ALLAN BERECZKI
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Artigo IPEN-doc 30047 Direct nanoplastics detection below the diffraction limit using micro Raman2023 - BERECZKI, ALLAN; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; WETTER, NIKLAUSRaman spectra of polystyrene nanoparticles of 50 nm diameter were directly measured using micro-Raman spectroscopy. Data analysis demonstrated that particles as small as 20 nm could be directly measured with this simple and robust technique.Artigo IPEN-doc 30037 Sub-10 nm nanoparticle detection using multi-technique-based micro-raman spectroscopy2023 - BERECZKI, ALLAN; DIPOLD, JESSICA; FREITAS, ANDERSON Z.; WETTER, NIKLAUS U.Microplastic pollution is a growing public concern as these particles are ubiquitous in various environments and can fragment into smaller nanoplastics. Another environmental concern arises from widely used engineered nanoparticles. Despite the increasing abundance of these nanosized pollutants and the possibility of interactions with organisms at the sub cellular level, with many risks still being unknown, there are only a few publications on this topic due to the lack of reliable techniques for nanoparticle characterization. We propose a multi-technique approach for the characterization of nanoparticles down to the 10 nm level using standard micro-Raman spectroscopy combined with standard atomic force microscopy. We successfully obtained single-particle spectra from 25 nm sized polystyrene and 9 nm sized TiO2 nanoparticles with corresponding mass limits of detection of 8.6 ag (attogram) and 1.6 ag, respectively, thus demonstrating the possibility of achieving an unambiguous Raman signal from a single, small nanoparticle with a resolution comparable to more complex and time-consuming technologies such as Tip-Enhanced Raman Spectroscopy and Photo-Induced Force MicroscopyArtigo IPEN-doc 29353 Raman Spectroscopy of irradiated and non-irradiated plastics2022 - DIPOLD, JESSICA; BERECZKI, ALLAN; PINHEIRO, GUSTAVO; VASCONCELOS, KAMILLA; FREITAS, ANDERSON Z. de; WETTER, NIKLAUS U.Understanding radiation damage to plastic is of great interest for possible construction applications. Two different plastics were gamma irradiated and their property changes were studied with micro-Raman spectroscopy, showing promising results in increasing its toughness.Resumo IPEN-doc 29320 Micro-Raman spectroscopy for identification of microplastics in the São Vicente estuarine2022 - BERECZKI, ALLAN; PASCOAL, DIEGO R.C.; DIPOLD, JESSICA; GIMILIANI, GIOVANA T.; PARRA, DUCLERC F.; FREITAS, ANDERSON Z.; WETTER, NIKLAUSMicroplastics (MPs) are a concern regarding our environment due to the risks posed by the interactions of the large amounts of anthropogenic MPs dumped in the environment with biological systems. MPs have been vastly found in the environment and are transferred to the food chain with MPs being detected in foods, beverages and even in human blood and breastmilk. Understanding the behavior and characteristics of MPs is critical to assessing potential health risks (human and environmental) related to MPs and taking steps to prevent them from entering the ecosystem. Micro Raman spectroscopy is a powerful tool for measuring and characterizing MPs particles, being considered the gold standard because it allows identification of both the polymer matrix and possible pigments and contaminants. Furthermore it offers the possibility of characterizing both the chemical structure as well as the morphological features of the MPs. We utilized a Raman system to characterize MPs from the environment. Results from a standard MP sample were successfully measured and identified to reference spectra and even small portions of the sample as small as a few μm are suitable for obtaining a high quality spectrum for identification of the material (Fig1). Samples collected from at the São Vicente estuarine are being studied and by means of comparison with the Willey database it was possible to identify MP, additives and contaminants, thus demonstrating the power of the technique.Resumo IPEN-doc 29319 From micro to nano Raman2022 - WETTER, NIKLAUS; FREITAS, ANDERSON Z.; BERECZKI, ALLAN; PASCOAL, DIEGO R.C.; DIPOLD, JESSICA; PARRA, DUCLERC; ROSSI, WAGNER; CABRAL, FERNANDA V.; RIBEIRO, MARTHA S.The environmental accumulation of nanoplastics formed by material of anthropic origin has raised doubts about their safety, especially to the human body. While microplastics are accidentally consumed, nanoplastics (NPs) are even more concerning as they are much more likely to be absorbed by human body cells. It is known that plastics smaller than 200 nm can penetrate cell membranes and cross the blood-brain barrier. Studies have shown that polystyrene (PS) NPs from the environment carry a high load of toxins capable of compromising human brain cells. Very little is still known about what effects, cytotoxic or not, these plastics have on different organs. Understanding the property-function relationship of nanoparticles in various fields of application involves determining their physicochemical properties, which is still a formidable challenge to date. Our project focuses on the development of a methodology for the detection of micro- and NPs using micro-Raman, TERS (Tip Enhanced Raman Spectroscopy), collinear Raman and AFM, nuclear techniques, as well as a methodology for in vitro evaluation of the toxic effects of these materials through biochemical assays of cytotoxicity and genotoxicity. The project contemplates the determination of the adsorption capacity of metallic ions by NPs and the absorption of micro- and nanoplastics in cell cultures with radioactive tracers, the determination of microplastics in tissues from necropsies of marine animals and gamma spectroscopy of the cellular incorporation of NPs labeled with radioactive isotopes. In figure 1 we show examples of (a) the detection of microplastics from the Santos basin and comparison to Raman reference database (KnowItAll®), (b) detection of NPs in mouse fibroblast cells and (c) detection of very small particles (50 nm) which can be achieved by co-localized techniques of AFM + Raman using special, narrow (50 m), femtosecond laser written gratings on quartz.Artigo IPEN-doc 27334 Polydispersed Nd3+:YVO4+SiO2 powders for highly efficient random lasers2020 - DIPOLD, JESSICA; SILVA, DANILO A.A. da; BERECZKI, ALLAN; JIMENEZ-VILLAR, E.; WETTER, NIKLAUS U.Random lasers are cheap and easy to fabricate, having several different applications such as early cancer detection, encryption and Speckle-free imaging. However, few fabricated random lasers present high efficiency, which limits their possible applications. In a recent work, our group achieved a record efficiency by developing random lasers that use compacted, polydispersed yttrium vanadate doped with neodymium (Nd3+:YVO4 ) powders to create separate regions for gain and light diffusion. Large particles are responsible for the light diffusion, while the small particles that occupy the spaces between them create gain pockets, absorbing the pumped light. In this work, this strategy is refined by using passive particles (SiO2) for light diffusion, restricting the laser active particles to the gain pockets. The first attempt with this strategy used 30% of Nd3+:YVO4 small powders and 70% of large SiO2 particles. Without any further optimization, the result achieved is already 40% of the highest obtained efficiency in the previously studied Nd3+:YVO4 polydisperse sample, showing a promising result to further improve this new strategy and reach even larger efficiencies with less laser active material.