Anastasia Hiskia

• Research Director at National Centre of Scientific Research "Demokritos"

Selective targeting of senescent cells has been thus far considered a widespread preventive strategy, as well as a main or adjuvant therapy for age-associated diseases, fueling the research on the discovery of senotherapeutics (i.e., senolytic or senomorphic compounds). Given that until now no single senotherapeutic has been reported to exert a uni...

Although organic light-emitting diodes (OLEDs) are considered a mature technology, further enhancements in their efficiency are of paramount importance for advancing their incorporation in high-quality displays and flexible, wearable, electronic devices. In this regard, we propose an innovative approach, focusing on strategic modifications to the h...

Many water utilities are at least occasionally affected by unpleasant taste and odour (T&O) in drinking water. For decades, aesthetic water quality has been of secondary concern to water producers, with water safety being the primary focus. However, there has been a recent shift towards prioritising consumer satisfaction, encompassing not only serv...

Aim The aim of the present study was to assess the alterations in morphology, roughness, and composition of the surfaces of a conventional and a flowable composite attachment engaged with aligners, and to evaluate the release of resin monomers and their derivatives in an aqueous environment. Methods Zirconia tooth-arch frames (n = 20) and correspo...

Background The aim of the present study was to investigate qualitatively and quantitatively the elution of substances from polyester-urethane (Invisalign™) aligners and resin composite attachments (Tetric EvoFlow) in vivo. Methods Patients (n = 11) treated with the aligners and attachments (16 per patient, without other composite restorations) for...

Spirulina, a cyanobacterium widely used as a food supplement due to its high nutrient value, contains volatile organic compounds (VOCs). It is crucial to assess the presence of VOCs in commercial spirulina products, as they could influence sensory quality, various processes, and technological aspects. In this study, the volatile profiles of sevente...

In the past, the application of TiO2 slurry reactors has faced difficulties concerning the recovery and reusability of the catalyst. In response to these challenges, immobilized photocatalyst systems have been investigated, wherein the catalyst is fixed onto a solid support, frequently with reduced photocatalytic performance. In the present study,...

Harmful algal blooms events have been reported worldwide and during the last decades are occurred with increasing frequency and intensity due to the climate change and the high inputs of nutrients in freshwaters from anthropogenic activities. During blooms cyanobacteria release in water their toxic secondary metabolites, known as cyanotoxins, along...

In the present study, the photocatalytic performance of exfoliated graphitic carbon nitride (g-C3N4) catalysts, with enhanced properties and response in UV and visible light irradiation, was evaluated for the removal of selected contaminants i.e., diuron, bisphenol A and ethyl paraben. Commercial TiO2 Degussa P25 was also used as a reference photoc...

Aesthetic aspects of drinking water, such as Taste and Odor (T&O), have significant effects on consumer perceptions and acceptability. Solving unpleasant water T&O episodes in water supplies is challenging, since it requires expertise and know-how in diagnosis, evaluation of impacts and implementation of control measures. We present gaps, challenge...

Cyanobacteria produce a plethora of structurally diverse bioactive secondary metabolites, including cyanotoxins which pose a serious threat to humans and other living organisms worldwide. Currently, a wide variety of mass spectrometry-based methods for determination of microcystins (MCs), the most commonly occurring and studied class of cyanotoxins...

Aim To quantitatively assess the degree of conversion and the water-leaching targeted compound from 3D-printed aligners. Materials and methods 3D-printed aligners were made of photopolymerized resin (Tera Harz TC85A). The molecular structure and degree of conversion of the set resin were investigated by ATR-FTIR spectroscopy (n = 5). The aligners...

Toxic cyanobacteria in freshwater bodies constitute a major threat to public health and aquatic ecosystems [...]

At present, cyanobacteria and their toxins (also known as cyanotoxins) constitute a major threat for freshwater resources worldwide. Cyanotoxin occurrence in water bodies around the globe is constantly increasing, whereas emerging, less studied or completely new variants and congeners of various chemical classes of cyanotoxins, as well as their deg...

In the last decades, cyanobacterial harmful algal blooms (CyanoHABs) pose an intensifying ecological threat. Microcystis aeruginosa is a common CyanoHAB species in freshwater ecosystems, with severe toxic effects in a wide range of organisms. In the present paper we examined whether transient and short (48-hours) exposure of fish embryos to subleth...

Cyanobacteria are photosynthetic microorganisms that are able to produce a large number of secondary metabolites. In freshwaters, under favorable conditions, they can rapidly multiply, forming blooms, and can release their toxic/bioactive metabolites in water. Among them, anabaenopeptins (APs) are a less studied class of cyclic bioactive cyanopepti...

