Skin-safe nanophotosensitizers with highly-controlled synthesized polydopamine shell for synergetic chemo-photodynamic therapy.

Although photodynamic therapy (PDT) has been extensively studied as an established modality of cancer treatment, it still suffers from a few clinical limitations, such as skin phototoxicity and tumor hypoxia. To circumvent these hurdles, hollow silica mesoporous nanoparticles (HMSNs) loaded with photosensitizers were employed as the nanoplatform to construct multifunctional nanoparticles (NPs). Specifically, an ultra-uniform polydopamine (PDA) shell was highly controlled grown around HMSNs by photogenerated outwards-diffused 1O2, followed by conjugation of folic acid-poly(ethylene glycol) and chelation of Fe2+ ions. Thanks to the optimal thickness of light-absorbing PDA shell, the multifunctional NPs exhibited not only negligible skin phototoxicity but also efficient 1O2 generation and photothermal (PT)-enhanced •OH generation upon respective photoirradiation. Anti-tumor therapy was then performed on both 4 T1 tumor cells and tumor-bearing mice by the combination of 638 nm PDT and 808 nm PT-enhanced chemodynamic therapy (CDT). As a result, high therapeutic efficacy was achieved compared to single-modality therapy, with a cell inhibitory rate of 86% and tumor growth inhibition of 70.4% respectively. More interestingly, tumor metastasis was effectively inhibited by the synergetic treatment. These results convincingly demonstrate that our multifunctional NPs are very promising skin-safe PDT agents combined with CDT for efficient tumor therapy.

[Determination of the fluorine release of fluoride varnishes by neutron activation method].

OBJECTIVE: To determine the fluorine content in enamel before and after besmearing fluoride varnishes by neutron activation method. METHODS: A pair of mandibular deciduous central incisor teeth were chosen. One was removed, and the other was besmeared with fluoride varnishes and removed 24 hours later. The contents of fluorine were determined and analyzed statistically. RESULTS: The fluorine content in the enamel of the tooth besmeared with fluoride varnishes was higher than that in the control tooth (P < 0.05). CONCLUSIONS: The application of the fluoride varnishes can effectively increase the content of fluorine in the sclerous tissues.