Short-chain Poly Research Articles

Embryonic 6:2 Fluorotelomer Alcohol Exposure Disrupts the Blood‒Brain Barrier by Causing Endothelial‒to‒Mesenchymal Transition in the Male Mice.

6:2 Fluorotelomer alcohol (6:2 FTOH) is a raw material used in the manufacture of short-chain poly- and perfluoroalkyl substances. Our previous study revealed that gestational exposure to 6:2 FTOH can impair blood‒brain barrier (BBB) function in offspring, accompanied by anxiety-like behavior and learning memory deficits. The aim of this study was to further investigate the specific mechanism by which maternal exposure to 6:2 FTOH resulted in impaired BBB function in offspring mice. Pregnant mice were orally administered different doses of 6:2 FTOH (0, 5, 25, and 125mg/kg/day) from gestation day 8.5 until delivery. These results confirmed that maternal 6:2 FTOH exposure impaired BBB function and disrupted the brain immune microenvironment. Subsequent investigations revealed that endothelial-to-mesenchymal transition (EndMT) in the cerebral microvascular endothelium of offspring may be the mechanism mediating functional disruption of the BBB. Mechanistic studies revealed that exposure to 6:2 FTOH upregulated ETS proto-oncogene 1 (ETS1) expression via the tumor necrosis factor-α/extracellular signal-regulated kinase 1/2 signaling pathway, which mediated disturbances in energy metabolism, leading to impaired actin dynamics and subsequently triggering the EndMT phenotype. This is the first finding indicating that gestational 6:2 FTOH exposure caused functional impairment of the BBB through ETS1-mediated EndMT in cerebral microvascular endothelial cells, potentially providing novel insight into the environmental origins of neurodevelopmental disorders.

Underlying Roles of Polyol Additives in Promoting CO2 Capture in PEI/Silica Adsorbents.

Solid-supported amines having low molecular weight branched poly(ethylenimine) (PEI) physically impregnated into porous solid supports are promising adsorbents for CO2 capture. Co-impregnating short-chain poly(ethylene glycol) (PEG) together with PEI alters the performance of the adsorbent, delivering improved amine efficiency (AE, mol CO2 sorbed/mol N) and faster CO2 uptake rates. To uncover the physical basis for this improved gas capture performance, we probe the distribution and mobility of the polymers in the pores via small angle neutron scattering (SANS), solid-state NMR, and molecular dynamic (MD) simulation studies. SANS and MD simulations reveal that PEG displaces wall-bound PEI, making amines more accessible for CO2 sorption. Solid-state NMR and MD simulation suggest intercalation of PEG into PEI domains, separating PEI domains and reducing amine-amine interactions, providing potential PEG-rich and amine-poor interfacial domains that bind CO2 weakly via physisorption while providing facile pathways for CO2 diffusion. Contrary to a prior literature hypothesis, no evidence is obtained for PEG facilitating PEI mobility in solid supports. Instead, the data suggest that PEG chains coordinate to PEI, forming larger bodies with reduced mobility compared to PEI alone. We also demonstrate promising CO2 uptake and desorption kinetics at varied temperatures, facilitated by favorable amine distribution.

Determination of MCPA in environmental samples using an analytical on-line system based on imprinted poly[2-(3-butenyl)-2-oxazoline] and ambient ionization mass spectrometry

Monitoring and quantifying organic chemicals in the environment play a vital role in understanding their behavior and ensuring environmental safety. MCPA (2-methyl-4-chlorophenoxyacetic acid) is a commonly used phenoxy herbicide that poses potential risks to aquatic life. In this study, we present an innovative analytical approach for MCPA quantification, employing molecularly imprinted polymers (MIPs) for selective extraction and ambient plasma mass spectrometry for direct on-line analysis. To synthesize functional MIPs, we employed a post-polymerization strategy based on a thiol-ene click reaction conducted on a short-chain poly[2-(3-butenyl)-2-oxazoline] (poly(ButenOx)) that allowed attachment of 3-mercaptopropionic acid (MPA) to polymer side chains. The incorporation of MPA groups into polymer structure enabled the attainment of elevated maximum adsorption capacities and enhanced selectivity towards MCPA. Utilizing a specially designed ambient plasma mass spectrometry setup, we successfully quantified MCPA in water samples, achieving significantly improved detection limits compared to conventional solution-based analysis, whereas the quantification of MCPA in real-life river water samples demonstrated excellent recoveries. In conclusion, this novel analytical method employing MIPs and ambient plasma mass spectrometry provides an effective and sensitive approach for accurate MCPA detection in environmental water samples. The technique holds promise for facilitating reliable monitoring and management of MCPA levels in aquatic ecosystems.

