Evangelia A. Pavlatou

N. Lagopati, N. Pippa, M.-A. Gatou, N. Papadopoulou-Fermeli, V.G. Gorgoulis, M. Gazouli, E.A. Pavlatou

Applied Sciences 2023, 13, 9172

Aquatic habitats cover almost 70 % of the Earth, containing several species contributing to marine biodiversity. Marine and aquatic organisms are rich in chemical compounds that can be widely used in biomedicine (dentistry, pharmacy, cosmetology, etc.) as alternative raw biomaterials or in food supplements. Their structural characteristics make them promising candidates for tissue engineering approaches in regenerative medicine. Thus, seaweeds, marine sponges, arthropods, cnidaria, mollusks, and the biomaterials provided by them, such as alginate, vitamins, laminarin, collagen, chitin, chitosan, gelatin, hydroxyapatite, biosilica, etc., are going to be discussed focusing on the biomedical applications of these marine-originated biomaterials. The ultimate goal is to highlight the sustainability of the use of these biomaterials instead of conventional ones, mainly due to the antimicrobial, anti-inflammatory, anti-aging and anticancer effect.

doi: 10.3390/app13169172

Μ.-Α. Gatou, Ι.-Α. Vagena, Ν. Pippa, Μ. Gazouli, Ε.Α. Pavlatou, Ν. Lagopati

Crystals 2023, 13, 1236

This review study aims to present, in a condensed manner, the significance of the use of crystalline carbon-based nanomaterials in biomedical applications. Crystalline carbon-based nanomaterials, encompassing graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, and graphene quantum dots, have emerged as promising materials for the development of medical devices in various biomedical applications. These materials possess inorganic semiconducting attributes combined with organic π-π stacking features, allowing them to efficiently interact with biomolecules and present enhanced light responses. By harnessing these unique properties, carbon-based nanomaterials offer promising opportunities for future advancements in biomedicine. Recent studies have focused on the development of these nanomaterials for targeted drug delivery, cancer treatment, and biosensors. The conjugation and modification of carbon-based nanomaterials have led to significant advancements in a plethora of therapies and have addressed limitations in preclinical biomedical applications. Furthermore, the wide-ranging therapeutic advantages of carbon nanotubes have been thoroughly examined in the context of biomedical applications.

doi: 10.3390/cryst13081236

M.-A. Gatou, I.-A. Vagena, N. Lagopati, N. Pippa, M. Gazouli, E.A. Pavlatou

Nanomaterials 2023, 13, 2224

Over the last ten years, there has been a growing interest in metal–organic frameworks (MOFs), which are a unique category of porous materials that combine organic and inorganic components. MOFs have garnered significant attention due to their highly favorable characteristics, such as environmentally friendly nature, enhanced surface area and pore volume, hierarchical arrangements, and adjustable properties, as well as their versatile applications in fields such as chemical engineering, materials science, and the environmental and biomedical sectors. This article centers on examining the advancements in using MOFs for environmental remediation purposes. Additionally, it discusses the latest developments in employing MOFs as potential tools for disease diagnosis and drug delivery across various ailments, including cancer, diabetes, neurological disorders, and ocular diseases. Firstly, a concise overview of MOF evolution and the synthetic techniques employed for creating MOFs are provided, presenting their advantages and limitations. Subsequently, the challenges, potential avenues, and perspectives for future advancements in the utilization of MOFs in the respective application domains are addressed. Lastly, a comprehensive comparison of the materials presently employed in these applications is conducted.

