Amelogenin and enamel biomimetics Ruan, Qichao; Moradian-Oldak, Janet
Journal of materials chemistry. B, Materials for biology and medicine,
01/2015, Volume:
3, Issue:
16
Journal Article
Peer reviewed
Open access
Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the ...importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization
in vitro
, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel.
Mature tooth enamel is acellular and does not regenerate itself.
•The adiabatic shear failure process of solids was investigated for the first time by dynamic tests synchronically combined with high-speed photography and infrared temperature measurement.•The key ...characteristics of ASB, such as temperature, critical strain, propagation speed and cooling rate were systematically studied.•The experimental results shows that the apparent temperature rise might have occurred after ASB initiation, indicating it might not be the causation but the consequences of ASB.•The discovery might help to clarify the causality of ASB and serve as the starting point for further physical, mechanistic and mathematic studies of ASB.
One of the most important issues related to dynamic shear localization is the correlation among the stress collapse, temperature elevation and adiabatic shear band (ASB) formation. In this work, the adiabatic shear failure process of pure titanium was investigated by dynamic shear-compression tests synchronically combined with high-speed photography and infrared temperature measurement. The time sequence of important events such as stress collapse, ASB initiation, temperature rise and crack formation was recorded. The key characteristics of ASB, such as width, critical strain, temperature, propagation speed and cooling rate were systematically studied. The maximum propagation velocity of ASB is found in this work to be about 1900 m/s, about 0.6Cs (Cs is the shear wave speed). The maximum temperature within ASB is in the range of 350–650 °C, while the material close to ASB is also heated. The cooling rate of ASB is on the order of 106 °C/s, indicating that it needs a few hundreds of microseconds for the ASB to cool down to the ambient temperature. One important observation is that the apparent temperature rise occurs after ASB initiation, which indicates that it might not be the causation but the consequences of ASB. Further efforts are called for confirmation of this notion because of its significance.
The gradual discovery of functional domains in native enamel matrix proteins has enabled the design of smart bioinspired peptides for tooth enamel mimetics and repair. In this study, we expanded upon ...the concept of biomineralization to design smaller amelogenin-inspired peptides with conserved functional domains for clinical translation. The synthetic peptides displayed a characteristic nanostructured scaffold reminiscent of ‘nanospheres’ seen in the enamel matrix and effectively controlled apatite nucleation in vitro resulting in the formation of smaller crystallites. Following application of the peptides to sectioned human molar teeth, a robust, oriented, synthetic aprismatic enamel was observed after 7 days of incubation in situ. There was a two-fold increase in the hardness and modulus of the regrown enamel-like apatite layers and an increase in the attachment of the tooth-regrown layer interface compared to control samples. Repeated peptide applications generated multiple enamel-like hydroxyapatite (HAP) layers of limited thickness produced by epitaxial growth in which c-axis oriented nanorods evolved on the surface of native enamel. We conclude that peptide analogues with active domains can effectively regulate the orientation of regenerated HAP layers to influence functional response. Moreover, this enamel biofabrication approach demonstrates the peptide-mediated growth of multiple microscale HAP arrays of organized microarchitecture with potential for enamel repair.
Carbonated hydroxyapatite is a main inorganic component of hard tissues in vertebrates, which usually appears as orderly arranged superstructures in tissues and exhibits excellent biological and ...mechanical properties. Recently, mimicking the structure and composition of organisms in the field of biomaterials and tissue engineering has caused much attention. Herein, a family of orderly arranged textures composed of two-dimensional carbonated hydroxyapatite in nanoscale was prepared in the complex matrix of succinylated gelatin and cetyltrimethyl ammonium bromide, which is an analogue of bone in calcified turkey tendon. The building blocks of carbonated hydroxyapatite nanosheets elongate along the c-axis direction and self-organize into well-aligned bundles. This study may offer an example to design and synthesize laminated materials and may provide new evidence in support of the hypothesis that hierarchical structures in nature result from cooperative interactions between biological membrane and crystal growth.