Explosives removal and quantification using porous adsorbents based on poly(2-oxazoline)s with various degree of functionalization

Polymeric porous adsorbents are reported for removal of explosives, namely picric acid, 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN) and their subsequent quantification using direct analysis with ambient plasma mass spectrometry. The adsorbents are obtained by functionalization of short-chain poly(2-oxazoline)s with methyl ester side chains using 4-(aminomethyl)pyridine with a degree of functionalization equal to 0, 5, 10, and 20%. The subsequent step consist of cross-linking using a high internal phase emulsion procedure by further side-chain amidation with diethylenetriamine as crosslinker. Picric acid, RDX, and PETN were chosen as the model compounds as they belong to three different groups of explosives, in particular nitroaromatics, nitroamines, and nitrate esters, respectively. The adsorption isotherms, kinetics, as well as the influence of pH and temperature on the adsorption process was investigated. The porous adsorbents showed the highest maximum adsorption capacity towards picric acid, reaching 334 mg g−1, while PETN (80 mg g−1) and RDX (17.4 mg g−1) were less efficiently adsorbed. Subsequent quantification of the adsorbed explosives is performed by a specially designed ambient mass spectrometry setup equipped with a thermal heater. The obtained limits of detection were found to be 20-times improved compared to direct analysis of analyte solutions. The effectiveness of the proposed analytical setup is confirmed by successful quantification of the explosives in river water samples. The research clearly shows that functional porous adsorbents coupled directly with ambient mass spectrometry can be used for rapid quantification of explosives, which can be, e.g., used for tracking illegal manufacturing sites of these compounds.

Medium chain length polyhydroxyalkanoates as potential matrix materials for peripheral nerve regeneration.

Polyhydroxyalkanoates are natural, biodegradable, thermoplastic and sustainable polymers with a huge potential in fabrication of bioresorbable implantable devices for tissue engineering. We describe a comparative evaluation of three medium chain length polyhydroxyalkanoates (mcl-PHAs), namely poly(3-hydroxyoctanoate), poly(3-hydroxyoctanoate-co-3-hydoxydecanoate) and poly(3-hydroxyoctanoate-co-3-hydroxydecanoate-co-3-hydroxydodecanoate), one short chain length polyhydroxyalkanoate, poly(3-hydroxybutyrate), P(3HB) and synthetic aliphatic polyesters (polycaprolactone and polylactide) with a specific focus on nerve regeneration, due to mechanical properties of mcl-PHAs closely matching nerve tissues. In vitro biological studies with NG108-15 neuronal cell and primary Schwann cells did not show a cytotoxic effect of the materials on both cell types. All mcl-PHAs supported cell adhesion and viability. Among the three mcl-PHAs, P(3HO-co-3HD) exhibited superior properties with regards to numbers of cells adhered and viable cells for both cell types, number of neurite extensions from NG108-15 cells, average length of neurite extensions and Schwann cells. Although, similar characteristics were observed for flat P(3HB) surfaces, high rigidity of this biomaterial, and FDA-approved polymers such as PLLA, limits their applications in peripheral nerve regeneration. Therefore, we have designed, synthesized and evaluated these materials for nerve tissue engineering and regenerative medicine, the interaction of mcl-PHAs with neuronal and Schwann cells, identifying mcl-PHAs as excellent materials to enhance nerve regeneration and potentially their clinical application in peripheral nerve repair.

