Molecular Weight Cut-off Values Research Articles

Conformationally tunable calix[4]pyrrole-based nanofilms for efficient molecular separation

Preparation of nanofilms which are able to reject water-soluble low molecular weight organic compounds in nanofiltration remains to be a challenge. Herein, we report a new kind of self-standing, defect-free, robust, centimeter-sized and thickness controllable calix[4]pyrrole (C[4]P)-based nanofilms with excellent molecular sieving performance in nanofiltration. The nanofilms were prepared via confined dynamic condensation of the tetra-benzoyl-hydrazine derivative of calix[4]pyrrole (CPTBH) with 1,3,5-benzenetricarboxaldehyde (BTC) at the air/dimethyl sulfoxide (DMSO) interface. Nanofiltration tests under 2 bar pressure with porous polyethylene terephthalate (PET) as the support and a CsF treated CPTBH-BTC nanofilm (∼100 nm) as the selective layer depicted a water permeance of 15 L m-2h−1 bar−1 and a methanol permeance of 45 L m-2h−1 bar−1. High rejection rates (>95%) were found in aqueous solution for most of the tested dyes and pharmaceuticals. Remarkably, the composite membrane also demonstrated good separation performance in aqueous phase to some amino acids and organic dyes with molecular weights around 200 g/mol. High-performance nanofiltration in methanol was also realized. In this case, the molecular weight cutoff value is ∼ 800 g/mol. These findings showed that introduction of macrocyclic hosts is an effective way to develop nanofilms with high solvent permeance but low molecular weight cutoff value.

SEPARATION OF HEMICELLULOSES FROM AN INDUSTRIAL STREAM BY NANOFILTRATION AND ULTRAFILTRATION PROCESSES

The performance of nanofiltration (NF) and ultrafiltration (UF) membranes was studied for separating hemicelluloses from a highly alkaline industrial stream, containing 17-18 wt% sodium hydroxide, resulting from the viscose process. Initially, screening experiments were performed to select suitable membranes, which were then investigated on a pilot scale spiral module. Screening experiments showed that the UF membrane, with a nominal molecular weight cut-off (MWCO) value of 3 kDa, and the NF one, with a nominal MWCO value of 0.5 kDa, showed a similar range of filtration performance and a flux of 4.2 L/m2.h. Further, a retention efficiency of 50% was observed for the 5 kDa and the 10 kDa membranes, indicating absence of any significant proportion of hemicelluloses in this range of molecular weights. The effects of process conditions were studied to understand their correlation with membrane performance with respect to hemicelluloses retention and permeate flux. UF membranes were found to be more prone to performance deterioration over time and with the number of cycles of usage during the pilot scale study, whereas the NF membrane showed consistent performance. It was seen that feed dilution can improve the membrane performance with respect to sodium hydroxide recovery. Significant reduction in feed viscosity with dilution resulted in a 50% increase in flux after normalizing for concentration.

Diversity matters: Widening the chemical space in organic solvent nanofiltration

Niche membrane technologies, such as organic solvent nanofiltration (OSN), offer considerable energy and operation cost reduction compared with conventional separation methods. However, despite their many advantages, their industrial implementation is hindered by small and specialized datasets, which hinders the development of more advanced prediction methods. In this study, we developed a medium-throughput system (MTS) for OSN with high robustness and low error. The MTS was used to generate a dataset containing 336 different molecules, and their rejection values were measured at two different pressures using three commercial DuraMem polyimide membranes with different molecular weight cut-off values in methanol. The diversity of the generated dataset was compared with the diversity values of other relevant datasets using 26 different chemometric molecular descriptors, including the heteroatom count, topological surface area, different shape descriptors, Van der Waals volume, logP, and logS. The rejection was found to be weakly dependent on the functional group and molecular weight at the lower end of the nanofiltration range. We proposed the use of a novel structural similarity-based indexing method for comparing solutes. Also, we established the first open-access and searchable dataset for OSN rejection values. The newly established www.osndatabase.com pilot website acts as the foundation of the dataset.

