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Zare F, Gonçalves SB, Faria M, Gonçalves MC. Improving Structural Homogeneity, Hydraulic Permeability, and Mechanical Performance of Asymmetric Monophasic Cellulose Acetate/Silica Membranes: Spinodal Decomposition Mix. Membranes (Basel) 2023; 13:346. [PMID: 36984734 PMCID: PMC10059883 DOI: 10.3390/membranes13030346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/01/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
In this paper, we propose an optimized protocol to synthesize reproducible, accurate, sustainable integrally skinned monophasic hybrid cellulose acetate/silica membranes for ultrafiltration. Eight different membrane compositions were studied, divided into two series, one and two, each composed of four membranes. The amount of silica increased from 0 wt.% up to 30 wt.% (with increments of 10 wt.%) in each series, while the solvent composition was kept constant within each series (formamide/acetone ratio equals 0.57 wt.% in series one and 0.73 wt.% in series two). The morphology of the membranes was analyzed by scanning electron microscopy and the chemical composition by Fourier transform infrared spectroscopy, in attenuated total reflection mode (FTIR-ATR). Mechanical tensile properties were determined using tensile tests, and a retest trial was performed to assess mechanical properties variability over different membrane batches. The hydraulic permeability of the membranes was evaluated by measuring pure water fluxes following membrane compaction. The membranes in series two produced with a higher formamide/acetone solvent ratio led to thicker membranes with higher hydraulic permeability values (47.2-26.39 kg·h-1·m-2·bar-1) than for the membranes in series one (40.01-19.4 kg·h-1·m-2·bar-1). Results obtained from the FTIR-ATR spectra suggest the presence of micro/nano-silica clusters in the hybrid membranes of series one, also exhibiting higher Young's modulus values than the hybrid membranes in series two.
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Affiliation(s)
- Fahimeh Zare
- Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Centro de Química Estrutural (CQE), 1049-001 Lisboa, Portugal
| | - Sérgio B. Gonçalves
- IDMEC, Instituto de Engenharia Mecânica, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Mónica Faria
- Center of Physics and Engineering of Advanced Materials (CeFEMA), Laboratory for Physics of Materials and Emerging Technologies (LaPMET), Chemical Engineering Department, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisbon, Portugal
| | - Maria Clara Gonçalves
- Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
- Centro de Química Estrutural (CQE), 1049-001 Lisboa, Portugal
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Behrangzade A, Keeney HR, Martinet KM, Wagner WR, Vande Geest JP. Mechanical alterations of electrospun poly(ϵ-caprolactone) in response to convective thermobonding. J Biomed Mater Res B Appl Biomater 2023; 111:622-632. [PMID: 36221771 PMCID: PMC10600560 DOI: 10.1002/jbm.b.35181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 09/07/2022] [Accepted: 09/22/2022] [Indexed: 01/21/2023]
Abstract
Vascular graft failure has persisted as a major clinical problem. Mechanical, structural, and transport properties of vascular grafts are critical factors that substantially affect their function and thus the outcome of implantation. The manufacturing method, post-processing technique, and material of choice have a significant impact on these properties. The goal of this work is to use thermal treatment to modulate the transport properties of PCL-based vascular engineered constructs. To this end, we electrospun PCL tubular constructs and thermally bonded the electrospun fibers in a convective oven at various temperatures (54, 57, and 60°C) and durations of treatment (15, 30, and 45 s). The effects of fiber thermal bonding (thermobonding) on the transport, mechanical, and structural properties of PCL tubular constructs were characterized. Increasing the temperature and treatment duration enhanced the degree of thermobonding by removing the interconnected void and fusing the fibers. Thermobonding at 57°C and 60°C for longer than 30 s increased the median tangential modulus (E = 126.1 MPa, [IQR = 20.7]), mean suture retention (F = 193.8 g, [SD = 18.5]), and degradation rate while it decreased the median permeability (kA = 0 m/s), and median thickness (t = 60 μm, [IQR = 2.5]). In particular, the thermobonding at 57°C allowed a finer modulation of permeability via treatment duration. We believe that the thermobonding method can be utilized to modulate the properties of vascular engineered constructs which can be useful in designing functional vascular grafts.
