Synthesis and characterization of green agents coated Pd/Fe bimetallic nanoparticles

Utility of Biogenic Iron and Its Bimetallic Nanocomposites for Biomedical Applications: A Review

Nanotechnology mainly deals with the production and application of compounds with dimensions in nanoscale. Given their dimensions, these materials have considerable surface/volume ratios, and hence, specific characteristics. Nowadays, environmentally friendly procedures are being proposed for fabrication of Fe nanoparticles because a large amount of poisonous chemicals and unfavorable conditions are needed to prepare them. This work includes an inclusive overview on the economical and green procedures for the preparation of such nanoparticles (flower, fruits, tea, carbohydrates, and leaves). Pure and bimetallic iron nanoparticles, for instance, offer a high bandwidth and excitation binding energy and are applicable in different areas ranging from antibacterial, anticancer, and bioimaging agents to drug delivery systems. Preparation of nano-sized particles, such as those of Fe, requires the application of high quantities of toxic materials and harsh conditions, and naturally, there is a tendency to develop more facile and even green pathways (Sultana, Journal of Materials Science & Technology, 2013, 29, 795–800; Bushra et al., Journal of hazardous materials, 2014, 264, 481–489; Khan et al., Ind. Eng. Chem. Res., 2015, 54, 76–82). This article tends to provide an overview on the reports describing green and biological methods for the synthesis of Fe nanoparticles. The present review mainly highlights selenium nanoparticles in the biomedical domain. Specifically, this review will present detailed information on drug delivery, bioimaging, antibacterial, and anticancer activity. It will also focus on procedures for their green synthesis methods and properties that make them potential candidates for various biomedical applications. Finally, we provide a detailed future outlook.

Physicochemical Properties and Atomic-Scale Interactions in Polyaniline (Emeraldine Base)/Starch Bio-Based Composites: Experimental and Computational Investigations

The processability of conductive polymers still represents a challenge. The use of potato starch as a steric stabilizer for the preparation of stable dispersions of polyaniline (emeraldine base, EB) is described in this paper. Biocomposites are obtained by oxidative polymerization of aniline in aqueous solutions containing different ratios of aniline and starch (% w/w). PANI-EB/Starch biocomposites are subjected to structural analysis (UV-Visible, RAMAN, ATR, XRD), thermal analysis (TGA, DSC), morphological analysis (SEM, Laser Granulometry), and electrochemical analysis using cyclic voltammetry. The samples were also tested for their solubility using various organic solvents. The results showed that, with respect to starch particles, PANI/starch biocomposites exhibit an overall decrease in particles size, which improves both their aqueous dispersion and solubility in organic solvents. Although X-ray diffraction and DSC analyses indicated a loss of crystallinity in biocomposites, the cyclic voltammetry tests revealed that all PANI-EB/Starch biocomposites possess improved redox exchange properties. Finally, the weak interactions at the atomic-level interactions between amylopectin–aniline and amylopectin–PANI were disclosed by the computational studies using DFT, COSMO-RS, and AIM methods.

Cd(II) and Pb(II) Adsorption Using a Composite Obtained from Moringa oleifera Lam. Cellulose Nanofibrils Impregnated with Iron Nanoparticles

This work informs on the green synthesis of a novel adsorbent and its adsorption capacity. The adsorbent was synthesized by the combination of iron nanoparticles and cellulose nanofibers (FeNPs/NFCs). Cellulose nanofibers (NFCs) were obtained from Moringa (Moringa oleifera Lam.) by a pulping Kraft process, acid hydrolysis, and ultrasonic methods. The adsorption method has advantages such as high heavy metal removal in water treatment. Therefore, cadmium (Cd) and lead (Pb) adsorption with FeNP/NFC from aqueous solutions in batch systems was investigated. The kinetic, isotherm, and thermodynamic parameters, as well as the adsorption capacities of FeNP/NFC in each system at different temperatures, were evaluated. The adsorption kinetic data were fitted to mathematical models, so the pseudo-second-order kinetic model described both Cd and Pb. The kinetic rate constant (K2), was higher for Cd than for Pb, indicating that the metal adsorption was very fast. The adsorption isotherm data were best described by the Langmuir–Freundlich model for Pb multilayer adsorption. The Langmuir model described Cd monolayer sorption. However, experimental maximum adsorption capacities (qe exp) for Cd (>12 mg/g) were lower than those for Pb (>80 mg/g). In conclusion, iron nanoparticles on the FeNP/NFC composite improved Cd and Pb selectivity during adsorption processes, indicating the process’ spontaneous and exothermic nature.

