Iron protoporphyrin IX-hyaluronan hydrogel-supported luminol chemiluminescence for the detection of nitric oxide in physiological solutions.

Due to its role as a free radical signal-transducing agent with a short lifespan, precise measurement of nitric oxide (●NO) levels presents significant challenges. Various analytical techniques offer distinct advantages and disadvantages for ●NO detection. This research aims to simplify the detection process by developing a hydrogel system using iron(III)-protoporphyrin IX (hemin)-loaded hyaluronan for the detection of ●NO in solution. Various hydrogel formulations were created, and the effects of their components on hydrogel-supported luminol chemiluminescence (CL) kinetics, radical scavenging, and physicochemical properties were analysed through factorial analysis. The candidate formulations were then evaluated using two ●NO donors. An increase in the degree of crosslinking in unloaded formulations enhanced interactions with the CL reaction components, hydrogen peroxide (H2O2) and luminol, thereby affecting light generation. However, hemin loading negated these effects, resulting in more prominent luminescence kinetics in formulations with lower crosslinking degrees. Similarly, ●NO influenced the kinetics differently, interacting with both the CL reaction and hydrogel components. Hemin-loaded formulations exhibited enhanced signal propagation when exposed to ●NO, followed by H2O2 and luminol, whereas reversing the order of addition inhibited this propagation. The magnitude of these luminescence changes depended on the type and concentration of the ●NO donor, demonstrating greater sensitivity to ●NO levels compared to amperometric sensing. These findings suggest that the studied hydrogel platform has potential for the facile and accurate detection of ●NO in solution, requiring minimal sample sizes.

Anticancer Effect of Hemin through ANO1 Inhibition in Human Prostate Cancer Cells.

Anoctamin1 (ANO1), a calcium-activated chloride channel, is overexpressed in a variety of cancer cells, including prostate cancer, and is involved in cancer cell proliferation, migration, and invasion. Inhibition of ANO1 in these cancer cells exhibits anticancer effects. In this study, we conducted a screening to identify novel ANO1 inhibitors with anticancer effects using PC-3 human prostate carcinoma cells. Screening of 2978 approved and investigational drugs revealed that hemin is a novel ANO1 inhibitor with an IC50 value of 0.45 µM. Notably, hemin had no significant effect on intracellular calcium signaling and cystic fibrosis transmembrane conductance regulator (CFTR), a cyclic AMP (cAMP)-regulated chloride channel, and it showed a weak inhibitory effect on ANO2 at 3 µM, a concentration that completely inhibits ANO1. Interestingly, hemin also significantly decreased ANO1 protein levels and strongly inhibited the cell proliferation and migration of PC-3 cells in an ANO1-dependent manner. Furthermore, it strongly induced caspase-3 activation, PARP degradation, and apoptosis in PC-3 cells. These findings suggest that hemin possesses anticancer properties via ANO1 inhibition and could be considered for development as a novel treatment for prostate cancer.

(-)-Epigallocatechin gallate as an inhibitor of hemoglobin-catalyzed lipid oxidation: molecular mechanism of action and nutritional application.

Hemoglobin (Hb) is effective inducer for lipid oxidation and protein-polyphenol interaction is a well-known phenomenon. The effects of the interaction of (-)-epigallocatechin gallate (EGCG) with Hb on lipid oxidation were rarely elucidated. The detailed interaction between bovine Hb and EGCG was systematically explored by experimental and theoretical approaches, to illustrate the molecular mechanisms by which EGCG influenced the redox states and stability of Hb. EGCG would bind to the central pocket of protein with one binding site to form Hb-EGCG complex. The binding constant for Hb-EGCG complex was 0.34 × 104 M-1 at 277 K, and thermodynamic parameters (ΔH > 0, ΔS > 0 and ΔG < 0) revealed the participation of hydrophobic forces in the binding process. The binding of EGCG would increase the compactness of protein molecule and diminish the crevice near the heme cavity, which was responsible for the reduction of met-Hb to oxy-Hb and inhibition of hemin release from met-Hb. Moreover, EGCG efficiently suppressed Hb-caused lipid oxidation in liposomes and cod muscles, which was possibly attributed to the reduction to oxy-Hb state and declined hemin dissociation from met-Hb. Altogether, our results provide significant insights into the binding of EGCG to redox-active Hb, which represents a novel mechanism for the anti-oxidant capacity of EGCG in human health and is favorable to the applications of natural EGCG in the good quality of Hb-containing products.

