Hong Zhou

Drug-resistant bacterium-infected wounds pose a serious clinical challenge, underscoring the need for therapeutic materials that respond to dynamic healing stages. Herein, we report a sequential multimodal platform embedding a self-adaptive IrPtCu nanozyme into a madecassoside-enriched hyaluronic acid hydrogel (HIPCM) for rapid bacterial eradication and accelerated wound healing. Leveraging trimetallic synergy and pH-adaptive reactive oxygen species (ROS) regulation, IrPtCu nanozyme exhibits strong oxidase, peroxidase, glutathione oxidase, and glutathione peroxidase-like activities, enabling efficient ROS generation and potent antibacterial performance. After disinfection, it switches to ROS scavenging through superoxide dismutase and catalase-like cascades, alleviating oxidative stress and cooperating with madecassoside to promote tissue repair. In a methicillin-resistant Staphylococcus aureus ( MRSA )-infected mouse model, HIPCM demonstrates strong antibacterial efficacy, promotes M2 macrophage polarization and angiogenesis, and accelerates high-quality repair. Preclinical studies in Bama mini-pigs further confirm improved collagen deposition, hair follicle regeneration, and functional restoration. This work offers a comprehensive strategy integrating adaptive nanozymes and natural herbal medicines for treating drug-resistant wounds.

Hemocompatibility is critical for intravenous hemoglobin-based oxygen carriers (HBOCs). We evaluated the hemocompatibility of polyethylene glycol-conjugated bovine hemoglobin (PEG-bHb) to facilitate its optimization and clinical translation. PEG-bHb was synthesized and characterized. In vitro hemocompatibility was assessed by incubating blood components with PEG-bHb (2.5–40 mg/mL), evaluating erythrocyte morphology/function, coagulation, complement activation, and leu kocyte phagocytosis. In vivo assessments in Wistar rats injecting PEG-bHb (50–100 mg/kg) included erythrocyte function, coagulation, complement activation, and histopathology. PEG-bHb exhibited increased hydrodynamic diameter, unaltered zeta potential, elevated colloidal osmotic pressure (COP) and viscosity, alongside a decreased P₅₀ versus bovine hemoglobin (bHb). In vitro, PEG-bHb preserved erythrocyte morphology without inducing eryptosis, and oxygen supply efficiency was unaffected. Moreover, it slightly disrupted the activated partial thromboplastin time (APTT), the thrombin time (TT), and the platelet adhesion, while platelet activation and thromboelastography (TEG) remained unchanged. PEG-bHb did not activate complement and only mildly enhanced phagocytosis at 2.5 mg/mL. In vivo, PEG-bHb did not affect eryptosis, oxygen supply efficiency, coagulation, complement activation, and no inflammatory infiltration was observed. PEG-bHb maintains erythrocyte morphology and function, slightly perturb coagulation without compromising immunocompatibility, and demonstrated excellent hemocompatibility.

Hemolysis rate is usually used as the acceptance criterion for stored red blood cells (RBCs) in clinical practice. However, there is a current lack of parameters for the characterization of hemoglobin quality. This study aimed to incorporate oxygen affinity, cooperativity, and the Bohr effect into a parameter system to monitor oxygen supply efficiency in stored RBCs, potentially serving as a basis for quality assessment. Han Chinese blood from plains, Tibetan blood from plateau, bovine hemoglobin (bHb), and a dextran–bovine hemoglobin conjugate (Dex20-bHb) were analyzed using the BLOODOX-2018. Oxygen affinity (P₅₀) was determined by oxygen dissociation curves (ODCs) at pH = 7.4. Cooperativity was assessed through the Hill coefficient, calculated from the fitting range of the Hill equation. The Bohr effect was evaluated by the acid-base sensitivity index (SI) under simulated pH conditions of the lungs (pH = 7.6) and tissues (pH = 7.2) to calculate corresponding P₅₀ values. Oxygen partial pressures (PO₂) simulating lungs (PO₂ = 100 mmHg for plains and 60 mmHg for plateau) and tissues (PO₂ = 40 mmHg for plains and 30 mmHg for plateau) were used to calculate theoretical oxygen-release capacities in both environments. Multiple regression analysis explored relationships among parameters, constructing a system to assess changes in rat RBCs during storage. Optimized test methods determined P₅₀, Hill coefficient, SI, and theoretical oxygen-release capacities for Han Chinese blood, Tibetan blood, bHb, and Dex20-bHb samples in various environments. We constructed a parameter system to characterize blood’s oxygen supply efficiency, revealing the significant influence of the Bohr effect. This influence varied with environmental changes in oxygen affinity. We validated the system using stored rat RBCs, finding consistent P₅₀ trends with predictions, and initial increases in Hill coefficient and SI followed by decreases. Theoretical oxygen-release capacities varied significantly between plateau and plain environments. These results support using oxygen supply efficiency to assess RBC storage quality for developing transfusion strategies. P₅₀, Hill coefficient, SI, and theoretical oxygen-release capacity in different environments can be incorporated into blood oxygen supply efficiency characterization systems to assess the quality changes in RBCs during storage.

