Polyamidoamine Dendrimer G4 Research Articles

Low-intensity focused ultrasound-assisted dox-piperine amplified therapy on anaplastic thyroid carcinoma by hybird tumor-targeting nanoparticles

Therapies against anaplastic thyroid carcinoma (ATC) have been sticking in the predicament of multiple drug resistance (MDR). To address multiple drug resistance and promote therapeutic efficiency, we developed a novel nanoparticle with properties of spatial-temporally controlled release based on poly (amido amine) dendrimers-G4(PAMAM-G4) & Low-intensity focused ultrasound (LIFU) and synergistic killing effect by the combination of Dox and Piperine (PIP). We synthesized a core-shell-structured nanoparticle named [email protected] by thin film hydration-sonoseismic method, where the core was consisted of PAMAM-G4 encapsulating Dox and the shell was formed by IR780-PIP-co-loaded bilayer lipid membrane. The therapeutic efficacy and biosafety of nanoparticles were evaluated by cell experiments and xenograft tumor nude mouse model experiments. Data showed that, with the intervention by LIFU, tumor-targeting dual-drug-loaded nanoparticles termed as [email protected] exhibited superior therapeutic effect over non-tumor-targeting dual-drug-loaded nanoparticles termed as [email protected] and remarkable advantages over non-tumor-targeting Dox-loaded-only nanoparticles termed as PAMAM-Dox, both in vitro and in vivo. With the addition of IR780, [email protected] NPs showed reduced side effects caused by drug-leakage, enhanced tumor-specific therapeutic effects and granted praiseworthy PA imaging capacity. Moreover, [email protected] possesses sound biocompatibility and biosafety. [email protected] has yielded great prospects in future treatment of anaplastic thyroid carcinoma and the potential of visualized therapy.

Duplex of Polyamidoamine Dendrimer/Custom-Designed Nuclear-Localization Sequence Peptide for Enhanced Gene Delivery.

Background: Dendrimers are an attractive alternative to viral vectors due to the low cost of production, larger genetic insert-carrying capacity, and added control over immune- and genotoxic complications through versatile functionalization. However, their transfection rates pale in comparison to their viral counterparts, resulting in widespread research efforts in the attempt to improve transfection efficiency. Materials and Methods: In this work, we designed a synthetic diblock nuclear-localization sequence peptide (NLS) (DDDDDDVKRKKKP) and complexed it with polyamidoamine (PAMAM) dendrimer G4 to form a duplex for gene delivery. We conducted transmission electron microscopy, gel mobility shift assay, and intracellular trafficking studies. We also assessed its transfection efficiency for the delivery of a green fluorescent protein-encoding plasmid (pGFP) to NIH3T3 cells. Results: PAMAM dendrimer G4, NLS, and plasmid DNA can form a stable three-part polyplex and gain enhanced entry into the nucleus. We found transfection efficiency, in large part, depends on the ratio of G4:NLS:plasmid. The triplex prepared at the ratio of 1:60:1 for G4:NLS:pGFP has been shown to be more significantly efficient in transfecting cells than the control group (G4/pGFP, 0.5:1). Conclusions: This new diblock NLS peptide can facilely complex with dendrimers to improve dendrimer-based gene transfection. It can also complex with other polycationic polymers to produce more potent nonviral duplex gene delivery vehicles.

Targeting delivery of oxaliplatin with smart PEG-modified PAMAM G4 to colorectal cell line: In vitro studies

Abstract In this research, the anti-cancer efficacy of oxaliplatin (OX) was modulated using a nanocarrier system with enhanced targeting efficacy towards folic acid receptors (FAR) expressing colorectal cancer cells. Oxaliplatin was loaded into polyamidoamine dendrimers G4 (PAMAM) imprinted with polyethylene glycol (PEG) and folic acid (FA). The nano-complexes were characterized by FT-IR, 1H NMR, DSC, TGA, SEM, TEM, DLS and Zeta potential analyzer. Drug loading efficiency (34%) and in vitro drug release studies of PEG-PAMAM-FA-OX nano-complex showed higher drug release at acidic pH. Furthermore, in vitro investigation of nano-complex was carried out using cellular uptake (84.67 ± 1.98% for colorectal cancer cell line), MTT assay, flow cytometry assay and acridine orange staining, to ascertain the cell internalization efficiency, cell viability, apoptotic phase and morphology of dead cell, respectively. Less value of cell viability (18.39 ± 1.91%) and more value of late apoptotic phase (81.8%) were obtained for PEG-PAMAM-FA-OX nano-complex as a final synthetic system.

