Learning by teaching efficiently enhances learning outcomes in molecular biology of the cell course

To evaluate the impact of active learning approaches in a basic molecular and cell biology course for undergraduate students, we assessed the effect of learning by teaching and peer review on the learning outcomes. A literature seminar activity with peer review and feedback was organized as a compulsory activity for all students, covering about 25% of the course content. The remaining 75% of the course was delivered as classical lectures. The students collaborated in groups to present the content of a review article complemented with a research article. For each group of students, an opponent group was assigned to challenge the presenting group by questions and contribute to the evaluation of the presentation together with the teacher. Based on the feedback survey, the students reacted positively to this active learning exercise, and they strongly recommended keeping it in the future editions of the course. The students\u27 exam scores strongly indicated that the learning outcomes from the learning by teaching part of the course were consistently higher than from the classical lecture part of the course. Further optimization of the active learning part of the course is outlined based on student feedback

Technologies for biological removal and recovery of nitrogen from wastewater

Water contamination is a growing environmental issue. Several harmful effects on human health and the environment are attributed to nitrogen contamination of water sources. Consequently, many countries have strict regulations on nitrogen compound concentrations in wastewater effluents. Wastewater treatment is carried out using energy- and cost-intensive biological processes, which convert nitrogen compounds into innocuous dinitrogen gas. On the other hand, nitrogen is also an essential nutrient. Artificial fertilizers are produced by fixing dinitrogen gas from the atmosphere, in an energy-intensive chemical process. Ideally, we should be able to spend less energy and chemicals to remove nitrogen from wastewater and instead recover a fraction of it for use in fertilizers and similar applications. In this review, we present an overview of various technologies of biological nitrogen removal including nitrification, denitrification, anaerobic ammonium oxidation (anammox), as well as bioelectrochemical systems and microalgal growth for nitrogen recovery. We highlighted the nitrogen removal efficiency of these systems at different temperatures and operating conditions. The advantages, practical challenges, and potential for nitrogen recovery of different treatment methods are discussed

Interactions Between Graphene-Based Materials and Biological Surfaces: A Review of Underlying Molecular Mechanisms

Understanding the underlying molecular mechanism of how graphene materials (GMs) interact with biological surfaces is the key to develop safe and effective biomedical applications of GMs. Here, a systematic and comprehensive mechanistic perspective of interactions between pristine GMs and biological membranes is provided. To this end, first the known mechanisms of interaction between GMs and membrane components are summarized and classified, with a focus on phospholipids, cholesterol, and membrane proteins. Both experimental observations and computational simulations are included. Detailed experimental conditions and physiochemical properties of GMs are listed for each cited application. At the end of this review, current challenges and conflicts that limit biomedical applications of GMs are discussed. Based on reported mechanisms, guidelines for future studies to address the remaining challenges are proposed, specifically with respect to modulating the intrinsic properties of GMs for more efficient and safer therapeutic applications

Cold-Resistant Heterotrophic Ammonium and Nitrite-Removing Bacteria Improve Aquaculture Conditions of Rainbow Trout (Oncorhynchus mykiss)

The aim of this study was isolation and characterization of heterotrophic bacteria capable of ammonium and nitrite removal at 15 \ub0C (optimal temperature for growing rainbow trout Oncorhynchus mykiss). Environmental isolates were grown in liquid media containing ammonium or nitrite, and best strains in terms of growth and ammonium or nitrite removal were identified via 16S rRNA sequencing. Dyadobacter sp. (no. 68) and Janthinobacterium sp. (no. 100) were selected for optimal adaptation to growth at 15 \ub0C and best ammonium and nitrite removal (P < 0.05), respectively. A heterotrophic ammonium and nitrite removal (HAN) microbial complex, containing selected strains, was prepared and applied in a trout culture system. After 10 days, the effect of microbial HAN complex was investigated in terms of ammonium and nitrite removal, as well as stress and immune indices present in the plasma of cultivated trout. Compared to a standard cultivation setup, addition of the HAN complex had a clear beneficial effect on keeping the un-ionized ammonia and nitrite level below prescribed standards (P < 0.05). This resulted in reduction of stress and immune reactions of cultivated fish (P < 0.05), leading to an augmentation of final weight and survival. Application of the selected microbial complex resulted in a significant improvement of the aquaculture ecosystem

Sustained release of usnic acid from graphene coatings ensures long term antibiofilm protection

Protecting surfaces from bacterial colonization and biofilm development is an important challenge for the medical sector, particularly when it comes to biomedical devices and implants that spend longer periods in contact with the human body. A particularly difficult challenge is ensuring long-term protection, which is usually attempted by ensuring sustained release of antibacterial compounds loaded onto various coatings. Graphene have a considerable potential to reversibly interact water insoluble molecules, which makes them promising cargo systems for sustained release of such compounds. In this study, we developed graphene coatings that act as carriers capable of sustained release of usnic acid (UA), and hence enable long-term protection of surfaces against colonization by bacterial pathogens Staphylococcus aureus and Staphylococcus epidermidis. Our coatings exhibited several features that made them particularly effective for antibiofilm protection: (i) UA was successfully integrated with the graphene material, (ii) a steady release of UA was documented, (iii) steady UA release ensured strong inhibition of bacterial biofilm formation. Interestingly, even after the initial burst release of UA, the second phase of steady release was sufficient to block bacterial colonization. Based on these results, we propose that graphene coatings loaded with UA can serve as effective antibiofilm protection of biomedical surfaces

