Arja Paananen - Academia.edu (original) (raw)

Papers by Arja Paananen

Cellulose

In this study, tall oil fatty acid ester of softwood kraft lignin (TOFA-L) was used to prepare TO... more In this study, tall oil fatty acid ester of softwood kraft lignin (TOFA-L) was used to prepare TOFA lignin nanoparticles (TLNP) in water. The average diameters for two prepared TLNPs in 0.1 mg/ml concentration were 140 nm and 160 nm. TLNPs were attached covalently onto modified and unmodified cellulose fibres to form an antimicrobial composite material. The modified cellulose fibres contained reactive allylic double bonds with a degree of substitution of 0.05. The antimicrobial properties of both TLNPs and TLNP coated fibres (TLNP-C) were studied against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa using silver nanospheres (average size 10 nm) and Lignoboost lignin particles with 300 and 400 nm sizes as references. Antimicrobial activity of the samples was stronger against Gram-positive S. aureus cells than against Gram-negative target microbes E. coli and P. aeruginosa.

Chemistry (Weinheim an der Bergstrasse, Germany), Jan 24, 2018

Hydrophobins have raised lots of interest as powerful surface adhesives. However, it remains larg... more Hydrophobins have raised lots of interest as powerful surface adhesives. However, it remains largely unexplored how their strong and versatile surface adhesion is linked to their unique amphiphilic structural features. Here, we develop an AFM-based single-molecule force spectroscopy assay to quantitatively measure the binding strength of hydrophobin to various types of surfaces both in isolation and in preformed protein films. We find that individual class II hydrophobins (HFBI) bind strongly to hydrophobic surfaces but weakly to hydrophilic ones. After self-assembly into protein films, they show much stronger binding strength to both surfaces due to the cooperativity of different interactions at nanoscale. Such self-assembly enhanced surface binding may serve as a general design principle for synthetic bioactive adhesives.

The Journal of Physical Chemistry Letters

Biochemistry Usa, Jun 1, 2003

Hydrophobins are highly surface-active proteins that are specific to filamentous fungi. They func... more Hydrophobins are highly surface-active proteins that are specific to filamentous fungi. They function as coatings on various fungal structures, enable aerial growth of hyphae, and facilitate attachment to surfaces. Little is known about their structures and structure-function relationships. In this work we show highly organized surface layers of hydrophobins, representing the most detailed structural study of hydrophobin films so far. Langmuir-Blodgett films of class II hydrophobins HFBI and HFBII from Trichoderma reesei were prepared and analyzed by atomic force microscopy. The films showed highly ordered two-dimensional crystalline structures. By combining our recent results on small-angle X-ray scattering of hydrophobin solutions, we found that the unit cells in the films have dimensions similar to those of tetrameric aggregates found in solutions. Further analysis leads to a model in which the building blocks of the two-dimensional crystals are shape-persistent supramolecules consisting of four hydrophobin molecules. The results also indicate functional and structural differences between HFBI and HFBII that help to explain differences in their properties. The possibility that the highly organized surface assemblies of hydrophobins could allow a route for manufacturing functional surfaces is suggested.

ACS applied materials & interfaces, Jan 10, 2016

We demonstrate a label-free biosensor concept based on specific receptor modules providing immobi... more We demonstrate a label-free biosensor concept based on specific receptor modules providing immobilization and selectivity to the desired analyte molecules, and on charge sensing with a graphene field effect transistor. The receptor modules are fusion proteins in which small hydrophobin proteins act as the anchor to immobilize the receptor moiety. The functionalization of the graphene sensor is a single step process based on directed self-assembly of the receptor modules on a hydrophobic surface. The modules are produced separately in fungi or plants and purified before use. The modules form a dense and well-oriented monolayer on the graphene transistor channel and the receptor module monolayer can be removed and a new module monolayer with a different selectivity can be assembled in situ. The receptor module monolayers survive drying, showing that the functionalized devices can be stored and have a reasonable shelf-life. The sensor is tested with small charged peptides and large imm...

