Hybrid Silica Xerogel and Titania/Silica Xerogel Dispersions Reinforcing Hydrophilicity and Antimicrobial Resistance of Leathers

Four leather substrates from different animals were treated by dispersions containing hydrophilic composite silica-hyperbranched poly(ethylene imine) xerogels. Antimicrobial activity was introduced by incorporating silver nanoparticles and/or benzalkonium chloride. The gel precursor solutions were also infused before gelation to titanium oxide powders typically employed for induction of self-cleaning properties. The dispersions from these biomimetically premade xerogels integrate environmentally friendly materials with short coating times. Scanning electron microscopy (SEM) provided information on the powder distribution onto the leathers. Substrate and coating composition were estimated by infrared spectroscopy (IR) and energy-dispersive X-ray spectroscopy (EDS). Surface hydrophilicity and water permeability were assessed by water-contact angle experiments. The diffusion of the leather's initial components and xerogel additives into the water were measured by Ultraviolet-Visible (UV-Vis) spectroscopy. Protection against GRAM- bacteria was tested for Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae against GRAM+ bacteria for Staphylococcus aureus and Enterococcus faecalis and against fungi for Candida albicans. Antibiofilm capacity experiments were performed against Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecalis, and Candida albicans. The application of xerogel dispersions proved an adequate and economically feasible alternative to the direct gel formation into the substrate's pores for the preparation of leathers intended for medical uses.

Synthesis and characterization of polyethyleneimine-terminated poly(β-amino esters) conjugated with pullulan for gene delivery

Cationic polymers endowed with a flexible system for condensing DNA, are regarded as effective materials for gene delivery. The synthesis of poly(β-amino esters) (pBAEs) based on 1,4-butanediol diacrylate-ethanolamine monomer (1.2:1 molar ratio) and 1,4-butanediol diacrylate-ethylene diamine (1:2 molar ratio) were carried out and modification with 1800 Da polyethyleneimine (PEI) at different weight ratios (3 and 1) as well as conjugation with pullulan in various weight ratios of (0.0625, 0.125, 0.25, and 1) performed. Gel-retardation assay demonstrated that the synthesized polymers were able to condense DNA at low carrier/plasmid (C/P) ratios. The polyplexes with ratio 3 of PEI (pβ₁/PEI₃) were restricted in all C/P ratios and the polyplexes of pβ₁/PEI₃/pull_0.125 were condensed at C/P ratios higher than 0.5. The particle size at C/P were approximately about 200 nm with a positive surface charge. The presence of the pullulan in the structure of the synthesized pBAEs could be effective in reducing toxicity of the base polymer. Highest metabolic activity dedicated to C/P₂ of pβ₂/PEI₃/pull_0.125 with 80.6 percent viability. Furthermore, the most efficient gene reporter delivery was seen at C/P ratio of 6 in pβ₂/PEI₃/pull_0.125 nanoparticles. Therefore, pullulan grafting could enhance the cellular response of cells in terms of cytotoxicity and transfection efficiency.

Cytotoxicity and internalization analysis of silicon nanowires in Buffalo Green Monkey cells: a preliminary study to evaluate the possibility of carrying viruses inside the cells

Silicon nanowires (SiNWs) are attractive functional nanomaterials for biomedical applications. The ability to easily tune their size and density, potential biocompatibility, and knowledge of the chemical activation of SiNWs surface make them natural tools to interact with biological materials. We evaluated the possibility of exploiting SiNWs as carriers to introduce organic compounds into cells. The cellular toxicity and the internalization capacity of free-standing and label-free SiNWs were tested on Buffalo Green Monkey cells (BGM). Confocal fluorescent observation of SiNWs conjugated with fluorescein-polyethylene imine (PEI) confirmed the internalization of the NWs into the Buffalo Green Monkey Cells (BGM).

