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TLS Detection in Liquid Chromatography, Flow Injection Analysis and Microfluidic Systems for Food Quality Control and Biomedical Diagnostics
Mladen Franko, 2023, invited lecture at foreign university

Abstract: The basics of thermal lens spectrometry (TLS) and TLS microscopy (TLM) will be explained considering in particular the dependence of the thermal lens signal on the excitation power, thermo-optical properties of the sample, as well as sample flow and photostability of the analyte, with particular focus on the TLS enhancement factor, sensitivity and sample throughput of TLS and TLM measurements. Examples of applications will include most notable achievements of TLS and TLM measurements in liquid chromatography (detection of bilirubin and biliverdin in blood plasma, bilirubin in vascular endothelial cells), flow injection analysis (organophosphate insecticides and allergens in foodstuffs) and microfluidics (high throughput determination of Cr(VI), microcystin, HPV virus antibodies, and biomarkers of acute kidney injury). Before the concluding remarks, recent progress in multi-pass mode-mismatched TLS instrumentation and applications of incoherent light sources will be presented s part of the future outlook for TLS and TLM techniques.
Keywords: Spektrometrija TLS, TLM, chromatography, microfluidics, FIA
Published in RUNG: 14.11.2023; Views: 382; Downloads: 3
.pdf Full text (21,62 MB)

Effects of Photodegradation in TLS Measurements: Troubleshooting and Applications in Photochemistry and Photocatalysis
Mladen Franko, 2023, published scientific conference contribution abstract (invited lecture)

Abstract: Most analytical applications of thermal lens spectrometry (TLS) and related theoretical models consider absorbance of the sample constant during a single excitation by the pump laser beam. For photolabile analytes intensive excitation light can cause photodegradation, which significantly affects the results of TLS measurements. Theoretical models have been developed to account for changes in concentration and consequent changes in absorbance, caused by chemical reactions of different orders. Furthermore, abnormal TLS signal transients were observed for fast photochemical reactions on millisecond time scale, and the contributions of photodegradation as well as molecular diffusion were analyzed in detail. It has also been demonstrated that such effects can be reduced by performing TLS measurements in flowing systems such as in the case of flow injection analysis (FIA) or microfluidics. These findings were utilized to study the kinetics of chemical reactions, processes such as photostability of the soybean oil and thermal stability of biodiesel, or to improve the sensitivity of TLS detection in case of photolabile analytes. Furthermore, in combination with the concept of biomolecular recognition, FIA-TLS was exploited to study the efficiency of photocatalytic degradation of some neurotoxic substances such as organophosphate insecticides and revealed the formation of even more toxic degradation products. High sensitivity of TLS has enabled discrimination between photocatalytic and photosensitization mechanisms in photocatalytic degradation of textile dyes as well as between photodegradation and photocatalysis as will be demonstrated by the results of latest research in this field.
Keywords: Spektrometrija TLS, fotolabilnost, CrIVI), fotokataliza, fotorazgradnja
Published in RUNG: 23.10.2023; Views: 515; Downloads: 0
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Recent Progress and Applications of Thermal Lens Spectrometry and Photothermal Beam Deflection Techniques in Chemical Analysis and Materials' Characterization
Mladen Franko, 2023, invited lecture at foreign university

Abstract: Initially the theoretical background relevant to recent developments of thermal lens spectrometry (TLS) which include TLS detection in liquid chromatography and in microfluidic flow injection analysis (μFIA) and to non-contact and non-destructive characterization of composite materials by beam deflection spectrometry (BDS) is presented. The advantages and basic characteristics of the TLS and BDS techniques are illustrated by presenting applications such as the determination of free bilirubin in endothelial cells by HPLC-TLS, studies of diffusion in Taylor-type microfluidic flows by thermal lens microscopy (TLM), μFIA-TLM detection of microcystin-LR and Cr(VI) in waters, and by the dept profiling of multi-layered coatings of orthopaedic implants. In the main part of the presentation the results of joint MU-UNG research are presented with emphasis on BDS and TLS characterisation of biocomposite materials from cellulose and chitosan or keratin with added Ag nanoparticles, sporopollenin capsules or antibiotics. The focus is on BDS determination of thermal parameters including thermal diffusivity and related properties relevant for medical applications, such as porosity and surface roughness, as well as on the TLS detection of Ag and other nanoparticles applied in studies of nanoparticle leaching from biocomposites.
Keywords: Optotermična spektrometrija, TLS, BDS, kemijska analiza, karakterizacija materialov, biokompoziti
Published in RUNG: 23.10.2023; Views: 478; Downloads: 1
.pdf Full text (25,02 MB)

Recent progress and applications of thermal lens spectrometry in environmental and bio-medical sensing
Mladen Franko, 2023, published scientific conference contribution abstract (invited lecture)

Abstract: Applications of TLS in environmental and bio-medical sensing, which include determination of iron species and ammonia by TLS and comparison to their microfluidic TLM detection are presented. Advantages of microfluidic FIA-TLM in terms of sensitivity and high sample throughput for determination of microcystin, Cr(VI) and HPV virus are discussed.
Keywords: Optotermična spektrometrija TLS, biomedicinska diagnostika, monitoring okolja
Published in RUNG: 19.10.2023; Views: 540; Downloads: 4
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Frontiers in chemistry

Keywords: kemija, kemijske spojine, elektronske revije
Published in RUNG: 19.10.2023; Views: 520; Downloads: 2
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Mladen Franko, Mauro L. Baesso, G. Paltauf, V. Spagnolo, 2023, short scientific article

Abstract: This is an Editorial to the special issue of Photoacoustics, which presents a collection of selected papers from the field of photoacoustics, presented at the ICPPP21 - The 21st International Conference on Photoacoustic and Photothermal Phenomena, which took place in Bled, Slovenia, from 19 to 24 June 2022.
Keywords: photoacoustics, ICPPP21
Published in RUNG: 21.08.2023; Views: 541; Downloads: 4
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Keywords: fotoakustika
Published in RUNG: 21.08.2023; Views: 489; Downloads: 0
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