3D Porous Collagen Matrices—A Reservoir for In Vitro Simultaneous Release of Tannic Acid and Chlorhexidine

Abstract

The treatment of wounds occurring accidentally or as a result of chronic diseases most frequently requires the use of appropriate dressings, mainly to ensure tissue regeneration/healing, at the same time as treating or preventing potential bacterial infections or superinfections. Collagen type I-based scaffolds in tandem with adequate antimicrobials can successfully fulfill these requirements. In this work, starting from the corresponding hydrogels, we prepared a series of freeze-dried atelocollagen type I-based matrices loaded with tannic acid (TA) and chlorhexidine digluconate (CHDG) as active agents with a broad spectrum of antimicrobial activity and also as crosslinkers for the collagen network. The primary aim of this study was to design an original and reliable algorithm to in vitro monitor and kinetically analyze the simultaneous release of TA and CHDG from the porous matrices into an aqueous solution of phosphate-buffered saline (PBS, pH 7.4, 37 °C) containing micellar carriers of a cationic surfactant (hexadecyltrimethylammonium bromide, HTAB) as a release environment that roughly mimics human extracellular fluids in living tissues. Around this central idea, a comprehensive investigation of the lyophilized matrices (morpho-structural characterization through FT-IR spectroscopy, scanning electron microscopy, swelling behavior, resistance against the collagenolytic action of collagenase type I) was carried out. The kinetic treatment of the release data displayed a preponderance of non-Fickian–Case II diffusion behavior, which led to a general anomalous transport mechanism for both TA and CHDG, irrespective of their concentrations. This is equivalent to saying that the release regime is not governed only by the gradient concentration of the releasing components inside and outside the matrix (like in ideal Fickian diffusion), but also, to a large extent, by the relaxation phenomena of the collagen network (determined, in turn, by its crosslinking degree induced by TA and CHDG) and the dynamic capacity of the HTAB micelles to solubilize the two antimicrobials. By controlling the degree of physical crosslinking of collagen with a proper content of TA and CHDG loaded in the matrix, a tunable, sustainable release profile can be obtained.

Dialdehyde Starch as a Cross-Linking Agent Modifying Fish Collagen Film Properties

“…Spectra of native collagen films and collagen films with DAS addition are presented in Figures 1 and 2, respectively. The following characteristic bands for collagen were found on the spectra: Amide A bands at about 3300 cm −1 , Amide B bands at about 3080 cm −1 , asymmetrical stretch of -CH 2 bands at about 2930 cm −1 , Amide I at about 1630 cm −1 , Amide II at about 1540 cm −1 , bend of -CH 2 bands at about 1450 cm −1 , symmetrical stretch of COO-at 1379-1397 cm −1 , bands corresponding to in-plane OH (phenol) bending at 1337-1338 cm −1 , Amide III band at 1235-1237 cm −1 , and stretch of C-O and asymmetrical and symmetrical stretch of C-O-C bands at 1080 and 1030 cm −1 , respectively [34][35][36][37]. Wavenumbers for the mentioned IR characteristic bands for collagen samples are presented in Table 2.…”

Preparation and Characterization of a Photo-Crosslinked Methacryloyl-Collagen Composite Film to Promote Corneal Nerve Regeneration via Surface Grafting of Taurine Molecules

“…The ColMA-Tr film's taurine release was tested in PBS with a pH of 7.4 and a constant temperature of 37 • C. The 2 mL of drug release solution was removed and put away at various intervals, and 2 mL of new PBS supplement solution was added. After that, a UV-2800A UV-visible spectrophotometer (China) was used to examine the amount of taurine present in the release solution [44]. Five parallel experiments were run by each group.…”