Polymer Blends for Improved CO2 Capture Membranes

We investigated the possibility of improving the performance of polysulfone (PSf) membranes to be used in carbon dioxide capture devices by blending PSf with a commercial polyethylene imine, Lupasol G20, previously modified with benzoyl chloride (mG20). Additive amount ranged between 2 and 20 wt %. Membranes based on these blends were prepared by phase inversion precipitation and exhibited different morphologies with respect to neat PSf. Surface roughness, water contact angles, and water uptake increased with mG20 content. Mass transfer coefficient was also increased for both N₂ and CO₂; however, this effect was more evident for carbon dioxide. Carbon dioxide absorption performance of composite membranes was evaluated for potassium hydroxide solution in a flat sheet membrane contactor (FSMC) in cross flow module at different liquid flow rates. We found that, at the lowest flow rate, membranes exhibit a very similar behaviour to neat PSf; nevertheless, significant differences can be found at higher flow rates. In particular, the membranes with 2 and 5 wt % additive behave more efficiently than neat PSf. In contrast, 10 and 20 wt % additive content has an adverse effect on CO₂ capture when compared with neat PSf. In the former case, a combination of additive chemical affinity to CO₂ and membrane porosity can be claimed; in the latter case, the remarkably higher wettability and water uptake could determine membrane clogging and consequent loss of efficiency in the capture device.

Zeta Potential Changing Polyphosphate Nanoparticles: A Promising Approach To Overcome the Mucus and Epithelial Barrier

The aim of the present study was to develop zeta potential-changing polyphosphate nanoparticles (pp-NPs) in order to overcome the diffusion barrier of the mucus gel layer and to provide an enhanced cellular uptake. pp-NPs were obtained by in situ gelation between cationic polyethylene imine and anionic polyphosphate. The resulting pp-NPs were characterized with regard to size and zeta potential. Phosphate release studies were carried out by incubation of pp-NPs with isolated as well as cell-associated intestinal alkaline phosphatase (IAP) and quantified by malachite green assay. Correspondingly, change in the zeta potential was measured, and pp-NPs were analyzed by scanning electron microscopy studies. Mucus permeation studies were performed with porcine intestinal mucus via the transwell insert method and rotating tube method. Furthermore, cell viability and cellular uptake were investigated on Caco-2 cells. The resulting pp-NPs displayed a mean size of 269.16 ± 1.12 nm and a zeta potential between -9 and -10 mV in the characterization studies. Within 4 h, a remarkable amount of phosphate was released from pp-NPs incubated with isolated IAP as well as cell-associated IAP and zeta potential raised up from -9.14 ± 0.45 to -1.75 ± 0.46 mV. Compared with dephosphorylated polyphosphate nanoparticles (de-pp-NPs), a significantly enhanced mucus permeation of pp-NPs was observed. Moreover, pp-NPs did not exhibit cytotoxicity. Cellular uptake increased 2.6-fold by conversion of pp-NPs to de-pp-NPs following enzymatic cleavage. Taking the comparatively simple preparation method and the high mucus-permeating properties of pp-NPs and high cellular uptake properties of de-pp-NPs into account, these nanocarriers might be promising novel tools for mucosal drug delivery.

Glial cell line-derived neurotrophic factor gene delivery via a polyethylene imine grafted chitosan carrier

Parkinson’s disease is known to result from the loss of dopaminergic neurons. Direct intracerebral injections of high doses of recombinant glial cell line-derived neurotrophic factor (GDNF) have been shown to protect adult nigral dopaminergic neurons. Because GDNF does not cross the blood–brain barrier, intracerebral gene transfer is an ideal option. Chitosan (CHI) is a naturally derived material that has been used for gene transfer. However, the low water solubility often leads to decreased transfection efficiency. Grafting of highly water-soluble polyethylene imines (PEI) and polyethylene glycol onto polymers can increase their solubility. The purpose of this study was to design a non-viral gene carrier with improved water solubility as well as enhanced transfection efficiency for treating Parkinsonism. Two molecular weights (Mw =600 and 1,800 g/mol) of PEI were grafted onto CHI (PEI600-g-CHI and PEI1800-g-CHI, respectively) by opening the epoxide ring of ethylene glycol diglycidyl ether (EX-810). This modification resulted in a non-viral gene carrier with less cytotoxicity. The transfection efficiency of PEI600-g-CHI/deoxyribonucleic acid (DNA) polyplexes was significantly higher than either PEI1800-g-CHI/DNA or CHI/DNA polyplexes. The maximal GDNF expression of PEI600-g-CHI/DNA was at the polymer:DNA weight ratio of 10:1, which was 1.7-fold higher than the maximal GDNF expression of PEI1800-g-CHI/DNA. The low toxicity and high transfection efficiency of PEI600-g-CHI make it ideal for application to GDNF gene therapy, which has potential for the treatment of Parkinson’s disease.

