The work reports, enhancement in colloidal stability and hyperthermia efficiency of nano-spinel magnesium ferrite (MgFe2O4) by hydrophobic-to-hydrophilic surface transformation via oleic acid (OA) ...coating. The nano-spinel structured MgFe2O4 was prepared by the auto-combustion assisted sol-gel route and consequently, its surface was coated by OA. The uncoated and coated MgFe2O4 were portrayed by various physicochemical characterizations. The XRD analysis assured the unchanged single phasic cubic spinel structure and nanocrystalline nature of both the samples. FT-IR spectral analysis indicated the spinel belonging two vibrational stretching modes and OA attachment over the MgFe2O4 core. FE-SEM images revealed the nano-metric spherical type grain-morphology and visualization of OA coating. The drastic diminishment in contact angle values signifies hydrophobic to hydrophilic surface transition. M − H plots revealed the superparamagnetic appearance of uncoated and coated samples. Physisorption analysis showed the elevated surface area and pore size values. Zeta potential and DLS study displayed the enhancement in fluidic dispersion and hydro-dynamic size. The nano-particle concentration (2–10 mg/mL) dependent hyperthermia analysis was carried out for both the samples. Cell viability studies confirmed the improvement in the bio-friendly nature of MgFe2O4 via OA coating. All the outcomes show the superiority of the surface transformed MgFe2O4 nanoparticles in nano-magnetic hyperthermia treatments.
•Hydrophobic to hydrophilic surface transformation of nanoscale MgFe2O4 by oleic acid (OA) coating was done successfully.•Effect of OA coating on the structural, morphological, surface, magnetic and colloidal stability properties were studied.•Systematic investigations of magnetic hyperthermia properties and cytotoxicity analysis were carried out.•Enhancement in the colloidal stability and particle size distribution by OA coating was observed.•OA coated MgFe2O4 shows potentiality in hyperthermia therapies for cancer treatment and other biomedical applications.
The present study compiles with the physicochemical, magnetic, and photocatalytic evaluation of the mixed spinel Ni–Zn nanoferrites prepared by the auto-combustion sol–gel route. All the samples were ...characterized by XRD for the recognition of phase-pure cubic spinel structure. Spectral studies that were carried out by FT-IR clearly show two absorptions band revealing the characteristics of ferrite skeleton. The morphology of the prepared nanoparticles was visualized by SEM and TEM microscopy technique. BET analysis showed the enhancement in surface parameters. Hydrodynamic diameter and dispersion studies were evaluated by DLS and Zeta potential measurements. The DC resistivity measured by two-probe technique shows the semiconductor behavior for all the samples. M–H hysteresis loop of all the samples exhibited the superparamagnetic behavior. The energy bandgap values obtained by the UV–Vis spectroscopy technique show the increasing trend from 1.82 to 2.07 eV with increase in Ni
2+
content. The photocatalytic activity of Rhodamine B was evaluated under sunlight irradiation. With increasing Ni
2+
concentration, the degradation efficiency increased to 98%. Further, the present nanocatalyst shows active reusability and can be easily separable due to its magnetic nature. The obtained results show the enhanced photocatalytic of the Ni–Zn nanoferrites under the visible light in contrast with the available literature reports.
In the present work, Zn-ferrite nanoparticles have been synthesized by chemical co-precipitation method. Prepared samples were characterized by XRD and FTIR to study its structural and chemical ...properties. The formation of single phase with Fd-3m space group of Zn- ferrite was revealed by XRD and also studied the effect of synthesis techniques on structural parameters. Crystallite size of ZnFe2O4 was found to be 26.11 nm. The FTIR spectra showed two expected bands in the range 550-560 cm1 (i.e. U1) and 400 -410 cm1 (i.e. u2) which confirms the formation of ferrite phase.
Oleic acid-coated cobalt ferrite nanoparticles were synthesized using the chemical co-precipitation route and characterized by standard techniques for structure, morphology, and magnetic properties ...analysis. The Rietveld refined X-ray diffraction (XRD) pattern of CoFe2O4 nanoparticles indicated the formation of a cubic-spinel single-phase structure with the Fd3̅m space group. The average crystallite size (∼12 nm) confirmed the nanocrystalline appearance of the prepared CoFe2O4 nanoparticles. Transmission electron microscopy (TEM) images revealed the spherical nature of both (CoFe2O4) and (OA-CoFe2O4) samples. The absorption bands in the Fourier transform infrared (FT-IR) spectrum at ∼3418, 3026, 1628, 1404, 1068, 845, 544, and 363 cm–1 affirmed the spinel ferrite formation and OA attachment. The M–H curve recorded at room temperature showed the superparamagnetic nature of the CoFe2O4 nanoparticles with moderate saturation magnetization (∼78 emu/gm). The blocking temperature of the prepared CoFe2O4 nanoparticles obtained from the field-cooled and zero-field-cooled (FC–ZFC) curve was estimated to be 144 K. Further, the characterized surface-modified CoFe2O4 was then added in ethylene glycol/water with various concentrations and characterized by the induction heating technique for the evaluation of their self-heating characteristics. A series of temperature versus time measurements were made by varying the ethylene glycol/water proportion for better understanding of the self-heating characteristics of the prepared CoFe2O4 nanoparticles. All of the findings display the applicability of the surface-modified CoFe2O4 nanoparticles in magnetic fluid hyperthermia toward noninvasive cancer treatment and other bio-applications.
