Green synthesis of curcumin-silver nanoparticle and its modified electrode assisted amperometric sensor for the determination of paracetamol.

Contamination of paracetamol, a primary analgesic was wide spread in the water system that affects the eco-system. High-dosage of paracetamol to humans cause organ damages and showed adverse effect. It is important to monitor the paracetamol concentration in environmental and human samples periodically. Conventional methods associated with chromatography is found to be high-cost, time consuming and requires high-end instrumentation, Herein, we investigated the role of curcumin during bio-synthesis of silver nanoparticles. The curcumin functionalized silver nanoparticles were further chemically modifying on the electrode surface and the resulting modified electrode was applied for electrocatalytic oxidation of paracetamol. The experimental finding proved that the modified electrode is capable of sensing paracetamol by applying oxidation potential 0.4 V. Both the synthesised material and modified electrode surface were characterized for its physic-chemical properties using spectroscopy and microscopy techniques. The HR-TEM, FESEM and AFM results showed that the distribution of nanoparticle with the size range from 25 to 70 nm and the UV-Vis and Raman spectrophotometer characterization confirms the coordination between SNP and curcumin. Under optimized condition, in 0.1 M NH4Cl (pH 7) at the scan rate of 50 mVs-1. The modified electrode enhanced the sensitivity towards the detection of paracetamol in trace level. The modified electrode is capable of sensing paracetamol in a linear range between 0.59 × 10-6 and 342.1 × 10-6 M, with LOD of 0.29 µM, and linear regression equation of y = 0.092x+502.6 with a correlation coefficient of R2 = 0.996.

Photoelectric performance evaluation of DSSCs using the dye extracted from different color petals of Leucanthemum vulgare flowers as novel sensitizers.

In this work, the natural flower extracted dyes containing luteolin were prepared using three different specimens from daisy flowers family (Leucanthemum vulgare), namely yellow daisy, purple daisy and wine daisy, according to the color of its petals. Moreover, DSSCs were fabricated using nanosized titanium dioxide (TiO2) as an anode; for the photocathodes, two different specimens were used: i) graphite electrode and ii) platinum electrode. To recognize the light absorption behavior, the existence of anchoring groups and coloring components of the extracted dyes were determined using absorption spectroscopy. The surface roughness of the photoanodes and cathodes were examined using atomic force microscope (AFM). The photovoltaic performance and efficiency of assembled DSSCs were evaluated to realize the influence of TiO2 photoanodes on interaction of the Leucanthemum vulgare extracted dye molecules with graphite or platinum photocathodes. DSSCs fabricated with platinum cathode show higher conversion efficiency (η) of 0.6%, 0.4% and 0.8% for the yellow daisy, wine daisy and purple daisy, respectively. DSSCs sensitized with daisy wine dye showed highest open-circuit voltage (Voc) of 520 mV and efficiency of 0.79% and 0.88%, for the graphite and platinum cathodes, respectively. These results showed that the DSSCs, using daisy flowers extracts as efficient photosensitizers, are suitable for the fabrication of environmentally safe, inexpensive, clean and renewable energy.

Biocompatible hydrophilic brushite coatings on AZX310 and AM50 alloys for orthopaedic implants.

Dicalcium phosphate dihydrate (DCPD) brushite coating with flake like crystal structure for the protection of AZX310 and AM50 magnesium (Mg) alloys was prepared through chemical deposition treatment. Chemical deposition treatment was employed using Ca(NO3)2·4H2O and KH2PO4 along with subsequent heat treatment. The morphological results revealed that the brushite coating with dense and uniform structures was successfully deposited on the surface of AZX310 and AM50 alloys. The X-ray diffraction (XRD) patterns and Attenuated total reflectance infrared (ATR-IR) spectrum also revealed the confirmation of DCPD layer formation. Hydrophilic nature of the DCPD coatings was confirmed by Contact angle (CA) measurements. Moreover, electrochemical immersion and in vitro studies were evaluated to measure the corrosion performance and biocompatibility performance. The deposition of DCPD coating for HTI AM50 enables a tenfold increase in the corrosion resistance compared with AZX310. Hence the ability to offer such significant improvement in corrosion resistance for HTI AM50 was coupled with more bioactive nature of the DCPD coating is a viable approach for the development of Mg-based degradable implant materials.

