Jan Busk Madsen
Technical University of Denmark
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Jan Busk Madsen.
Colloids and Surfaces B: Biointerfaces | 2014
Nikolaos Nikogeorgos; Jan Busk Madsen; Seunghwan Lee
Lubricating properties of bovine submaxillary mucin (BSM) on a compliant, hydrophobic surface were studied as influenced by impurities, in particular bovine serum albumin (BSA), at macro and nanoscale contacts by means of pin-on-disk tribometry and friction force microscopy (FFM), respectively. At both contact scales, the purity of BSM and the presence of BSA were quantitatively discriminated. The presence of BSA was responsible for higher frictional forces observed from BSM samples containing relatively larger amount of BSA. But, the mechanisms contributing to higher friction forces by BSA were different at different contact scales. At the macroscale contact, higher friction forces were caused by faster and dominant adsorption of BSA into the contacting area under a continuous cycle of desorption and re-adsorption of the macromolecules from tribostress. Nevertheless, all BSMs lowered the interfacial friction forces due to large contact area and a large number of BSM molecules in the contact area. At the nanoscale contact, however, no significant desorption of the macromolecules is expected in tribological contacts because of too small contact area and extremely small number of BSM molecules involved in the contact area. Instead, increasingly higher friction forces with increasing amount of BSA in BSM layer are attributed to higher viscosity caused by BSA in the layer. Comparable size of AFM probes with BSM molecules allowed them to penetrate through the BSM layers and to scratch on the underlying substrates, and thus induced higher friction forces compared to the sliding contact on bare substrates.
Journal of Colloid and Interface Science | 2014
Jan Busk Madsen; Kirsi I. Pakkanen; Seunghwan Lee
Thermostability of bovine submaxillary mucin (BSM) was studied in terms of its structure, hydrodynamic size, surface adsorption, and lubricating properties in the temperature range of 5-85°C. The overall random coil structure of BSM showed a gradual loosening with increasing temperature as characterized by circular dichroism (CD) spectroscopy, but this change was fully reversible upon lowering temperature. Extended heating up to 120 min at 80°C did not make any appreciable changes in the structure of BSM when it was cooled to room temperature. The hydrodynamic size of BSM, as studied by dynamic light scattering (DLS), showed a slight increase after heating at high temperature (80°C). Optical waveguide lightmode spectroscopy (OWLS) studies showed facile adsorption of BSM onto poly(dimethylsiloxane) (PDMS) surface (>180 ng/cm(2)) at room temperature due to its amphiphilic characteristics. Adsorbed mass of BSM was noticeably reduced after heating at 80°C, possibly resulting from its aggregation. BSM showed excellent lubricity at self-mated sliding contacts between PDMS at room temperature or lower (friction coefficient≈0.02), even when BSM solution was pre-heated up to 120 min at 80°C. Gradual degradation of lubricity of BSM was observed with increasing temperature, but it was also reversibly recovered with decreasing temperature. Structural and functional stability of BSM against heating is proposed to originate from heavy glycosylation and lack of higher degree of protein structure in BSM.
Preparative Biochemistry & Biotechnology | 2015
Jan Busk Madsen; Kirsi I. Pakkanen; Lars Duelund; Birte Svensson; Maher Abou Hachem; Seunghwan Lee
In this study, a simple purification protocol is developed to reduce the bovine serum albumin (BSA) content in commercially available bovine submaxillary mucin (BSM). This involved purification of the BSM by one-column anion-exchange chromatography protocol resulting in BSM with greatly reduced BSA content and homogeneously distributed size, and in a high yield of ∼43% from BSM as received from the manufacturer. The purity and composition of commercially acquired BSM were assessed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry, which verified that BSA is the most abundant nonmucinous protein component. The purification effect was evident from a significantly altered circular dichroism (CD) spectrum of BSM after anion-exchange chromatography.
Langmuir | 2015
Bruno Zappone; Navinkumar J. Patil; Jan Busk Madsen; Kirsi I. Pakkanen; Seunghwan Lee
By combining dynamic light scattering, circular dichroism spectroscopy, atomic force microscopy, and surface force apparatus, the conformation of bovine submaxillary mucin in dilute solution and nanomechanical properties of mucin layers adsorbed on mica have been investigated. The samples were prepared by additional chromatographic purification of commercially available products. The mucin molecule was found to have a z-average hydrodynamic diameter of ca. 35 nm in phosphate buffered solution, without any particular secondary or tertiary structure. The contour length of the mucin is larger than, yet of the same order of magnitude as the diameter, indicating that the molecule can be modeled as a relatively rigid polymeric chain due to the large persistence length of the central glycosylated domain. Mucin molecules adsorbed abundantly onto mica from saline buffer, generating polymer-like, long-ranged, repulsive, and nonhysteretic forces upon compression of the adsorbed layers. Detailed analysis of such forces suggests that adsorbed mucins had an elongated conformation favored by the stiffness of the central domain. Acidification of aqueous media was chosen as means to reduce mucin-mucin and mucin-substrate electrostatic interactions. The hydrodynamic diameter in solution did not significantly change when the pH was lowered, showing that the large persistence length of the mucin molecule is due to steric hindrance between sugar chains, rather than electrostatic interactions. Remarkably, the force generated by an adsorbed layer with a fixed surface coverage also remained unaltered upon acidification. This observation can be linked to the surface-protective, pH-resistant role of bovine submaxillary mucin in the variable environmental conditions of the oral cavity.
