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Enhanced microscopic dynamics in mucus gels under a mechanical load in the linear viscoelastic regime. Proc Natl Acad Sci U S A 2021; 118:2103995118. [PMID: 34728565 DOI: 10.1073/pnas.2103995118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2021] [Indexed: 12/24/2022] Open
Abstract
Mucus is a biological gel covering the surface of several tissues and ensuring key biological functions, including as a protective barrier against dehydration, pathogen penetration, or gastric acids. Mucus biological functioning requires a finely tuned balance between solid-like and fluid-like mechanical response, ensured by reversible bonds between mucins, the glycoproteins that form the gel. In living organisms, mucus is subject to various kinds of mechanical stresses, e.g., due to osmosis, bacterial penetration, coughing, and gastric peristalsis. However, our knowledge of the effects of stress on mucus is still rudimentary and mostly limited to macroscopic rheological measurements, with no insight into the relevant microscopic mechanisms. Here, we run mechanical tests simultaneously to measurements of the microscopic dynamics of pig gastric mucus. Strikingly, we find that a modest shear stress, within the macroscopic rheological linear regime, dramatically enhances mucus reorganization at the microscopic level, as signaled by a transient acceleration of the microscopic dynamics, by up to 2 orders of magnitude. We rationalize these findings by proposing a simple, yet general, model for the dynamics of physical gels under strain and validate its assumptions through numerical simulations of spring networks. These results shed light on the rearrangement dynamics of mucus at the microscopic scale, with potential implications in phenomena ranging from mucus clearance to bacterial and drug penetration.
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Elastic and Dynamic Heterogeneity in Aging Alginate Gels. Polymers (Basel) 2021; 13:polym13213618. [PMID: 34771174 PMCID: PMC8587450 DOI: 10.3390/polym13213618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 11/16/2022] Open
Abstract
Anomalous aging in soft glassy materials has generated a great deal of interest because of some intriguing features of the underlying relaxation process, including the emergence of "ultra-long-range" dynamical correlations. An intriguing possibility is that such a huge correlation length is reflected in detectable ensemble fluctuations of the macroscopic material properties. We tackle this issue by performing replicated mechanical and dynamic light scattering (DLS) experiments on alginate gels, which recently emerged as a good model-system of anomalous aging. Here we show that some of the monitored quantities display wide variability, including large fluctuations in the stress relaxation and the occasional presence of two-step decay in the DLS decorrelation functions. By quantifying elastic fluctuation through the standard deviation of the elastic modulus and dynamic heterogeneities through the dynamic susceptibility, we find that both quantities do increase with the gel age over a comparable range. Our results suggest that large elastic fluctuations are closely related to ultra-long-range dynamical correlation, and therefore may be a general feature of anomalous aging in gels.
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Richter R, Kamal M, García-Rivera MA, Kaspar J, Junk M, Elgaher WA, Srikakulam SK, Gress A, Beckmann A, Grißmer A, Meier C, Vielhaber M, Kalinina O, Hirsch AK, Hartmann RW, Brönstrup M, Schneider-Daum N, Lehr CM. A hydrogel-based in vitro assay for the fast prediction of antibiotic accumulation in Gram-negative bacteria. Mater Today Bio 2020; 8:100084. [PMID: 33313504 PMCID: PMC7720078 DOI: 10.1016/j.mtbio.2020.100084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/16/2020] [Accepted: 10/20/2020] [Indexed: 11/30/2022] Open
Abstract
The pipeline of antibiotics has been for decades on an alarmingly low level. Considering the steadily emerging antibiotic resistance, novel tools are needed for early and easy identification of effective anti-infective compounds. In Gram-negative bacteria, the uptake of anti-infectives is especially limited. We here present a surprisingly simple in vitro model of the Gram-negative bacterial envelope, based on 20% (w/v) potato starch gel, printed on polycarbonate 96-well filter membranes. Rapid permeability measurements across this polysaccharide hydrogel allowed to correctly predict either high or low accumulation for all 16 tested anti-infectives in living Escherichia coli. Freeze-fracture TEM supports that the macromolecular network structure of the starch hydrogel may represent a useful surrogate of the Gram-negative bacterial envelope. A random forest analysis of in vitro data revealed molecular mass, minimum projection area, and rigidity as the most critical physicochemical parameters for hydrogel permeability, in agreement with reported structural features needed for uptake into Gram-negative bacteria. Correlating our dataset of 27 antibiotics from different structural classes to reported MIC values of nine clinically relevant pathogens allowed to distinguish active from nonactive compounds based on their low in vitro permeability specifically for Gram-negatives. The model may help to identify poorly permeable antimicrobial candidates before testing them on living bacteria.
