Poly Allylamine Research Articles

Uptake and Transport of Novel Amphiphilic Polyelectrolyte-Insulin Nanocomplexes by Caco-2 Cells—Towards Oral Insulin

The influence of polymer architecture on cellular uptake and transport across Caco-2 cells of novel amphiphilic polyelectrolyte-insulin nanocomplexes was investigated. Polyallylamine (PAA) (15 kDa) was grafted with palmitoyl chains (Pa) and subsequently modified with quaternary ammonium moieties (QPa). These two amphiphilic polyelectrolytes (APs) were tagged with rhodamine, and their uptake by Caco-2 cells or their polyelectrolyte complexes (PECs) with fluorescein isothiocyanate-insulin (FITC-insulin) uptake was investigated using fluorescence microscopy. The integrity of the monolayer was determined by measurement of transepithelial electrical resistance (TEER), and insulin transport across the monolayers was determined. Pa and insulin were co-localised in cell membranes, while QPa complexes were found within the cytoplasm. QPa complex uptake was not affected by calcium, cytochalasin D or nocodazole. Uptake was reduced by co-incubation with sodium azide, an active transport inhibitor. Both polymers opened tight junctions reversibly, and insulin transport through monolayers increased when QPa or Pa was used. These APs have been shown to be taken up by Caco-2 cells and reversibly open tight cell junctions. Further work is required to optimise these formulations with a view to maximising their potential to facilitate oral delivery of insulin.

PEGylated Guanidinylated Polyallylamine as Gene-Delivery Carrier

A novel cationic co-polymer was developed by grafting poly(ethylene glycol) (PEG) on guanidinylated polyallylamine (PAA) for gene delivery. Characterization of PEG-g-guanidinylated PAA/DNA complexes demonstrated that particle size increased and surface charge decreased with increasing the amount of PEG. The results of cytotoxicity assay proved that grafted PEG could effectively decrease the cytotoxicity of the complexes. In transfection efficiency assay, HeLa cells treated with PEG(2)-g-guanidinylated PAA (formed with 17.5 μmol guanidinylated PAA and 2 μmol PEG)/DNA (0.2 μg EGFP plasmid) complexes showed a very high level of EGFP expression. In conclusion, combination of guanidinylation and PEGylation could effectively decrease the cytotoxicity and significantly increase the transfection efficiency of PAA.

Reversible chain association/dissociation via a CO2 responsive crosslinking/decrosslinking system

Reversible chain association/dissociation phenomenon via CO(2) responsive crosslinking/decrosslinking was detected in aqueous solutions of polyallylamine (PAA). The chain association/dissociation behavior was reversible and useful in the synthesis of porous crosslinked polystyrene, which suggested potential utility in the area of CO(2)-responsive separable adhesives, switches and sensors.

Formation and Characterization of Anionic Dye–Polycation Molecular Films by Layer-by-Layer Adsorption Process

Monolayer and multilayer films were formed by electrostatic self-assembly of poly (allyl amine) hydrochloride (PAH) and a strong fluorescent dye eosin Y (EY). In agreement with other published results, these compounds were found to form high-quality, closely packed monolayer and multilayer onto quartz substrate. The films formed on quartz substrate were then characterized in light of UV-Visible (UV-Vis) absorption spectroscopy and scanning electron microscopic (SEM) methods. Molecular movements were found to persist in the recently lifted layer-by-layer (LBL) films and about 72 h were required to get the film in stable condition. The photophysical characteristics of LBL films were found to vary with various parameters, such as number of deposited layers, dipping time in dye solution, pH of the PAH solution, and concentration of the dye. Both UV-Vis absorption spectroscopy and SEM studies also revealed the formation of molecular aggregates in the films.

Electrokinetic Study of Bovine Serum Albumin Adsorption on Previously Formed PAH/PSS Multilayer

Layer-by-layer structures (e.g. polyelectrolyte multilayers and protein-polyelectrolyte multilayers) play a very important role in surface modification processes. In the present study, electrokinetic measurements were applied for the investigation of poly(allylamine hydrochloride)/poly(sodium 4-styrenesulphonate) (PAH/PSS) multilayer formation, with PAH being a terminal layer, as a function of pH. Additionally, the effect of supporting electrolyte (KCl) concentration on multilayer formation was tested. Silica particles were used as the solid substrate. Furthermore, the adsorption of bovine serum albumin (BSA) on previously formed multilayer was examined as a function of pH and BSA concentration. It was confirmed that the electrokinetic measurements are suitable for monitoring the formation of various multilayers. In all investigated systems the process of multilayer formation was found to depend on conditions (ionic strength and pH) under which the multilayer was formed. Moreover, in the case of BSA, the adsorption on previously formed multilayer BSA concentration also plays a significant role.

