1. A HepG2 cell-based biosensor that uses stainless steel electrodes for hepatotoxin detectionMartin Rozman, Zala Štukovnik, Ajda Sušnik, Amirhossein Pakseresht, Matej Hočevar, Damjana Drobne, Urban Bren, 2022, original scientific article Abstract: Humans are frequently exposed to environmental hepatotoxins, which can lead to liver
failure. Biosensors may be the best candidate for the detection of hepatotoxins because of their high
sensitivity and specificity, convenience, time-saving, low cost, and extremely low detection limit. To
investigate suitability of HepG2 cells for biosensor use, different methods of adhesion on stainless
steel surfaces were investigated, with three groups of experiments performed in vitro. Cytotoxicity
assays, which include the resazurin assay, the neutral red assay (NR), and the Coomassie Brilliant Blue
(CBB) assay, were used to determine the viability of HepG2 cells exposed to various concentrations of
aflatoxin B1 (AFB1) and isoniazid (INH) in parallel. The viability of the HepG2 cells on the stainless
steel surface was quantitatively and qualitatively examined with different microscopy techniques. A
simple cell-based electrochemical biosensor was developed by evaluating the viability of the HepG2
cells on the stainless steel surface when exposed to various concentrations of AFB1 and INH by using
electrochemical impedance spectroscopy (EIS). The results showed that HepG2 cells can adhere to the
metal surface and could be used as part of the biosensor to determine simple hepatotoxic samples.
Keywords: HepG2 cell line, impedance biosensor, adhesion, hepatotoxins, stainless steel
Published in DKUM: 10.04.2025; Views: 0; Downloads: 3
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2. Recent developments in electrochemical-impedimetric biosensors for virus detectionZala Štukovnik, Urban Bren, 2022, review article Abstract: Viruses, including influenza viruses, MERS-CoV (Middle East respiratory syndrome coronavirus), SARS-CoV (severe acute respiratory syndrome coronavirus), HAV (Hepatitis A virus), HBV (Hepatitis B virus), HCV (Hepatitis C virus), HIV (human immunodeficiency virus), EBOV (Ebola virus), ZIKV (Zika virus), and most recently SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), are responsible for many diseases that result in hundreds of thousands of deaths yearly. The ongoing outbreak of the COVID-19 disease has raised a global concern and intensified research on the detection of viruses and virus-related diseases. Novel methods for the sensitive, rapid, and on-site detection of pathogens, such as the recent SARS-CoV-2, are critical for diagnosing and treating infectious diseases before they spread and affect human health worldwide. In this sense, electrochemical impedimetric biosensors could be applied for virus detection on a large scale. This review focuses on the recent developments in electrochemical-impedimetric biosensors for the detection of viruses.
Keywords: electrochemical impedance spectroscopy, impedimetric biosensor, genosensor, aptasensor, immunosensor, virus detection, SARS-CoV-2, HIV, influenza virus, hepatitis virus
Published in DKUM: 05.12.2024; Views: 0; Downloads: 54
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3. Nanomaterials and their recent applications in impedimetric biosensingZala Štukovnik, Regina Fuchs-Godec, Urban Bren, 2023, review article Abstract: Impedimetric biosensors measure changes in the electrical impedance due to a biochemical process, typically the binding of a biomolecule to a bioreceptor on the sensor surface. Nanomaterials can be employed to modify the biosensor's surface to increase the surface area available for biorecognition events, thereby improving the sensitivity and detection limits of the biosensor. Various nanomaterials, such as carbon nanotubes, carbon nanofibers, quantum dots, metal nanoparticles, and graphene oxide nanoparticles, have been investigated for impedimetric biosensors. These nanomaterials have yielded promising results in improving sensitivity, selectivity, and overall biosensor performance. Hence, they offer a wide range of possibilities for developing advanced biosensing platforms that can be employed in various fields, including healthcare, environmental monitoring, and food safety. This review focuses on the recent developments in nanoparticle-functionalized electrochemical-impedimetric biosensors.
