Utilization of shea butter waste-derived hierarchical activated carbon for high-performance supercapacitor applications.

In this work, carbonization and subsequent activation procedures were adopted to synthesize waste shea butter shells into oxygen-rich interconnected porous activated carbon (SAC_x, x is the mass ratio of KOH used for activation). The SAC_1.5 electrode material showed outstanding electrochemical performance with high specific capacitance (286.6F/g) and improved rate capability, owing to various synergistic effects originating from a high specific surface area (1233.5 m2/g) and O-rich content. The SAC_1.5-based symmetric device delivered an impressive specific capacitance of 91.6F/g with a high energy density of 12.7 Wh/kg at 0.5 A/g. The device recorded 99.9 % capacitance retention after 10,000 charge-discharge cycles. The symmetric supercapacitor device successfully lit an LED bulb for more than 1 h, signifying the potential of bio-waste as an efficient carbon precursor for electrode material in practical supercapacitors. This work offers an efficient, affordable, and environmentally friendly strategy for potential renewable energy storage devices.

Optimum iron-pyrophosphate electronic coupling to improve electrochemical water splitting and charge storage.

Tuning the electronic properties of transition metals using pyrophosphate (P2O7) ligand moieties can be a promising approach to improving the electrochemical performance of water electrolyzers and supercapacitors, although such a material's configuration is rarely exposed. Herein, we grow NiP2O7, CoP2O7, and FeP2O7 nanoparticles on conductive Ni-foam using a hydrothermal procedure. The results indicated that, among all the prepared samples, FeP2O7 exhibited outstanding oxygen evolution reaction and hydrogen evolution reaction with the least overpotential of 220 and 241 mV to draw a current density of 10 mA/cm2. Theoretical studies indicate that the optimal electronic coupling of the Fe site with pyrophosphate enhances the overall electronic properties of FeP2O7, thereby enhancing its electrochemical performance in water splitting. Further investigation of these materials found that NiP2O7 had the highest specific capacitance and remarkable cycle stability due to its high crystallinity as compared to FeP2O7, having a higher percentage composition of Ni on the Ni-foam, which allows more Ni to convert into its oxidation states and come back to its original oxidation state during supercapacitor testing. This work shows how to use pyrophosphate moieties to fabricate non-noble metal-based electrode materials to achieve good performance in electrocatalytic splitting water and supercapacitors.

Bimetallic Co-Fe sulfide and phosphide as efficient electrode materials for overall water splitting and supercapacitor.

The major center of attraction in renewable energy technology is the designing of an efficient material for both electrocatalytic and supercapacitor (SC) applications. Herein, we report the simple hydrothermal method to synthesize cobalt-iron-based nanocomposites followed by sulfurization and phosphorization. The crystallinity of nanocomposites has been confirmed using X-ray diffraction, where crystalline nature improves from as-prepared to sulfurized to phosphorized. The as-synthesized CoFe-nanocomposite requires 263 mV overpotential for oxygen evolution reaction (OER) to reach a current density of 10 mA/cm2 whereas the phosphorized requires 240 mV to reach 10 mA/cm2. The hydrogen evolution reaction (HER) for CoFe-nanocomposite exhibits 208 mV overpotential at 10 mA/cm2. Moreover, the results improved after phosphorization showing 186 mV to reach 10 mA/cm2. The specific capacitance (Csp) of as-synthesized nanocomposite is 120 F/g at 1 A/g, along with a power density of 3752 W/kg and a maximum energy density of 4.3 Wh/kg. Furthermore, the phosphorized nanocomposite shows the best performance by exhibiting 252 F/g at 1 A/g and the highest power and energy density of 4.2 kW/kg and 10.1 Wh/kg. This shows that the results get improved more than twice. The 97% capacitance retention after 5000 cycles shows cyclic stability of phosphorized CoFe. Our research thus offers cost-effective and highly efficient material for energy production and storage applications.

Magnetic-field-induced self-assembly of FeCo/CoFe2O4 core/shell nanoparticles with tunable collective magnetic properties.