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Affiliation(s)
- Ali Behrangzade
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Hannah R. Keeney
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Katarina M. Martinet
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - William R. Wagner
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Chemical Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jonathan P. Vande Geest
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Department of Mechanical Engineering and Material Science, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
- Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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3
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Abstract
In haemodialysis (HD), unwanted substances (uraemic retention solutes or ‘uraemic toxins’) that accumulate in uraemia are removed from blood by transport across the semipermeable membrane. Like all membrane separation processes, the transport requires driving forces to facilitate the transfer of molecules across the membrane. The magnitude of the transport is quantified by the phenomenon of ‘flux’, a finite parameter defined as the volume of fluid (or permeate) transferred per unit area of membrane surface per unit time. In HD, as transmembrane pressure is applied to facilitate fluid flow or flux across the membrane to enhance solute removal, flux is defined by the ultrafiltration coefficient (KUF; mL/h/mmHg) reflecting the hydraulic permeability of the membrane. However, in HD, the designation of flux has come to be used in a much broader sense and the term is commonly used interchangeably and erroneously with other measures of membrane separation processes, resulting in considerable confusion. Increased flux is perceived to reflect more ‘porous’ membranes having ‘larger’ pores, even though other membrane and therapy attributes determine the magnitude of flux achieved during HD. Adjectival designations of flux (low-, mid-, high-, super-, ultra-) have found indiscriminate usage in the scientific literature to qualify a parameter that influences clinical decision making and prescription of therapy modalities (low-flux or high-flux HD). Over the years the concept and definition of flux has undergone arbitrary and periodic adjustment and redefinition by authors in publications, regulatory bodies (US Food and Drug Administration) and professional association guidelines (European Renal Association, Kidney Disease Outcomes Quality Initiative), with little consensus. Industry has stretched the boundaries of flux to derive marketing advantages, justify increased reimbursement or contrive new classes of therapy modalities when in fact flux is just one of several specifications that determine membrane or dialyser performance. Membranes considered as high-flux previously are today at the lower end of the flux spectrum. Further, additional parameters unrelated to the rate of diffusive or convective transport (flux) are used in conjunction with or in place of KUF to allude to flux: clearance (mL/min, e.g. of β2-microglobulin) or sieving coefficients (dimensionless). Considering that clinical trials in nephrology, designed to make therapy recommendations and guide policy with economic repercussions, are based on the parameter flux they merit clarification—by regulatory authorities and scientists alike—to avoid further misappropriation.
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Affiliation(s)
- Sudhir K Bowry
- Dialysis-at-Crossroads (D@X) Advisory, Bad Nauheim, Germany
| | - Fatih Kircelli
- Global Medical Information and Education, Fresenius Medical Care, Bad Homburg, Germany
| | - Madhukar Misra
- Department of Medicine, Division of Nephrology, University of Missouri, Columbia, MO, USA
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Liu Z, Wang Y, Guo F. An Investigation into Hydraulic Permeability of Fibrous Membranes with Nonwoven Random and Quasi-Parallel Structures. Membranes (Basel) 2021; 12:54. [PMID: 35054580 DOI: 10.3390/membranes12010054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 12/28/2021] [Accepted: 12/30/2021] [Indexed: 11/17/2022]
Abstract
Fibrous membranes with a nonwoven random structure and a quasi-parallel fibrous structure can be fabricated by the electrospinning technique. The membranes with different structures exhibited different behaviors to a hydraulic flow passing through the membranes. This work presents the effects of the fiber arrangement, fiber diameter, and deformations of the fibers on the hydraulic permeability. The results showed that the hydraulic flow can generate an extrusion pressure which affects the porosity and pore structure of the fibrous membranes. The quasi-parallel fibrous membranes and nonwoven membranes exhibited similar variation tendencies to the change of the experimental variables. However, the quasi-parallel fibrous membranes exhibited a higher sensibility to the change of the hydraulic flow rate. The hydraulic permeability of the quasi-parallel fibrous membranes was further analyzed with packing state models in this work.
