Encapsulation of E. coli in biomimetic and Fe3O4-doped hydrogel: structural and viability analyses

Abstract

The current study reports the modification of prokaryotic microorganism through a single-layer technique by using different polyanions/cations and doping with magnetic (FeO) nanoparticles. Briefly, individual Escherichia coli cells were encapsulated through deposition of 1% sodium alginate as first layer followed by depositing precipitate layers of calcium chloride, disodium hydrogen phosphate, and FeO nanoparticles. Surface and cross sectional analysis of modified E. coli cells by field emission scanning electron microscope (FE-SEM) confirmed the synthesis of varying sizes of artificial shells around the microbial cells while the deposition of FeO nanoparticles was confirmed by transmission electron microscope (TEM). Thermogravimetric analysis (TGA) showed the deposition of 58 wt% of FeO nanoparticles on E. coli cell surface. Chemical structure analysis by Fourier transform infrared (FTIR) spectroscopy confirmed the presence of characteristic functional groups of deposited reagents in the hydrogel capsule. Zeta potential analysis of hydrogel capsule showed moderate stability with a surface charge of - 21 mV. Growth and viability analysis by Alamar Blue assay indicated marked increase in the reduction of resazurin blue (> 100%) by the modified E. coli indicating their viability. The movement and control of magnetized E. coli cells were manipulated using external permanent magnetic field as observed with optical microscope images. The surface-modified cells can find potential applications in bioremediation, biodegradation, and catalysis and can be used as biosorbents.

Quantum-Efficiency Enhancement and Mechanical Responsiveness of Solid-State Photoluminescence Materials Based on Uniaxial Cellulose Nanocrystal Arrays in Flexible Polymer via Assembly-Induced Emission

“…Table 1 shows the zeta-potential of CNC in the suspension with poly (vinyl alcohol) (PVA) with different ratios, which indicated that neat CNC suspension owned an extremely high zeta potential of -72.2 mV. As the PVA percentage increased, the zeta potential decreased but remained at a high level of > 30 mV, which indicated the suspensions were still highly stable (Kiprono et al 2018). In order to eliminate the chiral structure, the zeta potential of the CNC dispersion should not be too high to achieve the uniaxial assembly with higher orientation.…”

Fabrication of nanocomposites and hybrid materials using microbial biotemplates

“…polyanions/cations, biopolymers, and magnetic (Fe 3 O 4 ) nanoparticles without compromising their viability [12], thus supporting the development of core-shell hybrid structures and composites. Microbes not only can perform biological functions as individuals, but these also can replicate and be readily distributed and expanded to form functional colonies.…”

Cell-based biocomposite engineering directed by polymers

“…27,28 Magnetic functionalization of cells was also realized by decorating Fe 3 O 4 nanoparticles onto the cell surface by using the polymer-directed strategy. 29,30,129,206,207 PDA was employed as an interlayer for subsequent combination of magnetic iron oxide nanoparticles modified with carboxylic acid. 129 In addition, carbon materials were also coupled with cells under polymer assistance.…”