Synthesis of Polyamidoamine Dendrimer for Encapsulating Tetramethylscutellarein for Potential Bioactivity Enhancement.

The biomedical potential of flavonoids is normally restricted by their low water solubility. However, little has been reported on their encapsulation into polyamidoamine (PAMAM) dendrimers to improve their biomedical applications. Generation four (G4) PAMAM dendrimer containing ethylenediaminetetraacetic acid core with acrylic acid and ethylenediamine as repeating units was synthesized by divergent approach and used to encapsulate a flavonoid tetramethylscutellarein (TMScu, 1) to study its solubility and in vitro release for potential bioactivity enhancement. The as-synthesized dendrimer and the dendrimer–TMScu complex were characterized by spectroscopic and spectrometric techniques. The encapsulation of 1 into dendrimer was achieved by a co-precipitation method with the encapsulation efficiency of 77.8% ± 0.69% and a loading capacity of 6.2% ± 0.06%. A phase solubility diagram indicated an increased water solubility of 1 as a function of dendrimer concentration at pH 4.0 and 7.2. In vitro release of 1 from its dendrimer complex indicated high percentage release at pH 4.0. The stability study of the TMScu-dendrimer at 0, 27 and 40 °C showed the formulations to be stable when stored in cool and dark conditions compared to those stored in light and warmer temperatures. Overall, PAMAM dendrimer-G4 is capable of encapsulating 1, increasing its solubility and thus could enhance its bioactivity.

Click synthesis of a polyamidoamine dendrimer-based camptothecin prodrug.

In the present work we report on the click synthesis of a new camptothecin (CPT) prodrug based on anionic polyamidoamine (PAMAM) dendrimer intended for cancer therapy. We applied 'click' chemistry to improve polymer-drug coupling reaction efficiency. Specifically, CPT was functionalized with a spacer, 1-azido-3,6,9,12,15-pentaoxaoctadecan-18-oic acid (APO), via EDC/DMAP coupling reaction. In parallel, propargylamine (PPA) and methoxypoly(ethylene glycol) amine were conjugated to PAMAM dendrimer G4.5 in sequence using an effective coupling agent 4-(4,6-dimethoxy-(1,3,5)triazin-2-yl)-4-methyl-morpholinium chloride (DMTMM). CPT-APO was then coupled to PEGylated PAMAM dendrimer G4.5-PPA via a click reaction using copper bromide/2,2'-bipyridine/ dimethyl sulfoxide (catalyst/ligand/solvent). Human glioma cells were exposed to the CPT-conjugate to determine toxicity and cell cycle effects using WST-1 assay and flow cytometry. The CPT-conjugate displayed a dose-dependent toxicity with an IC50 of 5 μM, a 185-fold increase relative to free CPT, presumably as a result of slow release. As expected, conjugated CPT resulted in G2/M arrest and cell death while the dendrimer itself had little to no toxicity. Altogether, highly efficient click chemistry allows for the synthesis of multifunctional dendrimers for sustained drug delivery.

Click Hybridization of Immune Cells and Polyamidoamine Dendrimers

Immobilizing highly branched polyamidoamine (PAMAM) dendrimers to the cell surface represents an innovative method of enhancing cell surface loading capacity to deliver therapeutic and imaging agents. In this work, hybridized immune cells, that is, macrophage RAW264.7 (RAW), with PAMAM dendrimer G4.0 (DEN) on the basis of bioorthogonal chemistry are clicked. Efficient and selective cell surface immobilization of dendrimers is confirmed by confocal microscopy. Viability and motility of RAW-DEN hybrids remain the same as untreated RAW cells according to WST-1 assay and wound closure assay. Furthermore, Western blot analysis reveals that there are no significant alterations in the expression levels of signaling molecules AKT, p38, and NFκB (p65) and their corresponding activated (phosphorylated) forms in RAW cells treated with azido sugar and dendrimer, indicating that the hybridization process neither induced cell stress response nor altered normal signaling pathways. Taken together, this work shows the feasibility of applying bioorthogonal chemistry to create cell-nanoparticle hybrids and demonstrates the noninvasiveness of this cell surface engineering approach.

