Laser Ablation Method Research Articles

Laser-Ablative Synthesis of Silicon-Iron Composite Nanoparticles for Theranostic Applications.

The combination of photothermal and magnetic functionalities in one biocompatible nanoformulation forms an attractive basis for developing multifunctional agents for biomedical theranostics. Here, we report the fabrication of silicon-iron (Si-Fe) composite nanoparticles (NPs) for theranostic applications by using a method of femtosecond laser ablation in acetone from a mixed target combining silicon and iron. The NPs were then transferred to water for subsequent biological use. From structural analyses, it was shown that the formed Si-Fe NPs have a spherical shape and sizes ranging from 5 to 150 nm, with the presence of two characteristic maxima around 20 nm and 90 nm in the size distribution. They are mostly composed of silicon with the presence of a significant iron silicide content and iron oxide inclusions. Our studies also show that the NPs exhibit magnetic properties due to the presence of iron ions in their composition, which makes the formation of contrast in magnetic resonance imaging (MRI) possible, as it is verified by magnetic resonance relaxometry at the proton resonance frequency. In addition, the Si-Fe NPs are characterized by strong optical absorption in the window of relative transparency of bio-tissue (650-950 nm). Benefiting from such absorption, the Si-Fe NPs provide strong photoheating in their aqueous suspensions under continuous wave laser excitation at 808 nm. The NP-induced photoheating is described by a photothermal conversion efficiency of 33-42%, which is approximately 3.0-3.3 times larger than that for pure laser-synthesized Si NPs, and it is explained by the presence of iron silicide in the NP composition. Combining the strong photothermal effect and MRI functionality, the synthesized Si-Fe NPs promise a major advancement of modalities for cancer theranostics, including MRI-guided photothermal therapy and surgery.

Formation of Agshell/Aucore Bimetallic Nanoparticles by Pulsed Laser Ablation Method: Effect of Colloidal/Solution Concentration

Formation of Agshell/Aucore Bimetallic Nanoparticles by Pulsed Laser Ablation Method: Effect of Colloidal/Solution Concentration

Enhancement of catalytic reduction of 4-nitrophenol using MoO3 nanobelts incorporated SiO2 nanocomposite fabricated by nanosecond pulsed laser ablation technique

Nanocomposites of SiO2/MoO3 having respective weight ratios of 3:1, 2:2, and 1:3 were synthesized using a nanosecond pulsed laser ablation method. The prepared samples were analyzed with UV–Vis and Raman spectroscopy, XRD, SEM, EDX, and TEM. Based on the TEM analysis, the morphology and the structure of the nanocomposites varied with the change in the ratio of MoO3, and the sample containing the highest amount of MoO3 shows a compact morphology and a higher number of nanoparticles. The band gap energy of the nanocomposites increases with an increase in MoO3 load. The nanocomposites were used in the catalytic reduction of 4-nitrophenol (4-NP) in the presence of NaBH4. The reduction time of 4-NP decreases as the amount of MoO3 increases in the nanocomposite. The rate constants were estimated at 0.0878, 0.2319, and 0.1726 min−1 for SiO2/MoO3 (3:1, 2:2, and 1:3) catalysts respectively. The results demonstrate the good catalytic performance of the prepared materials by enabling fast reduction of 4-NP.

Thermal performance of copper-distilled water nanofluid in a wavy channel

This paper carried out an experimental study to synthesize and characterize copper water based nanofluid. To do so nanoparticles were fabricated by using one-step pulsed Nd: YAG laser ablation method under ambient conditions. Copper substrate was ablated for the duration of 25 min to ensure enough volume fraction of nanoparticles inside the host fluid. Energy dispersive spectroscopy (EDS) and scanning electron microscopy were done. The morphology of the nanoparticles seems to be homogeneous. The size distribution analysis resulted in the average size of 100 nm. Also, UV–Vis spectroscopy analysis was done for four months to investigate the stability of the synthesized nanofluid. It is observed that the nanofluid is not enough stable for more than one month. On the other hand, numerical simulations were done employing Ansys Fluent software to study thermal behavior of copper nanofluid in a corrugated channel. It is observed that higher volume fraction of nanoparticles leads to the higher heat transfer rate. Also, in this study, hydrophobic wavy wall with a constant temperature was considered as a hydrodynamical approach to enhance the heat transfer rate. It is concluded that hydrophobicity contributes to the increment of Nusselt number up to 45 percent in laminar flow. Meanwhile, Discrete phase method, which attribute to the Eulerian Lagrangian approach, was simulated. Outcomes indicated that DPM method can be trusted by less than 2% error in laminar flow.