The film resistance
(
R
f
)
and the charge-transfer resistance
(
R
ct
)
increase in diverse ways at different growing stages, revealing the buildup mechanism of layer-by-layer assembled films.
The ...layer-by-layer (LbL) assembly as a simple and effective method has been extensively used to prepare polyelectrolyte films but the buildup mechanism is expected to be further clarified. In this work, the structure and formation mechanism of LbL-assembled heparin/chitosan multilayer composite films were characterized by electrochemical system, scanning electron microscope and atom force microscope. The results revealed that the film grew linearly in the first 10 bilayers based on measured linear increase of film resistance with number of layers, while the film grew exponentially in the later 10 bilayers based on measured nonlinear increase of film resistance. The charge-transfer resistance increased in an oscillatory way or a linear way at different growing stages, which was discussed with their formation mechanism and the interfacial structure on electrode. A buildup mode of the LbL film was suggested based on the structural and electrochemical characters.
The WC–Co coating obtained by atmospheric plasma spraying (APS) was modified by Cu electrochemical impregnation. The copper has infiltrated into and filled up the pores in WC–Co coating. The ...tribological properties of the coating against the stainless steel ball as sliding pairs were investigated with a ball-on-disc (BOD) configuration in air at room temperature. The as-prepared samples were characterized by means of optical microscope, scanning electron microscope and X-ray diffraction. It was found that the frictional behavior of the WC–Co coating followed by Cu electrochemical impregnation was superior to that of WC–Co coating. The wear mechanism of the WC–Co coating followed by Cu electrochemical impregnation was microcutting, whilst that of a WC–Co coating was the fatigue wear. The improvement in tribological properties of the WC–Co coating followed by Cu electrochemical impregnation was attributed to the formation of self-lubricating Cu film on the wear surface which induces the transformation of wear mechanism.
It is an interesting phenomenon for natural organisms to have control over the shapes and sizes of inorganic nanocrystals and arrange them into ordered superstructures. This phenomenon attracts many ...attempts to mimic the biomineralization process to synthesize novel materials. In the present work, a new superstructure of hexagonal vaterite mesocrystals consisting of nanocrystals has been synthesized via a mesoscale transformation process by controlled release of carbon dioxide through slow decomposition of dimethyl carbonate in the presence of cetyltrimethyl ammonium bromide at room temperature. The superstructures are composed of hundreds of well-stacked vaterite flakes, which build spheres with an axis and two poles. We can find that mesocrystal plates at the poles are arranged with their surfaces parallel to the axis, whereas the plates at the equator of the spheres are arranged with their surface vertical to their axes. The flakes present the unstable (001) planes and show hexagonal shapes with a thick core and thin edges. The subunits of vaterite flakes consist of oriented aggregation of nanocrystals which are transformed from the amorphous phase. New evidence of the mesoscale transformation process has been observed in detail by measuring the structures of the products at different reaction stages, revealing that the product evolves from amorphous oblate particles to doughnutlike particles, which crystallize and delaminate into superstructures. The mineralization process is discussed with the cooperative reorganization of coupled inorganic and organic components relevant for models of matrix-mediated nucleation in biomineralization. This contribution will be helpful in understanding the aggregation-driven formation of complex and higher-order structured materials as well as the biomineralization mechanisms.
One of the most important issues related to adiabatic shear failure is the correlation among temperature elevation, adiabatic shear band (ASB) formation and the loss of load capacity of the material. ...Our experimental results show direct evidence that ASB forms several microseconds after stress collapse and temperature rise reaches its maximum about 30 μs after ASB formation. This observation indicates that temperature rise cannot be the cause of ASB. Rather, it might be the result of adiabatic shear localization. As such, the traditional well-accepted thermal-softening mechanism of ASB needs to be reconsidered.
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Mimicking the dynamics of mineral loss and gain involved in dental caries formation can help us evaluate and compare the mineralization efficacy of different treatment agents used in enamel ...remineralization. Here, we offer an abridged study design outlining the preparation of tooth samples, creation of artificial dental lesions, application of a peptide, and characterization of the regrown enamel-like mineral layer.
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