doi: 10.3390/nano13152224 

M.-A. Gatou, E. Fiorentis, N. Lagopati, E.A. Pavlatou

Water 2023, 15, 2773

Organic pollutants found in industrial effluents contribute to significant environmental risks. Degradation of these pollutants, particularly through photocatalysis, is a promising strategy ensuring water purification and supporting wastewater treatment. Thus, photodegradation of rhodamine B and phenol under visible-light irradiation using TiO₂/SiO₂ composite nanoparticles was within the main scopes of this study. The nanocomposite was synthesized through a wet impregnation method using TiO₂ and SiO₂ nanopowders previously prepared via a facile sol–gel approach and was fully characterized. The obtained results indicated a pure anatase phase, coupled with increased crystallinity (85.22 %) and a relative smaller crystallite size (1.82 nm) in relation to pure TiO₂ and SiO₂ and an enhanced specific surface area (50 m²/g) and a reduced energy band gap (3.18 eV). Photodegradation of rhodamine B upon visible-light irradiation was studied, showing that the TiO₂/SiO₂ composite reached total (100 %) degradation within 210 min compared to pure TiO₂ and SiO₂ analogues, which achieved a ≈45 % and ≈43 % degradation rate, respectively. Similarly, the composite catalyst presented enhanced photocatalytic performance under the same irradiation conditions towards the degradation of phenol, leading to 43.19 % degradation within 210 min and verifying the composite catalyst’s selectivity towards degradation of rhodamine B dye as well as its enhanced photocatalytic efficiency towards both organic compounds compared to pure TiO₂ and SiO₂. Additionally, based on the acquired experimental results, ●O²⁻, h⁺ and e⁻ were found to be the major reactive oxygen species involved in rhodamine B’s photocatalytic degradation, while ●OH radicals were pivotal in the photodegradation of phenol under visible irradiation. Finally, after the TiO₂/SiO₂ composite catalyst was reused five times, it indicated negligible photodegradation efficiency decrease towards both organic compounds.

doi: 10.3390/w15152773

E. Galata, C.M. Veziri, G.V. Theodorakopoulos, G.E. Romanos, E.A. Pavlatou

Membranes 2023, 13, 627

The adhesion enhancement of a graphene oxide (GO) layer on porous ceramic substrates is a crucial step towards developing a high-performance membrane for many applications. In this work, we have achieved the chemical anchoring of GO layers on custom-made macroporous disks, fabricated in the lab by pressing α-Al₂O₃ powder. To this end, three different linkers, polydopamine (PDA), 3-Glycidoxypropyltrimethoxysilane (GPTMS) and (3-Aminopropyl) triethoxysilane (APTMS), were elaborated for their capacity to tightly bind the GO laminate on the ceramic membrane surface. The same procedure was replicated on cylindrical porous commercial ZrO₂ substrates because of their potentiality for applications on a large scale. The gas permeance properties of the membranes were studied using helium at 25°C as a probe molecule and further scrutinized in conjunction with water permeance results. Measurements with helium at 25°C were chosen to avoid gas adsorption and surface diffusion mechanisms. This approach allowed us to draw conclusions on the deposition morphology of the GO sheets on the ceramic support, the mode of chemical bonding with the linker and the stability of the deposited GO laminate. Specifically, considering that He permeance is mostly affected by the pore structural characteristics, an estimation was initially made of the relative change in the pore size of the developed membranes compared to the bare substrate. This was achieved by interpreting the results via the Knudsen equation, which describes the gas permeance as being analogous to the third power of the pore radius. Subsequently, the calculated relative change in the pore size was inserted into the Hagen–Poiseuille equation to predict the respective water permeance ratio of the GO membranes to the bare substrate. The reason that the experimental water permeance values may deviate from the predicted ones is related to the different surface chemistry, i.e., the hydrophilicity or hydrophobicity that the composite membranes acquire after the chemical modification. Various characterization techniques were applied to study the morphological and physicochemical properties of the materials, like FESEM, XRD, DLS and Contact Angle.

doi: 10.3390/membranes13070627

E. Fiorentis, M.-A. Gatou, N. Lagopati, E.A. Pavlatou

Biomedical Journal of Scientific and Technical Research 2023, 15 (1), 42382

Silica nanoparticles (SiNPs) are widely utilized in various industries, such as food, synthetic processes, medical diagnosis and drug delivery, owing to their adjustable particle size, extensive surface area and excellent biocompatibility. Numerous studies have explored the biomedical applications of SiNPs, including the customization of their surfaces and structures to target different types of cancers and facilitate disease diagnosis. This mini review encompasses recent research on the biomedical applications of SiNPs, incorporating fundamental discoveries and ongoing exploratory advancements of their research, and particularly their implementation in drug delivery systems for the diagnosis and treatment of various diseases within the human body, holding potential for practical developments in the future.

doi: 10.26717/BJSTR.2023.51.008057

N. Lagopati, Th.-F. Valamvanos, V. Proutsou, K. Karachalios, N. Pippa, M.-A. Gatou, I.-A. Vagena, S. Cela, E.A. Pavlatou, M. Gazouli, E. Efstathopoulos

