New Lymphatic Imaging Platform Combines Nanoparticles with Microneedles

A research team has reported the development of a new lymphatic imaging platform that combines methylene blue nanoparticles with a dissolvable microneedle delivery system. The platform, tested in animal models, was reported to produce clearer images and higher signal intensity compared to existing methods. The findings were published in a 2026 advance article in the journal Burns & Trauma.

Research Team and Publication

The work was conducted by researchers from Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Jiao Tong University, and Shanghai Children's Medical Center. The study was published as an advance article in Burns & Trauma (DOI: 10.1093/burnst/tkaf067).

Technical Development of the Platform

The researchers encapsulated the clinically approved near-infrared dye methylene blue within an MPEG-PCL nanocarrier using a double-emulsion method. This process altered the physical properties of the dye:

Particle size increased from the sub-10 nanometer range of free methylene blue to approximately 99 nanometers.
The resulting nanoparticles exhibited a slightly negative surface charge, improved fluorescence, and greater stability in aqueous solution, resisting quenching.
In laboratory cell studies, the nanoparticle material demonstrated low cytotoxicity, caused less than 5% hemolysis, and was taken up and transported across lymphatic endothelial cells.

Microneedle Delivery System

To administer the tracer, the nanoparticles were integrated into a dissolvable microneedle array.

The microneedles were arranged in a 15 × 15 array and were reported to be mechanically strong enough to pierce skin.
In vitro testing indicated the microneedles released approximately 80% of their payload.
The delivery method targets the superficial dermal layer.

Reported Results from Animal Models

In animal models, the performance of the new platform, designated MPEG-PCL@ME, was compared to current standards, indocyanine green and free methylene blue. According to the study:

The platform generated clearer images of lymphatic vessels at the same tracer concentration. The reported signal intensity was at least three times higher than that of the comparison agents.

Leakage of the tracer around the imaging site was minimal.
Dominant lymphatic vessels and nodes were more readily identified.
The method visualized repeating segmental contractions along lymphatic vessels, suggesting an ability to capture functional behavior in addition to anatomical structure.
The tracer demonstrated satisfactory biosafety in vivo, with no obvious pathological changes reported in major organs and normal routine blood indices.

Context and Limitations of Current Methods

The lymphatic system is involved in several pathological conditions, including lymphedema, chronic inflammation, and impaired wound healing. Current clinical imaging tools for this system have recognized limitations:

Lymphoscintigraphy involves radiation exposure.
Magnetic Resonance Lymphangiography can be costly and may have limited resolution.
Indocyanine Green Fluorescence Imaging and conventional methylene blue imaging can be limited by factors such as poor lymphatic targeting, signal instability, and insufficient spatial or functional resolution.
Free methylene blue has a small particle size, tends to aggregate in water, and lacks strong lymphatic specificity. Its standard delivery via intradermal injection can be painful and operator-dependent.

Researcher Statements and Potential Implications

The researchers suggested their work addresses several barriers in lymphatic imaging, including weak targeting, signal instability, painful administration, and limited dynamic functional assessment.

They stated the study "turns a familiar clinical dye into a smarter lymphatic probe."

The researchers indicated that a portable, painless, and nonradioactive system for lymphatic visualization could, with further development and clinical translation, support earlier diagnosis of lymphatic dysfunction, better monitoring of conditions like lymphedema, and more precise assessment of disease processes linked to impaired lymph flow.

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