Book of Abstracts (CD) 2009 MRS Spring Meeting (2009MRS). San Francisco, USA, 13 - 17 Apr. 2009

Advanced Materials Interfaces, 2015

Lucia/The Nanoscience and Technology of Renewable Biomaterials, 2009

ACS Symposium Series, 2003

ABSTRACT The atomic force microscope (AFM) colloidal probe technique has been used to investigate... more ABSTRACT The atomic force microscope (AFM) colloidal probe technique has been used to investigate forces between cellulose beads as well as cellulose beads and mica in aqueous solution, and the interaction between cellulose surfaces in xylan solutions. Several observations of the behaviour of the cellulose beads were made. Swelling of the beads in aqueous solutions is rather slow. Thus, it is important to let the beads equilibrate before measurements. The beads are somewhat compressed when forced together to constant compliance, but relax back to their original shape in a few minutes. A long-range electrostatic repulsion between cellulose and mica occurs on approach. The xylan concentration in solution affects the forces between two cellulose surfaces. When the concentration increases from 10-100 mg/l more xylan adsorbs slowly and irreversibly on the cellulose leading to an increasingly long-range and stronger repulsion between the surfaces on approach. Adhesion between the layers is very low and seems to be due to entanglement of polymer chains. Studies of the adsorption of xylan (100 mg/l) on cellulose films with a quartz crystal microbalance with dissipation (QCM-D) verify that a thick, water-swollen layer of xylan is formed by slow adsorption. It has been proposed that adsorbed xylan on fibre surfaces increases paper strength. We conclude that this must be associated with the behaviour of the adsorbed layers of xylan on drying.

ACS Symposium Series, 2003

... Michael Bailey is thanked for production of the enzyme in lab-fermenters, and Tuomas Haltia f... more ... Michael Bailey is thanked for production of the enzyme in lab-fermenters, and Tuomas Haltia for EPR analysis. ... VehmaanperäJ, Elovainio M, Haakana H, Joutsjoki V, Lantto R, Mäntylä A, Paloheimo M, Suominen P, Londesborough J, Miettinen-Oinonen A (April 1997) Cellulases ...

Biomacromolecules, Jan 9, 2015

Hydrophobins are extracellular proteins produced by filamentous fungi. They show a variety of fun... more Hydrophobins are extracellular proteins produced by filamentous fungi. They show a variety of functions at interfaces that help fungi to adapt to their environment by, for example, adhesion, formation of coatings, and lowering the surface tension of water. Hydrophobins fold into a globular structure and have a distinct hydrophobic patch on their surface that makes these proteins amphiphilic. Their amphiphilicity implies interfacial assembly, but observations indicate that intermolecular interactions also contribute to their functional properties. Here, we used the class II hydrophobin HFBI from Trichoderma reesei as a model to understand the structural basis for the function of hydrophobins. Four different variants were made in which charged residues were mutated. The residues were chosen to probe the role of different regions of the hydrophilic part of the proteins. Effects of the mutations were studied by analyzing the formation and structure of self-assembled layers, multimerizat...

Colloids and surfaces. B, Biointerfaces, Jan 4, 2015

Enzymes can be used to enable a specific and controlled approach for structural modifications of ... more Enzymes can be used to enable a specific and controlled approach for structural modifications of protein networks in food technology. Enzymatically induced cross-links between proteins in the continuous phase and/or at interfaces result in better stabilisation and enhanced material properties in foams and emulsions. In this work the interfacial properties of β-casein and к-casein films were investigated with a special focus on the mechanism of transglutaminase (TG) induced cross-linking at the air/water interface. The surface rheology results showed that for the enhanced interfacial strength the order and timing of TG addition matters: TG reaction was most effective when the enzyme was applied during adsorption of proteins to the interface. Differences observed between enzymatic cross-linking of β-casein and к-casein at the air/water interface verified the importance of molecular structure and close packing for formation of an elastic protein network.

