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CuO nanoparticles (NPs) stand out due to their inherent antibacterial activity, cost-effectiveness, and tunable bandgap, rendering them promising for medical, disinfection, environmental, and industrial applications. Our study aimed to synthesize CuO NPs using fish scale (FS) waste and assess the impact of calcination temperature (100 °C, 300 °C, 500 °C, and 700 °C) on their structural and antibacterial properties. XRD analysis confirmed the formation of monoclinic structured CuO, corroborated by XPS analysis indicating a Cu2+ oxidation state. Crystallographic parameters such as lattice dimensions, the volume of the unit cell, the density of the unit cell, micro-strain, and dislocation density for all four CuO NP samples were calculated using established equations. The crystallite size was estimated by employing the Scherrer equation, linear straight-line method (LSLM), Williamson–Hall (W–H) method, Halder–Wagner (H–W) method, Monshi–Scherrer (M–S) method, and size–strain plot (SSP) method. Based on the highest value of the coefficient of determination (R2), the appropriateness of the measurement techniques was determined, and the crystallite sizes were found to be 10 nm, 11 nm, 24 nm, and 35 nm, respectively. The particle size was estimated based on the FESEM and TEM images, both of which showed an increase in size with calcination temperature. FTIR detected the presence of amide bands, which originated from the FS, and the EDX analysis provided qualitative and quantitative elemental measurements. The antibacterial activity was investigated against two Gram-negative (E. coli and S. typhi) and two Gram-positive (B. megaterium and S. aureus) bacterial strains. Increasing the calcination temperature resulted in increased particle size, which led to reduced antibacterial activity. [ABSTRACT FROM AUTHOR]

Magnetic iron oxide nanoparticles have versatile applications in biomedical science that require control over shape and size distribution. Thermal decomposition is one of the best methods for controlling the size and shape of produced nanoparticles (NPs). The size distribution can be tuned (5–30 nm) by varying the reaction environment such as precursor concentration, amount of solvent used, temperature ramp, and reflux time. Iron oleate was used as a precursor solution and heated up to reflux temperature (310 °C) for 10 min within the oxygen-free environment by applying N2 gas flow. The XRD pattern confirmed the formation of NPs with a crystallite size of 17 ± 2.45 nm. Transmission electron microscope images showed moderately cubic shapes with a mean particle size of 28.67 ± 7.12 nm. Magnetic properties such as saturation magnetization, coercivity, and remanence were calculated at 23.48 emu/gm, 33 Oe, and 0.6 emu/gm, respectively, which indicated the ferromagnetic nature of the NPs. The Verwey transition was identified from the magnetization vs temperature (FC-ZFC) plot. The bondings of the oleic acid surfactant with the produced NPs were confirmed from Fourier transformation infrared spectroscopy (FTIR) data analysis. For the application of hyperthermia, the hydrophobic phase was transferred to the hydrophilic phase using cetyltrimethylammonium bromide, which was assured by the FTIR data analysis. The hyperthermia heating of NPs was measured for different concentrations of NPs (0.25, 0.5, 1, 2, and 4 mg/ml), from which specific loss power (SLP) was calculated. Among them, 0.25 mg/ml produced the most prominent SLP (2149 ± 309 w/g) that can be applied for targeted cancer treatment. [ABSTRACT FROM AUTHOR]

Three sets of starting materials Ca(NO3)2·4H2O and (NH4)2HPO4; Ca(OH)2 and H3PO4; Ca(OH)2 and (NH4)2HPO4 were chosen for the preparation of different precursors of hydroxyapatite nanoparticles (n‐HAP) by wet chemical precipitation technique denoted by HAP‐1, HAP‐2, HAP‐3. X‐ray diffraction (XRD) studies show that n‐HAP of all three types exhibited single‐phase in the as‐prepared condition. Transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) studies of as‐prepared samples showed characteristic needle‐like particles with a width of 5 nm, which were fully crystalline exhibited by the lattice fringe in HRTEM, and single‐phase demonstrated by SAED patterns. The samples were pelletized and annealed at varying temperatures in the range of 600°C–1400°C. The results indicated that HAP‐1 and HAP‐3 samples showed phase decomposition at 1400°C to form β‐tricalcium phosphate (β‐TCP) while for HAP‐2 no such decomposition occurred up to 1400°C. Data from the Vickers hardness test revealed that the hardness value up to 2.5 GPa was attained at the sintering temperature of 1200°C for HAP‐1 and HAP‐3. The hardness values are consistently higher for HAP‐2 than HAP‐1 and HAP‐3 at all sintering temperatures and attained a value of 3 GPa at 1200°C. Thus, synthesizing n‐HAP by using H3PO4; Ca(OH)2 bestows highest Vickers hardness. [ABSTRACT FROM AUTHOR]

Cobalt ferrite nanoparticle (CFN) has received attention in magnetic resonance imaging (MRI) as a promising contrast agent due to its higher saturation magnetization and magneto-crystalline anisotropy. However, the in vitro cytotoxicity of CFN has raised concern for its biomedical application as a diagnostic agent. The coating of CFN by a biocompatible polymer such as chitosan (CH) might lessen the biocompatibility concern. Therefore, in this study, we examined the applicability of chitosan-coated cobalt ferrite nanoparticle (CCN) as an MRI contrast dye and investigated its biocompatibility in vivo . Phantom MRI images revealed that the relaxivity of CCN was 121 (±8) mM -1 s -1 , indicating the potential of CCN as a T 2 -weighted contrast agent. A single intravenous (iv) administration of CCN (10 mg/kg) improved the contrast of magnetic-resonance-imaging-based angiography (MRA) and brain-MRI in male albino Wistar rats compared to the control. Furthermore, toxicity studies dependent on dose (1-20 mg/kg) and time (1-28 days) in male albino Wistar rats confirmed the in vivo biocompatibility of CCN. The physical, hematological, biochemical, and histopathological observation assured that a single iv injection of CCN up to 20 mg/kg was well adjusted with liver, kidney, heart, and brain functions. The findings of the current study consolidate CCN as a promising candidate for MRI contrast dye.