Orange juice ultrafiltration: characterisation of deposit layers and membrane surfaces after fouling and cleaning

Abstract The influence of feed condition and membrane cleaning during the ultrafiltration (UF) of orange juice for phytosterol separation was investigated. UF was performed using regenerated cellulose acetate (RCA) membranes at different molecular weight cut-off (MWCO) values with a 336 cm2 membrane area and a range of temperatures (10–40 °C) and different feed volumes (3–9 L). Fluid dynamic gauging (FDG) was applied to assess the fouling and cleaning behaviours of RCA membranes fouled by orange juice and cleaned using P3-Ultrasil 11 over two complete cycles. During the FDG testing, fouling layers were removed by fluid shear stress caused by suction flow. The cleanability was characterised by using ImageJ software analysis. A Liebermann-Buchard-based method was used to quantify the phytosterol content. The results show that RCA 10 kDa filters exhibited the best separation of phytosterols from protein in orange juice at 20 °C using 3 L feed with a selectivity factor of 17. Membranes that were fouled after two cycles showed higher surface coverage compared to one fouling cycle. The surface coverage decreased with increasing fluid shear stress from 0 to 3.9 Pa. FDG achieved 80–95% removal at 3.9 Pa for all RCA membranes. Chemical cleaning using P3-Ultrasil 11 altered both the membrane surface hydrophobicity and roughness. These results show that the fouling layer on RCA membranes can be removed by fluid shear stress without affecting the membrane surface modification caused by chemical cleaning.

Danimer Scientific enters agreement to acquire Novomer for $152 M

The study compared five NF membranes with varied water contact angles and molecular weight cut-off (MWCO) values for their effectiveness to remove dissolved organic carbon (DOC) and inorganic ions from micro-filtered water obtained from a wastewater-reclamation plant. The NF 90 membrane with the highest contact angle (790, least hydrophilic) and one with the lowest MWCO value ((90–200 Da) was the most efficient in removing DOC (88% rejection compared to 37–84% for the others) and inorganics (75% electrical conductivity rejection compared to 9–27% for the others). Of the 10 organic micropollutants in the feed water, >90% of 7 were removed.

Waltzing around the stereochemistry of membrane crosslinkers for precise molecular sieving in organic solvents

Crosslinking of polymeric membranes induces changes in both membrane stability and separation performance. Numerous membrane-crosslinking methods have been developed with the objective of obtaining improved membranes. However, none of these methods systemically investigated the stereochemical effects of the crosslinker in the pursuit of better stability and performance. Herein, we address this knowledge gap by presenting a systematic investigation of the stereochemistry of crosslinkers. The intrinsically microporous poly(ether-ether-ketone)-containing Tröger's base (iPEEK-TB) was synthesized and employed in the fabrication of organic solvent nanofiltration (OSN) membranes. Crosslinkers were carefully selected based on the stereochemical position of the two benzyl bromide functional groups, separated by distances of 4.3, 8.2, 8.5, and 12.4 Å and significant effects arising from crosslinking on membrane physical properties, morphology, and OSN performance were investigated. Crosslinked membranes showed excellent solvent resistance, mechanical flexibility, and thermal stability. As a function of crosslinking distance, the molecular weight cutoff (MWCO) values of the membranes varied in the range of 575–750 g mol−1. The para isomer of the crosslinkers resulted in higher permeance relative to membranes crosslinked with their counterpart ortho isomers, and vice versa, the ortho substitution resulted in higher solute rejection values compared with para isomers. An increase of 50% and 12% in acetonitrile permeance relative to the annealed benchmark membrane was observed upon the treatment using iPEEK-TB with 4,4′-bis(bromomethyl)biphenyl (p-BBMBP) and 2,2′-bis(bromomethyl)-1,1′-biphenyl (o-BBMBP), respectively, whereas a permeance decrease of approximately 23% and 32% was noted upon treatment with α,α′-Dibromo-p-xylene (p-DBX) and α,α′-Dibromo-o-xylene (o-DBX), respectively. The corresponding MWCO changes were found to decrease for all crosslinked membranes within the range of 12%–40%. The crosslinked membranes demonstrated stable performance in polar aprotic solvents such as N,N-dimethylformamide and N-methyl-2-pyrrolidone. The Molecular dynamic (MD) simulations supported the obtained performance results through the variations in the fractional free volume (FFV). This work demonstrates the importance of crosslinker selection for OSN membrane performance and solvent resistivity and opens new avenues for fine-tuning membrane stability and OSN performance.

