Understanding and mitigating the toxicity of MXenes in emerging applications

MXenes, a versatile class of two-dimensional transition-metal carbides, nitrides, and carbonitrides, exhibit exceptional properties for applications in energy, catalysis, and biomedicine. However, their rapid advancement has outpaced understanding of their biological and environmental safety. Recent findings reveal that MXene cytotoxicity is dose-, composition-, and surface-dependent rather than inherent. Ti-based MXenes show conditional biocompatibility, while V- and Cr-based variants present higher risks due to ion release. Variations in synthesis routes, flake size, and surface terminations contribute to inconsistent toxicological data. Surface engineering, green synthesis, and polymeric functionalization have emerged as effective routes to mitigate toxicity. Yet, the lack of standardized testing frameworks limits reliable structure toxicity correlations. Integration of machine learning and nano-informatics offers a path to predictive toxicology and safe-by-design strategies. Embedding toxicity assessment early in development will be vital for regulatory acceptance. Ultimately, harmonizing performance with safety will ensure MXenes’ sustainable translation into biomedical and technological applications.