Novel near-infrared (NIR) responsive lipogel technology, based on a composite system, that delivers therapeutic agents in a controlled manner.
Novel near-infrared (NIR) responsive lipogel technology, based on a composite system, that delivers therapeutic agents in a controlled manner.

Drug delivery systems that take their cargo exactly where treatment is needed inside the body while minimizing systemic side effects is a ‘holy grail’ for modern medicine. Now a team of researchers have come up with a fully biodegradable smart composite that deliver drugs inside the body when triggered by a laser [Martín-Saavedra et al., Acta Biomaterialia 61 (2017) 54-65].

Many different approaches are being explored for drug delivery systems, particularly for anticancer treatments that cause unpleasant side effects. But the combination of heat-sensitive liposomes, inorganic nanoparticles that can transform near-infrared (NIR) radiation into heat, and a polymer matrix based on the natural protein fibrin sets apart the approach of Nuria Vilaboa and Francisco Martín-Saavedra.

“Our approach integrates liposomal technology, the first drug delivery system approved for clinical purposes, within ‘smart’ hydrogels that are responsive to NIR light,” they say.

First, the team from University Hospital La Paz-IdiPAZ, CIBER-BBN, University of Zaragoza, Trinity College Dublin, the Royal College of Surgeons in Ireland, Utrecht University, and University Medical Center Utrecht encapsulated the widely used anticancer drug doxorubicin into heat-sensitive liposomes – spherical vesicles made from fatty molecules known as phospholipids. Then the drug-loaded liposomes and hollow gold or copper sulfide nanoparticle transducers were incorporated into a fibrin hydrogel matrix. The combination produces an injectable, biodegradable biomaterial loaded with drug molecules and heat-sensitive nanotransducers.

After the gel is introduced into the body, where it polymerizes at body temperature, drug delivery can be triggered using NIR laser light, which is absorbed by the nanotransducers and transformed into heat. When the local heating surpasses the melting temperature of the liposomes, the drug cargo is released.

“By modulating the amount of laser energy deposited in the composite, the irradiation regime, the concentration of NIR-nanotransducers and the extent of irradiated area in the lipogel, the amount of released drug can be precisely defined,” they explain.

The approach is practical, the researchers believe, because NIR laser light can penetrate through several centimeters of biological tissue or be used together with optical fibers to target harder-to-reach tissue.

“Our technology could overcome the problems of composite drug delivery systems, which mostly depend on the degradation of the polymeric component, that in many cases leads to insufficient initial release or high overdose,” points out Vilaboa.

The researchers are now planning to carry out preclinical tests to determine whether the NIR-responsive lipogels can control tumor growth.