Lymph node (LN) imaging is central to the diagnosis, staging, and management of cancer, infectious diseases, and immune-related disorders. Precise visualization of cellular and molecular events in LNs, including tumor cell dissemination, immune cell dynamics, and disease-associated biomarkers, provides critical information for clinical decision-making. Recent progress in nanobiotechnology has driven the development of advanced imaging probes that integrate seamlessly with modalities such as magnetic resonance imaging (MRI), positron emission tomography (PET), fluorescence imaging, ultrasound, and optoacoustic imaging. These nanoscale platforms offer improved contrast, enhanced targeting, multimodal functionality, and the capacity to track complex biological interactions within LNs. In this review, we summarize current advances in nanotechnology-based probes for LN imaging, with an emphasis on probe design, multimodal integration, and translational applications. We further discuss challenges in clinical translation and highlight future directions for nanobiotechnology in LN diagnostics and imaging-guided therapy. Collectively, these developments are reshaping our understanding of LN biology and advancing the precision of disease diagnosis and treatment.

The development of microenvironment-responsive nanoprobes has shown great promise for use in magnetic resonance imaging (MRI), with the advantage of significantly improved specificity and good biocompatibility. However, the clinical application of responsive probes is hampered by a lack of biological sensitivity for early molecular diagnostics and visualizing microenvionment of metabolism reprogramming in tumor progression. Here, we report on a dual-ratiometric magnetic resonance tunable (DMRT) nanoprobe designed by crosslinking different ratios of transferrin chelating gadolinium and superparamagnetic nanoparticles, complexed to a pH responsive biocompatible polymer. This dually activatable nanoprobe enables pH-dependent tumor microenvironment visualization, providing exceptional quantitative pathophysiological information in vitro and in vivo. When used in combination with dual-contrast enhancement triple subtraction imaging technique (DETSI), this smart nanoprobe guarantees the diagnosis of early-stage diseases. We envisage that this novel integrated nanoplatform will provide a new paradigm for the clinical translation of robust DMRT nanoprobes for early disease detection and staging, as well as microenvironment visualization and disease progression monitoring.