Chemosensors 2023, 11(6), 317

Early-stage, precise disease diagnosis and treatment has been a crucial topic of scientific discussion since time immemorial. When these factors are combined with experience and scientific knowledge, they can benefit not only the patient, but also, by extension, the entire health system. The development of rapidly growing novel technologies allows for accurate diagnosis and treatment of disease. Nanomedicine can contribute to exhaled breath analysis (EBA) for disease diagnosis, providing nanomaterials and improving sensing performance and detection sensitivity. Through EBA, gas-based nano-sensors might be applied for the detection of various essential diseases, since some of their metabolic products are detectable and measurable in the exhaled breath. The design and development of innovative nanomaterial-based sensor devices for the detection of specific biomarkers in breath samples has emerged as a promising research field for the non-invasive accurate diagnosis of several diseases. EBA would be an inexpensive and widely available commercial tool that could also be used as a disease self-test kit. Thus, it could guide patients to the proper specialty, bypassing those expensive tests, resulting, hence, in earlier diagnosis, treatment, and thus a better quality of life. In this review, some of the most prevalent types of sensors used in breath-sample analysis are presented in parallel with the common diseases that might be diagnosed through EBA, highlighting the impact of incorporating new technological achievements in the clinical routine.

doi: 10.3390/chemosensors11060317

M.-E. Kassalia, N. Chorianopoulos, G.-J. Nychas, E.A. Pavlatou

Applied Sciences (2023), 13 (7), 4498

The aim of the present study was to investigate the photoinduced properties of nitrogen-doped titanium dioxide (N-TiO₂) against the Salmonella ser. Typhimurium bacterial biofilm, under visible-light irradiation. The capability of N-TiO₂ nanoparticles working as multipurpose materials with antimicrobial applications, as well as environmental ones, was therefore investigated. The sol–gel method was used to synthesize N-TiO₂ particles, which were then characterized by Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), Brunauer–Emmett–Teller (BET) analysis of surface area, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS), and transmission electron microscopy (TEM). The results showed that the particles formed were nano-sized and had the expected Ti-O bonds and the presence of elemental N. The as-produced N-TiO₂ nanoparticles (NPs) were tested for their antimicrobial activity. The antibacterial photocatalytic testing was performed under visible-light irradiation, on Salmonella Typhimurium biofilm. To form the biofilm, stainless steel (ss) coupons were incubated with three different strains of Salmonella Typhimurium bacteria for 48 h at 15°C in tryptone soy broth (TSB). After the biofilm’s formation, the coupons were placed on a horizontal, rectangular, batch, equipped with a vis-LED irradiation source reactor in the presence of N-TiO₂ NPs. After 1, 2, and 3 h of irradiation, sampling of the bacterial population was assessed. The results showed an evident inhibition of proliferation under light irradiation when the N-TiO₂ was present, compared to the non-irradiated NPs. It is noteworthy that, during the first 2 h, the TiO₂ NPs specimens tended to attract more bacteria on their surface then the control specimens, due to their higher available surface area, which worked as a shelter. There were ~6% viable (remaining) Salmonella cells after the first hour of visible-light irradiation with N-TiO₂ NPs.

doi: 10.3390/app13074498

P. Pantelis, G. Theocharous, N. Lagopati, D. Veroutis, D.-F. Thanos, G.-P. Lampoglou, N. Pippa, M.-A. Gatou, I. Tremi, A. Papaspyropoulos, E. Kyrodimos, E.A. Pavlatou, M. Gazouli, K. Evangelou, V.G. Gorgoulis

Antioxidants (2023), 12 (1), 169

The contemporary lifestyle of the last decade has undeniably caused a tremendous increase in oxidative-stress-inducing environmental sources. This phenomenon is not only connected with the rise of ROS levels in multiple tissues but is also associated with the induction of senescence in different cell types. Several signaling pathways that are associated with the reduction in ROS levels and the regulation of the cell cycle are being activated, so that the organism can battle deleterious effects. Within this context, autophagy plays a significant role. Through autophagy, cells can maintain their homeostasis, as if it were a self-degradation process, which removes the “wounded” molecules from the cells and uses their materials as a substrate for the creation of new useful cell particles. However, the role of autophagy in senescence has both a “dark” and a “bright” side. This review is an attempt to reveal the mechanistic aspects of this dual role. Nanomedicine can play a significant role, providing materials that are able to act by either preventing ROS generation or controllably inducing it, thus functioning as potential therapeutic agents regulating the activation or inhibition of autophagy.

