Polystyrene Sulphonate Research Articles

Encapsulation of β-Galactosidase into Polyallylamine/Polystyrene Sulphonate Polyelectrolyte Microcapsules.

More than half of the global population is unable to consume dairy products due to lactose intolerance (hypolactasia). Current enzyme replacement therapy methods are insufficiently effective as a therapeutic approach to treating lactose intolerance. The encapsulation of β-galactosidase in polyelectrolyte microcapsules by using the layer-by-layer method could be a possible solution to this problem. In this study, adsorption and co-precipitation methods were employed for encapsulating β-galactosidase in polyelectrolyte microcapsules composed of (polyallylamine /polystyrene sulphonate)₃. As a result, the co-precipitation method was chosen for β-galactosidase encapsulation. The adsorption method permits to encapsulate six times less enzyme compared with the co-precipitation method; the β-galactosidase encapsulated via the co-precipitation method released no more than 20% of the initially encapsulated enzyme in pH 2 or 1 M NaCl solutions. In contrast, when using the sorption method, about 100% of the initially encapsulated enzyme was released from the microcapsules under the conditions described above. The co-precipitation method effectively prevents the complete loss of enzyme activity after 2 h of incubation in a solution with pH 2 while also alleviating the adverse effects of ionic strength. Consequently, the encapsulated form of β-galactosidase shows promise as a potential therapeutic agent for enzyme replacement therapy in the treatment of hypolactasia.

Enhanced Carrier Selectivity and Superior Passivation in Cost‐Effective Heterogeneous Hybrid Transport Layers for Next Generation Silicon Solar Cells

AbstractHybrid hole transport layers (HHTLs) consisting of‐a low‐cost, low‐temperature, dopant‐free, organic, hole‐selective poly(3,4‐ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) and an inorganic homogenous tunnel oxides (HoTOs), such as SiOx, TiOx, and AlOx have allowed significant improvements in carrier selectivity as well as in power and cost efficiency. These key parameters can be further improved by introducing heterogeneous tunnel oxides (HeTOs), formed of two different inorganic oxides. This work examines the potential of heterogeneous HHTLs and their impact on passivation as well as on the interfacial properties in silicon solar cells. HeTOs of SiOx/TiOx and SiOx/AlOx with negative fixed charge are studied and optimized. A heterogeneous HHTL with AlOx (>1.5 nm) resulted in a high lifetime (1.2 ms), low surface recombination velocity, and improved surface band bending at the interface due to the presence of higher negative fixed charge (1012 cm−2) within these layers. The passivation properties further improved on light soaking and annealing due to oxidation of PSS and AlOx/SiOx. Overall, these HHTLs demonstrated a hole selectivity (S10) of 12.5 and very high efficiencies up to of 26.1%, surpassing homogenous‐SiOx/PEDOT:PSS by 1.4%.

Stable, Conductive, Adhesive Polymer Patterning Inside a Microfluidic Chamber for Endothelial Cell Alignment

AbstractEndothelial cells (ECs) line the inner walls of blood vessels, respond to shear stress by elongating in the direction of flow. Engineering aligned ECs in vitro is essential for modeling human vascular diseases and for drug testing. Current microfluidic approaches mainly rely on unidirectional laminar flow, uniform coating of surfaces to improve cellular adhesion or alteration of the surface topography. Challenges persist due to shear stress‐induced changes in cellular behavior, especially in complex multicellular environments and the time needed for the cells to align and polarize inside the microfluidic conduits. Generally, protein coating processes and physical treatments are also not compatible with the steps required for the assembly of microfluidic devices. This approach employs aerosol jet printing (AJP) to precisely pattern poly(3,4‐ethylenedioxythiophene) polystyrene sulphonate (PEDOT:PSS) within microfluidic chambers in a single step. It is shown that the PEDOT:PSS is biocompatible and facilitates EC adhesion, patterning, elongation, and alignment. Under capillary flow, the cells retain their pattern‐induced morphology over 7 d, confirming the efficacy of the approach in promoting cellular organization, eliminating the need for external pumps. Furthermore, it is demonstrated that the PEDOT:PSS pattern retains structural integrity and electrical stability following oxygen plasma treatment, required for assembling of fully enclosed microfluidic devices.

