Developmental Potency and Metabolic Traits of Extended Pluripotency Are Faithfully Transferred to Somatic Cells via Cell Fusion-Induced Reprogramming.

As a novel cell type from eight-cell-stage embryos, extended pluripotent stem cells (EPSCs) are known for diverse differentiation potency in both extraembryonic and embryonic lineages, suggesting new possibilities as a developmental research model. Although various features of EPSCs have been defined, their ability to directly transfer extended pluripotency to differentiated somatic cells by cell fusion remains to be elucidated. Here, we derived EPSCs from eight-cell mouse embryos and confirmed their extended pluripotency at the molecular level and extraembryonic differentiation ability. Then, they were fused with OG2+/- ROSA+/- neural stem cells (NSCs) by the polyethylene-glycol (PEG)-mediated method and further analyzed. The resulting fused hybrid cells exhibited pluripotential markers with upregulated EPSC-specific gene expression. Furthermore, the hybrid cells contributed to the extraembryonic and embryonic lineages in vivo and in vitro. RNA sequencing analysis confirmed that the hybrid cells showed distinct global expression patterns resembling EPSCs without parental expression of NSC markers, indicating the complete acquisition of extended pluripotency and the erasure of the somatic memory of NSCs. Furthermore, ultrastructural observation and metabolic analysis confirmed that the hybrid cells rearranged the mitochondrial morphology and bivalent metabolic profile to those of EPSCs. In conclusion, the extended pluripotency of EPSCs could be transferred to somatic cells through fusion-induced reprogramming.

Expression of a Cutinase of Moniliophthora roreri with Polyester and PET-Plastic Residues Degradation Activity.

Cutinases are enzymes produced by phytopathogenic fungi like Moniliophthora roreri. The three genome-located cutinase genes of M. roreri were amplified from cDNA of fungi growing in different induction culture media for cutinase production. The mrcut1 gene was expressed in the presence of a cacao cuticle, while the mrcut2 and mrcut3 genes were expressed when an apple cuticle was used as the inducer. The sequences of all genes were obtained and analyzed by bioinformatics tools to determine the presence of signal peptides, introns, glycosylation, and regulatory sequences. Also, the theoretical molecular weight and pI were obtained and experimentally confirmed. Finally, cutinase 1 from M. roreri (MRCUT1) was selected for heterologous expression in Escherichia coli. Successful overexpression of MRCUT1 was observed with the highest enzyme activity of 34,036 U/mg under the assay conditions at 40°C and pH 8. Furthermore, the degradation of different synthetic polyesters was evaluated; after 21 days, 59% of polyethylene succinate (PES), 43% of polycaprolactone (PCL), and 31% of polyethylene terephthalate (PET) from plastic residues were degraded. IMPORTANCE Plastic pollution is exponentially increasing; even the G20 has recognized an urgent need to implement actions to reduce it. In recent years, searching for enzymes that can degrade plastics, especially those based on polyesters such as PET, has been increasing as they can be a green alternative to the actual plastic degradation process. A promising option in recent years refers to biological tools such as enzymes involved in stages of partial and even total degradation of some plastics. In this context, the MRCUT1 enzyme can degrade polyesters contained in plastic residues in a short time. Besides, there is limited knowledge about the biochemical properties of cutinases from M. roreri. Commonly, fungal enzymes are expressed as inclusion bodies in E. coli with reduced activity. Interestingly, the successful expression of one cutinase of M. roreri in E. coli with enhanced activity is described.

Influence of liner offset and locking mechanism on fatigue durability in highly cross-linked polyethylene total hip prostheses.

Highly cross-linked, ultrahigh molecular weight polyethylene (HXLPE) acetabular liners are inherently associated to a risk of fatigue failure due to femoral neck impingement. Different thicknesses and designs employed with HXLPE liners greatly affect mechanical loading scenario. The purpose of this study was to clarify the influence of liner offset (lateralization) and locking mechanism (presence/absence of anti-rotation tabs in the external surface) on fatigue durability in annealed and vitamin E-blended HXLPE liners with a current commercial design. Each liner tested had six anti-rotation tabs, which were engaged in the 6 of 12 recesses on the metal shell. The remaining six recesses had no direct contact with the liner, where HXLPE was mechanically unsupported by the metal backing. These mated and/or unmated rim regions in the offset (2, 3, 4-mm lateralized) liners were exposed to severe neck impingement until crack propagation was identified. Phase volume percentages (crystalline, amorphous, and intermediate phase contents) of HXLPE liners were compared before and after impingement in order to interpret differences in impingement micromechanics associated with the rim design variations. Our results showed that the presence of unmated recesses served as a stress concentrator due to the formation of millimeter-scale gaps between the liner and shell. Another potential design problem drawn from our study was liner offset associated with a small volume protruding above the metal rim. Therefore, surgeons should take special care in selecting locking designs and geometries especially when using HXLPE offset liners.