The journal of physical chemistry. B, Jan 2, 2014

Micelles can be formed from coenzyme Q10 (CoQ10) and dipotassium glycyrrhizate (GZK2) by using an... more Micelles can be formed from coenzyme Q10 (CoQ10) and dipotassium glycyrrhizate (GZK2) by using an inclusion complex of CoQ10 with γ-cyclodextrin (γ-CD). The mechanism of micelle formation was kinetically investigated. Adding GZK2 to a supersaturated solution of the CoQ10/γ-CD inclusion complex led to a linear increase in the solubility of CoQ10 due to the formation of micelles of CoQ10 when the molar ratio of GZK2/γ-CD increased to ∼1.6, after which the concentration remained constant. The equilibrium constant K for micelle formation was 0.68 (-) and the ratio of GZK2 to CoQ10 was 1. These results suggest that the formation of CoQ10 micelles with GZK2 might proceed via the displacement of CoQ10 by GZK2 in the γ-CD cavity followed by the formation of CoQ10 micelles.

Food Hydrocolloids, 2015

ABSTRACT The colloidal size and charge of oat protein isolate (OPI) at pH 7.2 and 9.0 with/withou... more ABSTRACT The colloidal size and charge of oat protein isolate (OPI) at pH 7.2 and 9.0 with/without transglutaminase (TG) treatment were investigated and related to its surface activity at airewater interface. OPI was prepared from defatted oat flour. It was dispersed in water (pH 7.2), or in buffer (pH 9.0) and the soluble fraction (supernatant after centrifugation at 10 000 x g) was used for particle size, zeta-potential and dynamic surface tension measurements. Dispersions were found to be electrostatically stable (zeta-potential > - 35 mV) with average particle sizes of similar to 70 nm at pH 7.2 and similar to 30 nm at pH 9.0. When diluted at pH 7.2, dissociation and re-association of the particles occurred resulting in increased polydispersity and increased size, while at pH 9.0 particle size and zeta-potential were unchanged after dilution. Dynamic surface tension measurements revealed slower adsorption dynamics and higher final surface tension values at pH 9.0 than at pH 7.2. TG-treatment of OPI dispersion resulted in formation of inter-molecular covalent linkages and led to decreased average particle size and increased stability against dilution in OPI dispersions at neutral pH. TG-treated proteins showed increased negative charge at pH 7.2 and resulted in higher surface tension values compared to the untreated samples. The topography images of adsorbed or spread layers of OPI at a/w interface revealed that oat globulins were effectively adsorbed and existed as monomeric particles or formed aggregates at the interface depending on pH.

Nature Structural Biology, 2002

Cellulose

In this study, tall oil fatty acid ester of softwood kraft lignin (TOFA-L) was used to prepare TO... more In this study, tall oil fatty acid ester of softwood kraft lignin (TOFA-L) was used to prepare TOFA lignin nanoparticles (TLNP) in water. The average diameters for two prepared TLNPs in 0.1 mg/ml concentration were 140 nm and 160 nm. TLNPs were attached covalently onto modified and unmodified cellulose fibres to form an antimicrobial composite material. The modified cellulose fibres contained reactive allylic double bonds with a degree of substitution of 0.05. The antimicrobial properties of both TLNPs and TLNP coated fibres (TLNP-C) were studied against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa using silver nanospheres (average size 10 nm) and Lignoboost lignin particles with 300 and 400 nm sizes as references. Antimicrobial activity of the samples was stronger against Gram-positive S. aureus cells than against Gram-negative target microbes E. coli and P. aeruginosa.

Chemistry (Weinheim an der Bergstrasse, Germany), Jan 24, 2018

Hydrophobins have raised lots of interest as powerful surface adhesives. However, it remains larg... more Hydrophobins have raised lots of interest as powerful surface adhesives. However, it remains largely unexplored how their strong and versatile surface adhesion is linked to their unique amphiphilic structural features. Here, we develop an AFM-based single-molecule force spectroscopy assay to quantitatively measure the binding strength of hydrophobin to various types of surfaces both in isolation and in preformed protein films. We find that individual class II hydrophobins (HFBI) bind strongly to hydrophobic surfaces but weakly to hydrophilic ones. After self-assembly into protein films, they show much stronger binding strength to both surfaces due to the cooperativity of different interactions at nanoscale. Such self-assembly enhanced surface binding may serve as a general design principle for synthetic bioactive adhesives.