Cholera toxin breakdowns oral tolerance via activation of canonical NF-κB

The mechanisms of mucosal immunogenicity and adjuvanticity of bacterial exotoxins remains unknown. In this study, we investigated the role of the transcription factor nuclear factor-κB (NF-κB) in cholera toxin (CT)-induced alteration of oral tolerance. Feeding CT abrogated ovalbumin (OVA)-induced oral tolerance, as evaluated by OVA-specific serum antibody responses, and CD4(+) T cell proliferation. CT feeding activated canonical NF-κB (one heterodimer type, p50-p65) and mRNA expression of NF-κB-dependent proinflammatory cytokines in mesenteric lymph node (MLN) and Peyer's patch (PP) cells. CT no longer showed abrogation of oral tolerance in mice pretreated with p50 small interfering RNAs (siRNAs). ADP-ribosylation inhibitors inhibited CT-induced NF-κB activation. These data suggest that CT induces canonical NF-κB activation in intestinal lymphoid cells, which plays a key role in mucosal immunogenicity and adjuvanticity.

Targeting autophagy as a potential therapeutic approach for melanoma therapy. Semin Cancer Biol. 2013;23:352-360. [PMID: 23831275 DOI: 10.1016/j.semcancer.2013.06.008]

Melanoma, occurring as a rapidly progressive skin cancer, is resistant to current chemo- and radiotherapy, especially after metastases to distant organs has taken place. Most chemotherapeutic drugs exert their cytotoxic effect by inducing apoptosis, which, however, is often deficient in cancer cells. Thus, it is appropriate to attempt the targeting of alternative pathways, which regulate cellular viability. Recent studies of autophagy, a well-conserved cellular catabolic process, promise to improve the therapeutic outcome in melanoma patients. Although a dual role for autophagy in cancer therapy has been reported, both protecting against and promoting cell death, the potential for using autophagy in cancer therapy seems to be promising. Here, we review the recent literature on the role of autophagy in melanoma with respect to the expression of autophagic markers, the involvement of autophagy in chemo- and immunotherapy, as well as the role of autophagy in hypoxia and altered metabolic pathways employed for melanoma therapy.

Electron Spin Resonance Spectra of Polymer Radicals in Aqueous Solution

Mixing of aqueous polymer solutions containing Ti3+ and H2O2 in a rapid flow mixer produced radicals by abstraction, OH + RH → R · + H2O, which were observed by electron spin resonance. Oscillation of segments was sufficient to narrow the lines to 0.5-2.0 g. Polymers and radicals identified with more or less certainty were polyacrylic acid, 〰CH(CO2H)ĊHCH(CO2H)〰, polymethacrylic acid, 〰C(CH3)(CO2H)ĊHC(CH3)(CO2H)〰, polyvinyl alcohol, 〰CHOHĊHCHOH〰, and one indefinite, polyethylene imine, 〰CH2ṄCH2〰 or 〰CH2ṄOCH2〰, polyethylene oxide, 〰CH2OĊHCH2O〰. Radicals from polypropylene oxide, dextran, dextrin, soluble starch, and the disaccharide maltose were unidentified; the last three were strikingly similar. Products of secondary C-C scission were not observed with certainty. It is presumed that such reactions are slow compared to the time-scale of the experiment, 10 msec. However, some evidence exists for a very rapid β-OH loss in carbohydrate radicals and a slow C-O scission in polyethylene oxide radicals. A large number of related small molecule radicals were investigated, and hyperfine splittings and g-values are reported.