A hairpin-type DNA probe for direct colorimetric detection of endonuclease activity and inhibition based on the deaggregation of gold nanoparticles.

A method is described for the determination of the activity of endonuclease. It based on the deaggregation of gold nanoparticles (AuNPs) aggregated by the action of poly(diallyldimethylammonium chloride) (PDDA). A single-stranded DNA (ssDNA) is released after enzymatic cleavage catalyzed by endonuclease. The released fragments bind electrostatically to PDDA and inhibit the PDDA-induced aggregation of AuNPs. This is accompanied by a color change from blue to red and a decrease in the absorption ratio (A630/A520). Under the optimal conditions, this ratio increases linearly in the 0.001 to 1 U·µL-1 EcoRI endonuclease activity range. The detection limit is of 2 × 10-4 U·µL-1 which is much better or at least comparable to previous reports. The method is deemed to have wide scope in that it may be used to study other endonuclease activity (such as BamHI) by simply changing the specific recognition site of the hairpin-like DNA probe. The assay may also be employed to screening for inhibitors of EcoRI endonuclease. Graphical abstract Schematic presentation of the colorimetric assay based on the deaggregation of AuNPs for the detection of endonuclease activity. A single-stranded sequence (ssDNA) is released by the EcoRI cleavage, which electrostatically binds to PDDA and inhibits the PDDA-induced aggregation of AuNPs accompanying with a color change from blue to red.

Interactions of bioactive molecules with thin dendritic glycopolymer layers.

The authors report on highly swellable, stable layers of spherical dendritic glycopolymers, composed of hyperbranched poly(ethylene imine) (PEI) as core and two different maltose shells (A = dense shell and B = open shell). These glycopolymers are cross-linked and attached with poly(ethylene-alt-maleic anhydride) (PEMA) or citric acid on SiOx substrates. The swelling and adsorption of biomolecules were analyzed by spectroscopic ellipsometry and quartz crystal microbalance with dissipation. The swelling degree and complexation with the drug molecule adenosine triphosphate (ATP) were found to be up to 10 times higher for dendritic glycopolymer layers cross-linked with PEMA than for layers cross-linked with citric acid. ATP complexation by electrostatic interaction with the PEI cores was confirmed by x-ray photoelectron spectroscopy analysis. Complexation led to partial collapsing, stiffening, and increase of polymer layer viscosity of the PEMA cross-linked layers. From modeling of ellipsometric data, it was deduced that ATP complexation preferably takes place at the polymer layer-solution interface. The size effect of the adsorbates was investigated by comparing ATP complexation with the adsorption of larger vitamin B12 and human serum albumin (HSA) protein. PEI-Mal A cross-linked with PEMA was found to be resistant toward B12 and HSA adsorption due to the diffusion barrier of the polymer layer. Thus, the authors present potentially biocompatible polymer surfaces for drug loading and their surface supported release.

Design of PEI-conjugated bio-reducible polymer for efficient gene delivery.