A thiophene functionalized Hf(IV) organic framework for the detection of anti-neoplastic drug flutamide and biomolecule hemin and catalysis of Friedel-Crafts alkylation.

Development, rapid detection and quantification of anticancer drugs in biological samples are crucial for effective drug monitoring. The present work describes the design of a metal-organic framework (MOF) between Hf(IV) ion and 2-(thiophene-2-carboxamido)terephthalic acid linker (surface area = 571 m² g-1). Desolvated 1' displayed highly discriminative fluorescence sensing property for the anti-neoplastic drug flutamide and biomolecule hemin in aqueous medium in the presence of co-exiting biomolecules and ions. The MOF's response time for sensing flutamide and hemin was less than 5 s with low detection limits 1.5 and 0.08 nM respectively. Additionally, the MOF also demonstrated recyclability up to five cycles and maintained its sensing ability across different pH media, various water samples, and biological fluids. Experimental and theoretical analyses suggested photoinduced electron transfer and inner-filter effect in the presence of flutamide and Förster resonance energy transfer in the presence of hemin are most likely reasons behind the fluorescence quenching of MOF. Furthermore, the MOF demonstrated catalytic activity in Friedel-Crafts alkylation reactions, providing a 96% yield with slight decay in its activity over four uses. The enhanced activity of 1' is due to the functionalized thiophene moities through hydrogen bond donating sites, confirmed by series of control experiments.

Enzyme-free and rapid colorimetric analysis of osteopontin via triple-helix aptamer probe coupled with catalytic hairpin assembly reaction.

BACKGROUND: Osteopontin (OPN) is closely associated with tumorigenesis, growth, invasion, and immune escape and it serves as a plasma biomarker for hepatocellular carcinoma (HCC). Nevertheless, the accurate and rapid detection of low-abundance OPN still poses significant challenges. Currently, the majority of protein detection methods rely heavily on large precision instruments or involve complex procedures. Therefore, developing a simple, enzyme-free, rapid colorimetric analysis method with high sensitivity is imperative. RESULTS: In this study, we have developed a portable colorimetric biosensor by integrating the triple-helix aptamer probe (THAP) and catalytic hairpin assembly (CHA) strategy, named as T-CHA. After binding to the OPN, the trigger probe can be released from THAP, then initiates the CHA reaction and outputs the signal through the formation of a G-quadruplex/Hemin DNAzyme with horseradish peroxidase-like activity. Consequently, this colorimetric sensor achieves visual free-labeled detection without additional fluorophore modification and allows for accurate quantification by measuring the optical density of the solution at 650 nm. Under optimal conditions, the logarithmic values of various OPN concentrations exhibit satisfactory linearity in the range of 5 pg mL-1 to 5 ng mL-1, with a detection limit of 2.04 pg mL-1. Compared with the widely used ELISA strategy, the proposed T-CHA strategy is rapid (∼105 min), highly sensitive, and cost-effective. SIGNIFICANCE: The T-CHA strategy, leveraging the low background leakage of THAP and the high catalytic efficiency of CHA, has been successfully applied to the detection of OPN in plasma, demonstrating significant promise for the early diagnosis of HCC in point-of-care testing. Given the programmability of DNA and the universality of T-CHA, it can be readily modified for analyzing other useful tumor biomarkers.

Hemin enhances the 5-aminolevulinic acid-photodynamic therapy effect through the changes of cellular iron homeostasis.

