Insight into molecular structures and dynamical properties of niosome bilayers containing melatonin molecules: a molecular dynamics simulation approach.

Niosomes represent vesicular carriers capable of encapsulating both hydrophobic and hydrophilic drugs within their inner core or bilayer shell. They are typically composed of non-ionic synthetic surfactants such as sorbitan monostearate (Span60) with the addition of cholesterol (Chol). The physical properties and stability of niosomal vesicles strongly depend on the composition of their bilayers, which plays a significant role in determining the efficiency of drug encapsulation and release in drug delivery systems. In this study, we have explored the interactions between melatonin (Mel) molecules and the niosome bilayer, as well as their resulting physical properties. Molecular dynamics simulations were employed to investigate melatonin-inserted niosome bilayers, both with and without the inclusion of cholesterol. The simulation results revealed that cholesterol notably influences the location of melatonin molecules within the niosome bilayers. In the absence of cholesterol, melatonin tends to occupy the region around the Span60 tail groups. However, in the presence of cholesterol, melatonin is found in the vicinity of the Span60 head groups. Melatonin molecules in niosome bilayers without cholesterol exhibit a more ordered orientation when compared to those in bilayers containing 50 mol% cholesterol. The bilayer structure of the Span60/Mel and Span60/Chol/Mel systems exhibited a liquid-disordered phase (Ld). In contrast, the Span60/Chol bilayer system displays a liquid-ordered phase (Lo) with less fluidity. This study reveals that melatonin induces a disorderly bilayer structure and greater lateral expansion, whereas cholesterol induces an orderly bilayer structure and a more condensed effect. Cholesterol plays a crucial role in condensing the bilayer structure with stronger interactions between Span60 and cholesterol. The addition of 50 mol% cholesterol in the Span60 bilayers not only enhances the stability and rigidity of niosomes but also facilitates the easier release of melatonin from the bilayer membranes. This finding is particularly valuable in the context of preparing niosomes for drug delivery systems.

Fabrication and thermoelectric conversion of thermoelectric concrete brick with buried unileg N-type CaMnO3 thermoelectric module inside.

To investigate the effect of heat loss reduction due to thermal insulator and thermal interface resistance due to multi-layer structure in order to improve the efficiency of a thermoelectric device, a thermoelectric concrete brick was fabricated using a unileg n-type CaMnO3 thermoelectric module inside. CaMnO3 thermoelectric materials were synthesized by starting materials CaCO3 and MnO2 to produce a unileg n-type CaMnO3 module. Thermoelectric concrete brick consisted of two types: I-layer brick (one layer of concrete thermal insulator) and III-layer brick (three layers of different concrete insulators). The occurring temperature difference, electric current and voltage on the CaMnO3 module and thermoelectric concrete brick were measured in closed and open circuits. The temperature difference, thermal distribution, and output voltage when applying constant temperatures of 100, 200 and 400 °C were measured. Computer simulations of the Finite Element Method (FEM) were performed to compare with the experimental results. The trends of the temperature difference and the output voltage from the experimental and computer simulations were in good agreement. The results of the temperature difference during the hotter side temperature of 200 °C exhibited the temperature difference along the vertical direction of the thermoelectric concrete bricks for both types of the III-layer brick of 172 °C and the I-layer brick of 132 °C are larger than that of the CaMnO3 TEG module without using a thermal concrete insulator of 108 °C. The thermoelectric concrete bricks of the III-layer brick type of 27.70 mV displayed output voltage results being higher than those of the I-layer brick of 26.57 mV and the CaMnO3 TEG module without using a thermal concrete insulator of 24.35 mV. Thermoelectric concrete brick of the III-layer brick type displayed higher electric generation power than the I-layer brick and the CaMnO3 TEG module. Additionally, the results exhibited the capability of thermoelectric concrete brick in the III-layer brick model for electric generation power based on the temperature difference. The TEG concrete brick of I-layer concrete covering the series-parallel combination circuit of 120 modules of the unileg n-type CaMnO3 was constructed and then embedded on the outer surface of the furnace. During the maximum hotter side temperature of 580 °C of the concrete brick, the temperature difference between the hotter side and the cooler side of the brick occurred at 365 °C and the maximum output voltage was obtained at 581.7 mV.

