Biogenic synthesis of silver nanoparticles using Persicaria odorata leaf extract: Antibacterial,cytocompatibility, and in vitro wound healing evaluation

Biogenic synthesis of silver nanoparticles (b-AgNPs) utilising plant extract has gained the interest of researchers due to the environmentally friendly and cost-effective technique. However, the extent of its application in the biomedical field remains scarce. This study evaluates the antibacterial, cytocompatibility, and wound healing activities of synthesised AgNPs using Persicaria odorata leaves extract (PO-AgNPs). The formation of PO-AgNPs was observed by visual colour changes and verified by ultraviolet-visible (UV–vis) spectrophotometer, which revealed a surface plasmon resonance (SPR) at around 440 nm, and further confirmed by X-ray diffraction (XRD). Characterisation using Fourier transform infrared (FTIR) spectroscopy showed biomolecules from the leaves extract presented together on PO-AgNPs. Field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscopy (HR-TEM) images revealed PO-AgNPs nanospheres with diameters of 11 ± 3 nm. Disc diffusion test (DDT) and minimum inhibitory concentration (MIC) analysis resulted in a dose-dependent inhibition of PO-AgNPs against tested Staphylococcus epidermidis and Methicillin-resistant Staphylococcus aureus (MRSA). These results were further corroborated by time-kill kinetic assay which revealed that PO-AgNPs were bactericidal against both strains 24 h post-treatment. Cytocompatibility and in vitro wound healing evaluation against normal human fibroblast cells, HSF 1184 inferred that PO-AgNPs are non-toxic to normal cells and able to enhance cell migration as compared to the non-treated cells. Therefore, PO-AgNPs are biocompatible and possess antibacterial and wound healing capabilities that are useful in biomedical applications.     

Capuli cherry-mediated green synthesis of silver nanoparticles under white solar and blue LED light

In this article, the Capuli (Prunus serotina Ehrh. var. Capuli) cherry extract was used for the synthesis of silver nanoparticles (AgNPs) in the presence of white/visible solar and blue light-emitting diode (LED) light. For the characterization of the extract and the AgNPs, Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy were employed, along with hydrodynamic particle size analysis, transmission electron microscopy and X-ray diffraction. The Ag nanospheres obtained using white light were 40–100 nm in diameter and exhibited an absorption peak at λ_max = 445 nm, whereas those obtained using blue LED light were 20–80 nm in diameter with an absorption peak at λ_max = 425 nm. Thermal analysis revealed that the content of biomolecules surrounding the AgNPs was about 55–65%, and it was also found that blue LED light AgNPs (56.28%, 0.05 mM) had a higher antioxidant efficacy than the white solar light AgNPs (33.42%, 0.05 mM) against 1,1-diphenyl-2-picrylhydrazyl. The results indicate that obtaining AgNPs using a blue LED light may prove to be a simple, cost-effective and easily reproducible method for creating future nanopharmaceuticals.     

In situ biosynthesized silver nanoparticle-incorporated synthesized zeolite A using Orthosiphon aristatus extract for in vitro antibacterial wound healing

The capability of synthesized zeolite A (SZ) to immobilize Ag ions (Ag-SZ) and Ag nanoparticles (AgNp-SZ) were comparatively studied. A novel approach of in situ biosynthesized AgNP-incorporated synthesized zeolite A (AgNp-SZ) was synthesized at an optimum volume of 0.4 mL of the Orthosiphon aristatus (O. aristatus) leaves plant extract (5%) using an in situ approach. In comparison, Ag-SZ was produced by loading the synthesized zeolite with Ag ions. All synthesized materials were characterized for their morphologies and physicochemical properties. The characterization analyses validate that the biosynthesized AgNP (<100 nm) using O. aristatus leaves extract was incorporated into the zeolite A. The antibacterial testing confirmed that these materials have antibacterial activity against Escherichia coli ATCC 11229 and Staphylococcus aureus ATCC 6538. MIC/MBC analysis demonstrated that in 0.9% saline solution, AgNP-SZ had higher antibacterial activity than Ag-SZ. The in vitro cell viability and migration assays were further examined towards human skin fibroblast cells HSF 1184. Results show that the materials are not cytotoxic to HSF 1184, and the biosynthesized AgNP-SZ promotes cell migration and proliferation higher than Ag-SZ. This research proved that the biocompatible antibacterial wound healing agent of AgNP-SZ can be synthesized using an in situ approach where the reduction process of Ag ions in the zeolite A can be performed using plant extract.     

