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V B, Magesh V, Harikrishnan P. Effect of cortical bone thickness on shear stress and force in orthodontic miniscrew-bone interface - A finite element analysis. Biomed Phys Eng Express 2024; 10:055013. [PMID: 38986445 DOI: 10.1088/2057-1976/ad6160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 07/10/2024] [Indexed: 07/12/2024]
Abstract
Miniscrews are widely used in orthodontics as an anchorage device while aligning teeth. Shear stress in the miniscrew-bone interface is an important factor when the miniscrew makes contact with the bone. The objective of this study was to analyze the shear stress and force in the screw-bone interface for varying Cortical Bone Thickness (CBT) using Finite Element Analysis (FEA). Varying CBT of 1.09 mm (1.09CBT) and 2.66 mm (2.66CBT) with miniscrews of Ø1.2 mm, 10 mm length (T1), Ø1.2 mm, 6 mm length (T2) and Ø1.6 mm, 8 mm length (T3) were analyzed. Six Finite Element (FE) models were developed with cortical, cancellous bone, miniscrews and gingiva as a prism. A deflection of 0.1 mm was applied on the neck of the miniscrews at 0°, +30° and -30° angles. The shear stress and force in the screw-bone interface were assessed. The results showed that the CBT affects the shear stress and force in the screw-bone interface region in addition to the screw dimensions and deflection angulations. T1 screw generated lesser shear stress in 1.09CBTand 2.66CBTcompared to T2 and T3 screws. Higher CBT is preferred for better primary stability in shear aspect. Clinically applied forces of 200 gms to 300 gms to an anchorage device induces shear stress in the miniscrew-bone interface region might cause stress shielding. Thus, clinicians need to consider the effect of varying CBT and the size of the miniscrews for the stability, reduced stress shielding and better anchorage during orthodontic treatment.
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Affiliation(s)
- Balamurali V
- Department of Mechanical Engineering, College of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur, Chennai - 603203, Tamil Nadu, India
| | - Varadaraju Magesh
- Department of Mechanical Engineering, College of Engineering and Technology, SRM Institute of Science and Technology, Kattankulathur, Chennai - 603203, Tamil Nadu, India
| | - Pandurangan Harikrishnan
- Craniofacial Orthodontist and Oral Surgeon, Teeth 'N' Jaws Center, No. 23 & 25, 1st Cross Street, Lake Area, Nungambakkam, Chennai - 600034, Tamil Nadu, India
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2
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Zhang C, Zeng C, Wang Z, Zeng T, Wang Y. Optimization of stress distribution of bone-implant interface (BII). BIOMATERIALS ADVANCES 2023; 147:213342. [PMID: 36841109 DOI: 10.1016/j.bioadv.2023.213342] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 02/03/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023]
Abstract
Many studies have found that the threshold of occlusal force tolerated by titanium-based implants is significantly lower than that of natural teeth due to differences in biomechanical mechanisms. Therefore, implants are considered to be susceptible to occlusal trauma. In clinical practice, many implants have shown satisfactory biocompatibility, but the balance between biomechanics and biofunction remains a huge clinical challenge. This paper comprehensively analyzes and summarizes various stress distribution optimization methods to explore strategies for improving the resistance of the implants to adverse stress. Improving stress resistance reduces occlusal trauma and shortens the gap between implants and natural teeth in occlusal function. The study found that: 1) specific implant-abutment connection design can change the force transfer efficiency and force conduction direction of the load at the BII; 2) reasonable implant surface structure and morphological character design can promote osseointegration, maintain alveolar bone height, and reduce the maximum effective stress at the BII; and 3) the elastic modulus of implants matched to surrounding bone tissue can reduce the stress shielding, resulting in a more uniform stress distribution at the BII. This study concluded that the core BII stress distribution optimization lies in increasing the stress distribution area and reducing the local stress peak value at the BII. This improves the biomechanical adaptability of the implants, increasing their long-term survival rate.
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Affiliation(s)
- Chunyu Zhang
- Xiangya Stomatological Hospital, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Xiangya School of Stomatology, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Hunan 3D Printing Engineering Research Center of Oral Care, No. 64 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China.
| | - Chunyu Zeng
- Xiangya Stomatological Hospital, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Xiangya School of Stomatology, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Hunan 3D Printing Engineering Research Center of Oral Care, No. 64 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China
| | - Zhefu Wang
- Xiangya Stomatological Hospital, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Xiangya School of Stomatology, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Hunan 3D Printing Engineering Research Center of Oral Care, No. 64 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China
| | - Ting Zeng
- Xiangya Stomatological Hospital, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Xiangya School of Stomatology, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Hunan 3D Printing Engineering Research Center of Oral Care, No. 64 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China
| | - Yuehong Wang
- Xiangya Stomatological Hospital, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Xiangya School of Stomatology, Central South University, No. 72 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China; Hunan 3D Printing Engineering Research Center of Oral Care, No. 64 Xiangya Street, Kaifu District, Changsha, 410008, Hunan, China.
