Diethylaminoethyl Groups Research Articles

Synthesis of guanidinium‐dendrimer‐type pDNA carriers for gene delivery into floating blood cells

AbstractGuanidinium‐dendrimer‐type pDNA carriers have been synthesized for gene delivery into floating blood cells. A 2nd generation polyamidoamine (PAMAM‐G2) dendrimers were modified with guanidinium groups at the primary amine. The resulting PAMAM‐G2‐Gu dendrimer with a modification degree of 53 mol%, PAMAM‐G2‐Gu(53), formed polyion complexes (PICs) above a mixing positive/negative charge ratio (+/−) of 64. The resulting PAMAM‐G2‐Gu(53)/pDNA PIC was stable for 24 h in the presence of 10% fetal bovine serum and exhibited no significant cytotoxicity against HL‐60 human leukemia cells during the above incubation. It is worth noting that the PAMAM‐G2‐Gu(53)/pDNA PIC at mixing positive/negative (+/−) charge ratio of 64 mediated the highest gene expression among all PICs in this study such as an unmodified PAMAM‐G2, the PAMAM‐G2 modified with diethylaminoethyl groups (PAMAM‐G2‐DEAE). Especially, the resulting gene expression was higher than commercially available branched poly(ethylenimine) (b‐PEI). Consequently, the PAMAM‐G2‐Gu(53)/pDNA PIC is effective for gene delivery to floating blood cells and is expected to be applied to ex vivo transfection.

DEAE/Catechol-Chitosan Conjugates as Bioactive Polymers: Synthesis, Characterization, and Potential Applications.

This work provides the first description of the synthesis and characterization of water-soluble chitosan (Cs) derivatives based on the conjugation of both diethylaminoethyl (DEAE) and catechol groups onto the Cs backbone (Cs-DC) in order to obtain a Cs derivative with antioxidant and antimicrobial properties. The degree of substitution [DS (%)] was 35.46% for DEAE and 2.53% for catechol, determined by spectroscopy. Changes in the molecular packing due to the incorporation of both pendant groups were described by X-ray diffraction and thermogravimetric analysis. For Cs, the crystallinity index was 59.46% and the maximum decomposition rate appeared at 309.3 °C, while for Cs-DC, the values corresponded to 16.98% and 236.4 °C, respectively. The incorporation of DEAE and catechol groups also increases the solubility of the polymer at pH > 7 without harming the antimicrobial activity displayed by the unmodified polymer. The catecholic derivatives increase the radical scavenging activity in terms of the half-maximum effective concentration (EC50). An EC50 of 1.20 μg/mL was found for neat hydrocaffeic acid (HCA) solution, while for chitosan-catechol (Cs-Ca) and Cs-DC solutions, concentrations equivalent to free HCA of 0.33 and 0.41 μg/mL were required, respectively. Cell culture results show that all Cs derivatives have low cytotoxicity, and Cs-DC showed the ability to reduce the activity of reactive oxygen species by 40% at concentrations as low as 4 μg/mL. Polymeric nanoparticles of Cs derivatives with a hydrodynamic diameter (Dh) of around 200 nm, unimodal size distributions, and a negative ζ-potential were obtained by ionotropic gelation and coated with hyaluronic acid in aqueous suspension, providing the multifunctional nanoparticles with higher stability and a narrower size distribution.

Dextran and Its Derivatives: Biopolymer Additives for the Modulation of Vaterite CaCO3 Crystal Morphology and Adhesion to Cells

AbstractNowadays, a great demand for the development of novel drug delivery systems with high potential for bench‐to‐market transition attracts scientific attention toward materials that are already approved for biomedical use. Here, controlled fabrication of hybrid organic inorganic mesoporous crystals is realized in physiologically relevant conditions by co‐synthesis of vaterite CaCO3 in the presence of dextran (DEX) or its functional derivatives. The effects of DEX molecular weight and chemical structure on morphology, porosity, and stability of the hybrids are investigated. Molecular weight of DEX does not affect the crystal growth but leads to the partial blocking of crystal pores. Co‐synthesis of DEX functionalized with either carboxymethyl (CM) or diethylaminoethyl (DEAE) groups drastically increased crystal porosity without influencing crystal size. pH‐dependent vaterite‐to‐calcite recrystallization is significantly suppressed by inclusion of carboxymethyl‐dextran (CM‐DEX), making vaterite crystals stable in acidic medium, whereas the incorporation of diethylaminoethyl‐dextran (DEAE‐DEX) has no effect. The hybrids prepared with charged DEX derivatives possess stronger adhesion to normal human dermal fibroblasts: three times higher crystal adherence compared to pristine crystals. These results provide fundamental physical–chemical insights into the crystallization of DEX/vaterite hybrids and are discussed in view of the potential of these functional delivery carriers for biomedical and other applications.