Self-assembly of nanoparticles into ordered patterns is a novel approach to build up new consolidated materials with desired collective physical properties. Herein, nanoparticle assemblies of composition-modulated bimagnetic nanoparticles have been produced via slow evaporation of their colloidal suspension in the absence or presence of magnetic fields. The assemblies obtained in the presence of the magnetic fields exhibit oriented nanoparticle chains in face-centered cubic superlattice structures, compared with the hexagonal closed-packed superlattice obtained without the magnetic field. The oriented structure has an alignment of the easy magnetization axis along the chains. This alignment leads to enhanced intra-superlattice interactions. As a result, the field-induced assembly displays collective magnetic properties with significantly enhanced magnetic anisotropy, remanent magnetization and coercivity. It is also found that the bimagnetic FeCo/CoFe2O4 core/shell nanostructure enhances the intra-particle interaction and thus is beneficial for the growth of oriented assembly of nanoparticles. Furthermore, the collective magnetic behavior is evidenced by the observation of a superferromagnetic-like magnetization relaxation in the ac-susceptibility curves.

Enhancing the magnetic and inductive heating properties of Fe3O4 nanoparticles via morphology control.

Fe3O4 nanoparticles (NPs) with different shapes have been prepared by a 'solventless' synthesis approach to probe shape anisotropy effects on the magnetic and inductive heating properties. Various shapes including spheres, octahedrons, cubes, rods, wires, and multipods are obtained through alterations in reaction conditions such as the ratio of precursor to surfactant content and heating rate. Magnetic and Mössbauer measurements reveal better stoichiometry in anisotropic-shaped Fe3O4 NPs than that in the spherical and multipod NPs. As a result, the magnetization value of the anisotropic-shaped NPs approaches the value for bulk material (∼86 emu g-1). More surprisingly, the Verwey transition, which is a characteristic phase transition of bulk magnetite structure, is observed near 120 K in the anisotropic-shaped NPs, which further corroborates the fact that these NPs possess better stoichiometry compared to the spherical and multipod-shaped NPs. Other than the improved magnetic properties, these anisotropic-shaped NPs are more effective for hyperthermia applications. For example, compared to the conventional spherical NPs, the nanowires show much higher SAR value up to 846 W g-1, making them a potential candidate for practical hyperthermia treatment. In particular, the octahedral NPs shows an SAR value higher than the same size spherical NPs, which demonstrates the importance of occurrence of the Verwey transition in Fe3O4 NPs for better stoichiometric and higher heating.

Electric Stimulus-Responsive Chitosan/MNP Composite Microbeads for a Drug Delivery System.

In the last several years, conventional drug delivery systems (DDS) have evolved into DDS that are responsive to exogenous or endogenous stimuli. The objective of this paper is to present a DDS that is responsive to an electric stimulus in the form of bipolar electric pulses. The DDS structure is based on chitosan embedded with magnetic nanoparticles, and crosslinked with polyethylene glycol dimethacrylate to form microbeads. This DDS is loaded with vancomycin as the therapeutic agent of interest. Silver inter-digitated electrodes (IDE) were printed on polyimide substrates with a MEMS-based inkjet material deposition printer, and used to provide 100 Hz pulses of electric current to the DDS for 3 min. The results showed that the stimulated groups released ∼800% more vancomycin than the non-stimulated groups in the excitation duration, but followed a first-order elution profile otherwise. Another significance of our approach is that it does not need complicated or expensive fabrication processes, and can be customized according to the targeted implant site. The IDE system has also been modeled using COMSOL to study the distributed electric fields and ion migration during the stimulus. This paper demonstrates a novel and promising technique of providing stimulus to drug substrates for controllable drug delivery.

Once Daily Pregabalin Eye Drops for Management of Glaucoma.