The poly(cystaminebis(acrylamide)-diaminohexane) (poly(CBA-DAH)) was designed previously as a bio-reducible efficient gene delivery carrier. However, the high weight ratio required to form the polyplexes between poly(CBA-DAH) with pDNA is still a problem that needs to be addressed. To solve this problem and increase the transfection efficiency, poly(ethylenimine) (PEI, 1.8 kDa) was conjugated to poly(CBA-DAH) via disulfide bond. The PEI conjugated poly(CBA-DAH) (PCDP) can bind with pDNA at a very low weight ratio of 0.5 and above, like PEI 25 kDa, and form the polyplexes with nano-size (102-128 nm) and positive surface charge (27-34 mV). PCDP and PCDP polyplexes had negligible cytotoxicity and indicated similar or better cellular uptake than the comparison groups such as PEI 25 kDa and Lipofectamine® polyplexes. To confirm the transfection efficiency, the plasmid DNA (pDNA) encoded with the luciferase reporter gene (gWiz-Luc) and green fluorescent protein reporter gene (GFP) were used and treated with PCDP into the A549, Huh-7, and Mia PaCa-2 cells. PCDP/pDNA polyplexes showed highest transfection efficiency in all tested cell lines. In the luciferase assay, PCDP polyplexes showed 10.2 times higher gene transfection efficiency than Lipofectamine® polyplexes in mimic in vivo conditions (30% FBS, A549 cells). The VEGF siRNA expressing plasmid (pshVEGF), which is constructed as a therapeutic gene by our previous work, was delivered by PCDP into the cancer cells. The VEGF gene expression of PCDP/pshVEGF polyplexes was dramatically lower than control and the VEGF gene silencing efficiencies of PCDP/pshVEGF (w/w; 10/1) polyplexes were 54% (A549 cells), 77% (Huh-7 cells), and 66% (Mia PaCa-2 cells). In addition, PCDP/pshVEGF had reduced cell viability rates of about 31% (A549 cells), 39% (Huh-7 cells), and 42% (Mia PaCa-2 cells) and showed better results than all comparison groups. In the transfection efficiency and VEGF silencing assay, PCDP polyplexes showed better results than poly(CBA-DAH) at 4-fold lower weight ratio. The data of all experiments demonstrate that the synthesized PCDP could be used for efficient gene delivery and could be widely applied.

Collapse of DNA in packaging and cellular transport.

The dawn of molecular biology and recombinant DNA technology arose from our ability to manipulate DNA, including the process of collapse of long extended DNA molecules into nanoparticles of approximately 100 nm diameter. This condensation process is important for the packaging of DNA in the cell and for transporting DNA through the cell membrane for gene therapy. Multivalent cations, such as natural polyamines (spermidine and spermine), were initially recognized for their ability to provoke DNA condensation. Current research is targeted on molecules such as linear and branched polymers, oligopeptides, polypeptides and dendrimers that promote collapse of DNA to nanometric particles for gene therapy and on the energetics of DNA packaging.

A star-shaped poly(2-methyl-2-oxazoline)-based antifouling coating: Application in investigation of the interaction between acetaminophen and bovine serum albumin by frontal analysis capillary electrophoresis.

In this work, an antifouling capillary modified with star-shaped poly(2-methyl-2-oxazoline)-based copolymer was used to study the interaction between acetaminophen (APAP) and bovine serum albumin (BSA) by frontal analysis capillary electrophoresis (FACE). The star-shaped copolymer, poly(ethylene imine)-graft-poly(2-methyl-2-oxazoline) (PEI-g-PMOXA), was immobilized onto the fused-silica capillary inner wall via dopamine-assisted co-deposition strategy, yielding a PEI-g-PMOXA/polydopamine (PDA)-coated antifouling capillary, i.e., an antifouling capillary coated with the PEI-g-PMOXA/PDA co-deposited film. Electroosmotic flow (EOF) mobility of the PEI-g-PMOXA/PDA-coated capillary was almost zero in a wide pH range (3.0-10.0), while the EOF mobility of bare capillary was much larger and increased significantly with pH increasing. When the PEI-g-PMOXA/PDA-coated capillary was exploited to separate a protein mixture including cytochrome c, lysozyme, ribonuclease A and α-chymotrypsinogen A, the theoretical plate numbers were of five orders of magnitude which were about ten-fold higher over those obtained with bare capillary; in addition, the RSD values of migration time were mostly less than 0.7% (30 consecutive runs) which were much smaller than those of bare capillary (c.a. 5.7%). The protein-resistant PEI-g-PMOXA/PDA-coated capillary was then used to investigate the interaction between APAP and BSA by FACE, the binding constant and number of binding sites at 25°C and pH 7.4 (Tris/HCl buffer of 25mM) were 1.39×104M-1 and 1.08, respectively, which were comparable to the results determined by fluorescence spectroscopic measurement (3.18×104M-1 and 1.19, respectively).