DEAE-chitosan nanoparticles as a pneumococcus-biomimetic material for the development of antipneumococcal therapeutics

Advanced biomaterials provide an interesting and versatile platform to implement new and more effective strategies to fight bacterial infections. Chitosan is one of these biopolymers and possesses relevant features for biomedical applications. Here we synthesized nanoparticles of chitosan derivatized with diethylaminoethyl groups (ChiDENPs) to emulate the choline residues in the pneumococcal cell wall and act as ligands for choline-binding proteins (CBPs). Firstly, we assessed the ability of diethylaminoethyl (DEAE) to sequester the CBPs present in the bacterial surface, thus promoting chain formation. Secondly, the CBP-binding ability of ChiDENPs was purposed to encapsulate a bio-active molecule, the antimicrobial enzyme Cpl-711 (ChiDENPs-711), with improved stability over non-derivatized chitosan. The enzyme-loaded system released more than 90% of the active enzybiotic in ≈ 2 h, above the usual in vivo half-life of this kind of enzymes. Therefore, ChiDENPs provide a promising platform for the controlled release of CBP-enzybiotics in biological contexts.

AMPHIPATHIC CHITOSANS AS VECTORS FOR SIRNA DELIVERY

<h3>Background</h3> Polycations are promising candidates for siRNA delivery due to their ability to complex siRNA molecules into small nanoparticles (NPs)[1,2]. In this study, we have synthesized and evaluated the potential of amphipathic chitosans as siRNA carriers for the intracellular delivery of siRNA molecules. <h3>Methods</h3> Chitosans with varying degrees of acetylation (DA) and increasing proportions of diethylaminoethyl groups (DEAE) were synthesized and characterized. siRNA nanoparticles were prepared and their physicochemical properties and transfection efficiency evaluated on Raw 264.7 macrophages and HeLa-GFP cell lines. <h3>Results</h3> The results showed that the adjustment of DA and DEAE groups decreased the interparticle interactions allowing colloidal nanoparticles 150 nm in size, low polydispersity indices (0.15 - 0.2) and positive Zeta potentials (+4 mV to +12 mV) to be formed. The resistance of nanoparticles to aggregation was provided by changes in the surface of nanoparticles and their pegylation reduced the nanoparticle sizes to around 100 nm at pH 6.3. Real-time confocal microscopy measurements revealed a fast release of siRNA-FAM in the intracellular environment. In vitro transfection studies with pegylated NPs were more efficient than lipofectamine in the silencing of TNF-alpha in macrophages by 63% and 48%, respectively. Similarly, transfection studies on epithelial cells of cervical carcinoma (HeLa-GFP) also showed that derivatives modified with DEAE and PEG formed NPs that enabled an efficient GFP knockdown. <h3>Conclusion</h3> The results have provided a clear approach to overcome the limited stability of chitosan nanoparticles under physiological conditions and confer potential to these vectors for in vivo studies.

Quantitative detection of human adenovirus from river water by monolithic adsorption filtration and quantitative PCR