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Lee KH, Park SJ, Choi S, Uh Y, Park JY, Han KH. The Influence of Urinary Catheter Materials on Forming Biofilms of Microorganisms. ACTA ACUST UNITED AC 2017. [DOI: 10.4167/jbv.2017.47.1.32] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Kyoung-Ho Lee
- Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Su Jung Park
- Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - SunJu Choi
- Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Young Uh
- Department of Laboratory Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Joo Young Park
- Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Kyoung-Hee Han
- Department of Obstetrics and Gynecology, Yonsei University Wonju College of Medicine, Wonju, Korea
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Battiston K, Ouyang B, Honarparvar E, Qian J, Labow R, Simmons C, Santerre J. Interaction of a block-co-polymeric biomaterial with immunoglobulin G modulates human monocytes towards a non-inflammatory phenotype. Acta Biomater 2015; 24:35-43. [PMID: 26074158 DOI: 10.1016/j.actbio.2015.06.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 05/25/2015] [Accepted: 06/04/2015] [Indexed: 01/22/2023]
Abstract
Monocyte interactions with implanted biomaterials can contribute significantly to the ability of a biomaterial to support tissue integration and wound healing, as opposed to a chronic pro-inflammatory foreign body reaction, provided the materials are designed to do so. However, there are few biomaterials available designed to regulate immune cell response with the intention of reducing the pro-inflammatory activation state. Material chemistry is a powerful tool for regulating protein and cell interactions that can be incorporated into surfaces while maintaining desired mechanical properties. The aspects of material chemistry that can support monocyte activation away from a pro-inflammatory state are still poorly understood. Protein adsorption is a key initial event that transforms the surface of a biomedical device into a biological substrate that will govern subsequent cellular interactions. In this study, the chemistry of degradable block polyurethanes, termed degradable polar hydrophobic ionic (D-PHI) polyurethanes, were studied for their unique interactions with bound immunoglobulin G (IgG), a pro-inflammatory protein that supports monocyte-biomaterial interactions. The specific immunological active sites of the polyurethane-adsorbed protein were compared with IgG's adsorbed state on a homopolymeric material with surface chemistry conducive to cell interactions, e.g. tissue culture polystyrene (TCPS). IgG-coated TCPS supported sustained monocyte adhesion and enhanced monocyte spreading, effects not observed with IgG-coated PU. The degradable PU was subsequently shown to reduce the number of exposed IgG-Fab sites following pre-adsorption vs. IgG adsorbed to TCPS, with antibody inhibition experiments demonstrating that Fab-site exposure appears to dominate monocyte-biomaterial interactions. Minor changes in chemical segments within the PU molecular chains were subsequently investigated for their influence on directing IgG interactions towards reducing pro-inflammatory activity. A reduction in chemical heterogeneity within the PU, without significant differences in other material properties known to regulate monocyte response, was shown to increase Fab exposure and subsequently led to monocyte interactions similar to those observed for IgG-coated TCPS. These results infer that reduced IgG-Fab site exposure can be directed by material chemistry to attenuate pro-inflammatory monocyte interactions with biomaterial surfaces, and identify the chemical features of polymeric biomaterial design responsible for this process. STATEMENT OF SIGNIFICANCE There is currently limited understanding of material design features that can regulate protein-material interactions in order to prevent adverse inflammatory responses to implanted biomaterials. In this paper, monocyte interactions with biomaterials (specifically a block co-polymeric degradable polyurethane [D-PHI] and tissue culture polystyrene [TCPS]) were investigated as a function of their interactions with adsorbed immunoglobulin G (IgG). D-PHI was shown to attenuate IgG-induced monocyte retention and spreading by reducing IgG-Fab site exposure upon adsorption relative to TCPS. Aspects of D-PHI chemistry important in regulating Fab site exposure were determined. This study thus identifies features of biomaterials, using D-PHI as a case study, which can contribute to the development of new immunomodulatory biomaterial design.
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Harake RS, Ding Y, Brown JD, Pan T. Design, Fabrication, and In Vitro Testing of an Anti-biofouling Glaucoma Micro-shunt. Ann Biomed Eng 2015; 43:2394-405. [PMID: 25821113 DOI: 10.1007/s10439-015-1309-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/21/2015] [Indexed: 11/30/2022]
Abstract
Glaucoma, one of the leading causes of irreversible blindness, is a progressive neurodegenerative disease. Chronic elevated intraocular pressure (IOP), a prime risk factor for glaucoma, can be treated by aqueous shunts, implantable devices, which reduce IOP in glaucoma patients by providing alternative aqueous outflow pathways. Although initially effective at delaying glaucoma progression, contemporary aqueous shunts often lead to numerous complications and only 50% of implanted devices remain functional after 5 years. In this work, we introduce a novel micro-device which provides an innovative platform for IOP reduction in glaucoma patients. The device design features an array of parallel micro-channels to provide precision aqueous outflow resistance control. Additionally, the device's microfluidic channels are composed of a unique combination of polyethylene glycol materials in order to provide enhanced biocompatibility and resistance to problematic channel clogging from biofouling of aqueous proteins. The microfabrication process employed to produce the devices results in additional advantages such as enhanced device uniformity and increased manufacturing throughput. Surface characterization experimental results show the device's surfaces exhibit significantly less non-specific protein adsorption compared to traditional implant materials. Results of in vitro flow experiments verify the device's ability to provide aqueous resistance control, continuous long-term stability through 10-day protein flow testing, and safety from risk of infection due to bacterial ingression.