Enhanced removal of 1,2,4-trichlorobenzene by modified biochar supported nanoscale zero-valent iron and palladium

Biochar pyrolysed at 300 °C, 500 °C, 700 °C was modified by hydrochloric acid (HCl), hydrofluoric acid (HF), sodium hydroxide (NaOH), hydrogen peroxide (H₂O₂), nitric acid (HNO₃) and potassium permanganate (KMnO₄), and subsequently evaluated for removal efficiency of 1,2,4-trichlorobenzene (1,2,4-TCB) by biochar supported nanoscale zero-valent iron (nZVI) and palladium (Pd) composites. Under the initial 1,2,4-TCB concentration of 10 mg L^-1 and the solid-liquid ratio of 0.16 g L^-1, the synthesized composites of nZVI-Pd with BC700 modified by HF (FBC700-nZVI-Pd) and nZVI-Pd with BC300 modified by NaOH (SBC300-nZVI-Pd) demonstrated significantly enhanced removal efficiencies for 1,2,4-TCB achieving 98.8% and 94.7% after 48 h, respectively. The physicochemical properties of biochar including specific surface area, aromaticity and hydrophobicity after the modification by HF and NaOH were improved. Increased the supporting sites for Fe/Pd nanoparticles and the contact between composites and 1,2,4-TCB were mainly responsible for enhanced removal efficiency for 1,2,4-TCB. Both the adsorption by biochar and reduction by Fe/Pd nanoparticles effectively contributed to the removal of 1,2,4-TCB. It is estimated that the proportion of reduction was about twice that of adsorption in the first 12 h, which produced 1,2-DCB, benzene and other degradation products. Therefore, biochar treated with HF and NaOH and supported Fe/Pd nanoparticles could be effective functional materials for remediation of groundwater contaminated by 1,2,4-TCB.

Modification of zero valent iron nanoparticles by sodium alginate and bentonite: Enhanced transport, effective hexavalent chromium removal and reduced bacterial toxicity

The rapid aggregation/sedimentation and decreased transport of nanoscale zero-valent iron (nZVI) particles limit their application in groundwater remediation. To decrease the aggregation/sedimentation and increase the transport of nZVI, sodium alginate (a natural polysaccharide) and bentonite (one type of ubiquitous clay) were employed to modify nZVI. Different techniques were utilized to characterize the modified nZVI. We found that modification with either sodium alginate or bentonite could disperse nZVI and shifted their zeta potentials from positive to negative. Comparing with the bare nZVI, the sedimentation rates of modified nZVI either by sodium alginate or bentonite are greatly decreased and their transport are significantly increased. The transport of modified nZVI can be greatly increased by increasing flow rate. Furthermore, Cr(VI) can be efficiently removed by the modified nZVI (both sodium alginate and bentonite modified nZVI). Comparing with bare nZVI, the two types of modified nZVI contain lower toxicities to Escherichia coli. The results of this study indicate that both sodium alginate and bentonite can be employed as potential stabilizers to disperse nZVI and improve their application feasibility for in situ groundwater remediation.

Enhanced solubilization and reductive degradation of 2,2',4,4'- tretrabromodiphenyl ether by PAC-Pd/Fe nanoparticles in the presence of surfactant

2,2',4,4'-Tretrabromodiphenyl ether (BDE47) is known as a typical polybrominated diphenyl ethers (PBDEs) due to its high environmental abundance, ecological toxicity, and bioaccumulation. In this study, the influences of three typical surfactants (CTAB, SDS, and TX-100) on BDE47 solubilization and degradation by the polyanionic cellulose-stabilized Pd/Fe (PAC-Pd/Fe) nanoparticles were investigated. The results showed that BDE47 solubilities increased linearly when surfactant concentrations were above their critical micelle concentrations (CMCs), and the solubilization capacities of surfactants for BDE47 followed the order of TX-100 > CTAB > SDS. The appropriate dosages of surfactants were favorable for BDE47 degradation due to enhancing solubilization and accelerating mass transfer, while excessive surfactants inhibited BDE47 degradation due to excessive and thicker micelles formed, but still higher than no surfactant. The influences of various factors (PAC-Pd/Fe nanoparticle dosage, solution pH, and temperature) on BDE47 degradation in TX-100 solution were also tested. The results showed that BDE47 degradation followed the pseudo first-order kinetics model. The degradation rates of BDE47 increased as PAC-Pd/Fe nanoparticle dosage and temperature increased. Weak acidic condition (pH 5.5) was favorable for BDE47 degradation with 96.8% BDE47 was removed within 7.5 min, while alkaline condition (9.0) was not conducive to the degradation of BDE47. The degradation of BDE47 by PAC-Pd/Fe nanoparticles was a catalytic reductive debromination process via active H-species attack, wherein the sequential debromination was the dominant reaction. This study suggests that in the presence of moderate surfactant, PAC-Pd/Fe nanoparticles may be potentially employed to eliminate BDE47 in contaminated water.

