Properties of aqueous solutions of hydrophobically modified polyethylene imines in the absence and presence of sodium dodecylsulfate

Balancing gene transfection and cytotoxicity of nucleic acid carriers with focus on ocular and hepatic disorders: evaluation of hydrophobic and hydrophilic polyethyleneimine derivatives

Polyethyleneimine (PEI) derivatives substituted by lactose, succinic acid or alkyl domains were evaluated as nonviral gene delivery vectors towards balancing gene transfection and cytotoxicity. The investigations were focused on pDNA transfection into arising retinal pigment epithelia (ARPE-19) and human hepatocellular carcinoma (HepG2) cell lines. The first mentioned cell line was chosen as motivated by the non-negligible number of ocular disorders linked to gene aberrations, whereas the second one is a cell line overexpressing the asialoglycoprotein receptor (ASGP-R), which can bind to galactose residues. The presence of short alkyl domains (C₄ and C₆), and particularly the succinylation of the PEI chains, improved the biological outputs of the gene vectors. The presence of hydrophobic units possibly enhances lytic activity, whereas the incorporation of succinic acid slightly reduces polymer-DNA interaction strength, thereby enabling more efficient intracellular unpacking and cargo release. Succinylation is also supposed to decrease cytotoxicity and avoid protein adsorption to the polyplexes. The presence of long carbon chains (for instance, C₁₂) nevertheless, results in higher levels of cytotoxicity and respective lower transfection rates. The sugar-decorated polyplexes are overall less cytotoxic, but the presence of lactose moieties also leads to larger polyplexes and notably weak polymer-DNA binding, which compromise the transfection efficiency. Yet, along with the presence of short lytic alkyl domains, the double-substitution of PEI synergistically boosts gene transfection probably due to the uptake of higher DNA and polymer amounts without cell damage. Overall, the experimental data suggest that ocular and hepatic gene therapies may be potentialized by fine-tuning the hydrophobic-to-hydrophilic balance, and succinic acid is a favorable motif for the modification of PEI.

Hybrid films composed of ethyl(hydroxyethyl)cellulose and silica xerogel functionalized with a fluorogenic chemosensor for the detection of mercury in water

Ethyl(hydroxyethyl)cellulose (EHEC) and a silica-based xerogel (SBX) were functionalized with a (18-crown-6)-styrylpyridine precursor (1) to obtain the modified polymers EHEC-1 and SBX-1, respectively. Films were obtained and the resulting materials were used as fluorogenic devices for the detection of Hg²⁺ in water. The films produced from EHEC-1 showed high water retention, making it difficult to apply as a reusable optical chemosensor. Since SBXs are recognized in the literature for their hydrophobicity, a hybrid film composed of EHEC and SBX-1 which did not show water retention was produced and characterized. This system showed rapid response time, outstanding selectivity compared to several other studied metal ions, and sensitivity for the detection of Hg²⁺ in water. The detection limit for this material using fluorescence technique was 2 ppb (∼10^-8 mol L^-1). The reversibility of the complex formed between EHEC-SBX-1 film and Hg²⁺ was demonstrated by the addition of cysteine to the medium. The result obtained also allowed the assembly of INHIBIT and IMPLICATION molecular logic gates, using Hg²⁺ and cysteine as inputs. The results described in this article have important significance in the development of novel reversible fluorogenic chemosensors and adsorbent materials for the effective removal of Hg²⁺ ions.

Polyelectrolytes Enabled Reduced Graphite Oxide Water Dispersions: Effects of the Structure, Molecular Weight, and Charge Density

The polyelectrolyte (PE)-based water dispersion of graphene-related materials (GRMs) represents an interesting intermediate for the development of advanced materials by sustainable processes. Although the proof of concept has been demonstrated, there is a lack of knowledge for what concerns the effects of parameters typical of PEs such as functionalization, molecular weight, and charge density. In this work, we evaluate the effects of such parameters on the quality and long-term stability of reduced graphite oxide (rGO) dispersion in aqueous media prepared by ultrasound sonication in the presence of different PEs. Four PEs were evaluated: polyacrylic acid (PAA), branched poly(ethylenimine) (BPEI), sodium carboxymethyl cellulose (CMC), and poly(sodium 4-styrenesulfonic acid) (PSS). The prepared dispersions were thoroughly characterized by means of UV-visible spectroscopy, thermogravimetric analysis, dynamic light scattering, and Raman spectroscopy. The highest concentrations of rGO were achieved by BPEI with a molecular weight of 25,000 and 270,000 Da (33 and 26 µg/mL, respectively). For other PEs, the rGO concentration was found to be independent of the molecular weight. The PAA-based dispersions displayed the best through-time stability while yielding homogeneous dispersion with a smaller average size and narrower size distribution.