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Affiliation(s)
- Ryan S Harake
- Micro-Nano Innovations (MiNI) Laboratory, Department of Biomedical Engineering, University of California, Davis, USA
| | - Yuzhe Ding
- Micro-Nano Innovations (MiNI) Laboratory, Department of Biomedical Engineering, University of California, Davis, USA
| | | | - Tingrui Pan
- Micro-Nano Innovations (MiNI) Laboratory, Department of Biomedical Engineering, University of California, Davis, USA.
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Ma Y, Chen M, Jones JE, Ritts AC, Yu Q, Sun H. Inhibition of Staphylococcus epidermidis biofilm by trimethylsilane plasma coating. Antimicrob Agents Chemother 2012; 56:5923-37. [PMID: 22964248 PMCID: PMC3486604 DOI: 10.1128/aac.01739-12] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 08/31/2012] [Indexed: 12/14/2022] Open
Abstract
Biofilm formation on implantable medical devices is a major impediment to the treatment of nosocomial infections and promotes local progressive tissue destruction. Staphylococcus epidermidis infections are the leading cause of biofilm formation on indwelling devices. Bacteria in biofilms are highly resistant to antibiotic treatment, which in combination with the increasing prevalence of antibiotic resistance among human pathogens further complicates treatment of biofilm-related device infections. We have developed a novel plasma coating technology. Trimethylsilane (TMS) was used as a monomer to coat the surfaces of 316L stainless steel and grade 5 titanium alloy, which are widely used in implantable medical devices. The results of biofilm assays demonstrated that this TMS coating markedly decreased S. epidermidis biofilm formation by inhibiting the attachment of bacterial cells to the TMS-coated surfaces during the early phase of biofilm development. We also discovered that bacterial cells on the TMS-coated surfaces were more susceptible to antibiotic treatment than their counterparts in biofilms on uncoated surfaces. These findings suggested that TMS coating could result in a surface that is resistant to biofilm development and also in a bacterial community that is more sensitive to antibiotic therapy than typical biofilms.
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Affiliation(s)
- Yibao Ma
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Missouri, Columbia, Missouri, USA
| | - Meng Chen
- Nanova, Inc., Columbia, Missouri, USA
| | - John E. Jones
- Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri, USA
| | | | - Qingsong Yu
- Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri, USA
| | - Hongmin Sun
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Missouri, Columbia, Missouri, USA
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7
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Chang X, Gorbet M. The effect of shear on in vitro platelet and leukocyte material-induced activation. J Biomater Appl 2012; 28:407-15. [DOI: 10.1177/0885328212454689] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The failure to understand the mechanisms of biomaterial-associated thrombosis prevents us from improving the blood compatibility of stents and mechanical heart valves. Blood-material interactions trigger a complex series of events and anticoagulant and anti-platelet therapies are needed to reduce the risks of thrombotic complications with most cardiovascular materials. While material interaction with platelets has been widely studied, little is currently known on material-induced leukocyte activation in the presence of shear. In vitro experiments were performed to assess the effect of flow on blood cell activation induced by medical grade metals, ST316L and TiAl6V4. Blood was circulated in flow chambers preloaded with or without metal wires at shear rates of 100, 500, and 1500 s−1. Platelet and leukocyte activation, leukocyte-platelet aggregation, and tissue factor expression on monocytes were measured by flow cytometry. Metal surfaces were characterized by scanning electron microscopy. Under physiological shear rates, no significant platelet microparticle formation was observed. However, significant CD11b up-regulation, leukocyte-platelet aggregates, and tissue factor expression were observed at 100 s−1. As shear rate increased to 1500 s−1, leukocyte activation reduced to control values. TiAl6V4-induced leukocyte activation was generally lower than that of ST316L. Adhesion significantly decreased with increasing shear rate to 1500 s−1. In blood, increase within physiological shear rates led to a significant reduction in in vitro material-induced leukocyte activation, suggesting that difference between material biocompatibility may be better identified at low shear rates or under pathological shear conditions.