Rare earth Neodymium (Nd3+) doped nanocrystalline Ni-Co mixed spinel ferrites which are chemically represented as Ni0.5Co0.5NdxFe2-xO4 (x = 0.025 to 0.125, in the step of 0.025) were synthesized by ...sol-gel auto-combustion method. The structural, morphological, infrared and magnetic properties were studied in detail in the light of Nd3+ doping using standard techniques. X-ray analysis reveals the formation of single phase cubic spinel structure for all the prepared samples without any impurity phase. The crystallite size calculated from Scherrer's formula was observed to be decreasing with increasing Nd3+ content. The lattice parameter calculated using XRD data was found to be decreasing upto x = 0.100 and then increases for x = 0.125. X-ray density was observed to be increasing from 5.327 to 5.630 gm/cm3. Surface morphology was studied through scanning electron microscopy technique. Grain size calculated from SEM analysis was found to be in the range of 30–59 nm. From transmission electron microscopy study, the average particle size was observed to be in the range of 35–45 nm. FTIR results exhibit the characteristics cubic spinel ferrite nature of the samples with two prominent absorption bands near 400 cm−1 and 600 cm−1. FTIR also confirms the incorporation of Nd3+in the crystal structure. The magnetic behavior shows strong influence of substitution of Nd3+ions. The saturation magnetization, coercivity and remenance magnetization all decrease with substitution of Nd3+ ions up to x = 0.100. For further increase in Nd3+ concentration (x = 0.125), the saturation magnetization found to be increased.
•Nd3+ incorporation maintained single phase cubic structure of Ni-Co ferrite.•Lattice strain with Nd3+ was increased.•FESEM micrographs exhibited agglomeration of grains with size varying from 30 to 59 nm.•Saturation magnetization upto x = 0.1 was decreased while for x = 0.125 it increases.•Observed Canting effect reveal the non-collinear structure.
In the present work, Co1-xZnxFe2O4 (x = 0.0, 0.3, 0.5, 0.7 and 1.0) nanoparticles were prepared by chemical co-precipitation method. Prepared Co1-xZnxFe2O4 ferrite powder was sintered at 900 °C for ...4 h after TG-DTA thermal studies. XRD analysis revealed the single-phase cubic structure of Co–Zn ferrite nanoparticles and also studied the variation in structural parameter with increasing Zn concentration. The formation of the ferrite phase was confirmed by studying FTIR spectra. The SEM images shows the agglomeration of spherical grains due to the difference in the magnetic nature of the sample. Peaks of respective elements (Co, Zn, Fe, and O) in EDX spectra show the formation of cobalt zinc ferrite. Variation of energy band gap with increasing zinc concentration in cobalt ferrite studied by UV–Vis. Spectroscopy. The M − H loops revealed that the values of magnetic parameters such as MS, Mr, Hc, nB, and Mr/Ms ratio decrease with increasing Zn2+ content in cobalt ferrite nanoparticles.
•Zn2+ substituted cobalt ferrite nanoparticles have been successfully prepared by wet chemical route.•XRD studies confirmed the formation of cubic spinel structure.•It's infrared, morphological, optical and magnetic properties were investigated.•Magnetic properties were influenced significantly by nonmagnetic Zn2+ ion substitution in cobalt ferrite.•Zn2+ ion substituted cobalt ferrite nanoparticles are desirable in biomedical applications.
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•Synthesis of CoFe2O4 nanoparticles by sol-gel autocombustion using different fuels.•Effects of fuels on different properties of CoFe2O4 nanoparticles were compared.•By using urea as ...a fuel smaller particle size can be achieved.•Superparamagnetic nature for all the samples was noticed irrespective of fuels.•Improved magnetic properties can be achieved using ethylene glycol as a fuel.
The spinel structured cobalt ferrite (CoFe2O4) nanoparticles were successfully synthesized by sol-gel auto combustion method using three different fuels (Ethylene glycol, Glycine and Urea) approach. Pure phase formation of cobalt ferrite with cubic spinel structure was observed for all the samples in X-ray diffraction patterns. The average crystallite size, lattice parameter and other structural parameters were calculated from XRD data. The lower value of average particle size of 15 nm was noticed with urea as fuel. The sponge-like spherical shaped morphology was observed irrespective of the fuels. The average grain size was found to be in the range of 65–86 nm. The enhanced saturation magnetization, coercivity and other magnetic parameters obtained by M-H plots confirmed the superparamagnetic behaviour of the samples. It is observed from experimental results that using urea as a fuel one can obtain smaller particle size while the improved magnetic properties were observed for ethylene glycol as a fuel.