BACKGROUND: Photodynamic therapy (PDT) has been utilized as a promising alternative cancer treatment due to its minimum invasiveness over the years. Exogenous 5-aminolevulinic acid (ALA) triggers protoporphyrin IX (PpIX) accumulation, which happens in cancer cells. However, certain types of cancer exhibit reduced effectiveness in the PpIX accumulation mechanism. This study aimed to determine the effect of ALA-PDT combination with hemin on gastric carcinoma TMK-1 cells. METHODS: This study utilized TMK-1 gastric cancer cell line to evaluate PpIX, ROS, and Fe2+ accumulation following the administration of ALA, hemin, and a combination of ALA and hemin PDT. We also evaluate the mRNA expressions related to iron homeostasis and treatment impacts on cell viability. RESULTS: The co-addition of ALA and hemin PDT for 4 h of treatment resulted in a significant decrease in cell viability by up to 18 %. While ALA-PDT enhanced PpIX metabolism, the addition of hemin influenced both the production of reactive oxygen species (ROS) and cellular iron homeostasis by inducing Fe2+ accumulation and affecting mRNA levels of IRP, Tfr1, Ferritin, NFS1, and SDHB. CONCLUSION: These findings suggest that the addition of ALA and hemin enhances phototoxicity in TMK-1 cells. The combination of ALA and hemin with PDT induces cell death, evidenced by increased cytotoxicity properties such as PpIX and ROS, along with significant changes in TMK-1 gastric cancer iron homeostasis. Therefore, the combination of ALA and hemin could be one of the alternatives in photodynamic therapy for cancer in the future.

A Cost-Effective Hemin-Based Artificial Enzyme Allows for Practical Applications.

Nanomaterials excel in mimicking the structure and function of natural enzymes while being far more interesting in terms of structural stability, functional versatility, recyclability, and large-scale preparation. Herein, the story assembles hemin, histidine analogs, and G-quadruplex DNA in a catalytically competent supramolecular assembly referred to as assembly-activated hemin enzyme (AA-heminzyme). The catalytic properties of AA-heminzyme are investigated both in silico (by molecular docking and quantum chemical calculations) and in vitro (notably through a systematic comparison with its natural counterpart horseradish peroxidase, HRP). It is found that this artificial system is not only as efficient as HRP to oxidize various substrates (with a turnover number kcat of 115 s-1) but also more practically convenient (displaying better thermal stability, recoverability, and editability) and more economically viable, with a catalytic cost amounting to <10% of that of HRP. The strategic interest of AA-heminzyme is further demonstrated for both industrial wastewater remediation and biomarker detection (notably glutathione, for which the cost is decreased by 98% as compared to commercial kits).

Near-infrared light-driven lab-on-paper cathodic photoelectrochemical aptasensing for di(2-ethylhexyl)phthalate based on AgInS2/Cu2O/FeOOH photocathode.

Di(2-ethylhexyl)phthalate (DEHP) is commonly released from plastics in aqueous environment, which can disrupt endocrine system and cause adverse effects on public health. There is a pressing need to highly sensitive detect DEHP. Herein, a near-infrared (NIR) light-driven lab-on-paper cathodic photoelectrochemical aptasensing platform integrated with AgInS2/Cu2O/FeOOH photocathode and "Y"-like ternary conjugated DNA nanostructure-mediated "ON-OFF" catalytic switching of hemin monomer-to-dimer was established for ultrasensitive DEHP detection. Profiting from the collaborative roles of the effective photosensitization of NIR-response AgInS2 and the fast hole extraction of FeOOH, the NIR light-activated AgInS2/Cu2O/FeOOH photocathode generated a markedly enhanced photocathodic signal. The dual hemin-labelled "Y"-like ternary conjugated DNA nanostructures made the hemin monomers separated in space and they maintained highly active to catalyze in situ generation of electron acceptors (O2). The hemin monomers were relocated in close proximity with the help of target-induced allosteric change of DNA nanostructures, which could spontaneously dimerize into catalytically inactive hemin dimers and fail to mediate electron acceptors generation, resulting in a decreased photocathodic signal. Therefore, the ultrasensitive DEHP detection was realized with a linear response range of 1 pM-500 nM and a detection limit of 0.39 pM. This work rendered a promising prototype to construct powerful paper-based photocathodic aptasensing system for sensitive and accurate screening of DEHP in aqueous environment.

