Dual‐responsive semi‐interpenetrating network beads based on calcium alginate/poly(N‐isopropylacrylamide)/poly(sodium acrylate) for sustained drug release

Abstract

To improve the mechanical strength of natural hydrogels and to obtain a sustained drug-delivery device, temperature-/pH-sensitive hydrogel beads composed of calcium alginate (Ca-alginate) and poly(N-isopropylacrylamide) (PNIPAAm) were prepared in the presence of poly(sodium acrylate) (PAANa) with ultrahigh molecular weight (M g ! 1.0 Â 10 7 ) as a strengthening agent. The influence of PAANa content on the properties, including the beads stability, swelling, and drug-release behaviors, of the hydrogels was evaluated. Scanning electron microscopy and oscillation experiments were used to analyze the structure and mechanical stability of the hydrogel beads, respectively. The results show that stability of the obtained Ca-alginate/PNIPAAm hydrogel beads strengthened by PAANa the alginate/ poly(N-isopropyl acrylamide) hydrogel bead (SANBs) was significantly improved compared to that of the beads without PAANa (NANBs) at pH 7.4. The swelling behavior and drug-release capability of the SANBs were markedly dependent on the PAANa content and on the environmental temperature and pH. The bead sample with a higher percentage of PAANa exhibited a lower swelling rate and slower drug release. The drug release profiles from SANBs were further studied in simulated intestinal fluid, and the results demonstrated here suggest that SANBs could serve as a potential candidate for controlled drug delivery in vivo.

Glucose‐Triggered Insulin Release from Fe3+‐Cross‐linked Alginate Hydrogel: Experimental Study and Theoretical Modeling

“…Alginate polymer can be cross‐linked with multivalent metal cations (Ca 2+ cations are the most utilized cross‐linkers) producing a hydrogel capable of encapsulation and then controlled release of various biomolecules, including proteins/enzymes, DNA, and other (bio)molecular species, for example, drugs . The Ca 2+ ‐cross‐linked alginate hydrogel has been used for continuous slow release (leakage) of the entrapped species.…”

“…[20,21] Alginate polymer can be cross-linked with multivalent metal cations (Ca 2 + cations are the most utilized cross-linkers) producingahydrogel capable of encapsulationa nd then controlledr elease of various biomolecules, including proteins/enzymes, [22][23][24][25][26] DNA, [27,28] and other (bio)molecular species, for example,d rugs. [29,30] The Ca 2 + -cross-linkeda lginate hydrogel has been used for continuous slow release (leakage) of the entrapped species. In order to trigger the releasep rocess by external signals, the alginatepolymer can be cross-linked with Fe 3 + cations, [31,32] which can be chemically or electrochemically reduced to Fe 2 + ,t he latter with no cross-linkingf unctionality for alginate; see Figure SI-1i nt he Supporting Information for illustration.…”

Diffusion of Oligonucleotides from within Iron‐Cross‐Linked, Polyelectrolyte‐Modified Alginate Beads: A Model System for Drug Release

“…Generally, Fe 3+ cross‐linking can be reduced by chemical or electrochemical means . However, polyelectrolyte dopants, such as PAH here, introduced during bead synthesis can have the opposite effect of stabilizing the beads and decreasing the mobility of the loaded material . This stabilizing effect is particularly pronounced when the negatively charged alginate polymer forms a complex with a positively charged polyelectrolyte (e.g., polyethyleneimine, polylysine, or polyallylamine; the latter was used in the present study).…”

Antimicrobial loading into and release from poly(ethylene glycol)/poly(acrylic acid) semi‐interpenetrating hydrogels

“…Here, we introduce electrostatic charge into a PEG gel by blending high‐molecular‐weight poly(acrylic acid) (PAA) with PEG diacrylate (PEGDA) to form a semi‐IPN gel. Semi‐IPN gels have been previously used to control drug release . In contrast to this previous work, we investigate how electrostatic interactions can both enable post‐synthesis antibiotic loading and control antibiotic release in different environments.…”