Ready-to-use room temperature one-pot synthesis of surface-decorated gold nanoparticles with targeting attributes

Gold nanoparticles (AuNPs) can be used in diagnostic and therapeutic applications. The development of facile and fast synthetic approaches is accordingly desirable towards ready-to-use biomedical materials. We report a practical one-pot method for the synthesis in aqueous media and room temperature of surface-decorated AuNPs with enhanced biological responses. The gold ions could be reduced using only polyethyleneimine (PEI) derivatives containing sugar and-or alkyl chains acting simultaneously as reducing and stabilizing agent, without the aid of any other mediator. The process is possibly potentialized by the presence of the amino groups in the polymer chains which further confer colloidal stability. The kinetics of AuNPs nucleation and growth depends on the chemical nature of the polymer chains. Particularly, the presence of lactose moieties conjugated to the PEI chains conducted to surface-decorated AuNPs with low cytotoxicity that are remarkably faster uptaken by HepG2 cells. These cells overexpress asialoglycoprotein (ASGP-R), a galactose receptor. These findings may kick off significant advances towards the practical and ready-to-use manufacturing of functionalized AuNPs towards cell-targeting since the methodology is applicable for a large variety of other ligands that can be conjugated to the same polymer chains.

A novel water-stable two-dimensional zeolitic imidazolate frameworks thin-film composite membrane for enhancements in water permeability and nanofiltration performance

Polymer membranes for water treatment are constrained by the permeability-separation trade-off. Herein, two-dimensional (2D) zeolitic imidazolate frameworks (ZIFs) made of benzimidazole interconnected with Zn ions are used to create 2D Zn₂(Bim)₄ molecular sieve nanosheets, which is explored as an asymmetric, thin-film composite (TFC) nanofiltration (NF) membrane for removing organic dyes and salts from water with a high water permeability under a low operating pressure (1 bar). The 2D Zn₂(Bim)₄ TFC NF membrane is synthesized via ionic bonds between polycations and the peripheral hydroxy groups of 2D Zn₂(Bim)₄ nanosheets, regulating the assembly of 2D Zn₂(Bim)₄ to create a novel crack-free functional layer on top of a polyvinylidene fluoride (PVDF) ultrafiltration membrane. FESEM and XPS confirmed the presence of a polycations-regulated ultrathin functional layer with a thickness of ∼37 nm on the PVDF support. Benefiting from its structural feature, our 2D Zn₂(Bim)₄ TFC NF membrane could achieve an ultra-high flux of ∼290 L/(m²·h·bar) (5-10-fold higher than that of graphene-based membranes), good anti-fouling properties and high rejection rates (above 98%) for organic dyes. Moreover, the desalinization rate is 50-75%. That is, our membrane is endowed with NF capability, and its intrinsic ultrafiltration features (high water permeance, ultrafast, and energy-saving) are also well maintained.

The supramolecular polymer complexes with oppositely charged calixresorcinarene: hydrophobic domain formation and synergistic binding modes

The association of branched polyethyleneimine (PEI) with a series of octacarboxy-calixresorcinarenes bearing different low-rim substituents leads to the formation of nanosized supramolecular complexes. The PEI-macrocycle complexes have fine-tunable sizes regulated by variations in the self-association capacity of the calixresorcinarenes. In the supramolecular complexes, hydrophobic fragments of the polymer and calixresorcinarenes form cooperative hydrophobic domains which provide synergistic enhancement of guest molecule binding. The formation of the supramolecular complexes was investigated by NMR FT-PGSE, NMR 2D NOESY, DLS and TEM methods. In addition, fluorimetry and UV-vis methods were used with the help of optical probes, namely water-soluble Crystal Violet and water-insoluble Orange OT. The investigation demonstrates the first example of the formation of cooperative hydrophobic domains in supramolecular polyelectrolyte-macrocycle complexes which enhance the binding of both water-soluble and water-insoluble organic compounds. The presented supramolecular systems have potential as sensory and drug delivery systems.

