Biomaterial engineering strategies for modeling the Bruch's membrane in age-related macular degeneration

Age-related macular degeneration,a multifactorial inflammatory degenerative retinal disease,ranks as the leading cause of blindness in the elderly.Strikingly,there is a scarcity of curative therapies,especially for the atrophic advanced form of age-related macular degeneration,likely due to the lack of models able to fully recapitulate the native structure of the outer blood retinal barrier,the prime to rget tissue of age-related macular degeneration.Standard in vitro systems rely on 2D monocultures unable to adequately reproduce the structure and function of the outer blood retinal barrier,integrated by the dynamic interaction of the retinal pigment epithelium,the Bruch's membrane,and the underlying choriocapillaris.The Bruch's membrane provides structu ral and mechanical support and regulates the molecular trafficking in the outer blood retinal barrier,and therefo re adequate Bruch's membrane-mimics are key for the development of physiologically relevant models of the outer blood retinal barrie r.In the last years,advances in the field of biomaterial engineering have provided novel approaches to mimic the Bruch's membrane from a variety of materials.This review provides a discussion of the integrated properties and function of outer blood retinal barrier components in healt hy and age-related macular degeneration status to understand the requirements to adequately fabricate Bruch's membrane biomimetic systems.Then,we discuss novel materials and techniques to fabricate Bruch's membrane-like scaffolds for age-related macular degeneration in vitro modeling,discussing their advantages and challenges with a special focus on the potential of Bruch's membrane-like mimics based on decellularized tissue.

A Novel and Functional Artificial Bruch’s Membrane Made of Poly (ε-Caprolactone)/Gelatin for Retinal Pigment Epithelium Restoration

Purpose: The primary aim of this paper is to design, create, and improve functional and artificial Bruch’s membranes (BM) using bioengineering techniques, which can be applied in the treatment of maculopathies by supporting the growth and maintenance of retinal pigment epithelium (RPE) cells, thereby potentially enabling subretinal implantation in patients. Methods: We fabricated by electrospinning ultrathin 3D nanofibrous membranes from Polycaprolactone (PCL), and different concentrations of gelatin (5%, 15% and 30%). ARPE-19 cells were seeded onto these artificial membranes. MTT assays were performed in order to evaluate ARPE-19 cell viability and cytotoxicity. IF assays were realized to observe the ARPE-19 cells onto each membrane. Ultrastructure of the modified Bruch’s membrane and ARPE-19 morphology after 25 days of culture were studied with transmission and scanning electron microscopy. To evaluate expression changes in markers of ARPE-19 (RPE65 and ZO-1) qRT-PCR assays were realized. Data from three independent experiments were pooled and expressed as the mean SD. A confidence level of P 0.05 was considered to be statistically significant. Results ARPE-19 cells grew on PCL/Gelatin membranes mainly in PCL/30% gelatin combination, which had not cytotoxic effect. RPE65/cytokeratin-18/ and actin-positive ARPE-19 cells formed a correctly orientated monolayer of polygonal cells with morphological polarity. The apical cell surfaces exhibited abundant protruding microfolds. Moreover, zones of polygonal border look as if ARPE-19 cells fused among, suggesting the presence of tight junctions. The expression of RPE65 and ZO-1 was unchanged. Conclusions: PCL/30% Gelatine membranes may imitate the natural BM to such extent that they support RPE-cells and exhibited RPE-like morphology. The engineering of a human RPE monolayer with these artificial BM, emulating the in vivo retina, arouse their potential subretinal implantation in patients with wet age-related macular degeneration (AMD) where there is a rupture of the Bruch’s membrane.

