Structure of Protein Layers in Polyelectrolyte Matrices Studied by Neutron Reflectivity
- University of Alabama, Birmingham
- ORNL
Polyelectrolyte multilayer films obtained by localized incorporation of Green Fluorescent Protein (GFP) within electrostatically assembled matrices of poly(styrene sulfonate)/poly(allylamine hydrochloride) (PSS/PAH) via spin-assisted layer-by-layer growth were discovered to be highly structured, with closely packed monomolecular layers of the protein within the bio-hybrid films. The structure of the films was evaluated in both vertical and lateral directions with neutron reflectometry, using deuterated GFP as a marker for neutron scattering contrast. Importantly, the GFP preserves its structural stability upon assembly as confirmed by circular dichroism (CD) and in situ attenuated total reflection Fourier Transform Infrared spectroscopy (ATR-FTIR). Atomic force microscopy was complimented with X-ray reflectometry to characterize the external roughness of the biohybrid films. Remarkably, films assembled with a single GFP layer confined at various distances from the substrate exhibit a strong localization of the GFP layer without intermixing into the LbL matrix. However, partial intermixing of the GFP layers with polymeric material is evidenced in multiple-GFP layer films with alternating protein-rich and protein-deficient regions. We hypothesize that the polymer-protein exchange observed in the multiple-GFP layer films suggests the existence of a critical protein concentration which can be accommodated by the multilayer matrix. Our results yield new insights into the mechanism of GFP interaction with a polyelectrolyte matrix and open opportunities for fabrication of bio-hybrid films with well-organized structure and controllable function, a crucial requirement for advanced sensing applications.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Structural Molecular Biology (CSMB)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1030620
- Journal Information:
- Soft Matter, Vol. 7, Issue 24; ISSN 1744-683X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ATOMIC FORCE MICROSCOPY
DICHROISM
ELECTROLYTES
FABRICATION
FILMS
LAYERS
MATRICES
NEUTRON REFLECTORS
PROTEINS
REFLECTION
REFLECTIVITY
ROUGHNESS
SCATTERING
SPECTROSCOPY
SPIN
STABILITY
SUBSTRATES
Neutron Reflectivity
Layer-by-layer
Polyelectrolyte multilayer
Protein
Green Fluorescent Protein