Interaction between methyl red and cetyltrimethylammonium bromide under the influence of sodium polystyrene sulphonate in ethanol-water binary solvent systems: A spectrophotometric investigation

This research aims to comprehensively investigate and analyze the UV–visible spectroscopic behavior of the methyl red (MR)-cetyltrimethylammonium bromide (CTAB) system under the influence of sodium polystyrene sulfonate (NaPSS) in aqueous and different volume fractions (v.f.) of ethanol (EtOH)–H2O (0.1, 0.2, and 0.3) at 298.15 ± 0.2 K. In EtOH–H2O solvent systems, the triple interactions of dyes-surfactants-polyelectrolyte (DSP) complex systems are entirely novel. MR interacts with CTAB in NaPSS in the binary solvent media (0.1, 0.2, and 0.3 v.f. of EtOH–H2O) resulting in the formation of ion-pairs at very low CTAB concentrations, far below their apparent critical micelle concentration (CMC*) reducing the absorbance, and the new complexes above the CMC* due to solubilization of the MR into CTAB micelles observed by distinct spectral shifts. The CMC* values obtained from spectroscopic data increase in the order: (CMC*)water< (CMC*)0.1< (CMC*)0.2< (CMC*)0.3. This is because of the reduced polarity or dielectric constant and increased degree of water structure disruption around the hydrophobic chains of CTAB, where micelle formation occurs at somewhat higher concentrations. The Gibbs energy of micellization (ΔGmo) increases in the order: (ΔGmo=−16.89)water <(ΔGmo=−16.17)0.1<(ΔGmo=−15.62)0.2<(ΔGmo=−15.38)0.3, which further supports the inhibitory effect of increasing ethanol content towards micellization. In the post-micellar region, the decrease in hydrophobic interactions and an increase in electrostatic interactions lead to a rise in the overall binding constant value. This means that, when NaPSS is present, the stronger electrostatic interactions in the post-micellar region contribute significantly to the increased binding of CTAB micelles with MR. The tautomeric activity of MR and the solvent composition played a prime role in affecting the interaction mechanism, as evidenced by the blue and red spectral shifts.

Hyperkalaemia in Cardiological Patients: New Solutions for an Old Problem.

Hyperkalaemia is one of the most common electrolyte disorders in patients with cardiovascular disease (CVD). The true burden of hyperkalaemia in the real-world setting can be difficult to assess, but in population-based cohort studies up to 4 in 10 patients developed hyperkalaemia. In addition to drugs interfering with potassium metabolism and food intake, several conditions can cause or worsen hyperkalaemia, such as advanced age, diabetes, and chronic kidney disease. Mortality, cardiovascular morbidity, and hospitalisation are higher in patients with hyperkalaemia. Hyperkalaemia represents a major contraindication or a withholding cause for disease-modifying therapies like renin-angiotensin-aldosterone inhibitors (RAASi), mainly mineralocorticoid receptor antagonists. Hyperkalaemia can be also classified as acute and chronic, according to the onset. Acute hyperkalaemia is often a life-threatening emergency requiring immediate treatment to avoid lethal arrhythmias. Therapy goal is cell membrane stabilisation by calcium administration, cellular intake, shift of extracellular potassium to the intracellular space (insulin, beta-adrenergic agents, sodium bicarbonate), and increased elimination with diuretics or dialysis. Chronic hyperkalaemia was often managed with dietary counselling to prevent potassium-rich food intake and tapering of potassium-increasing drugs, mostly RAASi. Sodium polystyrene sulphonate, a potassium binder, was the only therapeutic option. Recently, new drugs such as patiromer and sodium zirconium cyclosilicate give new opportunities for the treatment of hyperkalaemia, as they proved to be safe, well tolerated, and effective. Aim of this review is to describe the burden of hyperkalaemia in cardiovascular patients, its direct and indirect effects, and the therapeutic options now available in the acute and chronic setting.

Self-assembly, cytocompatibility, and interactions of desmopressin with sodium polystyrene sulfonate.