Plasma-Assisted Degradation of Short-Chain Poly- and Perfluoroalkyl Substances (Pfas): Perfluorobutane Sulfonate (Pfbs)

Plasma-Assisted Degradation of Short-Chain Poly- and Perfluoroalkyl Substances (Pfas): Perfluorobutane Sulfonate (Pfbs)

Trp2 Peptide-Assembled Nanoparticles with Intrinsically Self-Chelating 64Cu Properties for PET Imaging Tracking and Dendritic Cell-Based Immunotherapy against Melanoma.

Dendritic cell-based immunotherapy, in which the antigen is effectively delivered to dendritic cells and then the dendritic cells stimulated by the antigen migrate to draining lymph nodes (DLNs) to induce the CD8+ T-cell immune response, shows great promise for tumor immunotherapy. In this study, we used coassembled nanoparticles formed by Trp2 antigen and the conjugates of short-chain poly(ethylene glycol) (PEG) and pyropheophorbide-A (PPa) (Trp2/PPa-PEGm) to deliver Trp2 to DCs. Intrinsically self-chelating 64Cu of coassemblies could be used to sensitively image the migration of DCs in vivo by positron emission tomography (PET) imaging. The coassemblies of the Trp2 antigen were efficiently engulfed by DCs without causing DC cytotoxicity in vitro and induced DC maturation. After injection of DCs labeled by coassemblies of the Trp2 antigen, the homing of DCs to DLNs in vivo could be sensitively observed by PET imaging. The C57BL/6 mice injected with DCs containing the Trp2/PPa-PEGm NP showed antigen-specific immune responses including enhanced interferon-γ (IFN-γ) production, splenocyte proliferation, and percentage of IFN-γ-secreting CD8+ T cells. In addition, C57BL/6 mice inoculated with B16-F10 tumor cells showed delayed tumor growth after immunization with the Trp2/PPa-PEGm NP-labeled DC vaccine and enhanced infiltration of CD8+ T cells in tumors.

Enhanced dielectric properties of poly(dimethyl siloxane) bimodal network percolative composite with chemically modified graphene

Bimodal network composite was prepared using a two-step method containing graphene modified by γ-(2, 3-epoxypropoxy) propyl trimethoxysilane (KH560), short chain poly(dimethyl siloxane) (CS-PDMS) and long chain poly(dimethyl siloxane) filled with treated fumed silica (CL-h-PDMS). A series of composites with different filler contents (including reduced graphene oxide and reduced graphene oxide grafted with KH560, referred to rGO and KrGO, respectively) were prepared to explore their percolation thresholds (fc). We discover that the dielectric constant and loss of 1.32 vol% KrGO/h-PDMS composite were 18.8 and 0.13 at 102 Hz before fc, respectively, which was 2.1 and 0.12 times that of rGO/h-PDMS, and 6.6 and 2.1 times that of pure h-PDMS. The origin is that KH560 insulting layer increases the interlayer distance of graphene sheets to cut down the leakage current. In addition, the modulus of 1.32 vol% KrGO/h-PDMS is less than 3 MPa.

A simplified fabric phase sorptive extraction method for the determination of amphetamine drugs in water samples using liquid chromatography-mass spectrometry.

Fabric phase sorptive extraction (FPSE) can directly extract the target analytes and simultaneously determine many similar substances from complicated sample matrices. Also, it has very high chemical stability. Therefore, we used fabric phase sorptive extraction to analyze three amphetamine drugs (amphetamine (AM), methamphetamine (MAM), and 3,4-methylenedioxymethamphetamine (MDMA)) in water. This was coupled with ultrahigh-performance liquid chromatography and tandem mass spectrometry. The effects of different sorbent chemistries such as sorption time, ratios of back-extraction solvents, back-extraction time, and the salt effect on the extraction efficiency were studied; the optimum operation conditions were determined. Medium polarity polar polymer-coated FPSE media were created using short-chain poly (tetrahydrofuran) (PTHF). This is the most efficient extraction media for the analytes of interest. Under the optimized conditions, the linear range of the three amphetamine drugs were 0.1–150.0 (AM, MAM) and 0.5–200 ng mL−1 (MDMA). The correlation coefficients (γ) were 0.9947 (AM), 0.9925 (MAM), and 0.9918 (MDMA). The detection limits (LOD) were 0.025 ng mL−1 for AM, 0.029 ng mL−1 for MAM, and 0.01 ng mL−1 for MDMA. The corresponding limit of quantification values (LOQ) were 0.083 ng mL−1, 0.097 ng mL−1, and 0.031 ng mL−1, respectively. The recoveries were 73.4–91.6%, 82.6–95.4%, and 92.7–95.3%, respectively, and the relative standard deviations (RSD) were 1.65–6.88%, 1.38–6.11%, and 1.58–7.34%, respectively. Moreover, our method can be successfully applied for the analysis of amphetamines in wastewater samples, and at the same time, lays the foundation for the future detection of such substances.