Selective electrooxidation of uric acid in presence of ascorbic acid at a room temperature ionic liquid/nickel hexacyanoferarrate nanoparticles composite electrode.

A novel amperometric sensor for the determination of uric acid was fabricated using room temperature ionic liquid and nickel hexacyanoferrate nanoparticle composite which was immobilized on paraffin wax impregnated graphite electrode. The nickel hexacyanoferrate nanoparticle was characterized by UV-vis, X-ray diffraction and field emission scanning electron microscopy. The electrochemical behavior of the modified electrode was investigated in detail by electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry. Various experimental parameters influencing the electrochemical behavior of the modified electrode were optimized by varying the supporting electrolyte, scan rate and pH. The apparent electron transfer rate constant (K(s)) and charge transfer coefficient (α) of the modified electrode were found to be 1.358(± 0.02)cm/s and 0.65, respectively from cyclic voltammetry. The sensor exhibited an excellent electrocatalytic activity towards the oxidation of uric acid. The interference from ascorbic acid was easily overcome by coating the modified electrode with PEDOT layer. Under optimal condition, the determination range for uric acid is from 1.0 × 10(-6)M to 2.6 × 10(-3)M and the detection limit was 3.3 × 10(-7)M (3σ). The proposed method has been used for the determination of uric acid in human urine samples.

Electrocatalytic oxidation of L-tryptophan using copper hexacyanoferrate film modified gold nanoparticle graphite-wax electrode.

A novel copper hexacyanoferrate (CuHCF) film modification on cysteamine (Cys)-gold nanoparticle (AuNp) graphite-wax (GW) composite electrode was achieved for the quantitative determination of L-Tryptophan (L-Trp) at a reduced overpotential of 400mV in comparison with the bare Cys-AuNp-GW composite electrode. This modified electrode exhibited a well resolved pair of redox peaks corresponding to the hexacyanoferrate (II/III) reactions of CuHCF film at a formal potential of 0.65 V at a scan rate of 20 mV s(-1). Electrochemical impedance spectroscopy (EIS) studies with the modified electrode showed a very low charge transfer resistance to the electron transfer kinetics of Fe(II)/Fe(III) reactions. A linear range of 8.5×10(-7) M to 1.2×10(-4) M with a detection limit of 1.85×10(-8) M was achieved for the determination of L-Trp with a sensitivity of 0.1198 µA/µM. The influence of ultrasonication on the stability of the CuHCF film modified electrode was investigated. In addition, the CuHCF film modified electrode displayed an excellent reproducibility towards the real time analysis of L-Trp in commercial milk samples.

Recovery of bipedal locomotion in bonnet macaques after spinal cord injury: footprint analysis.

Analysis of the recovery of gait after spinal cord injury has been widely demonstrated in rat and cat models using different behavioral tests and scoring systems. The present investigation was aimed to quantitatively analyze the degree of functional recovery in bipedal locomotion of bonnet macaques after inflicting spinal cord hemisection lesion. To measure the degree of locomotor recovery, we recorded four gait variables, viz., tip of opposite foot (TOF), print length (PL), toe spread (TS), and intermediary toes (IT) using a footprint analyzing technique. Monkeys were trained preoperatively to perform the monopedal hop or bipedal locomotion on runways. Footprints of trained monkeys were recorded using the nontoxic ink and white paper before and after surgery. Surgical hemisection was induced unilaterally in the right side of spinal cord at T12-L1 level of trained monkeys. In hemiplegic monkeys, initially there was a substantial decrease in TOF and PL variables of the paretic limb, which then gradually increased for longer duration and reached the near presurgical values by the 7th and 5th postoperative month, respectively. In contrast to TOF and PL, the recovery of TS and IT variables was quicker, which dramatically increased at first and then slowly recovered to levels not significantly different from the corresponding preoperative values by the 4th postoperative month. The nonparetic limb has also showed mild alterations in all footprint variables but reached the normal values much faster compared to the paretic limb. The alterations in footprint variables of hemiplegic monkeys were examined for a postoperative period of up to 1 year. The findings of this study suggest that the mechanisms underlying locomotor recovery of lesioned macaques may be correlated to the mature function of spinal pattern generator for locomotion under the impact of residual descending and afferent connections. Further, this study also indicates the functional contribution of progressive strengthening of undamaged nerve fibers through a collateral sprouts/synaptic plasticity formed in partially lesioned cord of macaques.