Peptide-polymer systems hold strong potential for applications in nanotherapeutics. Desmopressin, a synthetic analogue of the antidiuretic hormone arginine vasopressin, may serve as a valuable case of study in this context since it is a first-line treatment for disorders affecting water homeostasis, including diabetes insipidus. It also has an established use as a hemostatic agent in von Willebrand disease, and recently, its repurposing has been suggested as a neoadjuvant in the treatment of certain types of cancer. Despite its well-documented clinical uses, studies on the supramolecular organization of desmopressin and its association with polymers remain scarce, limiting the therapeutic benefits of these nanostructured arrays. Here, we investigate the self-assembly of desmopressin and its association with sodium polystyrene sulphonate (NaPSS), a potassium-binding polymer used to treat hyperkalemia. Using structural techniques such as small-angle X-ray scattering (SAXS), cryogenic transmission electron microscopy (cryo-TEM), and atomic force microscopy combined with infrared nanospectroscopy (AFM-IR), we identified that desmopressin associates with NaPSS to form hybrid fibrillar nanoassemblies characterized by β-turn enriched domains and the appearance of β-sheet content. In vitro cytotoxicity assays conducted on breast cancer cell lines MCF-7 and MDA-MB-231 showed that NaPSS/desmopressin complexes are well-tolerated by the non-metastatic MCF-7 cells while displaying inhibitory effects against the metastatic MDA-MB-231 cells. The findings presented here, which demonstrate the successful association between two clinically validated drugs and the ability of the hybrid matrix to modulate cell interactions, potentially contribute to the design of peptide-polymer therapeutic systems.

Preparation and characterization of molybdenum trioxide/poly(3,4-ethylenedioxythiophene): Polystyrene sulphonate nanocomposites for electrochromic application.

Electrochromic processes are mostly characterized by colour change arising from the energy of a chemical reaction involving electron transfer. Transition metal oxides of tungsten, molybdenum, iridium, and nickel show the most intense Electrochromic colour changes and photochemical stability of about 100 cycles compared to organic electrochromes which are susceptible to photochemical degradation. The prospect of conjugated polymers (comprising of metal oxides and polymers) has opened a new dimension on improving the Electrochromic performance of the transition metal oxides. In this work, solution growth methods were employed in preparing a MoO3/PEDOT: PSS composite layer by adding PEDOT: PSS into MoO3 aqueous dispersion resulting in an electrostatic interaction between MoO3 and PEDOT: PSS for electrochromic application. This composite has shown a long-term stability up to more than 550 cycles which shows higher potential specific capacitance than WO3/PEDOT: PSS. This approach has significantly improved the stability issue of MoO3 and enhances the potential of MoO3-based materials for electrochromic applications. The semi crystalline nature of MoO3-300 °C was further proved by FE-SEM observation of the MoO3 nanoparticles. The particle size shown in the images corresponds with FE-SEM result and polycrystalline structure was observed under high magnification. The polycrystalline nature of the MoO3 particles favors their electrochemical stability, while their small size facilitates their effective interactions with PEDOT: PSS. The electrochemical properties of MoO3, PEDOT: PSS and composite were further studied by cyclic voltammetry (CV) from -1 V to +1 V. MoO3 has a broad oxidation peak at -0.43 V and no obvious reduction peak in this range. PEDOT: PSS has an oxidation peak at -0.02 V and a reduction peak at -0.55 V. In the composite, the peak at -0.43 V becomes a shoulder and a new pair of redox peaks appear at -0.18 V/-0.09 V.