Key synthesis of magnetic Janus nanoparticles using a modified facile method

Inorganic/organic poly（methylmethacrylate-acrylic acid-divinylbenzene） iron oxide Janus magnetic nanoparticles（P（MMA-AA-DVB）/Fe3O4） with strong magnetic domains and unique surface functionalities were prepared using a solvothermal process.The P（MMA-AA-DVB） nanoparticles were prepared via soapfree emulsion polymerization and used as a precursor for preparing Janus nanoparticles.The morphology and magnetic properties of the magnetic Janus nanoparticles formed were characterized using a laser particle size analyzer,transmission electron microscopy,Fourier transform infrared spectroscopy,vibrating sample magnetometry,and thermogravimetric analysis.The synthesized P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were characterized by a Janus structure and possessed a stable asymmetric morphology after being dually functionalized.The particle size,magnetic content,and magnetic domain of the P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were 200 nm,40%,and 25 emu/g,respectively.The formation mechanism of the Janus nanoparticles was also investigated,and the results revealed that the reduction of Fe3＋ ions and growth of Fe3O4 took place on the surface of the P（MMA-AA-DVB） polymeric precursor particles.The size of the Janus particles could be controlled by narrowing the size distribution of the P（MMA-AA-DVB） precursor nanoparticles.     

Template-free approach for hydrothermal fabrication of ZnO microspheres

Wurtzite ZnO microspheres, 5.5-11 m in diameter and with smooth surfaces, were prepared in absolute ethanol via a simple template-free method in the presence of ethylenediamine. The products were characterized using X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. This simple method to fabricate ZnO microspheres shows high yield (>90%) and good repro-ducibility. The formation process of ZnO microspheres was discussed. The as-obtained ZnO microspheres are expected ...     

Continuous hydrothermal synthesis of AlO(OH) nanorods as a clean flame retardant agent

Aluminum-oxide-hydroxide (AlOOH) is a clean and non-toxic flame retardant. There have been many trials for the fabrication of ultrafine AlOOH. Two main approaches exist for nano-AlOOH synthesis: reactive precipitation and batch hydrothermal synthesis. Both approaches are laborious and time consuming with poor control of particle morphology. We report on the novel continuous flow manufacture of AlOOH nanorods with controlled morphology (particle size and shape) by hydrothermal synthesis. AlOOH was harvested from its mother liquor (colloidal solution) using poly(acrylamide-co-acrylic acid) copolymer as a flocculating agent. The developed AlOOH shape and size, crystalline phase, thermal stability, and endothermic heat sink action were investigated by transmission electron microscopy, X-ray diffractometry, thermogravimetric analysis, and differential scanning calorimetry, respectively. The phase transition of AlOOH to Al₂O₃ was demonstrated by conducting different X-ray diffractometry scans from 400 to 700 °C. These results may provide an option for the continuous synthesis of nano-AlOOH as a clean and non-toxic flame retardant with excellent thermal stability. Consequently, enhanced flammability properties can be achieved at low solids loading.     

Template-flee approach for hydrothermal fabrication of ZnO microspheres

Wurtzite ZnO microspheres, 5.5-11 μm in diameter and with smooth surfaces, were prepared in abso-lute ethanol via a simple template-free method in the presence of ethylenediamine. The products were characterized using X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. This simple method to fabricate ZnO microspheres shows high yield (>90%) and good repro-ducibility. The formation process of ZnO microspheres was discussed. The as-obtained ZnO microspheres are expected to provide some immediate advantages for optical, microelectronic, and biological applica-tions.     

Synthesis of TiO2 nanoparticles by propane/air turbulent flame CVD process

Synthesis of TiO2 nanoparticles by the oxidation of titanium tetrachloride (TiCl4) in high-strength propane/air turbulent flame is investigated tentatively for mass production ofTiO2 nanoparticles. Effects of reactor heat flux varying from 247 to 627 kJ/m2 s, initial TiO2 number density from 2×1020> to 1 × 1021 m-3, and apparent residence time of TiO2 nanoparticles in reactor from 0.06 to 0.9 s, on particle morphology, phase composition, UV absorption and photoluminescence (PL) spectra are studied. The TiO2 nanoparti-cles synthesized, with mean size of 30-80 nm and rutile mass fraction from 0.155 up to 0.575, exhibited a strong PL signal at the wavelength of 370-450 nm, with a wide peak signal at 400-420 nm, reflecting significant oxygen vacancies on the surface of the TiO2 nanoparticles.     

A novel preparation of nanosized hexagonal Mg(OH)2 as a flame retardant

Nanosized dispersive hexagonal magnesium hydroxide (Mg(OH)₂) has been prepared using an ammonia-hydrothermal method. Citric acid and monoethanolamine (MEA) were added to the reaction system during the ammonia precipitation and hydrothermal processes, respectively, to improve the crystallinity and dispersion of the (Mg(OH)₂) particles. The resulting Mg(OH)₂ samples obtained under the optimum preparation conditions were characterized by scanning electron microscopy, X-ray diffraction and thermal gravity analysis, which showed that this newly developed procedure afforded well-dispersed hexagonal nanoplates of Mg(OH)₂ with a mean diameter of 246 nm.     