The Journal of Physical Chemistry Letters

Biochemistry Usa, Jun 1, 2003

Hydrophobins are highly surface-active proteins that are specific to filamentous fungi. They func... more Hydrophobins are highly surface-active proteins that are specific to filamentous fungi. They function as coatings on various fungal structures, enable aerial growth of hyphae, and facilitate attachment to surfaces. Little is known about their structures and structure-function relationships. In this work we show highly organized surface layers of hydrophobins, representing the most detailed structural study of hydrophobin films so far. Langmuir-Blodgett films of class II hydrophobins HFBI and HFBII from Trichoderma reesei were prepared and analyzed by atomic force microscopy. The films showed highly ordered two-dimensional crystalline structures. By combining our recent results on small-angle X-ray scattering of hydrophobin solutions, we found that the unit cells in the films have dimensions similar to those of tetrameric aggregates found in solutions. Further analysis leads to a model in which the building blocks of the two-dimensional crystals are shape-persistent supramolecules consisting of four hydrophobin molecules. The results also indicate functional and structural differences between HFBI and HFBII that help to explain differences in their properties. The possibility that the highly organized surface assemblies of hydrophobins could allow a route for manufacturing functional surfaces is suggested.

ACS applied materials & interfaces, Jan 10, 2016

We demonstrate a label-free biosensor concept based on specific receptor modules providing immobi... more We demonstrate a label-free biosensor concept based on specific receptor modules providing immobilization and selectivity to the desired analyte molecules, and on charge sensing with a graphene field effect transistor. The receptor modules are fusion proteins in which small hydrophobin proteins act as the anchor to immobilize the receptor moiety. The functionalization of the graphene sensor is a single step process based on directed self-assembly of the receptor modules on a hydrophobic surface. The modules are produced separately in fungi or plants and purified before use. The modules form a dense and well-oriented monolayer on the graphene transistor channel and the receptor module monolayer can be removed and a new module monolayer with a different selectivity can be assembled in situ. The receptor module monolayers survive drying, showing that the functionalized devices can be stored and have a reasonable shelf-life. The sensor is tested with small charged peptides and large imm...

Book of Abstracts (CD) 2009 MRS Spring Meeting (2009MRS). San Francisco, USA, 13 - 17 Apr. 2009

Advanced Materials Interfaces, 2015

Lucia/The Nanoscience and Technology of Renewable Biomaterials, 2009

ACS Symposium Series, 2003

ABSTRACT The atomic force microscope (AFM) colloidal probe technique has been used to investigate... more ABSTRACT The atomic force microscope (AFM) colloidal probe technique has been used to investigate forces between cellulose beads as well as cellulose beads and mica in aqueous solution, and the interaction between cellulose surfaces in xylan solutions. Several observations of the behaviour of the cellulose beads were made. Swelling of the beads in aqueous solutions is rather slow. Thus, it is important to let the beads equilibrate before measurements. The beads are somewhat compressed when forced together to constant compliance, but relax back to their original shape in a few minutes. A long-range electrostatic repulsion between cellulose and mica occurs on approach. The xylan concentration in solution affects the forces between two cellulose surfaces. When the concentration increases from 10-100 mg/l more xylan adsorbs slowly and irreversibly on the cellulose leading to an increasingly long-range and stronger repulsion between the surfaces on approach. Adhesion between the layers is very low and seems to be due to entanglement of polymer chains. Studies of the adsorption of xylan (100 mg/l) on cellulose films with a quartz crystal microbalance with dissipation (QCM-D) verify that a thick, water-swollen layer of xylan is formed by slow adsorption. It has been proposed that adsorbed xylan on fibre surfaces increases paper strength. We conclude that this must be associated with the behaviour of the adsorbed layers of xylan on drying.

ACS Symposium Series, 2003

... Michael Bailey is thanked for production of the enzyme in lab-fermenters, and Tuomas Haltia f... more ... Michael Bailey is thanked for production of the enzyme in lab-fermenters, and Tuomas Haltia for EPR analysis. ... VehmaanperäJ, Elovainio M, Haakana H, Joutsjoki V, Lantto R, Mäntylä A, Paloheimo M, Suominen P, Londesborough J, Miettinen-Oinonen A (April 1997) Cellulases ...