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Vidotto M, Bernardini A, Trovatelli M, De Momi E, Dini D. On the microstructural origin of brain white matter hydraulic permeability. Proc Natl Acad Sci U S A 2021; 118:e2105328118. [PMID: 34480003 DOI: 10.1073/pnas.2105328118] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 07/26/2021] [Indexed: 11/18/2022] Open
Abstract
Brain microstructure plays a key role in driving the transport of drug molecules directly administered to the brain tissue, as in Convection-Enhanced Delivery procedures. The proposed research analyzes the hydraulic permeability of two white matter (WM) areas (corpus callosum and fornix) whose three-dimensional microstructure was reconstructed starting from the acquisition of electron microscopy images. We cut the two volumes with 20 equally spaced planes distributed along two perpendicular directions, and, on each plane, we computed the corresponding permeability vector. Then, we considered that the WM structure is mainly composed of elongated and parallel axons, and, using a principal component analysis, we defined two principal directions, parallel and perpendicular, with respect to the axons' main direction. The latter were used to define a reference frame onto which the permeability vectors were projected to finally obtain the permeability along the parallel and perpendicular directions. The results show a statistically significant difference between parallel and perpendicular permeability, with a ratio of about two in both the WM structures analyzed, thus demonstrating their anisotropic behavior. Moreover, we find a significant difference between permeability in corpus callosum and fornix, which suggests that the WM heterogeneity should also be considered when modeling drug transport in the brain. Our findings, which demonstrate and quantify the anisotropic and heterogeneous character of the WM, represent a fundamental contribution not only for drug-delivery modeling, but also for shedding light on the interstitial transport mechanisms in the extracellular space.
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Shaheen R, Gurlin RE, Gologorsky R, Blaha C, Munnangi P, Santandreu A, Torres A, Carnese P, Nair GG, Szot G, Fissell WH, Hebrok M, Roy S. Superporous agarose scaffolds for encapsulation of adult human islets and human stem-cell-derived β cells for intravascular bioartificial pancreas applications. J Biomed Mater Res A 2021; 109:2438-2448. [PMID: 34196100 DOI: 10.1002/jbm.a.37236] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/14/2021] [Accepted: 05/11/2021] [Indexed: 12/12/2022]
Abstract
Type 1 diabetic patients with severe hypoglycemia unawareness have benefitted from cellular therapies, such as pancreas or islet transplantation; however, donor shortage and the need for immunosuppression limits widespread clinical application. We previously developed an intravascular bioartificial pancreas (iBAP) using silicon nanopore membranes (SNM) for immunoprotection. To ensure ample nutrient delivery, the iBAP will need a cell scaffold with high hydraulic permeability to provide mechanical support and maintain islet viability and function. Here, we examine the feasibility of superporous agarose (SPA) as a potential cell scaffold in the iBAP. SPA exhibits 66-fold greater hydraulic permeability than the SNM along with a short (<10 μm) diffusion distance to the nearest islet. SPA also supports short-term functionality of both encapsulated human islets and stem-cell-derived enriched β-clusters in a convection-based system, demonstrated by high viability (>95%) and biphasic insulin responses to dynamic glucose stimulus. These findings suggest that the SPA scaffold will not limit nutrient delivery in a convection-based bioartificial pancreas and merits continued investigation.
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Affiliation(s)
- Rebecca Shaheen
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA
| | - Rachel E Gurlin
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA
| | - Rebecca Gologorsky
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA
| | - Charles Blaha
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA.,Silicon Kidney, San Francisco, California, USA
| | - Pujita Munnangi
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA
| | - Ana Santandreu
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA
| | - Alonso Torres
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA
| | - Phichitpol Carnese
- Diabetes Center, Department of Medicine, University of California, San Francisco, California, USA
| | - Gopika G Nair
- Diabetes Center, Department of Medicine, University of California, San Francisco, California, USA
| | - Gregory Szot
- Diabetes Center, Department of Medicine, University of California, San Francisco, California, USA
| | - William H Fissell
- Silicon Kidney, San Francisco, California, USA.,Division of Nephrology and Hypertension, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Matthias Hebrok
- Diabetes Center, Department of Medicine, University of California, San Francisco, California, USA
| | - Shuvo Roy
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California, USA.,Silicon Kidney, San Francisco, California, USA
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Connizzo BK, Grodzinsky AJ. Multiscale Poroviscoelastic Compressive Properties of Mouse Supraspinatus Tendons Are Altered in Young and Aged Mice. J Biomech Eng 2018; 140:2666618. [PMID: 29238818 PMCID: PMC5816244 DOI: 10.1115/1.4038745] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 12/04/2017] [Indexed: 02/02/2023]
Abstract
Rotator cuff disorders are one of the most common causes of shoulder pain and disability in the aging population but, unfortunately, the etiology is still unknown. One factor thought to contribute to the progression of disease is the external compression of the rotator cuff tendons, which can be significantly increased by age-related changes such as muscle weakness and poor posture. The objective of this study was to investigate the baseline compressive response of tendon and determine how this response is altered during maturation and aging. We did this by characterizing the compressive mechanical, viscoelastic, and poroelastic properties of young, mature, and aged mouse supraspinatus tendons using macroscale indentation testing and nanoscale high-frequency AFM-based rheology testing. Using these multiscale techniques, we found that aged tendons were stiffer than their mature counterparts and that both young and aged tendons exhibited increased hydraulic permeability and energy dissipation. We hypothesize that regional and age-related variations in collagen morphology and organization are likely responsible for changes in the multiscale compressive response as these structural parameters may affect fluid flow. Importantly, these results suggest a role for age-related changes in the progression of tendon degeneration, and we hypothesize that decreased ability to resist compressive loading via fluid pressurization may result in damage to the extracellular matrix (ECM) and ultimately tendon degeneration. These studies provide insight into the regional multiscale compressive response of tendons and indicate that altered compressive properties in aging tendons may be a major contributor to overall tendon degeneration.