Photodetection Properties of CdS/Si Heterojunction Prepared by Pulsed Laser Ablation in DMSO Solution for Optoelectronic Application.

The high-quality n-type CdS on a p-type Si (111) photodetector device was prepared for the first time by a one-pot method based on an ns laser ablation method in a liquid medium. Cadmium target was ablated in DMSO solution, containing sulfur precursor, and stirred, assisting in 1D-growth, to create the sulfide structure as CdS nano-ropes form, followed by depositing on the Si-substrate by spin coating. The morphological, structural, and optical characteristics of the CdS structure were examined using X-ray diffraction, transmission, and scanning electron microscopy, photoluminescence, and UV-VIS spectroscopy. From X-ray diffraction analysis, the growing CdS spheres have a good crystal nature, with a high purity and desired c-axis orientation along the (002) plane, and the crystallinity was around 30 nm. According to optical characterization, high transparency was found in the visible-near-infrared areas of the electromagnetic spectrum, and the CdS spheres have a direct optical energy band gap of 3.2 eV. After that, the CdS/Si hetero-structured device was found to be improved remarkably after adding CdS. It showed that the forward current is constantly linear, while the dark current is around 4.5 µA. Up to a bias voltage of 4 V, there was no breakdown, and the reverse current of the heterojunctions somewhat increased with reverse bias voltage, while the photocurrent reached up to 580 and 690 µA for using 15 and 30 W/cm2 light power, respectively. Additionally, the ideal factors for CdS/Si heterojunction were 3.1 and 3.3 for 15 and 30 W/cm2 light power, respectively. These results exhibited high performance compared to the same heterojunction produced by other techniques. In addition, this opens the route for obtaining more enhancements of these values based on the changing use of sulfide structures in the heterojunction formation.

Pilot Study of Cytoprotective Mechanisms of Selenium Nanorods (SeNrs) under Ischemia-like Conditions on Cortical Astrocytes.

The cytoprotective properties of the trace element selenium, its nanoparticles, and selenium nanocomplexes with active compounds are shown using a number of models. To date, some molecular mechanisms of the protective effect of spherical selenium nanoparticles under the action of ischemia/reoxygenation on brain cells have been studied. Among other things, the dependence of the effectiveness of the neuroprotective properties of nanoselenium on its diameter, pathways, and efficiency of penetration into astrocytes was established. In general, most research in the field of nanomedicine is focused on the preparation and study of spherical nanoparticles of various origins due to the ease of their preparation; in addition, spherical nanoparticles have a large specific surface area. However, obtaining and studying the mechanisms of action of nanoparticles of a new form are of great interest since nanorods, having all the positive properties of spherical nanoparticles, will also have a number of advantages. Using the laser ablation method, we managed to obtain and characterize selenium nanorods (SeNrs) with a length of 1 μm and a diameter of 100 nm. Using fluorescence microscopy and inhibitory analysis, we were able to show that selenium nanorods cause the generation of Ca2+ signals in cortical astrocytes in an acute experiment through the mobilization of Ca2+ ions from the thapsigargin-sensitive pool of the endoplasmic reticulum. Chronic use of SeNrs leads to a change in the expression pattern of genes encoding proteins that regulate cell fate and protect astrocytes from ischemia-like conditions and reoxygenation through the inhibition of a global increase in the concentration of cytosolic calcium ([Ca2+]i). An important component of the cytoprotective effect of SeNrs during ischemia/reoxygenation is the induction of reactive A2-type astrogliosis in astrocytes, leading to an increase in both baseline and ischemia/reoxygenation-induced phosphoinositide 3-kinase (PI3K) activity and suppression of necrosis and apoptosis. The key components of this cytoprotective action of SeNrs are the actin-dependent process of endocytosis of nanoparticles into cells and activation of the Ca2+ signaling system of astrocytes.