Foodborne pathogens are major public health concerns worldwide. Paper-based microfluidic devices are versatile, user friendly and low cost. We report a novel paper-based single input channel ...microfluidic device that can detect more than one whole-cell foodborne bacteria at the same time, and comes with quantitative reading via image analysis. This microfluidic paper-based multiplexed aptasensor simultaneously detects E. coli O157:H7 and S. Typhimurium. Custom designed particles provide colorimetric signal enhancement and false results prevention. Several aptamers were screened and the highest-affinity aptamers were optimized and employed for detection of these bacteria in solution, both in a buffer as well as pear juice. Image analysis was used to read and quantify the colorimetric signal and measure bacteria concentration, thus rendering this paper based microfluidic device quantitative. The colorimetric results show linearity over a wide concentration range (102CFU/mL to 108CFU/mL) and a limit of detection (LOD) of 103CFU/mL and 102CFU/mL for E. coli O157:H7 and S. Typhimurium, respectively. An insignificant change in colorimetric response for non-target bacteria indicates the aptasesnors are specific. The reported multiplexed colorimetric paper-based microfluidic devices is likely to perform well for on-site rapid screening of pathogenic bacteria in water and food products.
Structural morphology and magnetic properties of the Co1−xZnxFe2O4 (0.0≤x≥1.0) spinel ferrite system synthesized by the sol–gel auto-combustion technique using nitrates of respective metal ions have ...been studied. The ratio of metal nitrates to citric acid was taken at 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 600°C for 12h after TG/DTA thermal studies. Compositional stoichiometry was confirmed by energy dispersive analysis of the X-ray (EDAX) technique. Single phase cubic spinel structure of Co–Zn nanoparticles was confirmed by XRD data. The average crystallite size (t), lattice constant (a) and other structural parameters of zinc substituted cobalt ferrite nanoparticles were calculated from XRD followed by SEM and FTIR. It is observed that the sol–gel auto-combustion technique has many advantages for the synthesis of technologically applicable Co–Zn ferrite nanoparticles. The present investigation clearly shows the effect of the synthesis method and possible relation between magnetic properties and microstructure of the prepared samples. Increase in nonmagnetic Zn2+ content in cobalt ferrite nanoparticles is followed by decrease in nB, Ms and other magnetic parameters. Squareness ratio for the Co-ferrite was 1.096 at room temperature.
•Co–Zn nanoparticles are prepared by sol–gel auto-combustion method.•Structural properties were characterized by XRD, SEM, and FTIR.•Compositional stoichiometry was confirmed by EDAX analysis.•Magnetic parameters were measured by the pulse field hysteresis loop technique.
Here, we report the influence of nonmagnetic Al3+ and magnetic Cr3+ co-substitution on the structural, morphological, magnetic and Mössbauer properties of nickel ferrite nanoparticles synthesized via ...sol-gel auto combustion route. Citric acid was used as a fuel and metal nitrate to fuel ratio was chosen to be 1:3. The resultant powder was sintered at 550 °C for 4 h and used for further characterizations. Single phase formation and nanocrystalline nature was confirmed through X-ray diffraction analysis. The crystallite size of all the samples calculated through Debye-Scherrer’s formula found to be in the range of 18–55 nm. The lattice constant calculated from XRD data show decreasing trend. Scanning electron microscopy technique was used to study the surface morphology of typical samples (x = 0.0 and 0.4). The average grain size determined through SEM images found to be 70 nm–35 nm respectively for x = 0.0 and 0.4 samples. The magnetic properties were investigated through magnetization and Mössbauer spectroscopy technique. The saturation magnetization measured from M-H hysteresis plot show decreasing trend with increase in Al–Cr content x. Using Mössbauer spectra the relative area of a sextet (T), Isomer shift (δ), Hyperfine Field (Hf), Quadrupole Splitting (Δ) and Line width (Γ) were calculated. Overall, the co-substitution of Al–Cr has significantly influenced the structural, morphological and magnetic properties of nickel ferrite nanoparticles.
•Al3+ and Cr3+ co-substituted nickel ferrite nanoparticles have been successfully prepared by wet chemical route.•XRD studies confirmed the formation of cubic spinel structure.•It’s morphological, magnetic and Mossbauer properties were investigated.•Magnetic properties were influenced significantly by nonmagnetic Al3+ and magnetic Cr3+ ion substitution in nickel ferrite.•Al3+ and Cr3+ co-substituted nickel ferrite nanoparticles are desirable in high frequency electronic devices.
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