The Impact of Potassium Binders on Mortality in Patients with Hyperkalemia: A Single-Center Study

Hyperkalemia is associated with an increased risk of mortality and is a common complication in patients with chronic kidney disease (CKD). Despite the prevalence of hyperkalemia, current real-world data suggest that serum potassium levels are not effectively managed in clinical practice. The potential benefit of potassium binders in reducing the risk of death has not been thoroughly investigated. Therefore, this retrospective cohort study aimed to investigate the potential impact of potassium binders on mortality risk in patients with CKD by analyzing electronic medical records. The study included 1689 patients with CKD and hyperkalemia (serum potassium level &gt; 5.0 mEq/L), who visited Kawasaki Medical School Hospital between January 2014 and December 2018. The patients were divided into two groups: those without CPS (calcium polystyrene sulphonate) treatment (CPS_OFF) and those with CPS treatment (CPS_ON). The results showed that the incidence of death was significantly higher in the CPS_OFF group than in the CPS_ON group (22.3% vs. 19.6%, p &lt; 0.001). After propensity score matching, the CPS_ON group had a higher survival rate than the CPS_OFF group (log-rank test, p = 0.020). These results suggest that potassium binders may reduce the risk of death in patients with CKD and hyperkalemia. We hope that the results of this cohort study will be confirmed in future RCTs.

Pharmacological strategies to manage hyperkalaemia: out with the old, in with the new? Not so fast….

Since the 1950s, sodium polystyrene sulphonate (SPS) has been the dominant cation exchange agent prescribed for hyperkalaemia. Clinicians have had plenty of time to learn of SPS's advantages and limitations. The demands of drug regulatory agencies regarding the incorporation of medications into the market were not so stringent then as they are today, and the efficacy and safety of SPS have been questioned. In recent years, two novel cation exchangers, patiromer and sodium zirconium cyclosilicate, have received (or are in the process of receiving) regulatory approval in multiple jurisdictions globally, after scrutiny of carefully conducted trials regarding their short-term and mid-term efficacy. In this debate, we defend the view that all three agents are likely to have similar efficacy. Harms are much better understood for SPS than for newer agents, but currently there are no data to suggest that novel agents are safer than SPS. Drug choices need to consider costs, access and numbers-needed-to-treat to prevent clinically important events; for potassium exchangers, we need trials directly examining clinically important events.

Preparation of open tubular capillary column covalently coated with polystyrene sulfonate with 4,4'-azobis (4-cyanopentanoyl chloride) as polymerization initiator for electrochromatographic separation of alkaloids, sulfonamides and peptides.

An open tubular capillary electrochromatography column covalently bonded with polystyrene sulphonate was prepared via in situ polymerization using functionalized azo-initiator 4,4'-Azobis(4-cyanopentanoyl chloride). Scanning electron, fluorescence and atomic force microscopy techniques showed the formation of a relatively rough layer of polymer. In addition, -CN and C = O stretching vibrations from infrared spectroscopy proved the successful immobilization of the azo-initiator through covalent bonding and X-rayPhotoelectronSpectroscopy confirmed the elemental composition of the formed polymer layer. The prepared column was found to be appropriate for small and medium-sized molecules separation. Compared to bare fused silica capillary column higher selectivity and resolution were obtained for the separation of alkaloids, sulfonamides and peptides as a result of the electrostatic and pi-pi stacking interactions between the small organic molecules and the coated column without compromising the electroosmotic flow mobility. Separation efficiency was also increased compared to the bare capillary for the separation of alkaloids (about 1.5 times). Moreover, intraday, inter day, intra batch and inter batch relative standard deviation values of retention time and peak area of peptides were within 2% and 10%, respectively, indicating a good repeatability of the column preparation procedure. The developed method for the covalent bonding of polymers through a functionalized azo-initiator could represent a promising stable method for the preparation of open tubular column. This article is protected by copyright. All rights reserved.

Maximising 3D printed supercapacitor capacitance through convolutional neural network guided Bayesian optimisation

ABSTRACT A convolutional neural network (CNN) guided Bayesian optimisation framework is introduced to strategically maximise the surface to volume ratio of 3D printed lattice supercapacitors. We applied Bayesian optimisation on printing parameters to exploit regions where uniform and narrow lines are printed. A line shape classifying CNN model guided the optimiser’s search space to straight-line printed regions, minimising optimisation time and cost. An automatic scoring method allowed each iteration to be conducted within two minutes with accurate and precise measurements. The optimisation process has been demonstrated with graphene oxide (GO) and poly(3,4-ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) inks. The results were compared to the parameters that follow the conventional methodologies of direct ink writing (DIW) 3D printing. For each printed line of GO and PEDOT:PSS inks, irregularities decreased by 61.8% and 18.9% and average widths decreased by 39.0% and 28.6%. PEDOT:PSS lattice supercapacitor printed using optimised result showed a 151.0% increase in specific capacitance.