Enhanced Electrochemical Performance of Sugarcane Bagasse-Derived Activated Carbon via a High-Energy Ball Milling Treatment.

Activated carbon (AC) from sugarcane bagasse was prepared using dry chemical activation with KOH. It was then subjected to a high-energy ball milling (HEBM) treatment under various milling speeds (600, 1200 and 1800 rpm) to produce AC nanoparticles from micro-size particles. The AC samples after the HEBM treatment exhibited reduced particle sizes, increased mesopore volume and a rich surface oxygen content, which contribute to higher pseudocapacitance. Notably, different HEBM speeds were used to find a good electrochemical performance. As a result, the AC/BM12 material, subjected to HEBM at 1200 rpm for 30 min, exhibited the highest specific capacitance, 257 F g-1, at a current density 0.5 A g-1. This is about 2.4 times higher than that of the AC sample. Moreover, the excellence capacitance retention of this sample was 93.5% after a 3000-cycle test at a current density of 5 A g-1. Remarkably, a coin cell electrode assembly was fabricated using the AC/BM12 material in a 1 M LiPF6 electrolyte. It exhibited a specific capacitance of 110 F g-1 with a high energy density of 27.9 W h kg-1.

Microporous carbon in the selective electro-oxidation of molecular biomarkers: uric acid, ascorbic acid, and dopamine.

Herein, we demonstrate the superior electrocatalytic activities of microporous carbon in the oxidation of three molecular biomarkers, ascorbic acid (AA), dopamine (DA), and uric acid (UA), which are co-present in biological fluids. The voltammetric responses of AA, DA, and UA at the low-cost microporous carbon electrode show significantly better sensitivity and selectivity than other more expensive and commonly used electrode materials such as copper(ii) oxide, copper(i) oxide, and carbon nanotube. Differential pulse voltammetry at the microporous carbon electrode allows the detection of AA, DA, and UA with linear ranges of 100-2000 µM (AA), 10-150 µM (DA), and 10-150 µM (UA), sensitivities of 6.8 ± 0.2 nA µM-1 (AA), 261.4 ± 3.4 nA µM-1 (DA), and 93.5 ± 2.0 nA µM-1 (UA), and detection limits of 23.1 µM (AA), 0.2 µM (DA), and 1.7 µM (UA). The method has been validated with a synthetic urine sample to yield ∼100% recoveries for all three analytes. The developed method has been further applied in the investigation of the peroxide scavenging activity of UA.

Fabrication of Piezoelectric Electrospun Termite Nest-like 3D Scaffolds for Tissue Engineering.

A high piezoelectric coefficient polymer and biomaterial for bone tissue engineering- poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-has been successfully fabricated into 3D scaffolds using the wet electrospinning method. Three-dimensional (3D) scaffolds have significant advantages for tissue engineering applications. Electrospinning is an advanced method and can fabricate 3D scaffolds. However, it has some limitations and is difficult to fabricate nanofibers into 3D shapes because of the low controllability of porosity and internal pore shape. The PVDF-HFP powders were dissolved in a mixture of acetone and dimethylformamide with a ratio of 1:1 at various concentrations of 10, 13, 15, 17, and 20 wt%. However, only the solutions at 15 and 17 wt% with optimized electrospinning parameters can be fabricated into biomimetic 3D shapes. The produced PVDF-HFP 3D scaffolds are in the cm size range and mimic the structure of the natural nests of termites of the genus Apicotermes. In addition, the 3D nanofiber-based structure can also generate more electrical signals than the conventional 2D ones, as the third dimension provides more compression. The cell interaction with the 3D nanofibers scaffold was investigated. The in vitro results demonstrated that the NIH 3T3 cells could attach and migrate in the 3D structures. While conventional electrospinning yields 2D (flat) structures, our bio-inspired electrospun termite nest-like 3D scaffolds are better suited for tissue engineering applications since they can potentially mimic native tissues as they have biomimetic structure, piezoelectric, and biological properties.