Thin and Robust Encapsulation of Silver and Gold Nanoparticles with Dithiocarbamate-anchored Polyelectrolytes

ABSTRACTA robust, stable and thin primary amine functionalization is applied to gold and silver nanoparticles from poly(allylamine hydrochloride) (PAH) by converting a fraction of the amine groups in the polymer to dithiocarbamate (DTC) ligands, which absorb strongly onto noble metal surfaces. We observe marked improvements in the properties of gold nanospheres with a DTC-anchored rather than physisorbed PAH cap. The same level of improvement is not seen in silver nanoparticles, although it is clear from a distinct change in the plasmon spectrum in silver nanocubes that the DTC ligand does interact with the silver surface. In spite of their amine functionalization, both silver and gold particles show low cytotoxicity, possibly due to absorption of serum proteins forming a protective coating on the positively charged particle surface.

Functionalization of Calcium Carbonate Microparticles as a Combined Sensor and Transport System for Active Agents in Cells

In recent years colloidal particles and capsules, layer-by-layer (LbL) coated with biocompatible polyelectrolytes, have received much attention as drug-delivery systems. In this study an LbL-assembled, biopolymer-based multilayer system was established as a combined transporter and sensor for monitoring intracellular degradation and processing. CaCO3 cores were functionalized with fluorescein isothiocyanatelabelled poly(allylamine hydrochloride) (FITC-PAH). This pH-sensitive fluorescent dye allows identifying the location of these LbL-coated particles in cell compartments of different pH, like the endo-lysosome and cytoplasm. The labelled core was then coated with consecutive layers of protamine (PRM) and dextran sulfate (DXS). Finally, plasmid DNA (pEGFP-C1) as a reporter agent for drug release in the cytoplasm was integrated into the biocompatible and degradable PRM/DXS multilayer. The system was tested regarding its long-term stability and interaction with HEK 293T/17 cells. These multifunctional microparticles allow the simultaneous investigation of particle localization and processing within cells, and should thus provide a valuable tool for studying and improving the controlled LbL-based release of active agents into cells.

Cellularized alginate sheets for blood vessel reconstruction

Development of blood vessels remains a big challenge for vascular tissue engineering. We recently demonstrated that poly(allylamine hydrochloride)/poly(styrene sulfonate) (PAH/PSS) films are excellent substrates for vascular progenitor cell differentiation. However, no intact cell sheets could be harvested. Using a spraying procedure, we develop here a user-friendly technology for the development of small blood vessels based on alginate membranes. The key point of our approach is based on a multilayered PAH/PSS film built on micro-textured alginate gels, about 140 μm thick and which can be peeled off. The alginate, calcium chloride and polyelectrolyte solutions are sprayed on a vertical glass substrate. Due to the drainage of the calcium chloride solution on the adsorbed alginate layer, an oriented micro-textured gel is obtained. The PAH/PSS film, built on top of the gel, induces a good proliferation without phenotype alteration of smooth muscle cells. Parallel micro-textures on the top of the gel allow the orientation of cells. After peeling off the substrate, the cellularized membrane is rolled around a mandrel. Confocal microscopy observations show the formation of concentric layers with a presence of cells. This work represents the initial stages of a new, original blood vessel reconstruction strategy via tissue engineering.

Synthesis of Hydrogels from Polyallylamine with Carbon Dioxide as Gellant: Development of Reversible CO2 Absorbent

Hydrogels were successfully synthesized utilizing CO(2) as a gellant. A cross-linking reaction of polyallylamine (PAA) with CO(2) in the presence of 1,8-Diazabicyclo[5,4,0]-undec-7-ene (DBU) provided hydrogels bearing urea cross-linking points and residual amino groups in the side chains. The obtained hydrogels absorbed CO(2) at 25 °C and gave a maximum absorption four times larger than that of PAA aqueous solution and 2.8 times larger than that of the most commonly used absorbent, monoethanolamine. The PAA hydrogels desorbed the absorbed CO(2) completely under a N(2) atmosphere at 120 °C, and could be repeatedly recycled without loss of efficiency, indicating their potential application as recyclable CO(2) absorption materials.