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Affiliation(s)
- Brianne K. Connizzo
- Department of Biological Engineering,
Massachusetts Institute of Technology,
Cambridge, MA 02139
| | - Alan J. Grodzinsky
- Department of Biological Engineering,Massachusetts Institute of Technology,
Cambridge, MA 02139;
Center for Biomedical Engineering,Massachusetts Institute of Technology,
Cambridge, MA 02139;
Department of Electrical Engineeringand Computer Science,
Massachusetts Institute of Technology,
Cambridge, MA 02139;
Department of Mechanical Engineering,Massachusetts Institute of Technology,
Cambridge, MA 02139
e-mail:
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Hsu KH, Gupta K, Nayaka H, Donthi A, Kaul S, Chauhan A. Multidose Preservative Free Eyedrops by Selective Removal of Benzalkonium Chloride from Ocular Formulations. Pharm Res 2017; 34:2862-2872. [PMID: 29067592 DOI: 10.1007/s11095-017-2270-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 09/21/2017] [Indexed: 11/26/2022]
Abstract
PURPOSE About 70% of eye drops contain benzalkonium chloride (BAK) to maintain sterility. BAK is an effective preservative but it can cause irritation and toxicity. We propose to mitigate ocular toxicity without compromising sterility by incorporating a filter into an eye drop bottle to selectively remove BAK during the process of drop instillation. METHODS The filter is a packed bed of particles made from poly(2-hydroxyethyl methacrylate) (pHEMA), which is a common ophthalmic material. We showed that pHEMA particle prepared by using ethoxylated trimethylolpropane triacrylate as crosslinker can be incorporated into a modified eyedrop bottle tip to selectively remove the preservative as the formulation is squeezed out of the bottle. Hydraulic permeability of the plug is measured to determine the resistance to eye drop squeezing, and % removal of BAK and drugs are determined. RESULTS The modified tip has a hydraulic permeability of about 2 Darcy, which allows eyedrops formulations to flow through without excessive resistance. The tip is designed such that the patients can create an eyedrop of solution of 1-10 cP viscosity in 4 s with a nominal pressure. During this short contact time, the packed particles removed nearly 100% of benzalkonium chloride (BAK) from a 15 mL, 0.012% BAK solution but have only minimal impact on the concentration of contained active components. CONCLUSION Our novel design can eliminate the preservative induced toxicity from eye drops thereby impacting hundreds of millions of patients with chronic ophthalmic diseases like glaucoma and dry eyes.
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Affiliation(s)
- Kuan-Hui Hsu
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, 32611-6005, USA
| | - Karishma Gupta
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, 32611-6005, USA
| | - Harish Nayaka
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, 32611-6005, USA
| | - Aashrit Donthi
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, 32611-6005, USA
| | - Siddarth Kaul
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, 32611-6005, USA
| | - Anuj Chauhan
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, 32611-6005, USA.
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Abstract
The goal of this work is to demonstrate how the pore-size distribution of the nanocellulose-based virus-retentive filter can be tailored. The filter paper was produced using cellulose nanofibers derived from Cladophora sp. green algae using the hot-press drying at varying drying temperatures. The produced filters were characterized using scanning electron microscopy, atomic force microscopy, and N2 gas sorption analysis. Further, hydraulic permeability and retention efficiency toward surrogate 20 nm model particles (fluorescent carboxylate-modified polystyrene spheres) were assessed. It was shown that by controlling the rate of water evaporation during hot-press drying the pore-size distribution can be precisely tailored in the region between 10 and 25 nm. The mechanism of pore formation and critical parameters are discussed in detail. The results are highly valuable for development of advanced separation media, especially for virus-retentive size-exclusion filtration.