Electron donor–acceptor (D-A) tuning to achieve soluble covalent organic polymers for optoelectronic devices

Covalent organic polymers (COPs) have emerged as a unique class of luminescent polymers with pre-designed quasi-ordered architectures. However, their layered stacks and limited solubility preclude further processing for large-scale applications in devices, especially optoelectronic equipment. Herein, a universal strategy to adjust the electron donor–acceptor (D-A) moieties of the building blocks in COPs is proposed, achieved by in situ charge exfoliation of COP blocks into few-layer true solutions in (Lewis) acid and base media. The electron D-A moieties of the building blocks endow the COPs with the ability to accept or donate electrons, by altering the electron cloud distribution as well as the relative energy levels of the frontier molecular orbitals. The resultant soluble COPs can easily be processed into a uniform film by solution processing via the spin-coat method. The obtained COP-N achieves efficient and stable perovskite electroluminescence as a novel hole injection material on indium tin oxide, and the operating lifetime for a perovskite quantum dot light-emitting diodes device exceeds that of a poly(ethylene dioxythiophene):polystyrene sulphonate counterpart. This straightforward electronic regulation strategy provides a new avenue for the rational synthesis of processable reticular molecular polymers for practical electronic devices.

PEDOT: PSS promotes neurogenic commitment of neural crest-derived stem cells.

Poly (3,4-ethylendioxythiophene) polystyrene sulphonate (PEDOT:PSS) is the workhorse of organic bioelectronics and is steadily gaining interest also in tissue engineering due to the opportunity to endow traditional biomaterials for scaffolds with conductive properties. Biomaterials capable of promoting neural stem cell differentiation by application of suitable electrical stimulation protocols are highly desirable in neural tissue engineering. In this study, we evaluated the adhesion, proliferation, maintenance of neural crest stemness markers and neurogenic commitment of neural crest-derived human dental pulp stem cells (hDPSCs) cultured on PEDOT:PSS nanostructured thin films deposited either by spin coating (SC-PEDOT) or by electropolymerization (ED-PEDOT). In addition, we evaluated the immunomodulatory properties of hDPSCs on PEDOT:PSS by investigating the expression and maintenance of the Fas ligand (FasL). We found that both SC-PEDOT and ED-PEDOT thin films supported hDPSCs adhesion and proliferation; however, the number of cells on the ED-PEDOT after 1 week of culture was significantly higher than that on SC-PEDOT. To be noted, both PEDOT:PSS films did not affect the stemness phenotype of hDPSCs, as indicated by the maintenance of the neural crest markers Nestin and SOX10. Interestingly, neurogenic induction was clearly promoted on ED-PEDOT, as indicated by the strong expression of MAP-2 and —Tubulin-III as well as evident cytoskeletal reorganisation and appreciable morphology shift towards a neuronal-like shape. In addition, strong FasL expression was detected on both undifferentiated or undergoing neurogenic commitment hDPSCs, suggesting that ED-PEDOT supports the expression and maintenance of FasL under both expansion and differentiation conditions.

Chitosan mediated layer-by-layer assembly based graphene oxide decorated surface plasmon resonance biosensor for highly sensitive detection of β-amyloid