Elevated intraocular pressure (IOP) is the most significant risk factor contributing to visual field loss in glaucoma. Unfortunately, the deficiencies associated with current therapies have resulted in reduced efficacy, several daily dosings, and poor patient compliance. Previously, we identified the calcium voltage-gated channel auxiliary subunit alpha2delta 1 gene (Cacna2d1) as a modulator of IOP and demonstrated that pregabalin, a drug with high affinity and selectivity for CACNA2D1, lowered IOP in a dose-dependent manner. Unfortunately, IOP returned to baseline at 6 h after dosing. In the current study, we develop a once daily topical pregabalin-loaded multiple water-in-oil-in-water microemulsion formulation to improve drug efficacy. We characterize our formulations using multiple in vitro and in vivo evaluations. Our lead formulation provides continuous release of pregabalin for up to 24 h. Because of its miniscule droplet size (<20 nm), our microemulsion has a transparent appearance and should not blur vision. It is also stable at one month of storage at temperatures ranging from 5 to 40 °C. Our formulation is nontoxic, as illustrated by a cell toxicity study and slit-lamp biomicroscopic exams. CACNA2D1 is highly expressed in both the ciliary body and the trabecular meshwork, where it functions to modulate IOP. A single drop of our lead pregabalin formulation reduces IOP by greater than 40%, which does not return to baseline until >30 h post-application. Although there were no significant differences in the amplitude of IOP reduction between the formulations we tested, a significant difference was clearly observed in their duration of action. Our multilayered microemulsion is a promising carrier that sustains the release and prolongs the duration of action of pregabalin, a proposed glaucoma therapeutic.

Size-dependent magnetic and inductive heating properties of Fe3O4 nanoparticles: scaling laws across the superparamagnetic size.

An efficient heat activating mediator with an enhanced specific absorption rate (SAR) value is attained via control of the iron oxide (Fe3O4) nanoparticle size from 3 to 32 nm. Monodispersed Fe3O4 nanoparticles are synthesized via a seed-less thermolysis technique using oleylamine and oleic acid as the multifunctionalizing agents (surfactant, solvent and reducing agent). The inductive heating properties as a function of particle size reveal a strong increase in the SAR values with increasing particle size up to 28 nm. In particular, the SAR values of ferromagnetic nanoparticles (>16 nm) are strongly enhanced with the increase of ac magnetic field amplitude than that for the superparamagnetic (3-16 nm) nanoparticles. The enhanced SAR values in the ferromagnetic regime are attributed to the synergistic contribution from the hysteresis and susceptibility loss. Specifically, the 28 nm Fe3O4 nanoparticles exhibit an enhanced SAR value of 801 W g-1 which is nearly an order higher than that of the commercially available nanoparticles.

Magnetic stimulus responsive vancomycin drug delivery system based on chitosan microbeads embedded with magnetic nanoparticles.

Local antibiotic delivery can overcome some of the shortcomings of systemic therapy, such as low local concentrations and delivery to avascular sites. A localized drug delivery system (DDS), ideally, could also use external stimuli to modulate the normal drug release profile from the DDS to provide efficacious drug administration and flexibility to healthcare providers. To achieve this objective, chitosan microbeads embedded with magnetic nanoparticles were loaded with the antibiotic vancomycin and stimulated by a high frequency alternating magnetic field. Three such stimulation sessions separated by 1.5 h were applied to each test sample. The chromatographic analysis of the supernatant from these stimulated samples showed more than approximately 200% higher release of vancomycin from the DDS after the stimulation periods compared to nonstimulated samples. A 16-day long term elution study was also conducted where the DDS was allowed to elute drug through normal diffusion over a period of 11 days and stimulated on day 12 and day 15, when vancomycin level had dropped below therapeutic levels. Magnetic stimulation boosted elution of test groups above minimum inhibitory concentration (MIC), as compared to control groups (with no stimulation) which remained below MIC. The drug release from test groups in the intervals where no stimulation was given showed similar elution behavior to control groups. These results indicate promising possibilities of controlled drug release using magnetic excitation from a biopolymer-based DDS. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2169-2176, 2018.

Eco-Friendly and High Performance Supercapacitors for Elevated Temperature Applications Using Recycled Tea Leaves.

Used tea leaves are utilized for preparation of carbon with high surface area and electrochemical properties. Surface area and pore size of tea leaves derived carbon are controlled by varying the amount of KOH as activating agent. The maximum surface area of 2532 m2 g-1 is observed, which is much higher than unactivated tea leaves (3.6 m2 g-1). It is observed that the size of the electrolyte ions has a profound effect on the energy storage capacity. The maximum specific capacitance of 292 F g-1 is observed in 3 m KOH electrolyte with outstanding cyclic stability, while the lowest specific capacitance of 246 F g-1 is obtained in 3 m LiOH electrolyte at 2 mV s-1. The tea leaves derived electrode shows almost 100% capacitance retention up to 5000 cycles of study. The symmetrical supercapacitor device shows a maximum specific capacitance of 0.64 F cm-2 at 1 mA cm-2 and about 95% of specific capacitance is retained after increasing current density to 12 mA cm-2, confirming the high rate stability of the device. An improvement over 35% in the charge storage capacity is seen when increasing device temperature from 10 to 80 °C. The study suggests that used tea leaves can be used for the fabrication of environment friendly high performance supercapacitor devices at a low cost.