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Affiliation(s)
- Simon Gustafsson
- Division of Nanotechnology and Functional Materials, Department of Engineering Sciences, Uppsala University , Box 534 SE-75121, Uppsala, Sweden
| | - Albert Mihranyan
- Division of Nanotechnology and Functional Materials, Department of Engineering Sciences, Uppsala University , Box 534 SE-75121, Uppsala, Sweden
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Nia HT, Han L, Bozchalooi IS, Roughley P, Youcef-Toumi K, Grodzinsky AJ, Ortiz C. Aggrecan nanoscale solid-fluid interactions are a primary determinant of cartilage dynamic mechanical properties. ACS Nano 2015; 9:2614-25. [PMID: 25758717 PMCID: PMC6713486 DOI: 10.1021/nn5062707] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Poroelastic interactions between interstitial fluid and the extracellular matrix of connective tissues are critical to biological and pathophysiological functions involving solute transport, energy dissipation, self-stiffening and lubrication. However, the molecular origins of poroelasticity at the nanoscale are largely unknown. Here, the broad-spectrum dynamic nanomechanical behavior of cartilage aggrecan monolayer is revealed for the first time, including the equilibrium and instantaneous moduli and the peak in the phase angle of the complex modulus. By performing a length scale study and comparing the experimental results to theoretical predictions, we confirm that the mechanism underlying the observed dynamic nanomechanics is due to solid-fluid interactions (poroelasticity) at the molecular scale. Utilizing finite element modeling, the molecular-scale hydraulic permeability of the aggrecan assembly was quantified (kaggrecan = (4.8 ± 2.8) × 10(-15) m(4)/N·s) and found to be similar to the nanoscale hydraulic permeability of intact normal cartilage tissue but much lower than that of early diseased tissue. The mechanisms underlying aggrecan poroelasticity were further investigated by altering electrostatic interactions between the molecule's constituent glycosaminoglycan chains: electrostatic interactions dominated steric interactions in governing molecular behavior. While the hydraulic permeability of aggrecan layers does not change across species and age, aggrecan from adult human cartilage is stiffer than the aggrecan from newborn human tissue.
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Affiliation(s)
- Hadi Tavakoli Nia
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Lin Han
- School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Iman Soltani Bozchalooi
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peter Roughley
- Shriners Hospital for Children, Montreal, Quebec H3G 1A6, Canada
| | - Kamal Youcef-Toumi
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alan J. Grodzinsky
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Department of Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Address correspondence to: ,
| | - Christine Ortiz
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Address correspondence to: ,
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Fortin N, Klok HA. Glucose monitoring using a polymer brush modified polypropylene hollow fiber-based hydraulic flow sensor. ACS Appl Mater Interfaces 2015; 7:4631-40. [PMID: 25675859 DOI: 10.1021/am507927w] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Tight regulation of blood glucose levels of diabetic patients requires durable and robust continuous glucose sensing schemes. This manuscript reports the fabrication of ultrathin, phenylboronic acid (PBA) functionalized polymer brushes that swell upon glucose binding and which were integrated as the sensing interface in a new polypropylene hollow fiber (PPHF)-based hydraulic flow glucose sensor prototype. The polymer brushes were prepared via surface-initiated atom transfer radical polymerization of sodium methacrylate followed by postpolymerization modification with 3-aminophenyl boronic acid. In a first series of experiments, the glucose-response of PBA-functionalized poly(methacrylic acid) (PMAA) brushes grafted from planar silicon surfaces was investigated by quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM) experiments. The QCM-D experiments revealed a more or less linear change of the frequency shift for glucose concentrations up to ∼10 mM and demonstrated that glucose binding was completely reversible for up to seven switching cycles. The AFM experiments indicated that glucose binding was accompanied by an increase in the film thickness of the PBA functionalized PMAA brushes. The PBA functionalized PMAA brushes were subsequently grafted from the surface of PPHF membranes. The hydraulic permeability of these porous fibers depends on the thickness and swelling of the PMAA brush coating. PBA functionalized brush-coated PPHFs showed a decrease in flux upon exposure to glucose, which is consistent with swelling of the brush coating. Because they avoid the use of enzymes and do not rely on an electrochemical transduction scheme, these PPHF-based hydraulic flow sensors could represent an interesting alternative class of continuous glucose sensors.
