Abstract
Bioactive glasses (BGs) are attractive materials for bone replacement due to their tailorable chemical composition that is able to promote bone healing and repair. Accordingly, many attempts have been introduced to further improve BGs’ biological behavior and to protect them from bacterial infection, which is nowadays the primary reason for implant failure. Polyphenols from natural products have been proposed as a novel source of antibacterial agents, whereas silver is a well-known antibacterial agent largely employed due to its broad-ranged activity. Based on these premises, the surface of a bioactive glass (CEL2) was functionalized with polyphenols extracted from the Egyptian algae Padina pavonica and enriched with silver nanoparticles (AgNPs) using an in situ reduction technique only using algae extract. We analyzed the composite’s morphological and physical-chemical characteristics using FE-SEM, EDS, XPS and Folin–Ciocalteau; all analyses confirmed that both algae polyphenols and AgNPs were successfully loaded together onto the CEL2 surface. Antibacterial analysis revealed that the presence of polyphenols and AgNPs significantly reduced the metabolic activity (>50%) of Staphylococcus aureus biofilm in comparison with bare CEL2 controls. Finally, we verified the composite’s cytocompatibility with human osteoblasts progenitors that were selected as representative cells for bone healing advancement.
Highlights
Due to the continuous increase in chronic/non-chronic etiologies resulting in different kinds of bone defects, scientists have aimed to find new strategies to promote bone tissue reconstruction via self-regenerative stimulation [1,2,3].Coatings 2019, 9, 394; doi:10.3390/coatings9060394 www.mdpi.com/journal/coatingsBioactive glasses (BGs) are biocompatible materials, currently applied for rapid induction of bone tissue regeneration due to their tailorable chemical composition that is able to promote bone healing and repair
Prior to undergoing CEL2 surface functionalization, the total polyphenol content in P. pavonica extract was evaluated by means of the Folin–Ciocalteau test to determine whether the selected source was sufficient to provide an adequate bulk of polyphenols
Results confirmed that the selected P. pavonica algae was rich in polyphenols as the total amount resulted in 75.6 mg gallic acid equivalent (GAE)/g dry weight (DW)
Summary
Bioactive glasses (BGs) are biocompatible materials, currently applied for rapid induction of bone tissue regeneration due to their tailorable chemical composition that is able to promote bone healing and repair This process is promoted by BGs osteoconduction and osteoinduction properties: once a BG is introduced into the defect, an immediate and continuous dissolution of critical concentrations of soluble P, Ca, Si, and Na ions stimulates the self-renewal healing of the healthy bone surrounding the defect [4,5,6]. Once the BG comes into contact with the physiological environment, it starts to release Na+ and Ca2+ ions and to exchange H+ , forming a hydrated silica gel on the surface This gel turns into an amorphous CaO-P2 O5 -SiO2 layer with a continuous consumption of Ca2+ and PO4 3− , and subsequently crystallizes into a hydroxycarbonate apatite (HCA) layer through constant incorporation with Ca2+ , PO4 3− , OH− , and CO3 2− [7,8]. The growing HCA layer provides an ideal environment for osteoblasts colonization, proliferation, and differentiation [9,10]
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