Antimicrobial gum bio-based nanocomposites and their industrial and biomedical applications

Gum polysaccharides are derived from renewable sources. They are readily available, inexpensive, non-hazardous and eco-friendly. Depending upon the source, gums may be categorized as microbial gums, plant exudate gums or seed gums. Naturally occurring gum carbohydrates find multiple applications in the biomedical arena, compared with synthetic compounds, because of their unique structures and functionalities. Gums and their biocomposites are preferred for sustained drug delivery because they are safe and edible as well as more susceptible to biodegradation. The present review provides a state-of-the-art conspectus on the industrial and biomedical applications of antimicrobial gum-based biocomposites. Different kinds of gums polysaccharides will first be addressed based on their sources. Metal-, carbon- and organic-based nanostructures that are used in gum nanocomposites will then be reviewed with respect to their industrial and biomedical applications, to provide a backdrop for future research.

Understanding the electrode reaction process of dechlorination of 2,4-dichlorophenol over Ni/Fe nanoparticles: Effect of pH and 2,4-dichlorophenol concentration

Herein, with the exploitation of iron and nickel electrodes, the 2,4-dichlorophenol (2,4-DCP) dechlorinating processes at the anode and cathode, respectively, were separately studied via various electrochemical techniques (e.g., Tafel polarization, linear polarization, electrochemical impedance spectroscopy). With this in mind, Ni/Fe nanoparticles were prepared by chemical solution deposition, and utilized to test the dechlorination activities of 2,4-DCP over a bimetallic system. For the iron anode, the results showed that higher 2,4-DCP concentration and solution acidity aggravated the corrosion within the electrode. The charge transfer resistance (R_ct) values of the iron electrode were 703, 473, 444, and 437 Ω∙cm² for the initial 2,4-DCP concentrations of 0, 20, 50, and 80 mg/L, respectively. When the bulk pH of the 2,4-DCP solution varied from 3.0, 5.0 to 7.0, the corresponding R_ct values were 315, 376, and 444 Ω∙cm², respectively. For the nickel cathode, the reduction current densities on the electrode at -0.75 V (vs. saturated calomel electrode) were 80, 106, and 111 μA/cm², for initial 2,4-DCP concentrations of 40, 80, and 125 mg/L. The dechlorination experiments demonstrated that when the initial pH of the solution was 7.0, 5.0, and 3.0, the dechlorination percentage of 2,4-DCP by Ni/Fe nanoparticles was 62%, 69%, and 74%, respectively, which was in line with the electrochemical experiments. 10 wt.% Ni loading into Ni/Fe bimetal was affordable and gave a good dechlorination efficiency of 2,4-DCP, and fortunately the Ni/Fe nanoparticles remained comparatively stable in the dechlorination processes at pH 3.0.

Simultaneous adsorption and degradation of triclosan by Ginkgo biloba L. stabilized Fe/Co bimetallic nanoparticles

Triclosan (TCS), an antimicrobial agent added in many pharmaceutical and personal care products, can cause some environmental problems due to its bioaccumulation, toxicity and potential antibiotic cross-resistance. In this study, Ginkgo biloba L. leaf extract was used as the green stabilizing agent to synthesize Fe/Co bimetallic nanoparticles (G-Fe/Co NPs), which were applied to remove TCS from aqueous solution. G-Fe/Co NPs were characterized by TEM, EDS, SEM, BET, FTIR, XRD and XPS. G. biloba L. leaf extract improved the dispersion and reduced the passivation of NPs. The TCS removal efficiency followed the order of G-Fe/Co NPs > G-Fe NPs > Co NPs > Fe/Co NPs > Fe NPs. G-Fe/Co NPs can be reused at least eight times. The Co leaching under different initial pH values was negligible. The factors affecting the TCS removal were investigated. The results indicated that the removal of TCS followed pseudo-second-order kinetics, and the removal rate constant decreased with increasing the initial pH value and the initial TCS concentration, and decreasing the Co loading of G-Fe/Co NPs and NPs dosage. The mass balance of TCS removal by G-Fe/Co NPs indicated that adsorption was dominant process and TCS degradation was an accumulative process.

PEGylation of zinc nanoparticles amplifies their ability to enhance olfactory responses to odorant

Olfactory responses are intensely enhanced with the addition of endogenous and engineered primarily-elemental small zinc nanoparticles (NPs). With aging, oxidation of these Zn nanoparticles eliminated the observed enhancement. The design of a polyethylene glycol coating to meet storage requirements of engineered zinc nanoparticles is evaluated to achieve maximal olfactory benefit. The zinc nanoparticles were covered with 1000 g/mol or 400 g/mol molecular weight polyethylene glycol (PEG). Non-PEGylated and PEGylated zinc nanoparticles were tested by electroolfactogram with isolated rat olfactory epithelium and odorant responses evoked by the mixture of eugenol, ethyl butyrate and (±) carvone after storage at 278 K (5 ^oC), 303 K (30 ^oC) and 323 K (50 ^oC). The particles were analyzed by atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and laser Doppler velocimetry. Our data indicate that stored ZnPEG400 nanoparticles maintain physiologically-consistent olfactory enhancement for over 300 days. These engineered Nanoparticles support future applications in olfactory research, sensitive detection, and medicine.