Two-photon microscopy (TPM) has become an indispensable tool in the life sciences, offering exceptional spatial resolution, deep tissue penetration, and low phototoxicity. It provides a revolutionary solution for long-term dynamic observation of living cells and tissues. This article systematically explains the working principles of TPM and reviews its applications in cutting-edge fields such as neuroscience, immunology, oncology, regenerative science and plant biology, highlighting its remarkable multidisciplinary adaptability. Building on this foundation, we further explore the breakthrough directions and future prospects for the development of this technology.

The increasing use of cerium oxide nanoparticles (CeO₂-NPs) has raised concerns regarding their environmental fate and biological effects in soil–plant systems. This review uses cerium oxide nanoparticles (CeO₂-NPs) as a mechanistically well-characterized case study to examine relationships among dose, chemical speciation, and plant responses, with emphasis on Ce³⁺/Ce⁴⁺ redox cycling and condition-dependent, nanozyme-like activity. We discuss how particle size, surface charge, Ce³⁺/Ce⁴⁺ ratio, and coating interact with rhizosphere processes, including organic acid complexation, phosphate-mediated CePO₄ immobilization, and potentially microbially mediated transformation, to influence effective root-surface exposure. The resulting particulate, ionic, and secondary transformation-product pools affect root uptake, vascular transport, redox homeostasis, metabolism, and hormone-associated signaling. Major limitations include weak causal links between rhizosphere speciation and bioavailability, insufficient separation of particulate and ionic contributions, limited integration of multi-omics with speciation data, and uncertain extrapolation from hydroponic to soil systems. Standardized exposure protocols, integrated XANES, spICP-MS, and imaging workflows, and long-term soil studies are therefore required. Other rare-earth nanomaterials are discussed only briefly to define the material-specific boundaries of the CeO₂-centered framework.

The flooded rice rhizosphere is a continuous reactive interface composed of sediment, porewater, root-surface oxic microdomains, and iron plaque, where redox processes and Fe cycling regulate Cd/As speciation, bioavailability, and plant accumulation. Engineered nanomaterials (ENMs) have shown potential for reducing Cd/As uptake in rice, but the coupled roles of microbial community responses, iron-plaque gating, and cross-interface elemental migration remain insufficiently integrated. This review synthesizes the current evidence on ENM transformation and partitioning at flooded rhizosphere microinterfaces, focusing on front-end speciation changes, root-surface retention, microbial functional regulation, and plant sequestration or transport. Correlative evidence suggests that rhizosphere microorganisms are associated with altered redox conditions, Fe cycling, As methylation potential, and metabolite secretion, which may influence Cd/As partitioning and cross-interface migration. However, direct causal validation of the complete ENM transformation–microbial response–Fe cycling–Cd/As flux–grain accumulation sequence within a single integrated system remains lacking. We further discuss how elevated CO₂, micro-/nanoplastics, Fe/DOM dynamics, and water management regimes may modify this framework, and we identify Sb as a theoretical boundary case because direct ENM–rice evidence remains limited. Finally, we highlight the need to integrate spatial tracing and imaging methods, including persistent luminescence tracing, LA-ICP-MS, NanoSIMS, and µ-XRF/µ-XANES, with metaomics to connect particle localization, microbial function, and contaminant fate.