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Affiliation(s)
- Xiaojian Chang
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON, Canada
| | - Maud Gorbet
- Department of Systems Design Engineering, University of Waterloo, Waterloo, ON, Canada
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8
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Patel JD, Colton E, Ebert M, Anderson JM. Gene expression duringS. epidermidisbiofilm formation on biomaterials. J Biomed Mater Res A 2012; 100:2863-9. [DOI: 10.1002/jbm.a.34221] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 11/09/2022]
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9
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Khandwekar A, Rho CK. Modulation of cellular responses on engineered polyurethane implants. J Biomed Mater Res A 2012; 100:2211-22. [PMID: 22492665 DOI: 10.1002/jbm.a.34146] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 01/30/2012] [Accepted: 02/09/2012] [Indexed: 12/18/2022]
Abstract
An in vivo rat cage implant system was used to study the effect of polyurethane surface chemistries on protein adsorption, macrophage adhesion, foreign-body giant cell formation (FBGCs), cellular apoptosis, and cytokine response. Polyurethanes with zwitterionic, anionic, and cationic chemistries were developed. The changes in the surface topography of the materials were determined using atomic force microscopy and the wettability by dynamic contact angle measurements. The in vitro protein adsorption studies revealed higher protein adsorption on cationic surfaces when compared with the base, while adsorption was significantly reduced on zwitterionic (**p < 0.01) and anionic (*p < 0.05) polyurethanes. Analysis of the exudates surrounding the materials revealed no differences between surfaces in the types or levels of cells present. Conversely, the proportion of adherent cells undergoing apoptosis, as determined by annexin V-FITC staining, increased significantly on anionic followed by zwitterionic surfaces (60 + 5.0 and 38 + 3.7%) when compared with the base. Additionally, zwitterionic and anionic substrates provided decreased rates of macrophage adhesion and fusion into FBGCs, whereas cationic surfaces promoted macrophage adhesion and FBGC formation. Visualization of the F-actin cytoskeleton by Alexa Fluor 488 phalloidin showed a significant delay in the cytoskeletal fusion response on zwitterionic and the anionic surfaces. The real-time polymerase chain reaction (PCR) analysis of proinflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-10) and pro-wound healing cytokines (IL-4 and TGF-β) revealed differential cytokine responses. Cationic substrates that triggered stimulation of TNF-α and IL-4 were associated with more spread cells and higher FBGCs, whereas zwitterionic and anionic substrates that suppressed these cytokines levels were associated with less spread cells and few FBGCs. These studies have revealed that zwitterionic and anionic polyurethane surface chemistries can not only reduce nonspecific adhesion, fusion, and inflammatory events but also effectively promote cellular apoptosis in vivo.
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Affiliation(s)
- Anand Khandwekar
- Department of Bioengineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
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10
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Salvagnini C, Roback A, Momtaz M, Pourcelle V, Marchand-Brynaert J. Surface functionalization of a poly(butylene terephthalate) (PBT) melt-blown filtration membrane by wet chemistry and photo-grafting. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2012. [DOI: 10.1163/156856207794761934] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Claudio Salvagnini
- a Unité de Chimie Organique et Médicinale, Université catholique de Louvain, Bâtiment Lavoisier, place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
| | - Alexandre Roback
- b Unité de Chimie Organique et Médicinale, Université catholique de Louvain, Bâtiment Lavoisier, place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
| | - Maryam Momtaz
- c Unité de Chimie Organique et Médicinale, Université catholique de Louvain, Bâtiment Lavoisier, place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
| | - Vincent Pourcelle
- d Unité de Chimie Organique et Médicinale, Université catholique de Louvain, Bâtiment Lavoisier, place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
| | - Jacqueline Marchand-Brynaert
- e Unité de Chimie Organique et Médicinale, Université catholique de Louvain, Bâtiment Lavoisier, place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium
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11
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Jones JA, Dadsetan M, Collier TO, Ebert M, Stokes KS, Ward RS, Hiltner PA, Anderson JM. Macrophage behavior on surface-modified polyurethanes. JOURNAL OF BIOMATERIALS SCIENCE-POLYMER EDITION 2012; 15:567-84. [PMID: 15264659 DOI: 10.1163/156856204323046843] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Adherent macrophages and foreign body giant cells (FBGCs) are known to release degradative molecules that can be detrimental to the long-term biostability of polyurethanes. The modification of polyurethanes using surface modifying endgroups (SMEs) and/or the incorporation of silicone into the polyurethane soft segments may alter macrophage adhesion, fusion and apoptosis resulting in improved long-term biostability. An in vitro study of macrophage adhesion, fusion and apoptosis was performed on polyurethanes modified with fluorocarbon SMEs, polyethylene oxide (PEO) SMEs, or poly(dimethylsiloxane) (PDMS) co-soft segment and SMEs. The fluorocarbon SME and PEO SME modifications were shown to have no effect on macrophage adhesion and activity, while silicone modification had varied effects. Macrophages were capable of adapting to the surface and adhering in a similar manner to the silicone-modified and unmodified polyurethanes. In the absence of IL-4, macrophage fusion was comparable on the modified and unmodified polyurethanes, while macrophage apoptosis was promoted on the silicone modified surfaces. In contrast, when exposed to IL-4, a cytokine known to induce FBGC formation, silicone modification resulted in more macrophage fusion to form foreign body giant cells. In conclusion, fluorocarbon SME and PEO SME modification does not affect macrophage adhesion, fusion and apoptosis, while silicone modification is capable of mediating macrophage fusion and apoptosis. Silicone modification may be utilized to direct the fate of adherent macrophages towards FBGC formation or cell death through apoptosis.