Poly (methyl vinyl ether-co-maleic acid) - Pectin based hydrogel-forming systems: Gel, film, and microneedles.

Cross-linking of natural and synthetic polymers is widely explored to achieve the desired material properties (mechanical strength, drug loading capacity, swelling and erosion rates). However, the potential of polymers produced by crosslinking poly (methyl vinyl ether-co-maleic acid) (PMVE/MA) and pectin (PE) in pharmaceutics is mainly unexplored so far. We have investigated the effect of various esterification conditions and pectin content on the physicochemical properties. Materials have been characterized by fourier transform infrared, differential scanning calorimetry and scanning electron microscopy. In addition, swelling and bioadhesive features of PMVE/MA-PE hydrogel systems were investigated. A band shift for the carbonyl group from 1706 to 1776cm-1, and glass transition (Tg) increased from 55.4±0.9°C to 119.5±0.3°C confirmed the formation of esterification reaction within the cross-linked films. Cross-linked PMVE/MA:PE films with a ratio of 5 demonstrated a superior mass increase when compared to 2.5, 3.125, 3.75, 6.25, and 7.5 ratios of the same hydrogel film. Formulations containing PMVE/MA and pectin with a ratio of 3.75 showed superior bioadhesive features. For the first time, we engineered three-dimensional printing based swell-able microneedle arrays made out of cross-linked PMVE/MA-PE. Microneedle arrays height and aspect ratio were ranged from 702.5±11.9µm to 726±23.3µm and 3.12±0.20 to 3.29±0.21, respectively. Cross-linked PMVE/MA-PE Microneedle arrays (10-2, 24h) indicated the least height loss, 22.33±4.15%, during axial compression test; whilst, transverse failure of cross-linked PMVE/MA-PE Microneedle arrays was varied from 0.15±0.05 to 0.25±0.04N/needle. In conclusion, we obtained a novel cross-linked polymer system with promising features of drug delivery and bio-analytical applications.

Degradation and metabolism of synthetic plastics and associated products by Pseudomonas sp.: capabilities and challenges.

Synthetic plastics, which are widely present in materials of everyday use, are ubiquitous and slowly-degrading polymers in environmental wastes. Of special interest are the capabilities of microorganisms to accelerate their degradation. Members of the metabolically diverse genus Pseudomonas are of particular interest due to their capabilities to degrade and metabolize synthetic plastics. Pseudomonas species isolated from environmental matrices have been identified to degrade polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyurethane, polyethylene terephthalate, polyethylene succinate, polyethylene glycol and polyvinyl alcohol at varying degrees of efficiency. Here, we present a review of the current knowledge on the factors that control the ability of Pseudomonas sp. to process these different plastic polymers and their by-products. These factors include cell surface attachment within biofilms, catalytic enzymes involved in oxidation or hydrolysis of the plastic polymer, metabolic pathways responsible for uptake and assimilation of plastic fragments and chemical factors that are advantageous or inhibitory to the biodegradation process. We also highlight future research directions required in order to harness fully the capabilities of Pseudomonas sp. in bioremediation strategies towards eliminating plastic wastes.

Bacterial magnetic particles improve testes-mediated transgene efficiency in mice.

Nano-scaled materials have been proved to be ideal DNA carriers for transgene. Bacterial magnetic particles (BMPs) help to reduce the toxicity of polyethylenimine (PEI), an efficient gene-transferring agent, and assist tissue transgene ex vivo. Here, the effectiveness of the BMP-PEI complex-conjugated foreign DNAs (BPDs) in promoting testes-mediated gene transfer (TMGT) in mouse was compared with that of liposome-conjugated foreign DNAs. The results proved that through testes injection, the clusters of BPDs successfully reached the cytoplasm and the nuclear of spermatogenesis cell, and expressed in testes of transgene founder mice. Additionally, the ratio of founder mice obtained from BPDs (88%) is about 3 times higher than the control (25%) (p < 0.05). Interestingly, the motility of sperms recovered from epididymis of the founder mice from BPD group were significantly improved, as compared with the control (p < 0.01). Based on classic breeding, the ratio of transgene mice within the first filial was significantly higher in BPDs compared with the control (73.8% versus 11.6%, p < 0.05). TMGT in this study did not produce visible histological changes in the testis. In conclusion, nano-scaled BPDs could be an alternative strategy for efficiently producing transgene mice in vivo.

