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A Simple and Rapid Method to Produce SERS Substrates Using Au Nanoparticles Prepared by Laser Ablation and DVD Template
摘要： Simple and highly sensitive SERS substrates were produced using Au nanoparticles (AuNPs) prepared by laser ablation in water and available Digital Video Discs (DVDs). We used the simple ‘‘drop-cast’’ method to deposit AuNPs on the grating pattern surface of a DVD in place of the other methods such as electrochemical deposition, electrophoretic deposition and sputtering method which require some more equipment. AuNPs were proposed to be synthesized in water by laser ablation to form a nearly circular AuNP stain of small size on a DVD surface. The protecting polycarbonate layer of a DVD was removed from the DVD surface. The bare metallic DVD surface was rinsed carefully with ethanol and distilled water. The width of tracks on a DVD surface is around 300 nm and distance between them is around 450 nm. We prepared AuNPs by pulsed laser ablation of a gold piece in distilled water. The colloidal gold nanoparticles were deposited on DVD templates. We studied to produce an effective layer of AuNPs on DVD template for SERS substrates (AuNPs/DVD). The average SERS enhancement factor of the AuNPs/DVD SERS substrates is about 106. The SERS substrates can detect SERS spectra of Malachite Green and Amoxicillin at low concentrations of around 0.1–1 ppm.
关键词： Surface enhanced Raman scattering (SERS),digital video disc (DVD),laser ablation
更新于2025-09-11 14:15:04
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Carbon coated TiO2 nanoparticles prepared by pulsed laser ablation in liquid, gaseous and supercritical CO2
摘要： We report on the synthesis of TiO2 nanoparticles using nanosecond pulse laser ablation of titanium in liquid, gaseous and supercritical CO2. The produced particles were observed to be mainly anatase-TiO2 with some rutile-TiO2. In addition, the particles were covered by a carbon layer. Raman and X-ray diffraction data suggested that the rutile content increases with CO2 pressure. The nanoparticle size decreased and size distribution became narrower with the increase in CO2 pressure and temperature, however the variation trend was different for CO2 pressure compared to temperature. Pulsed laser ablation in pressurized CO2 is demonstrated as a single step method for making anatase-TiO2/carbon nanoparticles throughout the pressure and temperature ranges 5–40 MPa and 30–50 °C, respectively.
关键词： core-shell particles,pulsed laser ablation,nanoparticle size control,supercritical fluids
更新于2025-09-11 14:15:04
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Producing graphene nanosheets by pulsed laser ablation: Effects of liquid environment
摘要： Effects of liquid environment on the characteristics of graphene nanosheets produced by the laser ablation method have been studied experimentally. The fundamental wavelength of a pulsed Nd:YAG laser at 1064 nm with 7 ns pulse width and 5 Hz repetition rate was employed to irradiate a graphite target in distilled water, liquid nitrogen, alcohol, acetone, and two concentrations of cetyltrimethylammonium bromide. Produced carbon nanostructures were diagnosed using Ultraviolet-Visible-Near Infrared and Fourier transform infrared spectroscopy, x-ray diffraction, Raman spectroscopy, transmission electron microscopy, and field emission scanning electron microscope images. Results show that different carbon nanostructures such as carbon nanoparticles and fluorine, as well as graphene nanosheets were formed in various liquid environments. The size and morphology of nanostructures strongly depends on the liquid environments and, among these liquids, water is the most capable one to produce graphene nanosheets.
关键词： Raman,carbon nanoparticles,graphene nanosheets,graphite,pulsed laser ablation
更新于2025-09-11 14:15:04
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Plasmonics and SERS activity: beyond gold and silver
摘要： The search for new plasmonic nanostructures has received significant attention recently, owing to applications in diverse fields of nanoscience and nanotechnology, and being of interest for the life sciences. Metallic nanoparticles (NP) can strongly absorb and scatter light due to their ability to support localized surface plasmon resonances (LSPR) and, therefore, play an important role in plasmonic-based techniques such as surface enhanced Raman scattering (SERS) and metal-enhanced fluorescence (MEF). Interestingly, most research in the field is still confined to Ag, Au, and less intensively Cu nanostructures, and there is an open field for the investigation of other elements such as the poor metals. In this work, we investigate plasmonic properties of different metal nanoparticles, including the post-transition metals Bi, In, Pb, and Sn; the metalloid Sb; the transition metals Ni and Co; and the metal alloy Terfenol-D. All these nanoparticles were experimentally tested for LSPR and SERS, and our results indicate SERS responses and enhancement factors comparable to the ones obtained with gold NP. The nanoparticles used in this study were produced via laser ablation synthesis in solution (LASiS) and characterized by UV-Vis optical absorption, dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and surface area electron diffraction (SAED). These laser-synthesized NP present increased LSPR in the near UV spectral region, yet also reveal multi-peak LSPR extending towards the visible, an interesting feature to be considered in the development of plasmonic sensors. For the Raman experiments, several organic and biological molecules were tested, and SERS activity was demonstrated for diverse combinations of NP and test-analytes at varying concentrations, down to single molecule detection.