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Affiliation(s)
- Jacqueline A Jones
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, USA
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Wan PJ, Tan DS, Li ZS, Zhang XQ, Li JH, Tan H. Biomimetic surface preparation of inert polymer films via grafting long monoalkyl chain phosphatidylcholine. CHINESE JOURNAL OF POLYMER SCIENCE 2011. [DOI: 10.1007/s10118-012-1111-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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13
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Clauss M, Trampuz A, Borens O, Bohner M, Ilchmann T. Biofilm formation on bone grafts and bone graft substitutes: comparison of different materials by a standard in vitro test and microcalorimetry. Acta Biomater 2010; 6:3791-7. [PMID: 20226886 DOI: 10.1016/j.actbio.2010.03.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 02/14/2010] [Accepted: 03/05/2010] [Indexed: 02/03/2023]
Abstract
We analyzed the initial adhesion and biofilm formation of Staphylococcus aureus (ATCC 29213) and S. epidermidis RP62A (ATCC 35984) on various bone grafts and bone graft substitutes under standardized in vitro conditions. In parallel, microcalorimetry was evaluated as a real-time microbiological assay in the investigation of biofilm formation and material science research. The materials beta-tricalcium phosphate (beta-TCP), processed human spongiosa (Tutoplast) and poly(methyl methacrylate) (PMMA) were investigated and compared with polyethylene (PE). Bacterial counts (log(10) cfu per sample) were highest on beta-TCP (S. aureus 7.67 +/- 0.17; S. epidermidis 8.14 +/- 0.05) while bacterial density (log(10) cfu per surface) was highest on PMMA (S. aureus 6.12 +/- 0.2, S. epidermidis 7.65 +/- 0.13). Detection time for S. aureus biofilms was shorter for the porous materials (beta-TCP and processed human spongiosa, p < 0.001) compared to the smooth materials (PMMA and PE), with no differences between beta-TCP and processed human spongiosa (p > 0.05) or PMMA and PE (p > 0.05). In contrast, for S. epidermidis biofilms the detection time was different (p < 0.001) between all materials except between processed human spongiosa and PE (p > 0.05). The quantitative analysis by quantitative culture after washing and sonication of the material demonstrated the importance of monitoring factors like specific surface or porosity of the test materials. Isothermal microcalorimetry proved to be a suitable tool for an accurate, non-invasive and real-time microbiological assay, allowing the detection of bacterial biomass without removing the biofilm from the surface.
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Affiliation(s)
- Martin Clauss
- Department of Orthopedic Surgery, Kantonsspital Liestal, Liestal, Switzerland.
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14
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Preparation and characterization of nonfouling polymer brushes on poly(ethylene terephthalate) film surfaces. Colloids Surf B Biointerfaces 2010; 78:343-50. [DOI: 10.1016/j.colsurfb.2010.03.027] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 02/09/2010] [Accepted: 03/22/2010] [Indexed: 12/27/2022]
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15
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Somorjai GA, Frei H, Park JY. Advancing the Frontiers in Nanocatalysis, Biointerfaces, and Renewable Energy Conversion by Innovations of Surface Techniques. J Am Chem Soc 2009; 131:16589-605. [DOI: 10.1021/ja9061954] [Citation(s) in RCA: 459] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabor A. Somorjai
- Department of Chemistry and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460
| | - Heinz Frei
- Department of Chemistry and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460
| | - Jeong Y. Park
- Department of Chemistry and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460
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Mukherjee PK, Chand DV, Chandra J, Anderson JM, Ghannoum MA. Shear stress modulates the thickness and architecture of Candida albicans biofilms in a phase-dependent manner. Mycoses 2008; 52:440-6. [PMID: 19076284 DOI: 10.1111/j.1439-0507.2008.01632.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Biofilm formation plays an integral role in catheter-associated bloodstream infections caused by Candida albicans. Biofilms formed on catheters placed intravenously are exposed to shear stress caused by blood flow. In this study, we investigated whether shear stress affects the ability of C. albicans to form biofilms. Candida biofilms were formed on catheter discs and exposed to physiological levels of shear stress using a rotating disc system (RDS). Control biofilms were grown under conditions of no flow. Tetrazolium (XTT) assay and dry weight (DW) measurements were used to quantify metabolic activity and biofilm mass respectively. Confocal scanning laser microscopy (CSLM) was used to evaluate architecture and biofilm thickness. After 90 min, cells attached under no-flow exhibited significantly greater XTT activity and DW than those under shear. However, by 24 h, biofilms formed under both conditions had similar XTT activities and DW. Interestingly, thickness of biofilms formed under no-flow was significantly greater after 24 h than of those formed under shear stress, demonstrating that shear exposure results in thinner, but denser biofilms. These studies suggest that biofilm architecture is modulated by shear in a phase-dependent manner.
