Dynamic light scattering instrument

About 0.2 g samples from 10 replicates of each FS were diluted separately in 10 mL of filter-sterilized, surfactant-free ultra-pure hot water (Additional file 1: Figure S9) and subsequently filtered through 20–25 μm (Grade 2 Whatman®), 2.5 μm (Grade 41 Whatman®), 0.4 μm (Whatman® 110607, Nuclepore membrane filter) and 0.2 μm (Whatman® 7182-014, Cellulose nitrate membrane filter). Final filtrates obtained from a 0.2 μm filter were pooled together with the respective FS and quantified. The spectral and morphological features of the dried NPs were analysed using Fourier Transform Raman Spectroscopy (FT-Raman) (PerkinElmer 1600 instrument, USA) and HR-SEM (Carl Zeiss Evo 18 SEM, Germany). The dispersion, stability, and size distribution of the NPs in culture medium (DMEM) were measured using the Malvern Dynamic Light Scattering instrument (Malvern, UK) in triplicates with 20 runs each.

To confirm the functionality of the magnetic microparticles, Fourier-transform infrared spectroscopy (FTIR) was applied using an FTIR spectrophotometer (Cary 660 series; Agilent Technologies, Victoria, Australia), equipped with a deuterated triglycine sulfate detector in the scanning range of 400 to 4000 cm^-1. FTIR provides an experimental and interpretive framework of the structure, interactions of natural polymer systems and physical characteristics (31 (link), 32 (link)). The surface charge and hydrodynamic size of the particles was measured using dynamic light scattering instrument (Malvern Instruments Ltd., Worcestershire, UK). The volume size distribution was calculated from the intensity of the light diffracted at each angle. Transmission electron microscopy (TEM; JEOL, Leoben, Austria) was also used to acquire images that show the surface morphology and structure of the particle solution. The effect of magnetic susceptibility and coating on the paramagnetic properties of synthesized particles was determined using vibrating sample magnetometer at room temperature (VSM, Kashan, Iran).

To determine the surface charge, zeta potential (ζ) was measured, in triplicate, using a dynamic light scattering instrument (Malvern Panalytical, Malvern, UK) as described by Bu et al. [8 (link)], with no modifications. The surface hydrophobicity of all samples was determined using the spectrofluorometric method outlined by Boyle et al. [21 (link)] and modified by Bu et al. [8 (link)].