关键词： plasmonics,laser ablation,nanoparticles,SERS
更新于2025-09-11 14:15:04
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Magnetic resonance image‐guided focal laser ablation in clinically localized prostate cancer: safety and efficacy
摘要： Background: To evaluate the safety and efficacy of focal laser ablation (FLA) in low-intermediate risk prostate cancer. Methods: Inclusion criteria were men aged 50–75 years, prostate-specific antigen (PSA) ≤15 ng/mL, clinical stage T1c–T2a, one or two lesions (PI-RADS ≥3) on magnetic resonance imaging (MRI), and Gleason score 6 (>3 mm) or Gleason 7 on targeted biopsy. Treatment success was defined as no clinically significant cancer in ablated areas. The study is prospective. Under MRI guidance, laser ablation was applied to the visible lesion(s). International Prostate Symptoms Score, Sexual Health Inventory in Men score and PSA levels were assessed at baseline and repeated at 1, 3, 6, 12 and 18 months. MRI was repeated at 3 and 12 months. Cancer control was assessed at 6 months using targeted and systematic biopsies. Results: FLA was performed in 49 patients. Gleason scores were 3 + 3 in 13 patients (26.5%), 3 + 4 in 29 (59.2%) and 4 + 3 in 7 (14.3%). No significant complications were noticed. International Prostate Symptoms Score measurements up to 18 months were not different from baseline (all P > 0.05). Sexual Health Inventory in Men scores dropped in the first year (all P < 0.05), but were not different from baseline levels at 18 months (P = 0.097). PSA levels dropped significantly at 3–18 months (all P < 0.05). Treatment was successful in 39 patients (79.6%). Persistent cancer in treated areas was found in 10 patients (20.4%). Conclusions: FLA is safe with no impact on urinary and sexual functions at 18 months follow-up. Oncologic control is encouraging. Larger scale studies and longer follow-up are required.
关键词： Prostate cancer,Prostate cancer treatment outcome,Focal laser ablation,Focal therapy
更新于2025-09-11 14:15:04
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A novel approach with holmium laser ablation for endoscopic management of intrahepatic biliary stricture
摘要： Background: Hepatolithiasis, featuring high incidence, severe symptoms, and common recurrence, poses a heavy disease burden. Endoscopic management provides an opportunity to cure hepatolithiasis, but fails to properly resolve biliary stricture without additional interventional techniques. An innovative approach towards endoscopic management of biliary stricture is required. Methods: Holmium laser ablation was applied to biliary strictures via endoscopic access. Patients’ demographic, operative, and follow-up data after receiving holmium laser ablation were retrospectively collected for analysis. Results: A total of 15 patients (4 males and 11 females) underwent stricture ablation by holmium laser via cholangioscopy. All the patients successfully received holmium laser ablation, indicating a technical success rate of 100%. No postoperative mortality or no major perioperative complication was observed. During the follow-up period, the recurrence-free rate was 73% at 2 years and 67% at 5 years. Conclusions: We successfully developed a novel technique of biliary stricture removal by cholangioscopic holmium laser ablation with satisfying clinical outcomes.