Boron Nanoparticle-Enhanced Proton Therapy for Cancer Treatment.

Proton therapy is one of the promising radiotherapy modalities for the treatment of deep-seated and unresectable tumors, and its efficiency can further be enhanced by using boron-containing substances. Here, we explore the use of elemental boron (B) nanoparticles (NPs) as sensitizers for proton therapy enhancement. Prepared by methods of pulsed laser ablation in water, the used B NPs had a mean size of 50 nm, while a subsequent functionalization of the NPs by polyethylene glycol improved their colloidal stability in buffers. Laser-synthesized B NPs were efficiently absorbed by MNNG/Hos human osteosarcoma cells and did not demonstrate any remarkable toxicity effects up to concentrations of 100 ppm, as followed from the results of the MTT and clonogenic assay tests. Then, we assessed the efficiency of B NPs as sensitizers of cancer cell death under irradiation by a 160.5 MeV proton beam. The irradiation of MNNG/Hos cells at a dose of 3 Gy in the presence of 80 and 100 ppm of B NPs led to a 2- and 2.7-fold decrease in the number of formed cell colonies compared to control samples irradiated in the absence of NPs. The obtained data unambiguously evidenced the effect of a strong proton therapy enhancement mediated by B NPs. We also found that the proton beam irradiation of B NPs leads to the generation of reactive oxygen species (ROS), which evidences a possible involvement of the non-nuclear mechanism of cancer cell death related to oxidative stress. Offering a series of advantages, including a passive targeting option and the possibility of additional theranostic functionalities based on the intrinsic properties of B NPs (e.g., photothermal therapy or neutron boron capture therapy), the proposed concept promises a major advancement in proton beam-based cancer treatment.

Pool boiling on a biphilic surface where bubbles can move horizontally on the surface

In pool boiling on a horizontal surface, the flow of vapor is mainly the departure of vapor bubbles from the boiling surface. If the surface is composed of specially laid-out areas with varied wettabilities, vapor can move on the surface and out of the boiling region. In the present work, a silicon surface with such a function is fabricated using laser ablation and silanization grafting methods, and pool boiling on the surface is experimentally studied. On the biphilic surface, the boiling region is super-hydrophilic (SHI), and two opposite sides of the SHI region each is in connection to a wedge-shaped SHO (super-hydrophobic) track. The two sides of the SHO track are bounded by HO (hydrophobic) areas. Tests with air bubbles underwater show that the SHO tracks enable the directional spontaneous movement of the air bubbles on the surface, and the driving force for the natural motion is analyzed. Boiling heat transfer on the surface is compared with a SHI surface without the SHO tracks. The biphilic surface shows noticeable enhancement of heat transfer for low heat fluxes (< ∼150W/cm2) but reduces heat transfer for high heat fluxes in nucleate boiling. In addition, the biphilic surface extends the heat flux and surface temperature ranges of nucleate boiling, showing ∼14% increase of critical heat flux. The effects on boiling heat transfer are related to the observations of vapor transport by the SHO tracks.

Anticancer Activity of Au/CNT Nanocomposite Fabricated by Nanosecond Pulsed Laser Ablation Method on Colon and Cervical Cancer.

Gold nanoparticles (AuNPs) and carbon nanotubes (CNTs) are increasingly being investigated for cancer management due to their physicochemical properties, low toxicity, and biocompatibility. This study used an eco-friendly technique (laser synthesis) to fabricate AuNP and Au/CNT nanocomposites. AuNPs, Au/CNTs, and CNTs were tested as potential cancer nanotherapeutics on colorectal carcinoma cells (HCT-116) and cervical cancer cells (HeLa) using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. In addition, the non-cancer embryonic kidney cells HEK-293 were taken as a control in the study. The cell viability assay demonstrated a significant reduction in cancer cell population post 48 h treatments of AuNPs, and Au/CNTs. The average cell viabilities of AuNPs, Au/CNTs, and CNTs for HCT-116 cells were 50.62%, 65.88%, 93.55%, and for HeLa cells, the cell viabilities were 50.88%, 66.51%, 91.73%. The cell viabilities for HEK-293 were 50.44%, 65.80%, 93.20%. Both AuNPs and Au/CNTs showed higher cell toxicity and cell death compared with CNT nanomaterials. The treatment of AuNPs and Au/CNTs showed strong inhibitory action on HCT-116 and HeLa cells. However, the treatment of CNTs did not significantly decrease HCT-116 and HeLa cells, and there was only a minor decrease. The treatment of AuNPs, and Au/CNTs, on normal HEK-293 cells also showed a significant decrease in cell viability, but the treatment of CNTs did not produce a significant decrease in the HEK-293 cells. This study shows that a simplified synthesis technique like laser synthesis for the preparation of high-purity nanomaterials has good efficacy for possible future cancer therapy with minimal toxicity.