Dietary Hemin Remodels Gut Microbiota and Mediates Tissue Inflammation and Injury in the Small Intestine.

SCOPE: Epidemiological studies have linked excessive red and processed meat intake to gut disorders. Under laboratory conditions, high heme content is considered the primary health risk factor for red meat. However, heme in meat is present in myoglobin, which is an indigestible protein, suggesting the different functions between myoglobin and heme. This study aims to explore how dietary myoglobin and heme affect gut health and microbiota differently. METHODS AND RESULTS: Histological and biochemical assessments as well as 16S rRNA sequencing are performed. Moderate myoglobin intake (equivalent to the recommended intake of 150 g meat per day for human) has beneficial effects on the duodenal barrier. However, a too high myoglobin diet (equivalent to intake of 3000 g meat per day for human) triggers duodenum injury and alters the microbial community. The hemin diet destroys intestinal tissue and ileal microbiota more significantly. The in vitro experiments further confirm that free heme exhibits high toxicity to beneficial gut bacteria while myoglobin promotes the growth and metabolism of Limosilactobacillus reuteri. CONCLUSION: Moderate intake of myoglobin or hemin is beneficial to intestinal health and microbiota, but too high amounts lead to tissue inflammation and injury in the small intestine by reshaping ileal microbiota.

Hydroxychloroquine inhibits hemolysis-induced arterial thrombosis ex vivo and improves lung perfusion in hemin-treated mice.

BACKGROUND: Free labile hemin acts as a damage-associated molecular pattern during acute and chronic hemolysis and muscle injury, supporting platelet activation and thrombosis. OBJECTIVES: To investigate the anti-thrombotic potential of hydroxychloroquine on hemolysis-induced platelet activation and arterial thrombosis. METHODS: The effect of hydroxychloroquine on hemin-induced platelet activation and hemolysis-induced platelet recruitment and aggregation was measured in washed platelets and hemolyzed blood, respectively. Its effect on ferric-chloride (FeCl3)-induced arterial thrombosis and lung perfusion following hemin injection was assessed in wild-type mice. RESULTS: Erythrocyte lysis and endothelial cell activation cooperatively supported platelet aggregation and thrombosis at arterial shear stress. This thrombotic effect was reversed by hydroxychloroquine. In a purified system, hydroxychloroquine inhibited platelet build-up on immobilized von Willebrand factor in hemolyzed blood without altering initial platelet recruitment. Hydroxychloroquine inhibited hemin-induced platelet activation and phosphatidylserine exposure independently of reactive oxygen species generation. In the presence of hemin, hydroxychloroquine did not alter glycoprotein VI shedding but reduced C-type-lectin-like-2 expression on platelets. In vivo, hydroxychloroquine reversed pulmonary perfusion decline induced by exogenous administration of hemin. In arterial thrombosis models, hydroxychloroquine inhibited ferric-chloride-induced thrombosis in the carotid artery and reduced von Willebrand factor accumulation in the thrombi. CONCLUSION: Hydroxychloroquine inhibited hemolysis-induced arterial thrombosis ex vivo and improved pulmonary perfusion in hemin-treated mice, supporting a potential benefit of its use as an adjuvant therapy in hemolytic diseases to limit arterial thrombosis and to improve organ perfusion.

Unveiling the Chameleon: A Case Report on Acute Intermittent Porphyria.