doi: 10.3390/antiox12010169

M.-E. Kassalia, Z. Nikolaou, Ε.A. Pavlatou

Applied Sciences (2023), 13 (2), 774

The primary objective of this research is to propose and compile a specific protocol for photocatalytic measurements of modified TiO₂ particles under visible-light irradiation. Nitrogen-modified titanium dioxide (N-TiO₂) powder was synthesized by the sol–gel method and characterized by X-ray Diffraction Analysis (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Raman Spectroscopy (micro-Raman), and Ultraviolet–visible Spectroscopy (UV-Vis). Photocatalytic tests were performed on a specially designed photocatalytic batch reactor to test the ability of the powder to degrade hazardous toxic compounds. Via the Taguchi method, nine experiments (L9) were compiled to examine the factors that affect the photocatalytic activity of the nano-sized powder. The N-TiO₂ particles were characterized by the dominance of the crystalline anatase phase, exhibiting crystals in the nano-scale. The Taguchi method was designed to control four selected parameters (pollutant selection among azo dyes, amount of catalyst to pollutant, distance of the photocatalytic cell from the radiation source, and time protocol) with three levels/options each. Conclusions were drawn regarding the way each parameter affects the final degradation of the pollutant. The parameter that proved to affect the degradation of the pollutant to a greater extent was the choice of pollutant, followed by the amount of catalyst. The other two factors almost slightly affect the process, with a similar percentage. Taking into account the abovementioned results, a photocatalytic protocol for testing TiO₂ nano-powder activity under visible light irradiation is proposed by using a batch, horizontal, rectangular, vis-LED equipped reactor with reflective walls.

doi: 10.3390/app13020774

D. Manousakis, M.-A. Gatou, N. Lagopati, E.A. Pavlatou

Biomedical Journal of Scientific & Technical Research, 47 (2), 38305-38308 

Carbon quantum dots are a new class of zero-dimensional carbon nanomaterials that due to their low toxicity, high water dispersibility and fluorescent properties, have attracted a lot of attention for biomedical applications. They can be synthesized with many different methods through both bottom-up and top-down approaches. In this mini review we summarize the existing literature regarding the electrochemical exfoliation of pure graphite that produces nanostructures of diameter smaller than 10 nm. We focus on the electrolytes that are used and the voltage applied, as the main factors that contribute on the size, structure, composition and yield of the carbon quantum dots. In order to explain the findings of the literature, we briefly analyze the mechanism of the graphite exfoliation from the ions, under applied voltage. Furthermore, we report on the many advantages that the electrochemical approach has over competing methodologies, that make it an attractive method for mass production of carbon quantum dots, with the intention to be used in biomedical applications.

doi: 10.26717/BJSTR.2022.47.007479

N. Papadopoulou-Fermeli, N. Lagopati, N. Pippa, E. Sakellis, N. Boukos, V.G. Gorgoulis, M. Gazouli, E.A. Pavlatou

Pharmaceutics (2023), 15 (1), 135

The synthesis of titania-based composite materials with anticancer potential under visible-light irradiation is the aim of this study. In specific, titanium dioxide (TiO₂) nanoparticles (NPs) chemically modified with silver were embedded in a stimuli-responsive microgel (a crosslinked interpenetrating network (IP) network that was synthesized by poly (N-Isopropylacrylamide) and linear chains of polyacrylic acid sodium salt, forming composite particles. The ultimate goal of this research, and for our future plans, is to develop a drug-delivery system that uses optical fibers that could efficiently photoactivate NPs, targeting cancer cells. The produced Ag-TiO₂ NPs, the microgel and the composite materials were characterized through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), micro-Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM). Our results indicated that Ag-TiO₂ NPs were successfully embedded within the thermoresponsive microgel. Either Ag-TiO₂ NPs or the composite materials exhibited high photocatalytic degradation efficiency on the pollutant rhodamine B and significant anticancer potential under visible-light irradiation.

doi: 10.3390/pharmaceutics15010135

M.-A. Gatou, N. Lagopati, I.-A. Vagena, M. Gazouli, E.A. Pavlatou

Nanomaterials (2023), 13 (1), 122

Semiconductor photocatalysts, particularly ZnO nanoparticles, were synthesized via the precipitation method using four different precursors (zinc acetate/zinc nitrate/zinc sulfate/zinc chloride) and compared, according to their optical, structural, photocatalytic, and anticancer properties. The materials were characterized via X-ray Diffraction method (XRD), micro-Raman, Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Dynamic Light Scattering (DLS), and Field Emission Scanning Electron Microscope (FESEM) analysis. Photocatalysis was conducted under UV and visible light irradiation, using Rhodamine B as the organic pollutant. It was observed that the highest photocatalysis efficiency was obtained by the nanoparticles synthesized from the zinc acetate used as precursor material. A cell-dependent anticancer efficiency of the tested ZnO nanoparticles was also observed, that was also attributed to the different precursors and the synthesis method, revealing that the nanoparticles that were synthesized from zinc acetate were more bioactive among the four tested precursors. Overall, the data revealed that both the enhanced photocatalytic and biological activity of ZnO nanoparticles derived from zinc acetate precursor could be attributed to the reduced crystalline size, increased surface area, as well as the observed hexagonal crystalline morphology.

