Diamond crystal

ATR-IR spectra were obtained using a Nicolet iS10 ATR-IR spectrometer with a diamond crystal (Thermo Fisher Scientific, United States). Samples were placed on the crystal and held steady by the specific crimping tool. The experimental set up involved acquisition of 32 scans in the range 500–4000 cm^–1, both of sample and background, at a resolution of 4 cm^–1 with the sampling depth is approximately 1.6 μm. Beside decellularized and polylysine-enriched samples, the ATR-IR spectrum of polylysine (Sigma-Aldrich, United States) was acquired as a reference.

Fourier transform
infrared (FTIR) spectroscopy was performed using a Smart iTR ATR sampling
accessory for a Nicolet iS10 spectrometer with a diamond crystal (Thermo
Scientific, Massachusetts). ¹H and ¹³C NMR spectra
were obtained on Varian 300 and 75 MHz NMR spectrometers, respectively,
in tubes with 5 mm outside diameters. CDCl₃ or DMSO-d₆ containing tetramethylsilane served as a solvent
and shift reference. Thin layer chromatography (TLC) plates were purchased
from Merck (Silica gel matrix coated with a fluorescent indicator
on aluminum plates).

To determine the percentage of functionalization of the HNTs, a Q5000 thermal gravimetric analyzer (TGA) (TA Instruments Ltd., New Castle, DE, USA) was used. In a nitrogen atmosphere, the heating rate was 10 °C/min from 30 °C to 800 °C. The top surface morphology of the membranes was evaluated using scanning electron microscopy (SEM). All of the samples were coated by gold sputtering. Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectra of the membranes (TFC and TFN membranes) and NPs were obtained using a Nicolet 6700 FT-IR instrument with a diamond crystal (Thermo Fisher, Waltham, MA, USA). OMNIC ™ software was utilized to analyze the spectra. To investigate the TFC and TFN membranes’ hydrophilicity, a VCA Optima goniometer (AST Products, Inc., Billerica, MA, USA) was used. The morphology of the nanoparticle was characterized using a TEM (Philips CM30, Algonquin, IL, USA) instrument. The zeta potential of the surface of membranes was determined using a zeta analyzer (Zetasizer PSS0012-22, Malvern Instruments, Westborough, MA, USA).

FTIR measurements were carried out in Attenuated Total Reflectance (ATR) mode using the Nicolet iS10 apparatus with an adapter equipped with a diamond crystal (Thermo Scientific). Measurements were carried out in the mid-infrared range (500–4000 cm⁻¹) using: (i) solid samples of nanoparticle powders and (ii) surface modifiers in their pure form. Thermogravimetric analysis (TGA) was carried out using a TGA/DSC3+ thermogravimeter (Mettler Toledo) at a temperature increment 10 °C/min in a temperature window of 25–750 °C and air flow rate 60 mL/min. The total content of C, H, and N elements in modified MNPs was measured using a Vario EL III analyzer with a thermal conductivity detector (Elementar, Langenselbold, Germany) by the accurate weighting of the solid sample and its burning in oxygen at 1150 °C in a dynamic system. Fe, Au, and Si content in solid MNPs was established using the ICP-MS/MS technique, analogically to the methodology presented above (see Section 3.3.2; monitored isotopes: ²⁸Si, ⁵⁶Fe, ¹⁹⁷Au at on-mass mode), but solid samples before digestion were accurately weighted. The oxygen content in the cores of surface-modified MNPs was estimated using the molar ratio of Fe/O in the synthesized bare MNPs as the rest types of the nanomaterials were formed based on such cores (with specific FeO/Fe₂O₃ ratio).