Characteristics of copper oxide and tin oxide nanoparticles produced by using pulsed laser ablation method and their application as an antibacterial agent

The synthesis of copper oxide (CuO) and tin oxide (SnO2) nanoparticles was successfully carried out using the neodymium yttrium aluminum garnet (Nd:YAG) laser ablation method. In this study, a laser beam was focused on the surface of high-purity (99.9%) Cu and Sn plates placed into deionized water (DIW) and 0.2% carboxymethyl cellulose (CMC) liquid media, respectively, to produce colloidal CuO and SnO2 nanoparticles. CuO and SnO2 nanoparticle colloids were successfully produced with greenish and brownish colors, respectively. The colloidal nanoparticles produced in CMC media are more stable. Thus, the antibacterial test on E. coli bacteria uses CuO and SnO2 samples in CMC media. Antibacterial assessments were carried out using disc diffusion and liquid dilution methods equipped with total plate counting (TPC) techniques, with a sample variation of 26 ppm CuO, 78 ppm SnO2, and a CuO-SnO2 mixture of 5:56 ppm and 19:19 ppm samples. The results of the disc diffusion test yielded the diameter of the bacterial inhibition zone. The diameter of the inhibition zone in CuO 26 ppm, SnO2 78 ppm, and CuO-SnO2 5:56 ppm and 19:19 ppm samples, respectively, were 7.43 mm, 6.39 mm, 7.18 mm, and 6.54 mm, while the liquid dilution test equipped with TPC produced the percentage of bacterial degradation, respectively, of 98.93%, 97.60%, 98.47%, and 97.73%. The results show that all variations had the effectiveness of inhibiting and killing bacteria. From the results of various bacterial tests, colloidal CuO nanoparticles are more effective than the SnO2 nanoparticles.

Apatite laser ablation Lu[sbnd]Hf geochronology: A new tool to date mafic rocks

Mafic rocks are the most common type of igneous rocks on Earth, however, constraining the crystallization age of mafic rocks can be challenging. Apatite is a common accessory phase in mafic rocks and is amenable to dating using the U–Pb system. However, the U–Pb system in apatite has a relatively low closure temperature (∼350°-550 °C) and is therefore prone to resetting by later thermal and metasomatic events. Here, a recently developed LuHf dating method using laser ablation reaction-cell mass spectrometry is applied to apatite from mafic rocks. The LuHf system in apatite has a higher closure temperature (∼650°-750 °C) compared to U–Pb, increasing the chances of obtaining primary crystallization ages. Furthermore, the laser-ablation method allows rapid data collection compared to traditional solution-based LuHf dating techniques. Four study areas were selected to compare the LuHf vs U–Pb systematics of apatite in mafic igneous rocks: the Paleoproterozoic Sudbury Igneous Complex (Canada), the Neoproterozoic Borborema Province (NE Brazil), the Paleoproterozoic Fennoscandian Shield (Finland), the Archean Yilgarn Craton and adjacent Mesoproterozoic Albany Fraser Orogen (Western Australia). For all analyzed samples that have apatite trace element compositions typical of an undisturbed primary mafic igneous lithology, the LuHf system retains primary igneous apatite crystallization ages, whereas the U–Pb system in the same grains often records isotopic disturbance or a cooling age. In few cases, the LuHf system has also been disturbed in response to recrystallization, however, such disturbance is readily detected with trace element data. Hence, this study demonstrates the potential of laser ablation apatite LuHf dating to obtain primary crystallization ages for otherwise difficult to date mafic rocks.