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Affiliation(s)
- Pranab K Mukherjee
- Center for Medical Mycology, Department of Dermatology, University Hospitals of Cleveland and Case Western Reserve University, OH 44106-5028, USA
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17
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Xie X, Tan H, Li J, Zhong Y. Synthesis and characterization of fluorocarbon chain end-capped poly(carbonate urethane)s as biomaterials: A novel bilayered surface structure. J Biomed Mater Res A 2008; 84:30-43. [PMID: 17600322 DOI: 10.1002/jbm.a.31288] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Poly(carbonate urethane)s (PCUs) are usually considered as biostable elastomers for long-term implantation. However, their hydrolytic stability is still questionable. The biodegradation appears to be initiated by oxidative and hydrolytic substances released by inflammatory cells. Therefore, the biostability of polyurethane might be improved with control of surface structure to reduce inflammatory response. A new type of PCUs end-capped with perfluoro chains was synthesized to explore a new avenue. A fluorinated alcohol, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-1-octanol (PDFOL), was end-capped to the backbones of PCUs by reaction of the --OH in PDFOL with the --NCO end groups in PCU backbones. Contact angle measurement, X-ray photoelectron spectroscopy, atomic force microscopy, and attenuated total reflectance-Fourier transform infrared spectroscopy were used to examine their surface structure and properties. Elemental analysis, gel permeation chromatography, differential scanning calorimetry, and tensile testing were used to assess bulk chemistry and properties. The fluorocarbon end-capped poly (carbonate urethane)s (FPCUs) maintained the high mechanical properties (about 40 MPa tensile strength) and typical microphase separation structure of polyurethane elastomers. Results from surface analyses revealed the presence of a double-layered structure at the surfaces of the FPCUs. The first one was composed of fluorocarbon tails rising up on the uppermost layer and the second one made up of hard-segments. This novel bilayered surface structure could protect the weak carbonate linkages in soft segments, and consequently, may potentially increase the biostability of this kind of polyurethanes.
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Affiliation(s)
- Xingyi Xie
- Department of Biomaterials and Artificial Organs, College of Polymer Science and Engineering, Sichuan University, Chengdu, Sichuan 610065, People's Republic of China.
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18
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Patel JD, Ebert M, Ward R, Anderson JM. S. epidermidis biofilm formation: effects of biomaterial surface chemistry and serum proteins. J Biomed Mater Res A 2007; 80:742-51. [PMID: 17177270 DOI: 10.1002/jbm.a.31103] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Most infections due to implanted cardiovascular biomaterials are initiated by bacterial adhesion of Staphylococcus epidermidis, followed by colonization and biofilm formation on the surface of the implant. This study examined the role of serum proteins and material surface chemistry in the formation of S. epidermidis biofilm on polyurethanes (Elasthane 80A, hydrophobic) modified with polyethylene oxide (Elasthane 80A-6PEO, hydrophilic) and fluorocarbon (Elasthane 80A-6F, hydrophobic). Initial adhesion, aggregation, biofilm thickness, viability, and slime formation of S. epidermidis strain, RP62A in phosphate buffered saline (PBS), tryptic soy broth (TBS), and 20% pooled human serum was quantified. In the presence of adsorbed serum proteins, initial bacterial adhesion was suppressed significantly to <2% relative to adhesion in TSB or PBS. However, adhesion, aggregation, and proliferation increased dramatically in the 12-24 h period on Elasthane 80A and Elasthane 80A-6F, which resulted in an extensive network of biofilm. A contrasting trend was observed on the hydrophilic Elasthane 80A-6PEO surface, with minimal bacterial adhesion, which decreased steadily over 24 h. In the presence of serum proteins, an increasingly thick ( approximately 20 mum) biofilm formed on the hydrophobic surfaces over 48 h whereas the formation of a mature biofilm on the hydrophilic surface was impeded with few viable bacteria present over 48 h. Furthermore, slime was detected during the initial phase of bacterial adhesion at 2 h and increased over time with the formation of biofilm. These results have shown that while initial S. epidermidis adhesion is suppressed in the presence of adsorbed proteins, inter-bacterial adhesion possibly aided by slime production leads to the formation of a robust mature biofilm. Also, biomaterial surface chemistry affected biofilm formation and, most notably, polyethylene oxide significantly inhibited S. epidermidis biofilm formation over 48 h in vitro.
