Construction Of Rhodamine B And Cisplatin Functionalized Nanoparticles For Drug In Vivo Fate Study And Efficent Tumor Treatment

Nanomedicines can achieve high permeability and high retention(EPR)in the special tumor microenvironment due to their size effect.Compared with small molecule drugs,nanomedicines have obvious advantages and therefore show promise prospects in tumor treatment.The delivery efficiency and therapeutic effect of nanomedicine are closely related to its in vivo fate(e.g.pharmacokinetics and biodistribution).Therefore,studying the in vivo fate of nanomedicine is an essential part of the development of nanomedicine.Fluorescent dyes are the most commonly used for labeling nanomedicine in the basic research of nanomedicine.Most traditional nanomedicines load fluorescent dyes into the core through hydrophobic interactions,but this method has a big drawback,that is,fluorescent dyes will "burst release" after being injected into the body.The loaded dyes quickly separated from the nanocarrier and became free small molecules,which could not reflect the true in vivo fate of nanomedicine.The same problem also occurs in drug encapsulation.Drug molecules encapsulated through hydrophobic interactions are also occur to "burst release" in the body and become free molecules,thereby limiting the ultimate therapeutic effect of nanomedicine.To solve the above problems,we abandoned the traditional entrapment method and adopted a chemical method:We conjugated fluorescent dyes and drug molecules with polymers,and then the polymers were self-assembled into functional nanoparticles containing fluorescent groups or chemotherapeutic drug molecules on the surface,which respectively have the functions of fluorescent indication and tumor cell killing.In this paper,we aim to design functional nanoparticles for reliable fluorescent labeling and efficient tumor treatment.This paper is mainly divided into the following two parts:(1)In order to develop a method that can reliably and stably label nanomedicine,we first conjugated the fluorescent dyes Rhodamine B(RhoB)with the polymer polycaprolactone(PCL)to obtain PCL-RhoB,which is incorporated when prepare nanoparticles for fluorescent labeling.We found that the self-assembled nanoparticles can be stably labeled by incorporating PCL-RhoB into the nanoparticles.Only 1%of PCL-RhoB was released from the RhoB-labeled polymeric nanoparticles(RhoB-PNPs)in phosphate buffer within 12 hours,which suggested that the signal of PCL-RhoB can be used to represent the behaviors of polymeric nanoparticles both in vitro and in vivo.PCL-RhoB could be effectively extracted and quantitatively detected by ultra-high-performance liquid chromatography(UPLC)in various media,such as PBS,a cell culture medium containing 10%FBS(pH=7.4 and pH=6.8),mouse serum,simulated intestinal fluid and cell or tissue lysis.The intracellular contents of PCL-RhoB in MDA-MB-231 cells detected by UPLC were linearly correlated to the concentration of the RhoB-PNPs.In addition,the contents of PCL-RhoB in plasma and the spleen were proportional to the injected dose of RhoB-PNPs in vivo.As an application example,the pharmacokinetics and biodistribution of the nanoparticles over time in vivo were analyzed following intravenous injection to confirm the feasibility of this method.(2)Platinum-based chemotherapy as first-line treatment for lung cancers encounters insufficient selectivity,severe side effects and drug resistance in clinics.In this study,we developed an amphiphilic prodrug of cisplatin-poly(ethylene glycol)-block-polycaprolactone and demonstrated that the prodrug formed micellar nanoparticles,NPPt(?),with an average diameter of?100 nm.NPPt(?)released platinum in response to the intracellular acidic and reductive environment,and in turn induced significant antiproliferative activity in lung cancer cells.More importantly,NPPt(?)exhibited a prominent inhibitory effect on CD133+ lung cancer stem cells(CSCs)and suppressed tumor growth in vivo.Unlike cisplatin treatment which eventually enriches CSCs,NPPt(?)treatment prevents the accumulation of CD133+lung CSCs in tumors.Therefore,NPPt(?)simutaneously targeting CSCs and non-CSCs might represent a superior strategy to improve conventional anticancer therapy directed predominantly to tumor bulk populations.