Photodegradation of benzene by TiO_2 nanoparticles prepared by flame CVD process

Photodegradation of benzene at ppb levels by mixed-phase TiO 2 nanoparticles, synthesized by the oxidation of TiCl 4 in propane/air turbulent flame chemical vapor deposition (CVD) process, is investigated experimentally by using a tubular photoreactor with thin TiO 2 films coated on the reactor wall by sedimentation. Effects of inlet benzene concentration from 10 to 300 g/m 3 , rutile mass fraction from about 20 to 50% and photoluminescence (PL) intensity of TiO 2 nanoparticles on degradation degree are exa...     

Potassium sodium tartrate-assisted hydrothermal synthesis of BaLuF5:Yb3+/Er3+ nanocrystals

Highly-dispersed BaLuF₅:Yb³⁺/Er³⁺ nanocrystals were prepared by a facile potassium sodium tartrate-assisted hydrothermal method. The average particle size was approximately 20–25 nm. The formation mechanism is discussed. Potassium sodium tartrate led to form a complex with an approximately three-dimensional network structure, which insured largely concurrent nucleation. As a result, we acquired uniform nanoparticles. The hydrothermal temperature, holding time, and pH value were important factors affecting the formation of the BaLuF₅:Yb³⁺/Er³⁺ nanocrystals. We investigated their influence on the formation and realized the optimal reaction parameters. Remarkably, potassium sodium tartrate also contributed to the biocompatibility and potential biomedical applications of BaLuF₅:Yb³⁺/Er³⁺ nanocrystals by decomposing into small organic groups attached to the nanoparticles.     

Mild hydrothermal preparation of a layered metal hydroxide salt with microtube/rod morphology

Microtubes/rods of the layered metal hydroxide salt compound Cd2(OH)3(DS).nH2O, where DS stands for dodecyl sulfate sandwiched between two adjacent inorganic sheets, have been synthesized for the first time through a mild hydrothermal reaction route. The microtubes/rods have a diameter of about 1 μm and a length ranging from several microns to 20 μm. The growth process of microtubes/rods under the experimental conditions employed follows a dissolution-recrystallization route.     

Influence of disodium hydrogen phosphate dodecahydrate on hydrothermal formation of hemihydrate calcium sulfate whiskers

The influence of Na₂HPO₄·12H₂O on the hydrothermal formation of hemihydrate calcium sulfate (CaSO₄·0.5H₂O) whiskers from dihydrate calcium sulfate (CaSO₄·2H₂O) at 135 °C was investigated. Experimental results indicate that the addition of phosphorus accelerates the hydrothermal conversion of CaSO₄·2H₂O to CaSO₄·0.5H₂O via the formation of Ca₃(PO₄)₂ and produces CaSO₄·0.5H₂O whiskers with thinner diameters and shorter lengths. Compared with the blank experiment without Na₂HPO₄·12H₂O, the existence of minor amounts (8.65 × 10⁻⁴–4.36 × 10⁻³ mol/L) of Na₂HPO₄·12H₂O led to a decrease in the diameter of CaSO₄·0.5H₂O whiskers from 1.0–10.0 to 0.5–2.0 μm and lengths from 70–300 to 50–200 μm.     

Experimental investigation on thermal properties of silver nanofluids

This paper reports on an experimental investigation of the thermal properties behavior of 0.5 wt% silver nanoparticle-based nanofluids (NF) containing oleic acid (OA) and potassium oleate surfactant (OAK⁺) with concentrations of 0.5, 1, and 1.5 wt% respectively. The experiments were conducted from 20 °C to 80 °C. It was shown that the NF with 1 wt% OAK⁺ yielded the highest thermal behavior enhancement of about 28% at 80 °C compared to deionized water. The thermal performance had higher than the base fluid/nanofluids at approximately 80%. Moreover, the NF containing OAK⁺ showed higher thermal conductivity and dynamics of specific heat capacity than deionized water in all of the experimental conditions in this study. The rheological experiment showed that viscosity of NF was significantly dependant on temperature. As shear rate increased, the shear stress of the NF increased; however, the viscosity of the nanofluids decreased first and then stabilized. It was further found that NF containing OAK⁺ at a range of operating temperatures produced Newtonian behavior.     

