Growth kinetics of hydroxyapatite crystals revealed by atomic force microscopy (2023)

Calcium phosphates (CaP) are an important class of biominerals present in living organisms. Given the high biocompatibility and adaptable reactivity/resorption of these compounds, strategies are being developed to prepare biomedicine-inspired synthetic ceramics for biomedical applications such as bone replacement and regeneration, but also in other emerging fields such as nanomedicine. Two main families of CaP are particularly studied: apatites (well-crystallized HA hydroxyapatites, but also nanocrystalline biomimetic apatites) and tricalcium phosphates (TCPs, especially high-temperature forms α and β or low-temperature forms, amorphous TCP and apathetic TCP). These compounds are by far the most commonly used PCa phases in bone substitute materials and offer a wide range of bioceramic based systems with different properties (mechanical, biological, chemical, thermodynamic…) to meet clinical needs. The main application domain is the production of resorbable or non-resorbable bone implants that can also bind drugs and other active substances. This article will review apatite and tricalcium CaP compounds in terms of structure, synthesis, processing routes, physicochemical characteristics and main biological properties. This also includes the effects of ionic substitutions and compounds with active substances. Biphasic systems such as HA/β-TCP, also known as Biphasic Calcium Phosphate Ceramic (BCP), will also be discussed. Finally, concluding remarks and points of view will be given.

Although the usefulness of calcium isotopes is wide, examples of applications are still relatively few. Part of this deficiency, as with many metal isotope systems, may be due to the perception that an analytical tool is hard to come by. Alternatively, potential users may be put off by the feeling that calcium isotopes are ambiguous, difficult to interpret and/or complicated by too many interrelated processes. Here, we provide an overview of available quantitative modeling approaches to facilitate the interpretation of calcium isotopes in terrestrial systems, in particular their ability to push interpretation beyond quality. While no method is perfect, the variety of approaches described here offers an accessible toolkit that is extremely valuable. We suggest that the calcium isotope community expand the use of such techniques, keeping in mind their limitations and striving to improve current methods over time.

The growth pathways of calcium phosphate (Ca) minerals are still being debated, but non-classical growth pathways involving any growth mode that involves the attachment of primary particles rather than monomeric ions are now believed to dominate the classical mechanisms over a wide range of conditions. growth conditions. The desolvation of cations during ion-by-ion growth is related to the preferential absorption of isotopically light Ca in Ca-containing phases, so the composition of Ca isotopes in Ca-containing minerals may help elucidate the growth mechanism. Here, we combine stable Ca isotope analysis with mineralogical characterization and imaging of nanoscale growth characteristics to determine for the first time rate-dependent Ca isotope fractionation during hydroxyapatite (HAP) seeded growth involving a Ca precursor. Octacalcium phosphate (OCP). Our data reveal that the growth rate is strongly attenuated by pH, and the Ca isotope fractionation between the solid solution and the growth solution is independent of the growth rate between 1.9 × 10⁻⁹y 2,8×10⁻⁸molCam⁻²S⁻¹. In addition, nanoscale surface topography images reveal direct deposition of primary particles on the surface of HAP seeds after long-term growth, providing visual evidence of a non-classical growth path. Together, these findings support the hypothesis that hydroxyapatite growth is predominantly non-classical. The process of cluster nucleation from the bulk solution and binding of these clusters to the seeded PAHs does not seem to imply a significant kinetic isotope effect, suggesting that the abiogenetically formed Ca phosphates probably retain the Ca isotope composition of the bulk solution. crystals formed. .

In-situ remediation of uranium (U) contamination of groundwater by precipitation of uranyl phosphate (UP) minerals is a promising passive approach to rehabilitate aquifers affected by mobile hexavalent U (U(VI)). We demonstrated the effectiveness of stabilizing U in a polluted aquifer using a metastable form of hydroxyapatite (mHAP) derived from fish bone. This material was reacted with groundwater contaminated with depleted uranium (DU) in both in situ ambient flow and ex situ pumped flow. Immobilized U under ambient and flow-accelerating conditions was strongly bound in the solid phases, with removal of over 99% of U from groundwater. Stable U absorption greater than 50 g U/kg solids was achieved by precipitation of the crystalline U-P melanvite mineral. Previous field trials immobilized U only by sorption [Fuller et al., 2003,send science technology.37, 4642.], possibly due to groundwater conditions with higher pH and alkalinity that increase the solubility of the U-P phases through aqueous complexation. Our study is the first to demonstrate the feasibility of immobilizing U by UP precipitation from natural groundwater. These findings suggest that in groundwater contaminated with U(VI) with approximately neutral pH and low carbonate alkalinity, fishbone hydroxyapatite is an effective in situ U(VI) remediation material that can be easily applied without the need for remediation.

