生物谷報(bào)道：腫瘤細(xì)胞與正常細(xì)胞的耐熱程度不同，因此采用熱療治療腫瘤,，一直是科學(xué)家探索的方法之一,，傳統(tǒng)的方法采用加熱等方式，均無(wú)法達(dá)到有效的靶向治療,。實(shí)際上,，50年前，科學(xué)家也發(fā)現(xiàn)另外一個(gè)現(xiàn)象,，磁性納米顆粒在改變磁場(chǎng)的情況下,，能實(shí)現(xiàn)顆粒加熱的現(xiàn)象，稱(chēng)為特別吸引率（SAR）,。但是具有磁性的納米顆粒都是由金屬氧化物組成的,，如鐵的氧化物,，但這些氧化物無(wú)法被探測(cè)到，因此,，使研究成為難題,！
最新美國(guó)Dartmouth大學(xué)科學(xué)家巧妙構(gòu)思，在磁性的金屬氧化納米顆粒表面再覆蓋一層金屬離子,，形成一個(gè)復(fù)合的納米粒子,，通過(guò)磁性分子的導(dǎo)引，使納米顆粒集中到腫瘤位置,，然后改變磁場(chǎng),，使粒子發(fā)熱，殺死腫瘤細(xì)胞,。
Nanocomposite turns up the heat on cancer
Iron/iron oxide nanocomposite particles could be used to heat tumours and destroy them say scientists in the US. Ian Baker of Dartmouth College in New Hampshire and colleagues have found that iron particles have a large "specific absorption rate" and so produce lots of heat. The iron particles are then coated with iron oxide, which allows the nanoparticles to be observed using magnetic resonance imaging (MRI).
Scientists have known for 50 years that magnetic nanoparticles can heat up in an alternating magnetic field. However, the nanoparticles need to have a high specific absorption rate (SAR) if they are to be used for destroying tumours. A large SAR not only reduces the dose of nanoparticles required but also minimizes the region treated, so that the heat from the nanoparticles does not affect surrounding healthy tissue.
Iron oxide particles have been used to induce hyperthermia because of their excellent biocompatibility and their good SAR, which results in efficient heating. For clinical applications, scientists also need to be able to observe the nanoparticles in vivo before starting treatment. Superparamagnetic iron nanoparticles typically 4?nm across are used for imaging using MRI but the problem is that these particles are not very efficient for magnetic heating.
Baker and co-workers may now have overcome this dilemma – by using iron particles coated with iron oxide nanoparticles. The saturation magnetization of iron is more than twice that of an iron oxide particle so the SAR also doubles. But, since pure iron cannot be imaged using MRI, the researchers decided to coat it with a thin shell of iron oxide nanoparticles. They therefore have the best of both worlds: the high SAR of iron for heating and the iron oxide film for imaging.
The iron oxide coating also passivates the core iron particles, which are unstable and would otherwise oxidize.
The nanocomposite particles could be used to treat cancer in two ways. The first is to antibody-tag the nanoparticles and inject them into the bloodstream, where they will then find their way to the tumour. The second, which is more suitable for near-surface tumours (like neck tumours), is to directly inject the nanocomposites into the tumour.
Baker told nanotechweb.org that the production method is relatively simple and cheap, and that the nanoparticles produced are fairly uniform in size.
The team now plans to vary the particle size and work on developing different coatings for the particles. Next, the researchers hope to perform in vivo studies by directly injecting the nanoparticles into mice with tumours, as they have already done with iron oxide particles.
The work was published in Appl. Phys. Lett.
