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. 2023 Jun 16;15(6):1749.
doi: 10.3390/pharmaceutics15061749.

Modified Sulfanilamide Release from Intelligent Poly(N-isopropylacrylamide) Hydrogels

Ana Dinić  1 , Vesna Nikolić  1 , Ljubiša Nikolić  1 , Snežana Ilić-Stojanović  1 , Stevo Najman  2   3 , Maja Urošević  1 , Ivana Gajić  1
Affiliations

Modified Sulfanilamide Release from Intelligent Poly(N-isopropylacrylamide) Hydrogels

Ana Dinić et al. Pharmaceutics. .

Abstract

The aim of this study was to examine homopolymeric poly(N-isopropylacrylamide), p(NIPAM), hydrogels cross-linked with ethylene glycol dimethacrylate as carriers for sulfanilamide. Using FTIR, XRD and SEM methods, structural characterization of synthesized hydrogels before and after sulfanilamide incorporation was performed. The residual reactants content was analyzed using the HPLC method. The swelling behavior of p(NIPAM) hydrogels of different crosslinking degrees was monitored in relation to the temperature and pH values of the surrounding medium. The effect of temperature, pH, and crosslinker content on the sulfanilamide release from hydrogels was also examined. The results of the FTIR, XRD, and SEM analysis showed that sulfanilamide is incorporated into the p(NIPAM) hydrogels. The swelling of p(NIPAM) hydrogels depended on the temperature and crosslinker content while pH had no significant effect. The sulfanilamide loading efficiency increased with increasing hydrogel crosslinking degree, ranging from 87.36% to 95.29%. The sulfanilamide release from hydrogels was consistent with the swelling results-the increase of crosslinker content reduced the amount of released sulfanilamide. After 24 h, 73.3-93.5% of incorporated sulfanilamide was released from the hydrogels. Considering the thermosensitivity of hydrogels, volume phase transition temperature close to the physiological temperature, and the satisfactory results achieved for sulfanilamide incorporation and release, it can be concluded that p(NIPAM) based hydrogels are promising carriers for sulfanilamide.

Keywords: N-isopropylacrylamide; characterization; release kinetics; sulfanilamide; swelling kinetics; thermosensitive hydrogels.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
The chemical structure of sulfanilamide.
Figure 2
Figure 2
The HPLC chromatograms and UV spectra of: (a) monomer NIPAM and (b) crosslinker EGDM.
Figure 3
Figure 3
The swelling profiles of p(NIPAM) hydrogels at 20 ± 1 °C in the solution with the pH value of (a) 2.2 and (b) 7.4.
Figure 4
Figure 4
The swelling profiles of p(NIPAM) hydrogels at 37 ± 1 °C in the solution with the pH value of (a) 2.2 and (b) 7.4.
Figure 5
Figure 5
Dependence of the swelling degree of p(NIPAM) hydrogels, α, on the temperature.
Figure 6
Figure 6
1H-NMR spectrum of sulfanilamide.
Figure 7
Figure 7
FTIR spectra of: (a) sulfanilamide, (b) p(NIPAM) hydrogel 2.5 mol%, and (c) p(NIPAM) hydrogel 2.5 mol% with incorporated sulfanilamide.
Figure 8
Figure 8
Diffractograms of (a) sulfanilamide, (b) p(NIPAM) with 1.5 and 2.5 mol% of crosslinker, and p(NIPAM) with 1.5 mol% crosslinker and incorporated sulfanilamide.
Figure 9
Figure 9
SEM micrographs of p(NIPAM) hydrogels: (a) 1.5 mol% (1000×), (b) 2.5 mol% (1000×), (c) 1.5 mol% with incorporated sulfanilamide (500×), and (d) 2.5 mol% with incorporated sulfanilamide (500×).
Figure 10
Figure 10
HPLC chromatogram of sulfanilamide.
Figure 11
Figure 11
Released sulfanilamide content at 37 ± 1 °C from p(NIPAM) hydrogels at: (a) pH = 2.2 and (b) pH = 7.4.
Figure 12
Figure 12
Released sulfanilamide content at 20 ± 1 °C from p(NIPAM) hydrogels at: (a) pH = 2.2 and (b) pH = 7.4.
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