Water-soluble Complex of Curcumin with Cyclodextrins: Enhanced Physical Properties For Ocular Drug Delivery.

BACKGROUND: Curcumin, a natural hydrophobic polyphenol, has been reported to have diverse pharmacological activities. Previous studies have evaluated its efficacy using both oral and transdermal dosage forms. However, two major obstacles-poor aqueous solubility and low stability-severely limited its pharmaceutical use. OBJECTIVE: The main objective of this study was to prepare curcumin eye drops that provided sustained release to allow for once daily application in retinitis pigmentosa. METHOD: To achieve our goal, curcumin was complexed with ß -cyclodextrin and hydroxypropyl-ß- cyclodextrin in two molar ratios (1:1 and 1:2) using co-solvent, co-solvent with sonication and freezedrying filtration methods. A total of 12 complexes were prepared, then characterized using differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, solubility assessment and in vitro release studies. RESULTS: An improvement in curcumin aqueous solubility relative to pure curcumin was achieved for all 12 complexes. However, the freeze-drying filtration method was superior to all other methods because it produced highly water-soluble drug-CD complexes. Based on our stability analyses, pH 6.8 phosphate buffer containing 1% Tween 80 was selected as the release medium for in vitro release studies because curcumin exhibited high stability in this medium. Our F11 formulation provided sustained release of the drug for more than 96 h with a maximum amount released of drug (21.77±0.26 µg/ml). Our in vitro release data also showed that release of drug from curcumin-CDs inclusion complexes followed a Higuchi non-Fickian diffusion mechanism. CONCLUSION: Based on these results, F11 was formulated as eye drops, which provide a promising once daily novel topical delivery of this naturally derived phytochemical.

Size- and Shape-Controlled Synthesis and Properties of Magnetic-Plasmonic Core-Shell Nanoparticles.

Magnetic-plasmonic core-shell nanomaterials offer a wide range of applications across science, engineering and biomedical disciplines. However, the ability to synthesize and understand magnetic-plasmonic core-shell nanoparticles with tunable sizes and shapes remains very limited. This work reports experimental and computational studies on the synthesis and properties of iron oxide-gold core-shell nanoparticles of three different shapes (sphere, popcorn and star) with controllable sizes (70 to 250 nm). The nanoparticles were synthesized via a seed-mediated growth method in which newly formed gold atoms were added onto gold-seeded iron oxide octahedrons to form gold shell. The evolution of the shell into different shapes was found to occur after the coalescence of gold seeds, which was achieved by controlling the amount of additive (silver nitrate) and reducing agent (ascorbic acid) in the growth solution. First principles calculation, together with experimental results, elucidated the intimate roles of thermodynamic and kinetic parameters in the shape-controlled synthesis. Both discrete dipole approximation calculation and experimental results showed that the nanopopcorns and nanostars exhibited red-shifted plasmon resonance compared with the nanospheres, with the nanostars giving multispectral feature. This research has made a great step further in manipulating and understanding magnetic-plasmonic hybrid nanostructures and will make important impact in many different fields.

Conjugation of Hot-Melt Extrusion with High-Pressure Homogenization: a Novel Method of Continuously Preparing Nanocrystal Solid Dispersions.

