TY - CONF A1 - Mezera, Marek T1 - Bacterial adhesion on femtosecond laser-induced periodic surface structures N2 - Biofilm formation in industrial or medical settings is usually unwanted and leads to serious health problems and high costs. Inhibition of initial bacterial adhesion prevents biofilm formation and is, therefore, a major mechanism of antimicrobial action of surfaces. Surface topography largely influences the interaction between bacteria and surfaces which makes topography an ideal base for antifouling strategies and eco-friendly alternatives to chemical surface modifications. Femtosecond laser-processing was used to fabricate sub-micrometric surface structures on silicon and stainless steel for the development of antifouling topographies on technical materials. T2 - Future Tech Week 2020 CY - Online meeting DA - 21.09.2020 KW - Laser-induced periodic surface structures (LIPSS) KW - Bacterial adhesion KW - Biofilm growth KW - Structural color KW - Femtosecond laser processing PY - 2020 UR - http://futuretechweek.fetfx.eu/wp-content/uploads/gravity_forms/2-5432af7ecff9e0243d7383ab3f931ed3/2020/09/BioCombs4Nanofibers_Poster-for-Future_Tech_Week_2020_08-09-2020_with_Reprint-permission_for_upload.pdf AN - OPUS4-51233 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Anja T1 - Bacterial adhesion on ultrashort laser processed surfaces N2 - Bacterial biofilms are multicellular communities adhering to surfaces and embedded in a self-produced extracellular matrix. Due to physiological adaptations and the protective biofilm matrix itself, biofilm cells show enhanced resistance towards antimicrobial treatment. In medical and industrial settings, biofilms on e.g. for implants or for surfaces in food-processing industry can be a fertile source of bacterial pathogens and are repeatedly associated with persisting, nosocomial and foodborne infections. As extensive usage of antibiotics and biocides can lead to the emergence of resistances, various strategies are currently developed, tested and improved to realize anti-bacterial surface properties through surface functionalization steps avoiding antibiotics. In this study, contact-less and aseptic large-area ultrashort laser scan processing is employed to generate different surface structures in the nanometer- to micrometer-scale on technical materials, i.e. titanium-alloy, steel, and polymer. The processed surfaces were characterized by optical and scanning electron microscopy and subjected to bacterial colonization studies with Escherichia coli test strains. For each material, biofilm results of the fs-laser treated surfaces are compared to that obtained on polished (non-irradiated) surfaces as a reference. Depending on the investigated surfaces, different bacterial adhesion patterns were found, suggesting an influence of geometrical size, shape and cell appendages of the bacteria and – above all – the laser-processed nanostructure of the surface itself. T2 - European Materials Research Society Spring Meeting 2021 CY - Online Meeting DA - 31.05.2021 KW - Bacterial adhesion KW - Biofilm formation KW - Ultrashort laser processing KW - Laser-induced periodic surface structures (LIPSS) PY - 2021 UR - https://www.european-mrs.com/laser-material-processing-fundamental-interactions-innovative-applications-emrs AN - OPUS4-52765 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sediqi, Salmin T1 - Multi-principal element alloy nanoparticle (MPEA-NP) electrocatalysts prepared by pulsed laser ablation for electroreduction of CO2 N2 - Multi-principal element alloy (MPEA) nanoparticle electrocatalysts have the potential to provide a cost-effective and efficient alternative to noble metal electrocatalysts. The chemically complex nature and the high configurational entropy of MPEAs offer advantages in tailoring catalytic activity, product selectivity, and improved stability under harsh reaction conditions. Cu-containing bimetallic catalyst systems have already been demonstrated to lead to a significant increase in catalytic efficiency compared to monometallic systems. Thus, this project aims at the design of Cu-containing MPEAs and nanoparticle electrocatalysts for carbon dioxide reduction reaction. In this project, base alloys were prepared by means of arc melting with subsequent homogenization treatments and processed by pulsed laser ablation in water and organic solvents into high-purity nanoparticles. The nanoparticles were characterized by means of transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). Electrochemical testing was performed both on bulk