Human Serum Albumin Nanoparticles Fortumor Fluorescence/Photoacoustic Bimodalimaging And Dye Release Kinetics

The study of release kinetics of nanodrugs or probes is of great value in the analysis of therapeutic effect and bioavailability of nanodrugs.Currently,nanoparticles based on human serum albumin(HSA)have great potential for application in medical diagnosis and treatment,but there are few studies on the in vivo release kinetics of HSA probes or drugs and insufficient understanding.Based on this background,a pair of near-infrared cyanine dyes with F?rster resonance energy transfer(FRET)effect were coated by HSA,and Cy5/7@HSA nanoparticles were constructed,in which Cy BI5 was used as fluorescent donor(Ex 678 nm / Em 700 nm)and Cy BI7 as fluorescent receptor(Ex 818 nm / Em 845nm),which can be accurately tracked and monitored by fluorescence/photoacoustic dual-mode imaging.When the nanoparticles are complete,they show good FRET effect.When Cy BI5 or Cy BI7 are released from the nanoparticles,the FRET effect will be reduced.Therefore,by monitoring this process,we have successfully analyzed the dye release kinetics of HSA nanoparticles.In addition,the fluorescence probe based on FRET effect significantly increased stokes displacement,and the signal-to-noise ratio and sensitivity of fluorescence imaging were also greatly improved.The good photoacoustic effect of Cy5/7@HSA ensures that HSA nanoparticles can be accurately tracked in deep tissues by photoacoustic imaging,which greatly makes up for the lack of shallow penetration depth of single-mode fluorescence imaging.The specific content of this paper is summarized as follows:(1)Cy5/7@HSA nanoparticles were prepared by HSA using Cy BI5 and Cy BI7,two near-infrared dyes.The results of dynamic light scattering,electric potential and projection electron microscope show that the nanoparticles are homogeneous with negative charge at130 nm.The fluorescence spectrum and photoacoustic properties show that Cy5/7@HSA nanoparticles have good FRET effect and photoacoustic properties,indicating that they can be accurately tracked by FRET fluorescence/photoacoustic dual-mode imaging.In addition,FRET effect was used to monitor the release process of Cy5/7@HSA nanoparticles,and the effect of p H on the release of Cy5/7@HSA nanoparticles was studied.The results showed that acid condition accelerated the release of Cy5/7@HSA nanoparticles.(2)In this study,FRET effect was used to track the uptake and release of HSA nanoparticles at the cellular level.The results of subcellular co localization and endocytosis pathway analysis showed that Cy5/7@HSA nanoparticles first entered the cell throughcaveolin mediated endocytosis,and then entered the lysosome.After lysosome escape,the dye targets mitochondria.The results of fluorescence microscopy and flow cytometry showed that Cy5/7@HSA nanoparticles were the first to enter the cells with complete structure(strong FRET effect),Cy5/7@HSA released 100% Cy BI5 within one hour.The rapid release of Cy BI5 is attributed to the uptake of acid lysosomes and the p H sensitivity of Cy5/7@HSA nanoparticles.(3)In order to study the release kinetics of HSA nanoparticles in vivo,we used FRET fluorescence/photoacoustic dual-mode imaging to track Cy5/7@HSA nanoparticles in vivo.In vivo Experiment results of subcutaneous tumor model mice of breast cancer showed that the signal-to-noise ratio of NIR fluorescence imaging based on FRET was 5.2(twice the signal-to-noise ratio of ordinary fluorescence imaging channel)at 24 hours after injection,and the high-quality imaging results with the signal-to-noise ratio of 5.5 were still obtained at 48 hours,so the tumor area could be clearly visualized,while photoacoustic imaging could continue for 48 hours high resolution imaging of peripheral blood vessels can provide the specific distribution and diffusion process of Cy5/7@HSA NP in tumor internal blood vessels and tissues after intravenous injection.This shows that the nanoparticles can be tracked accurately for a long time by fluorescence/photoacoustic dual-mode imaging.Furthermore,the effect of p H on the release of HSA nanoparticles was analyzed by fluorescence imaging in Cy5/7@HSA tumor.The results showed that Cy5/7@HSA was closely related to local p H,and acidic environment was helpful to accelerate the release of Cy5/7@HSA nanoparticles.