| Cancer has become one of the most serious diseases that threaten human health, which become a major health concern to all mankind.Early diagnosis of cancer is difficult and chemotherapy is one of the most common clinical cancer treatment methods. Due to the non-selectivity of anticancer drugs to tumor tissues, drugs kill both tumor cells and normal cells during chemotherapy, resulting in adverse reactions and leading to poor patient compliance.And the evaluation of the treatment efficacy is not carried out until finishing a treatment cycle, probably missing the best time of the treatment. Therefore, looking for an efficient tumor treatment model might be helpful to realize individual administration, thus improving cancer therapeutic effect. The model could offer several advantages including specific killing of tumor cells and minimal damage to normal tissue; it could also achieve effective treatment of tumors while real-time monitoring the therapeutic responses, and timely adjust the dose, or type of administration according to monitoring results.Targeted delivery is a highly desirable strategy to improve the diagnostic imaging and therapeutic outcome because of enhanced efficacy and reduced toxicity.Using pharmaceutical methods, multifunctional nanocarriers can be prepared for simultaneous delivery of contrast agents and chemotherapy drugs with active targeting and tumor location triggered release properties, which can promote the development of the new strategy.Multifunctional nanocarrier is a kind of composite nanoparticles, which is prepared with the amphiphilic block copolymers with self-assembly technology, achieving an extended half-life, reduced side effects with tumor-targeting characteristics. Driven by such purposes, polymeric nanomicelles have emerged as a novel nanomedicine platform that demonstrated great potentials in anticancer drug delivery,and diagnostic imaging applications over the past decade.In this study, we designed and developed multifunctional nanocarriers to achieve several functions including the diagnosis and treatment of cancer, active targeting, tumor location triggered drug release, which could enable individual administration of the tumor and improve the therapeutic effect of anticancer drugs. Firstly, the polymeric nanomicelles were employed as the theranostics carriers. The novel pH sensitive amphiphilic block polymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)-poly(β-amino ester) (P123-PAE), the folate receptor targeting polymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)-folate (FA-P123), and polymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)-poly(β-amino ester-diethylene Triamine Pentacetic Acid-Gd P123-PAE-DTPA-Gd having a functional MRI were designed and prepared.Then, the chemotherapy drugs docetaxel (DTX) and curcumin (Cur) were selected as model drugs. The multifunctional polymeric nanomicelles, including pH-responsive polymeric nanomicelles, pH-responsive folate receptor mediated targeted polymeric nanomicelles (TPN), and targeted multifunctional polymeric nanomicelles (TMPN) were developed by self-assembly method. Finally, the basic properties, in vitro release behaviors, in vitro anti-tumor ability, in vivo anti-tumor ability, in vitro MRI properties, in vivo MRI properties were evaluated.This research laid the foundation to promote the development of individualized administration.The main methods and results of this study were exhibited as follows:1.Synthesis and characterization of multifunctional materialspH-responsive polymer consisting of P123 and PAE was synthesized through a Michael-type step polymerization. Then, the carboxyl group of FA and DTPA were reacted with the hydroxy group of P123 to obtain FA-P123 and P123-PAE-DTPA. The structures of all polymers were verified by NMR or UV.2. pH-responsive polymer nanomicellespH-responsive drug release seems a most significant strategies for cancer management. Nano-sized polymeric micelles based on P123-PAE block copolymer were prepared by self-assembly. When the media pH decreased from 7.4 to 5.5, the particle size of the micelles shrank from 152.5 nm to 122.1 nm due to the protonation of PAE blocks, and the zeta potential of the P123-PAE micelles changed from weakly positive (1.5 mV) to highly positive (9.0 mV) over a pH range from 7.4 to 5.5. Cur, a potential cancer therapy drug, was efficiently encapsulated into the P123-PAE micelles to