alloy samples and nanoparticle film coated glassy carbon electrodes by means of cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Nanoparticle coated electrodes have been investigated by means of atomic force microscopy (AFM) and scanning kelvin probe force microscopy (SKPFM) to assure a homogeneous distribution on the electrode surface. The presentation will summarize our initial results on the electrocatalytic activity of Cu-MPEA system for carbon dioxide reduction. T2 - OPERANDO SPM 2023 CY - Berlin DA - 15.11.2023 KW - Chemically Complex Materials KW - CCMat KW - Electrocatalysis PY - 2023 AN - OPUS4-59402 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sediqi, Salmin T1 - Multi-principal element alloy nanoparticle (MPEA-NP) electrocatalysts prepared by pulsed laser ablation for electroreduction of CO2 N2 - The motivation and overall objective of the project are to develop electrocatalysts that are free of noble metals (e.g., Pt or Au) and are instead based on medium and high entropy alloys (MEA\HEA) of transition metals for the electrochemical reduction of CO2. The MEA\HEA are multi principal element alloys (MPEAs) consisting of more than three elements with almost equal alloying proportions, forming solid solutions without intermetallic phases. In such a crystal structure, the individual elements are well mixed, and each atom has different nearest neighbours. In catalysis, especially in selectivity, it is precisely this atomic chaos that matters. Due to the large number of possible combinations of elements, these materials offer excellent conditions to tune their functional properties for specific applications. Especially, catalyst systems in which Cu is combined with another metallic component show a significant increase in catalytic efficiency compared to monometallic systems. Since the catalytic activity, selectivity, and stability of electrocatalysts strongly depend on the size and surface, systematic studies on the influence of the organic stabilizers on heterogeneous catalysis are also of interest. The focus of this project is to design Cu-based MEA\HEA electrocatalysts on the atomic level. For this purpose, base alloys will be prepared, processed into high-purity nanoparticles by pulsed laser ablation, and tested as electrocatalysts. T2 - Tag der Chemie 2023 CY - Berlin, Germany DA - 05.07.2023 KW - Chemically Complex Materials KW - CCMat KW - Electrocatalysis PY - 2023 AN - OPUS4-59403 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sediqi, Salbin T1 - Synthesis and characterization of multi-principal element alloys (MPEAs) for electrocatalysis applications N2 - The aim of this project is the development of novel, noble metal-free electrocatalysts that do not rely on critical minerals. We focus on multi-principal element alloys (MPEAs), especially combinations involving Cu, to significantly enhance the efficiency of the CO2 reduction reaction. Generally, MPEAs consist of more than three elements, forming solid solutions without intermetallic phases. The unique disordered random structure introduces synergetic effects that play a critical role in electrocatalysis, particularly in terms of selectivity. The neraly-endless combinations of elements that can be incorporated in MPEAs offer ample opportunities to tailor its functionality for various applications. This study presents the development of thin films based on NiZnCu MPEAs for the CO2 reduction reaction. The one-step electrodeposition of NiZnCu films was performed on Cu substrates in a single bath using a Hull cell under constant current or potential. The influence of pH, additives and current density or potential on the composition and microstructure of the films was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Atomic force microscopy (AFM) was used to study the topography and surface roughness of the NiZnCu films. The results indicate that the addition of ethylenediaminetetraacetic acid (EDTA) and citrate enhances the uniformity and adhesion of the thin films. Electrochemical measurements, including cyclic voltammetry, linear sweep voltammetry and impedance spectroscopy were conducted to study the electrocatalytic activity and the corrosion resistance of NiZnCu thin films. The NiZnCu gradient films deposited in the Hull cell enable high-throughput screening of the electrocatalytic activity. With this approach, multiple compositions showing high activity, selectivity and stability were identified. Further analysis with in line / at line product analysis was performed using a rotating disc electrode setup coupled