Molecular insight on the formation structure and dynamics of melatonin in an aqueous solution and at the Water-Air interface: A molecular dynamics study.

Melatonin is a natural hormone that has been shown highly antioxidant effects. Consequently, it has been extensively studied for its therapeutic potential in several diseases such as insomnia, cardiovascular, Alzheimer, and certain types of cancers. Recently, it has been used to adjuvant treatment for COVID-19 patients. It is well-known that melatonin is highly hydrophobic, resulting in lower solubility. However, the molecular structure and dynamic behavior of the formation of melatonin in an aqueous solution and at the water-air interface have not yet been clearly explained. This information is necessary for the melatonin formulation in drug delivery systems. The present work focuses on the molecular structure and dynamics of melatonin molecules in the aqueous solution and at the water-air interface based on using a molecular dynamics simulation study. The results showed that most melatonin molecules were aggregated in an aqueous solution while they were formed a self-assembled monolayer with the ordered structure at the water-air interface. The strong interaction of melatonin depends on their functional group which showed a similar trend for both systems and was sequenced as follows: carbonyl O > indole NH > amide NH > methoxy OA, respectively. However, the carbonyl O and the indole NH groups exhibit strong interactions with water molecules at the interface. Consequently, the two preferred orientations of the melatonin head group can be observed at the water-air interface (i.e., one is to turn the head group to the water surface with the tilted angle of ~40°-60° and the second one is to turn the head group away from the water surface with the tilted angle of ~130°). The longer lifetime of hydrogen bonds formed between melatonin themselves in the bulk water reveals that the stability of melatonin aggregation in an aqueous solution is more stable. Therefore, melatonin has less soluble in an aqueous solution.

Effect of free oxygen radical anions and free electrons in a Ca12Al14O33 cement structure on its optical, electronic and antibacterial properties.

The aim of this work was to investigate the effect of free oxygen radicals and free electrons in a Ca12Al14O33 (C12A7) cement structure on the optical, electronic and antibacterial activity of this material. Ca12Al14O33 was successfully fabricated via rapid heating to high temperatures by high frequency electromagnetic induction. Ca12Al14O33 cement samples were characterized using XRD and UV-Vis-DRS spectroscopy. The morphology and chemical composition of the samples were also investigated using SEM and EDS techniques. The presence of free oxygen radicals (O2 -ions) in the insulating structure of Ca12Al14O33 was confirmed using Raman spectroscopy showing a spectrum peak at 1067 cm-1. The excitation of free electrons in the Ca12Al14O33 cement was indicated by UV-Vis absorption spectra at 2.8 eV and an optical energy gap of 3.5 eV, which is consistent with the first-principles calculations for the band energy level. The effects of free oxygen radicals and free electrons in the Ca12Al14O33 structure as antibacterial agents against Escherichia Coli (E. coli) and Staphylococcus Aureus (S. aureus) were investigated using an agar disk-diffusion method. The presence of O2 - anions as a reactive oxygen species (ROS) at the surface of Ca12Al14O33 caused inhibition of E. coli and S. aureus cells. The free electrons in the conducting C12A7 reacted with O2 gas to produce ROS, specifically super oxides (O2 -), superoxide radicals (O2 •-), hydroxyl radicals (OH•) and hydrogen peroxide (H2O2), which exhibited antibacterial properties. Both mechanisms were active against bacteria without effects from nano-particle sized materials and photocatalytic activity. The experimental results showed that the production of ROS from free electrons was greater than that of the free O2 - anions in the structure of Ca12Al14O33. The antibacterial actions for insulating and conducting Ca12Al14O33 were different for E. coli and S. aureus. Thus, Ca12Al14O33 cement has antibacterial properties that do not require the presence of nano-particle sizes materials or photocatalysis.

Nanopriming technology for enhancing germination and starch metabolism of aged rice seeds using phytosynthesized silver nanoparticles.