Keywords: impedimetric biosensor, electrochemical impedance spectroscopy, nanomaterials, metal nanoparticles, carbon nanofibers, carbon nanotubes, graphene oxide, quantum dots
Published in DKUM: 12.02.2024; Views: 6175; Downloads: 35
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4. Izdelava in optimizacija elektrokemijske celice za uporabo v biosenzoriki : magistrsko deloZala Štukovnik, 2020, master's thesis Abstract: Razvili smo elektrokemijsko celico, ki služi kot modelni biosenzor, ter kot aktivno komponento vsebuje kvasovke vrste Saccharomyces cerevisiae. Preizkušali smo različne postopke sestave elektrokemijskih celic. Pri postopku sestave elektrokemijske celice smo uporabili nerjavno jeklo, površina kovinske elektrode, pa je bila po potrebi modificirana s tanko plastjo volframovega trioksida. Na delovno elektrodo smo kot biološko komponento nanašali kvasovke Saccharomyces cerevisiae. Z modelnim biosenzorjem smo nato spremljali, kako se ob spreminjanju različnih parametrov, le-ta odziva na 10 % raztopino metanola. Za detekcijo smo uporabili metodo elektrokemijske impedančne spektroskopije (EIS), s katero smo merili frekvenčno odzivnost električnega toka in s tem pridobili podatke o plasti kvasovk na površinah elektrod, kot rezultat pa smo interpretirali Bodejeve in Nyquistove diagrame. Stabilnost naprave in pripravljenih plasti smo predhodno določevali z merjenjem potenciala odprtega tokokroga (OCP). Topografijo in sestavo elektrod smo dodatno preverjali s tehniko vrstične elektronske mikroskopije (SEM) in optično mikroskopijo. Ugotovili smo, da je pri izdelavi biosenzorja izrednega pomena debelina nanosa biološke komponente, postavitev in velikost elektrod ter izbira materiala. Dokazali smo, da so preiskani elektrokemijski biosenzorji učinkoviti pri detekciji metanola v vodnih raztopinah. Razviti modelni biosenzorji so cenovno ugodni in nam služijo kot študijski primer za razvoj kompleksnejših biosenzorjev, ki kot aktivno plast uporabljajo žive celice.
Keywords: biosenzor, elektrokemija, elektronska impedančna spektroskopija (EIS), kvasovke vrste Saccharomyces cerevisiae
Published in DKUM: 13.01.2021; Views: 1280; Downloads: 219
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5. Ekstrakcija komponent iz semen navadne ajde (Fagopyrum esculentum)Zala Štukovnik, 2018, undergraduate thesis Abstract: Za izolacijo biološko aktivnih komponent uporabljamo postopek ekstrakcije. Namen je bil ugotoviti kako izbira topila in procesni pogoji vplivajo na kvaliteto oziroma na sestavo ekstrakta pridobljenega iz navadne ajde (Fagopyrum esculentum). Pri eksperimentalnem delu smo uporabili konvencionalne in superkritične metode ekstrakcije. Izvedli pa smo tudi ekstrakcijo polisaharidov. Pridobljenim ekstraktom smo določevali vsebnost prostih ogljikovih hidratov s fenol-žveplovo metodo in vsebnost proteinov z Bradfordovo metodo ter antioksidativno aktivnost ekstraktov z uporabo 2,2-difenil-1-pikrilhidrazil (DPPH*) prostega radikala. Izvedli smo tudi analize LC-MS/MS in določili vsebnost taninov.
Najvišji izkoristek smo pridobili z ekstrakcijo po Soxhletu z uporabo topil petroleter in heksan. Ugotovili smo, da v našem primeru masni izkoristek ekstrakcije ne narašča v smeri rasti polarnosti topil. Razlog je v visoki vsebnosti nepolarnih komponent v semenih navadne ajde. Na izkoristek je vplivala tudi višja temperatura pri ekstrakciji.
Najvišjo vsebnost prostih ogljikovih hidratov smo zasledili pri ekstraktu, kjer smo ekstrahirali polisaharide in pri nepredelanem materialu. Ugotovili smo tudi, da največ proteinov vsebuje ekstrakt, pridobljen s superkritično ekstrakcijo, najmanj pa sam material. Najvišji % inhibiranega DPPH sta vsebovala ekstrakta, kjer smo kot topilo uporabili metanol in metodo po Soxhletu ter ultrazvočno ekstrakcijo. Ugotovili smo, da temperatura ne vpliva bistveno na antioksidativno aktivnost. Izvedli smo analizo taninov v naših vzorcih z LC-MS/MS. Hidrolizirajoči tanini so bili prisotni samo v metanolnih in etanolnih ekstraktih. Od teh smo identificirali le elagno in galno kislino, ki smo ju tudi kvantificirali.
Zaključimo lahko, da je velik delež spojin v ajdi nepolarne narave, ter da njihova topnost narašča z naraščujočo temperaturo. Ajda je kvalitetno živilo s številnimi pozitivnimi učinki na zdravje, saj vsebuje veliko biološko aktivnih snovi, ki smo jih tudi dokazali.
Keywords: Fagopyrum esculentum, ekstrakcija rastlinskih materialov, biološka aktivnost, organska topila, superkritična ekstrakcija, hidrolizirajoči tanini
Published in DKUM: 10.09.2018; Views: 2004; Downloads: 228
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