doi: 10.3390/nano13010122

Membranes (2022), 12 (12), 1181

Graphene oxide (GO) oligo-layered laminates were self-assembled on porous ceramic substrates via their simple dip-coating into aqueous GO dispersions. To augment the stability of the developed composite GO/ceramic membranes and control the morphology and stacking quality of the formed laminate, short-((3-glycidoxypropyl)trimethoxy silane-GLYMO, (3-aminopropyl)triethoxy silane-APTES), and long-chain (polydopamine-PDA) molecules were involved and examined as interfacial linkers. A comparative study was performed regarding the linker’s capacity to enhance the interfacial adhesion between the ceramic surface and the GO deposit and affect the orientation and assemblage characteristics of the adjacent GO nanosheets that composed the formed oligo-layered laminates. Subsequently, by post-filtrating a GO/H2O suspension through the oligo-layered laminate membranes, the respective multi-layered ones have been developed, whereas ethylenediamine (EDA) was used in the suspension as an efficient molecular linker that strongly bonds and interlocks the GO nanosheets. The definition of the best linker and approach was conducted on macroporous α-alumina disks, due to the use of inexpensive raw materials and the ability to fabricate them in the lab with high reproducibility. To validate the concept at a larger scale, while investigating the effect of the porous substrate as regards its micrometer-scale roughness and surface chemistry, specific chemical modifications that yielded membranes with the best gas permeability/selectivity performance were replicated on a commercial single-channel monolith with a ZrO2 microfiltration layer. XRD, Raman, ATR, FESEM, and XPS analyses were conducted to study the structural, physicochemical, surface, and morphological properties of the GO/ceramic composite membranes, whereas permeance results of several gases at various temperatures and trans-membrane pressures were interpreted to shed light on the pore structural features. Concerning the short-chain linkers, the obtained results ascertain that GLYMO causes denser and more uniform assembly of GO nanosheets within the oligo-layered laminate. PDA had the same beneficial effect, as it is a macromolecule. Overall, this study shows that the development of gas-separating membranes, by just dipping the linker-modified substrate into the GO suspension, is not straightforward. The application of post-filtration contributed significantly to this target and the quality of the superficially deposited, thick GO laminate depended on this of the chemically attached oligo-layered one.

doi: 10.3390/membranes12121181  

A.G. Mitsopoulou, E.A. Pavlatou

Education Sciences (2021), 11 (11), 746

The aim of this study is to investigate the predictive factors that predispose secondary school students’ interest in studying STEM (Science, Technology, Engineering, and Mathematics) fields in higher education. For this purpose, an already existing questionnaire was used and modified properly, according to the Greek educational system. The survey was attended by 301 secondary school students, who study in Piraeus, one of the largest cities in Greece. Research findings indicated that the principles of Social Cognitive Career Theory (SCCT) are well supported. It is worth mentioning that this is the first time that such a number of variables had been examined, in order to support the SCCT. In particular, very few studies exist in literature-to the best of our knowledge-investigating the effect of more than four factors influencing students’ interest towards STEM higher studies. Learning experiences, students’ exposure to STEM activities within the school environment and outside of it (OR=0.071, p=0.002), as well as their involvement with high difficulty STEM courses (OR=0.203, p=0.038), appear to be positively correlated with the development of interest towards studies in the STEM fields. In addition, students from low-income families are more likely to follow STEM studies (OR=0.198, p=0.034). On the contrary, it has been revealed that parental educational background only supports the student’s decision to continue studies after high school, without specifying the educational field in higher education (OR=0.769, p=0.703; father’s educational level, OR=0.698, p=0.552; mother’s educational level). Data revealed that outcome expectations and self-efficacy (OR=14.366, p=0.005) are positively related to the procedure of students’ interest development to pursue STEM fields in higher education, while gender seems to be a non-regulatory factor (OR=0.886, p=0.831).

doi: 10.3390/educsci11110746 

N. Papadimitropoulos, E.A. Pavlatou

Interactive Learning Environments, 29 (6)

