Molecular modeling to study dendrimers for biomedical applications

© 2014 by the authors; licensee MDPI; Basel; Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/4.0/). Date of Acceptance: 17/11/2014Molecular modeling techniques provide a powerful tool to study the properties of molecules and their interactions at the molecular level. The use of computational techniques to predict interaction patterns and molecular properties can inform the design of drug delivery systems and therapeutic agents. Dendrimers are hyperbranched macromolecular structures that comprise repetitive building blocks and have defined architecture and functionality. Their unique structural features can be exploited to design novel carriers for both therapeutic and diagnostic agents. Many studies have been performed to iteratively optimise the properties of dendrimers in solution as well as their interaction with drugs, nucleic acids, proteins and lipid membranes. Key features including dendrimer size and surface have been revealed that can be modified to increase their performance as drug carriers. Computational studies have supported experimental work by providing valuable insights about dendrimer structure and possible molecular interactions at the molecular level. The progress in computational simulation techniques and models provides a basis to improve our ability to better predict and understand the biological activities and interactions of dendrimers. This review will focus on the use of molecular modeling tools for the study and design of dendrimers, with particular emphasis on the efforts that have been made to improve the efficacy of this class of molecules in biomedical applications.Peer reviewedFinal Published versio

Binding properties of polyamidoamine dendrimers

ABSTRACT: Dendrimers are globular, hyperbranched polymers possessing a high concentration of surface functional groups and internal cavities. These unique features make them good host molecules for small ligands. To reveal relationships between dendrimer size and its encapsulating properties, the interactions of the fourth and the sixth generations of polyamidoamine dendrimers (PAMAM G4 and PAMAM G6) with a fluorescent dye 1-anilinonaphthalene-8-sulfonate (ANS) were studied. Because ANS is a fluorescent molecule and its fluorescence is very sensitive to changes in its microenvironment, it was possible to use spectrofluorometric methods to evaluate the interactions with dendrimers. A double fluorometric titration method was used to estimate a binding constant and the number of binding centers. There were two types of dendrimer binding centers characterized by different affinity towards ANS. For PAMAM G4, the values of K b and n for low-affinity and high-affinity sites equaled to 2.6 Â 10 5 , 0.60 and 3.70 Â 10 6 , 0.34, respectively, whereas in the case of PAMAM G6, these values equaled to 1.2 Â 10 5 , 76.34 and 1.38 Â 10 6 , 22.73. It was observed that the size of the dendrimer had a strong impact on the number of ANS molecules that interacted with dendrimers and their location within the macromolecule

Ultrasonic Formation of Fe3O4‑Reduced Graphene Oxide−Salicylic Acid Nanoparticles with Switchable Antioxidant Function

We demonstrate a single-step ultrasonic in situ complexation of salicylic acid during the growth of Fe3O4-reduced graphene oxide nanoparticles (∼10 nm) to improve the antioxidant and antiproliferative effects of pristine drug molecules. These nanoparticles have a precisely defined electronic molecular structure with salicylic acid ligands specifically complexed to Fe(III)/Fe(II) sites, four orders of magnitude larger electric surface potential, and enzymatic activity modulated by ascorbic acid molecules. The diminishing efficiency of hydroxyl radicals by Fe3O4-rGO-SA nanoparticles is tenfold higher than that by pristine salicylic acid in the electro-Fenton process. The H+ production of these nanoparticles can be switched by the interaction with ascorbic acid ligands and cause the redox deactivation of iron or enhanced antioxidation, where rGO plays an important role in enhanced charge transfer catalysis. Fe3O4-rGO-SA nanoparticles are nontoxic to erythrocytes, i.e., human peripheral blood mononuclear cells, but surpassingly inhibit the growth of three cancer cell lines, HeLa, HepG2, and HT29, with respect to pristine salicylic acid molecules

Evaluation of dendronized gold nanoparticles as siRNAs carriers into cancer cells