Molecular weight-dependent degradation and drug release of surface-eroding poly(ethylene carbonate).

Poly(ethylene carbonate) (PEC) is a unique biomaterial showing significant potential for controlled drug delivery applications. The current study investigated the impact of the molecular weight on the biological performance of drug-loaded PEC films. Following the preparation and thorough physicochemical characterization of diverse PEC (molecular weights: 85, 110, 133, 174 and 196kDa), the degradation and drug release behavior of rifampicin- and bovine serum albumin-loaded PEC films was investigated in vitro (in the presence and absence of cholesterol esterase), in cell culture (RAW264.7 macrophages) and in vivo (subcutaneous implantation in rats). All investigated samples degraded by means of surface erosion (mass loss, but constant molecular weight), which was accompanied by a predictable, erosion-controlled drug release pattern. Accordingly, the obtained in vitro degradation half-lives correlated well with the observed in vitro half-times of drug delivery (R2=0.96). Here, the PEC of the highest molecular weight resulted in the fastest degradation/drug release. When incubated with macrophages or implanted in animals, the degradation rate of PEC films superimposed the results of in vitro incubations with cholesterol esterase. Interestingly, SEM analysis indicated a distinct surface erosion process for enzyme-, macrophage- and in vivo-treated polymer films in a molecular weight-dependent manner. Overall, the molecular weight of surface-eroding PEC was identified as an essential parameter to control the spatial and temporal on-demand degradation and drug release from the employed delivery system.

Bone-specific poly(ethylene sodium phosphate)-bearing biodegradable nanoparticles.

Chemotherapy is the most reliable treatment for osteoporosis and osseous metastases. To facilitate better drug delivery for bone treatments, a novel preparation of polymeric nanoparticles with high affinity to bone has been prepared. Two-step synthesis of cholesteryl-functionalized poly(ethylene sodium phosphate) (Ch-PEPn·Na) was performed via ring-opening polymerization of cyclic phosphoesters and the demethylation. The molecular weight of Ch-PEPn·Na could be well controlled by changing the ratio of cholesterol and cyclic phosphoesters. Because Ch-PEPn·Na exhibits an amphiphilic nature in aqueous media, Ch-PEPn·Na-bearing nanoparticles (PEPn·Na NPs) were prepared by a solvent evaporation technique. The size of the nanoparticles investigated in the current study is approximately 100nm, which was determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Due to the presence of highly water-soluble polymer chains, dispersion of PEPn·Na NPs in aqueous media was stable for at least 1 week. Hemolytic activity of PEPn·Na NPs was found to be low and PEPn·Na NPs did not disintegrate mammalian cell membranes. Additionally, cytotoxicity of PEPn·Na NPs was not observed at concentrations below 100µg/mL. The adsorption of PEPn·Na NPs on hydroxyapatite (HAp) microparticles was studied in comparison with poly(ethylene glycol) nanoparticles (PEG NPs). Both PEPn·Na NPs and PEG NPs adsorbed well onto HAp microparticles in distilled water with binding equilibrium constants (KHAp) for PEPn·Na NPs and PEG NPs of 3.6×106 and 7.9×106, respectively. In contrast, only PEPn·Na NPs adsorbed onto HAp microparticles in a saline phosphate buffer. Moreover, the adsorption of PEPn·Na NPs onto HAp microparticles occurred even in the presence of 1.2mM calcium ions or low-pH media. The affinity of the nanoparticles to bovine bone slices was also studied, with the result that large quantities of adsorbed PEPn·Na NPs were observed on the slices by scanning electron microscope.

Enzymatic hydrolysis of poly(ethylene furanoate).

The urgency of producing new environmentally-friendly polyesters strongly enhanced the development of bio-based poly(ethylene furanoate) (PEF) as an alternative to plastics like poly(ethylene terephthalate) (PET) for applications that include food packaging, personal and home care containers and thermoforming equipment. In this study, PEF powders of various molecular weights (6, 10 and 40kDa) were synthetized and their susceptibility to enzymatic hydrolysis was investigated for the first time. According to LC/TOF-MS analysis, cutinase 1 from Thermobifida cellulosilytica liberated both 2,5-furandicarboxylic acid and oligomers of up to DP4. The enzyme preferentially hydrolyzed PEF with higher molecular weights but was active on all tested substrates. Mild enzymatic hydrolysis of PEF has a potential both for surface functionalization and monomers recycling.

