Fluorescent Carbon Dots for Sensitive and Rapid Monitoring of Intracellular Ferrous Ion

Although iron is an essential constituent for almost all living organisms, iron dyshomeostasis at a cellular level may trigger oxidative stress and neuronal damage. Hence, there are numerous reported carbon dots (CDs) that have been synthesized and applied to determine intracellular iron ions. However, among reported CDs focused to detect Fe3+ ions, only a few CDs have been designed to specifically determine Fe2+ ions over Fe3+ ions for monitoring of intracellular Fe2+ ions. We have developed the nitrogen-doped CDs (NCDs) for fluorescence turn-off detection of Fe2+ at cellular level. The as-synthesized NCDs exhibit a strong blue fluorescence and low cytotoxicity, acting as fluorescence probes to detect Fe2+ as low as 0.702 µM in aqueous solution within 2 min and visualize intracellular Fe2+ in the concentration range from 0 to 500 µM within 20 min. The as-prepared NCDs possess some advantages such as high biocompatibility, strong fluorescence properties, selectivity, and rapidity for intracellular Fe2+ monitoring, making NCDs an excellent nanoprobe for biosensing of intracellular ferrous ions.

The Synergistic Reducing Drug Resistance Effect of Cisplatin and Ursolic Acid on Osteosarcoma through a Multistep Mechanism Involving Ferritinophagy

Increasing evidence suggests that traditional Chinese medicine strategies are obviously beneficial for cancer treatment, but scientific research on the underlying molecular mechanisms is lacking. We report that ursolic acid, a bioactive ingredient isolated from Radix Actinidiae chinensis, has strong antitumour effects on osteosarcoma cells. Functional studies showed that ursolic acid inhibited tumour cell proliferation and promoted the apoptosis of a variety of osteosarcoma cells. Ursolic acid had a synergistic cytotoxic effect with cisplatin on osteosarcoma cells. In a mouse osteosarcoma xenograft model, low-dose cisplatin combined with ursolic acid significantly reduced tumour growth. Notably, ursolic acid reversed weight loss in mice treated with cisplatin. Mechanistic studies showed that ursolic acid degraded ferritin by activating autophagy and induced intracellular overload of ferrous ions, leading to ferroptosis. In addition, ursolic acid enhanced the DNA-damaging effect of cisplatin on osteosarcoma cells. Taken together, these findings suggest that ursolic acid is a nontoxic adjuvant that may enhance the effectiveness of chemotherapy in osteosarcoma.

Dexmedetomidine is Resistant to Ferroptosis by Activating mTOR-TFR1 Signaling

Background: With the development of society, Neurodegenerative disease (ND), such as alzheimer's disease, is more and more important to the researchers. Metal iron may play a crucial role in this disease, so our research constructed the iron overloading model in nerve cells, induce the ferroptosis, simulate the state of the nerve in the body, and used the anesthesia Dexmedetomidine (Dex), and study whether the Dex can inhibit the ferroptosis and reduce the ND.Methods: Cell proliferation kit CCK8 and PI/Hoechst fluorescence double staining were used to detect the proliferation and apoptosis of HT22 cells. Western blot (WB) was used to detect the expression of PTGS2 and ACSL4, pathway proteins mTOR, TFR1. ROS content in HT22 cells was determined by DHE fluorescence probe. Lipid Peroxidation in nerve cells was detected by MDA Assay. Mito-ferrorange fluorescent probe was used to detect the level of ferrous ions in cells to demonstrate that ferroptosis occurred in nerve cells and Dex could protect nerve cells from ferroptosis.Results: Dex inhibits ferroptosis by regulating the mTOR-TFR1 pathway, reducing lipid peroxidation, intracellular reactive oxygen accumulation (ROS), reducing iron ions, and alleviating mitochondrial damage. mTOR is a well-known autophagy target and has been found to be closely related to ferroptosis. Dex activates the mTOR pathway, inhibits iron entry into the cell, reduces iron influx, and prevents ferroptosis by fenton reaction between excessive iron and lipids in the cell.Conclusion: Dex protects nerve cells from ferroptosis by regulating the mTOR-TFR1 pathway.

Induced Polyspecificity of Human Secretory Immunoglobulin A Antibodies: Is It Possible to Improve Their Ability to Bind Pathogens?

<b><i>Introduction:</i></b> As has been shown previously, various protein-modifying agents can change the antigen-binding properties of immunoglobulins. However, induced polyspecificity of human secretory immunoglobulin A (sIgA) has not been previously characterized in detail. <b><i>Methods:</i></b> In the present study, human secretory immunoglobulin A (IgA) was exposed to buffers with acidic pH, to free heme, or to pro-oxidative ferrous ions, and the antigen-binding behavior of the native and modified IgA to viral and bacterial antigens was compared using Western blotting and enzyme-linked immunosorbent assay. The ability of these agents to modulate the antigen-binding properties of human sIgA toward a wide range of pathogen peptides was investigated using an epitope microarray. <b><i>Results:</i></b> We have shown that acidic pH, heme, and pro-oxidative ferrous ions influenced the binding of secretory IgA in opposite directions (either increasing or decreasing); however, the strongest effect was observed when using buffers with low pH. This fraction had the highest number of affected reactivities; most of them were increased and most of the new ones were toward common pathogens. <b><i>Conclusions:</i></b> Thus, it was shown that all investigated treatments can alter to some degree the antigen-binding of secretory IgA, but acidic pH has the most potentially beneficial effect by increasing binding to a largest number of common pathogens’ antigens.