Transbuccal Delivery of CNS Therapeutic Nanoparticles: Synthesis, Characterization, and In Vitro Permeation Studies

This work utilized polyamidoamine (PAMAM) dendrimer G4.5 as the underlying carrier to construct CNS therapeutic nanoparticles and explored the buccal mucosa as an alternative absorption site for administration of the dendritic nanoparticles. Opioid peptide DPDPE was chosen as a model CNS drug. It was coupled to PAMAM dendrimer G4.5 with polyethylene glycol (PEG) or with PEG and transferrin receptor monoclonal antibody OX26 (i.e., PEG-G4.5-DPDPE and OX26-PEG-G4.5-DPDPE). The therapeutic dendritic nanoparticles labeled with 5-(aminoacetamido) fluorescein (AAF) were studied for transbuccal transport using a vertical Franz diffusion cell system mounted with porcine buccal mucosa. For comparison, AAF-labeled PAMAM dendrimers G3.5 and G4.5, and fluorescein isothiocynate (FITC)-labeled G3.0 and G4.0 were also tested for transbuccal delivery. The permeability of PEG-G4.5 (AAF)-DPDPE and OX26-PEG-G4.5(AAF)-DPDPE were on the order of 10(-7) - 10(-6) cm/s. Coadministration of bile salt sodium glycodeoxycholate (NaGDC) enhanced the permeability of dendritic nanoparticles by multiple folds. Similarly, a multifold increase of permeability of dendritic nanoparticles across the porcine buccal mucosal resulted from the application of mucoadhesive gelatin/PEG semi-interpenetrating network (sIPN). These results indicate that transbuccal delivery is a possible route for administration of CNS therapeutic nanoparticles.

PEGylated Polyamidoamine Dendrimers with Bis-Aryl Hydrazone Linkages for Enhanced Gene Delivery

Surface modification of polyamidoamine (PAMAM) dendrimers with polyethylene glycol (PEG) often results in the decrease in their buffering capacity, which is essential for gene transfer. In this work, bis-aryl hydrazone bond, which possesses protonatable pyridine and amines, was explored as a new linkage for PEGylation of PAMAM dendrimers. PEGylated polyamidoamine (PAMAM) dendrimer G4.0 conjugates with bis-aryl hydrazone (BAH) linkages were synthesized following a two-step procedure: activation of PAMAM dendrimer G4.0 and monofunctional methoxypolyethylene glycol amine (MW=5000 Da) with succinimidyl 4-hydrazinonicotinate acetone hydrazone (SANH) and succinimidyl 4-formylbenzoate (SFB), respectively, and coupling of SFB-activated PEG to SANH-activated G4.0 to generate PEGylated G4.0 with bis-aryl hydrazone linkages (G4.0-BAH-PEG). It was found that the incorporation of BAH linkages into the vector significantly enhanced the buffering capacity of the vector even with a high degree of PEGylation (42 PEG chains per dendrimer). G4.0-BAH-PEG conjugates could complex with DNA plasmid tightly at low weight ratios and display dramatically improved cytocompatibility. According to gene transfection studies in 293T and HN12 cells, this new vector has been shown to be capable of both transfecting more cells and inducing higher gene expression than the parent dendrimer. This work demonstrates that the use of the BAH linkage in coupling of PEG to the dendrimer helps maintain or increase the buffering capacity of the functionalized dendrimer and results in enhanced transfection.

Synthesis and characterization of gold nanocomposites with modified and intact polyamidoamine dendrimers

Preparation and characterization of nanocomposites of gold nanoparticles (AuNPs) using 3rd and 4th generation of poly(amidoamine) dendrimers (PAMAM) and modified PAMAM were studied. By utilizing poly-(ethylene glycol) grafted PAMAM G3 (PEG-G3), 9.7 ± 3.1 nm gold particles were obtained; compared to particles of 15.4 ± 7.3 nm size stabilized by unmodified PAMAM G3 dendrimers. In order to decrease the size of the synthesized gold nanoparticles the quaternization of primary amines in the periphery of PAMAM G4 (QG4) dendrimer was suggested. Characterization of the structures by fluorescence spectroscopy, UV-Vis spectrometry and transmission electron microscopy (TEM) revealed that PEG-G3 was better than PAMAM G4 as a templating agent, and that the QG4 dendrimer produced gold nanoparticles with the smallest size and the lowest polydispersity. The average size of gold nanoparticles protected by PAMAM G4 and QG4 were 13.9 ± 4.5 and 6.1 ± 1.6 nm, respectively.