Soft, Sweat‐Powered Health Status Sensing and Visualization System Enabled by Laser‐Fabrication

AbstractThin and flexible skin electronics have attracted great attention for their applications in monitoring human health status continuously and intelligently. However, the versatility of these electronics is impeded by the performance of power supply and sensor modules, and their portability is also restricted by the need for external devices to handle data processing and analysis. Here, this work presents a wearable electronics system with health status sensing and visualization system (HSSVS), where the power is supplied by sweat‐activated batteries (SABs). The reported system enables the detection of crucial human physiological information, such as the Na+ concentration and the pH level in sweat, as well as skin temperature. The electrodes of the sensors and the batteries are fabricated by the laser ablation method. The laser‐induced polyimide (PI)/gelatin‐based graphene (LIGA) based sensors show a wide linear range for the sensing markers with high sensitivity, and high selectivity. The SABs based on laser‐induced PI/gelatin based graphene anchored with manganese dioxide (LIGA@MnO2) can support the entire sensing and visualization system with ultrathin, excellent biocompatibility, and mechanical properties. Additionally, incorporating a visualization design such as color changes in LEDs enables users to easily identify variations in health status. This integrated system demonstrates promising potential in smart sensing devices for health management.

Tools to analyze the organization and formation of the germline cyst in zebrafish oogenesis.

Oocytes develop in the germline cyst, a cellular organization in which germ cells are tightly interconnected and surrounded by somatic cells. The cyst produces oocytes for follicle formation and is a hub for essential processes in meiosis and oocyte differentiation. However, the formation and organization of the cyst, and their contribution to oocyte production in vertebrates remain unclear. Here, we provide tools for three-dimensional and functional in vivo analyses of the germline cyst in the zebrafish ovary. We describe the use of serial block-face scanning electron microscopy (SBF-SEM) to resolve the three-dimensional architecture of cells and organelles in the cyst at ultrastructural resolution. We present a deep learning-based pipeline for high-throughput quantitative analysis of three-dimensional confocal datasets of cysts in vivo. We provide a method for laser ablation of cellular components for manipulating cyst cells in ovaries. These methods will facilitate the investigation of the cyst cellular organization, expand the toolkit for the study of the zebrafish ovary, and advance our understanding of female developmental reproduction. They could also be further applied to the investigation of other developmental systems.

Evolution of Carbon Nanotubes, Their Methods, And Application as Reinforcements in Polymer Nanocomposites: A Review

The demand for increased performance in structural materialshasdrawn attention to the use of fiber materials as a means of reinforcement to provide structural integrity. Carbon nanotube (CNT) reinforced polymer nanocomposites have become the go-to materials due to their superior properties. CNTs possess a strength 10-100 times higher than steel yetare lighter in weight. Additionally, CNTs have a remarkable thermal stability of up to 2800°C in a vacuum, and an electrical conductivity of 103 S/cm. It also has an electric-current-carrying capacity 1000 times higher than other materials and a thermal conductivity of around 1900 W m-1K-1, which is almost double that of diamond. This article explores the potential of Carbon Nanotubes (CNTs) to reinforce structural composite materials, improve sensing, and enhance responsiveness. It also examines its structure and classification as single and multi-walled, its synthesis,including laser ablation methods, arc discharge methods, chemical vapor deposition methods, and spray pyrolysis. Additionally, it discusses the applications,structural benefits,and challenges ofcomposite materials.

Synthesis and Characterization of Copper/Silver Core-Shell Nanoparticles Synthesized by Laser Ablation Method Using a Nanosecond Nd:YAG Laser in Acetone

Synthesis and Characterization of Copper/Silver Core-Shell Nanoparticles Synthesized by Laser Ablation Method Using a Nanosecond Nd:YAG Laser in Acetone

Synthesis of Fluorescent Carbon Dots (CDs) Using Laser Ablation Method for Bioimaging Application