We discuss an alternative soaking technique without hydrogel for micropatterning bioactive ceramics on substrates with room temperature wettability patterns. Substrates with wettability patterns were produced by partially removing the self-assembled monolayers on the slides using a UV-Ozone mask. Hydroxyapatite scaffolds or calcium carbonate films were selectively formed on the hydrophilic surface of the substrates with the wettability pattern by alternately soaking the substrates with the wettability pattern in two types of calcifying solutions. Substrates with wettability patterns formed from hydroxyapatite scaffolds were immersed in hydroxyapatite precursor to grow hydroxyapatite crystals. The c-plates of the hydroxyapatite crystals were very aligned parallel to the substrates at an early stage. This technique allows bioactive ceramics to be micromodelled at low cost, low energy and short time as the technique does not require bioactive glasses which require a calcination process to activate them, nor hydrogels which require a long diffusion time of the hydroxyapatite precursor contributing to stencil application . for cells from biological cultures and cell matrices for medical diagnostics with an environmentally friendly production process in the future.

Nanocrystalline calcium phosphate apatites are the main inorganic part of hard tissues, and more and more emphasis is being placed on obtaining synthetic analogues, the so-called From both the basic and application point of view, accurate characterization of nanocrystalline apatites, including their specific surface features, and in-depth knowledge of crystallization aspects are a prerequisite for trying to understand mineralization phenomena.is aliveas well as for the design of innovative bioactive materials, which can then be used in bone tissue engineering, as self-supporting scaffolds and fillers or in the form of coatings, but also in other fields such as drug delivery or medical imaging. In addition, interfacial phenomena are of great importance for better understanding biomineralization and tracking the behavior of biomaterials at or near end-of-use conditions. From this point of view, both adsorption and ion exchange represent fundamental processes involving the surface of apatite nanocrystals, possibly doped with foreign elements or functionalized with organic molecules of interest. In this review article, we will discuss these various issues in detail based on an extensive review of the literature. We will also pay attention to the fundamental physicochemical and behavioral differences between nanocrystalline apatites (whether of biological origin or their synthetic biomimetic analogues) and stoichiometric hydroxyapatites.

Materials Letters, vol. 199, 2017, pages. 32-36

In orthopedics and dentistry, new approaches to fabricating mechanically strong and biomimetic bioactive coatings are highly desirable to truly improve the clinical performance of coated implants compared to uncoated implants. In this article, a biological apatite coating is deposited for the first time by plasma-assisted deposition of a natural source of apatite. Specifically, we deposited bone apatite-like (BAL) thin films from target bone apatites by pulsed electron deposition (PED). The morphology, composition, structure and mechanical properties of deposited and annealed LAB and stoichiometric hydroxyapatite (HA) layers were investigated. While the deposited LAB and HA layers were poorly crystalline at room temperature, they crystallized to a degree very close to natural apatite after annealing at 400°C. In addition, FTIR analysis showed that the BAL films closely resembled the composition of the initial natural apatite target. Finally, nanoindentation tests showed that PED could deposit LAB films with high mechanical properties.

Materials Letters, tom 137, 2014, strony. 260-264

simple novelin place ofFor the first time, a biomimetic strategy was used to rapidly induce bone-like nanoapatite in a chitosan matrix (CTS). Particles precipitated from the surrounding simulated body fluid in the polymer matrix during the hydrothermal process showed uniform distribution and excellent association with bone minerals. The excellent bone-binding properties and biocompatibility of bone-like apatite can provide a suitable environment for the attachment and ingrowth of MC3T3-E1 osteoblasts. The bioactive apatite membrane designed in this paper could make the new bone-like apatite/CTS matrix nanocomposite an attractive substitute for bone grafts and regeneration.

Materials Science and Engineering: C, Volume 70, Part 1, 2017, pp. 721-727

The interaction of amino acids (glycine, proline, lysine) with brushite-based bone cements was investigated using various techniques (FTIR spectroscopy, thermogravimetry-TG, scanning electron microscopy-SEM, mechanical properties studies) in order to explain the properties of the obtained composite materials and interactions occurring at the molecular level between the inorganic matrix and the organic residues. The brush phase is usually also obtained in the presence of amino acids added during the preparation of the bone cement. By focusing on glycine incorporation, the presence of a bulk glycine fraction that weakly interacts with the inorganic matrix can be predicted, along with glycine that specifically interacts with adsorption sites as indicated by FT IR and thermogravimetric data. In detail, the FT-IR data showed changes in the shape and position of the bands related to the stretching modes of the carboxyl groups in the glycine structure, which can be explained by the coordination of these functional groups with ions. womb. Heating this composite material at a controlled temperature causes the detection of condensation products, either a cyclic condensation product or a dipeptide. Scattered and non-specific H bonds appear to be the main mode of interaction of proline and lysine with bushite. Due to the coordination with the Ca ions described herein, glycine can act as a retarder during the preparation of brushite, which allows for good workability of the resulting compound.

