Encapsulation of Activated Carbon into a Hollow-Type Spherical Bacterial Cellulose Gel and Its Indole-Adsorption Ability Aimed at Kidney Failure Treatment.

Toru Hoshi,Takao Aoyagi,Masahito Endo,Masashige Suzuki,Aya Hirai

doi:10.3390/pharmaceutics12111076

Abstract

For reducing side effects and improvement of swallowing, we studied the encapsulation of activated carbon formulations with a hollow-type spherical bacterial cellulose (HSBC) gel using two kinds of encapsulating methods: Methods A and B. In Method A, the BC gelatinous membrane was biosynthesized using Komagataeibacter xylinus (K. xylinus) at the interface between the silicone oil and cell suspension containing activated carbon. In Method B, the bacterial cellulose (BC) gelatinous membrane was formed at the interface between the cell suspension attached to the alginate gel containing activated carbon and the silicone oil. After the BC gelatinous membrane was biosynthesized by K. xylnus, alginate gel was removed by soaking in a phosphate buffer. The activated carbon encapsulated these methods could neither pass through the BC gelatinous membrane of the HSBC gel nor leak from the interior cavity of the HSBC gel. The adsorption ability was evaluated using indole, which is a precursor of the uremic causative agent. From curve-fitting, the adsorption process followed the pseudo-first-order and intra-particle diffusion models, and the diffusion of the indole molecules at the surface of the encapsulated activated carbon within the HSBC gel was dominant at the initial stage of adsorption. It was observed that the adsorption of the encapsulated activated carbon by the intraparticle diffusion process became dominant with longer adsorption times.

Highlights

The kidney acts as a filter for all of the fluids in our body
Where the cell suspension was in contact with the bottom of a 96-well plate composed of polypropylene (PP), the bacterial cellulose (BC) gelatinous membrane was thin
Cellulose was likely to be biosynthesized on the side of the silicone oil side that had a higher oxygen permeability than PP, resulting in the BC gelatinous membrane being thicker

Summary

Introduction

The kidney acts as a filter for all of the fluids in our body. Kidney failure is characterized by an accumulation of human metabolic products (uremic toxins) in the blood as it is impossible to eliminate them [1]. AST-120 (KREMEZIN®) is an orally-administered spherical carbon adsorbent consisting of porous carbon particles that are 0.2–0.4 mm in diameter and insoluble in water and that can adsorb various small molecules, including uremic toxins. AST-120 treats uremic symptoms and prolongs the time to initiation of dialysis in patients with progressive CKD [3]. Carbon adsorbents such as AST-120 and activated carbon powder are difficult to handle for patients [4]. These oral carbon absorbents have disadvantages, such as a gritty feeling, stickiness in the mouth and the throat in swallowing, large tablet size, and large dosage. There is a limit to the possible reduction of the particle size of carbon adsorbents; it is necessary to develop a carbon adsorbent drug that is easy to swallow and effective at a small dosage

Methods

Results

Conclusion