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Self-assembly and modular functionalization of three-dimensional crystals from oppositely charged proteins.

Liljeström V, Mikkilä J, Kostiainen MA - Nat Commun (2014)

Bottom Line: Well-developed, especially DNA-based, methods for their preparation exist, yet most techniques concentrate on molecular and synthetic nanoparticle systems in non-biocompatible environment.Here we describe the self-assembly and characterization of binary solids that consist of crystalline arrays of native biomacromolecules.Importantly, the whole preparation process takes place at room temperature in a mild aqueous medium allowing the processing of delicate biological building blocks into ordered structures with lattice constants in the nanometre range.

View Article: PubMed Central - PubMed

Affiliation: 1] Biohybrid Materials Group, Department of Biotechnology and Chemical Technology, Aalto University, 00076 Aalto, Finland [2] Molecular Materials Group, Department of Applied Physics, Aalto University, 00076 Aalto, Finland.

ABSTRACT
Multicomponent crystals and nanoparticle superlattices are a powerful approach to integrate different materials into ordered nanostructures. Well-developed, especially DNA-based, methods for their preparation exist, yet most techniques concentrate on molecular and synthetic nanoparticle systems in non-biocompatible environment. Here we describe the self-assembly and characterization of binary solids that consist of crystalline arrays of native biomacromolecules. We electrostatically assembled cowpea chlorotic mottle virus particles and avidin proteins into heterogeneous crystals, where the virus particles adopt a non-close-packed body-centred cubic arrangement held together by avidin. Importantly, the whole preparation process takes place at room temperature in a mild aqueous medium allowing the processing of delicate biological building blocks into ordered structures with lattice constants in the nanometre range. Furthermore, the use of avidin-biotin interaction allows highly selective pre- or post-functionalization of the protein crystals in a modular way with different types of functional units, such as fluorescent dyes, enzymes and plasmonic nanoparticles.

No MeSH data available.


Related in: MedlinePlus

Comparison of CCMV crystals formed with avidin and PAMAM-G6.(a) 2D scattering patterns and azimuthally integrated curves show that patchy avidin particles direct the formation of an open bcc CCMV-lattice, whereas isotropically charged PAMAM-G6 forms fcc crystal lattices with CCMV. Top two curves are vertically offset for clarity. (b) Integrated and indexed SAXS curve measured from self-assembled CCMV–PAMAM-G6 crystal and comparison with a calculated finite fcc structure using a core-shell model. (c) Quadratic Miller indices of assigned reflections for  structure versus measured q-vector positions. Nine peaks can be indexed to the given structure. Solid line presents a linear fit, which yields a lattice parameter aSAXS=40.5 nm. (d) Crystallographic arrangement and lattice parameter details of suggested binary structures of CCMV–avidin, CCMV–PAMAM-G6 and comparison with our previously reported CCMV–AuNP AB8fcc-type lattice20.
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f4: Comparison of CCMV crystals formed with avidin and PAMAM-G6.(a) 2D scattering patterns and azimuthally integrated curves show that patchy avidin particles direct the formation of an open bcc CCMV-lattice, whereas isotropically charged PAMAM-G6 forms fcc crystal lattices with CCMV. Top two curves are vertically offset for clarity. (b) Integrated and indexed SAXS curve measured from self-assembled CCMV–PAMAM-G6 crystal and comparison with a calculated finite fcc structure using a core-shell model. (c) Quadratic Miller indices of assigned reflections for structure versus measured q-vector positions. Nine peaks can be indexed to the given structure. Solid line presents a linear fit, which yields a lattice parameter aSAXS=40.5 nm. (d) Crystallographic arrangement and lattice parameter details of suggested binary structures of CCMV–avidin, CCMV–PAMAM-G6 and comparison with our previously reported CCMV–AuNP AB8fcc-type lattice20.

Mentions: Assuming a spherical 28 nm diameter CCMV particle, a close-packed bcc structure would have a unit cell size of 32.3 nm. According to SAXS, the unit cell size of the final bcc structure of CCMV–avidin complex is 35.0 nm. In this unit cell, the smallest centre-to-centre distance between CCMV particles is dCCMV–CCMV=a✓3/2=30.3 nm leaving an ~2.3 nm spacing between adjacent CCMV particles (for example, between CCMV particles in positions (0,0,0) and (0.5,0.5,0.5) in the unit cell). The bcc structure includes both tetrahedral and octahedral voids when CCMV is located in the lattice points of the unit cell. The tetrahedral voids in this unit cell have a diameter of 11.1 nm and the octahedral voids have a diameter of 7.0 nm. Values indicate that avidin can occupy both the tetrahedral and the octahedral voids. Avidin has to be located mainly in the edge of the voids to allow electrostatic bridging between the CCMV particles since the voids are too large for one avidin alone to fill and the space between two adjacent CCMV particles is too narrow to host even one avidin. Furthermore, the tetrahedral orientation of the positive patches of avidin can optimize their interaction with CCMV when located in the tetrahedral void. The CCMV particles do not form a close-packed structure and the voids are overlapping, which indicates that avidin can still form a continuous matrix around the CCMV particles. Based on the SAXS data and cryo-TEM images (Fig. 3), we argue that CCMV occupies the lattice points of the bcc structure, and the avidin proteins are distributed within the corners of tetrahedral and octahedral inter-particle voids in the lattice to yield a AB12bcc structure (Fig. 4, and the Supplementary Discussion). Such a crystallographic arrangement has previously been observed for instance with bcc-packed γ-cyclodextrin6 cubes held together by potassium ions50.


