In‐situ 2D bacterial crystal growth as a function of protein concentration: An atomic force microscopy study

Abstract

The interplay between protein concentration and (observation) time has been investigated for the adsorption and crystal growth of the bacterial SbpA proteins on hydrophobic fluoride‐functionalized SiO 2 surfaces. For this purpose, atomic force microscopy (AFM) has been performed in real‐time for monitoring protein crystal growth at different protein concentrations. Results reveal that (1) crystal formation occurs at concentrations above 0.08 µM and (2) the compliance of the formed crystal decreases by increasing protein concentration. All the crystal domains observed presented similar lattice parameters (being the mean value for the unit cell: a = 14.8 ± 0.5 nm, b = 14.7 ± 0.5 nm, γ = 90 ° ± 2). Protein film formation is shown to take place from initial nucleation points which originate a gradual and fast extension of the crystalline domains. The Avrami equation describes well the experimental results. Overall, the results suggest that protein‐substrate interactions prevail over protein–protein interactions. Research Highlights AFM enables to monitor protein crystallization in real‐time. AFM high‐resolution determines lattice parameters and viscoelastic properties. S‐layer crystal growth rate increases with protein concentration. Avrami equation models protein crystal growth.

Novel biodegradable and non-fouling systems for controlled-release based on poly(ε-caprolactone)/Quercetin blends and biomimetic bacterial S-layer coatings

“…14,15 This is the case of SbpA from Lysinibacillus sphaericus CCM2177, which presents a square (p4) lattice symmetry, a system that has quite extensively been characterized in literature so far. [16][17][18] Because of the large number of nanometric pores found along the S-layer structure, it can be hypothesized that the release of the drug from the polymeric matrix can be still conducted although to a lower rate.…”

Atomic Force Microscopy Meets Biophysics, Bioengineering, Chemistry, and Materials Science

“…AFM images revealed that lysine acetylation promoted al arger population of proteins in an open conformation,w hich playedarole in the autoimmune disease antiphospholipids yndrome. [52] Such measurementse nabledt he testing of theoreticalc rystal-growth models. The authors could demonstrate that proteins were incorporated within the lipid bilayer through their hydrophobic domains.…”

“…Moreno-Cencerrado et al followed the formation of 2D bacterial proteins crystals as a functiono ft ime for different protein concentrations (Figure 4). [52] Such measurementse nabledt he testing of theoreticalc rystal-growth models.…”

“…( Image taken from Ref [52]. Standard AFM (tapping mode) imaging is able to registerc overage of the fluoride-functionalized hydrophobic SiO 2 surfaces.…”

“…Experimental adsorption data can be used to check growth models and to optimize parametersf or proteinl ayer formation. ( Image taken from Ref [52]. with permission.…”