Chloroquine-enhanced gene delivery mediated by carbon nanotubes

Polyethyleneimine-coated double-walled carbon nanotubes (DWCNTs) were used for dual gene and drug delivery, after loading the DWCNTs with the drug chloroquine, a lysosomotropic compound that is able to promote escape from the lysosomal compartment. Different forms of functionalization of the DWCNTs were examined in order to optimize this system. They included the testing of different treatments on DWCNTs to optimize the loading and delivery of chloroquine and the selection of a cationic polymer for coating the DWCNTs for optimum DNA binding and delivery. An acid oxidation treatment of DWCNTs was selected for optimum chloroquine loading together with polyethyleneimine as optimum cationic coating agent for plasmid DNA binding. Optimization of the conditions for choroquine-enhanced gene delivery were developed using luciferase expression as a model system. We have demonstrated that chloroquine-loading increases the ability of polyethyleneimine-coated DWCNTs to deliver functional nucleic acid to human cells. Cell viability tests have shown no cytotoxicity of the functionalized DWCNTs at the concentrations needed for optimum gene delivery. These results support the potential applications of this methodology in gene therapy

Effect of varying magnetic fields on targeted gene delivery of nucleic acid-based molecules

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The importance of high transfection efficiency has been emphasized in many studies investigating methods to improve gene delivery. Accordingly, non-viral transfection agents are widely used as transfection vectors to condense oligonucleotides, DNA, RNA, siRNA, deliver into the cell, and release the cargo. Polyethyleneimine (PEI) is one of the most popular non-viral transfection agents. However, the challenge between high transfection efficiency and toxicity of the polymers is not totally resolved. The delivery of necessary drugs and genes for patients and their transport under safe conditions require carefully designed and controlled delivery systems and constitute a critical stage of patients’ treatment. Compact systems are considered as the strongest candidate for the preparation and delivery of drugs and genes under leak free and safe conditions because of their low energy consumption, low waste disposal, parallel and fast processing capabilities, removal of human factor, high mixing capabilities, enhanced safety, and low amount of reagents. Motivated by this need in the literature, a platform for gene delivery via magnetic actuation of nanoparticles was developed in this study. The use of PEI-SPION (Super paramagnetic ironoxide nanoparticles) as transfection agents in in vitro studies was investigated with the effect of varying magnetic fields provided by a special magnetic system design, which was used as magnetic actuator offering different magnet's turn speeds and directions in the system. Results obtained from magnetic actuator systems were compared to the experiments without actuation and significant enhancement was observed in the transfection efficacies

Biophysical and biological contributions of polyamine-coated carbon nanotubes and bidimensional buckypapers in the delivery of miRNAs to human cells

Recent findings in nanomedicine have revealed that carbon nanotubes (CNTs) can be used as potential drug carriers, therapeutic agents and diagnostics tools. Moreover, due to their ability to cross cellular membranes, their nanosize dimension, high surface area and relatively good biocompatibility, CNTs have also been employed as a novel gene delivery vector system. In our previous work, we functionalized CNTs with two polyamine polymers, polyethyleneimine (PEI) and polyamidoamine dendrimer (PAMAM). These compounds have low cytotoxicity, ability to conjugate microRNAs (such as miR-503) and, at the same time, transfect efficiently endothelial cells. The parameters contributing to the good efficiency of transfection that we observed were not investigated in detail. In fact, the diameter and length of CNTs are important parameters to be taken into account when evaluating the effects on drug delivery efficiency. In order to investigate the biophysical and biological contributions of polymer-coated CNTs in delivery of miRNAs to human cells, we decided to investigate three different preparations, characterized by different dimensions and aspect ratios. In particular, we took into account very small CNTs, a suspension of CNTs starting from the commercial product and a 2D material based on CNTs (ie, buckypapers [BPs]) to examine the transfection efficiency of a rigid scaffold. In conclusion, we extensively investigated the biophysical and biological contributions of polyamine-coated CNTs and bidimensional BPs in the delivery of miRNAs to human cells, in order to optimize the transfection efficiency of these compounds to be employed as efficient drug delivery vectors in biomedical applications

Surface functionalization with polyethylene glycol and polyethyleneimine improves the performance of graphene-based materials for safe and efficient intracellular delivery by laser-induced photoporation

Nanoparticle mediated laser-induced photoporation is a physical cell membrane disruption approach to directly deliver extrinsic molecules into living cells, which is particularly promising in applications for both adherent and suspension cells. In this work, we explored surface modifications of graphene quantum dots (GQD) and reduced graphene oxide (rGO) with polyethylene glycol (PEG) and polyethyleneimine (PEI) to enhance colloidal stability while retaining photoporation functionality. After photoporation with FITC-dextran 10 kDa (FD10), the percentage of positive HeLa cells (81% for GQD-PEG, 74% for rGO-PEG and 90% for rGO-PEI) increased approximately two-fold compared to the bare nanomaterials. While for Jurkat suspension cells, the photoporation efficiency with polymer-modified graphene-based nanomaterial reached as high as 80%. Cell viability was >80% in all these cases. In addition, polymer functionalization proved to be beneficial for the delivery of larger macromolecules (FD70 and FD500) as well. Finally, we show that rGO is suitable for photoporation using a near-infrared laser to reach 80% FD10 positive HeLa cells at 80% cell viability. We conclude that modification of graphene-based nanoparticles with PEG and especially PEI provide better colloidal stability in cell medium, resulting in more uniform transfection and overall increased efficiency

