| objective: To synthesize a kind of novel multifuncti onal theranostic nanoprobe,melanin-loaded phase-transition nan oprobe(PTX-MEL-PFP-NPs);To investigate their properties of optics,physics,ultrasound,PTT,and biosafety;To observe the enhancement effect for ultrasound imaging and photoacoustic i maging,to investigate the feasibility of these microcapsules as a mu lti-modality imaging agents;To observe the drug delivery and the efficacy of PTT combined with chemotherapy in MDA-MB-231 in vitro.Methods: PTX-MEL-PFP-NPs were prepared by m ultistepemulsion evaporation method.The surface structure and morphology,Zeta potential distribution and the size the conc entration of melanin,PTX loading in PLGA nanoprobe,and t he UV-vis-NIR absorption spectrum were detected by the lig ht microscope(LM),scanning electron microscope(SEM),UV-v is-NIR spectrophotometer and transmission electronmicroscope(TEM).The Di I labeled PTX-MEL-PFP-NPs,which were prepared using the same process were incubated with MDA-MB-231 cells fo r different hours(1 h,3 h,6 h),then the phagotrophic effect of th ese microcapsules in MDA cells was observed by LSCM.808 NIR l aser-induced heat generation of PTX-MEL-PFP-NPs with differ ent concentrations and different laser power densities were ob served.Plot of temperature change of PTX-MEL-PFP-NPs solu tion irradiated by an 808 nm laser for four on/off cycles.In vitro release profile of paclitaxel from PTX-MEL-PFP-NPs in sustained-released medium with laser irradiation and without ir radiation by high performance liquid chromatography(HPLC).The cytotoxicity of PTX-MEL-PFP-NPs on the MDA-MB-231 and HUVEC was detected by CCK8 assay.In vitro cell viabil ity and apoptosis of MDA-MB-231 incubated with different N Ps(PTX,PTX-MEL-NPs,PTX-MEL-PFP-NPs)with or without las er irradiation was observed by CCK8 and FCM assay.Resul ts: The PTX-MEL-PFP-NPs were synthesized successfully,the nanoparticles were dispersed,spherical and uniform,w ith aver age particle size of(290.5±35.4)nm and zeta potential was(-10.5±6.8)m V.A lot of melanin particles distributed in PTX-MELPFP-NPs were observed under transmission electron microscop e(TEM).The loading efficiency of PTX in the PTX-MEL-PFP-NPs was(69.98±5.67)%,and the PTX encapsulation efficiency w as(6.65±3.67)%.The accumulative release of PTX from trigger ed by NIR light was measured by(53.15±4.2)% at the time p oint of 2d,which was almost 2-fold of that without NIR light.The photothermal effect of PTX-MEL-PFP-NPs could increase with nanoprobe concentration and radiant energy.After NIR li ght irradiation,the phase-transition of PTX-MEL-PFP-NPs occ urred and the ultrasonic signal intensity enhanced.Photoacoust ic signal in vitro,PTX-MEL-PFP-NPs showed a strong photoa coustic signal,and the intensity increased with the rising of n anoparticles concentration.After incubation with PTX-MEL-PF P-NPs for 5h,a lot of nanoparticles were observed in the cyt oplasmic.CCK8 assay in vitro,MEL-PFP-NPs exhibited negli gible toxicity to cells at tested concentrations(0 –3.2mg/m L),s uggesting that PLGA,melanin and PFP had good security and biocompatibility;With PTX-MEL-PFP-NPs and NIR light irradia tion,the viability of MDA-MB-231 cells was lowest and the apoptosis rate of MDA-MB-231 cells was highest.Conclusio n:PTX-MEL-PFP-NPs have been successfully synthesized;these nanoparticles have excellent size distribution,high encapsulation efficiency,photothermal conversion,biosafety and biocompatibi lity.PTX-MEL-PFP-NPs can be successfully acted as dual-mo dality biological imaging contrast agents for US and PAI ima ging in vitro.Further,we demonstrated that PTX-MEL-PFP-N Ps could respond to NIR light to trigger the drug release.Th e therapeutic studies demonstrated that PTX-MEL-PFP-NPs sho wed the synergetic effect over the cell killing in vitro and la y a foundation for in vivo research,photothermal therapy,drug delivery and synergistic HIFU. |
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