Gene therapy is one of the most promising approaches for potential application in the treatment of diseases, ranging from cancer and heritable disorders to infectious diseases. Before nucleic acid molecules can reach their site of action inside target cells, they must overcome several obstacles. Thus, to fully exploit the therapeutic potential of nucleic acids, efficient delivery systems are required. We herein evaluated gold nanoparticles (AuNPs) covered with cationic carbosilane dendrons as siRNA delivery systems. Detailed analysis of formation of AuNP:siRNA complexes using circular dichroism, zeta-potential, zeta-size, electron microscopy and gel electrophoresis was performed. The stability of complexes in presence of heparin and RNase was evaluated. Internalization of AuNPs and their complexes with siRNAs into cancer cells was estimated by ultrastructure analysis and confocal microscopy. The cytotoxicity of dendrons, AuNPs and their complexes with siRNAs on 4 cancer cell lines (Caco-2, HeLa, U937 and THP-1) was estimated. We concluded that dendronization of AuNPs is a promising way to develop siRNA carriers for anticancer gene therapyUniversidad de AlcaláMinisterio de Economía y CompetitividadComunidad de MadridJunta de Comunidades de Castilla-La ManchaEuropean Commissio

Dendritic glycopolymers based on dendritic polyamine scaffolds: view on their synthetic approaches, characteristics and potential for biomedical applications

In this review we highlight the potential for biomedical applications of dendritic glycopolymers based on polyamine scaffolds. The complex interplay of the molecular characteristics of the dendritic architectures and their specific interactions with various (bio)molecules are elucidated with various examples. A special role of the individual sugar units attached to the dendritic scaffolds and their density is identified, which govern ionic and H-bond interactions, and biological targeting, but to a large extent are also responsible for the significantly reduced toxicity of the dendritic glycopolymers compared to their polyamine scaffolds. Thus, the application of dendritic glycopolymers in drug delivery systems for gene transfection but also as therapeutics in neurodegenerative diseases has great promisePublikacja w ramach programu Royal Society of Chemistry "Gold for Gold" 2014 finansowanego przez Uniwersytet Łódzk

Ruthenium Dendrimers against Human Lymphoblastic Leukemia 1301 Cells

Ruthenium atoms located in the surfaces of carbosilane dendrimers markedly increase their anti-tumor properties. Carbosilane dendrimers have been widely studied as carriers of drugs and genes owing to such characteristic features as monodispersity, stability, and multivalence. The presence of ruthenium in the dendrimer structure enhances their successful use in anti-cancer therapy. In this paper, the activity of dendrimers of generation 1 and 2 against 1301 cells was evaluated using Transmission Electron Microscopy, comet assay and Real Time PCR techniques. Additionally, the level of reactive oxygen species (ROS) and changes of mitochondrial potential values were assessed. The results of the present study show that ruthenium dendrimers significantly decrease the viability of leukemia cells (1301) but show low toxicity to non-cancer cells (peripheral blood mononuclear cells—PBMCs). The in vitro test results indicate that the dendrimers injure the 1301 leukemia cells via the apoptosis pathway.Funding: This work was co-financed by the Project EUROPARTNER of Polish National Agency for Academic Exchange (NAWA) and Pl-SK 2019–2020 bilateral project -PPN/BIL/2018/1/00150; supported by the project “NanoTENDO” granted by National Science Centre, Poland under the M-ERA.NET 2 of Horizon 2020 programme, project No: 685451. This research was also supported by grants from CTQ2017-86224-P (MINECO), consortiums IMMUNOTHERCAN-CM B2017/BMD-3733, NANODENDMED II-CM ref B2017/BMD-3703 and Project SBPLY/17/180501/000358 Junta de Comunidades de Castilla-La Mancha (JCCM). CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008–2011, IniciativaIngenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund. Acknowledgments: N.S.d.O. wishes to thank JCCM for a predoctoral fellowship. This article is based upon work from COST Action CA17140 “Cancer Nanomedicine from the Bench to the Bedside” supported by COST(European Cooperation in Science and Technology)