Enzymatic Characteristics of a Polyphosphate/ATP-NAD Kinase, PanK, from Myxococcus xanthus.

NAD kinase is a crucial enzyme for production of NADP+. Myxococcus xanthus is a gram-negative soil bacterium that forms fruiting bodies and spores under starvation, and it accumulates polyphosphate (poly(P)) during early development. We found that M. xanthus NAD kinase (PanK) utilized both ATP and poly(P) as phosphoryl donors; therefore, PanK was designated as a poly(P)/ATP-NAD kinase. Unlike other poly(P)/ATP-NAD kinases, PanK hardly exhibited NADH kinase activity. The NAD kinase activity of PanK was inhibited by NADPH, but not NADH. Replacement of Thr-90 in the GGDGT motif of PanK with Asn decreased both ATP- and poly(P)-dependent NAD kinase activities; however, poly(P)-dependent NAD kinase activity was further decreased by approximately 6- to 10-fold compared with ATP-dependent NAD kinase activity, suggesting that Thr-90 in the GGDGT motif of PanK may be important for poly(P) utilization. PanK preferred ATP and short-chain poly(P) as phosphoryl donors. The Km of PanK for ATP, poly(P)4, and poly(P)10-15 was 0.66mM, 0.08mM, and 0.71mM, respectively, and the catalytic efficiency (kcat/Km) for poly(P)4 was 2.4-fold higher than that for ATP, suggesting that M. xanthus under starvation conditions may be able to efficiently generate NADP+ using PanK, ATP, and poly(P).

Silk Sericin Semi-interpenetrating Network Hydrogels Based on PEG-Diacrylate for Wound Healing Treatment

Silk sericin (SS) from the Bombyx mori silk cocoons has received much attention from biomedical scientists due to its outstanding properties, such as antioxidant, antibacterial, UV-resistant, and ability to release moisturizing factors. Unmodified SS does not self-assemble strongly enough to be used as a hydrogel wound dressing. Therefore, there is a need for suitable stabilization techniques to interlink the SS peptide chains or strengthen their structural cohesion. Here, we reported a method to form a silk semi-interpenetrating network (semi-IPN) structure through reacting with the short-chain poly(ethylene glycol) diacrylate (PEGDA) in the presence of a redox pair. Various hydrogels were prepared in aqueous media at the final SS/PEGDA weight percentages of 8/92, 15/85, and 20/80. Results indicated that all semi-IPN samples underwent a sol-gel transition within 70 min. The equilibrium water content (EWC) for all samples was found to be in the range of 70-80%, depending on the PEGDA content. Both the gelation time and the sol fraction decreased with the increased PEGDA content. This was due to the tightened network structure formed within the hydrogel matrices. Among all hydrogel samples, the 15/85 (SS/PEGDA) hydrogel displayed the maximum compressive strength (0.66 MPa) and strain (7.15%), higher than those of pure PEGDA. This implied a well-balanced molecular interaction within the SS/PEGDA/water systems. Based on the direct and indirect MTS assay, the 15/85 hydrogel showed excellent in vitro biocompatibility towards human dermal fibroblasts, representing a promising material for biomedical wound dressing in the future. A formation of a semi-IPN structure has thus proved to be one of the best strategies to extend a practical limit of using SS hydrogels for wound healing treatment or other biomedical hydrogel matrices in the future.