Milk fat globule membrane supplementation protects againstβ-lactoglobul-ininduced food allergy in mice via upregulation of regulatory T cells and enhancement of intestinal barrier in a microbiota-derived short-chain fatty acids manner

Milk fat globule membrane(MFGM),which contains abundant glycoproteins and phospholipids,exerts beneficial effects on intestinal health and immunomodulation.The aim of this study was to evaluate the protective effects and possible underlying mechanisms of MFGM on cow’s milk allergy(CMA)in aβ-lactoglobulin(BLG)-induced allergic mice model.MFGM was supplemented to allergic mice induced by BLG at a dose of 400 mg/kg body weight.Results demonstrated that MFGM alleviated food allergy symptoms,decreased serum levels of lipopolysaccharide,pro-inflammatory cytokines,immunoglobulin(Ig)E,Ig G1,and Th2 cytokines including interleukin(IL)-4,while increased serum levels of Th1 cytokines including interferon-γand regulatory T cells(Tregs)cytokines including IL-10 and transforming growth factor-β.MFGM modulated gut microbiota and enhanced intestinal barrier of BLG-allergic mice,as evidenced by decreased relative abundance of Desulfobacterota,Rikenellaceae,Lachnospiraceae,and Desulfovibrionaceae,while increased relative abundance of Bacteroidetes,Lactobacillaceae and Muribaculaceae,and enhanced expressions of tight junction proteins including Occludin,Claudin-1 and zonula occludens-1.Furthermore,MFGM increased fecal short-chain fatty acids(SCFAs)levels,which elevated G protein-coupled receptor(GPR)43 and GPR109A expressions.The increased expressions of GPR43 and GPR109A induced CD103+dendritic cells accumulation and promoted Tregs differentiation in mesenteric lymph node to a certain extent.In summary,MFGM alleviated CMA in a BLG-induced allergic mice model through enhancing intestinal barrier and promoting Tregs differentiation,which may be correlated with SCFAs-mediated activation of GPRs.These findings suggest that MFGM may be useful as a promising functional ingredient against CMA.

High-performance and robust high-temperature polymer electrolyte membranes with moderate microphase separation by implementation of terphenyl-based polymers

Acid loss and plasticization of phosphoric acid(PA)-doped high-temperature polymer electrolyte membranes(HT-PEMs)are critical limitations to their practical application in fuel cells.To overcome these barriers,poly(terphenyl piperidinium)s constructed from the m-and p-isomers of terphenyl were synthesized to regulate the microstructure of the membrane.Highly rigid p-terphenyl units prompt the formation of moderate PA aggregates,where the ion-pair interaction between piperidinium and biphosphate is reinforced,leading to a reduction in the plasticizing effect.As a result,there are trade-offs between the proton conductivity,mechanical strength,and PA retention of the membranes with varied m/p-isomer ratios.The designed PA-doped PTP-20m membrane exhibits superior ionic conductivity,good mechanical strength,and excellent PA retention over a wide range of temperature(80–160°C)as well as satisfactory resistance to harsh accelerated aging tests.As a result,the membrane presents a desirable combination of performance(1.462 W cm^(-2) under the H_(2)/O_(2)condition,which is 1.5 times higher than that of PBI-based membrane)and durability(300 h at 160°C and 0.2 A cm^(-2))in the fuel cell.The results of this study provide new insights that will guide molecular design from the perspective of microstructure to improve the performance and robustness of HT-PEMs.

Retinal pigment epithelium–Bruch’s membrane volume in grading of age-related macular degeneration

AIM:To assess the agreement of optical coherence tomography(OCT)algorithm-based retinal pigment epithelium–Bruch’s membrane complex volume(RBV)with fundus photograph-based age-related macular degeneration(AMD)grading.METHODS:Digital color fundus photographs(CFPs)and spectral domain OCT images were acquired from 96 elderly subjects.CFPs were graded according to Age-Related Eye Disease Study(AREDS)classification.OCT image segmentation and RBV data calculation were done with OrionTM software.Univariate and multivariate analyses were performed to find out whether AMD lesion features associated with higher RBVs.RESULTS:RBV correlated with AMD grading(rs=0.338,P=0.001),the correlation was slightly stronger in early AMD(n=52;rs=0.432,P=0.001).RBV was higher in subjects with early AMD compared with those with no AMD lesions evident in fundus photographs(1.05±0.20 vs 0.96±0.13 mm3,P=0.023).In multivariate analysis higher RBVs were associated significantly with higher total drusen(β=0.388,P=0.027)and pigmentation areas(β=0.319,P=0.020)in fundus photographs,whereas depigmentation area(β=-0.295,P=0.015)associated with lower RBV.CONCLUSION:RBV correlate with AMD grading status,with a stronger association in patients with moderate,non-late AMD grades.This effect is driven mostly by lesions with drusen or pigmentation.Lesions with depigmentation tend to have lower values.RBV is more comprehensive measurement of the key area of AMD pathogenesis,compared to sole drusen volume analysis.RBV measurements are independent on grader variations and offer a possibility to quantify early and middle grade AMD lesions in a research setting,but may not substitute fundus photograph-based grading in the whole range of AMD spectrum.