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and tot...

Lake Karaoun is the largest artificial lake in Lebanon and serves multiple purposes. Recently, intensive cyanobacterial blooms have been reported in the lake, raising safety and aesthetic concerns related to the presence of cyanotoxins and cyanobacterial taste and odor (T&O) compounds, respectively. Here, we communicate for the first time results f...

Water radiolysis can serve as a useful tool to study the degradation of organic pollutants in water. Manipulation of the radiolytic system enables the selective production of reactive species (RS) with known yields. Our aim was to explore the effects of the radiolytically produced RS on commonly occuring water taste and odor compounds (T&O), 2-meth...

Cyanotoxins (CTs) produced by cyanobacteria in surface freshwater are a major threat for public health and aquatic ecosystems. Cyanobacteria can also produce a wide variety of other understudied bioactive metabolites such as oligopeptides microginins (MGs), aeruginosins (AERs), aeruginosamides (AEGs) and anabaenopeptins (APs). This study reports on...

Biological and advanced chemical treatment of cyanotoxins and other cyanobacteria-related contaminants such as taste and odor compounds, results in the formation of myriad transformation products (TPs) prior to their mineralization to simpler compounds such as H2O and CO2. This chapter gives an overview of the TPs formed for the major groups of cya...

The production of β-Ν-methylamino-L-alanine (BMAA) in cyanobacteria is triggered by nitrogen-starvation conditions and its biological role, albeit unknown, is associated with nitrogen assimilation. In the present study, the effect of BMAA (773 μg L⁻¹) on nitrogen metabolism and physiology of the non-diazotrophic cyanobacterium and non-BMAA producer...

Advanced oxidation processes (AOPs) have become significant and attractive technologies for the removal of cyanotoxins and cyanobacteria in contaminated waters due to their outstanding performance in this field. Details are presented in this chapter regarding the introduction of each AOP and important studies and applications of different AOPs for...

About this book Provides a comprehensive overview of key methods for treating water tainted by cyanobacteria and cyanotoxins Toxigenic cyanobacteria are one of the main health risks associated with water resources. Consequently, the analysis, control, and removal of cyanobacteria and cyanotoxins from water supplies is a high priority research ar...

Microginins are the less common class of bioactive linear cyanobacterial peptides. Recently, an investigation for their presence in cyanobacteria from Greek freshwaters and strain cultures was carried out. The present dataset is related to the research article “New microginins from cyanobacteria of Greek freshwaters” [1]. Cyanobacterial biomass fro...

The present study was launched as a continuation of global efforts to tackle problems associated with two important aesthetic characteristics, taste and odor (T&O), of drinking water. The UV-A/Chlorine process, a promising advanced oxidation process (AOP), was evaluated for the first time for the removal of 2-isopropyl-3-methoxy pyrazine (IPMP), a...

Cyanobacteria can form extensive blooms in water with concurrent production and release of a large number of chemically diverse and bioactive metabolites, including hazardous toxins. Significant number of the metabolites belongs to non-ribosomal peptides, with unique residues, unusual structures and great potential for biotechnological application....

Cyanobacteria are a diverse group of photosynthetic Gram-negative bacteria that produce an array of secondary compounds with selective bioactivity against a broad spectrum of organisms and cell lines. In this study, 29 strains isolated from freshwaters in Greece were classified using a polyphasic approach and assigned to Chroococcales, Synechococca...

Cyanobacterial diversity associated with sponges remains underestimated, though it is of great scientific interest in order to understand the ecology and evolutionary history of the symbiotic relationships between the two groups. Of the filamentous cyanobacteria, the genus Leptolyngbya is the most frequently found in association with sponges as wel...

Increased rates of reactive oxygen/nitrogen species (ROS/RNS) are involved in almost all cancer types, associated with tumor development and progression, causing damage to biomolecules such as proteins, nucleic acids and membrane lipids, in different biological compartments. We used a human tumor xenograft mouse model to evaluate for the first time...

Abstract Toxic cyanobacteria occur in Greek surface water bodies. However, studies on the occurrence of cyanotoxins (CTs) are often limited to mainly microcystins (MCs), with use of screening methods, such as ELISA, that are not conclusive of the chemical structure of the CT variants and can be subject to false positive results. A multi-lake survey...

The investigation of conditions allowing multi-electron reduction and reoxidation of polyoxometalate (POM) films onto solid substrates is considered an issue of critical importance for their successful incorporation in electronic devices, different types of sensors and catalytic systems. In the present paper, the rich multi-electron redox chemistry...

