Micro or nano: Evaluation of biosafety and biopotency of magnesium metal organic framework-74 with different particle sizes

In recent years, various particulate materials have played important roles in medical applications. However, nano- and micron-sized particles of the same material could exhibit distinct properties due to different particle sizes. This finding provided a simple and effective way to improve the biological applications of particulate materials. Therefore, as a highly promising member, the effect of the particle size change of the magnesium metal organic framework-74 (Mg-MOF74) was well worth evaluating. Here we firstly assessed the in vitro and in vivo toxicity of micron/nanoscale Mg-MOF74 (m-Mg-MOF74/n-Mg-MOF74) in detail. Our in vitro study revealed that compared to micron-sized subjects, n-Mg-MOF74 provided a wider range of safe concentrations. Furthermore, both micron/nanoscale Mg-MOF74 showed good biocompatibility and allowed all the rats under the treatment to survive through the expected experimental periods, with n-Mg-MOF74 still showing lower cardiotoxicity. These advantages of nanoscale Mg-MOF74 might benefit from its sustainable and balanced release of Mg2+ both inside and outside the cells. Based on the biosafety evaluation, advanced bio-functional assessments of m/n-Mg-MOF74 including early osteogenesis and angiogenesis were also performed. Similarly, the suitable dose groups of n-Mg-MOF74 achieved optimal early osteogenic promotion and angiogenic stimulation effects. Overall, our combined data delineated the toxicity and biological behaviors of Mg-MOF74 of different scales, and suggested nanoscale Mg-MOF74 as a better choice for future applications. This result revealed that particle size reduction might be a viable strategy to improve and expand medical applications of MOFs or other particulate materials.