Fractional Noether theorem and fractional Lagrange equation of multi-scale mechano-electrophysiological coupling model of neuron membrane

Noether theorem is applied to a variable order fractional multiscale mechano-electrophysiological model of neuron membrane dynamics.The variable orders fractional Lagrange equation of a multiscale mechano-electrophysiological model of neuron membrane dynamics is given.The variable orders fractional Noether symmetry criterion and Noether conserved quantities are given.The forms of variable orders fractional Noether conserved quantities corresponding to Noether symmetry generators solutions of the model under different conditions are discussed in detail,and it is found that the expressions of variable orders fractional Noether conserved quantities are closely dependent on the external nonconservative forces and material parameters of the neuron.

Macular Bruch's membrane defects and other myopic lesions in high myopia

AIM: To compare the ocular fundus features of highly myopic eyes with and without macular Bruch’s membrane(BM) defects and investigate the associations between macular BM defects and other myopic lesions.METHODS: This retrospective, observational case series included 262 eyes(139 patients) with high myopia(HM) refractive error ≥-6.0 diopters(D) or axial length ≥26.5 mm from March 2019 to December 2019.The patients underwent a comprehensive ophthalmic examination, including sweptsource optical coherence tomography(SS-OCT).The features of macular BM defects and other ocular fundus lesions were examined in OCT images.RESULTS: Totally 51 eyes(19.5%) were detected with macular BM defects, which were characterized by a lack of BM, retinal pigment epithelium(RPE), and an almost complete loss of photoreceptors or choriocapillaris.Eyes with macular BM defects had worse best-corrected visual acuity(BCVA) than those without(P<0.001).Dome-shaped macula(DSM, P=0.042), retinal cysts(P=0.006), choroidal neovascularization(CNV, P<0.001), choroidal defects and abnormality(P=0.003), scleral defects(P=0.015), scleral deformation(P=0.005), posterior staphyloma(P=0.011), and perforating vessels(P<0.001) occurred more frequently in eyes with macular BM defects.In multivariate analysis, the presence of macular BM defects remained the significant association with presence of DSM(P=0.013), scleral defects(P=0.015), posterior staphyloma(P=0.001), perforating vessels(P<0.001) and CNV(P=0.004).CONCLUSION: Macular BM defects has a prevalence of approximately 20% in HM and it has tight association with other myopic fundus lesions.BM might be crucial in the pathogenesis of myopic fundus lesions due to its biomechanical function.A comprehensive understanding of BM’s role is useful for further researches about myopic lesions.

Lipid accumulation and protein modifications of Bruch’s membrane in age-related macular degeneration

Age-related macular degeneration(AMD)is a progressive retinal disease,which is the leading cause of blindness in western countries.There is an urgency to establish new therapeutic strategies that could prevent or delay the progression of AMD more efficiently.Until now,the pathogenesis of AMD has remained unclear,limiting the development of the novel therapy.Bruch’s membrane(BM)goes through remarkable changes in AMD,playing a significant role during the disease course.The main aim of this review is to present the crucial processes that occur at the level of BM,with special consideration of the lipid accumulation and protein modifications.Besides,some therapies targeted at these molecules and the construction of BM in tissue engineering of retinal pigment epithelium(RPE)cells transplantation were listed.Hopefully,this review may provide a reference for researchers engaged in pathogenesis or management on AMD.