Application of nanomaterials for agriculture is relatively new as compared to their use in biomedical and industrial sectors. In order to promote sustainable nanoagriculture, biocompatible silver nanoparticles (AgNPs) have been synthesized through green route using kaffir lime leaf extract for use as nanopriming agent for enhancing seed germination of rice aged seeds. Results of various characterization techniques showed the successful formation of AgNPs which were capped with phytochemicals present in the plant extract. Rice aged seeds primed with phytosynthesized AgNPs at 5 and 10 ppm significantly improved germination performance and seedling vigor compared to unprimed control, AgNO3 priming, and conventional hydropriming. Nanopriming could enhance α-amylase activity, resulting in higher soluble sugar content for supporting seedlings growth. Furthermore, nanopriming stimulated the up-regulation of aquaporin genes in germinating seeds. Meanwhile, more ROS production was observed in germinating seeds of nanopriming treatment compared to unprimed control and other priming treatments, suggesting that both ROS and aquaporins play important roles in enhancing seed germination. Different mechanisms underlying nanopriming-induced seed germination were proposed, including creation of nanopores for enhanced water uptake, rebooting ROS/antioxidant systems in seeds, generation of hydroxyl radicals for cell wall loosening, and nanocatalyst for fastening starch hydrolysis.

Charge storage mechanisms of manganese oxide nanosheets and N-doped reduced graphene oxide aerogel for high-performance asymmetric supercapacitors.

Although manganese oxide- and graphene-based supercapacitors have been widely studied, their charge storage mechanisms are not yet fully investigated. In this work, we have studied the charge storage mechanisms of K-birnassite MnO2 nanosheets and N-doped reduced graphene oxide aerogel (N-rGOae) using an in situ X-ray absorption spectroscopy (XAS) and an electrochemical quart crystal microbalance (EQCM). The oxidation number of Mn at the MnO2 electrode is +3.01 at 0 V vs. SCE for the charging process and gets oxidized to +3.12 at +0.8 V vs. SCE and then reduced back to +3.01 at 0 V vs. SCE for the discharging process. The mass change of solvated ions, inserted to the layers of MnO2 during the charging process is 7.4 µg cm-2. Whilst, the mass change of the solvated ions at the N-rGOae electrode is 8.4 µg cm-2. An asymmetric supercapacitor of MnO2//N-rGOae (CR2016) provides a maximum specific capacitance of ca. 467 F g-1 at 1 A g-1, a maximum specific power of 39 kW kg-1 and a specific energy of 40 Wh kg-1 with a wide working potential of 1.6 V and 93.2% capacity retention after 7,500 cycles. The MnO2//N-rGOae supercapacitor may be practically used in high power and energy applications.

Environmentally benign synthesis of phytochemicals-capped gold nanoparticles as nanopriming agent for promoting maize seed germination.

Application of nanotechnology in agriculture is moving towards to improve the cultivation and growth of crop plants. The present study is the first attempt to propose a simple, yet cost-effective and ecofriendly synthesis of phytochemicals-capped GNPs using rhizome extract of galanga plant at room temperature. The synthesized GNPs were characterized by various characterization techniques. To promote the green nanotechnology applications in agriculture, GNPs solution at environmentally realistic dose (5 to 15ppm) as nanopriming agent was used to activate the germination and early seedling growth of maize aged seeds. Priming with 5ppm GNPs showed the best effects on promoting emergence percentage (83%) compared to unprimed control (43%) and hydroprimed groups (56%). Seed priming at both 5 and 10ppm GNPs also enhanced seedling vigor index by 3 times over the control. Priming with GNPs at 10ppm was found to enhance the best physiological and biochemical properties of maize seedlings. Internalization studies by inductively coupled plasma atomic emission spectroscopy (ICP-OES) and transmission electron microscopy (TEM) strongly supported that GNPs can internalize into seeds. However, ICP-OES analysis revealed that GNPs were not present in both shoot and root parts, suggesting that nanopriming approach minimizes the Au translocation from seeds into plant vegetative organs. Phytosynthesized GNPs were found to be less toxic than chemically synthesized GNPs. This is the first report showing phytochemicals-capped GNPs as a promising nanopriming agent for activating the germination of naturally aged seeds of crop plant.