Fabrication and performance evaluation of polymeric membrane using blood compatible hydroxyapatite for artificial kidney application.

In the current study, a phase inversion scheme was employed to fabricate hydroxyapatite (HA)/polysulfone (PSF)-based asymmetric membranes using a film applicator with water as a solvent and nonsolvent exchanging medium. Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) spectroscopic studies were conducted to confirm the bonding chemistry and purity of filler. The inherent thick nature of PSF generated sponge-like shape while the instantaneous demixing process produced finger-like pore networks in HA/PSF-based asymmetric membranes as exhibited by scanning electron microscope (SEM) micrographs. The FTIR spectra confirmed noncovalent weak attractions toward the polymer surface. The leaching ratio was evaluated to observe the dispersion behavior of HA filler in membrane composition. Hydrophilicity, pore profile, pure water permeation (PWP) flux, and molecular weight cutoff (MWCO) values of all formulated membranes were also calculated. Antifouling results revealed that HA modified PSF membranes exhibited 43% less adhesion of bovine serum albumin (BSA) together with >86% recovery of flux. Membrane composition showed 74% total resistance, out of which 60% was reversible resistance. Biocompatibility evaluation revealed that the modified membranes exhibited prothrombin time (PT), and thrombin time (TT) comparable with typical blood plasma, whereas proliferation of living cells over membrane surface proved its nontoxic behavior toward biomedical application. The urea and creatinine showed effective adsorption aptitude toward HA loaded PSF membranes.

Enhancing the Separation Performance of Aqueous Phase Separation-Based Membranes through Polyelectrolyte Multilayer Coatings and Interfacial Polymerization.

The aqueous phase separation (APS) technique allows membrane fabrication without use of unsustainable organic solvents, while at the same time, it provides extensive control over membrane pore size and morphology. Herein, we investigate if polyelectrolyte complexation-induced APS ultrafiltration membranes can be the basis for different types of nanofiltration membranes. We demonstrate that APS membranes can be used as support membranes for functional surface coatings like thin polyelectrolyte multilayer (PEMs) and interfacial polymerization (IP) coatings. Three different PEMs were fabricated on poly(sodium 4-styrene sulfonate) (PSS) poly(allylamine hydrochloride) (PAH) APS ultrafiltration membranes, and only 4.5 bilayers were needed to create nanofiltration membranes with molecular weight cut-off (MWCO) values of 210–390 Da while maintaining a roughly constant water permeability (∼1.7 L·m–2·h–1·bar–1). The PEM-coated membranes showed excellent MgCl2 (∼98%), NaCl (∼70%), and organic micropollutant retention values (>90%). Similarly, fabricating thin polyamide layers on the ultrafiltration PSS-PAH APS membranes by IP resulted in nanofiltration membranes with MWCO values of ∼200 Da. This work shows for the first time that APS membranes can indeed be utilized as excellent support membranes for the application of functional coatings without requiring any form of pretreatment.

The kidney of the Nodularia freshwater mussel has a larger filtration-size and counter-current system with improved water excretion compared with the seawater mussel Mytilus.