Physical experiments on real-world systems are proposed as a means to raise learning outcomes and Arduino microcontroller is highlighted as an appropriate tool to perform them. However, experimentation on a real system may encounter various barriers. Therefore, a learning environment was developed in order to perform Arduino experiments on digital entities when the real ones are inaccessible. That was consisted of an Arduino-based pH meter from which measurements were transmitted to three different digital entities: a shoal of goldfish, an ancient Greek temple and an ancient Greek statue. In order to evaluate the learning outcomes of teaching through physical experiments on digital entities, a pre- to post-comparison was conducted on three Greek Junior High Schools. In each school, students were divided into two subgroups. The one group was taught about Acids and Bases through physical Arduino experiments by demonstration, using real instruments and substances, with a simultaneous observation of their effects on the digital entities in real-time, while the other group was taught through the same Arduino experiments by demonstration without the use of the digital entities. The results have demonstrated that students of the former group exhibited greater learning gains regarding Declarative Knowledge than those of the latter one.

doi: 10.1080/10494820.2021.1975302

M.-A. Gatou, P. Bika, Th.Stergiopoulos, P. Dallas, E.A. Pavlatou

Energies (2021), 14 (11), 3197

Covalent organic frameworks comprise a unique class of functional materials that has recently emerged as a versatile tool for energy-related, photocatalytic, environmental, and electro-chromic device applications. A plethora of structures can be designed and implemented through a careful selection of ligands and functional units. On the other hand, porous materials for heavy metal absorption are constantly on the forefront of materials science due to the significant health issues that arise from the release of the latter to aquatic environments. In this critical review, we provide insights on the correlation between the structure of functional covalent organic frameworks and their heavy metal absorption. The elements we selected were Pb, Hg, Cr, Cd, and As metal ions, as well as radioactive elements, and we focused on their removal with functional networks. Finally, we outline their advantages and disadvantages compared to other competitive systems such as ze-olites and metal organic frameworks (MOFs), we analyze the potential drawbacks for industrial scale applications, and we provide our outlook on the future of this emerging field.

doi: 10.3390/en14113197

N. Papadimitropoulos, K. Dalacosta, E.A. Pavlatou

Journal of Science Education and Technology (2021)

A study with K-9 Greek students was conducted in order to evaluate how the declarative knowledge acquisition was affected by incorporating Arduino experiments in secondary Chemistry Education. A Digital Application (DA) that blends the use of the Arduino sensors’ experiments with digital educational material, including Virtual Labs (VLs), was constructed from scratch to be used through the Interactive Board (IB) as a learning tool by three different student groups (N = 154). In the first stage of the learning process, all groups used only the digital material of the DA. In the second stage, the three groups used different learning tools of the DA. Through the IB, the first group used Arduino experiments, the second one the VLs, and the third only static visualizations. A pre- to post-test statistical analysis demonstrated that the first two groups were equivalent in regard to achievement in declarative knowledge tests and of a higher level than the third group. Therefore, it can be concluded that conducting Arduino experiments in a mixed virtual-physical environment results in equivalent learning gains in declarative knowledge as those attained by using VL experimentation through the IB.

doi: 10.1007/s10956-020-09899-5

N. Lagopati, M.-A. Gatou, A. Gogou, E.A. Pavlatou

United Journal of Nanotechnology and Pharmaceutics (2021), 1 (1), 1-7

During the last few decades, the utilization of nanotechnology is exponentially increasing in biomedical engineering applications, such as antibiotics, antimicrobial agents, and anticancer therapies. It is known that a large number of diseases caused by pathogenic microorganisms originate from the fact that these pathogens have developed resistance in commercially available drugs. Thus, the development of novel, effective, non-toxic, and low-cost therapy for better treatment of diseases is imperative. Nanoparticles based on metals and metal oxides have emerged as a promising means of therapy due to their exceptional properties. Among these nanoparticles, zinc oxide nanoparticles (ZnO NPs) have drawn significant attention owing to their eminent biomedical properties. A variety of physical as well as chemical methods is utilized for the ZnO NPs synthesis. However, many of them include the use of hazardous reagents or are energy-consuming. For this reason, green methods are proposed to synthesize ZnO NPs using biological substrates. These methods possess significant benefits, as the extracts contribute positively to the formation and improvement of the antimicrobial activity of ZnO NPs, also acting as reducing and stabilizing agents. In this review, an integrated approach of ZnO NPs bio-synthetic techniques using microorganisms, such as bacteria, fungi and algae, plants and plant extracts, is discussed, shedding light on their comparative advantages.