Polymerized Complex Synthesis and Effect of Ti Dopant on Magnetic Properties of LaFeO3 Nanoparticles.

Structure, characterization, and magnetic properties of Ti-doped LaFeO3 (LaFe(1-x)Ti(x)O3, x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) nanoparticles synthesized by polymerized complex method are investigated. All LaFe(1-x)Ti(x)O3 nanoparticles were successfully obtained from calcination of the precursor at 1050 degrees C in air for 2 h. The calcined LaFe(1-x)Ti(x)O3 samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge spectroscopy (XANES) and vibrating sample magnetometry (VSM). The XRD and TEM results showed that all LaFe(1-x)Ti(x)O3 samples had a single phase nature with the orthorhombic structure. The valence states were mixed in the Fe3+ and Fe4+ state for Fe ions and Ti4+ state for Ti ions, as confirmed by XPS and XANES results. The weak ferromagnetic behavior with the highest magnetization (M) of -0.23 emu/g at 10 kOe was obtained for x = 0.4. The origin of the ferromagnetism (FM) for all LaFe1-x)Ti(x)O3 samples supports the magnetic coupling between Fe3+ and Fe4+ ions via double exchange (DE) interaction.

The DC Bias Voltage Effect and Non-Linear Dielectric Properties of Titanate Nanotubes.

This work reports the nonlinear current-voltage behavior and the effects of dc bias voltage on the dielectric and electrical properties of titanate nanotubes (TNTs) prepared by hydrothermal method at 130 degrees C for 24 h. The TNTs sample exhibited high dielectric constant of > 10(4) at 100 Hz at room temperature with slight dependence on frequency in the range of 10(2)-10(4) Hz. The external resistance forms at the interface between electrode and surface sample. It was found that the dielectric constant of the sample decreased with increasing dc bias voltage due to the decrease in the electrode capacitance. For the study of the non-linear dielectric properties, the breakdown electric field (E(b)) value of the prepared TNTs sample obtained with J = 1 mA cm(-1) was found to be 149 V cm(-1). The E(b) value of the sample was significantly decreased with increasing temperature. The non-ohmic behavior tends to become linear ohmic in characteristic as the temperature increased.

Local Structure Determination of Carbon/Nickel Ferrite Composite Nanofibers Probed by X-ray Absorption Spectroscopy.

Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS).

Dramatically enhanced non-Ohmic properties and maximum stored energy density in ceramic-metal nanocomposites: CaCu3Ti4O12/Au nanoparticles.

Non-Ohmic and dielectric properties of a novel CaCu3Ti4O12/Au nanocomposite were investigated. Introduction of 2.5 vol.% Au nanoparticles in CaCu3Ti4O12 ceramics significantly reduced the loss tangent while its dielectric permittivity remained unchanged. The non-Ohmic properties of CaCu3Ti4O12/Au (2.5 vol.%) were dramatically improved. A nonlinear coefficient of ≈ 17.7 and breakdown electric field strength of 1.25 × 104 V/m were observed. The maximum stored energy density was found to be 25.8 kJ/m3, which is higher than that of pure CaCu3Ti4O12 by a factor of 8. Au addition at higher concentrations resulted in degradation of dielectric and non-Ohmic properties, which is described well by percolation theory.

Synthesis, characterization, and magnetic properties of monodisperse CeO2 nanospheres prepared by PVP-assisted hydrothermal method.