Impact of lipid-induced degradation on the mechanical properties of ultra-high molecular weight polyethylene for joint replacements.

Gamma or electron beam irradiation of ultra-high molecular weight polyethylene (UHMWPE) used in artificial joints for sterilization and/or crosslinking purposes generates free radicals in the material, which causes long-term oxidative degradation of UHMWPE. Recently, another mechanism for the degradation of UHMWPE by the absorption of lipids during in vivo clinical use was proposed. However, knowledge on lipid-induced degradation is quite limited, compared with that on radical-induced degradation. In this study, lipid-induced degradation was simulated using squalene absorption and subsequent accelerated aging, and its impact on the mechanical properties of UHMWPE was evaluated. The simulated lipid-induced degradation caused an increased elastic modulus and decreased elongation with maximum degradation at the surfaces. These results imply that degradation of UHMWPE may occur during in vivo long-term use, even if free radicals are completely eliminated. Therefore, further investigation is required to clarify the impact of lipid-induced degradation on clinical outcomes, such as the wear and fatigue characteristics of UHMWPE components.

Interactions of poly (anhydride) nanoparticles with macrophages in light of their vaccine adjuvant properties.

Understanding how nanoparticles are formed and how those processes ultimately determine the nanoparticles' properties and their impact on their capture by immune cells is key in vaccination studies. Accordingly, we wanted to evaluate how the previously described poly (anhydride)-based nanoparticles of the copolymer of methyl vinyl ether and maleic anhydride (NP) interact with macrophages, and how this process depends on the physicochemical properties derived from the method of preparation. First, we studied the influence of the desolvation and drying processes used to obtain the nanoparticles. NP prepared by the desolvation of the polymers in acetone with a mixture of ethanol and water yielded higher mean diameters than those obtained in the presence of water (250nm vs. 180nm). In addition, nanoparticles dried by lyophilization presented higher negative zeta potentials than those dried by spray-drying (-47mV vs. -35mV). Second, the influence of the NP formulation on the phagocytosis by J774 murine macrophage-like cell line was investigated. The data indicated that NPs prepared in the presence of water were at least three-times more efficiently internalized by cells than NPs prepared with the mixture of ethanol and water. Besides, lyophilized nanoparticles appeared to be more efficiently taken up by J744 cells than those dried by spray-drying. To further understand the specific mechanisms involved in the cellular internalization of NPs, different pharmacological inhibitors were used to interfere with specific uptake pathways. Results suggest that the NP formulations, particularly, nanoparticles prepared by the addition of ethanol:water, are internalized by the clathrin-mediated endocytosis, rather than caveolae-mediated mechanisms, supporting their previously described vaccine adjuvant properties.

Evidence of polyethylene biodegradation by bacterial strains from the guts of plastic-eating waxworms.

Polyethylene (PE) has been considered nonbiodegradable for decades. Although the biodegradation of PE by bacterial cultures has been occasionally described, valid evidence of PE biodegradation has remained limited in the literature. We found that waxworms, or Indian mealmoths (the larvae of Plodia interpunctella), were capable of chewing and eating PE films. Two bacterial strains capable of degrading PE were isolated from this worm's gut, Enterobacter asburiae YT1 and Bacillus sp. YP1. Over a 28-day incubation period of the two strains on PE films, viable biofilms formed, and the PE films' hydrophobicity decreased. Obvious damage, including pits and cavities (0.3-0.4 µm in depth), was observed on the surfaces of the PE films using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The formation of carbonyl groups was verified using X-ray photoelectron spectroscopy (XPS) and microattenuated total reflectance/Fourier transform infrared (micro-ATR/FTIR) imaging microscope. Suspension cultures of YT1 and YP1 (10(8) cells/mL) were able to degrade approximately 6.1 ± 0.3% and 10.7 ± 0.2% of the PE films (100 mg), respectively, over a 60-day incubation period. The molecular weights of the residual PE films were lower, and the release of 12 water-soluble daughter products was also detected. The results demonstrated the presence of PE-degrading bacteria in the guts of waxworms and provided promising evidence for the biodegradation of PE in the environment.

