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    Novel, nano-sized, liposome-encapsulated polyamidoamine dendrimer derivatives facilitate tumour targeting by overcoming the polyethylene glycol dilemma and integrin saturation obstacle. Li Gang,Song Yan-Zhi,Huang Zhen-Jun,Chen Kang,Chen Da-Wei,Deng Yi-Hui Journal of drug targeting Drug delivery systems (DDSs) commonly employ arginine-glycine-aspartic acid (RGD) peptides with polyethylene glycol (PEG)-dependent enhanced permeability and retention (EPR) effect to optimise tumour-targeting. However, the PEG dilemma and integrin saturation obstacle are major challenges. To address these issues, we constructed a novel, nano-sized DDS by encapsulating doxorubicin (DOX)-loaded folic acid derivatives of polyamidoamine dendrimer (PAMAM G5.0) in cyclic RGD-tyrosine-lysine pentapeptide (c[RGDyK])-modified liposomes (RGD-SL[FND/DOX]), prepared using thin-film hydration, film-dispersion and hydration-sonication. The liposomes were PEGylated, sterically stabilised and pH-sensitive. In vitro, RGD-SL[FND/DOX] showed pH-sensitive holistic FND/DOX release, and pH-dependent uptake and cytotoxicity in human cancer KB cells. At pH 7.4, RGD-SL[FND/DOX] demonstrated greater cellular uptake and cytotoxicity than relevant control formulations (except FND/DOX) did, although this advantage disappeared at pH 6.5. In vivo, RGD-SL[FND/DOX] inhibited S180 sarcoma xenografted tumour growth in Kunming mice more effectively than FND/DOX did. These findings demonstrate the feasibility of constructing double-stage tumour-targeting nano-sized DDSs such as RGD-SL[FND/DOX]. c[RGDyK] and the EPR effect, facilitated by the particle size (about 110 nm) and PEGylation, helped to target the DDS to the tumour tissue, while the subsequent pH-dependent release of FND/DOX and folic acid-mediated endocytosis specifically targeted the tumour cells, thereby overcoming the PEG dilemma and integrin saturation obstacle. 10.1080/1061186X.2017.1324860
    Folic acid-decorated polyamidoamine dendrimer exhibits high tumor uptake and sustained highly localized retention in solid tumors: Its utility for local siRNA delivery. Xu Leyuan,Yeudall W Andrew,Yang Hu Acta biomaterialia The utility of folic acid (FA)-decorated polyamidoamine dendrimer G4 (G4-FA) as a vector was investigated for local delivery of siRNA. In a xenograft HN12 (or HN12-YFP) tumor mouse model of head and neck squamous cell carcinomas (HNSCC), intratumorally (i.t.) injected G4-FA exhibited high tumor uptake and sustained highly localized retention in the tumors according to near infrared (NIR) imaging assessment. siRNA against vascular endothelial growth factor A (siVEGFA) was chosen as a therapeutic modality. Compared to the nontherapeutic treatment groups (PBS solution or dendrimer complexed with nontherapeutic siRNA against green fluorescent protein (siGFP)), G4-FA/siVEGFA showed tumor inhibition effects in single-dose and two-dose regimen studies. In particular, two doses of G4-FA/siVEGFA i.t. administered eight days apart resulted in a more profound inhibition of tumor growth, accompanied with significant reduction in angiogenesis, as judged by CD31 staining and microvessel counts. Tumor size reduction in the two-dose regimen study was ascertained semi-quantitatively by live fluorescence imaging of YFP tumors and independently supported antitumor effects of G4-FA/siVEGFA. Taken together, G4-FA shows high tumor uptake and sustained retention properties, making it a suitable platform for local delivery of siRNAs to treat cancers that are readily accessible such as HNSCC. STATEMENT OF SIGNIFICANCE:Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and is difficult to transfect for gene therapy. We developed folate receptor (FR)-targeted polyamidoamine (PAMAM) dendrimer for enhanced delivery of genes to HNSCC and gained in-depth understanding of how gene delivery and transfection in head and neck squamous cancer cells can be enhanced via FR-targeted PAMAM dendrimers. The results we report here are encouraging and present latest advances in using dendrimers for cancer therapies, in particular for HNSCC. Our work has demonstrated that localized delivery of FR-targeted PAMAM dendrimer G4 complexed with siVEGFA resulted in pronounced tumor suppression in an HN12 xenograft tumor model. Tumor suppression was attributed to enhanced tumor uptake of siRNA and prolonged nanoparticle retention in the tumor. Taken together, G4-FA shows high tumor uptake and sustained highly localized retention properties, making it a suitable platform for local delivery of siRNAs to treat cancers that are readily accessible such as HNSCC. 10.1016/j.actbio.2017.04.023
    Binding efficacy of tRNA with folic acid-PAMAM nanoparticles. Chanphai P,Tajmir-Riahi H A International journal of biological macromolecules tRNA binding efficacy to folic acid-PAMAM nanoparticles was determined, using multiple spectroscopic methods, thermodynamic analysis and transmission electron microscopy (TEM). The structural analysis showed tRNA binds folic acid-PAMAM through H-bonding, hydrophobic and van der Waals contacts. As PAMAM size increases the binding efficacy and the stability of tRNA conjugates are enhanced. TEM analysis showed major tRNA morphological changes, upon folic acid-PAMAM complexation. Folic acid-PAMAM nanoparticles can transport tRNA in vitro. 10.1016/j.ijbiomac.2018.03.181