Water contaminated with fecally derived viruses, also known as enteric viruses, represents a particularly high risk for human health. However, they have not been included in water quality regulations yet. The detection of these viruses is often more expensive and time-consuming compared to the analysis of conventional fecal indicator organisms. In addition, most methods are not sensitive enough to detect small viral loads that may already cause serious health issues if present in water. In this study, we established a workflow for the successful and direct enrichment of human adenovirus (HAdV) from artificially contaminated river water based on monolithic adsorption filtration (MAF) and quantitative polymerase reaction (qPCR). With a clear focus on efficiency, we used targeted synthetic DNA fragments as standard for the quantification of HAdV by qPCR, leading to accurate and robust results with a qPCR efficiency of 95 %, a broad working range over 6 orders of magnitude and an LOD of 1 GU/μL. We carried out a cascade of spiking experiments, enhancing the complexity of the spiking matrix with each step to progressively evaluate MAF for the direct concentration of HAdV. We found that negatively charged MAF using monoliths with hydroxyl groups (MAF−OH) showed a better reproducibility and a significantly faster turnaround time than skimmed milk flocculation (SMF) when concentrating HAdV35 from artificially contaminated, acidified mineral water. We then validated positively charged MAF using monoliths with diethyl aminoethyl groups (MAF-DEAE) for the direct concentration of HAdV5 without pre-conditioning of water samples using tap water as spiking matrix with a less defined and controlled water chemistry. Finally, we evaluated MAF-DEAE for the direct concentration of HAdV5 from surface water using river water as representative matrix with an undefined water chemistry. We found, that MAF-DEAE achieved reproducible recoveries of HAdV5, independently of the spiked concentration level or sample volume. Furthermore, we showed, that MAF-DEAE drastically reduced the limit of detection (LOD) of HAdV5 by a factor of 115 from 6.0 ∙ 103 GU/mL before to 5.2 ∙ 101 GU/mL after MAF-DEAE. We identified that recoveries increased for smaller processing volumes with a peak at 0.5 L of 84.0 % and showed that recovery efficiency depends on sample volume and matrix type. The here presented workflow based on MAF-DEAE and qPCR offers an easy-to-implement and highly efficient alternative to existing approaches and allows for a fast detection of HAdV in water.

Protein adsorption to poly(ethylenimine)-modified Sepharose FF: VIII: Impacts of surface ion-exchange groups at different polymer grafting densities

Our previous studies on protein adsorption to the anion-exchangers of poly(ethylenimine) (PEI)-grafted Sepharose FF found that both adsorption capacity and uptake rate of bovine serum albumin (BSA) increased greatly when the PEI grafting density reached over a critical ionic capacity (cIC) due to the 3D protein binding and occurrence of “chain delivery” of bound proteins. Moreover, by the investigation on the anion-exchangers of diethylaminoethyl (DEAE)-modified and DEAE-dextran-grafted Sepharose FF, we found the unique role of surface ligand in facilitating protein uptake kinetics on dextran-functionalized anion exchangers as the “transfer station” for the “chain delivery” of bound proteins. However, what would be the contribution of surface ligands on the transport of bound proteins on PEI chains at a wide range across cIC, particularly at the lower IC range where no “chain delivery” was present? We have thus designed this research to answer the question. To this purpose, we fabricated three series of PEI-Sepharose FF resins, one without surface ligand (i.e., FF-PEI) and two with surface DEAE modifications at DEAE coupling densities of 60 and 90 mmol/L (i.e., FF-D60-PEI and FF-D90-PEI), and focused on the role of surface DEAE at different PEI densities in BSA adsorption equilibrium and uptake kinetics in a wide IC range of PEI across cIC (∼600 mmol/L for BSA). It was found that, at low grafting-ligand densities (IC<cIC), both adsorption capacity and uptake rate increased significantly (5–14% and 40–140%, respectively) after adding surface DEAE groups. At IC > cIC, however, both adsorption capacity and uptake rate changed only slightly (<5% and <10%, respectively) by the addition of surface DEAE groups. The results revealed that at IC < cIC, the surface DEAE groups provided the supplement of available binding sites and facilitated the happenings of the “chain delivery” of bound proteins as the “transfer station”, both of which were limited at the low IC range. However, at IC > cIC, the extended flexible PEI chains have already afforded 3D binding space with high accessibility and easy happening of “chain delivery” of bound proteins, so the surface DEAE groups between neighboring PEI chains did not work in assisting the transport of bound proteins. Moreover, when the IC was lower but close to the cIC, the FF-D-PEI resins exhibited higher uptake rates than FF-PEI resins at a similar or even lower IC values. These findings indicate that surface modification of charged groups in PEI-based anion exchangers of low grafting density would be an efficient strategy to fabricate high performance protein ion exchangers.

