Hydroxyapatite hap

The following medical-grade ingredients were used to generate the collagen-based composite compositions to be used for skin lesion healing: collagen gel with an initial concentration of 1.77% (w/w) and with a pH of 1.8 was prepared from calfskin in conformity with the actual method established and used at the Collagen Research Department of the Division of Leather and Footwear Research Institute [69 ], hydroxyapatite (HAp) with purity p.a., ≥90% from (Sigma-Aldrich Chemie GmbH, Taufkirchen Germany), essential oils (EOs) (cinnamon EO obtained from Cinnamomum verum bark, and basil EO obtained from Ocimum basilicum leaf). Distilled water served as the solvent for preparing the experimental samples. Because the essential oils are volatile, we mixed the same amount of HAp with different quantities of essential oils: 1% hydroxyapatite and 1% essential oil (except reference sample, R, which consists of 1% collagen and 1% HAp) were added to the collagen gel (with an initial concentration of 1.77%). The composite gels were adjusted to 7.4 pH with sodium hydroxide 1 M and 15 mL of water (under stirring). The sample with 1% basil essential oil was marked as A1B, that with 1% cinnamon essential oil was marked A1C, and the one with both essential oils was named A1BC as is presented in Table 1. These composite gels were cross-linked with glutaraldehyde (0.05%) and finally put into glass Petri dishes with a diameter of 5 cm and a height of 1 cm. After that, they were placed in a lyophilizer, previously cooled to −40 °C, for 90 min.
The lyophilization process lasted 48 h [69 ], obtaining samples corresponding to the prepared composite gels (Figure 2), which were subsequently characterized.

Gelatin (Gel, type B from porcine skin), hydroxyapatite (HAp, with 99 % purity), polyetherimide (PEI), oligomeric proantho cyanidins (OPC, with 95 % purity), 2,2-diphenyl-1-(2,4,6-trinitrophenyl)-Hydrazine group (DPPH, with 97 % purity) are purchased from Sigma-Aldrich Trading Co., Ltd. (Shanghai, China). For cell culture, Dulbecco's modified eagle medium (DMEM), fetal bovine serum (FBS), pancreatic enzyme and other relevant reagent are obtained from Hyclone Trading Co., Ltd. (Shanghai, China). Calcein-AM and propidium iodide (PI) are utilized to identify live/dead cells.
All the above-mentioned solvents and reagents are of analytical grade and can be used without further purification.

A polyester carrier yarn (PES, ELASTEX Krnov,
Czech Republic) was used for the preparation of the composite yarns
for technical application purposes, and Chirlac Rapid braided surgical
yarn (Chirana T.Injecta, Czech Republic) was used for the preparation
of composite yarns for medical applications. Polyvinyl butyral (PVB,
Mowital B 60 H, Kuraray America, USA), polyamide 6 (PA 6, Ultramid
B27, BASF, Germany), and polycaprolactone (PCL, Mn 80,000, Sigma-Aldrich,
Germany) were used to form the nanofiber coating. The solvents used
to prepare the solutions comprised ethanol, acetic acid, formic acid,
sulfuric acid, and acetone (all Penta Chemicals, Czech Republic).
The incorporated materials consisted of activated carbon, Sorbetin
(Eco Expert, Czech Republic), and hydroxyapatite (HAP) (Sigma-Aldrich,
Germany).

Expanded polystyrene waste and monofilament fishing line were recycled and utilized without additional purification. Polytetrafluoroethylene microparticles (PTFE-µPs) (particle size = 3 µm, M_w = 678.10 gmol⁻¹), silicon dioxide nanoparticles (SiO₂-NPs) (particle size = 60–70 nm, M_w = 100 gmol⁻¹), and silver nanoparticles (Ag-NPs) (99.99%, 20 nm, metal basis) were purchased from U.S. Research Nanomaterials Inc. (Houston, TX, USA). Hydroxyapatite (HAp) (<200 nm, M_w = 502.31 gmol⁻¹) was purchased from Sigma-Aldrich (St. Louis, MO, USA). The chemical reagents N, N-Dimethylformamide (DMF) (C₃H₇NO, 99.8%), acetone (C₃H₆O), and acetic acid (CH₃COOH) were purchased from Thermo Fisher Scientific (Waltham, MA, USA). Formic acid (CH₂O₂, 99%) was purchased from Manofohm Chemicals (Florence, CO, USA). Chitosan powder was procured from Chemsavers (90+% deacetylated) (Bluefield, VA, USA). Polyethylene glycol (M_w = 7000–9000 gmol⁻¹) was purchased from HiMedia Laboratories (Kennett Square, PA, USA). Glycerol phosphate disodium salt (isomeric mixture of 50% β-isomer and 50% rac-α-isomer) was obtained from GTI Laboratory Supplies (Edna, TX, USA). Bovine serum albumin (98% purity) was purchased from Protein Mods, LLC (Waunakee, WI, USA). Aloe vera leaf juice (99.5% purity) was purchased from Nature’s Way Brands, LLC (Green Bay, WI, USA). E. coli and S. aureus were obtained from Sigma-Aldrich (St. Louis, MO, USA). Fibroblast cell lines (3T3 and L-929 cells) were obtained from American Type Culture Collection (ATCC) (Manassas, VA, USA) and cell culture medium and reagents were from ThermoFisher Scientific (thermofisher.com, accessed on 30 March 2021) and ScienCell Research Laboratories (Carlsbad, CA, USA). The chemical reagents and cell medium were employed in their original form without any modifications or additional purification steps.