Fabrication of α‑Fe2O3 Nanostructures: synthesis, characterization, and their promising application in the treatment of Carcinoma A549 Lung Cancer Cells

In the present work, iron nanoparticles were synthesized in the α-Fe2O3 phase with the reduction of potassium hexachloroferrate(III) by using l-ascorbic acid as a reducing agent in the presence of an amphiphilic non-ionic polyethylene glycol surfactant in an aqueous solution. The synthesized α-Fe2O3 NPs were characterized by powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet–visible spectrophotometry. The powder X-ray diffraction analysis result confirmed the formation of α-Fe2O3 NPs, and the average crystallite size was found to be 45 nm. The other morphological studies suggested that α-Fe2O3 NPs were predominantly spherical in shape with a diameter ranges from 40 to 60 nm. The dynamic light scattering analysis revealed the zeta potential of α-Fe2O3 NPs as −28 ± 18 mV at maximum stability. The ultraviolet–visible spectrophotometry analysis shows an absorption peak at 394 nm, which is attributed to their surface plasmon vibration. The cytotoxicity test of synthesized α-Fe2O3 NPs was investigated against human carcinoma A549 lung cancer cells, and the biological adaptability exhibited by α-Fe2O3 NPs has opened a pathway to biomedical applications in the drug delivery system. Our investigation confirmed that l-ascorbic acid-coated α-Fe2O3 NPs with calculated IC50 ≤ 30 μg/mL are the best suited as an anticancer agent, showing the promising application in the treatment of carcinoma A549 lung cancer cells

A novel catalytic kinetic method for the determination of mercury(ii) in water samples

Mercury(II) ions act as catalyst in the substitution of cyanide ion in hexacyanoruthenate(II) by pyrazine (Pz) in an acidic medium. This property of Hg(II) has been utilized for its determination in aqueous solutions. The progress of reaction was followed spectrophotometrically by measuring the increase in absorbance of the yellow colour product, [Ru(CN)5Pz]3− at 370 nm (λmax, ε = 4.2 × 103 M−1 s−1) under the optimized reaction conditions; 5.0 × 10−5 M [Ru(CN)64−], 7.5 × 10−4 M [Pz], pH 4.00 ± 0.02, ionic strength (I) = 0.05 M (KCl) and temp. 45.0 ± 0.1 °C. The proposed method is based on the fixed time procedure under optimum reaction conditions. The linear regression (calibration) equations between the absorbance at fixed times (t = 15, 20 and 25 min) and [Hg(II)] were established in the range of 1.0 to 30.0 × 10−6 M. The detection limit was found to be 1.5 × 10−7 M of Hg(II). The effect of various foreign ions on the proposed method was also studied and discussed. The method was applied for the determination of Hg(II) in different wastewater samples. The present method is simple, rapid and sensitive for the determination of Hg(II) in trace amount in the environmental samples

Kinetics and mechanism of pentacyanohydroxoferrate(III) formation from the reaction of [FeL(OH)]^2-n complexes with cyanide ions [L^n- <i>=trans-</i>1 ,2-diaminocyclohexanetetraacetic acid (CYDTA) and nitrilotriacetic acid (NTA)]

2307-2314The kinetics and mechanism of exchange of CYDTA4- in [FeCYDTA (OH)]2- and NTA3- in [FeNTA(OH)]l- with cyanide ions (CYDTA 4- = trans-1,2-diaminocyclohexanetetraacetic acid and NTA = nitrilotriacetic acid) have been investigated spectrophotometrically at 395 nm (λmax of [Fe(CN)5OH]3-) under the conditions, temp. = 45 ± 0.1 °C, pH = 11±0.02 and I= 0.25 M(NaClO4) for CYDTA and temp. 25±0.1oC, pH =9.0 ± 0.02 and I=0.4 M (NaClO4) for NTA. Both the reactions exhibit three observable stages leading to the formation of [Fe(CN)5OH]3-, [Fe(CN)6]3- and [Fe(CN)6]4- respectively. The [FeCYDT(OH)]2--CN- as well as [FeNTA(OH)]1--CN- systems show variable order dependences in [CN-] in their first stage, ranging from one to two and zero to one at low and high cyanide concentrations. The second stage of reaction is common for both the systems and follow a first order dependence each in [Fe(CN)5OH3-] and [CN-].The third stage of reaction follows a overall second order kinetics, first order each in [Fe(CN)5OH3-] and [Ln-] (Ln- = CYDTA 4- and NTA3-). The thermodynamically unfavourable reverse reaction of [Fe(CN)5OH3-] with [CYDTA]4- and [NTA3-] have also been studied under forcing conditions by taking large excess of [CYDTA]4- and [NTA]3-.These reactions exhibit first order dependence each in [Fe(CN)5OH3-] &nbsp;and [CYDTA4-] or [NTA3-] and an inverse first order dependence in [CN-] which makes it possible to identify the fourth step as rate determining one. The dependence of forward rate on ionic strength also confirms that the fourth step is rate determining in the porposed reaction mechanism for the first stage of reaction. A five step mechanistic scheme is proposed for both the systems in their first stage of reaction involving the presence of four cyanide ions around the central iron atom in the rate determining step. The activation parameters for both forward and backward reactions of the first stage of reaction are evaluated and they support the proposed mechanism