Structure-function relationship comparison between retinal nerve fibre layer and Bruch's membrane opening-minimum rim width in glaucoma

AIM：To evaluate and compare structural optical coherence tomography（OCT）-based parameters,such as Bruch’s membrane opening-minimum rim width（BMO-MRW）,and retinal nerve fiber layer（RNFL）thickness in glaucoma patients with visual field（VF）defects,and to correlate both to mean deviation（MD）values of obtained standard achromatic perimetry（SAP）examinations.METHODS：Patients with glaucoma and glaucomatous VF defects were enrolled in this prospective study and compared to age-matched healthy individuals.All study participants underwent a full ophthalmic examination and VF testing with SAP.Peripapillary RNFL thickness and BMO-MRW were acquired with SD-OCT.Correlation analyses between obtained global functional and global as well as sectorial structural parameters were calculated.RESULTS：A consecutive series of 30 glaucomatous right eyes of 30 patients were included and compared to 36healthy right eyes of 36 individuals in the control group.Global MD of values correlated significantly with global RNFL（Pearson corr.coeff：0.632,P=0.001）and global BMO-MRW（Pearson corr.coeff：0.746,P〈0.001）values in the glaucoma group.Global MD and sectorial RNFL or BMO-MRW values correlated less significantly.In the control group,MD values did not correlate with RNFL or BMO-MRW measurements.A subgroup analysis of myopic patients（〉4 diopters）within the glaucoma group（n=6）revealed a tendency for higher correlations between MD and BMO-MRW than MD and RNFL measurements.CONCLUSION：In a clinical setting,RNFL thickness and BMO-MRW correlate similarly with global VF sensitivity in glaucoma patients with BMO-MRW showing higher correlations in myopic glaucoma patients.

Bruch's membrane opening-minimum rim width and visual field loss in glaucoma:a broken stick analysis

AIM：To determine the Bruch＇s membrane opening-minimum rim width（BMO-MRW） tipping point where corresponding visual field（VF） damages become detectable.METHODS：A total of 85 normal subjects and 83 glaucoma patients（one eye per participant） were recruited for the study.All of the patients had VF examinations and spectral-domain optical coherence tomography to measure the BMO-MRW.Total deviation values for 52 VF points were allocated to the corresponding sector according to the Garway-Heath distribution map.To evaluate the relationship between VF loss and BMOMRW measurements,a ＂broken-stick＂ statistical model was used.The tipping point where the VF values started to sharply decrease as a function of BMO-MRW measurements was estimated and the slopes above and below this tipping point were compared.RESULTS：A 25.9% global BMO-MRW loss from normative value was required for the VF loss to be detectable.Sectorally,substantial BMO-MRW thinning in inferotemporal sector（33.1%） and relatively less BMO-MRW thinning in the superotemporal sector（8.9%） were necessary for the detection of the VF loss.Beyond the tipping point,the slopes were close to zero throughout all of the sectors and the VF loss was unrelated to the BMO-MRW loss.The VF loss was related to the BMO-MRW loss below the tipping point.The difference between the two slopes was statistically significant（P≤0.002）.CONCLUSION：Substantial BMO-MRW loss appears to be necessary for VF loss to be detectable in patients with open angle glaucoma with standard achromatic perimetry.

A cascade of in situ conversion of bicarbonate to CO_(2) and CO_(2) electroreduction in a flow cell with a Ni-N-S catalyst