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent probl...

The cyanobacterium Cylindrospermopsis raciborskii represents a challenge for researchers and it is extensively studied for its toxicity and invasive behaviour, which is presumably enhanced by global warming. Biogeography studies indicate a tropical origin for this species, with Greece considered as the expansion route of C. raciborskii in Europe. T...

Cyanobacteria are photosynthetic microorganisms distributed globally in aquatic and terrestrial environments. They are also industrially cultivated to be used as dietary supplements, as they have a high nutritional value; however, they are also known to produce a wide range of toxic secondary metabolites, called cyanotoxins. BMAA (β-methylamino-l-a...

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to thei...

Insight into how environmental change determines the production and distribution ofcyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus onhepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g.,anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their p...

This paper presents the first report of cyanobacteria and cyanotoxins from the South Caucasus region, in particular from Lake Yerevan (Armenia). Microcystis, Dolichospermum, and Planktothrix were the key genera identified during the growing season. A trend of a remarkable increase in cyanobacterial densities was observed from 2012 to 2013 exhibitin...

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent probl...

Advanced Oxidation Processes (AOPs) that rely on the efficient generation of reactive radical species increasingly attract greater interest with respect to their application to water remediation from a wide variety of organic micropollutants concerning human health or the environment.

Water radiolysis is known as an Advanced Oxidation Process (AOP) for treatment of organic pollutants but it can also serve as a useful tool to study the effects of highly reactive species that are commonly present in AOPs. Such studies are carried out in simpler homogeneous systems that can be manipulated with use of scavengers to selectively produ...

Until now, only two ISO standards are available for assessing the photocatalytic activity of surfaces with regards to water purification. In this frame, a new European standard for testing water purification performance of photocatalytic materials is under development by the European Committee for Standardization, Technical Committee 386 “Photocata...

p>This review aims to summarise the outcomes of some recent European research concerning toxic cyanobacteria and cyanotoxins, with an emphasis on developments within the framework of the CYANOCOST Action (COST Action ES1105, Cyanobacterial Blooms and Toxins in Water Resources: Occurrence, Impacts and Management). State of the art research and manag...

p>Lake Karla (Central Greece) is a unique example - at European scale - of a shallow lake ecosystem that was dried in the 1960s and in 2009 started to be restored. The lake is listed in the network of the Greek protected areas as it is considered a vital aquatic ecosystem, in terms of biodiversity. It has, however, already been adversely affected b...

5',8-Cyclo-2'-deoxyadenosine (cdA) and 5',8-cyclo-2'-deoxyguanosine (cdG) in their two diastereomeric forms, 5'S and 5'R, are tandem lesions produced by the attack of hydroxyl radicals to the purine moieties of DNA. Their formation has been found to challenge the cells' repair machinery, initiating the nucleotide excision repair (NER) for restoring...

Method validation is an important requirement in the practice of chemical analysis and laboratory accreditation according to ISO 17025. Validation of analytical methods includes the confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use are fulfilled. In subsequent parts of the c...

A wide variety of analytical methods are available for the assessment of microcystins, including physicochemical and biological methods. Most methods measure toxin concentrations, rather than toxicity. A simple, easy-to-use biological method that measures toxicity is the protein phosphatase inhibition assay. This chapter summarises the current know...

This SOP specifies a method for the solid phase extraction (SPE) of microcystins (MCs) and nodularin (NOD) from drinking water or filtered water samples. The extracts produced by this method are suitable for subsequent analysis by LC-MS/MS or HPLC-PDA. This extraction method is suitable for the determination of MCs and NOD that are in solution (exo...

This SOP specifies a method for the solid-phase extraction (SPE) of cylindrospermopsin (CYN) from drinking water or filtered water (e.g. filtered surface water) samples. The extracts produced by this method are suitable for subsequent analysis by LC-MS/MS. This extraction method is suitable for the determination of cylindrospermopsin that is dissol...

This SOP outlines a basic protocol for in-house validation of methods for cyanotoxins analysis in environmental samples. This protocol can be used for laboratory accreditation according to ISO 17025. The protocol assesses repeatability, reproducibility, trueness, limit of quantitation, limit of detection, and range of measurement and can be used wi...

Since the development of atmospheric pressure ionisation (API), especially the electrospray ionisation (ESI) interface, liquid chromatography–mass spectrometry (LC-MS) has become a routine analytical tool. The strength of LC-MS lies in its ability to selectively determine trace analytes in very complex sample matrices. The fast scanning speeds of m...

