphasize the bionic design and preparation of materials by imitating nature, highlighting the regulation of inorganic crystallization by organic systems, thus improving the properties of materials. The new trend of biomineralization research is to use natural strategies for realizing the regulation of biological organisms through inorganic materials, highlighting the use of material systems to achieve bio-functional transformation.

In 2008, Tang Ruikang’s team successfully realized the mineralization transformation of yeast cells [47], and proposed that using the biomineralization strategy for more biological species could be endowed with new functions through material shells. For example, the preservation of vaccines is highly dependent on the cold chain. Through biomimetic mineralization, the team constructed a new vaccine-calcium phosphate complex, which greatly enhanced the thermal stability of vaccines on the basis of maintaining the original efficacy, and initially realized the construction of heat-stable vaccines independent of refrigerators. Biomimetic mineralization can not only enhance the structural stability of organisms through materials, but also change the original functions of organisms. By inducing the spontaneous accumulation of green algae through biomimetic mineralization of green algae, the group can activate hydrogenase while also ensuring the activity of photosynthetic system II, thus changing the photosynthetic pathway of green algae, and directly decompose water to produce hydrogen under natural conditions. Its hydrogen production efficiency is equal to the normal photosynthetic efficiencies.

When compared with natural or synthetic minerals, biominerals often exhibit excellent mechanical and other properties. The reason is that biominerals have multilevel ordered micro- and nano-structures with specific morphologies, which are also consistent with the macro-scale structure. The acquisition of multilevel ordered mineral structure depends on the synergistic effect of various biomass macromolecules in the process of biomineralization. Clearly, understanding this synergistic effect can better guide material chemists to make controllable composites to obtain excellent mechanical and other properties. However, it is difficult to observe the biomineralization process in situ, and the information that is provided by static biomineral microstructural analysis is relatively limited. Therefore, controllable biomimetic mineralization is still a major problem in the field of material synthesis. Up to now, biomimetic mineralization research is mostly based on empirical knowledge, and biomimetic mineralization research based on controllable route design is few and far between. Calcium carbonate films with shellfish-like prism structure were synthesized by the total synthesis method for the first time, as shown in Figure 4(A), and precise control of the micro-structure of bionic films was achieved, resulting in excellent mechanical properties [48].

Calcium oxalate needle crystals are formed plants using protein nanowires (14 kDa) embedded in needle crystals as templates in banana. Calcium oxalate nanospheres are induced to deposit orderly along the template and they eventually form hexagonal pyramidal mesoscopic structures driven by organic-inorganic self-assembly [49]. This study effectively reveals the structure-functional relationship between the chemical evolution of plant crystal morphology and the environment during the long evolutionary process, as shown in Figure 4(B). That is, in the physiological micro-environment of excessive calcium or oxalic acid metabolism (C4 plants), plants can maximize the capture of calcium and oxalic acid in the limited all oocyte, thus maintaining the metabolism of inorganic calcium and organic acid in plants. It is also of great significance to the development of bionic materials and the study of human pathological mineralization, such as kidney stones (calcium oxalate is also the main component).

Biomineralization, as a functional strategy in the process of biological evolution, can make organisms more adaptable to the environment and they produce evolutionary chains that are more conducive to their own development. It also provides a reference direction for human beings to realize the regulation of biological organisms through materials. By learning from nature, the study of biomineralization has realized the transformation from the regulation of material crystallization by biological system to the improvement of organisms by using materials, which provides a new direction for the sustainable development of human beings.

A rapid synthesis method of multifunctional macro-graphene composites was developed. Graphene oxide was added into biomimetic mineralized gel system to form graphene oxide, amorphous calcium carbonate nanoparticles, and polyacrylic acid cross-linked network structure. The soft and hard state of the graphene composite can be controlled by moisture content. It is also found that the material has excellent plasticity and self-healing ability, and it is expected to be used in multi-scale rapid processing and forming of graphene materials [50].