    Doxorubicin-Conjugated PAMAM Dendrimers for pH-Responsive Drug Release and Folic Acid-Targeted Cancer Therapy. Zhang Mengen,Zhu Jingyi,Zheng Yun,Guo Rui,Wang Shige,Mignani Serge,Caminade Anne-Marie,Majoral Jean-Pierre,Shi Xiangyang Pharmaceutics We present here the development of multifunctional doxorubicin (DOX)-conjugated poly(amidoamine) (PAMAM) dendrimers as a unique platform for pH-responsive drug release and targeted chemotherapy of cancer cells. In this work, we covalently conjugated DOX onto the periphery of partially acetylated and folic acid (FA)-modified generation 5 (G5) PAMAM dendrimers through a pH-sensitive -aconityl linkage to form the G5.NHAc-FA-DOX conjugates. The formed dendrimer conjugates were well characterized using different methods. We show that DOX release from the G5.NHAc-FA-DOX conjugates follows an acid-triggered manner with a higher release rate under an acidic pH condition (pH = 5 or 6, close to the acidic pH of tumor microenvironment) than under a physiological pH condition. Both in vitro cytotoxicity evaluation and cell morphological observation demonstrate that the therapeutic activity of dendrimer-DOX conjugates against cancer cells is absolutely related to the DOX drug released. More importantly, the FA conjugation onto the dendrimers allowed a specific targeting to cancer cells overexpressing FA receptors (FAR), and allowed targeted inhibition of cancer cells. The developed G5.NHAc-FA-DOX conjugates may be used as a promising nanodevice for targeted cancer chemotherapy. 10.3390/pharmaceutics10030162
    In situ and in silico evaluation of amine- and folate-terminated dendrimers as nanocarriers of anesthetics. Carrasco-Sánchez Verónica,Vergara-Jaque Ariela,Zuñiga Matías,Comer Jeffrey,John Amalraj,Nachtigall Fabiane M,Valdes Oscar,Duran-Lara Esteban F,Sandoval Claudia,Santos Leonardo S European journal of medicinal chemistry The search for new nano-systems for targeted biomedical applications and controlled drug release has attracted significant attention in polymer chemistry, pharmaceutics, and biomaterial science. Controlled drug delivery has many advantages over conventional drug administration, such as reduction of side effects, maintaining a stable plasma level concentration and improving the quality of life of patients. In this study, PAMAM G5 dendrimers and PAMAM G5-folic acid conjugates (PAMAM G5-FA) are synthesized and characterized by mass spectrometry (MALDI-MS). Controlled release studies at different pH values show that PAMAM G5-FA is a good candidate as a carrier for tramadol and morphine, while mathematical modeling is conducted, suggesting that the release process is governed by a diffusion mechanism. In addition, using molecular dynamics simulations, we investigate the structural and energetic properties that facilitate the encapsulation of tramadol and morphine by unmodified and functionalized PAMAM-G5 dendrimers at low, neutral and high pH. Our results correlate well with experimental data, confirming that tramadol and morphine may be encapsulated both by functionalized PAMAM dendrimers and unmodified PAMAM. Moreover, the simulations further reveal that hydrogen-bond and electrostatic interactions govern the affinity the dendrimers for both drugs. This information is envisioned to prove useful for the encapsulation of other drugs and for the design of novel functionalized dendrimers. 10.1016/j.ejmech.2013.11.040
    Formulation of temozolomide-loaded nanoparticles and their targeting potential to melanoma cells. Jiang Guan,Li Ronghua,Tang Jianqin,Ma Yafeng,Hou Xiaoyang,Yang Chunsheng,Guo Wenwen,Xin Yong,Liu Yanqun Oncology reports The present study was carried out to prepare and evaluate a temozolomide (TMZ)-loaded polyamide-amine dendrimer (PAMAM)‑based nanodrug delivery system, and to explore its ability to target human melanoma (A375) cells in vitro. Firstly, PAMAM-PEG and PAMAM-PEG-GE11 were synthesized by substitution and addition reactions, and their products were identified and characterized by fourier transform-infrared (FTIR), proton nuclear magnetic resonance (1H-NMR) and transmission electron microscopy (TEM), as well as differential light scattering (DLS). Using fluorescein isothiocyanate (FITC)-modified PAMAM, we synthesized FITC-PAMAM, FITC-PAMAM-PEG and FITC-PAMAM-PEG-GE11. Fluorescence microscopy and flow cytometry were used to monitor the uptake of A375 cells of these three nanomaterials. Secondly, TMZ-PAMAM‑PEG‑GE11-HA drug complexes were prepared by ultrasonic emulsification, and their particle size, zeta potential and morphology were evaluated by DLS and TEM. Drug loading (DL) and encapsulation efficiency (EE) were assayed by ultraviolet spectrophotometry. Thirdly, we ascertained whether TMZ-PAMAM-PEG-GE11-HA conjugates could target A375 cells in vitro. The TMZ-PAMAM‑PEG‑GE11-HA nanodrug delivery system was successfully synthesized according to FTIR and 1H-NMR. Its mean particle size was 183.2 nm and zeta potential was -0.01 mV. It was a regular sphere with good uniformity. The EE of TMZ-PAMAM-PEG-GE11-HA was ~50.63% and DL ~10.4%. TMZ-PAMAM-PEG-GE11-HA targeted A375 cells in vitro. In conclusion, the TMZ-PAMAM‑PEG-GE11-HA nanodrug delivery system was successfully prepared, and demonstrated its potential for targeting A375 cells in vitro. This system enhanced the sensitivity of A375 cells to TMZ, and provided a novel targeted strategy for the treatment of metastatic melanoma. 10.3892/or.2016.5342