Cellular and subcellular interactions of graphene-based materials with cancerous and non-cancerous cells

Despite significant advances in early detection and personalized treatment, cancer is still among the leading causes of death globally. One of the possible anticancer approaches that is presently receiving a lot of attention is the development of nanocarriers capable of specific and efficient delivery of anticancer drugs. Graphene-based materials are promising nanocarriers in this respect, due to their high drug loading capacity and biocompatibility. In this review, we present an overview on the interactions of graphene-based materials with normal mammalian cells at the molecular level as well as cellular and subcellular levels, including plasma membrane, cytoskeleton, and membrane-bound organelles such as lysosomes, mitochondria, nucleus, endoplasmic reticulum, and peroxisome. In parallel, we assemble the knowledge about the interactions of graphene-based materials with cancerous cells, that are considered as the potential applications of these materials for cancer therapy including metastasis treatment, targeted drug delivery, and differentiation to non-cancer stem cells. We highlight the influence of key parameters, such as the size and surface chemistry of graphene-based materials that govern the efficiency of internalization and biocompatibility of these particles in vitro and in vivo. Finally, this review aims to correlate the key parameters of graphene-based nanomaterials specially graphene oxide, such as size and surface modifications, to their interactions with the cancerous and non-cancerous cells for designing and engineering them for bio-applications and especially for therapeutic purposes

A flexible multifunctional electrode based on conducting PANI/Pd composite for non-enzymatic glucose sensor and direct alcohol fuel cell applications

In this work, we fabricated a flexible, multifunctional polyimide (PI)/Au-polyaniline (PAN)/Pd nanocomposite electrode with excellent electrochemical properties. Structural geometry, morphological views, and functional group analyses indicated that the physicochemical and electrochemical performance of the electrode is based on the strong and synergistic metal-polymer interaction between the conducting PAN and Pd, which ensured high conductivity, rapid response, and high electron transfer rate through more electroactive spots available in the nanocomposite. Here, we demonstrated that the fabricated PI/Au-PAN/Pd electrodes can be successfully used for biomedical sensing of glucose, as well as for energy conversion application, using the oxidation of alcohols such as methanol and ethanol in fuel cells. The electrochemical analysis shows that the flexible sensor (PI/Au-PAN/Pd) has ultra-high sensitivity of 2140 μA/μM.cm2 with a low detection limit of 0.3 μM for glucose. Also, the interference analysis, reproducibility, and stability studies reveal its excellent capability for glucose sensing. Furthermore, the electrode also demonstrates prominent electrocatalytic behavior to the electrooxidation of methanol and ethanol in an alkaline medium with a current density of 3 mA/cm2 and 0.96 mA/cm2 along with good cyclic stability. Thus, this efficient flexible electrocatalyst with good stability, practicability, and reproducibility claims its potential applications in flexible/wearable healthcare diagnostics systems as well as in alternative energy conversion devices

Enriched microbial communities for ammonium and nitrite removal from recirculating aquaculture systems

The aim of this study was the enrichment of high-performance microbial communities in biofilters for removal of ammonium and nitrite from aquaculture water. Ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) were enriched from different environmental water samples. The microbial communities with higher ammonium and nitrite removal activity were selected and adapted to different temperatures [9 \ub0C, 15 \ub0C, room temperature (25 \ub0C), and 30 \ub0C]. The expression of genes involved in nitrification including ammonia monooxygenase (AMO) and nitrite oxidoreductase (NXR) were measured in temperature-adapted AOB and NOB microbiomes. The microbial species present in the selected microbiomes were identified via 16s rRNA sequencing. The microbial communities containing Nitrosomonas oligotropha and Nitrobacter winogradskyi showed the highest ammonium and nitrite removal activity at all temperatures used for adaptation. Furthermore, the microbial communities do not contain any pathogenic bacteria. They also exhibited the highest expression of AMO and NXR genes. Using the enriched microbial communities, we achieved a 288% and 181% improvement in ammonium and nitrite removal over the commonly used communities in biofilters at 9 \ub0C, respectively. These results suggest that the selected microbiomes allowed for a significant improvement of water quality in a recirculating aquaculture system (RAS)

Polydopamine/graphene oxide coatings loaded with tetracycline and green Ag nanoparticles for effective prevention of biofilms

Bacterial adhesion and biofilm formation are significant challenges for medical devices and implants. Surface modification to alter the surface properties of biomedical device surfaces to prevent the biofilm formation is an important driving force for the development of anti-biofilm coatings. Here, a simple and feasible method to fabricate antibacterial coatings that combines the adhesion properties of polydopamine (PDA) and the high drug loading capacity of graphene oxide (GO). Tetracycline and green-synthesized silver nanoparticles were successfully assembled onto the coating surface, endowing the coating an anti-biofilm effect and exhibit strong inhibitory effect on S. aureus and E. coli biofilms by a factor of more than 1000 (3 log10 units). Kirby-Bauer diffusion test, colony forming unit (CFU) counts, biofilm topography studies and live/dead staining were used to evaluate the antibacterial activity of the coatings. This study is proposed that PDA/GO coatings loaded with antibiotics or silver nanoparticles can be used as a potential approach to prevent infection associated with implantable biomedical devices