Alzheimer's disease (AD), and its consequent effect primarily clinical dementia, Parkinson’s disease dementia, etc. currently bring potential avenues for diagnosis centered on identification of beta-amyloid1–42 (Aβ1–42). Unfortunately, techniques engaged in AD core biomarker (Aβ1–42) detection are majorly suffering from poor sensitivity and selectivity. Thus, we fabricated graphene oxide (GO) surface decorated chitosan (CS) mediated layer-by-layer (LbL) assembly based surface plasmon resonance (SPR) biosensor for highly sensitive and selective recognition of Aβ1–42. Briefly, silver nanoparticles (AgNPs) and GO synthesis were achieved through a greener approach. LbL assembly was designed using CS and polystyrene sulphonate (PSS) on surface of AgNPs (AgNPs-CS-PSS-CS) and then antibodies of Aβ (anti-Aβ) were fixed on LbL assembly (AgNPs-CS-PSS-CS@anti-Aβ). Herein, amine functionality of CS offers a plethora of sites for anti-Aβ antibody immobilization that gives specific direction, high selectivity, and an adequate amount of antibody immobilization. For fabrication, synthesized GO was immobilized on an amine-modified gold-coated sensor chip via carbodiimide chemistry followed by AgNPs-CS-PSS-CS@anti-Aβ immobilization on an activated GO surface. Inimitable features of LbL assembly showed improved selectivity towards Aβ peptide whereas utilization of affinity biotransducer with a combination of plasmonic and non-plasmonic nanomaterial improved sensitivity and selectivity. Consequently, linearity range and limit of detection (LOD) of Aβ1–42 antigens were found to be 2 fg/mL to 400 ng/mL and 1.21 fg/mL, respectively. Moreover, analysis of Aβ1–42 in AD-induced rats confirmed the real-time-applicability of the designed SPR biosensor. Hence, GO surface decorated AgNPs-CS-PSS-CS@anti-Aβ mediated SPR biosensor would provide a novel approach for exceptionally sensitive and selective Aβ detection.

Silver-doped active carbon spheres and their application for microbial decontamination of water

Highly efficient and durable, silver nanoparticles doped Active Carbon Spheres ACS(Ag) were synthesized by carbonization and activation of silver exchanged resins. The silver exchanged resins were prepared by exchanging H+ ions of polystyrene sulphonate resin with Ag+ ions of silver nitrate (AgNO3). The quantity of Ag+ in the spheres was controlled by varying the concentration of AgNO3, from 0.0125 to 0.1 M. With increasing molar concentration of AgNO3, the effective intake of Ag+ by the sphere increases from 1.1 to 8.1 weight percent (wt %). For activation, the spheres were incubated in the CO2 atmosphere for 6 h at fixed soaking temperature i.e. 1123 K. The characterization of synthesized silver doped ACS was performed by using different sophisticated instrumental techniques. The antimicrobial activity of silver doped ACS was studied against different bacterial strains like, E. coli, B. subtilis and Staphylococcus aureus. The study demonstrated that the zone of inhibition for E. coli was 16.9 ± 0.7 mm while for B. subtilis it was 17.1 ± 0.3 mm at a concentration of 8 mg of synthesized material. In addition, satisfactory results were obtained in shake flask and filtration test experiments also, even at a low concentration of 2 mg, showing growth inhibition of 94% for E. coli and 93% for B. subtilis. When the concentration of silver doped ACS was increased to 8 mg, complete removal of both the bacteria was observed after 24 h (100 % reduction for E. coli and B. subtilis). Furthermore, when silver doped ACS was tested against Staphylococcus aureus according to ASTM:E 2149-01 method, biocidal activity of up to 73% was observed. Therefore, the silver doped ACS can be considered as a potential biocidal material for the studied bacterial strains and hence find suitable application for decontamination of water.

Viability of Activated Carbon Derived from Polystyrene Sulphonate Beads as Electrical Double Layer Capacitors

In this paper, a commercial polymeric resin precursor (polystyrene sulphonate beads) was used as a source of carbon spheres. The resin was pyrolyzed at different temperatures (700, 800, and 900 °C) and the resulting carbons were analyzed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). From the result of EIS, carbon spheres obtained at 700 °C (CS−700) have the least ohmnic resistance and highest capacitance. In furtherance, the resin was chemically activated with iron (III) chloride FeCl3·6H2O at different concentration (0.1 M, 0.3 M, and 0.5 M) and pyrolyzed at 700 °C to obtain activated carbon sphere namely (ACS 700−0.1, ACS 700−0.3, and ACS 700−0.5) in which the last digit of the samples denotes the concentration of FeCl3. Scanning electron microscope (SEM) showed that the carbon is of spherical shape; X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and X-ray photon electron spectroscopy (XPS) revealed successful introduction of Fe on the surface of the carbon. Out of all the activated carbon spheres, ACS 700−0.1 exhibited highest double layer capacitance of 9 µF cm−2 and lowest charge transfer resistance of 3.33 KΩ·cm2. This method shows that carbon spheres obtained from a polymeric source can be easily improved by simple resin modification and the carbon could be a potential candidate for an electrical double layer capacitor.