Combination of CO_(2) capture using inorganic alkali with subsequently electrochemical conversion of the resultant HCO_(3)^(-)to high-value chemicals is a promising route of low cost and high efficiency.The electrochemical reduction of HCO_(3)^(-)is challenging due to the inaccessible of negatively charged molecular groups to the electrode surface.Herein,we adopt a comprehensive strategy to tackle this challenge,i.e.,cascade of in situ chemical conversion of HCO_(3)^(-)to CO_(2) and CO_(2) electrochemical reduction in a flow cell.With a tailored Ni-N-S single atom catalyst(SACs),where sulfur(S)atoms located in the second shell of Ni center,the CO_(2)electroreduction(CO_(2)ER)to CO is boosted.The experimental results and density functional theory(DFT)calculations reveal that the introduction of S increases the p electron density of N atoms near Ni atom,thereby stabilizing^(*)H over N and boosting the first proton coupled electron transfer process of CO_(2)ER,i.e.,^(*)+e^(-)+^(*)H+^(*)CO_(2)→^(*)COOH.As a result,the obtained catalyst exhibits a high faradaic efficiency(FE_(CO)~98%)and a low overpotential of 425 mV for CO production as well as a superior turnover frequency(TOF)of 47397 h^(-1),outcompeting most of the reported Ni SACs.More importantly,an extremely high FECOof 90%is achieved at 50 mA cm^(-2)in the designed membrane electrode assembly(MEA)cascade electrolyzer fed with liquid bicarbonate.This work not only highlights the significant role of the second coordination on the first coordination shell of the central metal for CO_(2)ER,but also provides an alternative and feasible strategy to realize the electrochemical conversion of HCO_(3)^(-)to high-value chemicals.

Using an Anion Exchange Membrane to Predict Soil Available N and S Supplies and the Impact of N and S Fertilization on Canola and Wheat Growth

A growth chamber study was conducted to determine the relationships between the supply of soil available nitrogen (N) and sulfur (S) and canola (Brassica napus) and wheat (Triticum aestivum L. 'Biggar') N and S uptake and yield in three Western Canadian soils. The suitability of one-hour burial with an anion exchange membrane (AEM) was assessed for its utility as a quick test of the available N:S balance in the soil. Canola and wheat were grown on a Luvisolic soil low in available S and on Brown and Black Chernozemic soils low in both available N and S, with different rates and combinations of N and S fertilizers applied. AEM burial was used to assess soil available nitrate and sulfate supply rates after fertilization. Dry matter yield and N and S concentrations in plant tissues were determined after 6 weeks of growth. The soil available N:S ratio determined by AEM burial closely reflected the relative supplies of available N and S as revealed in the N:S ratios of plant tissue dry matter. The highest yields were achieved where the available N:S ratio in soil and plant tissue ranged from 5 to 13. Thus, a one-hour burial of an AEM probe in the field may be a useful tool to quickly test if a balanced N and S supply is present in the soil for optimum crop yield.

Descemet＇s membrane detachments post cataract surgery：a management paradigm

Descemet’s membrane detachments （DMD） are relatively common after cataract surgery and most do not require any treatment. However, if large DMD are not treated appropriately, significant visual morbidity can ensue. We aim to develop a guideline for the management of DMD post cataract surgery based on a retrospective review of all cases encountered at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia over a 4-year period from 2010 to 2014. We suggest conservative management if the visual axis is not involved; however, after 3mo surgical intervention may be warranted to prevent corneal sequelae. In cases where the visual axis is involved we suggest early intervention with air tamponade. The main risk factor for irreversible corneal oedema and subsequent endothelial transplant appears to be direct endothelial trauma rather than the DMD itself.

Bacterial diversity in activated sludge from a consecutively aerated submerged membrane bioreactor treating domestic wastewater

The bacterial diversity of activated sludge from submerged membrane bioreactor (SMBR) was investigated. A 16S rDNA clone library was generated, and 150 clones were screened using restriction fragment length polymorphism (RFLP). Of the screened clones, almost full-length 16S rDNA sequences of 64 clones were sequenced. Phylogenetic tree was constructed with a database containing clone sequences from this study and bacterial rDNA sequences from NCBI for identification purposes. The 90.6% of the clones were a?l...

