Facile and controllable synthesis of hematite (α-Fe2O3) nanostructures using GRA-APSO and ANN: Reaction performance optimization for haemotoxicity and MRI assessment.

The strategic exploration of a synthetic approach to afford pristine theranostic nanoparticles (NPs) endowed with versatile physicochemical properties depends on their structural attributes. Therefore, optimizing their design while preserving the crystallinity will undoubtedly be a key foundational data to resolve and understand their biophysical and therapeutic properties. Herein, we report a facile synthesis of α-Fe 2 O 3 NPs under different experimental conditions via the co-precipitation technique. An optimization method- grey relational analysis coupled adaptive particle swarm optimization (GRA-APSO) and artificial neural network (ANN)-a modeling tool were employed to optimize and predict the relationship between the input parameters (pH, stirring speed, reaction temperature, and calcination temperature) and the response attributes (crystallite size, lattice strain, crystallinity index, bond length, and band gap). X-ray diffraction (XRD) pattern revealed the hematite crystal structure for NPs synthesized under initial (IE) and optimized (OE) experimental conditions. Transmission electron microscopy (TEM) confirmed the hexagonal shape of α-Fe 2 O 3 NPs with particle size averaging at 8.5 and 13.7 nm for OE and IE, respectively. Brunauer–Emmett–Teller (BET) measurements unveiled the mesoscopic structure of the as-synthesized samples with a high specific surface area (160 m2/g) for OE. The magnetic hysteresis analysis displayed the weak-ferromagnetic nature of α-Fe 2 O 3 samples. Pure α-Fe 2 O 3 NPs exhibited high T 2 relaxivity (OE-34.8 and IE-36.4 mM−1s−1). Subsequently, haemocompatibility assays demonstrated excellent compatibility of IE and OE samples toward human RBCs. Moreover, synchronous attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and circular dichroism (CD) measurements proved minimal change in the α-helical content of plasma upon association with α-Fe 2 O 3 NPs. The synergistic outcomes of the present study can promise new avenues for exploring haemocompatible α-Fe 2 O 3 NPs as a novel theranostic nanomedicine for multi-modal imaging and versatile biomedical applications. [Display omitted] • Pristine synthesis of hexagonal α-Fe 2 O 3 NPs using thermolysis-assisted co-precipitation route. • A hybrid of GRA-APSO and ANN was adopted to optimize the synthesis of α-Fe 2 O 3 NPs. • GRA inferred pH as the most influencing parameter over all NPs characteristics. • GRA-APSO depicts globally best synthesis conditions (A4, B4, C4, and D1) compared to the traditional GRA-based approach. • As-synthesized NPs showed excellent haemocompatibility, T 2 -relaxivity, and high specific surface area. [ABSTRACT FROM AUTHOR]