Ferromagnetism was observed at room temperature in monodisperse CeO2 nanospheres synthesized by hydrothermal treatment of Ce(NO3)3·6H2O using polyvinylpyrrolidone as a surfactant. The structure and morphology of the products were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and field-emission scanning electron microscopy (FE-SEM). The optical properties of the nanospheres were determined using UV and visible spectroscopy and photoluminescence (PL). The valence states of Ce ions were also determined using X-ray absorption near edge spectroscopy. The XRD results indicated that the synthesized samples had a cubic structure with a crystallite size in the range of approximately 9 to 19 nm. FE-SEM micrographs showed that the samples had a spherical morphology with a particle size in the range of approximately 100 to 250 nm. The samples also showed a strong UV absorption and room temperature PL. The emission might be due to charge transfer transitions from the 4f band to the valence band of the oxide. The magnetic properties of the samples were studied using a vibrating sample magnetometer. The samples exhibited room temperature ferromagnetism with a small magnetization of approximately 0.0026 to 0.016 emu/g at 10 kOe. Our results indicate that oxygen vacancies could be involved in the ferromagnetic exchange, and the possible mechanism of formation was discussed based on the experimental results.

CaCu3Ti4O12 nanoparticles using polyvinyl pyrrolidone: synthesis and dielectric properties.

Nanocrystalline CaCu3Ti4O12 powders with particle sizes of 39.28 8.12 nm were synthesized by a simple modify sol-gel using PVP (Poly-vinyl-pyrrolidone). The synthesized precursor was characterized by TG-DTA to determine the thermal decomposition and crystallization temperature which was found to be at above 500 degrees C. The precursor was calcined at 800 degrees C in air for 8 h to obtain nanocrystalline powders of CaCu3Ti4O12. The calcined CaCu3Ti4O12 powders were characterized by XRD, FTIR, SEM and TEM. Sintering of the powders was conducted in air at 1100 degrees C for 16 h. The XRD results indicated that all sintered samples have a typical perovskite CaCu3Ti4O12 structure and a small amount of CaTiO3. SEM micrographs showed the average grain sizes of 1.86 +/- 0.69 /m for the sintered CaCu3Ti4O12 ceramic prepared using the CaCu3Ti4O12 powders calcined at 800 degrees C. The sintered samples exhibit a giant dielectric constant, epsilon' of approximately 10(3)-10(4). The large low-frequency dielectric permittivity at low temperature is closely related to sub-grain boundary distribution, including conductivity effect. Furthermore, the ceramic shows three semicircles in the complex impedance plane. However, at low frequency, semicircles of sub-grain boundary and grain boundary are considered to represent collapse different electrical mechanisms. The another is ascribed to the contribution of grain. The dielectric behavior at several frequencies and temperatures of these samples can be attributed to electronic inhomogeneities present in material and can be explained based on a microstructural model.

Synthesis and structure analysis of La0.5SR0.5TiO3 nanoparticles prepared by thermal decomposition method.

La0.5Sr0.5TiO3 (LSTO) nanoparticles were synthesized by thermal decomposition method using Cl3La, CI2Sr x 6H2O and C16H28O6Ti as starting materials. The obtained precursor in a powder form was calcined at 700, 900, 1100 and 1300 degrees C for 3, 6 and 9 h in air. The structures of all samples were analyzed by XRD and some of them were taken for SEM, TEM and VSM measurements. The results from SEM showed the parallelpipe like shape of the particles with sizes distributed between 80 and 180 nm and the sizes of these particles were increased with the increasing of calcination temperature and time. The XRD's results showed the perovskite structure with the lattice type of orthorhombic at the calcination temperature of 900, 1100 and 1300 degrees C for 3, 6 and 9 h. The TiO and others unknown phase were found at low calcination temperature and they were disappeared as the calcination temperature and time were increased. The results of TEM support the orthorhombic structure of LSTO nanoparticles with crystallite size less than 200 nm as revealed by SEM and XRD. The magnetic property of all samples was measured by VSM and revealed that those prepared at 700, 900, and 1100 degrees C exhibit diamagnetic behavior, whereas one at 1300 shows ferromagnetism at room temperature. In this work, it is found that the nano-LSTO of high crystalline phase and purity can be prepared by thermal decomposition method at calcination temperature of 900 to 1300 degrees C in air for 6-9 h.

Synthesis and characterization of high purity hydroxyapatite nanorods by hydrothermal technique.