Augmented cellular trafficking and endosomal escape of porous silicon nanoparticles via zwitterionic bilayer polymer surface engineering.

The development of a stable vehicle with low toxicity, high cellular internalization, efficient endosomal escape, and optimal drug release profile is a key bottleneck in nanomedicine. To overcome all these problems, we have developed a successful layer-by-layer method to covalently conjugate polyethyleneimine (PEI) and poly(methyl vinyl ether-co-maleic acid) (PMVE-MA) copolymer on the surface of undecylenic acid functionalized thermally hydrocarbonized porous silicon nanoparticles (UnTHCPSi NPs), forming a bilayer zwitterionic nanocomposite containing free positive charge groups of hyper-branched PEI disguised by the PMVE-MA polymer. The surface smoothness, charge and hydrophilicity of the developed NPs considerably improved the colloidal and plasma stabilities via enhanced suspensibility and charge repulsion. Furthermore, despite the surface negative charge of the bilayer polymer-conjugated NPs, the cellular trafficking and endosomal escape were significantly increased in both MDA-MB-231 and MCF-7 breast cancer cells. Remarkably, we also showed that the conjugation of surface free amine groups of the highly toxic UnTHCPSi-PEI (Un-P) NPs to the carboxylic groups of PMVE-MA renders acceptable safety features to the system and preserves the endosomal escape properties via proton sponge mechanism of the free available amine groups located inside the hyper-branched PEI layer. Moreover, the double layer protection not only controlled the aggregation of the NPs and reduced the toxicity, but also sustained the drug release of an anticancer drug, methotrexate, with further improved cytotoxicity profile of the drug-loaded particles. These results provide a proof-of-concept evidence that such zwitterionic polymer-based PSi nanocomposites can be extensively used as a promising candidate for cytosolic drug delivery.

Synthesis of starch-g-p(DMDAAC) using HRP initiation and the correlation of its structure and sludge dewaterability.

A new cationic starch used as a sludge dewatering agent was prepared by grafting copolymerization of degradation starch and dimethyldiallylammonium chloride (DMDAAC) using horseradish peroxidase/H2O2 initiation. Its chemical structure was characterized by FTIR, (1)H NMR, (13)C NMR, gel permeation chromatography, graft percent, and graft efficiency. The results indicated that its structure was built by grafting the DMDAAC oligomer onto the starch backbone as branched chains, with stronger hydrophobic regions and higher cationic degree. The specific resistance of the filtration and capillary suction time of the sludge conditioned with the cationic starch decreased distinctly, and the sludge water content could be reduced to 50.6% from 97.85%. The dewatering mechanism is proposed based on the surface tension, zeta potential, and microstructure of sludge, which involves stronger hydrophobic regions and cationic groups producing a porous structure within the sludge. The research results may provide valuable ideas for developing high-performance sludge dewatering agents.

Cell surface hydrophobicity: a key component in the degradation of polyethylene succinate by Pseudomonas sp. AKS2.

AIM: Polyethylene succinate (PES) contains hydrolysable ester bonds that make it a potential substitute for polyethylene (PE) and polypropylene (PP). Towards bioremediation of PES, we have already reported that a new strain of Pseudomonas, Pseudomonas sp. AKS2, can efficiently degrade PES and hypothesized that cell surface hydrophobicity plays an important role in this degradation process. In this study, our efforts were targeted towards establishing a correlation between cell surface hydrophobicity and PES degradation. METHODS AND RESULTS: We have manipulated cell surface hydrophobicity of AKS2 by varying concentrations of glucose and ammonium sulphate in the growth medium and subsequently examined the extent of PES degradation. We observed an increase in PES degradation by AKS2 with an increase in cell surface hydrophobicity. The increased surface hydrophobicity caused an enhanced biofilm formation on PES surface that resulted in better polymer degradation. CONCLUSION: The current study establishes a direct correlation between cell surface hydrophobicity of an organism and its potential to degrade a nonpolar polymer like PES. SIGNIFICANCE AND IMPACT OF THE STUDY: Cell surface hydrophobicity manipulation can be used as an important strategy to increase bioremediation of nonpolar polymer like PES.