1 december 2011: bron: doi:10.1016/B978-0-12-374396-1.00071-4

Recent is een overzichtstudie gepubliceerd van PDT - Photo Dynamische Therapie met nanodeeltjes zoals de BBC al in 2005 een artikel daarover publiceerde. Onderaan staat het abstract van de studie met ook een deeplink naar het volledige studieverslag.

8 augustus 2005: Bron: BBC news

Britse onderzoekers is het gelukt om in laboratoriumproeven met de nieuwste nanotechnologie, zie ook verhaal van meneer H. onder ervaringsverhalen bij prostaatkanker kankercellen van binnenuit te vernietigen en tegelijkertijd gezonde cellen te sparen. Koolstof nanodeeltjes, microscopisch kleine deeltjes, werden ingebracht bij kankercellen nadat ze gekoppeld waren aan foliummoleculen. Door deze daarna te belichten met infrarood licht werden de kankercellen van binnenuit zodanig verhit dat ze verneitigd worden. Gezonde cellen namen de nanodeeltjes niet op en leden geen schade door het licht. Bij de klassieke PDT worden lichtgevoelige middelen gebruikt, bv. foscan, die in alle cellen, dus ook de gezonde cellen nestelen en daarom niet echt gemakkelijk zijn in de dagelijkse toepassing en eigenlijk alleen bij oppervlakkige tumoren worden gebruikt zoals mond- en keeltumoren, slokdarmkanker, en ook borstkanker en rectumkanker en dan ook pas na vaak drie, vier dagen in gesloten, donkere ruimte te hebben verbleven, al komen er steeds meer goede resultaten hierover naar buiten.

Nanotechnology kills cancer cells
Nanotechnology has been harnessed to kill cancer cells without harming healthy tissue. The technique works by inserting microscopic synthetic rods called carbon nanotubules into cancer cells.
When the rods are exposed to near-infra red light from a laser they heat up, killing the cell, while cells without rods are left unscathed. Details of the Stanford University work are published by Proceedings of the National Academy of Sciences.
Researcher Dr Hongjie Dai said: "One of the longstanding problems in medicine is how to cure cancer without harming normal body tissue. "Standard chemotherapy destroys cancer cells and normal cells alike. "That's why patients often lose their hair and suffer numerous other side effects. "For us, the Holy Grail would be finding a way to selectively kill cancer cells and not damage healthy ones."

Many in cell

The carbon nanotubules used by the Stanford team are only half the width of a DNA molecule, and thousands can easily fit inside a typical cell. Under normal circumstances near-infra red light passes through the body harmlessly. But the Stanford team found that if they placed a solution of carbon nanotubules under a near-infra red laser beam, the solution heated up to about 70C in two minutes. They then placed the tubules inside cells, and found they were quickly destroyed by the heat generated by the laser beam. Dr Dai said: "It's actually quite simple and amazing. We're using an intrinsic property of nanotubes to develop a weapon that kills cancer."
The next step was to find a way to introduce the nantubules into cancer cells, but not healthy cells. The researchers did this by taking advantage of the fact that, unlike normal cells, the surface of cancer cells is covered with receptors for a vitamin known as folate. They coated the nanotubules with folate molecules, making it easy for them to pass into cancer cells, but unable to bind with their healthy cousins. Exposure to the laser duly killed off the diseased cells, but left the healthy ones untouched.

Refined technique

The researchers believe it should be possible to refine the technique still further, for instance by attaching an antibody to a nanotubule to target a particular kind of cancer cell. They have already started work on tailoring the technique to target lymphoma in mice. Dr Emma Knight, of the charity Cancer Research UK, said: "Nanotechnology has a lot to offer biomedical science, and the results of this paper suggest yet another way in which it may help in the fight against cancer. "However, this work is still at a very early stage. The researchers have shown that near-infra red light can cause nanotubes to produce heat that can kill cancer cells. "But their work so far has focused on cells that have been grown in culture in the laboratory. "Further research will be crucial to see whether these effects can be reproduced in the more complex environment of a tumour and, ultimately, the human body."

Nanoparticles for Photodynamic Therapy

Source: Science Direct: doi:10.1016/B978-0-12-374396-1.00071-4 Click here for the full studyreport 

2.01 - Nanoparticles for Photodynamic Therapy

Y. Chenga, C. Burdaa

a Case Western Reserve University, Cleveland, OH, USA

Available online 26 October 2010.

 

Despite being a very young research field, nanoparticle-based photodynamic therapy (PDT) has developed explosively as a research field and many researchers currently contribute to its fast advancement. Multifunctional nanoparticles with versatile compositions hold great promise as photosensitizer delivery systems and as complementary components for PDT. They can overcome most of the shortcomings of first- and second-generation PDT reagents. As a drug delivery system, nanoparticles can efficiently transport hydrophobic photosensitizers in vitro and in vivo. They can help the drugs overcome the physiological and biological barriers and improve cell uptake. The important goals of nanoparticle-based PDT systems are to provide a reasonably long circulation time, specific targeting, PDT efficacy and, if possible, excretion or degradation. Another important aspect of nanoparticles in PDT applications is that they can act as the potential photosensitizers, which can generate reactive oxygen species and produce phototoxicity. In this chapter, the various existing approaches using nanoparticles for photodynamic therapy are summarized. The various challenges in this emerging field are also described.

Author Keywords: Biodegradable; Biodistribution; Drug delivery; Multifunctional nanoparticles; PDT; Photodynamic therapy; Photosensitizers; Reactive oxygen species; ROI; Targeting nanoparticles; Toxicity

Chapter Outline


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