Li2SiO3 fast microwave-assisted hydrothermal synthesis and evaluation of its water vapor and CO2 absorption properties

A series of lithium metasilicate (Li₂SiO₃) powder materials has been successfully synthesized by the microwave-assisted hydrothermal route using lithium hydroxide and tetraethyl-orthosilicate-derived sol precursors. Ceramic powders were obtained under hydrothermal conditions of autogenous pressure in the presence of a nonionic surfactant. The production of pure and well-crystallized Li₂SiO₃ using very short reaction times at low temperatures was shown by X-ray diffraction, scanning electron microscopy, and N₂ adsorption-desorption analyses. Synthesized Li₂SiO₃ particles were nanocrystalline and exhibited different morphologies and specific surface areas depending on the synthesis conditions. Additionally, the capability of selected Li₂SiO₃ samples to absorb H₂O and CO₂ was evaluated via thermogravimetric analyses by varying the temperature, carrier gas, and water vapor concentration. Li₂SiO₃ particles exhibited interesting textural and morphological characteristics that make them suitable for use as a CO₂ absorbent and which suggest that they also have the potential to be used in other applications.     

Synthesis and surface modification of nanophosphorous-based flame retardant agent by continuous flow hydrothermal synthesis

Nanoparticles can provide flame retardance to hosting polymers and act as nano fire extinguishers. Hydroxyapatite (Ca₅(OH)(PO₄)₃) (HA) is not hygroscopic, and is thermally stable up to 800 °C, with 18.5 wt% phosphorous content. It is this high phosphorous content that can provide HA with flame retardant properties. In this paper, we report on the continuous synthesis of ultrafine HA using a hydrothermal synthesis technique. The HA surface properties were changed from hydrophilic to hydrophobic by post-synthesis surface modification. The ratio of the HA nanoparticles and an intumescent agent known as Exolit AP750 was investigated to yield a self-extinguishing multi-component epoxy nanocomposite for extended application under extreme fire conditions. The HA/AP750/epoxy nanocomposite was able to resist a flame at 1700 °C and self-extinguish after the flame had been removed. The nanocomposite showed an enhanced flammability performance in standard cone calorimetry testing and formed a compact and cohesive protective char layer with a 50% decrease in peak heat released compared with virgin epoxy. Our aim was to establish the use of HA as an effective nanofiller with phosphorous-based flame retardant properties. The surface of this nano fire extinguisher was modified effectively with different surfactants for enhanced compatibility with different polymeric matrices.     

Synthesis of powdered silver nanoparticles using hydrogen in aqueous medium

Environmentally benign one-pot protocol is used in the synthesis of silver nanoparticles (AgNPs) in powder form, involving the reduction of silver nitrate in the presence of fully hydrolyzed polyvinyl alcohol (PVA) as stabilizer by hydrogen (H₂) as reducing agent in aqueous medium. Fully hydrolyzed biodegradable PVA has extremely low cytotoxicity, making it a favorable stabilizer from green perspective. In the present methodology, essentially naked silver nanoparticles are obtained in good yield. The prepared silver nanoparticles were characterized by TEM, XRD, EDAX, UV–Vis spectroscopy and DLS histogram, and studied for its activity as a recyclable catalyst for synthesis of different enaminones.     

Preparation of calcium sulfate whiskers from FGD gypsum via hydrothermal crystallization in the H2SO4-NaCl-H2O system

Little attention has thus far been paid to the potential effect of solution composition on the hydrothermal crystallization of calcium sulfate whiskers prepared from flue-gas desulfurization(FGD) gypsum.When purified FGD gypsum was used as raw material,the morphology and phase structure of the hydrothermal products grown in pure water,H_2SO_4-H_2O,NaCl-H_2O,and H_2SO_4-NaCl-H_2O solutions as well as the solubility of purified FGD gypsum in these solutions were investigated.The results indicate that calcium sulfate whiskers grow favorably in the H_2SO_4-NaCl-H_2O system.When prepared using 10-70 g NaCl/kg gypsum-0.01 M H_2SO_4-H_2O at 130 ℃ for 60 min,the obtained calcium sulfate whiskers had diameters ranging from 3 to 5 |xm and lengths from 200 to 600 |xm,and their phase structure was calcium sulfate hemihydrate(HH).Opposing effects of sulfuric acid and sodium chloride on the solubility of the purified FGD gypsum were observed.With the co-presence of sulfuric acid and sodium chloride in the reaction solution,the concentrations of Ca~(2+) and SO_4~(2-) can be kept relatively stable,which implies that the crystallization of the hydrothermal products can be controlled by changing the concentrations of sulfuric acid and sodium chloride.     

纳米粒子在方管中传输与沉降的研究

采用有限体积法离散并应用Simple方法对方截面弯曲管道内的纳米粒子传输和沉降进行了数值计算,结果表明Reynolds数和Schmidt数是影响纳米粒子传输和沉降的重要参数。粒子较小时,弯管中轴向速度较大的区域就是粒子的高浓度区域,沉降增强因子最大值出现在外弯侧的中心位置;粒子较大时,截面浓度的梯度值降低,沉降增强因子趋于平均,此时整个截面的粒子平均沉降。弯曲作用对于粒子较大且Dean数也较大时的影响更加明显。