Polycationic Polymer-Regulated Assembling of 2D MOF Nanosheets for High-Performance Nanofiltration

Herein, a two-dimensional metal-organic framework (2D MOF) made of iron porphyrin complex (TCP(Fe)) interconnected with divalent metal ion (M = Zn, Co, and Cu) is used to construct a selective layer, which is explored as an ultrafast and energy-saving nanofiltration (NF) membrane for removing organic dyes from water. Among the layered 2D M-TCP(Fe) membranes, Zn-TCP(Fe) membranes display the highest water permeance, which is 3 times higher than graphene-based membranes with similar rejection. To further improve the separation performances, we utilize polycations to anchor the periphery carboxylic groups of nanosheets, regulating the assembly of 2D Zn-TCP(Fe) nanosheets to produce a new class of crack-free selective layer possessing ultrathin and highly ordered nanochannels for efficient NF. Benefiting from these structural features, our polycation-regulated 2D Zn-TCP(Fe) membranes could offer ultrahigh permeance of 4243 L m^-2 h^-1 bar^-1 (2-fold higher than its pristine) and excellent rejection rates (over 90%) for organic dye with size larger than 0.8 × 1.1 nm. This permeance value is about 2 orders of magnitude higher than the commercial polymeric NF membrane. Additionally, the membranes demonstrate 20-40% salt rejection.

Properties of polyplexes formed through interaction between hydrophobically-modified poly(ethylene imine)s and calf thymus DNA in aqueous solution

Polycationic polymers and DNA form soluble complexes in aqueous solution, which allows the transfer of genetic material into cells. Therefore, these chemically-modified polymers are of interest for use in studies aimed at better transfection efficiency and gene expression along with reduced cytotoxicity. In this study, branched poly(ethylene imine) (PEI) was modified by alkylation with n-alkyl groups (n = 4, 6, 8 and 12 carbons). The polyplexes formed through interaction of the modified PEIs and calf thymus DNA (ctDNA) were investigated using UV-Vis spectrophotometry, ethidium bromide fluorescence emission, circular dichroism spectroscopy, dynamic light scattering, and small-angle X-ray scattering techniques along with the determination of the zeta potential and viscosity. According to the results obtained, the formation of ctDNA-PEI polyplexes occurs in three steps. Firstly, when a small amount of polyelectrolyte is present the ctDNA chains are partially compacted. Subsequently, with the addition of more polyelectrolyte, the complexes have a null charge density and micrometric size. Lastly, with a higher concentration of PEI, the ctDNA is fully compacted by the PEI chains, leading to positively charged complexes with R_h values in the range of 52.0-86.0 nm. The viscosity and SAXS analysis suggested that the unmodified PEI exhibits the strongest interaction and promotes the best ctDNA condensation.

Synthesis and characterization of bioreducible heparin-polyethyleneimine nanogels: application as imaging-guided photosensitizer delivery vehicle in photodynamic therapy

HPC nanogels possess bright blue fluorescence which eliminates the use of additional probing agents in image-guided drug delivery. The results showed that disulfide crosslinked HPC nanogels are promising vehicles for stimulated photosensitizer delivery in advanced PDT.

Antibiofilm and Antimicrobial Activity of Polyethylenimine: An Interesting Compound for Endodontic Treatment

AIM

Bacteria levels of necrotic teeth are greatly reduced after endodontic treatment procedures but the presence of persisting microorganisms leads to continuous efforts to develop materials with antimicrobial properties. The purpose of the study was to determine the antimicrobial activity of polyethylenimine (PEI) against common bacteria and yeasts, regarding planktonic cells and biofilm, and to clarify its antimicrobial mechanism of action through flow cytometry.

