Cytocompatibility, Antimicrobial and Antioxidant Activity of a Mucoadhesive Biopolymeric Hydrogel Embedding Selenium Nanoparticles Phytosynthesized by Sea Buckthorn Leaf Extract

Abstract

Phytosynthesized selenium nanoparticles (SeNPs) are less toxic than the inorganic salts of selenium and show high antioxidant and antibacterial activity. Chitosan prevents microbial biofilm formation and can also determine microbial biofilm dispersal. Never-dried bacterial nanocellulose (NDBNC) is an efficient carrier of bioactive compounds and a flexible nanofibrillar hydrophilic biopolymer. This study aimed to develop a selenium-enriched hydrogel nanoformulation (Se-HNF) based on NDBNC from kombucha fermentation and fungal chitosan with embedded biogenic SeNPs phytosynthesized by an aqueous extract of sea buckthorn leaves (SbLEx)—SeNPsSb—in order to both disperse gingival dysbiotic biofilm and prevent its development. We determined the total phenolic content and antioxidant activity of SbLEx. Liquid chromatography–mass spectrometry (LC-MS) and high-performance liquid chromatography (HPLC) were used for the identification of polyphenols from SbLEx. SeNPsSb were characterized by transmission electron microscopy–energy-dispersive X-ray spectroscopy (TEM-EDX), dynamic light scattering (DLS), zeta potential, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) in small- and wide-angle X-ray scattering (SAXS and WAXS). The hydrogel nanoformulation with embedded SeNPsSb was characterized by SEM, FTIR, XRD, rheology, mucin binding efficiency, contact angle and interfacial tension measurements. We also assessed the in vitro biocompatibility, antioxidant activity and antimicrobial and antibiofilm potential of SeNPsSb and Se-HNF. TEM, DLS and SAXS evidenced polydisperse SeNPsSb, whereas FTIR highlighted a heterogeneous biocorona with various biocompounds. The contact angle on the polar surface was smaller (52.82 ± 1.23°) than that obtained on the non-polar surface (73.85 ± 0.39°). The interfacial tension was 97.6 ± 0.47 mN/m. The mucin binding efficiency of Se-HNF decreased as the amount of hydrogel decreased, and the SEM analysis showed a relatively compact structure upon mucin contact. FTIR and XRD analyses of Se-HNF evidenced an interaction between BNC and CS through characteristic peak shifting, and the rheological measurements highlighted a pseudoplastic behavior, 0.186 N adhesion force and 0.386 adhesion energy. The results showed a high degree of cytocompatibility and the significant antioxidant and antimicrobial efficiency of SeNPsSb and Se-HNF.

The Clothes Matter—Exploiting Agronomical Functions of Trichogenic Selenium Nanoparticles Sharing Activities with Biological Systems Wherein (Were) Formed

“…The literature of SeNPs characterization using SAXS is scarce, suggesting an available innovative niche at the crossroads of these two directions. In a first example from our group, SAXS performed on SeNPs phytosynthesized using sea buckthorn leaf extract evidenced a polydisperse distribution of SeNPs with four main population between 9 and 60 nm and also suggested, in correlation with WAXS analysis, that the SeNPs nanograins are clusters of 3 nm crystallites, with SAXS peaks in the scattering wavevector q values ranges of 0.1-0.7 nm −1 (2θ between 0.2 and 1 • ) corresponding to 9, 12, 18, 24, 27 and 54 nm nanoparticle diameters [138]. In another study, spherical red SeNPs with a mean size of 45 nm were obtained by the reduction of Na 2 SeO 3 with L-cysteine and further stabilized with 29 kDa polyvinylpyrrolidone [157].…”

“…This peak was accompanied by small crystalline peaks at 19.18 , suggesting a strong reduction of initial sodium selenite. The crystallite sizes of these SeNPs were evaluated by WAXS to be around 3.5, 8.9, 6.7 and 12.3 nm with a clear pattern toward a 3 nm core crystallite, which was confirmed by a similar pattern in SAXS with SeNPs crystallites clusters around 9, 12, 18, 24, 27 and 54 nm [138], as further detailed.…”

“…The SeNPs appeared to be semi-crystalline with an amorphous peak centered around 25 • and additional crystalline peaks comparable with the main peaks of Na 2 SeO 3 . A strong amorphous peak was also found around the 2θ angle of 25.70 • in SeNPs reduced with sea buckthorn leaf extract, which was semi-crystalline but predominantly amorphous due to a bio-corona with a 36% crystallinity degree [138]. This peak was accompanied by small crystalline peaks at 19.18 , suggesting a strong reduction of initial sodium selenite.…”

“…The shape, size, stability and chemical structure of the biocorona are some of the parameters that were frequently reported in studies of SeNPs. These NP characteristics are often analyzed in correlation with their stabilizing biomolecules, which are mainly proteins and amino acids [93,109,126,136,137] or proteins and polysaccharides [110,112,138]. The main techniques used for NP characterization are inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES) and colorimetric methods for quantification, single-particle mode ICP-MS (SP-ICP-MS), UV-Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray fluorescence analysis (XFA), electron energy-loss spectroscopy (EELS) for selenium detection, X-ray absorption (XANES and EXAFS) for oxidation state, X-ray diffraction (XRD) in small and wide-angle scattering (SAXS and WAXS), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS) and zeta potential, analytical centrifugation methods such as differential centrifugal sedimentation (DCS) [139], isothermal titration calorimetry, surface tension and contact angle (which can provide information on the hydrophobicity/hydrophilicity of the system and the interaction of SeNPs with the solvent), Fourier-transform infrared (FTIR) and Raman spectroscopy, sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE) electrophoresis for the identification of proteins capping the NPs, and mass spectrometry coupled with chromatography for the identification of biomolecules from bio-corona.…”

“…For other crystalline SeNPs derived from Na 2 SeO 3 reduced with T. harzianum extract, only the diffraction planes of SeNPs assigned to oval crystalline SeNPs were described [114], while the apparent 2θ angles assigned to trichogenic SeNPs appeared around 22 , and 38 • were generally assigned to bioactive compounds from T. harzianum extract and background noise [114], although it is more probably related to unreacted Na 2 SeO 3 , which presented similar peaks [138,153]. The necessity of analytic comparison of the biosynthesized SeNPs with the raw materials is therefore essential.…”