Applied Nanoscience最新文献

SrTiO₃ is an interesting as well as evolving material with various applications in electronics, optics, and energy storage. This work includes synthesis and investigation of the different properties of strontium titanate nanoparticles and their effect on doping with rare-earth europium. Rare-earth functionalized materials are ruling the optoelectronic industry due to their characteristic emission properties. Known for its simplicity and cost-effectiveness, the combustion method is used for the successful synthesis of SrTiO₃ nanoparticles. The structural characteristics of the synthesized samples were accurately analyzed using X-ray diffraction (XRD) and found a particle-size difference from (10–15) nm with different dopant percentages of europium. Scanning electron microscopy (SEM) was performed to detect the morphology of the sample and obtain small moong beans-like agglomeration, and Raman spectroscopy was carried out to find the different bonding formations due to its structure. Photoluminescence (PL) spectroscopy was carried out to investigate the optical properties of both pure and Eu³⁺-doped SrTiO₃, revealing significant enhancements in luminescent efficiency due to doping concentration. Furthermore, the shift in the bandgap from (3.4 eV–3.2 eV) resulting from europium doping was examined using a UV–Vis spectrometer, demonstrating a noticeable change in optical absorption properties. The CIE parameter is calculated for an excitation wavelength of 395 nm and studied its emission spectra and rare emission in pink color. This study offers valuable insights into the potential applications of Eu³⁺doped SrTiO₃ nanoparticles in various technological fields, particularly optoelectronic devices like displays and advanced materials.

Hybrid nanomaterials-based polymer nanocomposites have achieved unique properties for multiple applications. This investigation focused on the impact of the synthesis of graphene oxide (GO) or silicon oxide (SiO2) nanomaterials (NM) with the combination of SiO2@GO as hybrid nanomaterials (HNMs). Either SiO₂ or GO and SiO@GO HNMs were utilized to reinforce blended polycaprolactone (PCL) and polyethyleneimine (PEI) to fabricate new PCL–PEI/SiO₂, PCL–PEI/GO, and PCL–PEI/SiO₂@GO nanocomposites using a developed acoustic-mixing-sonications procedure. Fourier transform infrared analysis reveals substantial interfacial bonds among blended polymers, SiO_2, nanoparticles, and GO nanosheets in nanocomposites_. The X-ray diffraction confirms the semi-crystalline nature of samples. Optical and field emission electron microscopy revealed homogenous and rough surfaces turned to smother with the contribution of nanomaterials. Incorporating NM and HNMs in the matrix presented transition elections at 240 nm, significantly improving compared with the blend polymer. HNMs contributions notably reduced the energy gap of the blended PCL–PEI polymers from 3.4 to 1.92 eV and 2.97 to 0.75 eV for allowed and forbidden transitions, respectively. HNMs showed the best efficacy against Gram-negative P. aeruginosa bacteria up to 30 mm and Gram-positive (E. faecalis) up to 16 mm compared to blended polymers. Using the MTT assay, the toxic effect of (PCL–PEI/SiO₂@GO) nanocomposites against breast cancer cells was notable, growing with concentration and toxic effect on cancer cells. Combining two nanomaterials presented results instead of one nanomaterial, making nanocomposites excellent candidates for several advanced applications, including optoelectronic devices, disinfectants, and antimicrobial materials.

Single-walled carbon nanotube (SWCNT) film/Si heterojunctions were obtained by depositing SWCNT films directly on a Si substrate by the floating catalyst chemical vapor deposition. The single-walled nature of the nanotubes was proven and confirmed by Raman and infrared spectroscopy, respectively. An additional ethanol post-growth treatment improved the properties of the heterojunctions by increasing densification of SWCNTs and decreasing their sheet resistance. Peaks positions of radial breathing mode obtained from the Raman mapping analysis demonstrated a random chirality (varying between armchair and zigzag) of tube structures and their very narrow diameter distribution, centered at ≈ 1.06 nm. This latter result was also confirmed by infrared spectroscopy. Properties of SWCNT/Si heterojunctions, such as ideality factor, Schottky barrier height, series resistance, SWCNT film work function and density of interface states are presented. To obtain the last two parameters by a self-consistent method, the intermediate nanolayer of silicon oxide between the SWCNT film and Si is considered. Impact of interface states and the native silicon oxide at the SWCNT/Si interface on the properties of heterojunctions is also discussed. Finally, such basic optoelectronic figures of merit as the responsivity, detectivity, and external quantum efficiency in the visible spectral range were determined and found to be comparable to the best reported for other SWCNT-based photodetectors.

