Novel ionically crosslinked acrylamide-grafted poly(vinyl alcohol)/sodium alginate/sodium carboxymethyl cellulose pH-sensitive microspheres for delivery of Alzheimer's drug donepezil hydrochloride: Preparation and optimization of release conditions

2014 ◽  
Vol 44 (2) ◽  
pp. 431-442 ◽  
Author(s):  
Emine Bulut ◽  
Oya Şanlı
2021 ◽  
Vol 12 (4) ◽  
pp. 4770-4779

Currently, self-healing hydrogels prepared from the green process have been studied for various applications, especially in the biomedical field. This work fabricated the self-healing hydrogel based on sodium carboxymethyl cellulose/poly(vinyl alcohol)/montmorillonite by acidifying the mixture with citric acid. SEM measurements showed well-dispersed montmorillonite in the hydrogels. Cytotoxicity values >100% were seen with montmorillonite added, which indicated cell growth and no cell toxicity. Montmorillonite addition not only reinforced the networks but also improved self-healing ability. The tensile strength of the original uncut hydrogel with montmorillonite (P1C8M1) was 61 kPa, whereas the healed hydrogel showed 57 kPa. The hydrogel healed completely within 10 days, without any cracks, i.e., a 93% healing efficiency, or higher than the ~60% of the non-reinforced hydrogel. This confirmed strong hydrogen bond formation between the polymer and montmorillonite. The self-healing ability of this non-toxic hydrogel, reinforced with montmorillonite, makes it valuable for use in biomedical fields.


Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2381
Author(s):  
Katarzyna Bialik-Wąs ◽  
Ewelina Królicka ◽  
Dagmara Malina

Here, we report on studies on the influence of different crosslinking methods (ionic and chemical) on the physicochemical (swelling ability and degradation in simulated body fluids), structural (FT-IR spectra analysis) and morphological (SEM analysis) properties of SA/PVA hydrogels containing active substances of natural origin. First, an aqueous extract of Echinacea purpurea was prepared using a Soxhlet apparatus. Next, a series of modified SA/PVA-based hydrogels were obtained through the chemical crosslinking method using poly(ethylene glycol) diacrylate (PEGDA, Mn = 700 g/mol) as a crosslinking agent and, additionally, the ionic reaction in the presence of a 5% w/v calcium chloride solution. The compositions of SA/PVA/E. purpurea-based hydrogels contained a polymer of natural origin—sodium alginate (SA, 1.5% solution)—and a synthetic polymer—poly(vinyl alcohol) (PVA, Mn = 72,000 g/mol, 10% solution)—in the ratio 2:1, and different amounts of the aqueous extract of E. purpurea—5, 10, 15 or 20% (v/v). Additionally, the release behavior of echinacoside from the polymeric matrix was evaluated in phosphate-buffered saline (PBS) at 37 °C. The results indicate that the type of the crosslinking method has a direct impact on the release profile. Consequently, it is possible to design a system that delivers an active substance in a way that depends on the application.


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