to gas chromotography (GC) and high-performance liquid chromotography (HPLC). The presentation will summarize the results of our screening study with few deep-dives in selected compositions showing superior performance. T2 - eMRS 2024 Spring Meeting CY - Strasbourg, France DA - 27.05.2024 KW - CCMat KW - Energy conversion KW - Electrocatalysis PY - 2024 AN - OPUS4-62633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Dinter, Adelina-Elisa T1 - Deciphering corrosion processes of MIC organisms - single cell-ICP-ToF-MS analysis of archaea on solid steels N2 - ICP-ToF (time of flight) MS enables the analysis of the multi-element fingerprint of single cells. The single cell ICP-ToF-MS is used in the presented poster for the analysis of archaea involved in microbiologically influenced corrosion (MIC) of steel. By means of sc-ICP-ToF-MS, the possible uptake of individual elements from the respective steel is investigated - the information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts. The work combines modern methods of analytical sciences with materials. T2 - SALSA - Make & Measure 2021 CY - Online meeting DA - 16.09.2021 KW - Sc-ICP-ToF-MS KW - Single cell analysis KW - Microbiologically influenced corrosion KW - Archaea KW - Poster presentation PY - 2021 AN - OPUS4-53337 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Chemical and topographical changes upon sub-100-nm LIPSS formation on titanium alloy N2 - Laser-induced periodic surface structures (LIPSS) have gained remarkable attention as they represent a universal phenomenon that is often accompanying laser-processing. Such LIPSS enable a large variety of different surface functionalizations for applications in the fields of optics, fluidics, tribology, or medicine. Moreover, so-called “high spatial frequency LIPSS” (HSFL) provide an appealing and straightforward way for surface nanostructuring featuring spatial periods even below 100 nm – far beyond the optical diffraction limit. However, the imposed surface functionalities are usually caused by both, topographic and chemical surface alterations. For exploring these effects in detail, multi-method characterizations were performed here for HSFL on processed Ti- 6Al- 4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ~1 ps pulse duration, 1 – 400 kHz pulse repetition rate) under different laser and scan processing conditions. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), stylus profilometry (SP), and white light interference microscopy (WLIM), as well as near-surface chemical analyses by X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results allow to qualify the laser ablation depth, the geometrical HSFL characteristics and provide detailed insights into the depth extent and the nature of the ps-laser-induced near-surface oxidation. Significance for medical applications will be outlined. T2 - E-MRS Spring Meeting 2023 CY - Strasbourg, France DA - 29.05.2023 KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser processing KW - Hard X-ray photoelectron spectroscopy (HAXPES) KW - Time-offlight secondary ion mass spectrometry (ToF-SIMS) KW - Ti6Al4V alloy PY - 2023 AN - OPUS4-58531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Chemical and topographical analyses of ps-laser generated HSFL on titanium alloy N2 - Laser-induced periodic surface structures (LIPSS) enable a large variety of different surface functionalizations for applications in the fields of optics, fluidics, tribology, or medicine. Moreover, high spatial frequency LIPSS (HSFL) provide an appealing and straightforward way for the generation of surface nanostructures featuring spatial periods even below 100 nm – far beyond the optical diffraction limit. However, the imposed surface functionalities are usually caused by both, topographic and chemical surface alterations. For exploring these effects in detail, multi-method characterization was performed here for HSFL processed on Ti-6Al-4V alloy upon irradiation with near-infrared ps-laser pulses (1030 nm wavelength, ~1 ps pulse duration, 1 – 400 kHz pulse repetition rate) under different scan processing conditions. The subsequent sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), stylus profilometry (SP), as well as near-surface chemical analyses by X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES) and depth-profiling time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results allow to qualify the laser ablation depth, the geometrical HSFL characteristics and provide detailed insights into the depth extent and the nature of the