ICMCTF 2024 Session PP6-MoM: Microfabrication Techniques with Lasers and Plasmas

Laser bioprinting can be both additive (depositing cells) and subtractive (etching) and both have power to study the micro-physiological behavior of heterogeneous tissue constructs in vitro. The use of a UV laser in both these scenarios is shown to be very powerful and this presentation will show results over this wide range of applications. The most enriched cell types in the breast tumor microenvironment are cancer cells, cancer-associated fibroblasts, and tumor-associated macrophages. To recapitulate the cellular dynamics of the breast tumor microenvironment in vitro, the most abundant cell types need to be incorporated. Laser direct write bioprinting offers a precise, gentle, and reproducible method to print disparate cell types in user-defined geometries. Herein, we develop novel laser direct write cell printing protocols – first as a customizable generalized framework, which is then adapted to print homotypic and heterotypic cancer-stromal arrays, and human macrophages. We demonstrate the ability to fabricate in vitroheterocellular constructs for studying cell-cell signaling in healthy and diseased microenvironments, as well as the capability to print human immune cells with high fidelity to pave the way for bioprinting immunocompetent tissue models going forward. Traditional in vitro scratch assays lack standardization due to poor control over wound geometry and fail to account for cell proliferation. Here, we developed a novel scratch assay that enables precise control over wound geometry using CAD/CAM laser photoablation and takes cell proliferation into consideration using a simple reaction- diffusion based mathematical model. We demonstrated that diffusivity in precisely photoablated cell layers serves as a more accurate measure of cell motility than the rate of gap closure. Further, we biologically validated this assay using cells harvested from patients and patient-derived xenografts to gain insights into the influence of the presence stromal cells on metaplastic and non-metaplastic triple negative breast cancer metastasis.

In the realm of plasmonic detection, pivotal for applications such as food and water quality monitoring, theranostics, and virus and toxin analysis, Surface Enhanced Raman Scattering (SERS) stands out as a powerful technique. Employing vibrational spectroscopy and surface nanoengineering, SERS leverages metallic nanoparticles to enhance signals through the confinement effect of the electromagnetic field, creating intense 'hot spots' near nanoscale metal surfaces. The morphology and arrangement of plasmonic nanomaterials crucially influence the formation of hot spot networks. This presentation focuses on our recent research in the plasma-assisted fabrication of advanced nanoplasmonic surfaces, showcasing nanocarbon structures, metal-oxide nanotrees, and coupled nanogold. Utilizing various plasma setups, including low-pressure and atmospheric pressure, we demonstrate their versatility, reliability, and fast, one-step processing. These surfaces excel in detecting cancerogenic toxins at ppb levels, ultrafast recognition of trace chemicals, and even bacterial DNA detection with nanogram sample amounts. The talk underscores the significant potential of plasma-assisted nanofabrication in advancing nanoplasmonic surfaces for a broad spectrum of analytical applications.

References:

[1] Shvalya, V., Filipič, G., Zavašnik, J., Abdulhalim, I., & Cvelbar, U. (2020). Applied Physics Reviews, 7(3), 031307. [2] M. Santhosh, N., Shvalya, V., Modic, M., Hojnik, N., Zavašnik, J., Olenik, J., Košiček, M., Filipič, G., Abdulhalim, I. & Cvelbar, U. (2021). Small, 17(49), 2103677. [3] Shvalya, V., Vasudevan, A., Modic, M., Abutoama, M., Skubic, C., Nadižar, N., Zavašnik, J., Vengus, D., Zidanšek, A., Abdulhalim, I., Rozman, D. & Cvelbar, U. (2022). Nano Letters, 22 (23), 9757-9765.

This presentation aims to explore laser-textured carbon-based coatings and their improved tribological properties for different applications against various materials, including brass, titanium, aluminum and steel. The study involves a comprehensive comparative analysis with benchmark carbon coatings from the market, focusing on the performance of these coatings in diverse conditions.

Moreover, our research delves deeper into the tribolayer that forms on counterpart surfaces and employs advanced analytical techniques such as Raman spectroscopy and Scanning Electron Microscopy coupled with Energy Dispersive X-ray Analysis (SEM+EDX) to gain insights into the intricate mechanisms at play.The contribution of topographical variations and structural changes to the carbon coating will be discussed.

We will also introduce a novel model to elucidate why laser textured carbon layers exhibit superior tribological performance compared to their untextured coatings and compare as well different possible mechanism for carbon transformation depending on laser pulse length between nano and femtosecond.

At the end of the presentation, we aim to present an innovative method for producing a high-performance coating that can be used for tribological applications in the cutting tool, watchmaking, and micromechanics industries.