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Up-converting liposomes for phototherapy

Researchers at Leiden University have developed lipid vesicles capable of transforming low energy photons to high-energy photons. These high-energy photons can be used for example to activate anticancer prodrugs.

Phototherapy is an emerging field to activate anticancer prodrugs in cancer treatment. Light activation of anticancer prodrugs allows for delivering toxicity in a spatially and timely resolved fashion. At Leiden University for example ruthenium-based produgs attached to liposomes combine phototherapy with a cancer-targeting drug-delivery system.

The new invention consists in making lipid vesicles capable of transforming low-energy photons into photons of higher energy. Typically, red light from a commercial PDT laser (630 nm) is converted by the water-soluble upconverting vesicles into blue light (473 nm). The blue photons are generated locally and have enough energy to activate light-activatable prodrugs, which was impossible with red photons.

This technology is promising because red light penetrate deeper human tissue compared to blue light. Also, our upconverting liposomes work at much lower power (~200 mW, 1 compared to other upconversion techniques based on two-photon processes or upconverting nanoparticles. Low power is highly beneficial in phototherapy to avoid side effects such as tissue overheating.

Key benefits

  • Upconversion in water-based system
  • Allows high-energy prodrug activation with low energy, high-penetrating light
  • Vesicles are PEGylated thus long-circulatingCancer targeting built in
  • Works at low power


  • Phototherapy and photodynamic therapy
  • Light-activated chemotherapy
  • Bio-imaging

Development stage

  • Proof-of-concept studies has been performed
  • Lipid composition optimized for upconversion at 37°C

Luris reference number


Patent status

A patent application has been filed

Data available on request

A priority patent application has been filed. Confidential information can be shared upon request