Porous 3D Prussian blue/cellulose aerogel as a decorporation agent for removal of ingested cesium from the gastrointestinal tract

Abstract

In the present study, we successfully synthesized a porous three-dimensional Prussian blue-cellulose aerogel (PB-CA) composite and used it as a decorporation agent for the selective removal of ingested cesium ions (Cs⁺) from the gastrointestinal (GI) tract. The safety of the PB-CA composite was evaluated through an in vitro cytotoxicity study using macrophage-like THP-1 cells and Caco-2 intestinal epithelial cells. The results revealed that the PB-CA composite was not cytotoxic. An adsorption study to examine the efficiency of the decorporation agent was conducted using a simulated intestinal fluid (SIF). The adsorption isotherm was fitted to the Langmuir model with a maximum Cs⁺ adsorption capacity of 13.70 mg/g in SIF that followed pseudo-second-order kinetics. The PB-CA composite showed excellent stability in SIF with a maximum Cs⁺ removal efficiency of 99.43%. The promising safety toxicology profile, remarkable Cs⁺ adsorption efficacy, and excellent stability of the composite demonstrated its great potential for use as an orally administered drug for the decorporation of Cs⁺ from the GI tract.

Figure 1

(A) Schematic diagram of the action of PB-CA in the gastrointestinal tract. (B) Illustrative morphology of PB-CA composite. (C) Cesium adsorption mechanism of PB.

Figure 2

Fabrication and characterization of PB-CA. (A) Schematic diagram of the fabrication of PB-CA composite, (B) XRD patterns of CA and PB-CA composite, (C) FT-IR spectra of CA and PB-CA composite, (D) BET isotherm of PB-CA composite (inset: pore size distribution of PB-CA composite), (E) XPS survey spectra of CA and PB-CA composite, (F) C 1s spectra of PB-CA composite, and (G) O 1s spectra of PB-CA composite.

Figure 3

SEM images of the PB-CA composite. (A) Surface morphology, (B,C) inner morphology at different magnifications, and (D) cross section morphology.

Figure 4

Cell viability analysis of PB and PB-CA (direct and indirect mechanisms). (A) Cytotoxicity of PB and PB-CA in macrophage-like THP-1 cells (solid line) and Caco-2 intestinal epithelial cells (dashed line). (B) Optical images of macrophage-like THP-1 cells treated by PB NPs (upper panel) and PB-CA (lower panel). (C) Optical images of Caco-2 intestinal epithelial cells treated by PB NPs (upper panel) and PB-CA (lower panel). (D) Potential of ROS generation of PB and PB-CA measured by DCFH-DA assay. (E) Protein corona binding affinity assay of PB and PB-CA (the data are expressed as adsorbed protein levels). (F) The change of pH before and after incubation of PB and PB-CA in various media.

Figure 5

Adsorption stability test of PB-CA. (A) UV spectra of PB-CA treated in SGF (upper panel) and SIF (lower panel) for 24 h (the insets present optical microscopy images to show the stability behavior of PB NPs and PB-CA in SGF (upper panel) and SIF (lower panel) treated for 24 h). (B) UV spectra of PB-CA after gamma ray irradiated at 0 kGy (upper panel), 6 kGy (middle panel), and 60 kGy (lower panel) (the insets represent optical microscopy images to show the behavior of PB-CA after gamma ray irradiation at 0 kGy (upper panel), 6 kGy (middle panel), and 60 kGy (lower panel)).

Figure 6

Cesium adsorption isotherm and kinetics studies of PB-CA. (A) Cesium adsorption isotherms fitted with Langmuir and Freundlich models in DW. (B) Cesium adsorption isotherms fitted with Langmuir and Freundlich models in SIF. (C) Cesium adsorption kinetics of PB-CA in DW fitted with pseudo-second order kinetics model. (D) Cesium adsorption kinetics of PB-CA in SIF fitted with pseudo-second order kinetics model.

Figure 7

Cesium removal efficiency in DW, SGF, and SIF after 1 and 10 min (10 mL of cesium solution with 50 mg of PB-CA).

Figure 8

Intra-particle diffusion model of cesium adsorption. (A) Diffusion studies of cesium into PB-CA from DW. (B) Diffusion studies of cesium into PB-CA from SIF (dashed lines represent external mass transfer, solid lines represent intra-particle diffusion, and dotted lines represent saturation of cesium ions in PB-CA). (C) Schematic diagrams of cesium adsorption into the PB-CA from DW. (D) Schematic diagrams of cesium adsorption into the PB-CA from SIF (cesium and potassium concentrations are 0.1 and 2000 ppm, respectively).

Figure 9

Cesium distribution on PB-CA after adsorption. (A) SEM image of the cryo-fractured PB-CA. (B) EDS mapping of iron. (C) EDS mapping of cesium. (D) EDS mapping of iron-cesium-overlay.