Mucoadhesive and Antimicrobial Allantoin/β Cyclodextrins-Loaded Carbopol Gels as Scaffolds for Regenerative Medicine

Abstract

Allantoin and its β-cyclodextrin and hydroxypropyl-β-cyclodextrin inclusion complexes 1:1 have been used to prepare carbopol-based mucoadhesive gels. The gelation process occurred by adjustment with glycerol 10% in the presence of triethanolamine. The structural features induced by the presence of allantoin and the corresponding β-cyclodextrins inclusion complexes have been first investigated by infrared spectroscopy highlighting strong interactions within the gels network and ideal crosslinks for the self-healing behavior. The hydrophilicity of the gels was investigated by the determination of the surface tension parameters and the free energy of hydration. The interfacial free energy values indicated prolonged biocompatibility with blood. The gels-water molecule interactions in terms of sorption, permeability, and diffusion coefficients were evaluated by dynamic vapor sorption analysis. The self-assembly process through intermolecular H-bonding, the high hydrophilicity, the mechanical performance, the hydrolytic stability in simulated biological media, the biocompatibility with normal human dermal fibroblast (NHDF) cells, the mucoadhesivity and antimicrobial activity on selected microorganism species (S. Aureus and C. albicans) of the allantoin-based gels recommend them as promising scaffold alternatives in regenerative medicine.

Keywords: antibacterial; interfacial energy; mucoadhesion; tissue engineering scaffolds; β-cyclodextrin/allantoin inclusion complexes.

Figure 1

Carbonyl and amide II spectral regions of H1, H2, H1Al, and H2Al samples (a) and the comparative spectra of allantoin, β-CD, HP-β-CD, and Carbopol 934 (b).

Figure 2

The C-H (a) and carbonyl, amide II (b) regions of β-CD, HP-β-CD and their inclusion complexes with allantoin (1:1).

Figure 3

Carbonyl, amide II (a), and C-O-C (b) spectral regions for P1–P4 hydrogel samples.

Figure 4

The sorption/desorption isotherms of studied hydrogels: a—H1, H2, H1Al, and H2Al samples; b—P1, P2, P3, and P4 samples.

Figure 5

Compression tests of the samples at 20% compressive strains: (a)—H1, (b)—H2, (c)—H1Al, and (d)—H2Al.

Figure 6

The dependence of Force/compressive strain% of the samples: (a)—H1, (b)—H2, (c)—H1Al, and (d)—H2Al.

Figure 7

Compression tests of the samples at 20% compressive strains: (a)—P1, (b)—P2, (c)—P3, and (d)—P4.

Figure 8

The dependence of Force/compressive strain % of the samples: (a)—P1, (b)—P2, (c)—P3, and (d)—P4.

Figure 9

IR subtracted spectra of the H1-(a), H2-(b), H1Al-(c), and H2Al-(d) after 24 h, 48 h, and 72 h immersion in a complete cell medium.

Figure 10

IR subtracted spectra of the P1-(a), P2-(b), P3-(c), and P4-(d) after 24 h, 48 h, and 72 h immersion in a complete cell medium.

Figure 11

The cell viability on the NHDF cell line of the studied gels.

Figure 12

The appearance of the fibroblasts after 48 h incubation with gels: H1, H1Al and P1 in comparison with the control (CTRL) sample.

Figure 13

Bioadhesionand mucoadhesiontests for studied formulations.

Figure 14

Antibacterial activity of tested compounds (H1–H2 and P1–P4) against S. aureus ATCC 25923.