Langmuir | 2015
Jan Busk Madsen; Birte Svensson; Maher Abou Hachem; Seunghwan Lee
The effects of proteolytic digestion on bovine submaxillary mucin (BSM) were investigated in terms of changes in size, secondary structure, surface adsorption, and lubricating properties. Two proteases with distinctly different cleavage specificities, namely trypsin and pepsin, were employed. SDS-PAGE analysis with staining for proteins and carbohydrate moieties showed that only the unglycosylated terminal regions of BSM were degraded by the proteases. Size exclusion chromatography (SEC) and dynamic light scattering (DLS) analyses indicated that tryptic digestion mainly led to the reduction in size, whereas pepsin digestion rather caused an increase in the size of BSM. Less complete cleavage in terminal peptide regions by pepsin and subsequent aggregation were possibly responsible for the increased size. Far-UV circular dichroism (CD) spectra of the protease-treated BSM showed a slight change in the secondary structure owing to the removal of terminal domains, but the overall random coil conformation adopted by the central glycosylated domain remained dominant and essentially unchanged. Surface adsorption properties as characterized by optical waveguide lightmode spectroscopy (OWLS) showed that tryptic digestion of BSM resulted in a decrease in the adsorbed mass, but pepsin digestion led to a slight increase in the adsorbed mass onto a hydrophobic surface compared to intact BSM. This is in agreement with the partial preservation of peptide segments in the terminal regions after pepsin digestion as confirmed by SEC and DLS studies. Despite a contrast in the adsorbed amount of the protease-treated BSMs onto the surface, both proteases substantially deteriorated the lubricating capabilities of BSM at a hydrophobic interface. The present study supports the notion that the terminal domains of BSM are critical to the adsorption and lubricating properties of BSM at hydrophobic interfaces.
Langmuir | 2016
Jan Busk Madsen; Javier Sotres; Kirsi I. Pakkanen; Petr Efler; Birte Svensson; Maher Abou Hachem; Thomas Arnebrant; Seunghwan Lee
The structural and mechanical properties of thin films generated from two types of mucins, namely, bovine submaxillary mucin (BSM) and porcine gastric mucin (PGM) in aqueous environment were investigated with several bulk and surface analytical techniques. Both mucins generated hydrated films on hydrophobic polydimethylsiloxane (PDMS) surfaces from spontaneous adsorption arising from their amphiphilic characteristic. However, BSM formed more elastic films than PGM at neutral pH condition. This structural difference was manifested from the initial film formation processes to the responses to shear stresses applied to the films. Acidification of environmental pH led to strengthening the elastic character of BSM films with increased adsorbed mass, whereas an opposite trend was observed for PGM films. We propose that this contrast originates from that negatively charged motifs are present for both the central and terminal regions of BSM molecule, whereas a similar magnitude of negative charges is localized at the termini of PGM molecule. Given that hydrophobic motifs acting as an anchor are also localized in the terminal region, electrostatic repulsion between anchoring units of PGM molecules on a nonpolar PDMS surface leads to weakening of the mechanical integrity of the films.
International Journal of Biological Macromolecules | 2015
Kirsi I. Pakkanen; Jan Busk Madsen; Seunghwan Lee
In the present study, the conformational changes of bovine submaxillary mucin (BSM) adsorbed on a hydrophobic surface (polystyrene (PS)) as a function of concentration in bulk solution (up to 2mg/mL) have been investigated with biomolecular probe-based approaches, including bicinchoninic acid (BCA), enzyme-linked immunosorbent assay (EIA), and enzyme-linked lectin assay (ELLA). The conformation and hydrodynamic diameter of highly purified BSM molecules, as characterized by circular dichroism (CD) spectroscopy and dynamic light scattering (DLS), respectively, showed a slight, yet gradual coiling and compaction in response to the increase in BSM concentration in bulk solution. Adsorbed masses of BSM onto hydrophobic surface, as probe by BCA, showed a continuously increasing trend up to 2mg/mL. But, the signals from EIA and ELLA, which probe the concentration of available unglycosylated C-terminals and the central glycosylated regions, respectively, showed complicated non-linear responses with increasing surface concentration. The results from this study support the conventional amphiphilic, triblock model of BSM in the adsorption onto hydrophobic surface from aqueous solution. The biomolecular probe-based approaches employed in this study, however, provided further details on the conformational changes of BSM on surface, in particular the accessibility of glycosylated and unglycosylated domains with increasing surface concentration.
international conference on biomedical engineering | 2013
Seunghwan Lee; Jan Busk Madsen; Kirsi I. Pakkanen
Feasibility of bovine submaxillary mucin (BSM) films generated via spontaneous adsorption from aqueous solutions onto polydimethylsiloxane (PDMS) and polystyrene (PS) surfaces have been investigated as biomimetic coatings for polymeric biomaterials. Two attributes as biomedical coatings, namely anti-fouling properties and lubricity, have been focused on in this study. Optical waveguide light-mode spectroscopy (OWLS) and fluorescence microscopy studies have shown that albumin, fibrinogen, immunoglobulin G, and serum rapidly adsorb onto BSM layers formed on PDMS and PS surfaces. Pin-on-disk tribometry, employing compliant PDMS as tribopairs, has shown that BSM coatings generated on PDMS surface via spontaneous adsorption from aqueous solution has effective lubricating properties, but for very limited duration only.
Journal of Colloid and Interface Science | 2014
Javier Sotres; Jan Busk Madsen; Thomas Arnebrant; Seunghwan Lee
international conference on biomedical engineering | 2013
Jan Busk Madsen; Kirsi I. Pakkanen; Seunghwan Lee