Natural polyelectrolyte complex‐based pH‐dependent delivery carriers using alginate and chitosan

Abstract

The pH-dependent complexation behaviors of natural and counterionic polyelectrolyte complexes (PECs) without crosslinkers have been rarely studied. In this work, alginate (0.5-2.5 wt %) and chitosan (0.5-2 wt %) were combined to formulate turbid gel-like assemblies. The PEC was consisted of~100-μm-sized porous structure observed by scanning electron microscope images and electrostatic interactions inside the complex were newly formed characterized by Fourier transform infrared spectra. Based on visual monitoring and ultraviolet-visible absorption measurement, the complex maintained the gel-like structure under acidic, while the complex was more dissolved under becoming basic. As a demonstration of potential pH-dependent delivery, distinct release profiles of the complexes encapsulating rhodamine 6G (R6G) or doxorubicin, were observed when they were immersed in acidic, neutral, and basic medium. Within 2 h, 7.4, 35.4, and 73.7% of R6G were released under acidic, neutral, and basic condition, respectively, with reasons of degree of protonation or deprotonation of each natural polyelectrolyte at certain pH.

Self-Healing, Stretchable, Biocompatible, and Conductive Alginate Hydrogels through Dynamic Covalent Bonds for Implantable Electronics

“…In an aspect of storage for further applications, the shelf life of the hydrogels might be longer than at least one month because the hydrogels contain alginate backbone which is a major polymeric network and OEGCG as a crosslinker to interconnect their network, with strong anti-oxidant and anti-microbial effects. In general, the unmodified alginate hydrogels are totally degraded in vivo within one month [ 24 , 36 , 37 , 38 ]. In our system, the conjugation of boronic acid onto alginate might enhance the shelf-life of unmodified alginate due to the increase in relative molecular weight and inter-crosslinking density, and OEGCG can inhibit the growth of micro-organism [ 39 , 40 , 41 ].…”

“…Natural polymers, such as polysaccharides (alginate [ 14 ], chitosan [ 15 ], and hyaluronic acid [ 16 ]) and proteins (gelatin and silk) have generally been used to fabricate soft platforms such as hydrogels and aerogels [ 17 ] for medical applications because of their inherent renewability, nontoxicity, tissue compatibility [ 18 ], water solubility, biodegradability [ 19 ], microporosity [ 17 ] and moldability [ 20 ]. Due to these properties, natural polymers can be utilized as nontoxic, biocompatible conductive hydrogels that can be used for IEs, tissue scaffolds [ 21 , 22 ], and drug delivery systems [ 23 , 24 , 25 ]. Moreover, the structures of natural polymers can be modified with various functional groups, such as catechol, gallol, and boronic acid moieties with cis-diol, to improve the mechanical properties of hydrogels, required for various applications [ 26 , 27 , 28 ].…”

HClO/ClO–-Indicative Interpenetrating Polymer Network Hydrogels as Intelligent Bioactive Materials for Wound Healing

“…Alginate is a polysaccharide obtained by linear polymerization of α- l -guluronic acid, β- d -mannuronic acid, or alternating α- l -guluronic and β- d -mannuronic acids, forming an ionically cross-linked network in water. Sodium alginate has good stability and biocompatibility, which is required for pharmaceutical formulation excipients, and is therefore widely used in the field of biomedical materials. − Then the cross-linking RhB-AC network can be formed by aqueous radical polymerization of RhB-AC using a bifunctional monomer as the cross-linker. The ingredient TEMED can catalyze the production of free radicals by ammonium persulfate and initiate free radical polymerization.…”

Biomimetic scaffolds based on chitosan in bone regeneration. A review.

“…Due to its positive charge, chitosan has the ability to form complexes with negatively charged compounds, e.g. polylactide 37 , poly(glutamic acid) 38 , DNA 39,40 , collagen 41 , alginates [42][43][44] , hyaluronic acid [45][46][47] , pectin 48,49 and many others. The structure of chitosan, which is based on D-glucosamine andN-acetyl-D-glucosamine units, is similar to the structure of naturally occurring glycosaminoglycans (GAG).…”