Ultrafast Laser-Ablated Nanoparticles and Nanostructures for Surface-Enhanced Raman Scattering-Based Sensing Applications
June 16th, 2023
Ultrafast laser ablation in liquid is a precise and versatile technique for synthesizing nanomaterials (nanoparticles [NPs] and nanostructures [NSs]) in liquid/air environments. The laser-ablated nanomaterials can be functionalized with Raman-active molecules to enhance the Raman signal of analytes placed on or near the NSs/NPs.
Laser ablation and liquids technique focuses on synthesizing nanoparticles and nanostructures by ablating a target material in liquid or gas environment, forming ecofriendly nanoparticles without any surfactants. This research scope involves refining the laser parameters, analyzing nanoparticle properties, exploring synthesis mechanisms, and discovering applications in various fields such as catalysis, sensing, electronics, energy storage, and biomedical imaging. Recent developments in laser ablation for nanomaterial fabrication involve tailoring the nanoparticle sizes, shapes, and composition, scalable production methods, hybrid nanomaterial synthesis, and surface functionalization.
These advances offer improved stability, extended shelf life, high scalability that is up to few grams per hour, and commercially viable colloidal nanoparticles and surface nanostructures production for diverse applications. In recent times, various other improvisations such as ultrafast vessel beam and vortex beam ablation processes have been implemented to generate exotic nanostructures as well as nanoparticles, with tuneable shapes, sizes, and topographies. Technologies advancing nanoparticle synthesis via ultrafast laser ablation include molecular dynamic simulations for understanding the formation of these nanoparticles, precise control for tailoring nanoparticle size, shape, and composition in C-2 TEM characterization and real time monitoring techniques.
The experimental challenges involved are automation techniques through improved instrumentation and technology, addressing the initial establishment cost of the laser ablation technique itself, ensuring proper sample preparation, controlling the contamination, and announcing data analysis and interpretation for increased accuracy and reliability of the results. In our laboratory, we have investigated diverse materials such as gold, silver, zinc, titanium, copper, silicon, gallium arsenide, germanium, rafoxanide, aphnea, and various bi-metallic, tri-metallic, and plasma mononucleotides. Laser ablation experiments were conducted in different environments using various focusing conditions for precise material processing and nanoparticle synthesis.
To begin, choose the target material and surrounding liquid. Perform ultrasonic cleaning of the target surface using acetone for 15 minutes to remove organic materials such as oils, greases, and waxes. Subject the surface to ultrasonic cleaning with ethanol for another 15 minutes to remove polar contaminants like salts and sugars, then clean the surface with deionized water, using ultrasonic cleaning for 15 minutes to remove any residual solvents or contaminants from the sample's surface.
Measure the weight of the sample before ablation, then perform a laser ablation experiment on the sample. Measure the weight of the sample again after the ablation experiment. Estimate the amount of material removed during the experiment by comparing the weight of the sample before and after ablation.
Next, adjust the input laser power to approximately 150 milliwatts for picosecond laser ablation of the silver target. Combine a polarizer and a half wave plate to adjust the laser pulse energy. Focus the laser beam onto the sample using a focusing lens to ablate the material's surface.
Manually adjust the laser's focus on the sample using a translation stage in the Z direction while observing the bright plasma produced and the cracking sound emanating. Next, use focusing optics for focusing the laser beam onto the sample, depending on achieving different ablation depths and improving control over nanoparticles and nano structures synthesis. Position the sample on the XY stage connected to an ESP controller, ensuring it moves perpendicular to the laser propagation direction.
Adjust the scan speed and laser processing area to optimize the number of laser pulses interacting with the sample. During the laser ablation process, perform laser patterning while scanning the sample to achieve the desired dimensions and prevent single point ablation. Next, for laser ablation in liquid, conduct a laser ablation experiment.
Monitor laser power and other settings to maintain consistency. Continuously observe the target material during the experiment, ensuring the laser beam stays focused on the desired area. The absorption spectra of silver colloidal nanoparticles revealed that surface plasmin resonance peaks were observed at 420, 394, and 403 nanometers for different laser wavelengths.