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Affiliation(s)
- Jasmine D Patel
- Department of Biomedical Engineering, Case Western Reserve University, 309 Wickenden Bldg, Cleveland, Ohio 44106, USA
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19
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Patel JD, Krupka T, Anderson JM. iNOS-mediated generation of reactive oxygen and nitrogen species by biomaterial-adherent neutrophils. J Biomed Mater Res A 2007; 80:381-90. [PMID: 17001645 DOI: 10.1002/jbm.a.30907] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Infection due to implanted cardiovascular biomaterials is a serious complication initiated by bacterial adhesion to the surface of the implant. The release of reactive oxygen species by neutrophils, particularly superoxide anion, is a well-known bactericidal mechanism. Additionally, nitric oxide (NO) has also been identified as an important cytotoxic mediator in acute and chronic inflammatory responses with enhanced NO production by upregulation of inducible nitric oxide synthase (iNOS). The interaction of NO and superoxide anion will result in the formation of peroxynitrite (OONO-), a potent cytotoxic oxidant. In this study, we have shown that biomaterial-induced neutrophil activation does not cause upregulation of iNOS and activation of iNOS-mediated pathways. However, NO and O2- production does occur over time upon adhesion to a biomaterial and is modulated by biomaterial surface chemistry. With no stimulus, the polyethylene oxide-modified polyurethane induced greater neutrophil activation than did the control as indicated by the increased production of NO and O2- over time. Adherent-stimulated neutrophils generally produced lower amounts of NO over time in comparison with unstimulated cells. Furthermore, there is no evidence of peroxynitrite activity in unstimulated neutrophils adherent to the Elasthane 80A. However, upon stimulation with adherent Staphylococcus epidermidis, peroxynitrite formation did occur. Our results suggest that bactericidal mechanisms in neutrophils involving NO generation (NOS pathway) are further compromised than O2- producing pathways (NADPH oxidase) upon exposure to biomaterials, resulting in a diminished microbial killing capacity, which can increase the probability of device-centered infections.
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Affiliation(s)
- Jasmine D Patel
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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20
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Ward R, Anderson J, McVenes R, Stokes K. In vivo biostability of polyether polyurethanes with fluoropolymer and polyethylene oxide surface modifying endgroups; resistance to metal ion oxidation. J Biomed Mater Res A 2007; 80:34-44. [PMID: 16958046 DOI: 10.1002/jbm.a.30860] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Polyether polyurethanes are subject to oxidation catalyzed by, and through direct (redox) reaction with transition metal ions (metal ion oxidation, MIO). The source of the ions is corrosion of metallic parts within an implanted device. A Shore 80A polyether polyurethane was modified with fluoropolymer (E80AF) or polyethylene oxide (E80AP) surface modifying end groups (SME). The SME migrates to the surface to form a covalently bonded monolayer, while maintaining the bulk properties of the polyurethane. In vitro tests in H(2)O(2) solution indicated that both SME's accelerated MIO. Tubing samples containing cobalt mandrels were implanted in the subcutis of rabbits for up to 2 years. In vivo, E80AF significantly slowed the rate of visible degradation, but did not prevent MIO. E80AP had virtually identical visual performance to the unmodified control in vivo. Infrared spectroscopy and molecular weight correlated well with visual appearance. When cracks were seen, polyether soft segment oxidation was occurring. Both E80AP and the control developed severe loss of molecular weight in vivo. The changes were much less severe for E80AF. Thus, contrary to in vitro test results, the PEO SME had no effect at all on MIO resistance, while the fluoropolymer SME produced a significant improvement in biostability.
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Affiliation(s)
- Robert Ward
- The Polymer Technology Group, 2810 7th Street, Berkeley, California 94710, USA
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21
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MacKintosh EE, Patel JD, Marchant RE, Anderson JM. Effects of biomaterial surface chemistry on the adhesion and biofilm formation of Staphylococcus epidermidis in vitro. J Biomed Mater Res A 2006; 78:836-42. [PMID: 16817192 DOI: 10.1002/jbm.a.30905] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The formation of biofilm, a structured community of bacteria enclosed in slime, is a significant virulence factor in medical-device-centered infection. The development of cardiovascular device infection can be separated into two phases: initial bacterial adhesion and aggregation, followed by proliferation and production of slime. It is possible to modulate the adhesion and biofilm formation of Staphylococcus epidermidis, a commensal skin bacterium commonly found on infected medical devices, through biomaterial surface chemistry. This study examines bacterial adhesion and biofilm formation on surface-modified polyethylene terephthalate (PET), including surfaces with varying hydrophilic, hydrophobic, and ionic character. Bacterial adhesion and biofilm formation were observed over 48 hours in phosphate-buffered saline (PBS) and 20% pooled human serum. The hydrophilic surface (PAAm) had significantly less nonspecific adhesion of bacteria than that in the control (PET) and other surfaces, when cultured in PBS (P < 0.0001). Charged surfaces, both anionic and cationic, had increased adhesion and aggregation of bacteria in comparison with the control (PET) in the presence of serum proteins over 24 hours (P < 0.0001). Bacteria cultured in serum on the charged surfaces did not have significantly different amounts of biofilm formation compared with that of the control (PET) surface after 48 hours. This study showed that biomaterial surface chemistry characteristics impact initial adhesion and aggregation of S. epidermidis on biomaterials.
