As a PhD candidate who works with noble metal nanoparticles on a daily basis, I have some issues with their work.
1. How do they plan to get the particles to "naturally" accumulate in tumors without some sort of surface coating; specifically one incorporating some sort of tumor sensing molecule?
2. If the nanoparticle is coated with some other molecule, do they still expect "low-energy" electrons to punch through without trouble? How low is "low-energy" anyway? In my experience, when dodecanethiol is attached to a nanoparticle surface (which is very common as a generic molecule for the synthesis work) 200 KeV electrons have no problem punching through, but this coating is much less transparent to a 40-80 KeV electron beam.
3. How well do these particles absorb x-rays anyway? The surface plasmon resonance peak (i.e. the wavelength of EM radiation that it preferentially absorbs) typically occurs in the 300-800 nm range for these (noble metal) nanoparticles. If there isn't a great absorption peak here, how much adjacent tissue are we cooking?
It just seems preliminary to elevate this to "treatment" status when the article really doesn't do much to inspire confidence in the work.