The normalized absorbance spectra of silver/gold alloy nanoparticles with different compositions revealed a surface plasmin resonance peak shift from 410 to 519 nanometers, as the gold percentage increased from zero to 100.
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Overview
Ultrafast laser ablation in liquid is a precise technique for synthesizing nanoparticles and nanostructures in various environments. This method allows for the creation of eco-friendly nanomaterials without surfactants and enables functionalization with Raman-active molecules to enhance signal detection.
Key Study Components
Area of Science
- Nanomaterials synthesis
- Laser ablation techniques
- Nanoparticle applications
Background
- Focus on synthesizing nanoparticles and nanostructures.
- Research includes refining laser parameters and analyzing properties.
- Applications span catalysis, sensing, electronics, and biomedical imaging.
- Recent advancements include scalable production and hybrid nanomaterial synthesis.
Purpose of Study
- To explore the synthesis mechanisms of nanoparticles.
- To improve stability and scalability of nanomaterials.
- To develop commercially viable production methods for diverse applications.
Methods Used
- Ultrafast laser ablation in liquid environments.
- Molecular dynamic simulations for nanoparticle formation.
- Real-time monitoring techniques for synthesis control.
- C-2 TEM characterization for tailoring nanoparticle properties.
Main Results
- Improved control over nanoparticle size, shape, and composition.
- Production rates scalable to grams per hour.
- Development of exotic nanostructures with tunable properties.
- Enhanced stability and shelf life of colloidal nanoparticles.
Conclusions
- Ultrafast laser ablation is a versatile method for nanomaterial synthesis.
- Advancements in techniques lead to better control and scalability.
- Potential applications in various fields highlight the method's significance.
Frequently Asked Questions
Executive Industry Relevance
Ultrafast laser ablation enables the rapid, surfactant-free synthesis of nanoparticles and nanostructures with tunable properties, directly supporting advanced SERS-based sensing platforms. This capability enhances early-stage detection of hazardous analytes, providing predictive confidence for biopharma discovery and safety workflows. The method's scalability and reproducibility position it as a reusable asset for portfolio-wide analytical innovation.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Facilitates interrogation of molecular interactions via SERS-active substrates for analyte detection.
- Enables biological de-risking by supporting trace-level identification of diverse molecules.
- Improves predictive confidence in target engagement through sensitive, quantitative readouts.
Screening & Assay Development
- Provides standardized nanostructured substrates for reproducible SERS-based assays.
- Supports assay scalability and platform reuse through high-throughput nanoparticle synthesis.
- Enables reliable compound evaluation by enhancing Raman signal detection sensitivity.
Translational & Preclinical Research
- Aligns with translational biomarker strategies by enabling detection of biomolecules at trace levels.
- Supports continuity from discovery to preclinical validation via robust analytical outputs.
- Reduces mechanistic ambiguity in analyte identification for risk-adjusted advancement.
Pipeline & Workflow Integration
Ultrafast laser-ablated nanomaterials integrate into the discovery-to-preclinical continuum as enabling tools for SERS-based detection, supporting both hypothesis testing and downstream assay development.
- Discovery Biology: Enhances hypothesis testing and pathway clarification through sensitive analyte detection.
- Screening: Delivers reproducible, quantitative SERS outputs for assay readiness.
- Analytics: Provides spectral measurements and statistical outputs for condition comparison.
- Translational Research: Supports biomarker alignment and preclinical continuity where trace detection is required.
- Enterprise Reuse: Offers a scalable, standardized platform for repeated analytical deployment.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in analyte detection.
- Operational Value: Enables standardization, reproducibility, and high-throughput scalability in nanoparticle synthesis.
- Strategic Value: Improves go/no-go decisions and capital efficiency by supporting robust analytical workflows.
- Portfolio Impact: Facilitates risk-adjusted prioritization and advancement across discovery and safety portfolios.
Implementation Considerations
- Requires expertise in laser ablation instrumentation and nanoparticle characterization.
- Demands access to Raman spectrometry and real-time monitoring infrastructure.
- Necessitates cross-team standardization for substrate preparation and data analysis.
- Adaptation across different target materials and analyte classes may require protocol optimization.
- Initial establishment costs and contamination control are practical considerations for deployment.