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Affiliation(s)
- Erin E MacKintosh
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 43703, USA
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22
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DeLegge RL, DeLegge MH. Percutaneous endoscopic gastrostomy evaluation of device materials: are we "failsafe"? Nutr Clin Pract 2006; 20:613-7. [PMID: 16306298 DOI: 10.1177/0115426505020006613] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The development of the percutaneous endoscopic gastrostomy (PEG) tube for enteral access was a revolutionary technological advance. This device has undergone some minor modification over the past 30 years but remains very similar to the original PEG tube design. Use of the PEG tube for gastric enteral feeding access continues to increase yearly both in pediatric and adult populations. One of the difficulties noted with PEG tube use in daily clinical practice is the ultimate degradation of the PEG tube wall material, leading to tube cracking, tearing, and leaking, requiring replacement of the gastrostomy tube. Historically, the predominant polymer material used for PEG tube composition was silicone. More recently, polyurethane has been examined as a potential, more durable material for PEG tube composition. Copolymers, or combinations of silicone and polyurethane and other polymer materials, are currently under investigation as the answer for the development of a bioinert, tissue-friendly, durable, PEG tube composition material.
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23
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Chandra J, Patel JD, Li J, Zhou G, Mukherjee PK, McCormick TS, Anderson JM, Ghannoum MA. Modification of surface properties of biomaterials influences the ability of Candida albicans to form biofilms. Appl Environ Microbiol 2006; 71:8795-801. [PMID: 16332875 PMCID: PMC1317330 DOI: 10.1128/aem.71.12.8795-8801.2005] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida albicans biofilms form on indwelling medical devices (e.g., denture acrylic or intravenous catheters) and are associated with both oral and invasive candidiasis. Here, we determined whether surface modifications of polyetherurethane (Elasthane 80A [E80A]), polycarbonateurethane, and poly(ethyleneterephthalate) (PET) can influence fungal biofilm formation. Polyurethanes were modified by adding 6% polyethylene oxide (6PEO), 6% fluorocarbon, or silicone, while the PET surface was modified to generate hydrophilic, hydrophobic, cationic, or anionic surfaces. Formation of biofilm was quantified by determining metabolic activity and total biomass (dry weight), while its architecture was analyzed by confocal scanning laser microscopy (CSLM). The metabolic activity of biofilm formed by C. albicans on 6PEO-E80A was significantly reduced (by 78%) compared to that of biofilm formed on the nonmodified E80A (optical densities of 0.054 +/- 0.020 and 0.24 +/- 0.10, respectively; P = 0.037). The total biomass of Candida biofilm formed on 6PEO-E80A was 74% lower than that on the nonmodified E80A surface (0.46 +/- 0.15 versus 1.76 +/- 0.32 mg, respectively; P = 0.003). Fungal cells were easily detached from the 6PEO-E80A surface, and we were unable to detect C. albicans biofilm on this surface by CSLM. All other surface modifications allowed formation of C. albicans biofilm, with some differences in thearchitecture. Correlation between contact angle and biofilm formation was observed for polyetherurethane substrates (r = 0.88) but not for PET biomaterials (r = -0.40). This study illustrates that surface modification is a viable approach for identifying surfaces that have antibiofilm characteristics. Investigations into the clinical utility of the identified surfaces are warranted.
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Affiliation(s)
- Jyotsna Chandra
- Center for Medical Mycology, Department of Dermatology, University Hospitals of Cleveland and Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106-5028, USA
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Dadsetan M, Jones JA, Hiltner A, Anderson JM. Surface chemistry mediates adhesive structure, cytoskeletal organization, and fusion of macrophages. J Biomed Mater Res A 2005; 71:439-48. [PMID: 15476262 DOI: 10.1002/jbm.a.30165] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Surface chemistry modulates many critical functions of monocyte/macrophages such as adhesion, fusion, spreading, phagocytosis, and secretion. In this study, we investigated the effect of silicone modification on adhesive structure development and cytoskeletal reorganization of adherent macrophages on polyurethanes. Confocal scanning laser microscopy (CSLM) was used for qualitative and quantitative evaluation of cytoskeletal reorganization of adherent macrophages. Data presented here showed less spreading for adherent cells on silicone-modified materials due to the higher hydrophobicity and protein adsorption profile. This decrease in spreading was accompanied by less F-actin content in adherent cells on silicone-modified polyurethanes and PDMS control, indicating that silicone modification reduces the strength of adhesion. With the addition of interleukin-4 (IL-4) at days 3 and 7 to our culture, adherent cell morphology dramatically changed. The change in morphology led to higher macrophage fusion and foreign body giant cell (FBGC) formation on silicone modified materials after 10 days. In addition, mannose receptor (MR) expression was up-regulated on the silicone-modified polyurethanes and PDMS control in the presence of IL-4. Up-regulation of MR expression suggests an alternatively activated phenotype for adherent macrophages, which is accompanied with an attenuated proinflammatory cytokine production and reactive oxygen secretion. It appears that silicone modification accelerates acquisition of an alternative macrophage and FBGC phenotype, which may then result in increased polyurethane biostability.
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Affiliation(s)
- Mahrokh Dadsetan
- Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106-7202, USA
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