Carbon Dots (CDs) were synthesized using laser ablation by focusing the laser beam on carbon (Tea) material in colloid (CH3) for 3 hours. UV-Vis spectroscopic and fluorometric characterization showed absorption of the wavelength peaks caused by the control treatment and after laser ablation and coating using Poly Ethylene Glycol (PEG400). The excitation and emission energies are formulations of CDs absorbance wavelength and fluorescence intensity. The absorbance coefficient is obtained based on the absorbance value of the cuvette thickness. The transmittance value (T) is obtained based on the absorption coefficient multiplied by 100%. CD fluorescence wavelength based on control parameters was 489 nm. After laser ablation was 496 nm, and after coating was 511 nm. CDs morphology and size characteristics are 4 nm to 10 nm based on TEM measurements. Fluorescence analysis for bioimaging applications on the luminescence intensity value of internalized blue CDs in zebrafish eye organs. The average intensity of CDs in the eye organs, gill, intestinal, dorsal, and tail injection points was 88.15 %, 91.58 %, 92.76 %, and 0.00 %.

Laser-assisted synthesis of metallic composite nanostructures in aqueous solutions

The method of pulsed laser ablation in liquids (PLAL) is applied for synthesis of composite nanostructures on the basis of TiOx and ZnO combined with noble metals like Au, Pt and Pd. The metallic plate immersed in water is laser ablated by nanosecond Nd:YAG pulsed laser irradiation. Its fundamental wavelength and the fourth harmonic are used, respectively, to produce and to modify the morphology and structure of the nano-objects. The synthesis procedure consists of two consecutive steps: laser ablation of the selected metal targets followed by unfocused laser beam irradiation of the initial colloids of nanostructures. The phase composition, structural and the shape and size morphological features were assessed by analytical method – transmission electron microscopy (TEM) in its main modes – Bright Field TEM (BF TEM), High Resolution TEM (HRTEM) and Selected Area Electron Diffraction (SAED). Formation of bimetallic polycrystalline alloys and Pt/Ti(TixOy) and Pd/Ti(TixOy) core-shell nanoparticles was founded.

Synthesis, characterization, and antimicrobial properties of copper oxide nanoparticles produced by laser ablation method in chitosan solution

Copper Oxide Nanoparticles (CuONPs) show a broad spectrum of antimicrobial activity against various species of microorganisms, including gram-positive and gram-negative fungi and bacteria, but in general gram-negative bacteria are more resistant to the effects of copper nanoparticle ions than gram-positive ones. In this work, synthesis of copper oxide nanoparticles has been carried out using laser ablation methods and the nanoparticles were applied as antibacterial agent against gram-positive bacteria Enterococcus faecalis. Experimentally, Nanoparticle synthesis was carried out using laser ablation with a power of 40 mJ. Antibacterial test with disc diffusion test using disc paper soaked in 0.1% chitosan solution (negative control), sodium hypochlorite (positive control), and copper oxide nanoparticles with a concentration of 60 ppm, 80 ppm, 100 ppm; then put into a petri dish that has been planted with the Enterococcus faecalis bacteria. Copper oxide nanoparticles were formed in chitosan as confirmed by UV-Vis, FTIR, SEM and EDX analysis. Post Hoc Tukey HSD analysis showed a significant difference in the negative control group, and the inhibition zone diameter of the treatment group was the same. The synthesis of nanoparticles using laser ablation fired at a pure copper plate succeeded in producing copper oxide nanoparticles in chitosan solvent. The firing time affects the concentration and size of the nanoparticles. More laser energy is required to produce a smaller particle size due to its antibacterial activity.

Preparation of Silver Nano-particles in Benzene Solvent by Laser Ablation Method

Preparation of Silver Nano-particles in Benzene Solvent by Laser Ablation Method

Femtosecond Laser Fabrication of Curved Plasma Channels with Low Surface Roughness and High Circularity for Multistage Laser-Wakefield Accelerators.

A multistage laser-wakefield accelerator with curved plasma channels was proposed to accelerate electrons to TeV energy levels. In this condition, the capillary is discharged to produce plasma channels. The channels will be used as waveguides to guide intense lasers to drive wakefields inside the channel. In this work, a curved plasma channel with low surface roughness and high circularity was fabricated by a femtosecond laser ablation method based on response surface methodology. The details of the fabrication and performance of the channel are introduced here. Experiments show that such a channel can be successfully used to guide lasers, and electrons with an energy of 0.7 GeV were achieved.