Self-assembly and modular functionalization of three-dimensional crystals from oppositely charged proteins.

Liljeström V, Mikkilä J, Kostiainen MA - Nat Commun (2014)

Comparison of CCMV crystals formed with avidin and PAMAM-G6.(a) 2D scattering patterns and azimuthally integrated curves show that patchy avidin particles direct the formation of an open bcc CCMV-lattice, whereas isotropically charged PAMAM-G6 forms fcc crystal lattices with CCMV. Top two curves are vertically offset for clarity. (b) Integrated and indexed SAXS curve measured from self-assembled CCMV–PAMAM-G6 crystal and comparison with a calculated finite fcc structure using a core-shell model. (c) Quadratic Miller indices of assigned reflections for  structure versus measured q-vector positions. Nine peaks can be indexed to the given structure. Solid line presents a linear fit, which yields a lattice parameter aSAXS=40.5 nm. (d) Crystallographic arrangement and lattice parameter details of suggested binary structures of CCMV–avidin, CCMV–PAMAM-G6 and comparison with our previously reported CCMV–AuNP AB8fcc-type lattice20.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4109007&req=5

f4: Comparison of CCMV crystals formed with avidin and PAMAM-G6.(a) 2D scattering patterns and azimuthally integrated curves show that patchy avidin particles direct the formation of an open bcc CCMV-lattice, whereas isotropically charged PAMAM-G6 forms fcc crystal lattices with CCMV. Top two curves are vertically offset for clarity. (b) Integrated and indexed SAXS curve measured from self-assembled CCMV–PAMAM-G6 crystal and comparison with a calculated finite fcc structure using a core-shell model. (c) Quadratic Miller indices of assigned reflections for structure versus measured q-vector positions. Nine peaks can be indexed to the given structure. Solid line presents a linear fit, which yields a lattice parameter aSAXS=40.5 nm. (d) Crystallographic arrangement and lattice parameter details of suggested binary structures of CCMV–avidin, CCMV–PAMAM-G6 and comparison with our previously reported CCMV–AuNP AB8fcc-type lattice20.
Mentions: Assuming a spherical 28 nm diameter CCMV particle, a close-packed bcc structure would have a unit cell size of 32.3 nm. According to SAXS, the unit cell size of the final bcc structure of CCMV–avidin complex is 35.0 nm. In this unit cell, the smallest centre-to-centre distance between CCMV particles is dCCMV–CCMV=a✓3/2=30.3 nm leaving an ~2.3 nm spacing between adjacent CCMV particles (for example, between CCMV particles in positions (0,0,0) and (0.5,0.5,0.5) in the unit cell). The bcc structure includes both tetrahedral and octahedral voids when CCMV is located in the lattice points of the unit cell. The tetrahedral voids in this unit cell have a diameter of 11.1 nm and the octahedral voids have a diameter of 7.0 nm. Values indicate that avidin can occupy both the tetrahedral and the octahedral voids. Avidin has to be located mainly in the edge of the voids to allow electrostatic bridging between the CCMV particles since the voids are too large for one avidin alone to fill and the space between two adjacent CCMV particles is too narrow to host even one avidin. Furthermore, the tetrahedral orientation of the positive patches of avidin can optimize their interaction with CCMV when located in the tetrahedral void. The CCMV particles do not form a close-packed structure and the voids are overlapping, which indicates that avidin can still form a continuous matrix around the CCMV particles. Based on the SAXS data and cryo-TEM images (Fig. 3), we argue that CCMV occupies the lattice points of the bcc structure, and the avidin proteins are distributed within the corners of tetrahedral and octahedral inter-particle voids in the lattice to yield a AB12bcc structure (Fig. 4, and the Supplementary Discussion). Such a crystallographic arrangement has previously been observed for instance with bcc-packed γ-cyclodextrin6 cubes held together by potassium ions50.

Bottom Line: Well-developed, especially DNA-based, methods for their preparation exist, yet most techniques concentrate on molecular and synthetic nanoparticle systems in non-biocompatible environment.Here we describe the self-assembly and characterization of binary solids that consist of crystalline arrays of native biomacromolecules.Importantly, the whole preparation process takes place at room temperature in a mild aqueous medium allowing the processing of delicate biological building blocks into ordered structures with lattice constants in the nanometre range.

View Article: PubMed Central - PubMed

Affiliation: 1] Biohybrid Materials Group, Department of Biotechnology and Chemical Technology, Aalto University, 00076 Aalto, Finland [2] Molecular Materials Group, Department of Applied Physics, Aalto University, 00076 Aalto, Finland.

ABSTRACT
Multicomponent crystals and nanoparticle superlattices are a powerful approach to integrate different materials into ordered nanostructures. Well-developed, especially DNA-based, methods for their preparation exist, yet most techniques concentrate on molecular and synthetic nanoparticle systems in non-biocompatible environment. Here we describe the self-assembly and characterization of binary solids that consist of crystalline arrays of native biomacromolecules. We electrostatically assembled cowpea chlorotic mottle virus particles and avidin proteins into heterogeneous crystals, where the virus particles adopt a non-close-packed body-centred cubic arrangement held together by avidin. Importantly, the whole preparation process takes place at room temperature in a mild aqueous medium allowing the processing of delicate biological building blocks into ordered structures with lattice constants in the nanometre range. Furthermore, the use of avidin-biotin interaction allows highly selective pre- or post-functionalization of the protein crystals in a modular way with different types of functional units, such as fluorescent dyes, enzymes and plasmonic nanoparticles.

No MeSH data available.


Related in: MedlinePlus