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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

Functionalization with fluorescent dyes.Crystals (cryst.) functionalized with (a) biotin (5-fluorescein) (BF) show high degree of crystallinity in SAXS measurements (b) irrespective of preparation method (Methods 1 or 2). Fluorescence spectra (c) and integrated fluorescence intensities (d) show the presence of BF predominantly in the crystals but not in the supernatant (sup.).
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f6: Functionalization with fluorescent dyes.Crystals (cryst.) functionalized with (a) biotin (5-fluorescein) (BF) show high degree of crystallinity in SAXS measurements (b) irrespective of preparation method (Methods 1 or 2). Fluorescence spectra (c) and integrated fluorescence intensities (d) show the presence of BF predominantly in the crystals but not in the supernatant (sup.).

Mentions: Fluorescently labelled crystals carrying BF (Fig. 6a) could be efficiently formed by pre- or post-functionalization methods. SAXS curves measured from both samples indicate similar structure as pristine non-functionalized crystals (Fig. 6b). BF is very small (dmax ~1.5 nm) compared with the unit cell of the CCMV–avidin crystal and does not affect the structure of the functionalized crystal. BF has a fluorescence emission maximum at λem ~525 nm (Fig. 6c) making the functionalization straightforward to confirm by fluorescence measurements. Crystals were either pre- or post-functionalized in aqueous solution with an amount of BF equivalent to slightly <1 BF molecule per avidin, after which the functionalized crystals were separated from the solution and unbound BF by centrifugation. Both the supernatant (sup.; 80% of the sample volume) and the sediment (20% of the sample volume) were diluted to the same volume using concentrated NaCl solution to disassemble the crystals and facilitate fluorescence measurements. The integrated fluorescence intensities of pre-functionalized sediment and supernatant were 87% and 16%, respectively, of the pure BF sample fluorescence intensity. For post-functionalized samples, the respective values were 82% and 16% (Fig. 6d). This shows that the BF is readily absorbed in the CCMV-lattice regardless of how the BF functionalization is done.


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

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

Functionalization with fluorescent dyes.Crystals (cryst.) functionalized with (a) biotin (5-fluorescein) (BF) show high degree of crystallinity in SAXS measurements (b) irrespective of preparation method (Methods 1 or 2). Fluorescence spectra (c) and integrated fluorescence intensities (d) show the presence of BF predominantly in the crystals but not in the supernatant (sup.).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: Functionalization with fluorescent dyes.Crystals (cryst.) functionalized with (a) biotin (5-fluorescein) (BF) show high degree of crystallinity in SAXS measurements (b) irrespective of preparation method (Methods 1 or 2). Fluorescence spectra (c) and integrated fluorescence intensities (d) show the presence of BF predominantly in the crystals but not in the supernatant (sup.).
Mentions: Fluorescently labelled crystals carrying BF (Fig. 6a) could be efficiently formed by pre- or post-functionalization methods. SAXS curves measured from both samples indicate similar structure as pristine non-functionalized crystals (Fig. 6b). BF is very small (dmax ~1.5 nm) compared with the unit cell of the CCMV–avidin crystal and does not affect the structure of the functionalized crystal. BF has a fluorescence emission maximum at λem ~525 nm (Fig. 6c) making the functionalization straightforward to confirm by fluorescence measurements. Crystals were either pre- or post-functionalized in aqueous solution with an amount of BF equivalent to slightly <1 BF molecule per avidin, after which the functionalized crystals were separated from the solution and unbound BF by centrifugation. Both the supernatant (sup.; 80% of the sample volume) and the sediment (20% of the sample volume) were diluted to the same volume using concentrated NaCl solution to disassemble the crystals and facilitate fluorescence measurements. The integrated fluorescence intensities of pre-functionalized sediment and supernatant were 87% and 16%, respectively, of the pure BF sample fluorescence intensity. For post-functionalized samples, the respective values were 82% and 16% (Fig. 6d). This shows that the BF is readily absorbed in the CCMV-lattice regardless of how the BF functionalization is done.

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