ps-laser-induced near-surface oxidation arising from the laser-processing in ambient air and into the relevance of heat-accumulation effects at high pulse repetition rates. Moreover, the direct comparison of the HAXPES and XPS data reveals the role of surface-covering organic contaminants adsorbed from the ambient atmosphere without ion-sputter depth profiling. Furthermore, reduction of the oxides by sputtering can be avoided. T2 - SPIE Photonics Europe 2024 Conference, Symposium "Lasers and Photonics for Advanced Manufacturing" CY - Strasbourg, France DA - 07.04.2024 KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrafast laser processing KW - Nanostructures KW - Chemical analyses PY - 2024 UR - https://spie.org/photonics-europe/presentation/Chemical-and-topographical-analyses-of-ps-laser-generated-high-spatial/13005-69#_=_ AN - OPUS4-59853 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mezera, Marek T1 - Influence of the pulse repetition rate on the chemical and morphological properties of laser generated surface structures N2 - Inter-pulse accumulation of heat could affect the chemical and morphological properties of the laser processed material surface. Hence, the laser pulse repetition rate may restrict the processing parameters for specific laser-induced surface structures. In this study, the evolution of various types of laser-induced micro- and nanostructures at various laser fluence levels, effective number of pulses and at different pulse repetition rates (1 – 400 kHz) are studied for common metals/alloys (e.g. steel or titanium alloy) irradiated by near-infrared ultrashort laser pulses (925 fs, 1030 nm) in air environment. The processed surfaces were characterized by optical and scanning electron microscopy (OM, SEM), energy dispersive X-ray spectroscopy (EDX) as well as time of flight secondary ion mass spectrometry (TOF-SIMS). The results show that not only the surface morphology could change at different laser pulse repetition rates and comparable laser fluence levels and effective number of pulses, but also the surface chemistry is altered. Consequences for medical applications are outlined. T2 - European Materials Research Society Spring 2021 Meeting CY - Online meeting DA - 31.05.2021 KW - Laser-induced pariodic surface structures KW - LIPSS PY - 2021 AN - OPUS4-52778 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bonse, Jörn T1 - Bacterial adhesion on ultrashort pulse laser processed surfaces ― more than size matters! N2 - Bacterial biofilms are aggregates of bacterial cells, often attached to a surface and enclosed by a self-produced extracellular matrix which confers increased stress tolerance and resistance to cleaning. Biofilm formation leads to biofouling which gives rise to high costs in numerous technical settings due to biocorrosion and biodegradation. However, biofilms can also be attractive for industrial settings such as wastewater treatment systems or for soil bioremediation processes. Hence, the control of bacterial adhesion to a surface is of major concern. Surface topography strongly influences bacterial adhesion. Therefore, one promising way to achieve bacteria-guiding surfaces lies in the contactless and aseptic large-area laser processing of technical surfaces. We used short and ultrashort pulsed laser systems to generate different surface textures, mainly high-spatial-frequency and low-spatial-frequency laser-induced periodic surface structures, LIPSS (HFSL and LFSL), on Ti, Ti-alloy, steel, and polymers (PET and PE). Pristine (polished) and laser processed samples were subjected to bacterial adhesion experiments with two different Escherichia coli strains and Staphylococcus aureus as test organisms. The bacterial strains differed in their cell wall structure (grampositive vs. gramnegative strains), in size, shape, the occurrence of cell appendages, and in their biofilm forming capabilities. Adhesion patterns were analyzed microscopically and compared regarding the respective test strain and surface topography. Our results revealed that adhesion behavior strongly depends not only on the material’s topography and chemistry, but also on the specific bacterial strain, the presence of cell appendages, and ambient growth conditions. T2 - 13th International Conference on Photoexcited Processes and Applications, ICPEPA-13 CY - Lecce, Italy DA - 14.09.2025 KW - Biofilm KW - Bacterial adhesion KW - Laser-induced periodic surface structures (LIPSS) KW - Ultrashort laser pulses PY - 2025 AN - OPUS4-64166 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -