Comparison Of Poly Research Articles

Impact of Annealing Chemistry on the Properties and Performance of Microporous Annealed Particle Hydrogels.

Microporous annealed particle (MAP) hydrogels are a promising class of in situ-forming scaffolds for tissue repair and regeneration. While an expansive toolkit of annealing chemistries has been described, the effects of different annealing chemistries on MAP hydrogel properties and performance have not been studied. In this study, we address this gap through a controlled head-to-head comparison of poly(ethylene glycol) (PEG)-based MAP hydrogels that were annealed using tetrazine-norbornene and thiol-norbornene click chemistry. Characterization of material properties revealed that tetrazine click annealing significantly increases MAP hydrogel shear storage modulus and results in slower in vitro degradation kinetics when microgels with a higher cross-link density are used. However, these effects are muted when the MAP hydrogels are fabricated from microgels with a lower cross-link density. In contrast, in vivo testing in murine critical-sized calvarial defects revealed that these differences in physicochemical properties do not translate to differences in bone volume or calvarial defect healing when growth-factor-loaded MAP hydrogel scaffolds are implanted into mouse calvarial defects. Nonetheless, the impact of tetrazine click annealing could be important in other applications and should be investigated further.

A comparison of poly (3,4-ethylenedioxythiophene) polymerized potentiostatically and galvanostatically

Conducting polymer films, such as polypyrrole (PPy), have been extensively studied as linear actuators. Poly (3,4-ethylendioxythiophene) (PEDOT) received less attention as linear actuators, even though they show much better stability and conductivity than PPy films. In this work, we investigate the actuation of PEDOT films of comparable thicknesses electropolymerized either, potentiostatically (PEDOT (pot)) and galvanostatically (PEDOT (galv)) in the same organic electrolyte. Characterization by cyclic voltammetry and chronoamperometry revealed that the actuation direction of these films is opposite to each other: in PEDOT (pot) films show cation-driven actuation, while for PEDOT (galv) films present anion-driven actuation. The measured strain of PEDOT (pot) was found to be 1.4 times larger than that of PEDOT (galv), involving 1.5 times higher charge density and having 2.3 times higher electronic conductivity. The specific capacitance, measured by cyclic voltammetry and chronopotentiometry, showed that PEDOT (pot) has double energy storage capabilities to that of PEDOT (galv), keeping up to 86.7% of the storage capacity after 5000 charge/discharge cycles. Further characterization of the PEDOT samples was performed by means of scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDX) and Raman spectroscopy.

Injection moulding of micropillar arrays: a comparison of poly(methyl methacrylate) and cyclic olefin copolymer

Injection moulding of micropillar arrays offers a fast and inexpensive method for manufacturing sensors, optics, lab-on-a-chip devices, and medical devices. Material choice is important for both the function of the device and manufacturing optimisation. Here, a comparative study of poly(methyl methacrylate) (PMMA) and cyclic olefin copolymer (COC) injection moulding of micropillar arrays is presented. These two polymers are chosen for their convenient physical, chemical, and optical properties, which are favoured for microfluidic devices. COC is shown to replicate the mould’s nano/microstructures more precisely than PMMA. COC successfully forms a micropillar array (250 mm diameter; 496 mm high) and closely replicates surfaces with nano-scale roughness (30–120 nm). In the same moulds, PMMA forms lens arrays (not true pillars) and smoother surfaces due to the incomplete filling for all parameters studied. Thus, COC offers finer structural detail for devices that require micro and nano-structured features, and may be more suited to injection moulding microfluidic devices.

Synergistic Double Cross-Linked Dynamic Network of Epoxidized Natural Rubber/Glycinamide Modified Polyacrylic Acid for Silicon Anode in Lithium Ion Battery: High Peel Strength and Super Cycle Stability.

Silicon (Si), a high-capacity lithium-ion battery anode material, has aroused wide attention. Its further practical application has been limited by its huge volume change during the cycle. To reduce this defect, the double cross-linked product of glycinamide hydrochloride modified poly(acrylic acid) (PAG) and epoxidized natural rubber (ENR) was developed as a water-based binder to obtain sufficient elasticity and a sufficiently strong adhesive force. Due to the double cross-linked structures in the system, the binder was enabled to effectively disperse and transfer the stress generated by the volume expansion of the Si particles and keep the integrity of the electrode during the cycle, thus obtaining excellent cycle performance. When the current density was 1 A g-1, PE55 (PAG: ENR = 1:1 cross-linked polymer) electrode still achieved a specific capacity of 2322.2 mAh g-1 after 100 cycles of constant current charge and discharge, and PE55 binder exhibited excellent bonding properties (4.45 N) and mechanical properties (stress: 5.51 MPa, strain: 87.4%). The comparison of poly(acrylic acid) (PAA) electrodes suggests that the introduction of elastic polymer and the construction of double cross-linked structures can increase the stability of Si anodes.

Three-dimensional scaffolds for bioengineering of cartilage tissue

The cartilage tissue is neither supplied with blood nor innervated, so it cannot heal by itself. Thus, its reconstruction is highly challenging and requires external support. Cartilage diseases are becoming more common due to the aging population and obesity. Among young people, it is usually a post-traumatic complication. Slight cartilage damage leads to the spontaneous formation of fibrous tissue, not resistant to abrasion and stress, resulting in cartilage degradation and the progression of the disease. For these reasons, cartilage regeneration requires further research, including use of new type of biomaterials for scaffolds. This paper shows cartilage characteristics within its most frequent problems and treatment strategies, including a promising method that combines scaffolds and human cells. Structure and material requirements, manufacturing methods, and commercially available scaffolds were described. Also, the comparison of poly(L-lactide) (PLLA) and polyethersulfone (PES) 3D membranes obtained by a phase inversion method using nonwovens as a pore-forming additives were reported. The scaffolds' structure and the growth ability of human chondrocytes were compared. Scaffolds' structure, cells morphology, and protein presence in the membranes were examined with a scanning electron microscope. The metabolic activity of cells was tested with the MTT assay. The structure of the scaffolds and the growth capacity of human chondrocytes were compared. Obtained results showed higher cell activity and protein content for PES scaffolds than for PLLA. The PES membrane had better mechanical properties (e.g. ripping), greater chondrocytes proliferation, and thus a better secretion of proteins which build up the cartilage structure.

Ionogels as Polymer Electrolytes for Lithium–Metal Batteries: Comparison of Poly(ethylene glycol) Diacrylate and an Imidazolium-Based Ionic Liquid Crosslinker

Ionogels as Polymer Electrolytes for Lithium–Metal Batteries: Comparison of Poly(ethylene glycol) Diacrylate and an Imidazolium-Based Ionic Liquid Crosslinker

Comparison of Poly(Lactic-Co-Glycolic Acid) and Poly(Lactic-Co-Glycolic Acid)/Hyaluronic Acid Based Scaffolds for Chondrogenesis of Human Adipose-derived Stem Cells by Avocado/Soybean Unsaponifiables

Background: Corporation of Hyaluronic acid (HA) with PLGA is an effective way to potentially enhance chondrogenesis. The aim of this study was to use HA macroporous biodegradable poly(lactic acid-co-glycolic acid) [PLGA] scaffold to enhance the attachment, proliferation and differentiation of chondrocytes for cartilage tissue engineering and articular cartilage regeneration of human adipose derived stem cells (hADSCs) in the presence of avocado/soybean unsaponifible (ASU).Methods: The PLGA and PLGA/HA scaffolds were prepared and hADSCs were cultured separately on the scaffolds and 14 days after differentiation, chondrogenic genes in each scaffold evaluated using real time PCR and cell viability examined by (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.Results: The viability and proliferation of cells in-group of PLGA significantly decreased in comparison with the control (P=0.002) and PLGA/HA (P=0.013) groups.The expression of (SOX9), Aggrecan (AGG), and Collagen type II (Col II) genes was significantly higher in the PLGA and PLGA/HA groups compared to the control group (P≥0.05).The gene expression of SOX9 (P=0.003) and AGG (P=0.009) was significantly higher in the PLGA/HA groups compared to the PLGA group. The results of real time PCR showed that collagen type X (Col X) gene expression in the PLGA group, was significantly higher than the control and PLGA/HA groups (P=0.000).Conclusion: The corporation of HA with PLGA is an effective way to potentially enhance chondrogenesis and articular cartilage regeneration of hADSCs in the presence of avocado/soybean unsaponifiables (ASU).

The Effect of Backbone Structure on Functional Properties in Anion Exchange Membranes; Comparison of Poly(fluorene) with Poly(biphenylene) and Poly(terphenylene)s

The irreversible environmental impacts caused by energy generation from fossil fuels calls for a paradigm shift in the energy conversion and storage. Among many alternative energy technologies hydrogen based electrochemical devices gain significance because of its high efficiency and environmentally benign byproduct formation. Ion exchange polymers play a key role in electrochemical devices as solid-state electrolytes conducting ions between the electrodes while acting as a physical barrier to reactants and electrons. Electrochemical reactions carried out under high pH medium in fuel cells and electrolyzers using anion exchange membranes (AEMs) have gained significant traction recently, due to the prospect of using non-platinum group metal electrocatalyst for the redox reactions. While AEMs remain a crucial part of electrochemical devices such as alkaline exchange membrane fuel cells and alkaline electrolyzers, the absence of a suitable membrane is an impediment for the widespread usage of these technologies. Recently our group synthesized several anion exchange polymers via super acid catalyzed Friedel-Crafts polycondensation. These AEMs, BPN1-100, m-TPN1-100 and p-TPN1-100 showed excellent stability in alkaline medium due to the absence of labile aryl-ether bonds in the polymer backbone. Additionally, they also exhibit good ionic conductivities and mechanical properties. In order to further understand the effects of polymer backbone morphology in AEM properties another polymer FMN1-100 was synthesized. In this study, properties of the AEMs BPN1-100, m-TPN1-100, p-TPN1-100, and FMN1-100 (Figure 1) were evaluated and compared for the purpose of anion exchange polymer electrolytes. Furthermore, FMN2-60 and FMN2-50 containing dication side chains were synthesized and compared against FMN1-100 containing a monocation side chain. The effect of the backbone architecture and side chain cations on the AEM properties such as, ionic conductivity, water uptake ratio, mechanical properties, morphology, and alkaline stability were investigated to broaden the knowledge of polymer design for AEMs. Figure 1

Comparison of Poly (ADP-ribose) Polymerase Inhibitors (PARPis) as Maintenance Therapy for Platinum-Sensitive Ovarian Cancer: Systematic Review and Network Meta-Analysis.

Simple SummaryPoly (ADP-ribose) polymerase inhibitors (PARPis; inhibitors of a family of enzymes that are primary involved in DNA repair) are considered to be the drug of choice in maintenance therapy for platinum-sensitive ovarian cancer. However, despite the FDA approval of three such agents and their availability in clinical practice, thus far, no clinical trial investigated them in a head-to-head direct comparison. In this study, we used a statistical approach that allows comparing direct and indirect evidence (network meta-analysis) in order to compare the three FDA-approved PARPis (olaparib, niraparib and rucaparib). To this end, we used data from six randomized control trials involving a total of 2270 ovarian cancer patients. Interestingly, we found no significant differences in clinical outcomes (overall survival and progression-free survival) between the three agents. However, niraparib was found to be associated with higher risk of certain adverse events (thrombocytopenia, neutropenia, constipation, and headaches) compared to the other two PARPis.Background: Three PARPis (olaparib, niraparib and rucaparib) are currently FDA-approved as maintenance therapy in newly diagnosed and recurrent ovarian cancer. However, thus far, no trial has compared the three approved PARPis in the overall population, in patients with BRCA mutations, or in those with wild-type BRCA. Methods: A frequentist network meta-analysis was used for indirect comparisons between the different PARPis with respect to progression free survival (PFS), overall survival (OS), and adverse events. Results: Overall, six randomized clinical trials involving 2,770 patients, were included in the analysis. Results from the indirect comparisons revealed no statistically significant differences between the three PARPis with respect to PFS or OS in the entire population and in patients with mutated and wild-type BRCA, separately. Niraparib showed a statistically significant increased risk for grade 3 and 4 thrombocytopenia (risk-difference [RD] from placebo: 0.3; 95% confidence interval [CI], 0.27‒0.34) and any grade neutropenia (RD from placebo: 0.22; 95% CI, 0.18‒0.25) as compared with the other PARPis. Conclusion: No statistically significant difference was found between the three PARPis with respect to PFS or OS (overall and in subpopulations by BRCA status). There is, however, a statistical difference in toxicity as niraparib is associated with a greater risk for thrombocytopenia and neutropenia.

Formulation of bicelles with cholesterol using a semi-spontaneous method

Stratum corneum intercellular lipids play an important role in skin barrier function and are therefore considered useful in pharmaceutical and cosmetics products. In this study, we formulated cholesterol (Cho), the main component of intercellular lipids, into bicelles using a semi-spontaneous method, with the ultimate aim of extending the utility of bicelles in cosmetics. Bicelles are disk-shaped structures in which the planar part comprises long-chain phospholipids and the rims comprise short-chain phospholipids. We used soybean lecithin (SL) and nonionic surfactants (NS) to formulate Cho into bicelles using a semi-spontaneous method. Cho was successfully formulated into bicelles using poly(oxyethylene) cholesteryl ether (with an average of 10 ethylene oxide units, ChEO10) as the NS. We identified the boundaries of the bicelle region in the SL-Cho-ChEO10 system by measuring particle sizes. A bicelle region was formed up to around a maximum mixing ratio of 10wt% Cho, representing a mole fraction (mol%) of approximately 33. Phase changes in the system were observed. Comparison of poly(oxyethylene) cholesteryl ethers containing an average of 10 or 20 (ChEO20) ethylene oxide units revealed that the size of the hydrophilic group affects both the bicelle formation region and the mixing ratio of Cho. We analyzed the state of the SL-Cho-ChEO10 bicelles by differential scanning calorimetry and found that samples containing only phospholipid (SL/Ch/ChEO10 = 1/0/0) provided an endothermic peak between 50 and 55 °C, corresponding to the gel-liquid crystal transition point of the phospholipid. In contrast, the bicelle regions (SL/Cho/ChEO10 = 0.4/0/0.6 and 0.37/0.05/0.58) lacked a gel liquid crystal transition point and a liquid-ordered state was induced by Cho or ChEO10. This indicates that these bicelles are highly stable towards thermal changes.

Comparison of thermal, structural and morphological properties of poly(L-lactide) and poly(L-lactide)/hydroxyapatite microspheres for laser sintering processes

A comparison of poly(l-lactide) (PLLA) and poly(l-lactide)/hydroxyapatite (PLLA/HAp) biocomposite microspheres fabricated by emulsion solvent evaporation technique designed for laser sintering (LS) applications is presented. Key properties such as thermal and structural as well as geometry, size distribution and powder flowability, which are crucial for this technique, are characterized to validate the applicability of microspheres for LS. The biocomposite microspheres turns out to be more suitable for the LS process than PLLA due to the higher thermal stability, broader sintering window and higher powder flowability.

Understanding of strain-induced crystallization developments scenarios for polyesters: Comparison of poly(ethylene furanoate), PEF, and poly(ethylene terephthalate), PET

Specific conditions of strain, stretching, strain rate and temperature are known to be necessary for the strain induced crystallization phenomenon (SIC) to occur. It leads to the formation of a crystal in different amorphous polymers, stretched above their glassy transition. This phenomenon was intensively documented in case of poly(ethylene terephthalate), PET. More recently, some studies focused on SIC development in biobased poly(ethylene furandicarboxylate), PEF. Comparison of these crystallization abilities and crystallization kinetics upon stretching in the two materials allows to describe main differences between them, and to enlighten the role of chain architecture on SIC. To achieve that point, different mechanical tensile tests were conducted using well controlled loading paths to explore the different steps of the microstructural changes induced by the stretching and their correlation with mechanical behaviour.Several macroscopic equivalence in the effects of SIC were found, such as increase in modulus, appearance of organized phase, increase I n α−relaxation temperature despite some differences in chain architecture. Combining both loading-unloading tests and quenching protocols, it was found that inducing more or less strong interactions between constitutive units, and more or less stable crystalline phases, leads to differences in apparent strain induced crystallization kinetics:• PET stretching can induce, prior to main strain hardening step, the formation of re-enforcing intermediate phases (or imperfect crystal) being stable upon unloading and able to be improved upon relaxation or thermal treatments;• PEF stretching exhibits a more “simple” two-steps path with no intermediate phases stable upon unloading.This can be related with the weaker stability of PEF crystal compared to PET (PEF quiescent crystallization temperature and melting temperature are very close to each other), and to the more complex crystalline lattice in PEF (two units are needed instead of one due to furanic cycle). In addition, for PET, Young modulus increases more gradually during strain hardening than for PEF. The final microstructure after stretching is therefore more dependent on thermomechanical treatments (annealing or relaxation steps) in PET in comparison to PEF.

Poly(ethylene glycol) or poly(2-ethyl-2-oxazoline) – A systematic comparison of PLGA nanoparticles from the bottom up

In times of drastically increasing numbers of scientific reports dealing with the drawbacks of poly(ethylene glycol) (PEG), the search of PEG alternatives has never been more urgent. This study describes a one–to–one comparison of poly(2-ethyl-2-oxazoline)-b-poly(lactic-co-glycolic acid) (PEtOx-b-PLGA) to commercial PEG-b-PLGA from the bottom up in order to verify the similarity of both polymer classes when applied in nanoparticle formulation processes. For this purpose, a library of block copolymers with molar masses (Mn) ranging from 6500 to 60,000 g mol−1 was synthesized via tin-(II)-ethyl hexanoate (SnOct2) catalyzed ring-opening polymerization (ROP) of lactide and glycolide utilizing PEtOx-OH as a macroinitiator in the melt. The PEtOx-b-PLGA polymers were adjusted in terms of molar mass, dispersity and lactide to glycolide ratio of the PLGA block. Nanoparticle formulations showed a similar behavior for both polymer libraries. Zeta potentials as well as hydrodynamic diameter measured by laser light scattering were in excellent agreement, demonstrating the eligibility of PEtOx-b-PLGA as an alternative to formulate “stealth” nanoparticles.

Comparison of poly(ADP-ribose) polymerase inhibitors (PARPi's) as maintenance therapy for platinum-sensitive ovarian cancer: Systematic review and network meta-analysis.

e18070 Background: Over the past decade, 3 PARPi's (olaparib, niraparib and rucaparib) have been approved by the FDA as maintenance therapy for recurrent ovarian cancer. However, thus far, no trial compared the 3 approved PARPi's in the overall population, in patients with BRCA mutations (BRCAm), or in those with wild-type BRCA (BRCAwt). Methods: We performed a systematic review and identified relevant literature from Embase, Pubmed and Cochrane Library. To be included in the analysis, studies had to be phase 2 or 3 randomized controlled trials (RCT) of platinum-sensitive recurrent or newly diagnosed ovarian cancer, randomized to placebo or PARPi as maintenance therapy and where complete or partial response was documented. A frequentist network meta-analysis was used for indirect comparisons between the different PARPi's to assess superiority in terms of progression free survival (PFS), overall survival (OS), and adverse events. Results: Overall, 6 RCTs involving 2,770 patients, were included in the network meta-analysis. Results from the indirect comparisons revealed no statistically significant differences between the 3 different PARPi's with respect to OS. PFS results demonstrated a nonsignificant trend supporting superiority for niraparib in all patients as well as in BRCAm patients (Table). Only 2 studies reported OS results for niraparib and none reported OS results for rucaparib. Niraparib showed a statistically significant increased risk for all grade thrombocytopenia and neutropenia. Conclusions: Our analysis demonstrates no statistically significant differences between the 3 PARPi’s in any of the analyzed groups, and a trend supporting PFS superiority for niraparib in all patients and in BRCAm patients, while having greater risk for thrombocytopenia and neutropenia. Additional OS results are pending from current studies, and would be useful for elucidating the relative roles of the different PARPi's in platinum-sensitive ovarian cancer. [Table: see text]

Comparison of poly(ethylene glycol)-based networks obtained by cationic ring opening polymerization of neutral and 1,2,3-triazolium diepoxy monomers

The properties of two cross-linked epoxy networks obtained by ring opening polymerization of a synthetic diepoxy 1,2,3-triazolium and a commercial poly(ethylene glycol)diglycidyl ether using benzylamine trifluoroborate as cationic initiator are compared.

Poly (l-lactic acid) bioresorbable scaffolds versus metallic drug-eluting stents for the treatment of coronary artery disease: A meta-analysis of 11 randomized trials.

Bioresorbable vascular scaffolds (BVS) have been proposed for overcoming the long-term limitations of permanent metallic stents, while theoretically warranting similar advantages in plaque stabilization and anti-restenotic drug delivery in the early postrevascularization phase. However, increased rates of malapposition, restenosis, or thrombosis have emerged from initial trials with BVS, that were nevertheless underpowered for the evaluation of the real outcome benefits of these coronary devices. The recent completion of newer randomized clinical trials paves the way to the present meta-analysis, aiming at the comparison of Poly (l-Lactic acid) BVS (PLLA-BVS) versus metallic drug-eluting stents (DES) in the treatment of coronary stenoses. Literature and main scientific session abstracts were searched for randomized clinical trials (RCTs) comparing drug-eluting BVS versus metallic DES for the treatment of coronary artery disease (CAD). The primary efficacy endpoint was mortality, secondary endpoints were cardiovascular death, myocardial infarction, target lesion revascularization (TLR), stent thrombosis and the composite of device-oriented target lesion failure (TLF). We included 11 randomized trials, for a total population of 10,707 patients, 54.5% treated with BVS. The major indication for PCI was stable CAD, whereas acute coronary syndrome represented 30% of the patients. At a mean follow-up of 2.64 years (1-5 years), mortality occurred in 2.71% of the patients, with no difference according to the type of implanted stent (OR[95%CI] = 0.94 [0.74, 1.20], p = .62). No interaction was observed according to patients' risk profile or the rate of diabetes and ACS. However, a significant increase in myocardial infarction, stent thrombosis, TLR and TLF was observed with BVS as compared to DES. The present meta-analysis provides the most updated data on the use of PLLA-BVS for the treatment of CAD. We documented a poorer performance of these new coronary devices, as compared to new generation metallic DES, being associated with an increased rate of recurrent cardiovascular events. However, such ischemic complications did not impact on mortality, with a comparable survival independently from the type of stent.