Electrospun polyvinyl alcohol/carbon dioxide modified polyethyleneimine composite nanofiber scaffolds

A novel biocompatible polyvinyl alcohol/carbon dioxide modified polyethyleneimine (PVA/PEI-CO2) composite nanofiber was fabricated by a green and facile protocol, which reduces the cytotoxicity of PEI through the surface modification of the PEI with CO2. The 13C NMR spectrum, elemental analysis, and TGA show that CO2 has been incorporated in the PEI surface resulting in a relatively stable structure. The resulting PVA/PEI-CO2 composite nanofibers have been characterized by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), contact angle, and scanning electron microscopy (SEM). The results show that the average diameters of the nanofibers range from 265 ± 53 nm to 423 ± 80 nm. The cytotoxicity of PVA/PEI-CO2 composite nanofibers was assessed by cytotoxicity evaluation using the growth and cell proliferation of normal mice Schwann cells. SEM and the MTT assay demonstrated the promotion of cell growth and proliferation on the PVA/PEI-CO2 composite scaffold. It suggests that PEI-CO2 can have tremendous potential applications in biological material research

Effect of Retention Aids on AKD Size Response and Permanence

Poor size response and size reversion have been major concerns with the use of an alkyl ketene dimer (AKD) sizing system. Poor retention of calcium carbonate fillers and fiber fines are believed to be the cause of poor size response. A number of materials, including carbonate fillers, promoters and retention aids are believed to contribute to size reversion. The focus of this study was to determine the effectiveness of retention aids in obtaining good size response. Size permanence was also studied The performance of the retention aides were studied by preparing handsheets at five different zeta potentials. It was determined that when no retention aid was added to the system, size response was not dependent on zeta potential. It was dependent on the amount of polyethyleneimine (PEI) present in the system. Low sizing levels in the absence of PEI indicate poor retention of the size molecules. When cationic polymers were added to the stock, sizing levels showed a dramatic increase. This increase was do to superior retention of the fiber fines. As zeta potential was increased to highly cationic, size levels dropped due to poor retention of the sizing chemical. Cationic polymer was not observed to contribute to size reversion. Size response with the addition of an anionic polymer was highly dependent on the presence of a cationic fixative. When no PEI was present in the stock, the anionic polymer was ineffective. Small amounts of PEI provided cationic sites for the anionic polymer to bridge the fibers. Contrary to previous literature studies, the anionic polymer did not contribute to size reversion. When PEI was added to the system, large increases in sizing levels were observed PEI promotes excellent retention of the fiber fines. Good fines retention will increase sizing levels. Not only did PEI promote the reaction between AKD and cellulose, no size reversion was observed when it was used

Label-Free, Highly Sensitive Electrochemical Aptasensors Using Polymer-Modified Reduced Graphene Oxide for Cardiac Biomarker Detection

Acute myocardial infarction (AMI), also recognized as a ???heart attack,??? is one leading cause of death globally, and cardiac myoglobin (cMb), an important cardiac biomarker, is used for the early assessment of AMI. This paper presents an ultrasensitive, label-free electrochemical aptamer-based sensor (aptasensor) for cMb detection using polyethylenimine (PEI)-functionalized reduced graphene oxide (PEI???rGO) thin films. PEI, a cationic polymer, was used as a reducing agent for graphene oxide (GO), providing highly positive charges on the rGO surface and allowing direct immobilization of negatively charged single-strand DNA aptamers against cMb via electrostatic interaction without any linker or coupling chemistry. The presence of cMb was detected on Mb aptamer-modified electrodes using differential pulse voltammetry via measuring the current change due to the direct electron transfer between the electrodes and cMb proteins (Fe3+/Fe2+). The limits of detection were 0.97 pg mL???1 (phosphate-buffered saline) and 2.1 pg mL???1 (10-fold-diluted human serum), with a linear behavior with logarithmic cMb concentration. The specificity and reproducibility of the aptasensors were also examined. This electrochemical aptasensor using polymer-modified rGO shows potential for the early assessment of cMb in point-of-care testing applications

Development of anion-selective membranes

Methods were studied of preparing anion-exchange membranes that would have low resistance, high selectivity, and physical and chemical stability when used in acidic media in a redox energy storage system. Of the twelve systems selected for study, only the system that was based on crosslinked poly-4-vinylpyridinium chloride produced physically strong membranes when equilibrated in l M HCl. The resistivity of the best membrane was 12 ohm-cm, and the transference number for chloride ions was 0.81