Biopolymeric Films of Amphiphilic Derivatives of Chitosan: A Physicochemical Characterization and Antifungal Study

The chemical modification of chitosan has been an active subject of research in order to improve the physicochemical and antifungal properties of chitosan-based films. The aim of this study was to evaluate the physiochemical and antifungal properties of films prepared with chitosan and its derivatives containing diethylaminoethyl (DEAE) and dodecyl groups (Dod). Chitosans and selected derivatives were synthesized and characterized, and their films blended with glycerol and sorbitol (5%, 10%, and 20%). They were studied by means of the evaluation of their mechanical, thermal, barrier, and antifungal properties. The collected data showed that molecular weight (Mw), degree of acetylation, and grafting with DEAE and Dod groups greatly affected the mechanical, thickness, color, and barrier properties, all of which could be tailored by the plasticizer percentage. The antifungal study against Aspergillus flavus, Alternaria alternata, Alternaria solani, and Penicillium expansum showed that the films containing DEAE and Dod groups exhibited higher antifungal activity than the non-modified chitosans. The mechanical properties of highly soluble films were improved by the plasticizers at percentages of 5% and 10%, indicating these derivatives as potential candidates for the coating of seeds, nuts and fruits of various crops.

Photochemical synthesis of silver nanoparticles on chitosans/montmorillonite nanocomposite films and antibacterial activity

Silver nanoparticles (AgNPs) were synthetized on chitosans/montmorillonite nanocomposite films by photochemical method. Nanocomposites were prepared using chitosans with different molar masses and deacetylation degrees, as well as modified with diethylaminoethyl (DEAE) and dodecyl groups. AgNPs formation on the films was followed by the appearance of the plasmon band around 440nm as a function of irradiation time. TEM images revealed AgNPs with spherical morphology for all nanocomposites. For nanocomposites using modified chitosans, the AgNPs synthesis occurred quickly (1.5h) while for the others films it was above 11h. The film of modified chitosan with dodecyl and DEAE groups presented smaller and more uniform nanoparticles size along mixture of exfoliated and intercalated structures. This modified chitosan is an amphiphilic compound that can act controlling the size/shape of the AgNPs. The results of antibacterial activity suggested that all nanocomposite-AgNPs films inhibited the growth of Escherichia coli and Bacillus subtilis.

Chitosan derivatives for gene transfer: effect of phosphorylcholine and diethylaminoethyl grafts on the in vitro transfection efficiency

The purpose of this work was to improve the functional properties of chitosan for gene transfer by inserting phosphorylcholine (PC) and diethylaminoethyl (DEAE) groups into the main chain. A series of derivatives containing increasing contents of DEAE and a fixed content of PC groups were synthesized and characterized, aiming to evaluate the effect of these groups on the nanoparticles’ properties and the in vitro transfection efficiency. The derivatives were soluble at physiological pH levels and all derivatives were less cytotoxic than the control, the lipid lipofectamine. The obtained derivatives complexed pDNA into nanoparticles with smaller sizes and higher zeta potentials than plain chitosan. The in vitro transfection was performed with nanoparticles prepared at pH 6.3 and 7.4 and the results showed that nanoparticles prepared with derivatives containing 20% of PC groups (PC18-CH) and high degrees of substitution by DEAE (PC20-CH-DEAE100, CH-DEAE80, CH-DEAE100) displayed the better transfection efficiencies in HeLa cells, reaching relative values comparable to lipofectamine. The most effective derivative, PC18CH, was selected for complexation with siRNA and its complexes demonstrated an in vitro knockdown efficiency highly dependent on the N/P ratio. Our combined results indicated that, by means of controlled modifications, the limitations of chitosan can be overcome to obtain more effective carriers based on chitosan, and the derivatives here studied hold potential for in vivo studies.

Textile cotton dust waste: partial diethylaminoethylation and its application to the sorption/removal of the model residual textile dye Reactive Red 239

Cellulose is the most abundant polysaccharide in nature and it encompasses a lot of industrial applications; it is from totally renewable resources and it reduces the greenhouse effect. The cotton yarn has an unavoidable loss of 8 % during any textile factory processes. Due to its intrinsic cellulosic nature, this cotton dust waste may be a convenient feedstock for chemical derivatization with diethylaminoethyl groups, thus providing a DEAE+-CDW anionic exchange matrix able to adsorb a residual dye, such as Reactive Red 239 (RR239), from textile wastewaters. A factorial design (with such parameters as alkali catalyst and derivatization reagent) and other experiments were performed to investigate the influence of the initial model dye concentration, contact time and presence of common textile salts. A selected DEAE+-CDW displayed RR239 dye sorption of 60.00 (column) and 93.41 mg g−1 (batch). A good fit was found for the Langmuir isotherm (R 2 = 0.9878) drawn from the sorption data. The use of more DEAE+ reagent in the synthesis step resulted in better DEAE+-CDW matrices, with the same being valid for the alkali concentration but with less intensity. The addition of 50 or 100 mmol L−1 NaCl increased RR239 retention by 8.15 %, and the enzymatic cellulolytic degradability of fully dyed DEAE+-CDW, compared to dye-free DEAE+-CDW, was reduced from 42.57 to 28.15 %. The data support the assumption that the DEAE+-CDW matrix is effective in the removal of the recalcitrant residual dye and or its colored degradation products still present in partially precleared textile waste sample and thus this represents an important alternative in the treatment of colored textile effluents. Shortly, a factory problem was converted in a solution for another greater environmental problem.