Self-Assembly of Short Chain Poly- N-isopropylacrylamid Induced by Superchaotropic Keggin Polyoxometalates: From Globules to Sheets.

We show here for the first time that short chain poly( N-isopropylacrylamide) (PNIPAM), one of the most famous thermoresponsive polymers, self-assembles in water to form (i) discrete nanometer-globules and (ii) micrometric sheets with nm-thickness upon addition of the well-known Keggin-type polyoxometalate (POM) H3PW12O40 (PW). The type of self-assembly is controlled by PW concentration: at low PW concentrations, PW adsorbs on PNIPAM chains to form globules consisting of homogeneously distributed PWs in PNIPAM droplets of several nm in size. Upon further addition of PW, a phase transition from globules to micrometric sheets is observed for PNIPAMs above a polymer critical chain length, between 18 and 44 repeating units. The thickness of the sheets is controlled by the PNIPAM chain length, here from 44 to 88 repeating units. The PNIPAM sheets are electrostatically stabilized PWs accumulated on each side of the sheets. The shortest PNIPAM chain with 18 repeating units produces PNIPAM/PW globules with 5-20 nm size but no sheets. The PW/PNIPAM self-assembly arises from a solvent mediated mechanism associated with the partial dehydration of PW and of the PNIPAM, which is related to the general propensity of POMs to adsorb on neutral hydrated surfaces. This effect, known as superchaotropy, is further highlighted by the significant increase in the lower critical solubilization temperature (LCST) of PNIPAM observed upon the addition of PW in the mM range. The influence of the POM nature on the self-assembly of PNIPAM was also investigated by using H4SiW12O40 (SiW) and H3PMo12O40 (PMo), i.e. changing the POM's charge density or polarizability in order to get deeper understanding on the role of electrostatics and polarizability in the PNIPAM self-assembly process. We show here that the superchaotropic behavior of POMs with PNIPAM polymers enables the formation and the shape control of supramolecular organic-inorganic hybrids.

Effect of Poly(ethylene glycol) Grafting Density on Methylcellulose Fibril Formation

We investigate the effect of short-chain poly(ethylene glycol) (PEG) graft density on the formation of methylcellulose (MC) fibrils at elevated temperatures. Thiol–ene click chemistry was used to systematically graft 800 and 2000 g/mol PEG onto the backbone of allylated MC, with a wide range of grafting densities from 0.7% to 33%. As determined from light scattering, grafting leads to an increase in the persistence length of this semiflexible copolymer, by as much as a factor of 10. Upon heating, SAXS and AFM studies show that fibril formation is suppressed at around 10% grafting density for shorter PEG grafts, corresponding to persistence lengths about ∼22 nm. For longer grafts fibril formation is suppressed at 7% grafting density, at around the same ∼22 nm persistence length. The radius of the fibrils increases with the square root of the persistence length of the chains, which is consistent with a theory for the radius of twisted chains. The ability to form networks at 80 °C is highly correlated to the...

Burkholderia sacchari DSM 17165: A source of compositionally-tunable block-copolymeric short-chain poly(hydroxyalkanoates) from xylose and levulinic acid

Burkholderia sacchari was used to produce poly-3-hydroxybutyrate-co-3-hydroxyvalerate block copolymers from xylose and levulinic acid. Levulinic acid was the preferred substrate resulting in 3-hydroxyvalerate (3HV) contents as high as 95 mol% at 24 h. The 3HB:3HV ratios were controlled by the initial levulinic acid media concentration and fermentation length. Higher levulinic acid concentrations and longer durations, resulted in polymers with two glass transition temperatures, each approximating those associated with poly-3HB and poly-3HV. 13C NMR confirmed the presence of high concentrations of 3HB-3HB and 3HV-3HV homopolymeric dyads, while mass spectrometry of the partial hydrolysis products did not conform to Bernoullian statistics for randomness, confirming block sequences. MS/MS analysis of specific oligomers showed the mass-loss of 86 amu (a 3HB unit) and 100 amu (a 3HV unit) attesting to some randomness within the polymers. This study verifies the potential for producing Poly-3HB-block-3HV copolymers from inexpensive biorenewable feedstocks without sequential addition of carbon sources.