The protein phosphatase inhibition assay (PPIA) can be used for a quantitative screening of microcystins and nodularin. Commercially kits for PPIA are available in microplate format, using p-nitrophenyl phosphate as substrate and photometric measurement of its conversion to p-nitrophenol. This SOP gives additional guidance for the application of co...

This SOP specifies a method for the determination of cylindrospermopsin (CYN) in filtered water (e.g. filtered surface water) and drinking water samples by LC-MS/MS. The method can be applied after solid-phase extraction (SPE) of CYN according to SOP 15. The combination of these SOPs is proved to be suitable for determinations at the low ng L–1 lev...

This chapter presents a case study of a toxic Planktothrix rubescens bloom in the Serbian reservoir Vrutci used as the water supply for the city of Užice. Chemical cyanotoxin analyses were supplemented by Artemia salina bioassays, a questionnaire directed to the inhabitants of Užice, and epidemiological work. The overall aim of the studies was to a...

Cyanobacteria produce a wide range of taste and odour compounds (T&O) that are generally not toxic but degrade the aesthetic quality of water sources and supplies. Cyanobacteria T&O consist of several chemical groups with the terpenoids geosmin and 2-methylisoborneol being the most widespread in water resources. Detection and identification of wate...

Various enzyme-linked immunosorbent assay (ELISA) kits are commercially available for screening of microcystins (MCs) and nodularins (NODs). The kits are based on competitive-photometric assays using various protocols and antibodies in microplate format. As performance of ELISA kits varies widely with sample matrix and protocol used, it is recommen...

Geosmin (GSM) and 2-methylisoborneol (2-MIB) are the two most common cyanobacterial metabolites that give unfavourable taste and odour to water. Their odour thresholds in water are extremely low, in the range of a few ng/l. This SOP describes a method for the detection and quantitative determination of GSM and 2-MIB at low ng/L concentrations in wa...

This SOP specifies a method for the determination of cyclic peptide cyanotoxins, microcystins, and nodularin by LC-MS/MS in filtered water and drinking water samples. The method can be applied after solid-phase extraction of the target compounds. Method validation under repeatability and reproducibility conditions has shown that this method meets v...

This SOP specifies a method for the determination of anatoxin-a in filtered water (e.g. filtered surface water) and drinking water samples by LC-MS/MS. The method avoids interferences from the presence of phenylalanine that has the same mass fragmentation pattern with anatoxin-a. This is achieved through chromatographic separation of anatoxin-a and...

High-performance liquid chromatography (HPLC) has been extensively used for the separation of cyanotoxins and their detection with either photodiode array (PDA) or mass spectrometry. The separation of microcystins and nodularins is usually performed by reverse-phase sorbents in acidic mobile phases. Acetonitrile as the organic phase provides superi...

This SOP specifies a method for the solid-phase extraction of anatoxin-a from drinking water or filtered water samples. The extracts produced by this method are suitable for subsequent analysis by LC-MS/MS. This extraction method is suitable for the determination of anatoxin-a that is dissolved in water (not inside cells or bound to other material)...

During the past 20 years, the elucidation of biosynthetic pathways of cyanotoxins and the development of analytical chemistry tools have shed light into cyanotoxin production in aquatic ecosystems. Analyses of cyanobacteria have shown that along with MCs other cyanotoxins as well as other bioactive compounds may be produced by a single strain. Ther...

Planktonic Nostocales cyanobacteria represent a challenge for microbiological research because of the wide range of cyanotoxins they synthesize and their invasive behavior, which is presumably enhanced by global warming [1]. In this study, eight strains representing six Nostocalean taxa (Anabaenopsis elenkinii, Cylindrospermopsis raciborskii, Sphae...

During the growth and decay of cyanobacteria blooms a wide range of volatile metabolites and degradation-breakdown products are released in water including terpenoids, aldehydes, ketones, alcohols, pyrazines, amines and sulfurous compounds [1]. Some of those compounds have strong characteristic odors even at very low concentrations (e.g. in the ng/...

The occurrence and ecotoxicology of cyanobacteria are well documented in freshwater habitats, however studies in marine environments have not been carried out to the same extent. To date, toxicity has been reported in marine cyanobacteria belonging to the genera Oscillatoria, Synechococcus, Synechocystis, and there are scarce records for Leptolyngb...

Cyanobacterial and algal toxins comprise a large group of harmful metabolites, belonging to different chemical classes, with a variety of chemical structures, physicochemical properties and toxic activities. In this study, a fast, simple and sensitive analytical method was developed for the simultaneous determination of multi-class cyanobacterial a...