Boron adsorption mechanism on polyvinyl alcohol

Recently, an increase in the use of boron compounds has led to an increase in boron emissions, and concern has grown regarding its detrimental effects on the human body. An adsorbent that adsorbs boron selectively has been developed as a countermeasure. Although certain commercially available boron selective adsorbents can be used to remove boron from aqueous solutions by utilizing the strong affinity between boron and hydroxyl groups, the adsorption capacity appears to be insufficient. So, we adopted polyvinyl alcohol (PVA), which contains many hydroxyl groups, as a model adsorbent. We investigated the boron adsorption characteristics of PVA, and then studied the relationship between the number of adsorption sites and actual adsorption amounts. We assessed the adsorption result by using adsorption site availability (ASA) as an indicator of the ratio of effectively functioning hydroxyl groups from the many hydroxyl groups in PVA. ASA was expressed as a percentage of the experimental equilibrium adsorbed amount in relation to the theoretical equilibrium adsorbed amount. We also compared the adsorption isotherms and ASA obtained with PVA, commercially available N-methylglucamine-type resin (CRB03 and CRB05) and the adsorbent we synthesized from polyallylamine (PAA) and glucose (PAA-Glu). Although PVA has many hydroxyl groups in a molecule, ASA analysis revealed that only 6% of the hydroxyl groups in PVA was used for boron adsorption. On the other hand, CRBs and PAA-Glu exhibited higher ASA values (about 15% and 35% respectively) and adsorption amounts, suggesting that the sterically congested adsorbent structure had a great influence on boron adsorption and ASA.

Optically Active Films Fabricated from Poly(Allylamine Hydrochloride) and R-(+)-1-Phenylethylamine Derivatives of Poly(Ethylene-Alt-Maleic Acid) with Different Degrees of Substitution

Optically active films were built up from poly(allylamine hydrochloride) (PAH) and R-(+)--phenylethylamine derivatives of poly(ethylene-alt-maleic acid) (PEMA-PEA) with substituting degrees (DS) ranging from 0.48 to 0.97. The growth of the film was monitored with the circular dichroism (CD) and the UV spectrophotometer and the effect of DS of PEMA-PEA on the film was investigated. UV and CD data show the growth regime of the multilayer changing from exponential to linear. Deposition amounts of PEMA-PEA in multilayer films decrease with the increase in DS of PEMA-PEA, which was explained based on the conformation of the polyelectrolyte and the charge overcompensation as the polyelectrolyte was deposited on the surface of the film. These results are of benefit to the development of multilayer films for the chiral separation of enantiomers.

Hybrid Polymer‐Grafted Multiwalled Carbon Nanotubes for In vitro Gene Delivery

Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymer-grafted multiwalled carbon nanotubes (MWNTs) (polymer-g-MWNTs) to efficiently complex and transfer plasmid DNA (pCMV-βGal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer-g-MWNTs as gene delivery systems, we first study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confirm pDNA binding to polymer-g-MWNT with different affinities, highest for PEI-g-MWNT and PEI/PAA-g-CNT constructs. β-galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modified LDH assay after 24 h incubation period. Additionally, PEI-g-MWNT and/or PEI/PAA-g-MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymer-g-MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer-g-MWNTs may be considered in the future as a versatile tool for efficient gene transfer in cancer cells in vitro, provided their toxicological profile is established.

Using jet mixing to prepare polyelectrolyte complexes: Complex properties and their interaction with silicon oxide surfaces

The influence of mixing procedure on the properties of polyelectrolyte complexes (PECs) was investigated using two complexation techniques, polyelectrolyte titration and jet mixing, the latter being a new method for PEC preparation. For the low-molecular-weight polyelectrolytes polyacrylic acid (PAA) and polyallyl amine hydrochloride (PAH), shorter mixing times produced smaller PECs, whereas for higher molecular weights of the same polyelectrolytes, PEC size first decreased with decreasing mixing time to a certain level, after which it started increasing again. This pattern was likely due to the diffusion-controlled formation of “pre-complexes”, which, in the case of low-molecular-weight polymers, occurs sufficiently quickly to form stable complexes; when polyelectrolytes are larger, however, non-equilibrium pre-complexes, more prone to aggregation, are formed. Comparing the techniques revealed that jet mixing produced smaller complexes, allowing PEC size to be controlled by mixing time, which was not the case with polyelectrolyte titration. Higher polyelectrolyte concentration during jet mixing led to the formation of larger PECs. It was also demonstrated that PEC size could be changed after preparation: increasing the pH of the PEC dispersion led to an irreversible increase in PEC size, whereas lowering the pH did not influence PEC size. The adsorption behavior of PECs formed from weak polyelectrolytes on model substrates was studied using QCM-D, SPAR, and AFM imaging; the results indicated that increasing the pH increased the amount of PECs adsorbed to model surfaces. However, the amount of PECs adsorbed to the model surfaces was low compared with other systems in all studied cases.