Subcellular localization of alpha-synuclein aggregates and their interaction with membranes

For more than a decade numerous evidence has been reported on the mechanisms of toxicity of α-synuclein（αS） oligomers and aggregates in α-synucleinopathies.These species were thought to form freely in the cytoplasm but recent reports of αS multimer conformations when bound to synaptic vesicles in physiological conditions,have raised the question about where αS aggregation initiates.In this review we focus on recent literature regarding the impact on membrane binding and subcellular localization of αS toxic species to understand how regular cellular function of αS contributes to pathology.Notably αS has been reported to mainly associate with specific membranes in neurons such as those of synaptic vesicles,ER/Golgi and the mitochondria,while toxic species of αS have been shown to inhibit,among others,neurotransmission,protein trafficking and mitochondrial function.Strategies interfering with αS membrane binding have shown to improve αS-driven toxicity in worms and in mice.Thus,a selective membrane binding that would result in a specific subcellular localization could be the key to understand how aggregation and pathology evolves,pointing out to αS functions that are primarily affected before onset of irreversible damage.

Mathematical Model of Natural Gas Desulfurization Based on Membrane Absorption

Models of mass transfer kinetics combined with mass transfer differential equation and mass transfer resistance equation were established on the basis of double-film theory. Mass transfer process of H2 S absorption by means of polypropylene hydrophobic microporous hollow fiber membrane contactor was simulated using MDEA(N-methyldiethanolamine) as the absorption liquid and corresponding experiments of natural gas desulfurization were performed. The simulation results indicated that the removal rate of hydrogen sulfide showed positive dependence on the absorption liquid concentration and gas pressure. However, the desulfurization rate showed negative dependence on gas flow. The simulated values were in good agreement with the experimental results. The in-tube concentration of hydrogen sulfide at the same point increased with increase in the gas velocity. Axial concentration of hydrogen sulfide decreased rapidly at the beginning, and the decrease saw a slowdown during the latter half period. Hydrogen sulfide concentration dropped quickly in the radial direction, and the reduction in the radial direction was weakened with the increase of axial length due to the gradual reduction of hydrogen sulfide concentration along the tube. The desulfurization rate under given operating conditions can be predicted by this model, and the theoretical basis for membrane module design can also be provided.

JTE-522-induced apoptosis in human gastric adenocarinoma cell line AGS cells by caspase activation accompanying cytochrome C release,membrane translocation of Bax and loss of mitochondrial membrane potential

AIM: To investigate the role of the mitochondrial pathway in JTE-522-induced apoptosis and to investigate the relationship between cytochrome C release, caspase activity and loss of mitochondrial membrane potential (Deltapsim). METHODS: Cell culture, cell counting, ELISA assay, TUNEL, flow cytometry, Western blot and fluorometric assay were employed to investigate the effect of JTE-522 on cell proliferation and apoptosis in AGS cells and related molecular mechanism. RESULTS: JTE-522 inhibited the growth of AGS cells and induced the apoptosis. Caspases 8 and 9 were activated during apoptosis as judged by the appearance of cleavage products from procaspase and the caspase activities to cleave specific fluorogenic substrates. To elucidate whether the activation of caspases 8 and 9 was required for the apoptosis induction, we examined the effect of caspase-specific inhibitors on apoptosis. The results showed that caspase inhibitors significantly inhibited the apoptosis induced by JTE-522. In addition, the membrane translocation of Bax and cytosolic release of cytochrome C accompanying with the decrease of the uptake of Rhodamin 123, were detected at an early stage of apoptosis. Furthermore, Bax translocation, cytochrome C release, and caspase 9 activation were blocked by Z-VAD.fmk and Z-IETD-CHO. CONCLUSION: The present data indicate a crucial association between activation of caspases 8, 9, cytochrome C release, membrane translocation of Bax, loss of Deltapsim and JTE-522-induced apoptosis in AGS cells.