The cyanobacterium Aphanizomenon favaloroi was identified for the first time in Europe in the Mediterranean brackish Lake Vistonis during July–August 2014. It formed a dense bloom (from 16 × 10⁶ to 81 × 10⁶ trichomes L–1), causing a brown colouration of the lake water. When A. favaloroi formed 100% of the total phytoplankton biomass (44 mg L–1), sa...

Exposure to β-N-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer’s disease and Parkinson’s disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compa...

Exposure to β-N-methylamino-L-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compa...

This chapter discusses thoroughly the outcomes of the TiO2 photocatalytic degradation of organic contaminants of emerging concern, including manmade (insecticides, organochlorinated compounds, and antibiotics) and naturally occurring compounds (cyanotoxins and taste and odor compounds). Specifically, information is provided on the degradation of va...

Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, however the reaction pathways and degradation processes of organic pollutants are not yet clearly defined. The presence of cyanobacteria cause water quality problems since several genera can produce potent cyanotoxins, harmful to human health. In additi...

Hepatotoxic microcystins (MCs) are the most frequently detected group of cyanobacterial toxins. This study investigated the degradation of common MC variants in water, MC-LR, MC-RR, MC-YR and MC-LA, by UV-254 nm-based processes, UV only, UV/H2O2, UV/S2O8(2-) and UV/HSO5(-). Limited direct photolysis of MCs was observed, while the addition of an oxi...

Research on the development of new TiO2 based photocatalysts has been receiving increased attention due to the ability of TiO2 to degrade a great variety of organic compounds upon UV-A irradiation. In order to evaluate the photocatalytic performance of the new synthesized materials, it is essential to follow specific procedures during the photocata...

This chapter presents findings of different studies on the prevention and elimination of cyanobacterial blooms in source water resources as well as the removal of cyanotoxins during water treatment with physical processes. Initially, treatments that can be applied at the source water and can limit the formation of Cyano-HABs, such as aeration and t...

Cyanobacteria are considered a rising environmental problem, since under favorable conditions, they can form extensive algal blooms and produce a wide range of cyanotoxins, which pose a significant risk to aquatic habitats and human health. Anatoxin-a (ANA) and Cylindrospermopsin (CYN), are two important cyanotoxins, often found in water bodies wor...

Geosmin (GSM) and 2-methylisoborneol (MIB) are produced by several species of cyanobacteria and actinomycetes. These compounds can taint water and fish causing undesirable taste and odours. Studies have shown that GSM/MIB are resistant in standard water treatments. Polyoxometalates (POM) are efficient photocatalysts in the degradation and mineraliz...

Cyanobacteria (blue-green algae) are considered an important water quality problem, since several genera can produce toxins, called cyanotoxins that are harmful to human health. Cylindrospermopsin (CYN) is an alkaloid-like potent cyanotoxin that has been reported in water reservoirs and lakes worldwide. In this paper the removal of CYN from water b...

Cyanobacteria are often grouped into primary and secondary metabolites, wherein the former are essential for growth, development and reproduction of the organism while the latter are indirectly involved in the organisms' survival but their absence does not result in immediate death of the organism. These secondary metabolites are the main focus of...

Microcystin-LR (MC-LR) is the most common and toxic variant of the group of microcystins (MCs) produced during the formation of harmful cyanobacterial blooms. Geosmin (GSM) and 2-methylisoborneol (MIB) may also be produced during cyanobacterial blooms and can taint water causing undesirable taste and odor. The photocatalytic degradation of MC-LR, G...

Cylindrospermopsin is an important cyanobacterial toxin found in water bodies worldwide. The ever-increasing and global occurrence of massive and prolonged blooms of cylindrospermopsin-producing cyanobacteria poses a potential threat to both human and ecosystem health. Its toxicity is associated with metabolic activation and may involve mechanisms...

A method for the determination of the hepatotoxic cyanotoxins microcystins (MCs, i.e. MC-LR, MC-RR, MC-YR, MC-LA) and nodularin (NOD) in water was developed using liquid chromatography with electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS) after solid phase extraction (SPE). New patterns of fragmentation of MC-LA were obser...

Cyanobacteria blooms pose an environmental hazard because of the release of water soluble toxic compounds, called cyanotoxins. Microcystins (MCs), hepatotoxic cyclic peptide toxins, are the most widespread cyanotoxins with microcystin-LR (MC-LR) the most common and toxic variant. Health effects of MCs have resulted in the need of using efficient tr...