pH-Responsive Cellulose-Based Microspheres Designed as an Effective Oral Delivery System for Insulin

Abstract

Functional modified cellulose microsphere (CMs) materials exhibit great application potential in drug various fields. Here, we designed pH-responsive carboxylated cellulose microspheres (CCMs) by the citric/hydrochloric acid hydrolysis method to enhance oral bioavailability of insulin by a green route. The CMs were high purity cellulose that dissolved and regenerated from a green solvent by the green sol−gel method. The prepared microspheres were characterized by spectroscopic techniques, such as field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrum (FT-IR), Xray diffraction (XPS), etc. The spherical porous structure and carboxylation of cellulose were confirmed by FESEM and FT-IR, respectively. Insulin was loaded into the CCMs by electrostatic interactions, and the insulin release was controlled through ionization of carboxyl groups and proton balance. In vitro insulin release profiles demonstrated the suppression of insulin release in artificial gastric fluid (AGF), while a significant increase at artificial intestinal fluid (AIF) was observed. The insulin release profile was fitted in Korsmeyer−Peppas kinetic model, and insulin release was governed by the Fickian diffusion mechanism. The stability of the secondary structure of insulin was studied by dichroism circular. Excellent biocompatibility and no cytotoxicity of designed CCMs cast them as a potential oral insulin carrier.

pH-Responsive Capsule Polymer Particles Prepared by Interfacial Photo-Cross-Linking: Effect of the Alkyl Chain Length of the pH-Responsive Monomer

“…Notably, control of the pH-responsiveness in the weakly acidic region is important for drug delivery systems because the tumor microenvironment exhibits a lower pH than that of the normal tissue due to the accumulation of lactic acid. , Furthermore, endosomes and lysosomes exhibit weakly acidic conditions (4.5–6.0) . Notably, oral delivery to the stomach is another potential application. − We are currently elucidating the size control of these capsules for these drug delivery applications, and the results will be reported in the near future.…”

Advances in Nanotechnology for Enhancing the Solubility and Bioavailability of Poorly Soluble Drugs

“…116,117 Avoiding Early Metabolism of Drugs Nano drug delivery systems can exploit the size difference between drugs and digestive enzymes to fabricate porous inorganic nanoparticle carriers, safeguarding the drug from enzymatic degradation. 118,119 Additionally, these systems can utilize the hydrophobic interactions between the nanocarriers and digestive enzymes to shield the drug from 120,121 Thermosensitive and biodegradable targeted nanoparticle hydrogels remain in a liquid state at room temperature but transform into a gel at body temperature. This conversion creates a depot system capable of sustained drug release over extended periods, enhancing in vivo retention and significantly improving clinical therapeutic efficacy.…”

Muco-Adhesive and Muco-Penetrative Formulations for the Oral Delivery of Insulin

“…Gong et al 30 designed pH-responsive carboxylated cellulose microspheres (CCMs) to enhance the oral bioavailability of insulin. The CCMs were prepared using the citric/hydrochloric acid hydrolysis method through the ionization of the carboxyl group, showing a controlled release of insulin in the bloodstream.…”