Cephalexin removal by persulfate activation using simulated sunlight and ferrous ions

This study presents the main results related to the use of activated persulfate (PS) in the elimination of the beta-lactam antibiotic cephalexin (CPX). Experiments were done using K2S2O8 and simulated sunlight. A face-centered central composite experimental design was used to analyze the effects of the solution pH and the PS concentration on the reaction, and to determine the optimized conditions that favor the CPX elimination. The results indicated that the removal of CPX is promoted by an acidic pH and under the higher evaluated PS dose (7.5 mg L−1). CPX total removal was achieved in 30 min. The analysis of the effect of the pollutant initial concentration indicated that a pseudo-first order kinetic model can be used to describe the reaction. Likewise, the use of Fe2+ ions for PS activation (in the dark) was evaluated and allowed to establish that a higher concentration of ions favors the pollutant removal. Control tests and under the presence of scavenger agents indicated that both HO• and SO4−• radicals would be present in the solution and promote the CPX elimination. The assessment of the solution dissolved organic carbon, nitrates and sulfates was also carried out, and indicated that a portion of the organic matter was mineralized.

Regulation and Functional Complexity of the Chlorophyll-Binding Protein IsiA

As the oldest known lineage of oxygen-releasing photosynthetic organisms, cyanobacteria play the key roles in helping shaping the ecology of Earth. Iron is an ideal transition metal for redox reactions in biological systems. Cyanobacteria frequently encounter iron deficiency due to the environmental oxidation of ferrous ions to ferric ions, which are highly insoluble at physiological pH. A series of responses, including architectural changes to the photosynthetic membranes, allow cyanobacteria to withstand this condition and maintain photosynthesis. Iron-stress-induced protein A (IsiA) is homologous to the cyanobacterial chlorophyll (Chl)-binding protein, photosystem II core antenna protein CP43. IsiA is the major Chl-containing protein in iron-starved cyanobacteria, binding up to 50% of the Chl in these cells, and this Chl can be released from IsiA for the reconstruction of photosystems during the recovery from iron limitation. The pigment–protein complex (CPVI-4) encoded by isiA was identified and found to be expressed under iron-deficient conditions nearly 30years ago. However, its precise function is unknown, partially due to its complex regulation; isiA expression is induced by various types of stresses and abnormal physiological states besides iron deficiency. Furthermore, IsiA forms a range of complexes that perform different functions. In this article, we describe progress in understanding the regulation and functions of IsiA based on laboratory research using model cyanobacteria.

Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 1

The present review, consisting of two parts, considers the application of the chemiluminescence detection method in evaluating free radical reactions in biological model systems. The first part presents a classification of experimental biological model systems. Evidence favoring the use of chemiluminescence detection in the study of free radical reactions, along with similar methods of registering electromagnetic radiation as electron paramagnetic resonance, spectrophotometry, detection of infrared radiation (IR spectrometry), and chemical methods for assessing the end products of free radical reactions, is shown. Chemiluminescence accompanying free radical reactions involving lipids has been the extensively studied reaction. These reactions are one of the key causes of cell death by either apoptosis (activation of the cytochrome c complex with cardiolipin) or ferroptosis (induced by free ferrous ions). The concept of chemiluminescence quantum yield is also discussed in this article. The second part, which is to be published in the next issue, analyzes the application of chemiluminescence detection using luminescent additives that are called activators, a.k.a. chemiluminescence enhancers, and enhance the emission through the tripletsinglet transfer of electron excitation energy from radical reaction products, followed by light emission with a high quantum yield.

Textile Wastewater Treatment in a Spinning Disc Reactor: Improved Performances—Experimental, Modeling and SVM Optimization

The paper presents an experimental study regarding the treatment of a real textile wastewater using the spinning disc (SD) technology, either individually or associated with an advanced Fenton oxidation step. The SD efficiency was investigated by studying the color, suspended solids, or turbidity removals, at distinctive feeding flowrates (10–30 L/h) and disc rotating speeds (100–1500 rpm). The data revealed increasing removal trends and allowed to establish the highest removal values. Based on obtained experimental results, the wastewater treatment efficiency by SD technology was reasonably good and thus, the WW indicators can be improved within relatively short periods of time. Additionally, based on supervised learning algorithms, the study includes treatment modeling for turbidity and color removal, followed by turbidity removal optimization relying on the best learned models. Satisfactory results obtained with the modeling and optimization procedures provide useful predictions for the approached treatment processes. Furthermore, within this study, a Fenton oxidation process was applied to SD technology to minimize the color and solids content. The influence of pH, hydrogen peroxide and ferrous ions concentrations was also investigated in order to establish the highest removal efficiencies. Overall, the SD technology applied in textile effluents treatment proved to be an appropriate and efficient alternative to classical mechanical step applied within the primary treatment step and, when associated with an advanced oxidative process in the secondary step, rendered good improvement, namely of 62.84% and 69.46% for color and respectively, suspended solids removal.