Evolution from Classical to Non-classical Aggregation-Based Crystal Growth of Calcite by Organic Additive Control

Biomineralization of calcium phosphates functionalized with hydroxyapatite-binding peptide

Functionalization of calcium phosphates with biomimetic peptides is a promising strategy to increase cellular response for bone tissue repair. In this work, biphasic calcium phosphate pellets were functionalized with the hydroxyapatite-binding peptide pVTK by dropping a suspension of the peptide on the pellet surface. The bioactivity tests were performed in vitro by using McCoy culture medium. Cytotoxicity tests were also performed to assess cell viability. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with field emission gun (FEG-SEM). The results showed that functionalization with the biomimetic peptide was most effective in inducing precipitation of bone-like apatite on the pellets surface, when compared to the control groups (two positive control groups and one negative control group). Cytotoxicity tests showed that all samples are biocompatible but the pellets with peptide showed the highest values of cell viability.

Microbial Diversity in Moonmilk of Baeg-nyong Cave, Korean CZO

The Baeg-nyong cave is a limestone cave which has been nominated as the first critical zone observatory (CZO) in South Korea. Moonmilk is a well-known speleothem composed of various carbonate minerals. To characterize moonmilk from the Baeg-nyong cave, we performed mineralogical analyses and applied high-throughput 16S rRNA gene sequencing to analyze the microbial communities, including bacteria and fungi, of dry and wet moonmilk samples. The results showed that the dry and wet moonmilk samples had different and atypical crystal structures, although they were predominantly composed of CaCO3. Furthermore, metagenomic data revealed that the dry and wet moonmilk samples collected from an oligotrophic environment had completely different bacterial communities when compared to the outside soil, and there was a difference in bacterial communities even between dry and wet moonmilk specimens. Fungal communities, however, did not differ significantly between dry and wet moonmilk samples. This study is the first metagenomic analysis of two different types of moonmilk with different physical properties and the first report on the microbial diversity of moonmilk from a cave in the first CZO in South Korea.

Comparing the efficacy of hydroxyapatite nucleation regulated by amino acids, poly-amino acids and an amelogenin-derived peptide

The efficacy of HAP nucleation regulated by amino acids, poly-amino acids and an amelogenin-derived peptide named QP5 was compared systematically. Poly-amino acids and QP5 regulated HAP nucleation and enamel remineralization more effectively.

Structural evolution of amorphous calcium sulfate nanoparticles into crystalline gypsum phase

Growth and orientation of nanocrystalline domains within fused ACS particles generate monocrystalline gypsum phase.

HPAM–HABS induced synthesis of a labyrinth-like surface of calcite via rhombohedral lattice growth from the nanoscale

A labyrinth-like structure is generated during the phase transformations from nano- to micron-sized via a terrace-ledge-kink growth model of a rhombohedral crystal.

α-Calcium Sulfate Hemihydrate Nanorods Synthesis: A Method for Nanoparticle Preparation by Mesocrystallization

The past decades have witnessed great advances in nanotechnology since tremendous efforts have been devoted for the design, synthesis, and application of nanoparticles. However, for most mineral materials such as calcium sulfate, it is still a challenge to prepare their nanoparticles, especially with uniform size and high monodispersity. In this work, we report a route to regulate the morphology and structure of α-calcium sulfate hemihydrate (α-HH) and successfully synthesize and stabilize its mesocrystals for the first time. The ellipsoidal mesocrystals in length of 300-500 nm are composed by α-HH nanoparticles arranged in the same crystallographic fashion and interspaced with EDTA. The time-dependent experiments indicate the α-HH aggregates evolve from irregular structure to mesocrystal structure with the subsequent growth of subunits and then partially fuse into single crystals. Disorganizing the mesocrystal structure before the emergence of fusion reaps α-HH nanorods in a length of 30-80 nm and a width of 10-20 nm with high monodispersion. This ingenious concept paves an alternative way for nanoparticle preparation and is readily extended to other inorganic systems.