Enhanced gas separation performance of mixed matrix hollow fiber membranes containing post-functionalized S-MIL-53

Mixed matrix hollow fiber membranes（MMHFMs）filled with metal-organic frameworks（MOFs）have great potential for energy-efficient gas separation processes,but the major hurdle is polymer/MOFs interfacial defects and membrane plasticization.Herein,lab-synthesized MIL-53 was post-functionalized by aminosilane grafting and subsequently incorporated into Ultem-1000 polymer matrix to fabricate high performance MMHFMs.SEM,DLS,XRD and TGA were performed to characterize silane-modified MIL-53（S-MIL-53）and prepared MMHFMs.Moreover,the effect of MOFs loading was systematically investigated first;then gas separation performance of MMHFMs for pure and mixed gas was evaluated under different pressures.MMHFMs containing post-functionalized S-MIL-53 achieved remarkable gas permeation properties which was better than model predictions.Compared to pure HFMs,CO2permeance of MMHFM loaded with 15%S-MIL-53 increased by 157%accompanying with 40%increase for CO2/N2selectivity,which outperformed the MMHFM filled with naked MIL-53.The pure and mixed gas permeation measurements with elevated feed pressure indicated that incorporation of S-MIL-53 also increased the resistance against CO2plasticization.This work reveals that post-modified MOFs embedded in MMHFMs facilitate the improvement of gas separation performance and suppression of membrane plasticization.

Analysis of H_2S Tolerance of Pd-Cu Alloy Hydrogen Separation Membranes

The presence of a limited amount of H2S in H2-rich feed adversely affects the Pd-Cu membrane permeation performance due to the sulphidization of the membrane surface. A theoretical model was proposed to predict the S-tolerant performance of the Pd-Cu membranes in presence of H2S under the industrial water-gas-shift(WGS) reaction conditions. The ideas of surface coverage and competitive adsorption thermodynamics of H2S and H2 on Pd-Cu surface were introduced in the model. The surface sulphidization of the Pd-Cu membranes mainly depended on the pressure ratio of H2S to H2, temperature and S-adsorbed surface coverage, i.e., the occurrence of sulphidization on the surface was not directly related with the bulk compositions and structures [body centered cubic and face centered cubic(bcc or fcc)] of Pd-Cu alloy membranes because of the surface segregation phenomena. The resulting equilibrium equations for the H2S adsorption/sulphidization reactions were solved to calculate the pressure ratio of H2S to H2 over a wide range of temperatures. A validation of the model was performed through a comparison between lots of literature data and the model calculations over a rather broad range of operating conditions. An extremely good agreement was obtained in the different cases, and thus, the model can serve to guide the development of S-resistant Pd alloy membrane materials for hydrogen separation.

AB047.Membrane binding of S100A10 protein and AHNAK peptide involved in cell membrane repair

Background:The S100A10 protein might be an early biomarker of diabetes development leading to diabetic retinopathy.The protein complex S100A10/annexin A2 allows the recruitment of the C-terminal of AHNAK protein(AHNAK C-ter peptide)to the membrane in presence of calcium,before forming a platform which can initiate membrane repair.However,no molecular data are currently available on membrane binding of the different proteins involved in this complex.We aim to study the membrane binding of S100A10,AHNAK C-ter peptide and their complex to better understand their roles in cell membrane repair process.Methods:Firstly,S100A10 will be overexpressed and purified by affinity chromatography and AHNAK C-ter peptide will be synthesized.Langmuir monolayers membrane model will then be used to characterize the interactions between these proteins and different phospholipids found in membranes.The secondary structure,orientation and membrane organization of these proteins will be studied by Polarization Modulation Infrared Reflection-Absorption Spectroscopy.Their lateral localization will be determined through the influence of these proteins on the physical state of lipids by fluorescence microscopy.Results:The optimization of the overexpression,purification and cleavage of the GST tag procedure to obtain pure S100A10 was completed.Protein identification by mass spectrometry and circular dichroism stability pre-studies were performed.In parallel,AHNAK C-ter peptide was studied by Langmuir monolayer model and the results indicate this peptide prefers lipids with negatively charged polar heads and unsaturated acyl chains.Preliminary solid-state NMR results confirm this phenomenon at 37℃.Conclusions:Our research will complete current knowledge on membrane binding of S100A10 and AHNAK C-ter peptide.We could also identify the conditions leading to modifications of these membrane bindings,and possibly to the loss of protein function.Thus,this project helps to better determine their roles in membrane repair,as well as in other physiological mechanisms in which these proteins are involved.