Silver nanoparticles (AgNPs) have demonstrated exceptional antimicrobial activity, effectively targeting bacterial, fungal, and viral pathogens. This broad-spectrum antimicrobial efficacy makes AgNPs a valuable co-treatment alongside antibiotics, potentially mitigating the growing issue of antimicrobial resistance. Beyond their antimicrobial properties, AgNPs exhibit significant anticancer activity, employing mechanisms such as apoptosis induction and the inhibition of tumor growth and metastasis to selectively target cancer cells. Furthermore, AgNPs exhibit antioxidant potential of scavenging free radicals and reducing oxidative stress within biological systems. While AgNPs are non-toxic to humans at low concentrations, their toxicity is influenced by many factors besides concentration such as size, shape and surface charge. These multifaceted properties of AgNPs underscore the their potential in medical and therapeutic applications, such as wound dressings, catheters, medical devices, health supplement drink as well as targeted drug delivery. This study provides an overview of the characteristics of AgNPs, their diverse bioactivities, and the evidence supporting their mechanisms for effectively inhibiting bacterial growth, viral replication, cancer proliferation, and metastasis. Additionally, updated information on the toxicity, biosafety, and recent medical applications of AgNPs is discussed.

In recent years, concern about the rise of super-resistant bacteria and the environmental pollution associated with the inappropriate use of antibiotics and the waste generated during their production has grown significantly. In response to this problem, innovative solutions have been proposed, such as the use of silver nanoparticles (AgNP), recognized for their potent antimicrobial properties against a wide range of organisms, including pathogenic bacteria. This study presents an innovative and environmentally friendly approach to the synthesis of silver nanoparticles using sonotrode, where Cannabis sativa extract acts as a reducing agent, replacing sodium borohydride (NaBH₄), a commonly used but highly polluting and carcinogenic chemical reagent. The research explored the use of different concentrations of C. sativa in the green synthesis of AgNP, evaluating their physicochemical properties and antimicrobial efficacy. To confirm the concentration, chemical composition and structural features of the nanoparticles, techniques such as atomic absorption spectroscopy (AAS), dispersion X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were employed. Scanning electron microscopy (SEM) analysis revealed details about the morphology and average size of the silver nanoparticles. Finally, the antibacterial efficacy of the nanoparticles was evaluated by the agar dilution method, underlining the potential of this innovative approach in the fight against resistant bacteria and environmental pollution. The results obtained show that the 0.5% Bio-AgNPs samples produced 53% nanoparticles, while the 2% Bio-AgNPs produced 87%. EDX analysis confirmed the presence of silver (Ag), while FTIR spectra indicated the presence of phenols, flavonoids, amino groups, alkanes, and alkenes. Ag–Ag metal bond vibrations were observed in Raman spectroscopy, and SEM analysis revealed the formation of predominantly spherical nanoparticles with sizes less than 50 nm. Furthermore, bacteriological assays demonstrated that 50, 25, and 12.5 ppm concentrations of C-AgNPs and Bio-AgNPs showed significant inhibition, highlighting that 2% C. sativa provided the best antimicrobial property. The observed biocompatibility, successful reduction of silver nitrate, and remarkable antibacterial efficacy of the synthesized nanoparticles underline the great potential of green synthesis strategies in nanoparticle production. These findings suggest that nanoparticles synthesized using this method are not only effective, but also compatible with an environmentally sustainable approach.

This study presents a method for synthesizing superparamagnetic nanoparticles through the co-precipitation method, with a coating of tetrahydroxy-1,4-quinone (THQ). The diameter of the magnetite nanoparticles (MNPs) covered with THQ varied depending on the recovery method applied. When collected through magnetic decantation, they exhibited an average diameter of 15 ± 3 nm, while centrifugation of the supernatant further reduced the diameter to 12 ± 3 nm. In contrast, the uncoated MNPs had an average diameter of 17 ± 5 nm. The smaller MNPs coated with THQ displayed very low magnetic hysteresis and demonstrated superparamagnetic behavior, indicated by a blocking temperature of less than 300 K. Characterization of both the coated and uncoated MNPs encompassed structural, morphological, size, and magnetic property analyses using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM), respectively. Fourier-transform infrared spectroscopy (FT-IR) and UV–Vis spectroscopy were employed to investigate the chemical interaction between THQ and the MNPs. In addition, cyclic voltammetry was used to compare the electrochemical changes of THQ, MNPs, and MNPs coated with THQ.

