Recently, Prof. Daxiang Cui and Dr. Chunlei Zhang from the School of Sensing Science and Engineering, SEIEE published a front cover paper titled “Biomimetic Self-Assembling Metal−Organic Architectures with Non-Iridescent Structural Coloration for Synergetic Antibacterial and Osteogenic Activity of Implants” at ACS Nano (Figure 1). The research was carried out by researchers from Shanghai Jiao Tong University, Zhejiang University School of Medicine, and Technion-Israel Institute of Technology.

Figure 1 Cover of Volume 16, Issue 10 ACS Nano

To date, a vast majority of metallic biomedical implants are made of titanium (Ti) and its alloys, owing to their biocompatible characteristics, mechanical properties, and excellent corrosion resistance. However, the formation of bacterial biofilms at the bone–implant interface on and around Ti implants has been particularly of concern as implant-associated infections frequently lead to the failure of the implants. Hierarchical material design principles in nature have evolved to optimize performance in achieving external visual effects and/or internal mechanical properties. Despite great progress in the understanding of hierarchical design principles, there are still huge gaps in mimicking the complex features of biological materials that could account for the rich variations in nature.

Herein, by rationally combining metal−carboxylate and metal−organophosphate coordination interactions, the researchers constructed Au₂₅(MHA)₁₈ (MHA, 6-mercaptohexanoic acid) nanocluster self-assembled structural color coating films and phytic acid (PA)−metal coordination complexes on the surface of titanium implants sequentially (Figure 2). This bioinspired strategy yielded non-iridescent structural coloration over a wide visible spectrum, significantly expanding the nature color palette which primarily produces coloration in the blue wavelength region.  The rational combination of hard and borderline metal ions (Lewis acids) in the heterometallic metal−carboxylate and metal−organophosphate networks enables the borderline divalent transition-metal release in labile borderline−hard coordination sites. These predictive and well-orchestrated architectures reveal an appealing prospect of the application for antibacterial and osteogenic functionalization of metal implants.

Figure 2 Schematic illustration of the bioinspired metal–organic coating strategy

The work was supported by National Key Research and Development Program of China (2017FYA0205301), the National Natural Science Foundation of China (82020108017, 81974340, and 81921002), the Startup Fund for Youngman Research at SJTU (18X100040050), and the Medical Engineering Cross Project of Shanghai Jiao Tong University (YG2021QN64 and ZH2018QNA61).

Paper URL: https://doi.org/10.1021/acsnano.2c06030