ABSTRACTHistological studies and magnetic resonance imaging were employed to analyze the kidney structure and function of the freshwater mussel, Nodularia douglasiae. The Nodularia kidney consists of proximal, intermediate and distal tubules. The epithelia of the renal tubules were composed of a single layer of cuboidal cells. The proximal and distal tubules run in opposite directions underneath the pericardial cavity. Molecular weight cut-off (MWCO) values for the kidney filtration were detected by MR tracer injections: gadolinium-diethylenetriaminepentaacetic acid (GdDTPA) at 0.55 kDa, an oligomer-based contrast agent (CH3-DTPA-Gd) at 2.2 kDa, as well as Gd-DTPA-polylysine at 10, 22, and 110 kDa. The T1w-MRI intensity and T1 relaxation rate (R1) of the pericardial cavity and renal tubules increased with tracers smaller than 10 kDa. The other tracers showed only minimal or no increase. Thus, we concluded that the MWCO of the kidney is 22 kDa, 50 times larger than that for the Mytilus living in seawater. Since the R1 values of the renal tubules were similar to those of the pericardial cavity, the kidney did not concentrate filtrated tracers. The slow decay of the magnetic resonance (MR) tracers from the renal tubules indicated a low filtration rate, suggesting that the counter-current system reabsorbs useful solutes without reabsorption of water. The higher MWCO may be beneficial to maintain the tubular oncotic pressure and allow excretion of excess water. In conclusion, a main renal function of the freshwater mussel is the excretion of water, opposite to that of the seawater mussel and vertebrates, which preserve water.

MECHANICAL PROPERTIES OF POLYSULFONE-ZnO NANOCOMPOSITE MEMBRANE

Large quantities of wastewater are generated by the petroleum refining process. Micron-scale emulsion droplets and submicron droplets are difficult to remove from oil-refined wastewater, and addressing these issues has been a major challenge for researchers. Membrane technology is widely used in water treatment because it is very selective and effective in the filtration process. his research focuses on oil refinery water treatment using a polysulfone membrane (PSF)-nano-ZnO membrane with the addition of polyethylene glycol (PEG). This research aims to determine the PEG ratio that produces the optimum PSF-ZnO membrane in terms of mechanical properties, including thickness, tensile strength, and molecular weight cut-off (MWCO) value. The membranes with the optimum clearance were obtained at 3% PEG with a thickness of 0.0077 mm, Young's modulus of 8800 N/m2, and Morphological analysis was performed using the SEM (Scanning Electron Microscopy) method on the membrane which had the highest and lowest permeability values.. The best membrane MWCO value was achieved by the addition of 19% PSF-nano-ZnO 1% wt at 5 minutes of UV irradiation. This shows that the addition of PEG composite affects pore openings. The membrane formed with variations in PEG concentrations affecting the thickness of the membrane. Higher concentrations make the membrane thicker, resulting in a higher Young’s modulus.

Silver-polyamidoamine/graphene oxide thin film nanofiltration membrane with improved antifouling and antibacterial properties for water purification and desalination

Graphene oxide (GO), silver (Ag), and polyamidoamine (PAMAM) have individually proven effective at enhancing the properties of thin-film nanocomposite (TFN) membranes. Here, we report their synergic efficacy for water purification and desalination purposes. We fabricate TFN membranes filled with Ag-PAMAM-decorated graphene oxide (GO@PAMAM@Ag) and characterize their surface hydrophilicity, water permeability, salt and dye retentions, and antibacterial and antifouling capacities. We show that TFNs filled with 0.02 wt% GO@PAMAM@Ag have a contact angle of ~26°, down from ~53° in the pristine form, exhibiting strong antifouling properties. Molecular weight cut-off values of the membranes indicate that the filler considerably reduces the pore size of the membranes. We show that the filler improves the rejection capacity of TFN membranes against Na2SO4 and Cr(NO3)3 and imparts to the membranes excellent dye retention (>99% for Viola Crystallina) and inhibitory effects against two main causative agents of bloodstream infections, Escherichia coli and Staphylococcus aureus. Overall, GO@PAMAM@Ag-filled TFN membranes exhibit quality performance across several indicators showing great promise for use in water treatment facilities.

Polydopamine-Assisted Two-Dimensional Molybdenum Disulfide (MoS2)-Modified PES Tight Ultrafiltration Mixed-Matrix Membranes: Enhanced Dye Separation Performance.