Acute intermittent porphyria (AIP) is a rare autosomal dominant metabolic disorder with low penetrance, often presenting with a broad spectrum of clinical manifestations. Acute neurovisceral attacks commonly occur in young women, mimicking signs and symptoms of other medical and psychiatric conditions, thus delaying the diagnosis. We present the case of an 18-year-old female college student with recurrent hospitalizations for intractable abdominal pain, now again with pain and new subjective hematuria. The patient had previously undergone an endoscopy/colonoscopy with negative biopsies and serologies for acute pathology, including celiac disease. Celiac studies were repeated, given the possibility of inadvertent gluten exposure before the onset of the latest symptoms, but were negative. Basic labs and repeat imaging, including contrast-enhanced CT, MRI, and magnetic resonance (MR) enterography of the abdomen, continued to be unremarkable, and the patient's symptoms were felt to be functional in etiology. The patient's urinalysis was normal, and pregnancy was also ruled out. The patient continued to have pain despite receiving opiate analgesics, thus prompting a psychiatry consultation. She was diagnosed with acute adjustment disorder with anxiety and was started on hydroxyzine. Due to persistent symptoms, serum and urine samples were sent, revealing low levels of porphobilinogen deaminase (PBGD) and hydroxymethylbilane synthase (HMBS) gene mutation, confirming the diagnosis of AIP. She was treated with oral glucose and outpatient IV hemin infusions with the resolution of symptoms. AIP presents a nonspecific and highly variable clinical picture, often making it a challenging diagnosis due to such a broad differential. While our patient was thought to have acute adjustment disorder due to an unremarkable initial workup, further testing revealed otherwise. This case demonstrates how clinicians must have a high suspicion of AIP when caring for young females, manifesting with neurovisceral and psychiatric signs and symptoms. Timely diagnosis improves a patient's quality of life and can decrease overutilization of healthcare resources.

Label-free and portable detection of HIV-DNA by a handheld luminometer.

BACKGROUND: The human immunodeficiency virus (HIV) remains a major worldwide health problem. Nowadays, many methods have been developed for quantitative detecting human immunodeficiency virus DNA (HIV-DNA), such as fluorescence and colorimetry. However, these methods still have the disadvantages of being expensive and requiring professional technicians. Early diagnosis of pathogens is increasingly dependent on portable instruments and simple point-of-care testing (POCT). Therefore, it is meaningful and necessary to develop portable and cheap methods for detecting disease markers. RESULTS: In this work, a label-free chemiluminescence (CL) method was developed for detecting HIV-DNA via a handheld luminometer. To achieve label-free target detection, the CL catalyst, G-triplex-hemin DNAzyme (G3-hemin DNAzyme), was in-situ assembled in the presence of HIV-DNA. For improving sensitivity, HIV-DNA induced the cyclic strand displacement reaction (SDR), which can form three G3-hemin DNAzymes in one cycle. So, the chemiluminescence reaction between luminol and H2O2 was highly effectively catalyzed, and the CL intensity was linearly related with the concentration of HIV-DNA in the range of 0.05-10 nM with a detection limit of 29.0 pM. Due to the high specificity of hairpin DNA, single-base mismatch can be discriminated, which ensured the specific detection of HIV-DNA. SIGNIFICANCE: In-situ formation of G3-hemin DNAzyme led to label-free and selective detection without complex synthesis and functionalization. Therefore, it offers a cheap, selective, sensitive and portable method for detecting disease-related genes, which is promising for POCT of clinical diagnosis in resource-limited settings.

CRISPR-Cas13a-Triggered DNAzyme Signal Amplification-Based Colorimetric miRNA Detection Method and Its Application in Evaluating the Anxiety.