Developing heat conduction pathways through short polymer chains in a hydrogen bonded polymer system

In the past couple of decades, high thermally conductive fillers are extensively used to develop thermally conductive polymer based composites. Such conventional methods suffer from wide variety of problems especially related to fabrication, high-cost, poor mechanical properties etc. Though covalent bonds in single polymer chain can lead to very high thermal conduction, it is irony that bulk polymers are thermal insulators due to significant phonon scattering. In this work, we have shown how by engineering intermolecular interaction within the polymer chain, one can create continuous thermal network which in turn drives thermal conduction in polymer without using any traditional fillers. Thermal conduction pathways were introduced in a blend film of long chain polymer Poly (vinyl alcohol) (PVA) and short chain Poly (ethylene glycol) (PEG). Thermal conductivity enhancement of around 1.6 times of neat polymer was achieved. The critical factor responsible for thermal conduction in these films was found to be homogeneous distribution of “thermal bridges” formed by hydrogen bonding between PVA and short PEG chain. Reduction in thermal conductivity was observed when PVA blend film with longer PEG chain, which is mainly due to poor thermal bridges distribution and chain agglomeration. This work presents a fascinating yet promising non-conventional method to make thermally conductive polymer based material without using traditional fillers for thermal management applications.

Response of block copolyelectrolyte complexes to addition of ionic surfactants

Polyelectrolyte complex formation of a long chain poly(sodium styrene sulfonate) (NaPSS) with short chain poly(vinylbenzyltrimethylammonium chloride) homopolymer (pVBTA) and block copolymers (PEG-b-pVBTA) was investigated. The effect of the PEG chain and the pVBTA block length was studied on the complex formation. Then the exchange of the complex bound pVBTA for cetyltrimethylammonium bromide (CTAB) was studied using complexes that contained excess of pVBTA segments. First we characterized the effect of ionic strength on the complex stability. Then we studied how the addition of CTAB affects the stability of the complexes with increasing ionic strength. We found that three ionic strength ranges could be distinguished. In the lowest ionic strength range, the formation of stable mixed complexes could be observed. In the intermediate ionic strength range the pVBTA polymer was mostly substituted by CTAB, leading to the aggregation and precipitation of the complexes under the investigated conditions. Finally, at the highest ionic strength the formation of equilibrium NaPSS/CTAB complexes could be hypothesized.

Fabric phase sorptive extraction as a reliable tool for rapid screening and detection of freshness markers in oranges

A simple, fast and sensitive analyte extraction method based on fabric phase sorptive extraction (FPSE) followed by gas chromatography-mass spectrometry (GC–MS) and ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry (UPLC–QTOF–MS) analysis was developed for the analysis of 12 volatile compounds that represent most of the principal chemical families possessing different polarities and volatilities. Five FPSE media coated with different sol-gel sorbent chemistries having different polarities and selectivities were studied: long chain poly(dimethylsiloxane) (PDMS), short chain poly(tetrahydrofuran) (PTHF), Carbowax 20M (CW20M), short chain poly(dimethyl siloxane) (SC PDMS) and polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer (PEG-PPG-PEG). CW20M coated FPSE media was found to be the most efficient extraction media for the analytes of interest in the intended study. The developed methodology was applied to the analysis of orange juice obtained from fresh oranges and oranges after storing at 5°C for two months in order to identify the best chemical markers, both volatiles and non-volatiles, attributed to the freshness of orange. For this purpose, aliquots of the same juice extracts were analysed by GC–MS as well as by UPLC–QTOF–MS. Monoterpenes and terpenoids, such as terpinene, citronellal or estragole were among the volatile compounds that endured the biggest decrease after the extended storage period. Three non-volatile compounds including one amide (subaphyllin) and two flavanoids (tangeretin and nobiletin) also showed a clear decrease in signal intensity (>70%) after orange stored for two months.