Tight ultrafiltration (TUF) membranes with high performance have attracted more and more attention in the separation of organic molecules. To improve membrane performance, some methods such as interface polymerization have been applied. However, these approaches have complex operation procedures. In this study, a polydopamine (PDA) modified MoS2 (MoS2@PDA) blending polyethersulfone (PES) membrane with smaller pore size and excellent selectivity was fabricated by a simple phase inversion method. The molecular weight cut-off (MWCO) of as-prepared MoS2@PDA mixed matrix membranes (MMMs) changes, and the effective separation of dye molecules in MoS2@PDA MMMs with different concentrations were obtained. The addition amount of MoS2@PDA increased from 0 to 4.5 wt %, resulting in a series of membranes with the MWCO values of 7402.29, 7007.89, 5803.58, 5589.50, 6632.77, and 6664.55 Da. The MWCO of the membrane M3 (3.0 wt %) was the lowest, the pore size was defined as 2.62 nm, and the pure water flux was 42.0 L m−2 h−1 bar−1. The rejection of Chromotrope 2B (C2B), Reactive Blue 4 (RB4), and Janus Green B (JGB) in aqueous solution with different concentrations of dyes was better than that of unmodified membrane. The separation effect of M3 and M0 on JGB at different pH values was also investigated. The rejection rate of M3 to JGB was higher than M0 at different pH ranges from 3 to 11. The rejection of M3 was 98.17–99.88%. When pH was 11, the rejection of membranes decreased with the extension of separation time. Specifically, at 180 min, the rejection of M0 and M3 dropped to 77.59% and 88.61%, respectively. In addition, the membrane had a very low retention of salt ions, Nacl 1.58%, Na2SO4 10.52%, MgSO4 4.64%, and MgCl2 1.55%, reflecting the potential for separating salts and dyes of MoS2@PDA/PES MMMs.

Comparing nanofiltration membranes effectiveness for inorganic and organic compounds removal from a wastewater-reclamation plant’s micro-filtered water

The study compared five NF membranes with varied water contact angles and molecular weight cut-off (MWCO) values for their effectiveness to remove dissolved organic carbon (DOC) and inorganic ions from micro-filtered water obtained from a wastewater-reclamation plant. The NF 90 membrane with the highest contact angle (790, least hydrophilic) and one with the lowest MWCO value ((90–200 Da) was the most efficient in removing DOC (88% rejection compared to 37–84% for the others) and inorganics (75% electrical conductivity rejection compared to 9–27% for the others). Of the 10 organic micropollutants in the feed water, >90% of 7 were removed.

Robust and Large-Area Calix[4]pyrrole-Based Nanofilms Enabled by Air/DMSO Interfacial Self-Assembly-Confined Synthesis.

The modular construction of defect-free nanofilms with a large area remains a challenge. Herein, we present a scalable strategy for the preparation of calix[4]pyrrole (C[4]P)-based nanofilms through acryl hydrazone reaction conducted in a tetrahydrazide calix[4]pyrrole (CPTH)-based self-assembled layer at the air/DMSO interface. With this strategy, robust, regenerable, and defect-free nanofilms with an exceptionally large area (∼750 cm2) were constructed. The thickness and permeability of the film systems can be fine-tuned by varying the precursor concentration or by changing another building block. A typical nanofilm (C[4]P-TFB, ∼67 nm) depicted high water flux (39.9 L m-2 h-1 under 1 M Na2SO4), narrow molecular weight cut-off value (∼200 Da), and promising antifouling properties in the forward osmosis (FO) process. In addition, the nanofilms are stable over a wide pH range and tolerable to different organic solvents. Interestingly, the introduction of C[4]P endowed the nanofilms with both outstanding mechanical properties and unique group-selective separation capability, laying the foundation for wastewater treatment and pharmaceutical concentration.

Fouling Analysis and the Recovery of Phytosterols from Orange Juice Using Regenerated Cellulose Ultrafiltration Membranes

This study describes the use of regenerated cellulose (RCA) membranes with molecular weight cut-off (MWCO) values of 10, 30, and 100 kDa, respectively, to separate phytosterols from orange juice for possible nutraceutical production. A desirable membrane separation rejects protein whilst transmitting phytosterols and other low molecular mass compounds such as sugars. The ultrafiltration was performed in a cross-flow membrane system with a total filtration area of 336 cm2. Total phytosterol analysis was carried out by using a Liebermann-Buchard-based method. Protein concentration was quantified by the Bradford method. The effects of three different membranes upon the rejection of total phytosterol content, proteins, sugar, and antioxidant activity were studied. Of the membranes tested, the 10-kDa membrane displayed the highest concentration of phytosterols in the permeate. The 30-kDa and 100-kDa membranes gave comparatively higher phytosterol rejection. The membrane surface roughness and corresponding pure water flux values varied as a function of MWCO such that RCA30 > RCA100 > RCA10. Membranes with rougher surfaces displayed higher fouling than those with smoother surfaces. Hydrophobicity and surface roughness both influenced filtration performance, by controlling the development of the protein-based foulant which modified membrane selectivity.

