2023, Feng, Yanhuizhi, Wu, Di, Knaus, Jennifer, Keßler, Sascha, Ni, Bing, Chen, Zongkun, Avaro, Johnathan, Xiong, Rui, Cölfen, Helmut, Wang, Zuolin

Biocompatible and bio-active coatings can enhance and accelerate osseointegration via chemical binding onto substrates. Amorphous calcium phosphate (ACP) has been shown as a precursor to achieve mineralization in vertebrates and invertebrates under the control of biological macromolecules. This work presents a simple bioinspired Gelatin-CaPO₄ (Gel-CaP) composite coating on titanium surfaces to improve osseointegration. The covalently bound Gel-CaP composite is characterized as an ACP-Gel compound via SEM, FT-IR, XRD, and HR-TEM. The amorphous compound coating exhibited a nanometer range thickness and improved elastic modulus, good wettability, and nanometric roughness. The amount of grafted carboxyl groups and theoretical thickness of the coatings are also investigated. More importantly, MC3T3 cells, an osteoblast cell line, show excellent cell proliferation and adhesion on the Gel-CaP coating. The level of osteogenic genes is considerably upregulated on Ti with Gel-CaP coatings compared to uncoated Ti, demonstrating that Gel-CaP coatings possess a unique osteogenic ability. To conclude, this work offers a new perspective on functional, bioactive titanium coatings, and Gel-CaP composites can be a low-cost and promising candidate in bone regeneration.

2021, Keßler, Sascha, Reinalter, Elrike R., Ni, Bing, Cölfen, Helmut

The interplay between citrate concentration and total supersaturation on the growth of nickel hexacyanoferrate (NiHCF) nanocrystals is investigated. Herein, control over the crystallization conditions enables the precise tuning of the nanocrystal (NC) dimensions toward their self-assembly into colloidal mesocrystals with unique features. The exploration of the early stages of crystallization reveals insights into the controlled in situ assembly of preformed NCs. Our work introduces new concepts related to the synthesis of NiHCF NCs and colloidal mesocrystals as efficient and applicable catalysts. This is successfully demonstrated for the degradation of the organic contaminant caffeine.

2022, Keßler, Sascha

2020-11-19, Keßler, Sascha, Gonzalez-Rubio, Guillermo, Reinalter, Elrike R., Kovermann, Michael, Cölfen, Helmut

The citrate-assisted growth of nickel hexacyanoferrate (NiHCF) nanocubes was investigated. Control over the complexation of Ni²⁺ ions with citrate at different temperatures enabled fine tuning of the nanocrystal (NC) dimensions and their self-assembly into mesocrystals. Our results introduce new concepts towards the synthesis of NiHCF NCs, potentially applicable to other members of the Prussian blue analogues family.

2021-10-18, Keßler, Sascha, Reinalter, Elrike R., Schmidt, Johannes, Cölfen, Helmut

The tetramethylammonium hydroxide (TMAH)-controlled alkaline etching of nickel hexacyanoferrate (NiHCF) mesocrystals is explored. The alkaline etching enables the formation of hollow framework structures with an increased surface area, the exposure of active Ni and Fe sites and the retention of morphology. The ambient reaction conditions enable the establishment of a sustainable production. Our work reveals novel perspectives on the eco-friendly synthesis of hollow and colloidal superstructures for the efficient degradation of the organic contaminants rhodamine-B and bisphenol-A. In the case of peroxomonosulfate (PMS)-mediated bisphenol-A degradation, the rate constant of the etched mesoframes was 10,000 times higher indicating their significant catalytic activity.