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Affiliation(s)
- Robert Richter
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
| | - Mohamed.A.M. Kamal
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Mariel A. García-Rivera
- Department of Chemical Biology, Helmholtz Centre for Infection Research (HZI), 38124 Braunschweig, Germany
| | - Jerome Kaspar
- Institute of Engineering Design, Saarland University, 66123 Saarbrücken, Germany
| | - Maximilian Junk
- Institute of Engineering Design, Saarland University, 66123 Saarbrücken, Germany
| | - Walid A.M. Elgaher
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Sanjay Kumar Srikakulam
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Alexander Gress
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Anja Beckmann
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Alexander Grißmer
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Carola Meier
- Department of Anatomy and Cell Biology, Saarland University, 66421 Homburg, Germany
| | - Michael Vielhaber
- Institute of Engineering Design, Saarland University, 66123 Saarbrücken, Germany
| | - Olga Kalinina
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Medical Faculty, Saarland University, 66421 Homburg, Germany
| | - Anna K.H. Hirsch
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
| | - Rolf W. Hartmann
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Mark Brönstrup
- Department of Chemical Biology, Helmholtz Centre for Infection Research (HZI), 38124 Braunschweig, Germany
- German Centre for Infection Research (DZIF), 38124 Braunschweig, Germany
| | - Nicole Schneider-Daum
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
| | - Claus-Michael Lehr
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) – Helmholtz Centre for Infection Research (HZI), 66123 Saarbrücken, Germany
- Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany
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Pastore R, Siviello C, Greco F, Larobina D. Anomalous Aging and Stress Relaxation in Macromolecular Physical Gels: The Case of Strontium Alginate. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b01953] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raffaele Pastore
- Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale, Università di Napoli Federico II, P.le Tecchio 80, 80125 Napoli, Italy
| | - Ciro Siviello
- Institute for Polymers, Composites, and Biomaterials, National Research Council of Italy, P.le E. Fermi 1, 80055 Portici, NA, Italy
| | - Francesco Greco
- Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale, Università di Napoli Federico II, P.le Tecchio 80, 80125 Napoli, Italy
| | - Domenico Larobina
- Institute for Polymers, Composites, and Biomaterials, National Research Council of Italy, P.le E. Fermi 1, 80055 Portici, NA, Italy
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Verheyen CA, Morales L, Sussman J, Paunovska K, Manzoli V, Ziebarth NM, Tomei AA. Characterization of Polyethylene Glycol-Reinforced Alginate Microcapsules for Mechanically Stable Cell Immunoisolation. MACROMOLECULAR MATERIALS AND ENGINEERING 2019; 304:1800679. [PMID: 31929732 PMCID: PMC6953757 DOI: 10.1002/mame.201800679] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Indexed: 06/02/2023]
Abstract
Islet transplantation within mechanically stable microcapsules offers the promise of long-term diabetes reversal without chronic immunosuppression. Reinforcing the ionically gelled network of alginate (ALG) hydrogels with covalently linked polyethylene glycol (PEG) may create hybrid structures with desirable mechanical properties. This report describes the fabrication of hybrid PEG-ALG interpenetrating polymer networks and the investigation of microcapsule swelling, surface modulus, rheology, compression, and permeability. It is demonstrated that hybrid networks are more resistant to bulk swelling and compressive deformation and display improved shape recovery and long-term resilience. Interestingly, it is shown that PEG-ALG networks behave like ALG during microscale surface deformation and small amplitude shear while exhibiting similar permeability properties. The results from this report's in vitro characterization are interpreted according to viscoelastic polymer theory and provide new insight into hybrid hydrogel mechanical behavior. This new understanding of PEG-ALG mechanical performance is then linked to previous work that demonstrated the success of hybrid polymer immunoisolation devices in vivo.
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Affiliation(s)
- Connor A Verheyen
- Diabetes Research Institute, 1450 NW 10th Avenue, Miami, FL 33136, USA
| | - Laura Morales
- Diabetes Research Institute, 1450 NW 10th Avenue, Miami, FL 33136, USA
| | - Joshua Sussman
- Diabetes Research Institute, 1450 NW 10th Avenue, Miami, FL 33136, USA
| | - Kalina Paunovska
- Diabetes Research Institute, 1450 NW 10th Avenue, Miami, FL 33136, USA
| | - Vita Manzoli
- Diabetes Research Institute, 1450 NW 10th Avenue, Miami, FL 33136, USA
| | - Noel M Ziebarth
- Department of Biomedical Engineering, University of Miami, 1251 Memorial Drive, Coral Gables, FL-33146, USA
| | - Alice A Tomei
- Diabetes Research Institute, 1450 NW 10th Avenue, Miami, FL 33136, USA
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Jiaojiao X, Bin Z, Gangbin Z, Ping W, Zhenjiang L. Quick separation and enzymatic performance improvement of lipase by ionic liquid-modified Fe 3O 4 carrier immobilization. Bioprocess Biosyst Eng 2018; 41:739-748. [PMID: 29411098 DOI: 10.1007/s00449-018-1907-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/31/2018] [Indexed: 01/19/2023]
Abstract
To promote the activity and stability of immobilized porcine pancreatic lipase (PPL), novel carrier was combined with special immobilization method. Enzymatic activity was enhanced after immobilized onto ionic liquid modified magnetic Fe3O4 by electrostatic adsorption. Activity of immobilized enzyme (PPL-IM/BF4-Fe3O4@CA) reached 596 U/g PPL. Through the combination of electrostatic adsorption and embedding immobilization methods, we improve binding force between the carrier and enzyme, and further enhance the efficiency and stability of immobilized enzyme. The activity of PPL-IM/BF4-Fe3O4@CA after repeated third use was 78%. After storage at room temperature for 5 days, the residual activity was 89%. Enzymatic properties and catalytic kinetics of immobilized enzymes were studied, and the effect mechanism of ionic liquid modified Fe3O4 on PPL was revealed. The effect of ionic liquid on the carrier structure was investigated by characterization of XRD, FT-IR, SEM and TG. The mechanism and enzymatic properties of immobilized PPL via electrostatic adsorption and embedding were analyzed. A novel and efficient immobilized PPL was developed.
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Affiliation(s)
- Xia Jiaojiao
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Zhenjiang, 212013, China
| | - Zou Bin
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Zhenjiang, 212013, China.
| | - Zhu Gangbin
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Zhenjiang, 212013, China
| | - Wei Ping
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Zhenjiang, 212013, China
| | - Liu Zhenjiang
- School of Food and Biological Engineering, Jiangsu University, No. 301 Xuefu Road, Zhenjiang, 212013, China
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