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Affiliation(s)
- Nicolas Fortin
- Institut des Matériaux and Institut des Sciences et Ingénierie Chimiques, Laboratoire des Polymères, École Polytechnique Fédérale de Lausanne (EPFL) , Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland
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12
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Abstract
Intracranial pressure and volume vary considerably between hydrocephalic patients, and with age, health and haemodynamic status; if left untreated, intracranial pressure rises and the ventricular system expands to accommodate the excess cerebrospinal fluid, with significant morbidity and mortality. Cerebrospinal fluid shunts in use today have a high incidence of failure with shunt obstruction being the most serious. Conventional proximal shunt catheters are made from poly(dimethyl)siloxane, the walls of which are perforated with holes for the cerebrospinal fluid to pass through. The limited range of catheters, in terms of material selection and flow distribution, is responsible in large part for their poor performance. In this study, we present an alternative design of proximal catheter made of electrospun polyether urethane, and evaluate its performance in the presence of glial cells, which are responsible for shunt blockage. The viability and growth of cells on catheter materials such as poly(dimethyl)siloxane and polyurethane in the form of cast films, microfibrous mats and porous sponges were studied in the presence of proteins present in cerebrospinal fluid after 48 h and 96 h in culture. The numbers of viable cells on each substrate were comparable to untreated poly(dimethyl)siloxane, both in the presence and absence of serum proteins found in cerebrospinal fluid. A cell culture model of shunt obstruction was developed in which cells on electrospun polyether urethane catheters were subjected to flow during culture in vitro, and the degree of obstruction quantified in terms of hydraulic permeability after static and perfusion culture. The results indicate that a catheter made of electrospun polyether urethane would be able to maintain cerebrospinal fluid flow even with the presence of cells for the time period chosen for this study. These findings have implications for the design and deployment of microporous shunt catheter systems for the treatment of hydrocephalus.
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Affiliation(s)
- Supraja Suresh
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
| | - Richard A Black
- Department of Biomedical Engineering, University of Strathclyde, Glasgow, UK
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13
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Nagesh C, Shankaraiah MM, Venkatesh JS, Setty SR. Role of liquid membrane phenomenon in the anti-bacterial activity of Cefuroxime Sodium. J Basic Clin Pharm 2010; 1:77-80. [PMID: 24825969 PMCID: PMC3979183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 03/10/2010] [Accepted: 04/23/2010] [Indexed: 11/16/2022] Open
Abstract
The role of liquid membrane phenomenon has been studied in the anti bacterial activity of cephalosporins i.e. Cefuroxime sodium. In our earlier publication [1] it was reported that hydraulic permeability data obtained to demonstrate the existence of liquid membrane in series with supporting membrane generated by Cefuroxime sodium. Transport of selected permeants (glucose, PABA, glycine, and ions like Mg(++), NH4 (+), PO4 (-), Ca(++), Na(+), K(+) and Cl(-)) through liquid membrane generated by Cefuroxime sodium in series with supporting membrane has been studied. The results indicated that the liquid membrane generated by Cefuroxime sodium inhibit the transport of various essential bio-molecules and permeants in to the cell. This modification in permeability of different permeants in the presence of the liquid membranes is likely to play significant role in the biological actions of Cefuroxime sodium. The anti-bacterial activity of Cefuroxime sodium further confirmed that the generation of liquid membrane by Cefuroxime sodium is also contributing for the antibacterial activity of them.
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Affiliation(s)
- C. Nagesh
- Galen Laboratory, Salipur, S. C. S. College of Pharmacy, Harapanahalli - 583131, Karnataka, India
| | - M. M. Shankaraiah
- Galen Laboratory, Salipur, S. C. S. College of Pharmacy, Harapanahalli - 583131, Karnataka, India
| | - J. S. Venkatesh
- Galen Laboratory, Salipur, S. C. S. College of Pharmacy, Harapanahalli - 583131, Karnataka, India
| | - S. Ramachandra Setty
- College of Clinical Pharmacy, King Faisal University, AL AHSA, 31982, KSA,Corresponding author: E-mail:
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