Synthesis, Characterization, and Antifungal Activities of Amphiphilic Derivatives of Diethylaminoethyl Chitosan against Aspergillus flavus.

Amphiphilic derivatives of diethylaminoethyl chitosan (DEAE-CH) were synthesized using a two-step process involving initial substitution with diethylaminoethyl (DEAE) groups followed by reductive amination with dodecylaldehyde. The synthesized derivatives were characterized by (1)H NMR, gel permeation, and FTIR. The associative behaviors of these compounds in aqueous solution were studied using fluorescence spectroscopy, whereas their antifungal activities against Aspergillus flavus were evaluated in terms of mycelial growth. The effects of deacetylated chitosans and their derivatives on the mycelial growth of A. flavus were evaluated at several polymer concentrations (0.05-1.0 g/L), and the results were compared. The inhibition indices of the deacetylated chitosans increased with increasing Mw (16.9 kDa < 176 kDa < 517.7 kDa); however, derivatives with a combination of either a high molecular weight (Mw) and low hydrophobicity or a low Mw and high hydrophobicity were the most effective in inhibiting the in vitro radial growth of A. flavus.

Synthesis of new penicillin derivatives as drug-like molecules for biological screening

Abstract Chemical modification of penicillin β-lactam ring was made. Six thiazolidine amides were produced through N4-C7 β-lactam ring opening of penicillin V methyl ester with various aliphatic, aromatic, and heterocyclic primary amines. Five 8-hydroxypenillic acid derivatives with side chains of methyl, propyl, benzyl, and diethylaminoethyl groups were yielded via β-lactam ring rearrangement from 6-aminopenicillanic acid (6-APA). Parallel synthetic methods were used for the alkylation of 8-hydroxypenillic acid and β-lactam ring opening of penicillin V methyl ester. The biological activities of the compounds were evaluated.

Synthesis, characterization, and drug‐release behavior of amphiphilic quaternary ammonium chitosan derivatives

ABSTRACTA new type of amphiphilic quaternary ammonium chitosan derivative, 2‐N‐carboxymethyl‐6‐O‐diethylaminoethyl chitosan (DEAE–CMC), was synthesized through a two‐step Schiff base reaction process and applied to drug delivery. In the first step, benzaldehyde was used as a protective agent for the incorporation of diethylaminoethyl groups to form the intermediate (6‐O‐diethylaminoethyl chitosan). On the other hand, NaBH4 was used as a reducing agent to reduce the Schiff base, which was generated by glyoxylic acid, for the further incorporation of carboxymethyl groups to produce DEAE–CMC. The structure, thermal properties, surface morphology, and diameter distribution of the resulting chitosan graft copolymers were characterized by Fourier transform infrared spectroscopy, 1H‐NMR, thermogravimetric analysis, differential scanning calorimetry, X‐ray powder diffraction, scanning electron microscopy, and laser particle size analysis. Benefiting from the amphiphilic structure, DEAE–CMC was able to be formed into microspheres in aqueous solution with an average diameter of 4.52 ± 1.21 μm. An in vitro evaluation of these microspheres demonstrated their efficient controlled release behavior of a drug. The accumulated release ratio of vitamin B12 loaded DEAE–CMC microspheres were up to 93%, and the duration was up to 15 h. The grafted polymers of DEAE–CMC were found to be blood‐compatible, and no cytotoxic effect was shown in human SiHa cells in an MTT [3‐(4, 5‐dimethyl‐thiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] cytotoxicity assay. These results indicate that the DEAE–CMC microspheres could be used as safe, promising drug‐delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39890.