Over the past few decades, nanocrystal formulations have evolved as promising drug delivery systems owing to their ability to enhance the bioavailability and maintain the stability of poorly water-soluble drugs. However, conventional methods of preparing nanocrystal formulations, such as spray drying and freeze drying, have some drawbacks including high cost, time and energy inefficiency, traces of residual solvent, and difficulties in continuous operation. Therefore, new techniques for the production of nanocrystal formulations are necessary. The main objective of this study was to introduce a new technique for the production of nanocrystal solid dispersions (NCSDs) by combining high-pressure homogenization (HPH) and hot-melt extrusion (HME). Efavirenz (EFZ), a Biopharmaceutics Classification System class II drug, which is used for the treatment of human immunodeficiency virus (HIV) type I, was selected as the model drug for this study. A nanosuspension (NS) was first prepared by HPH using sodium lauryl sulfate (SLS) and Kollidon® 30 as a stabilizer system. The NS was then mixed with Soluplus® in the extruder barrel, and the water was removed by evaporation. The decreased particle size and crystalline state of EFZ were confirmed by scanning electron microscopy, zeta particle size analysis, and differential scanning calorimetry. The increased dissolution rate was also determined. EFZ NCSD was found to be highly stable after storage for 6 months. In summary, the conjugation of HPH with HME technology was demonstrated to be a promising novel method for the production of NCSDs.

Engineering Photosystem I Complexes with Metal Oxide Binding Peptides for Bioelectronic Applications.

Conventional dye-sensitized solar cells comprise semiconducting anodes sensitized with complex synthetic organometallic dyes, a platinum counter electrode, and a liquid electrolyte. This work focuses on replacing synthetic dyes with a naturally occurring biological pigment-protein complex known as Photosystem I (PSI). Specifically, ZnO binding peptides (ZOBiP)-fused PSI subunits (ZOBiP-PsaD and ZOBiP-PsaE) and TiO2 binding peptides (TOBiP)-fused ferredoxin (TOBiP-Fd) have been produced recombinantly from Escherichia coli. The MOBiP-fused peptides have been characterized via western blotting, circular dichroism, MALDI-TOF, and cyclic voltammetry. ZOBiP-PSI subunits have been used to replace wild-type PsaD and PsaE, and TOBiP-Fd has been chemically cross-linked to the stromal hump of PSI. These MOBiP peptides and MOBiP-PSI complexes have been produced and incubated with various metal oxide nanoparticles, showing increased binding when compared to that of wild-type PSI complexes.

Near-infrared-absorbing gold nanopopcorns with iron oxide cluster core for magnetically amplified photothermal and photodynamic cancer therapy.

We present the synthesis and application of a new type of dual magnetic and plasmonic nanostructures for magnetic-field-guided drug delivery and combined photothermal and photodynamic cancer therapy. Near-infrared-absorbing gold nanopopcorns containing a self-assembled iron oxide cluster core were prepared via a seed-mediated growth method. The hybrid nanostructures are superparamagnetic and show great photothermal conversion efficiency (η=61%) under near-infrared irradiation. Compact and stable nanocomplexes for photothermal-photodynamic therapy were formed by coating the nanoparticles with near-infrared-absorbing photosensitizer silicon 2,3-naphthalocyannie dihydroxide and stabilization with poly(ethylene glycol) linked with 11-mercaptoundecanoic acid. The nanocomplex showed enhanced release and cellular uptake of the photosensitizer with the use of a gradient magnetic field. In vitro studies using two different cell lines showed that the dual mode photothermal and photodynamic therapy with the assistance of magnetic-field-guided drug delivery dramatically improved the therapeutic efficacy of cancer cells as compared to the combination treatment without using a magnetic field and the two treatments alone. The "three-in-one" nanocomplex has the potential to carry therapeutic agents deep into a tumor through magnetic manipulation and to completely eradicate tumors by subsequent photothermal and photodynamic therapies without systemic toxicity.

The roles of cellular nanomechanics in cancer.

The biomechanical properties of cells and tissues may be instrumental in increasing our understanding of cellular behavior and cellular manifestations of diseases such as cancer. Nanomechanical properties can offer clinical translation of therapies beyond what are currently employed. Nanomechanical properties, often measured by nanoindentation methods using atomic force microscopy, may identify morphological variations, cellular binding forces, and surface adhesion behaviors that efficiently differentiate normal cells and cancer cells. The aim of this review is to examine current research involving the general use of atomic force microscopy/nanoindentation in measuring cellular nanomechanics; various factors and instrumental conditions that influence the nanomechanical properties of cells; and implementation of nanoindentation methods to distinguish cancer cells from normal cells or tissues. Applying these fundamental nanomechanical properties to current discoveries in clinical treatment may result in greater efficiency in diagnosis, treatment, and prevention of cancer, which ultimately can change the lives of patients.