Biologically Active Compounds from Goji (Lycium Barbarum L.) Leaves Aqueous Extracts: Purification and Concentration by Membrane Processes.

Goji (Lycium barbarum L.) leaves and fruits have been described as a valuable source of bioactive compounds with a great potential for the development of health-promoting formulations. The present study aimed to evaluate the potential of a sustainable process for the recovery of phenolic compounds from Goji leaves through a combination of aqueous extraction and membrane-based operations. Water was used as a safe, cheap, and non-hazardous extraction solvent, and parameters of extraction of dried Goji leaves were optimized in order to maximize the yield of polyphenols, total soluble solids (TSS), and total antioxidants simultaneously. The aqueous extract was clarified by ultrafiltration and then processed with three flat-sheet polyethersulphone (PES) membranes with molecular weight cut-off (MWCO) values in the range of 0.3–4.0 kDa, in order to remove sugar compounds from polyphenols and improve the antioxidant activity of the produced fractions. Among the selected membranes, a 1 kDa membrane exhibited the best performance in terms of purification of polyphenols from the clarified aqueous extract. The rejection by this membrane of TSS and total carbohydrates was in the range of 15.8–25.3%, and was decreased by increasing the volume reduction factor (VRF). On the other hand, the retention values for total polyphenols and total antioxidant activity (TAA) were in the range of 73–80%, and were increased by increasing the VRF.

P1108FLUID DYNAMIC ASSESSMENT OF THERANOVA DIALYZER THROUGH CT IMAGING TECHNIQUE

Abstract Background and Aims Inadequate removal of molecules between 5and50KDa, due to their restriction in diffusibility, may cause long-term complication in chronic hemodialysis patients. Medium Cut-off(MCO) is a new class of membranes with enhanced sieving properties and negligible albumin loss, thanks to its high molecular weight(MW) retention onset and MW cut-off value lower than albumin MW. MCO membrane used in HD allows to perform expanded hemodialysis (HDx), a technique based on high internal filtration(IF). Our previous study quantified the IF of Theranova dialyzer leveraging a nuclear imaging technique. In order to characterize the local distribution of the IF, an in vitro study assessing the fluid dynamics inside Theranova dialyzer was conducted through CT imaging technique. Method Dialyzers Theranova 400 and 500(Baxter, Deerfield, USA) were placed in vertical position in the CT gantry. Blood and dialysate were circulated in countercurrent at 300ml/min and 500 ml/min, respectively. The two compartments were analyzed separately, injecting the dye solution, for both filters. Longitudinal sections, 0.5cm thick, were recorded for 60seconds. Results In blood compartment, dye solution immediately after its entrance in the dialyzer demonstrates homogeneous progression, while different velocity profiles were observed among the fibers proceeding to the outlet port (Fig b). In dialysate compartment, dye solution is distributed in the periphery first (Fig d), then seeps in the fibers bundle and reaches the complete compartment filling. Conclusion The homogeneous dye profile immediately after its entrance in blood compartment demonstrated a good design of the inlet port; the optimal dye distribution reached in both blood and dialysate compartments ensure that IF phenomenon is equally achieved in both central and peripheral regions of the dialyzer.