Biomacromolecules, Jan 9, 2015

Hydrophobins are extracellular proteins produced by filamentous fungi. They show a variety of fun... more Hydrophobins are extracellular proteins produced by filamentous fungi. They show a variety of functions at interfaces that help fungi to adapt to their environment by, for example, adhesion, formation of coatings, and lowering the surface tension of water. Hydrophobins fold into a globular structure and have a distinct hydrophobic patch on their surface that makes these proteins amphiphilic. Their amphiphilicity implies interfacial assembly, but observations indicate that intermolecular interactions also contribute to their functional properties. Here, we used the class II hydrophobin HFBI from Trichoderma reesei as a model to understand the structural basis for the function of hydrophobins. Four different variants were made in which charged residues were mutated. The residues were chosen to probe the role of different regions of the hydrophilic part of the proteins. Effects of the mutations were studied by analyzing the formation and structure of self-assembled layers, multimerizat...

Colloids and surfaces. B, Biointerfaces, Jan 4, 2015

Enzymes can be used to enable a specific and controlled approach for structural modifications of ... more Enzymes can be used to enable a specific and controlled approach for structural modifications of protein networks in food technology. Enzymatically induced cross-links between proteins in the continuous phase and/or at interfaces result in better stabilisation and enhanced material properties in foams and emulsions. In this work the interfacial properties of β-casein and к-casein films were investigated with a special focus on the mechanism of transglutaminase (TG) induced cross-linking at the air/water interface. The surface rheology results showed that for the enhanced interfacial strength the order and timing of TG addition matters: TG reaction was most effective when the enzyme was applied during adsorption of proteins to the interface. Differences observed between enzymatic cross-linking of β-casein and к-casein at the air/water interface verified the importance of molecular structure and close packing for formation of an elastic protein network.

The journal of physical chemistry. B, Jan 2, 2014

Micelles can be formed from coenzyme Q10 (CoQ10) and dipotassium glycyrrhizate (GZK2) by using an... more Micelles can be formed from coenzyme Q10 (CoQ10) and dipotassium glycyrrhizate (GZK2) by using an inclusion complex of CoQ10 with γ-cyclodextrin (γ-CD). The mechanism of micelle formation was kinetically investigated. Adding GZK2 to a supersaturated solution of the CoQ10/γ-CD inclusion complex led to a linear increase in the solubility of CoQ10 due to the formation of micelles of CoQ10 when the molar ratio of GZK2/γ-CD increased to ∼1.6, after which the concentration remained constant. The equilibrium constant K for micelle formation was 0.68 (-) and the ratio of GZK2 to CoQ10 was 1. These results suggest that the formation of CoQ10 micelles with GZK2 might proceed via the displacement of CoQ10 by GZK2 in the γ-CD cavity followed by the formation of CoQ10 micelles.

Food Hydrocolloids, 2015

ABSTRACT The colloidal size and charge of oat protein isolate (OPI) at pH 7.2 and 9.0 with/withou... more ABSTRACT The colloidal size and charge of oat protein isolate (OPI) at pH 7.2 and 9.0 with/without transglutaminase (TG) treatment were investigated and related to its surface activity at airewater interface. OPI was prepared from defatted oat flour. It was dispersed in water (pH 7.2), or in buffer (pH 9.0) and the soluble fraction (supernatant after centrifugation at 10 000 x g) was used for particle size, zeta-potential and dynamic surface tension measurements. Dispersions were found to be electrostatically stable (zeta-potential > - 35 mV) with average particle sizes of similar to 70 nm at pH 7.2 and similar to 30 nm at pH 9.0. When diluted at pH 7.2, dissociation and re-association of the particles occurred resulting in increased polydispersity and increased size, while at pH 9.0 particle size and zeta-potential were unchanged after dilution. Dynamic surface tension measurements revealed slower adsorption dynamics and higher final surface tension values at pH 9.0 than at pH 7.2. TG-treatment of OPI dispersion resulted in formation of inter-molecular covalent linkages and led to decreased average particle size and increased stability against dilution in OPI dispersions at neutral pH. TG-treated proteins showed increased negative charge at pH 7.2 and resulted in higher surface tension values compared to the untreated samples. The topography images of adsorbed or spread layers of OPI at a/w interface revealed that oat globulins were effectively adsorbed and existed as monomeric particles or formed aggregates at the interface depending on pH.

Nature Structural Biology, 2002