Capture and detection of cancer cells in whole blood with magnetic-optical nanoovals.

AIM: To develop a simple assay for the capture and detection of rare cancer cells in whole blood using iron oxide-gold (IO-Au) nanoparticles. MATERIALS & METHODS: IO-Au nanoovals (NOVs) were synthesized, coated with Raman tags and linked with antibodies targeting breast cancer. An integrated system was constructed for on-line magnetic cell capture and surface-enhanced Raman scattering (SERS) detection. The capabilities of IO-Au SERS NOVs to capture and detect rare cancer cells in blood were investigated in the integrated system using circulating tumor cell-mimic SK-BR-3 cells. RESULTS: SK-BR-3 cells in whole blood were magnetically captured under a flow condition using IO-Au SERS NOVs, followed by on-line SERS detection with a limit of detection of 1-2 cells/ml blood. CONCLUSION: We developed a sensitive method that can capture and detect cancer cells in whole blood with a single nanoconstruct, which is highly promising for the detection of circulating tumor cells in the clinic.

Synergistic effect of PVP and PEG on the behavior of silver nanoparticle-polymer composites.

Silver nanoparticles-polymer nanocomposites, Ag-(1 - x)PVP-(x)PEG, were synthesized by wet chemical method in the presence of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG). A mixture of two stabilizing agent PVP and PEG is found to play a crucial role in controlling the morphology of nanocrystalline silver particles in the composite. This is inferred based on the shape and size study of nanocrystalline silver using the X-ray diffraction, transmission electron microscopy, Uv-vis spectroscopy, FTIR, and surface enhance Raman studies. These results suggest asymmetrical growth of silver nanocrystalline particles in the presence of both PVP and PEG. Comparison of the thermal properties of the Ag-polymer nanocomposites with pure polymers, PVP and PEG, showed that the thermal stability of the nanocomposite deteriorates by as much as 75 degrees C in the presence of low PEG concentration (x < or = 0.6) and improves by around 45 degrees C at higher PEG concentration (x > 0.6). The study highlight the fact that the morphology of nanocrystalline silver can be altered just by varying the polymer weight ratios rather than any processing parameters, thus offering a novel, simple, and controlled synthesis engineering route to the formation of nanocrystalline silver in polymer matrix.

Synthesis and properties of near infrared-absorbing magnetic-optical nanopins.

Novel near infrared-absorbing iron oxide-gold core-shell nanoparticles in pin shapes were synthesized. The nanopins are superparamagnetic, with 35-fold better surface enhanced Raman scattering activities than the conventional core-shell nanospheres and 50-fold greater photothermal properties than solid gold nanorods. The nanoparticles will have important impact on medical imaging, molecular diagnostics and disease treatment.

Effect of molecular weight of chitosan degraded by microwave irradiation on lyophilized scaffold for bone tissue engineering applications.

Chitosan (CTS) is biocompatible, biodegradable, and can be formed into 3D porous structures for bone tissue engineering applications. Although studies have reported on the effects of molecular weight (MW) on CTS physicochemical properties, studies evaluating CTS biological property relationships often do not account for MW that confounds interpretation of study results. The aim of this study was to evaluate the effect of MW on CTS physicochemical and biological properties. CTS materials were treated for 6, 18, and 30 min by microwave irradiation to decrease MW without affecting deacetylation (DDA). Materials were evaluated for crystallinity using X-ray diffraction, thermal degradation using differential scanning calorimetry, water content, swelling ratio, and in vitro compatibility using Saos-2. Results showed that microwave treatments did not affect DDA but decreased MW and swelling ratio by 45.78% and 36.75%, respectively, after 30 min of microwave treatment. Microwave-treated CTS showed reduced or no crystalline peaks. Initial increase in exothermic peak temperatures with short (6 min) microwave treatment times were followed by a decrease with longer (18 and 30 min) treatment times. Cell growth over 7 days on samples was proportional to MW with the number of cells being 62% higher on CTS with the highest MW (3.71 ± 0.25 × 10(5) g/mol) when compared with the lower MW CTS (2.38 ± 0.12 × 10(5) g/mol). These results demonstrate the importance of MW of CTS to both its physicochemical characteristics and biological properties, providing researchers with another tool for the modulation and optimization of CTS for different biomedical applications.