The development of a bio-sensing strategy based on CRISPR/Cas that is exceptionally sensitive is crucial for the identification of trace molecules. Colorimetric miRNA detection utilizing CRISPR/Cas13a-triggered DNAzyme signal amplification was described in this article. The developed strategy was implemented for miRNA-21 detection as a proof of concept. The cleavage activity of Cas13a was triggered when the target molecule bonded to the Cas13a-crRNA complex and cleaved uracil ribonucleotides (rU) in the substrate probe. As a consequence, the S chain was liberated from the T chain that had been modified on magnetic beads (MB). The G-rich sections were then exposed when the catalytic hairpin assembly between the H1 and H2 probes was activated by the released T@MB. G-rich section can fold into G-quadruplex. By catalyzing the formation of green ABTS3- via HRP-mimicking G-quadruplex/hemin complexes, colorimetric measurements of miRNA can be achieved visually through DNAzyme-mediated signal amplification. The method demonstrated a low limit of detection of 27 fM and a high selectivity towards target miRNA eventually. As a result, the developed strategy provides a clinical application platform for the detection of miRNAs that is both ultrasensitive and extremely specific.

HemU and TonB1 contribute to hemin acquisition in Stenotrophomonas maltophilia.

Introduction: The hemin acquisition system is composed of an outer membrane TonB-dependent transporter that internalizes hemin into the periplasm, periplasmic hemin-binding proteins to shuttle hemin, an inner membrane transporter that transports hemin into the cytoplasm, and cytoplasmic heme oxygenase to release iron. Fur and HemP are two known regulators involved in the regulation of hemin acquisition. The hemin acquisition system of Stenotrophomonas maltophilia is poorly understood, with the exception of HemA as a TonB-dependent transporter for hemin uptake. Methods: Putative candidates responsible for hemin acquisition were selected via a homolog search and a whole-genome survey of S. maltophilia. Operon verification was performed by reverse transcription-polymerase chain reaction. The involvement of candidate genes in hemin acquisition was assessed using an in-frame deletion mutant construct and iron utilization assays. The transcript levels of candidate genes were determined using quantitative polymerase chain reaction. Results: Smlt3896-hemU-exbB2-exbD2-tonB2 and tonB1-exbB1-exbD1a-exbD1b operons were selected as candidates for hemin acquisition. Compared with the parental strain, hemU and tonB1 mutants displayed a defect in their ability to use hemin as the sole iron source for growth. However, hemin utilization by the Smlt3896 and tonB2 mutants was comparable to that of the parental strain. HemA expression was repressed by Fur in iron-replete conditions and derepressed in iron-depleted conditions. HemP negatively regulated hemA expression. Like hemA, hemU was repressed by Fur in iron-replete conditions; however, hemU was moderately derepressed in response to iron-depleted stress and fully derepressed when hemin was present. Unlike hemA and hemU, the TonB1-exbB1-exbD1a-exbD1b operon was constitutively expressed, regardless of the iron level or the presence of hemin, and Fur and HemP had no influence on its expression. Conclusion: HemA, HemU, and TonB1 contribute to hemin acquisition in S. maltophilia. Fur represses the expression of hemA and hemU in iron-replete conditions. HemA expression is regulated by low iron levels, and HemP acts as a negative regulator of this regulatory circuit. HemU expression is regulated by low iron and hemin levels in a hemP-dependent manner.

Efficient chemiluminescence of luminol in the presence of hemin without added hydrogen peroxide†.

The results reported herein demonstrate for the first time that typical reducing agents in an alkaline medium initiate chemiluminescence of luminol in the presence of hemin, and the efficiency of their action is comparable to that of hydrogen peroxide and exceeds it in the case of the superoxide anion. The pertinent implications of these findings refer to new possibilities for developing chemiluminescence assays and biosensors and to precautions for determining hydrogen peroxide using luminol and hemin in samples of unknown composition, most prominently, of biological origin.

The Pharmacological Effect of Hemin in Inflammatory-Related Diseases: A Systematic Review.