enhance anticancer efficacy. The obtained Cur loaded P123-PAE micelles (Cur-P123-PAE) presented a spherical shape and high drug loading (14.2%). In vitro drug release studies demonstrated that the release rate of Cur was markedly influenced by pH. In vitro cytotoxicity tests showed that all the blank micelles were non-toxic. Cur-P123-PAE exhibited similar antitumor effect against MCF-7 and HepG2 cells compared to solubilized Cur solution. Using Coumarin-6 as a fluorescence probe, it was observed that Cur-P123-PAE experienced longer circulation followed by accumulation at tumor tissues with stronger fluorescence intensity. The results of pharmacokinetics studies showed that the P123-PAE micelles could significantly prolong the retention time of Cur in vivo.3.Folate receptor mediated pH-responsive polymer nanomicellespH-responsive folate receptor mediated targeted polymer nanomicelles (TPN) were developed in this study based on P123-PAE and FA-P123 copolymers. The obtained TPN presented a spherical shape and an average diameter of 105.5±10.64 nm. The synthesized nanomicelles were then investigated for DTX delivery. The DTX was loaded into the TPN with a decent drug loading content of 15.02±0.14 wt.%. In vitro drug release results showed that the DTX was released from the TPN at a pH-dependent manner. Tetrazolium dye (MTT) assay revealed that the bland polymer nanomicelles displayed almost nontoxicity at 200 μg/mL concentration. However, the DTX-loaded TPN showed high anti-tumor activity at low IC50(0.72 μg/mL) for MCF-7 cells following 48 h incubation. Cellular uptake experiments revealed that the TPN had higher degree of cellular uptake than non-targeted polymer nanomicelles, indicating that the nanomicelles were internalized into the cells via FA receptor-mediated endocytosis. Moreover, the cellular uptake pathways for the FA grafted polymer involved energy-dependent, clathrin-mediated and caveolae-mediated endocytosis. The cell killing effect and cellular uptake of the DTX-TPN by the MCF-7 cells were all enhanced by about two folds at pH 5.5 when compared to pH 7.4.The TPN also significantly prolonged the in vivo retention time for the DTX. These results from our study suggest that the biocompatible pH responsive folate-modified polymer nanomicelles present a promising safe nanosystem for intracellular targeted delivery of DTX.4. Multifunctional polymeric nanomicellesTo achieve theranostic and therapy of cancer, the targeted multifunctional polymer nanomicelles (TMPN) was prepared by added the Gd to the nanomicelles based on the targeted cancer therapy. The TMPN were prepared by self assembly method. The obtained TMPN presented a spherical shape and an average diameter of 164.50±7.26 nm nm. The synthesized nanomicelles were then investigated for DTX delivery. The DTX was loaded into the TMPN for study. In vitro drug release results showed that the DTX was released from the TMPN at a pH-dependent manner. MTT assay revealed that the bland polymer nanomicelles displayed almost nontoxicity.However, the DTX-loaded TMPN showed high anti-tumor activity than DTX-MPN for MCF-7 cells following 48 h incubation. Cellular uptake experiments revealed that the TPN had higher degree of cellular uptake than non-targeted polymer nanomicelles, indicating that the nanomicelles were internalized into the cells via FA receptor-mediated endocytosis.The results of in vivo tumor growth inhibition studies indicated that TMPN could efficiently inhibit the growth of tumors compared with MPN, suggesting that TMPN had excellent in vivo anti-tumor ability. The results of in vitro MRI studies showed that TMPN had high imaging intensity. After administration of TMPN,the tumor area exhibited brighter visual image. Meanwhile, the diagnosis time of TMPN was greatly prolonged. There results suggested that TMPN had desirable in vivo diagnosis ability. Considering these results, TMPN could realize the targeted release of drugs and imaging agents in tumor sites, thus increasing the diagnostic sensitivity and therapeutic efficacy.In summary, this study prepared a multifunctional nanocarriers to satisfy the diagnosis and treatment of cancer, active targeting, tumor location triggered release, this nanocarriers combined the molecular diagnostics and molecular treatment modalities, provied a new strategy of individualized dosing of the tumor, organic unity of diagnosis and treatment. |
PDF Full Text Request