High purity hydroxyapatite (HAp) nanorods were synthesized by hydrothermal technique using Ca(NO3)2 x 4H2O and (NH4)2HPO4 as starting materials in a hydrothermal reactor at 150-200 degrees C for 12-24 h with pH6 and pH9.5, respectively. The prepared HAp nanorods were characterized by XRD, FTIR, and TEM techniques. The XRD results confirmed the formation of pure phase of HAp at pH9.5. With increasing temperature and time, the crystallinity of the HAp was increased, showing the hexagonal structure of HAp with the lattice parameter a in a range of 1.144-1.148 nm and c of 0.723-0.724 nm. The crystalline sizes of the powders were found to be 44-85 nm as evaluated by the XRD line broadening technique. The chemical compositions of the HAp nanorods were characterized by FTIR spectroscopies. The peaks of the phosphate carbonate and hydroxyl vibration modes were observed in the FTIR spectra for all the samples. The morphology of the HAp was nanorods of diameter less than 100 nm, as revealed by TEM. Increasing the temperature and time resulted in the transition from polycrystalline to single crystalline phase of the HAp, as clearly confirmed by the analysis of TEM diffraction patterns.

Alternative biomaterials: natural, non-woven, fibroin-based silk nanofibers of weaver ants (Oecophylla smaragdina).

Silks of silkworms and spiders have been widely studied as biomaterials, however, none has been reported on silks produced by weaver ants (Oecophylla smaragdina). This study is the first to report on some properties of natural silk fibers of weaver ants and their potential application as a cell matrix. Weaver ant fibrous mat contained non-woven mesh of fibers with diameters ranging from 266 to 3056 nm. The average diameter of fibers was 766+/-326 nm. The thickness, mass, and apparent density of the fibrous mats were 39.0+/-9.8 microm, 0.8+/-0.1 mg/cm2, and 0.22+/-0.03 g/cm3, respectively. Freshly made fibrous mats by weaver ants were highly hydrophilic as determined by water contact angle analysis, whereas older ones were quite hydrophobic. TG-DTA analysis revealed a major weight loss peak from 260 up to about 330 degrees C, similar to the decomposition peak of Bombyx mori fibroin. FT-IR spectrum showed amide I, amide II, amide III, C-H and C-O peaks, which were attributed to random coil and beta-sheet conformation in the protein structure of the weaver ant fibers. The fibrous mat was slight toxic to the fibroblast NIH 3T3 cells (37.8% cell death), probably due to some toxic particles deposited on the fibers. Nevertheless, weaver ant fibrous mat served as a good matrix for cell adhesion. Results of this work provided evidence for the properties and a potential application of natural weaver ant fibers as an alternative, natural, fibroin-based matrix.

Different properties of electrospun fibrous scaffolds of separated heavy-chain and light-chain fibroins of Bombyx mori.

This study is the first to report on the fabrication and properties of electrospun scaffolds derived from separated light-chain fibroin and heavy-chain fibroin, two major proteins of silk fibroin. Among seven different extraction conditions, which were commonly used to extract fibroin from cocoons of Bombyx mori, only Ajisawa's reagent and 9 M lithium thiocyanate could extract both heavy-chain fibroin and light-chain fibroin, while the other conditions could yield only the light-chain fibroin. Mixed fibroin, light-chain fibroin, and heavy-chain fibroin were fabricated using electrospinning methods. Average diameters of the fibers were 658+/-208, 517+/-162, and 518+/-171 nm, respectively and their sizes after treatment with 50% methanol for 60 min were slightly increased to 747+/-244, 556+/-164 and 521+/-201 nm, respectively. FTIR spectra showed similar predominant beta-sheet conformation of mixed fibroin and heavy-chain fibroin scaffolds after treated with methanol, whereas the predominant structure of light-chain fibroin was random coil conformation. Although, scaffolds derived from mixed fibroin and heavy-chain fibroin showed similar properties, the light-chain fibroin scaffold clearly exhibited different properties, including more hydrophilic character, water uptake ability, degradation rate, and cell adhesion capability.