This study focuses on the facile combustion synthesis of highly luminescent Y₂O₃:Sm³⁺, Gd³⁺ nanophosphors, bringing down the thermal budget to a minimum of 500 K. When Sm³⁺ ions are doped in the Y₂O₃ cubic crystal system of bandgap 5.6 eV and studied under a down-conversion excitation of 260 nm, the emission spectra offered an intense vermilion color at 608 nm due to the ⁴G_5/2 → ⁶H_7/2 transition within the Sm³⁺ ions. The Y₂O₃:2wt%Sm³⁺ matrix is co-doped with 3wt%Gd³⁺, highlighting 100% pure vermilion emission 4.21 times higher than doped samples, which is a perfect choice for domestic lightening owing to better eye compatibility. Further, post-annealing is performed to improve the structural parameters and luminescence properties, creating sufficient alterations in the crystal lattice. It is professed that Y₂O₃:Sm³⁺, Gd³⁺ nanophosphors can be effectively used in optoelectronic devices, owing to their enhanced crystallinity and photoluminescence properties resulting from the Gd³⁺ → Sm³⁺ energy transfer efficiency of 75.15%.

Ammonia gas detection has garnered widespread attention in various fields, including food, environmental industries, and medical diagnostics. In this article, we present the synthesis of graphene-based tin oxide (graphene–SnO₂) hybrid nanostructures using the hydrothermal method. Pristine tin oxide nanostructures and a series of graphene-based tin oxide hybrids containing 5 wt.%, 10 wt. %, 15 wt. %, and 20 wt. % graphene concentrations were fabricated to investigate their response as ammonia gas sensors. The X-ray diffraction and high-resolution transmission electron microscopy analysis revealed the tetragonal rutile crystal structure of both pristine SnO₂ and graphene–SnO₂ hybrid structures. The morphology of the synthesized structures was examined using scanning electron microscopy. Fourier transform infrared spectroscopy was employed to validate the functional groups present in the hybrid structures, while the band gap of the graphene–SnO₂ nanohybrid structures was determined using diffuse reflectance spectroscopy. X-ray photoelectron spectroscopy was utilized to investigate the chemical composition, electronic state, and bonding of the materials. Four probe current–voltage (I–V) measurements were conducted to investigate conductivity and ammonia-sensing behavior. Upon exposure to ammonia gas fumes, the pristine SnO₂ exhibited changes in current and resistance, ranging from 0.063 mA to 3.75 mA and 15.87 kΩ to 266.67 Ω, respectively. Similarly, the ammonia sensing behavior of hybrid structures containing 20 wt. % graphene showed changes in current and resistance, ranging from 5.42 mA to 37.8 mA and 0.18 kΩ to 26.45 Ω, respectively. These findings suggest that graphene–SnO₂ hybrid structures exhibit excellent conductivity when exposed to NH₃ gas, unlike their ammonia-absence counterparts.

The present study demonstrates the creation of silver nanoparticles (Ag NPs) in an environmentally benign manner from Cymbopogon citratus leaves extracts by employing microwave-assisted synthesis at a low power of 400 W for a short period of 180 s. The produced Ag NPs are thoroughly characterized using methods like X-ray diffraction (XRD), UV–visible spectroscopy, scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS). These Ag NPs form clusters and have unique plate-like shapes with average particle size of ~ 165 nm. To evaluate their antibacterial activity, the produced Ag NPs are tested against both gram-positive bacteria (S. aureus) and gram-negative bacteria (E. Coli, S. typhi, and Pseudomonas) at varied concentrations (1–5 mg/L). The results show strong antibacterial activity, against both gram-positive bacteria (S. aureus) and gram-negative bacteria (E. Coli, S. typhi, and Pseudomonas); and show the largest zone of inhibition diameters at 23 mm (~ 3 mg/L) and 26 mm (~ 5 mg/L) for S. aureus and Pseudomonas, respectively. The ecological potential of Cymbopogon citratus extracts as sources for the environmentally friendly synthesis of Ag NPs is highlighted in this work and the produced Ag NPs are a viable option for antibacterial treatments against pathogenic microbes.