Fabric phase sorptive extraction of selected penicillin antibiotic residues from intact milk followed by high performance liquid chromatography with diode array detection.

Fabric phase sorptive extraction (FPSE), a novel sorbent-based microextraction method, was evaluated as a simple and rapid strategy for the extraction of four penicillin antibiotic residues (benzylpenicillin, cloxacillin, dicloxacillin and oxacillin) from cows' milk, without prior protein precipitation. Time-consuming solvent evaporation and reconstitution steps were eliminated successfully from the sample preparation workflow. FPSE utilizes a flexible fabric substrate, chemically coated with sol-gel derived, highly efficient, organic-inorganic hybrid sorbent as the extraction medium. Herein short-chain poly(ethylene glycol) provided optimum extraction sensitivity for the selected penicillins, which were analysed using an RP-HPLC method, validated according to the European Decision 657/2002/EC. The limit of quantitation was 10μg/kg for benzylpenicillin, 20μg/kg for cloxacillin, 25μg/kg dicloxacillin and 30μg/kg oxacillin. These are a similar order of magnitude with those reported in the literature and (with the exception of benzylpenicillin) are less than the maximum residue limits (MRL) set by European legislation.

Structural investigation of cell wall polysaccharides of Lactobacillus delbrueckii subsp. bulgaricus 17

Lactobacilli are valuable strains for commercial (functional) food fermentations. Their cell surface-associated polysaccharides (sPSs) possess important functional properties, such as acting as receptors for bacteriophages (bacterial viruses), influencing autolytic characteristics and providing protection against antimicrobial peptides. The current report provides an elaborate molecular description of several surface carbohydrates of Lactobacillus delbrueckii subsp. bulgaricus strain 17. The cell surface of this strain was shown to contain short chain poly(glycerophosphate) teichoic acids and at least two different sPSs, designated here as sPS1 and sPS2, whose chemical structures were examined by 2D nuclear magnetic resonance spectroscopy and methylation analysis. Neutral branched sPS1, extracted with n-butanol, was shown to be composed of hexasaccharide repeating units (-[α-d-Glcp-(1-3)-]-4-β-l-Rhap2OAc-4-β-d-Glcp-[α-d-Galp-(1-3)]-4-α-Rhap-3-α-d-Galp-), while the major component of the TCA-extracted sPS2 was demonstrated to be a linear d-galactan with the repeating unit structure being (-[Gro-3P-(1-6)-]-3-β-Galf-3-α-Galp-2-β-Galf-6-β-Galf-3-β-Galp-).

Synthesis of ultrastable copper sulfide nanoclusters via trapping the reaction intermediate: potential anticancer and antibacterial applications.

Copper-based nanomaterials have broad applications in electronics, catalysts, solar energy conversion, antibiotics, tissue imaging, and photothermal cancer therapy. However, it is challenging to prepare ultrasmall and ultrastable CuS nanoclusters (NCs) at room temperature. In this article, a simple method to synthesize water-soluble, monodispersed CuS NCs is reported based on the strategy of trapping the reaction intermediate using thiol-terminated, alkyl-containing short-chain poly(ethylene glycol)s (HS-(CH2)11-(OCH2CH2)6-OH, abbreviated as MUH). The MUH-coated CuS NCs have superior stability in solutions with varied pH values and are stable in pure water for at least 10 months. The as-prepared CuS NCs were highly toxic to A549 cancer cells at a concentration of higher than 100 μM (9.6 μg/mL), making them be potentially applicable as anticancer drugs via intravenous administration by liposomal encapsulation or by direct intratumoral injection. Besides, for the first time, CuS NCs were used for antibacterial application, and 800 μM (76.8 μg/mL) CuS NCs could completely kill the E. coli cells through damaging the cell walls. Moreover, the NCs synthesized here have strong near-infrared (NIR) absorption and can be used as a candidate reagent for photothermal therapy and photoacoustic imaging. The method of trapping the reaction intermediate for simple and controlled synthesis of nanoclusters is generally applicable and can be widely used to synthesize many metal-based (such as Pt, Pd, Au, and Ag) nanoclusters and nanocrystals.