Prevalence and factors associated with hyperkalaemia in stable kidney transplant recipients.

ABSTRACTBackgroundHyperkalaemia is a frequent and potentially life-threatening condition in patients with chronic kidney disease (CKD). Even after successful kidney transplantation (KTx), KTx recipients have mild to severe CKD. Moreover, they share comorbid conditions and frequently use medications that predispose to hyperkalaemia. This study aimed to examine the prevalence and factors associated with hyperkalaemia in this population.MethodsOver a pre-specified period of 6 months (1 September 2019 to 31 March 2020), we recorded in cross-sectional fashion information on serum potassium (K+) and relevant demographics, comorbidities, medications, laboratory and transplant-associated variables in clinically stable KTx recipients attending the Transplant Outpatient Clinic of our Department. Ηyperkalaemia was classified as follows: serum K+ level >5.0 mEq/L; and further as >5.0 mEq/L with concomitant use of sodium (Na+) polystyrene sulphonate; serum K+ ≥5.2 mEq/L; serum K+ ≥5.5 mEq/L. Univariate and multiple logistic regression analyses were used to identify factors associated with serum K+ >5.0 mEq/L.ResultsThe study population consisted of 582 stable KTx recipients, 369 (63.4%) males, aged 52.4 ± 13.5 years, with estimated glomerular filtration rate (eGFR) of 55.8 ± 20.1 mL/min/1.73 m2 transplanted for >1 year. The prevalence of hyperkalaemia defined as K+ >5.0 mEq/L; >5.0 mEq/L and use of Na+ polystyrene sulphonate; K+ ≥5.2; or K+ ≥5.5 mEq/L, was: 22.7, 22.7, 14.4 and 4.1% (132, 132, 84 and 24 patients), respectively. In multivariate analysis, male gender [odds ratio (OR) = 2.020, 95% confidence interval (CI) 1.264–3.227] and use of renin–angiotensin–aldosterone system (RAAS) blockers (OR = 1.628, 95% CI 1.045–2.536) were independently associated with hyperkalaemia, while higher eGFR (OR = 0.967, 95% CI 0.955–0.979) and use of non-K+-sparing diuretics (OR = 0.140, 95% CI 0.046–0.430) were associated with lower odds of the disorder.ConclusionsThe prevalence of mild hyperkalaemia in stable KTx recipients is relatively high but that of moderate or severe hyperkalaemia is low. Among a wide range of factors studied, only male gender and RAAS blockade were associated with increased odds of hyperkalaemia, while higher eGFR and diuretics were associated with decreased odds of hyperkalaemia.

Characterisation of mass distributions of solvent-fractionated lignins using analytical ultracentrifugation and size exclusion chromatography methods

Lignins are valuable renewable resources for the potential production of a large array of biofuels, aromatic chemicals and biopolymers. Yet native and industrial lignins are complex, highly branched and heterogenous macromolecules, properties that have to date often undermined their use as starting materials in lignin valorisation strategies. Reliable knowledge of weight average molar mass, conformation and polydispersity of lignin starting materials can be proven to be crucial to and improve the prospects for the success of such strategies. Here we evaluated the use of commonly-used size exclusion chromatography (SEC)—calibrated with polystyrene sulphonate standards—and under-used analytical ultracentrifugation—which does not require calibration—to characterise a series of lignin fractions sequentially extracted from soda and Kraft alkaline lignins using ethyl acetate, methyl ethyl ketone (MEK), methanol and acetone:water (fractions F01–F04, respectively). Absolute values of weight average molar mass (Mw) determined using sedimentation equilibrium in the analytical ultracentrifuge of (3.0 ± 0.1) kDa and (4.2 ± 0.2) kDa for soda and Kraft lignins respectively, agreed closely with previous SEC-determined Mws and reasonably with the size exclusion chromatography measurements employed here, confirming the appropriateness of the standards (with the possible exceptions of fraction F05 for soda P1000 and F03 for Indulin). Both methods revealed the presence of low (~ 1 kDa) Mw material in F01 and F02 fractions followed by progressively higher Mw in subsequent fractions. Compositional analysis confirmed > 90% (by weight) total lignins successively extracted from both lignins using MEK, methanol and acetone:water (F02 to F04). Considerable heterogeneity of both unfractionated and fractionated lignins was revealed through determinations of both sedimentation coefficient distributions and polydispersity indices. The study also demonstrates the advantages of using analytical ultracentrifugation, both alongside SEC as well as in its own right, for determining absolute Mw, heterogeneity and conformation information for characterising industrial lignins.