关键词： Hepatolithiasis,Holmium laser ablation,Biliary stricture,Cholangioscopy
更新于2025-09-11 14:15:04
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Femtosecond-laser-ablation induced transformations in the structure and surface properties of diamond-like nanocomposite films
摘要： Femtosecond laser ablation processing is applied for surface modification and micropatterning of diamond-like nanocomposite (DLN) films (a-C:H:Si:O films). Using a visible femtosecond laser (wavelength 515 nm, pulse duration 320 fs), microgroove patterns have been fabricated on the DLN films, aimed at further studies of their properties. The studies were focused on (i) structural transformations in the surface layers using Raman spectroscopy and transmission electron microscopy (TEM), (ii) wettability of laser-patterned films, and (iii) nano/microscale friction properties of laser-patterned DLN films using lateral force microscopy. Raman spectroscopy and TEM data showed characteristic features of the surface graphitization during ultrashort-pulse ablation. High resolution TEM study of the microgrooves revealed the formation of cubic SiC nanocrystals (4–8 nm size) on the laser-ablated surface. The water contact angle measurements showed anisotropic wetting behavior of the grooved surfaces (the contact angle was different in the directions parallel and perpendicular to microgrooves), depending on the groove depth (aspect ratio). Lateral force microscopy examination (with micro-sized Si tips) showed that the laser-patterned regions exhibited low friction properties compared to the original surface. The obtained results demonstrate that femtosecond laser processing is an effective technique to generate new properties of hard DLN coatings at the micro and macroscale.
关键词： Diamond-like nanocomposite films,Femtosecond laser ablation,Micropatterning,SiC nanocrystals,Graphitization,Wettability
更新于2025-09-11 14:15:04
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Sensitive and Reproducible Gold SERS Sensor Based on Interference Lithography and Electrophoretic Deposition
摘要： Surface-enhanced Raman spectroscopy (SERS) is a promising analytical tool due to its label-free detection ability and superior sensitivity, which enable the detection of single molecules. Since its sensitivity is highly dependent on localized surface plasmon resonance, various methods have been applied for electric ?eld-enhanced metal nanostructures. Despite the intensive research on practical applications of SERS, fabricating a sensitive and reproducible SERS sensor using a simple and low-cost process remains a challenge. Here, we report a simple strategy to produce a large-scale gold nanoparticle array based on laser interference lithography and the electrophoretic deposition of gold nanoparticles, generated through a pulsed laser ablation in liquid process. The fabricated gold nanoparticle array produced a sensitive, reproducible SERS signal, which allowed Rhodamine 6G to be detected at a concentration as low as 10?8 M, with an enhancement factor of 1.25 × 105. This advantageous fabrication strategy is expected to enable practical SERS applications.
关键词： laser interference lithography,electrophoretic deposition,gold nanoparticle array,surface enhanced Raman spectroscopy,pulsed laser ablation in liquid
更新于2025-09-10 09:29:36
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Size Modification of Optically Active Contamination-Free Silicon Nanoparticles with Paramagnetic Defects by Their Fast Synthesis and Dissolution
摘要： Contamination-free silicon-based nanoparticles (NPs) with several modalities are developed in this work. They are formed by non-toxic laser-assisted decomposition of silicon microgranules homogeneously dispersed in deionized water. Precise control of numerous experimental parameters allows repeatable fine tuning of nanoparticle size solving significant lacks of a direct laser ablation routine. Such a method provokes a huge amount of paramagnetic defect states of optically active silicon NPs that can serve as a contrast agent for magnetic resonance and nonlinear optical imaging. Perspectives of their bioapplication are driven by detected their fast size degradation in a NaCl-based medium.
关键词： optical properties,laser ablation,silicon nanoparticles,biomedical applications,electron paramagnetic resonance
更新于2025-09-10 09:29:36
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Preparation and Photocatalytic Activities of Black TiO <sub/>2</sub> in Vacuum and Ambient Temperature Environment
摘要： The preparation conditions are important for the structure and properties of black TiO2. In this paper, the black rutile TiO2 with a particle size of approximately 5 nm was prepared in vacuum by the infrared nano-second laser sputtering deposition method. The study results indicated that the prepared black TiO2 exhibited high light absorption from UV to near-infrared region. The lattice distortion and Ti3+ were responsible for the upward shift in the valance band, and the oxygen vacancy states were determined to be located about 0.7–1.18 eV under the conduction band, narrowing the band gap of TiO2 from 3.2 eV to 2.1 eV. Although the black TiO2 exhibited strong adsorption effects within the full spectrum and had a higher free carrier density, the presence of excess oxygen defects resulted in a higher recombination rate of the photo electron–hole pairs, which induced a poor photocatalytic performance of the black TiO2. This work facilitates the understanding of the mechanisms mechanism of black TiO2 formation via laser ablation, and emphasized the need for the controllability and quanti?cation of oxygen vacancies.
关键词： Vacuum,Laser Ablation,Oxygen Vacancy,Photocatalytic Activity,Black TiO2
更新于2025-09-04 15:30:14