Synthesis, characterization, and drug delivery property of 2-N-carboxymethyl-6-O-diethylaminoethyl-chitosan

Abstract A novel route is demonstrated for the synthesis of 2-N-carboxymethyl-6- O-diethylaminoethyl-chitosan (DEAE-CMC) by incorporation of carboxymethyl groups as hydrophilic moieties to the C2-NH2, and diethylaminoethyl groups as hydrophobic moieties to the C6-CH2OH of the structural unit of chitosan, via a protection-graft-deprotection procedure with benzaldehyde as protective agent. The structure, morphology, and thermal properties of the chitosan graft copolymers were characterized by means of FT-IR, 1H NMR, SEM, TGA and DSC. Chitosan and its derivatives were used as carrier of model drug-Vitamin B12 (VB12), and their controlled delivery behaviour in phosphate buffer solution (pH 7.4) were studied. The results show that the release rate of VB12 from the carrier of DEAE-CMC copolymer becomes much slower than that of chitosan in phosphate buffer solution.

Single step plasmid DNA purification using methacrylate monolith bearing combination of ion-exchange and hydrophobic groups

Purification of high quantities of human grade plasmid DNA is one of the most intensive production steps. Because of that several methods have been proposed, among them also chromatographic purification using methacrylate monoliths. Recently, a process comprising the combination of hydrophobic interaction (HIC) monolith and ion-exchange monolith was developed. In this work both chemistries were tried to be introduced on a single monolith. Methacrylate monoliths bearing octylamine groups, combination of butyl (C4) grafted methacrylate groups and diethylaminoethyl (DEAE) groups as well as grafted chains bearing both C4 and DEAE groups were prepared. All monoliths were investigated for their ionic and protein capacity and compared to conventional epoxy, C4, and DEAE methacrylate monoliths. Octylamine monolith and monolith bearing combination of C4 grafted methacrylate groups and DEAE groups were found to be the most promising candidates and were further tested for plasmid DNA (pDNA) dynamic binding capacity under ion-exchange (IEX) and HIC binding conditions and ability to separate open circular (OC) from supercoiled (SC) pDNA forms and RNA from pDNA. Since monolith bearing combination of grafted C4 methacrylate groups and DEAE groups was superior in all three tested features, exhibiting pDNA dynamic binding capacity of 4.7mg/ml under IEX conditions and 2.1mg/ml under HIC conditions, it was used for the development of a single step purification method and tested with pure pDNA as well as with cell lysate. Developed method removed over 99% of RNA, host cell proteins (HCP) and genomic DNA (gDNA) demonstrating capacity to purify around 1.5mg ofpDNA/ml of monolith from cell lysate.

Experimental Approaches to Adsorption-Desorption Dynamism of Human Serum Albumin (HSA) onto Crosslinked N,N′-Diethylaminoethyl (DEAE) Dextran Microbeads

Crosslinked N,N′-Diethylaminoethyl (DEAE) groups containing dextran microbeads have been used in human serum albumin (HSA) adsorption-desorption studies. For the HSA adsorption onto positively charged hydrophilic DEAE dextran microbeads, the adsorption kinetic was slightly decreased by the changing concentration of the protein solution. Adsorption kinetics and equilibrium isotherms for the adsorption of HSA on crosslinked DEAE dextran have been determined experimentally. Modeling of the adsorption processes on DEAE dextran microbeads were realized by applying different adsorption isotherms. Among the several isotherm equations, Langmuir and Freundlich adsorption isotherms were investigated depending on the two temperatures. These were only slightly dependent on the initial concentration of HSA but were considerably affected by the pH of the medium. The HSA adsorption capacity factor and the adsorption equilibrium constant were obtained and mathematical modeling of adsorption, adsorption rate constants and maximum adsorption were determined. Besides the adsorption mechanism, optimum ionic strength and optimum pH also were investigated. Desorption studies and desorption ratio of the system were determined for optimum medium conditions. It was been proved both experimentally and theoretically that human HSA is adsorbed by electrostatic attraction, ion-exchange, hydrophobic interaction and/or hydrogen bonding.