BACKGROUND: Hemin is clinically used in acute attacks of porphyria; however, recent evidence has also highlighted its capability to stimulate the heme oxygenase enzyme, being associated with cytoprotective, antioxidant, and anti-inflammatory effects. Indeed, current preclinical evidence emphasizes the potential anti-inflammatory role of hemin through its use in animal models of disease. Nevertheless, there is no consensus about the underlying mechanism(s) and the most optimal therapeutic regimens. Therefore, this review aims to summarize, analyze, and discuss the current preclinical evidence concerning the pharmacological effect of hemin. METHODS: Following the application of the search expression and the retrieval of the articles, only nonclinical studies in vivo written in English were considered, where the potential anti-inflammatory effect of hemin was evaluated. RESULTS: Forty-nine articles were included according to the eligibility criteria established. The results obtained show the preference of using 30 to 50 mg/kg of hemin, administered intraperitoneally, in both acute and chronic contexts. This drug demonstrates significant anti-inflammatory and antioxidant activities considering its capacity for reducing the expression of proinflammatory and oxidative markers. CONCLUSIONS: This review highlighted the significant anti-inflammatory and antioxidant effects of hemin, providing a clearer vision for the medical community about the use of this drug in several human diseases.

Exogenous Hemin enhances the antioxidant defense system of rice by regulating the AsA-GSH cycle under NaCl stress.

Abiotic stress caused by soil salinization remains a major global challenge that threatens and severely impacts crop growth, causing yield reduction worldwide. In this study, we aim to investigate the damage of salt stress on the leaf physiology of two varieties of rice (Huanghuazhan, HHZ, and Xiangliangyou900, XLY900) and the regulatory mechanism of Hemin to maintain seedling growth under the imposed stress. Rice leaves were sprayed with 5.0 µmol·L-1 Hemin or 25.0 µmol·L-1 ZnPP (Zinc protoporphyrin IX) at the three leaf and one heart stage, followed by an imposed salt stress treatment regime (50.0 mmol·L-1 sodium chloride (NaCl)). The findings revealed that NaCl stress increased antioxidant enzymes activities and decreased the content of nonenzymatic antioxidants such as ascorbate (AsA) and glutathione (GSH). Furthermore, the content of osmoregulatory substances like soluble proteins and proline was raised. Moreover, salt stress increased reactive oxygen species (ROS) content in the leaves of the two varieties. However, spraying with Hemin increased the activities of antioxidants such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) and accelerated AsA-GSH cycling to remove excess ROS. In summary, Hemin reduced the effect of salt stress on the physiological characteristics of rice leaves due to improved antioxidant defense mechanisms that impeded lipid peroxidation. Thus, Hemin was demonstrated to lessen the damage caused by salt stress.

DMT1 ubiquitination by Nedd4 protects against ferroptosis after intracerebral hemorrhage.

OBJECTIVE: Neuronal precursor cells expressed developmentally down-regulated 4 (Nedd4) are believed to play a critical role in promoting the degradation of substrate proteins and are involved in numerous biological processes. However, the role of Nedd4 in intracerebral hemorrhage (ICH) remains unknown. This study aims to investigate the regulatory role of Nedd4 in the ICH model. METHODS: Male C57BL/6J mice were induced with ICH. Subsequently, the levels of glutathione peroxidase 4 (GPX4), malondialdehyde (MDA) concentration, iron content, mitochondrial morphology, as well as the expression of divalent metal transporter 1 (DMT1) and Nedd4 were assessed after ICH. Furthermore, the impact of Nedd4 overexpression was evaluated through analyses of hematoma area, ferroptosis, and neurobehavioral function. The mechanism underlying Nedd4-mediated degradation of DMT1 was elecidated using immunoprecipitation (IP) after ICH. RESULTS: Upon ICH, the level of DMT1 in the brain increased, but decreased when Nedd4 was overexpressed using Lentivirus, suggesting a negative correlation between Nedd4 and DMT1. Additionally, the degradation of DMT1 was inhibited after ICH. Furthermore, it was found that Nedd4 can interact with and ubiquitinate DMT1 at lysine residues 6, 69, and 277, facilitating the degradation of DMT1. Functional analysis indicated that overexpression of Nedd4 can alleviate ferroptosis and promote recovery following ICH. CONCLUSION: The results demonstrated that ferroptosis occurs via the Nedd4/DMT1 pathway during ICH, suggesting it potential as a valuable target to inhibit ferroptosis for the treatment of ICH.

