2. Oxide film of Molybdenum is the type of
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Answer:
Molybdenum Oxide
Molybdenum oxide (MoOx) nanomaterials have gained significant interest for biomedical applications in the recent times because of their tunable localized surface plasmon resonance (LSPR) effects (13). This LSPR effects have been widely investigated for the PTT. This enhancement in the LSPR activity by MoOx nanomaterials is because of the intervalence charge-transfer modulation within diverse valence state of Mo (14). Studies show that the LSPR activity of MoOx nanomaterials can be tuned by altering their chemical compositions. In general, the surface of MoOx nanomaterials is coated with PEG to prevent aggregation and enhance their stability and solubility in the biological environments (15).
MoOx nanomaterials are efficient theranostic nanomaterials because of their ability to generate PTT and photoacoustic imaging (PAI) (16). Song et al. developed pH-dependent oxidation-mediated degradable MoOx nanosheets and showed their ability to function as both PAI and ultrasound contrast imaging agents for image-guided PTT. Moreover, they showed effective clearance from the biological system, limiting their nonspecific toxicology profiles in the biological system (17). The phase and the morphology of MoOx can have a significant effect over the PTT heat conversion efficiencies of the MoOx nanomaterials (18). Li et al. demonstrated that the MoO3 nanoclusters and nanorods have lower PTT heat generation efficacies compared with MoO2 nanoclusters. They have also demonstrated CT-imaging-guided PTT from MoO2 nanostructures. This high photothermal conversion efficiency from MoO2 nanomaterials (62.1%) is due to the induction of small polarons in oxygen-deficient MoO2 nanoclusters under NIR irradiation, which results in enhanced nonradiative electron relaxation (19). Studies also show that MoOx nanoparticles can be used as efficient PTT agents under NIR wavelengths (1064 nm). The higher wavelengths are beneficial because the higher wavelength energy sources have enhanced penetration depth, which improves the therapeutic prospects for deep tissue therapies. Yin et al. demonstrated NIR PTT activity by MoOx nanoparticles when excited at both 808 nm (NIR-I biowindow) and 1064 nm (NIR-II biowindow). Moreover, they also showed enhanced singlet oxygen/reactive oxygen species generation from MoOx nanoparticles when excited with 808 and 1064 nm lasers. Their results show a mild hyperthermic heat generation (43°C) when irradiated with 0.5 W/cm2 laser at NIR-II biowindows. These low powers can eliminate the tissue damage in the animals (20). This combinatorial dual PDT and PTT from a single material is beneficial and can avoid the use of harmful/toxicological agents to generate efficient therapeutic outcomes.
In another study, Bao et al. loaded camptothecin into the MoOx hollow nanospheres and used them for synergistic PAI-guided photothermal chemotherapy. The developed hollow MoOx nanoparticles had numerous mesopores that resulted in enhanced loading of camptothecin. Furthermore, the release of camptothecin was further controlled in response to the pH and the NIR irradiation. This synergistic hybrid nanomaterial served as an efficient multimodal therapeutics in the PANC-1 pancreatic tumors (21).