Core−Shell Diamond as a Support for Solid-Phase Extraction and High-Performance Liquid Chromatography

We report the formation of core-shell diamond particles for solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) made by layer-by-layer (LbL) deposition. Their synthesis begins with the amine functionalization of microdiamond by its immersion in an aqueous solution of a primary amine-containing polymer (polyallylamine (PAAm)). The amine-terminated microdiamond is then immersed in an aqueous suspension of nanodiamond, which leads to adsorption of the nanodiamond. Alternating (self-limiting) immersions in the solutions of the amine-containing polymer and the suspension of nanodiamond are continued until the desired number of nanodiamond layers is formed around the microdiamond. Finally, the core-shell particles are cross-linked with 1,2,5,6-diepoxycyclooctane or reacted with 1,2-epoxyoctadecane. Layer-by-layer deposition of PAAm and nanodiamond is also studied on planar Si/SiO(2) surfaces, which were characterized by scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA). Core-shell particles are characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), environmental scanning electron microscopy (ESEM), and Brunauer-Emmett-Teller (BET) surface area and pore size measurements. Larger (ca. 50 microm) core-shell diamond particles have much higher surface areas and analyte loading capacities in SPE than nonporous solid diamond particles. Smaller (ca. 3 microm), normal and reversed-phase, core-shell diamond particles have been used for HPLC, with 36,300 plates/m for mesitylene in a separation of benzene and alkyl benzenes and 54,800 plates/m for diazinon in a similar separation of two pesticides on a C(18) adsorbent.

Effect of the agglomeration of TiO 2 nanoparticles on their photocatalytic performance in the aqueous phase

TiO 2 nanoparticles have been widely explored as photocatalysts in the degradation of organic matters present in water. However, spontaneous agglomeration of TiO 2 nanoparticles in a suspension is a crucial issue that must be addressed before the photocatalyst can be used for water treatment. In the present work, the nature of the agglomeration of TiO 2 nanoparticles in aqueous suspension was investigated. Two approaches to minimize the agglomeration of colloidal TiO 2 particles were investigated. A careful control over the pH of the system was found to be an effective method for stabilizing colloidal TiO 2 particles and to significantly enhance the adsorption of orange II. As a result, the overall photocatalytic degradation rate was greatly accelerated. In addition to pH control, modification of TiO 2 particles using polyelectrolyte poly allylamine hydrochloride (PAH) was observed to be an effective approach for preventing colloidal TiO 2 particles from agglomeration.

Abstract 4343: X-ray detection of hepatocellular carcinoma (HCC) using gold nanoparticles conjugated to HCC-specific SF25 antibodies

Abstract There is widespread concern among health care professionals regarding the increase in HCC and the lack of optimal detection methods that lead to early diagnosis and treatment. It is hoped that early diagnosis may improve the prognosis of this almost uniformly fatal disease. There are substantial issues with false/negatives and false/positives and better, more specific and sensitive detection methods are urgently needed. For this reason, we aimed to design a novel detection method that is based on phase-sensitive x-ray imaging of gold nanoparticles, conjugated with HCC specific antibodies. Our laboratory has previously established various liver cancer specific antibodies by screening antigens that were uniquely present in the FOCUS hepatocellular carcinoma cell line. In the current study we used the SF25 antibody that is known to cross-react with a 125 kDa cell surface antigen. 10 nm gold nanoparticles were coated with polyacrylic acid (PAA) and poly(allylamine hydrochloride) (PAH), followed by conjugation with the SF25 antibody. The specificity of our antibody was confirmed in vitro by Western-blotting and immunoflurescence using FOCUS and NIH/3T3 cells (negative control). The gold labeling did not interfere with the immunofluorescent detection of SF25 antigen. The cellular localization of the SF25 protein was further confirmed by transmission electron microscopy. A labeling density of 10^4 gold particles per HCC cell was achieved. Given the sensitivity of the phase contrast imaging modality, this labeling density was also sufficient to enhance noticeably the density of subcutaneously raised HCC xenografts in vivo relative to healthy tissue. 10^7 cells were injected in the flanks of athymic nude mice. 1 week after inoculation the tumors were in vivo labeled by gold nanoparticle-conjugated SF25 antibodies. The gold content of these tumors were further quantified by x-ray fluorescence (XRF), which revealed gold fluorescence lines in the x-ray spectrum. These findings suggest that this imaging technique holds high in vivo potential for early detection of HCC. We envision that besides tumor detection, our x-ray imaging modality using nanoparticle-immunolabels will be useful for observing the delivery of drugs attached to or enclosed in nanoparticles. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4343.