Sandwich-type electrochemical aptasensor based on hemin-graphite oxide as a signal label and rGO/MWCNTs/chitosan/carbon quantum dot modified electrode for sensitive detection of Acinetobacter baumannii bacteria.

Acinetobacter baumannii (A. baumannii) is a pathogenic bacterium that causes severe infections and its rapid and reliable diagnosis is essential for effective control and treatment. In this study, we present an electrochemical aptasensor based on a signal amplification strategy for the detection of A. baumannii, the high specificity and affinity of the aptamer for the target make it favorable for signal amplification. This allows for a highly sensitive and selective detection of the target. The aptasensor is based on a carbon screen-printed electrode (CSPE) that has been modified with a nanocomposite consisting of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), chitosan (CS), and a synthesized carbon quantum dot (CQD) from CS. Additionally, the self-assembled aptamers were immobilized on hemin-graphite oxide (H-GO) as a signal probe. The composition of the nanocomposite (rGO-MWCNT/CS/CQD) provides high conductivity and stability, facilitating the efficient capture of A. baumannii onto the surface of the aptasensor. Also, aptamer immobilized on Hemin-graphite oxide (H-GO/Aptamer) was utilized as an electrochemical signal reporter probe by H reduction. This approach improved the detection sensitivity and the aptamer surface density for detecting A. baumannii. Furthermore, under optimized experimental conditions, the aptasensor was demonstrated to be capable of detecting A. baumannii with a linear range of (10 - 1 × 107 Colony-forming unit (CFU)/mL) and a limit of detection (LOD) of 1 CFU/mL (σ = 3). One of the key features of this aptasensor is its ability to distinguish between live and dead bacteria cells, which is very important and critical for clinical applications. In addition, we have successfully detected A. baumannii bacteria in healthy human serum and skim milk powder samples provided using the prepared electrochemical aptasensor. The functional groups present in the synthetic CQD, rGO-MWCNT, and chitosan facilitate biomolecule immobilization and enhance stability and activity. The fast electron-transfer kinetics and high conductivity of these materials contribute to improved sensitivity and selectivity. Furthermore, The H-GO/Aptamer composite's large surface area increases the number of immobilized secondary aptamers and enables a more stable structure. This large surface area also facilitates more H loading, leading to signal amplification.

Both hemoglobin and hemin cause damage to retinal pigment epithelium through the iron ion accumulation.

Subretinal hemorrhages result in poor vision and visual field defects. During hemorrhage, several potentially toxic substances are released from iron-based hemoglobin and hemin, inducing cellular damage, the detailed mechanisms of which remain unknown. We examined the effects of excess intracellular iron on retinal pigment epithelial (RPE) cells. A Fe2+ probe, SiRhoNox-1 was used to investigate Fe2+ accumulation after treatment with hemoglobin or hemin in the human RPE cell line ARPE-19. We also evaluated the production of reactive oxygen species (ROS) and lipid peroxidation. Furthermore, the protective effect of-an iron chelator, 2,2'-bipyridyl (BP), and ferrostatin-1 (Fer-1) on the cell damage, was evaluated. Fe2+ accumulation increased in the hemoglobin- or hemin-treated groups, as well as intracellular ROS production and lipid peroxidation. In contrast, BP treatment suppressed RPE cell death, ROS production, and lipid peroxidation. Pretreatment with Fer-1 ameliorated cell death in a concentration-dependent manner and suppressed ROS production and lipid peroxidation. Taken together, these findings indicate that hemoglobin and hemin, as well as subretinal hemorrhage, may induce RPE cell damage and visual dysfunction via intracellular iron accumulation.