Figure 3: Optical and magnetic properties and stability of the MNP-gold hybrid NPs.
From: Multifunctional nanoparticles as coupled contrast agents
(a) Extinction spectra of MNPs successively coated with PL-PEG-COOH and PLH (black), and with gold nanoshells of various thickness, 1–2 nm (purple), 2–3 nm (orange) and 4–5 nm (blue). As the gold nanoshell thickness increases, the spectral intensity increases and the peak centre blue-shifts. (b) Magnetization as a function of magnetic field at room temperature for MNP (black) and MNP-gold (2–3 nm shell thickness) (red). The gold shell coating has negligible effect on the magnetic behaviour of MNPs. Insets show the absence of magnetic hysteresis and magnetic separation of MNP-gold NPs. (c) Photothermal stability of MNP-gold NPs in comparison with gold nanocages and nanorods. Extinction peak shifts as a function of laser fluence indicate that nanocages and nanorods start to quickly degrade at 5 mJ cm−2, whereas MNP-gold hybrid NPs remain stable against laser irradiation of approximately three times higher fluence. TEM images of nanocages and nanorods are shown as insets, scale bars are 50 nm.