Titania Opal and Inverse Opal Structures via Templating Polyelectrolyte Multilayer Coated Polystyrene Spheres

We report the construction of titania contained opal and inverse opal structures by using colloidal crystals as templates which were self assembled from poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA) multilayer film coated polystyrene (PS) particles. By infiltrating a titania precursor titanium (IV) bis (ammonium lactato) dihydroxide (TALH) into the polyelectrolyte (PE) multilayer film followed by calcination at different temperatures, PE/TiO2 composite opal or inverse opal structures were obtained. The thickness of the titania coating on colloidal crystals or the wall thickness of titania inverse opals could be controlled by varying the coating thickness of the PE film on PS particles during the layer-by-layer (LbL) deposition process. The crystalline phase of titania inverse opals was determined by the heating temperature. However, titania inverse opals with pure rutile phase lost their ordered structures due to the formation of large rigid rutile titania crystals during the phase transfer process. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), reflectance spectroscopy and X-ray diffraction were employed to characterize the formed structures and titania crystal phases.

Investigation of the influence of temperature on polyelectrolyte microcapsules containing and not containing proteins

Using the methods of light scattering and optical microscopy, data on the thermosensitivity of hollow microcapsules generated by alternative layers of poly(allylamine) and poly(sterenesulfonate) polyelectrolyte and microcapsules with included polyelectrolyte complexes and proteins have been obtained. It has been shown that all three types of capsules shrink with increasing temperature and the time interval of thermal influence, and their diameter decreases. The thermosensitivity has been estimated by means of the temperature factor of shell shrinkage (Ec). For all three types of the microcapsules containing from 6 to 10 layers in the shell, the phenomenon of the thermosensitivity alternation depending on the number of shell layers was revealed. With an odd number of the shell layers, the shrinkage is stronger than with an even number. Using the transport proteins of blood hemoglobin and bovine serum albumin as an example, the dependence of the thermosensitivity of microcapsules on the quantity, the degree of ionization, and the conformational state of the incapsulating protein was investigated.

Nanoporous Silica Polyamine Composites for Metal Ion Capture From Rice Hull Ash

Rice Hull Ash (RHA) was converted to amorphous silica gel using a modified version of published literature procedures. The gels were characterized by a comparison of their CPMAS [29] Si NMR and Scanning Electron Microscopy (SEM) images with commercial silica gels. The resulting gels were silanized with a 7.5:1 mixture of methyltrichlorosilane and chloropropyltrichlorosilane and then reacted with poly(allylamine) (PAA) to produce the silica polyamine composite (SPC) BP-1. The BP-1 was then further modified with pyridine-2-carboxaldehyde to form the copper selective SPC, CuSELECT. This procedure follows that used to produce the commercialized version of these composite materials from commercially available amorphous silica gels. The composites were characterized by solid state NMR techniques, elemental analysis, SEM, porosimetry, and metal ion capacity and selectivity. The overall goal of the project was to determine the feasibility of using RHA to make SPC. The observed strengths and weaknesses of this approach are discussed.

Adsorption kinetics and charge inversion in layer-by-layer films from nickel tetrasulfonated phthalocyanine and poly(allylamine hydrochloride)

Layer-by-layer (LBL) films of nickel tetrasulfonated phthalocyanine (NiTsPc) alternated with poly(allylamine hydrochloride) (PAH) have been prepared, whose surface charge has been evaluated using surface potential measurements. From adsorption kinetics results, we obtained the immersion time of ∼40 s, which was used to assemble layers of NiTsPc. The effect of gold (Au) and aluminum (Al) electrodes on the charge behavior was examined. We found that the surface potential (i.e. surface charge) was inverted each time a layer of PAH was alternated with another of NiTsPc molecules for the two types of electrodes, which was attributed to charge overcompensation between positive charges of PAH molecules, and negative charges from NiTsPc molecules.