Scalable synthesis of monodisperse and recyclable sulphonated polystyrene microspheres for sustainable elimination of heavy metals in wastewater

ABSTRACT Herein, we demonstrate a scalable method for fabricating monodisperse sulphonated polystyrene (SPS) microspheres with abundant sulphonic acid groups and excellent heavy metal removal ability. A comprehensive characterization through SEM, EDS, FT-IR, TG, XRD and XPS confirmed the formation of the SPS microspheres. Take advantage of the abundant sulphonic acid groups on the surface of microspheres, as well as the superior monodisperse properties, adsorption ability of SPS microspheres both in quantity and speed have been enhanced. The adsorption equilibrium obeyed the Langmuir isotherm model with the theoretical maximum capacities of 49.16, 15.38 and 13.89 mg·g−1 for Pb2+, Zn2+ and Cu2+, respectively (30°C, pH = 3.5). Besides, the adsorption equilibriums of Pb2+ onto SPS microspheres can be achieved within only 1 min and the adsorption kinetics can be fitted by a pseudo-second-order kinetics model. More importantly, because of the micron structure of the SPS microspheres, it could overcome the excessive hydrophilia brought by rich sulphonic acid groups and thereby easily separated, which maintain a good recyclable capacity after five regeneration cycles. With the excellent adsorption ability and reusability, SPS microspheres can efficiently handle the polluted water in a convenience and rapid process, which satisfies the sustainable pollution treatment in heavy metals elimination.

Prise en charge de l’hyperkaliémie récidivante et utilisation des inhibiteurs du système rénine-angiotensine-aldostérone : analyse des données françaises de l’étude multinationale européenne PROKALE

IntroductionRecurrent hyperkalaemia may result in underutilisation of renin-angiotensin-aldosterone system inhibitors. We report an analysis of French data from the PROKALE retrospective study, which assessed the management of recurrent hyperkalaemia in five European countries. Patients and methodsA retrospective chart review including patients not on dialysis with two or more hyperkalaemia episodes≥5.5 mEq/L documented within a 12-month observation period was performed. ResultsIn France, 115 physicians (57 nephrologists et 58 cardiologists) participated in the study and 295 patients were studied in this analysis. Mean age was 68 years; 212 patients (71.9%) had chronic kidney disease, 108 (36.6%) had chronic heart failure and 102 (34.6%) had diabetes mellitus. The mean number of documented hyperkalaemic episodes was 2.3. A total of 90 hospitalizations occurred during the observation period, of which 24 (26.7%) were directly related to a hyperkalaemic episode. At the time of the first documented hyperkalaemic episode, measures used for the management of hyperkalaemia included loop diuretics (144 patients [48.8%]), sodium/calcium polystyrene sulphonate (135 patients [45.8%]), a low-potassium diet (31 patients [10.5%]) and sodium bicarbonate (31 patients [10.5%]). Between the two consecutive hyperkalaemic episodes documented, the proportion of patients on renin-angiotensin-aldosterone system inhibitors treatment decreased from 42.4% to 34.6%. ConclusionRenin-angiotensin-aldosterone system inhibitors treatment interruptions were observed in the setting of recurrent hyperkalaemic episodes. Recurrent hyperkalaemia is a major cause of hospitalizations. More effective strategies for the prevention of recurrent hyperkalaemia are needed.