Acetylcholinesterase inhibitory activity of novel chitooligosaccharide derivatives

In this study, three kinds of chitooligosaccharides (COS) with different substitution groups, including aminoethyl (AE), dimethylaminoethyl (DMEM) and diethylaminoethyl (DEAE) groups, were evaluated for their inhibitory activities against cholinesterase (acetylcholinesterase and butyrylcholinesterase). These COS derivatives were synthesized and their structures were characterized as AE-COS, DMAE-COS and DEAE-COS, respectively; the structures were elucidated via spectroscopic techniques ( 1H NMR). Of these, DMAE- and DEAE-COS were synthesized for the first time in this work. These COS derivatives evidenced potent acetylcholinesterase (AChE) inhibitory activities with IC 50 values of 56.5 ± 0.26, 24.1 ± 0.39 and 9.2 ± 0.33 μg/ml, respectively; however, these compounds exhibited no activity against butyrylcholinesterase. These were further analyzed for their inhibitory pattern on AChE via Lineweaver–Burk plots. AE-COS showed non-competition type inhibition, and DMAE-COS and DEAE-COS exhibited competition type inhibition against AChE. In this study, we suggested that COS derivatives have potential as AChE inhibitors for preventing Alzheimer’s disease.

Cationic Copolymer-Mediated DNA Immobilization: Interfacial Structure and Composition As Determined by Ellipsometry, Dual Polarization Interferometry, and Neutron Reflection

DNA immobilization onto support surfaces is required in biotechnological applications such as microarrays and gene delivery. This important interfacial molecular process can be mediated from a preadsobred cationic polymer. There is, however, a lack of understanding over the control of the interfacial composition and structural distribution of the DNA immobilized. We have used a combined approach of spectroscopic ellipsometry (SE), dual polarization interferometry (DPI) and neutron reflection (NR) to determine the interfacial polymer adsorption and the subsequent DNA binding. Cationic diblock copolymers incorporating 30 phosphorylcholine (PC) groups and different diethylaminoethyl groups, referred to as MPC30-DEAn, were chosen because of their well-defined molecular architecture. While our studies revealed different effects of surface charge and hydrophobicity, the amount of copolymers adsorbed on both model surfaces showed a broad trend of increase with solution pH, indicating a strong effect arising from pH-dependent charge density on the copolymers. In contrast, the copolymer structure and solution concentration showed a weak effect under the conditions studied. The subsequent DNA binding at pH 7 showed that on both surfaces the amount of DNA immobilized followed an approximate 1:1 charge interaction for all different DNA samples studied, irrespective of single or double strand, or different DNA size, indicating the dominant effect of electrostatic interaction between the two species. Both DPI and NR revealed consistent thickness increase upon DNA binding. Furthermore, with increasing DNA size, the interfacial layer became much thicker, and charge interaction drove more extensive interfacial mixing between the two species. Our results show that the amount of DNA immobilized is controlled by the amount of cationic copolymer preadsorbed that is in turn controlled by the solution pH and surface chemistry but that is barely affected by the type and concentration of DNA or cationic copolymer.

Surface modification of non‐woven poly (ethylene terephthalate) fibrous scaffold for improving cell attachment in animal cell culture

AbstractBACKGROUND: The development of carriers with biocompatible surfaces are required to meet the needs in animal cell culture. In this work, poly (ethylene terephthalate) (PET) fibrous scaffold surfaces were chemically modified to introduce diethylaminoethyl (DEAE) groups. A packed‐bed bioreactor with DEAE‐conjugated PET fibrous scaffolds was investigated for continuous production of HBsAg by r‐CHO cells.RESULTS: The changes of surface properties were characterized by surface hydrophilicity, Attenuated total reflectance (ATR) analysis, element measurement, and scanning electron microscopy. The results showed that this treatment could improve surface hydrophilicity and roughness. Using an r‐CHO cell line as model cells, the feasibility of the DEAE‐conjugated PET fibrous scaffold in animal cell culture was evaluated by means of cell attachment efficiency measurement, MTT (3‐(4,5)‐dimethylthiathiazo(‐z‐yl)‐3,5‐di‐phenytetrazoliumromide) assay, and scanning electron microscopy observation. Enhancement of cell attachment and proliferation was exhibited in the cell culture on DEAE‐conjugated PET fibrous scaffolds. r‐CHO cells were cultured for continuous HBsAg production in a packed‐bed bioreactor with DEAE‐conjugated PET fibrous scaffolds. A cell density of 1.2 × 107 cells mL−1 working volume, cell viability of 92.8% and maximum HBsAg concentration of 3.1 mg L−1 were achieved.CONCLUSION: The packed‐bed bioreactor system with DEAE‐conjugated PET fibrous scaffolds has the potential for industrial animal cell culture application. Copyright © 2008 Society of Chemical Industry