GWF-NH2 enhanced OSN membrane with trifluoromethyl groups in polyamide layer for rapid methanol recycling

Textile dyeing industry (TDI) produced huge amount of methanol effluent. An organic solvent nanofiltration (OSN) membrane owns ultra-high methanol permeance was developed in this study with a highly reactive and chemically stable symmetrical dianiline structure into its active layer. The so-called “BHTTM” molecule owns double trifluoromethyl (CF3) which offers polarity and negative charge while the matrix was doped with positively charged processed glass wool fiber (GWF-NH2) to form a specific active layer/area. FT-IR and EDX results demonstrated the successful introduction of BHTTM and their specific morphology were captured by FE-SEM. The membrane offered molecular weight cut-off value of 441.9 in water but smaller in organic solvents. It displayed outstanding OSN performance in which the methanol permeance reached 117.2 ± 9.8 L m−2 h−1 MPa−1 with 99.5 ± 0.1% rejection of Chlorazol black and methanol effluent with Rose bengal was also totally decolorized (99.5 ± 0.2%).

Novel Peptidomic Approach for Identification of Low and High Molecular Weight Tauopathy Peptides Following Calpain Digestion, and Primary Culture Neurotoxic Challenges.

Tauopathy is a class of a neurodegenerative disorder linked with tau hyperphosphorylation, proteolysis, and aggregation. Tau can be subjected to proteolysis upon calpain activation in Alzheimer disease (AD), and traumatic brain injury (TBI). We and others have extensively researched calpain-mediated tau breakdown products (Tau-BDP; 45K, 35K, and 17K). Tau proteolysis might also generate low molecular weight (LMW ≤10K) proteolytic peptides after neurodegenerative damage. In this study, we have subjected purified tau protein (phospho and non-phospho) and mouse brain lysate to calpain-1 digestion to characterize the LMW generated by nano-liquid chromatography coupled to electrospray ionization to tandem mass spectrometry (nano-LC-ESI-MS/MS). We have also challenged differentiated primary cerebrocortical neuronal cultures (CTX) with neurotoxic agents (calcium ionophore calcimycin (A23187), staurosporine (STS), N-methyl-D-aspartate (NMDA), and Maitotoxin (MTX)) that mimic neurodegeneration to investigate the peptidome released into the conditioned cell media. We used a simple workflow in which we fractionate LMW calpain-mediated tau peptides by ultrafiltration (molecular weight cut-off value (MWCO) of 10K) and subject filtrate fractions to nano-LC-MS/MS analysis. The high molecular weight (HMW) peptides and intact proteins retained on the filter were analyzed separately by western blotting using total and phospho-specific tau antibodies. We have identified several novel proteolytic tau peptides (phosphorylated and non-phosphorylated) that are only present in samples treated with calpain or cell-based calpain activation model (particularly N- and C-terminal peptides). Our findings can help in developing future research strategies emphasizing on the suppression of tau proteolysis as a target.

Novel designed TFC membrane based on host-guest interaction for organic solvent nanofiltration (OSN)

Active layers with outstanding organic solvent nanofiltration (OSN) performances were designed novelly by adopting host-guest (HG) interaction to realize adamantane structure immobilization. During the fabrication process, β-cyclodextrin (β-CD) served as the “host” while adamantylamine/adamantanemethylamine (AMA/AMmA) worked as the “guest”. Stechiometrical experiment results demonstrated that one half molar ratio of the “guest” to the “host” molecular (1.0%, w/v) led to the best OSN performance. The successful immobilization of adamantane structure was verified by XPS, FT-IR and EDX results, and the adamantane immobilized membrane showed weakened “nodule-like” pattern and reduced surface roughness values compared with the control membrane. Acetone, for the first time, was proposed as the activation solvent for enhancement of OSN performance. After acetone activation, the morphology and topography of the adamantane immobilized membranes seldom changed but their pure methanol (MeOH) flux were quintupled (29.0 ± 2.6 L m−2 h−1) and the rose bengal (RB) removed from MeOH reached to 98.2 ± 0.1%. Those HG complexes also resulted in the reduction of molecular weight cut-off (MWCO) values from 466.6 Da to 436.9 and 428.4 Da of PCA101/2+ and PCAm101/2+, respectively. Besides, the PCAm101/2+ demonstrated excellent OSN performances in the long-term operation of active pharmaceutical ingredients (APIs) concentration of clarithromycin (CLA)/acetone.