Synthesis of surfactant-assisted nickel ferrite nanoparticles (NFNPs@surfactant) to amplify their application as an advanced electrode material for high-performance supercapacitors.

Nickel ferrite nanoparticles (NFNPs) were synthesized in an alkaline medium (pH ∼ 11) using a wet chemical co-precipitation technique. To probe the effect of surfactants on the surface morphology, particle size and size distribution of nanoparticles; two surfactants, namely, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS), were applied. The native and surfactant-assisted nickel ferrite NPs were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The addition of surfactants (CTAB/SDS) effectively controlled the secondary growth of nickel ferrite particles and reduced their size, as examined by XRD, AFM, DLS, SEM and TEM. Characterization technique results affirmed that CTAB is a more optimistic surfactant to control the clustering, dispersion and particle size (∼22 nm) of NFNPs. To identify the impact of ferrite particle size on charge storage devices, their electrochemical properties were studied by using cyclic voltammetry (CV), galvanic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte through three-electrode assembly. NiFe2O4@CTAB showed a specific capacity of 267.1 C g-1, specific capacitance of 593.6 F g-1 and energy density of 16.69 W h kg-1, which was far better than the performances of other synthesized native NFNPs and NiFe2O4@SDS having larger surface areas.

Rheological behavior of biodegradable N-succinyl chitosan-g-poly (acrylic acid) hydrogels and their applications as drug carrier and in vitro theophylline release.

Novel pH sensitive N-succinyl chitosan-g-poly (acrylic acid) hydrogels were synthesized through free radical mechanism. Rheometer was used to observe the mechanical strength of the hydrogels. In vitro degradation was conducted in SIF (pH 7.4). The effect of concentration of monomers, initiator, and crosslinking agent and pH and ionic strength of NaCl, CaCl2, and AlCl3 on swelling of the hydrogels was observed. The results showed that equilibrium swelling ratio was highly influenced by concentration of monomers, initiator, and crosslinking agent concentration, and pH and salt solutions of NaCl, CaCl2, and AlCl3. The swelling kinetics revealed that swelling followed non-Fickian anomalous transport. Furthermore, theophylline loading (DL %) and encapsulation efficiency (EE %) of the hydrogels was in the range of 15.5 ±â€¯0.15-22.8 ±â€¯0.06% and 62 ±â€¯0.15-91 ±â€¯0.26%, respectively. The release of theophylline in physiological mediums was strongly influenced by the pH. The theophylline release was in the range of 51 ±â€¯0.20-92 ±â€¯0.12% in SIF and 7.4 ±â€¯0.02-14.9 ±â€¯0.03% in SGF (pH 1.2), respectively. The release data fitted well to Korsmeyer-Peppas model. The chemical activity of the theophylline suggested that drug maintained its chemical activity after release in vitro. The results suggest that synthesized hydrogels are excellent drug carriers.