MATERIALS AND METHODS

The antibiofilm and antimicrobial effect of PEI was determined against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Candida albicans strains using reference protocols. The effect of PEI was evaluated regarding adhesion, biofilm formation and biofilm disaggregation. In order to understand PEI cellular effects flow cytometric analysis was performed with different fluorescent markers.

RESULTS

It was verified that minimal inhibitory concentrations (MIC) values and minimal lethal concentrations (MLC) obtained for PEI were similar and ranged between 50 and 400 mg/l, proving the microbicidal and fungicidal activity of this compound. Antibiofilm activity was also proved for all the microorganisms. Severe lesion of the membrane and cell depolarization was demonstrated.

CONCLUSION

Polyethylenimine showed antimicrobial and antibiofilm activity against microorganisms often associated with apical periodontitis.

CLINICAL SIGNIFICANCE

Theoretically, prolonging the antibacterial effects of materials used in endodontics may be interesting to help prevent reinfection and possibly to affect residual bacteria that survived the treatment procedures.

Self-assembled structures of anionic hydrophobically modified polyacrylamide with star-shaped trimeric and hexameric quaternary ammonium surfactants

The self-assembly of a 1% hydrophobically modified and 30% hydrolyzed polyacrylamide (C12PAM) with cationic star-shaped oligomeric surfactants has been investigated by isothermal titration microcalorimetry, turbidimetry, ζ potential, scanning electron microscopy, and (1)H NMR techniques. The oligomeric surfactants are composed of quaternary dodecyldimethylammonium ions with three or six hydrophobic chains connected by a polyamine spacer at the headgroup level, abbreviated as DTAD and PAHB, respectively. DTAD/C12PAM and PAHB/C12PAM mixed systems undergo the same aggregate transitions with increases in surfactant concentration from soluble networklike aggregates to precipitated denser and more cross-linked structures and then to soluble spherical aggregates. The networklike aggregates are generated at very low surfactant concentration. However, at the corresponding surfactant concentration without C12PAM, DTAD cannot form aggregates and PAHB forms only networklike aggregates with a very loose structure. The strong electrostatic and hydrophobic interaction of DTAD and PAHB with C12PAM and the hydrophobic interaction between the alkyl chains of DTAD and PAHB themselves evidently promote the formation of networklike aggregates. As the surfactant concentration increases, cationic surfactants become excessive. The molecular configuration is changed by the stronger hydrophobic association among the DTAD and PAHB molecules and the enhanced electrostatic repulsion between the mixed aggregates. Thus, the networklike aggregates transfer to spherical aggregates.

Chiral cationic polyamines for chiral microcapsules and siRNA delivery

Reported herein is the use of chiral cationic polyamines for two intriguing applications: fabrication of chiral covalently-linked microcapsules, and enantiospecific delivery of siRNA to Huh 7 cells. The microcapsules are easily fabricated from homochiral polymers, and the resulting architectures can be used for supramolecular chiral catalysis and many other potential applications. Enantiospecific delivery of siRNA to Huh 7 cells is seen by one 'enantiomer' of the polymers delivering siRNA with significantly improved transfection efficiency and reduced toxicity compared to the 'enantiomeric' polymer and commercially available transfection reagents. Taken together, the use of these easily accessible polyamine structures for diverse applications is highlighted in this Letter herein and can lead to numerous future research efforts.

Properties of aqueous solutions of lentinan in the absence and presence of zwitterionic surfactants

Morphological and conformational transitions of lentinan (LT), a β-glucan extracted from Shiitake mushrooms (Lentinula edodes), were investigated at different concentrations of aqueous NaOH, using Small Angle X-ray Scattering (SAXS) technique. At low NaOH(aq) concentration LT chains are self-associated and adopt the triple helix form where as at higher NaOH concentrations the polymer chains undergo a transition to random coil chains. Also, the presence of fractal dimensions was observed through analysis of the exponential decay of the scattering intensity as a function of the scattering angle. In addition, the lateral radius of gyration was determined for LT in different concentrations of NaOH solution, indicating a rigid triple helix present as a small rod-like structure. Interactions of LT with two zwitterionic surfactants were investigated by surface tension, fluorescence, and static light scattering measurements. Experimental data showed that the formation of LT-(surfactant) complexes occurred through a cooperative process.