Study on the effect of side-chain group on the segmental dynamics of selected methacrylate polymers at ambient and high pressures

In this work, we have investigated the effect of changes in the side groups within the polymer chain on the glass transition dynamics of selected methacrylate polymers. The relaxation dynamics of the studied polymers: poly (glycidyl methacrylate), poly (hydroxy-propyl methacrylate), poly (isopropyl methacrylate) and poly (n-propyl methacrylate), was investigated with the use of dielectric spectroscopy and differential scanning calorimetry. In addition to that, high-pressure dielectric measurements were performed to understand better the effect of density changes on the segmental dynamics within the studied family of compounds. A comparison of poly (isopropyl methacrylate) and poly (n-propyl methacrylate), that have the same chemical composition while differ only in the molecular orientation of the side-chain group, has revealed pronounced differences in the glass transition temperature of almost 26 K and sensitivity of the segmental dynamics to pressure changes.

Comparison of poly(butylene succinate) biodegradation by Fusarium solani cutinase and Candida antarctica lipase

Poly(butylene succinate) (PBS) was hydrolyzed by two different enzymes: cutinase from Fusarium sp. and lipase from Candida antarctica (Lipozyme CALB). The differences between the PBS residues degraded over time were investigated with respect to their morphology, crystallinity and chemical structures. The degradation mechanism of PBS films using the two enzymes was further investigated by establishing a model. The results show that the PBS weight loss when degraded by cutinase was higher than when degraded by Lipozyme CALB under the same conditions. The PBS degradation mechanisms by cutinase and Lipozyme CALB occur by surface erosion and bulk erosion, respectively. Scanning electron microscopy shows that the diameter of pits formed after degradation by cutinase was approximately 3 times larger than those formed by Lipozyme CALB. The change in crystallinity is related to the type of enzyme used during the degradation process. Following Lipozyme CALB degradation, the degree of PBS crystallinity decreased with increasing time, leading to increased weight loss of the PBS films. Conversely, the PBS crystallinity was nearly unchanged following cutinase degradation. Powder X-ray diffraction indicates that the crystalline structure does not change during enzymatic hydrolysis. Fourier transform infrared spectroscopy confirms that the resulting structure of the degraded PBS is similar when treated with cutinase and Lipozyme CALB. Mass-spectrometric analysis suggested an endo-type action mode for both the enzymes.

Comparison of poly(styrene-divinylbenzene)-based monolithic and bead-based methodologies used in NANOFLOW LCMS for proteomic studies

The SDVB-based monolithic chromatography combined with electrospray mass spectrometry is a powerful tool in proteomics analysis.

Nanodefect-controlled permeation in AlOx/polymer gas barrier films

The permeation of water vapour through a coated polymer gas barrier film is controlled by the defects in the coating. By modelling these defects as a combination of macro-defects (in which the activation energy of permeation is that of the underlying polymer substrate) and nano-defects (in which the activation energy of permeation is something greater than that of the polymer substrate), we are able to understand the mechanisms of permeation in high gas barrier layers. Permeation is controlled by the amounts of such defects, with the observed overall activation energy informing us of the relative permeation through macro- and nano-defects. Three examples of aluminium oxide (AlOx)-coated polymers are given to illustrate this: a comparison of poly(ethylene naphthalate) and polypropylene (OPP) substrates, the role of sputter power in AlOx/OPP films and the role of oxide thickness in AlOx/OPP films. When the amount of permeation through macro-defects is quite low, and hence nano-defect permeation is a significant proportion of the overall water vapour transport, control of each of the two defect types becomes important. Contrary to what has been previously assumed, the activation energy can be observed as greater in some cases in which the overall permeation is also greater, and this can be explained by an increase in the proportion of permeation taking place through nanodefects. This model is evidenced by reference to microstructural and other characterisation, and hence gives rise to understanding of the relationship between process properties, microstructure and permeation.