Ceramics International, Volume 48, Issue 1, 2022, pp. 1326-1339

The use of eggshells to synthesize a value-added product such as nanocrystalline hydroxyapatite (HA) has attracted great interest from scientists as they are composed of CaCO₃with biologically essential trace elements such as Mg, Si,itp.. Various biomedical applications require HA with appropriate nanoscale properties such as crystallinity, particle size, morphology, surface area, mesoporosity,itp.. The same can be achieved by adjusting the reaction parameters, selecting the appropriate preparation mode and using organic modifiers. Here, we describe the rapid synthesis of eggshell-derived HA in the presence of various organic modifiers using a customized microwave reactor using previously optimized parameters. The synthesis process is relatively fast and takes 5 minutes. The absence of the organic modifier resulted in the formation of nanorods with heterogeneous sizes ranging from 40 to 600 nm. Ethylenediaminetetraacetic acid (EDTA) assisted synthesis yielded an HA-like flower of 1.67 ± 0.12 μm. While the synthesis assisted by polyethylene glycol 6000 (PEG) and cetyltrimethylammonium bromide (CTAB) yielded aggregated nanorods of 31±8 and 68±20 nm, respectively. In contrast, the synthesis with trisodium citrate dihydrate (TSC) resulted in HA needles with a typical length of 32±8nm. The presence of the trace elements Na, Mg and Si is confirmed by composition analysis. All samples were found to be mesoporous in nature. Hein vitroA cell culture experiment performed with the NIH 3T3 fibroblast cell line clearly demonstrated equal or higher cell viability for the samples synthesized in the presence of organic modifiers compared to the sample produced without the organic modifier. Therefore, based on the present study, we found that the synthesis of eggshell-derived HA using various organic modifiersByA customized microwave reactor could be a potential approach for the rapid preparation of precursor materials with nanoscale characteristics suitable for the development of bone fillers, drug/protein delivery vehicles, tissue engineering scaffolds,itp..

Chemistry and physics of materials, volume 143, number 3, 2014, pp. 1364-1371

Although stainless steel has good biocompatibility in most clinical cases, higher tissue response (bone binding properties) is required in the field of orthopedics. In this study, to improve the bonding ability of the stainless steel substrate to bone, a specific sequence of an osteocalcin mimic peptide is used as a bioactive coating material for biochemically modifying the surface of metal samples. This sequence consists of thirteen amino acids present in the first helix of osteocalcin, is synthesized in the amide form and physically adsorbed to the surface of 316LS (316 Low Carbon Surgical Grade) stainless steel substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to characterize the surface of peptide coated and uncoated substrates. The bioactivity and bone bonding capacity of coated and uncoated substrates are assessed by the level of hydroxyapatite formation by Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDS) and Scanning Electron Microscopy (SEM). The adhesion and proliferation of preosteoblastic cells is also assessed by the MTT assay. The results show that the surface of the coated sample is uniformly coated with the peptide and shows a rougher surface compared to the uncoated sample. TEM images reveal the formation of lamellar hydroxyapatite crystals in the presence of the peptide and the amorphous calcium phosphate phase without the peptide. The proliferation of pre-osteoblastic cells is significantly higher on the peptide-coated surface of the substrate, whereas cell adhesion is not affected by peptide coatings. Preosteoblastic cells also show a greater degree of spreading over the surface of the coated sample. Osteocalcin mimic peptide is believed to increase surface bioactivity and promote hydroxyapatite crystal formation and may lead to increased mineralization and bone formation on the surface of metal biomedical devices.

Organic electronics, volume 47, 2017, pp. 9-13

Non-geminated recombination was tested in TQ1: PC₆₁BM: PC₇₁BM (poly[[2,3-bis(3-octyloxyphenyl)-5,8-quinoxalinediylo]-2,5-thiophendiylo]:[6,6]-phenylo-C₆₁-butyric acid methyl ester:[6,6]-phenyl-C₇₁butyric acid methyl ester) using the extraction of photogenerated charge carriers using linear voltage amplification (photo-CELIV) and time of flight (ToF) techniques. The shapes of the photo-CELIV and ToF transients indicate purely unreduced Langevin recombination, while the decrease in photo-CELIV photogenerated charge carrier density indicates reduced third-order recombination. The marked discrepancy can be explained by the spatially separated holes and electrons in the lag time using the photo-CELIV method.