One of the major factors currently hindering the development of hemoglobin-based oxygen carriers (HBOCs) is the autoxidation of hemoglobin to inactive methemoglobin (MetHb). The effects of spermine on the stability, aggregation, structure, and function of adult hemoglobin (HbA) were studied. The interaction of spermine with HbA was elucidated by dynamic light scattering, colloid osmotic pressure measurements, thermal denaturation analysis, static light scattering, and oxygen dissociation assay. The antioxidant capacity of spermine was confirmed through UV–vis spectroscopic recordings, calculations of MetHb formation, and hydroxyl radical scavenging. The P50 value was determined by the oxygen dissociation curve to investigate the roles of spermine in increasing HbA’s oxygen affinity. The pH-dependent affinity between spermine and HbA was validated through surface plasmon resonance experiments. The transformation of HbA’s partial α-helix to a β-sheet structure induced by spermine was clarified using a microfluidic modulation spectrometer. The binding of spermine to βASP99, βGLU101, αTHR38, and αASN97 on HbA and the conformational shift in HbA towards the ‘R’ state were investigated via molecular docking and molecular dynamics simulations. In a word, spermine can enhance the oxygen affinity of HbA, effectively reduce autoxidation, and hold promise for applications in the research of HBOCs or hemoglobin modification.

Objective: As the amount of hemoglobin (Hb) decreases during moderate acute normovolemic hemodilution (ANH), it is unclear whether the Hb-oxygen affinity (HOA) changes accordingly. Thus, this study aimed to explore changes in HOA during moderate ANH. Methods: A moderate ANH model of canine was established. Hemodynamic, blood gas, biochemical, oxygenation, and HOA-related parameters were measured. P ₅₀ was obtained using three methods. One was derived from the oxygen dissociation curve (ODC) by the Bloodox-2018 analyzer, and the other two were based on blood gas analyzers. Results: With decreased Hb and hematocrit (HCT) levels during ANH, the temperature (T) and base excess (BE) decreased, while Cl^– increased. Compared with baseline (BL), in hemodilution 1 (HCT decreased to 75% of the BL, H1) and hemodilution 2 (HCT decreased to 50% of the BL, H2), pH and HCO₃ ^– decreased. Methemoglobin (MetHb) levels in H2 were significantly higher than those in BL and H1. HOA-related parameters did not change significantly in moderate ANH. Factors that increase or decrease the P ₅₀ offset each other, leaving the P ₅₀ unchanged in moderate ANH. The P ₅₀ obtained based on the two blood gas analyzers was consistent, but neither was consistent with P ₅₀ derived from the ODC.

Hemoglobin oxygen affinity (HOA) increases during the storage of red blood cells (RBCs), which hinders the oxygen-release efficacy after transfusion. RBCs stored in alkaline preservation solution promote glycolysis and its final product lactate, which is an allosteric regulator of HOA. In recent years, lactylation has been widely studied, and the degree of lactylation is positively associated with the lactate concentration. However, it is unclear whether lactate can participate in the allosteric regulation of HOA via lactylation when lactate accumulates to a certain level during RBC storage in alkaline preservation solutions. Therefore, we prepared preservation solutions with the same formulation but different pH values and investigated the changes in P₅₀, which represent HOA, and lactate levels. We also performed comprehensive analysis on the lactylation of stored RBCs via molecular dynamics simulation and confirmed the effects of lactylation on hemoglobin (Hb) via in vitro experiments. We found lactylation modifications in RBCs and less storage damage when stored in alkaline preservation solutions. Lactylation acts predominantly on the lysine 66 site of the Hb β-subunit. Lactylation promotes conformational changes of Hb from the relaxed (R) state to the tight (T) state, which in turn promotes oxygen release from RBCs.

Myocardial infarction (MI) poses a serious threat to human health. MI induces oxidative damage and inflammation, leading to myocardial death, scarring, and ventricular remodeling. Nanozymes have shown potential to alleviate reactive oxygen species (ROS)-induced damage and treat cardiovascular diseases. In this study, we developed an ultrasmall PtIr bimetallic nanozyme to treat MI. The PtIr nanozyme exhibited robust superoxide dismutase- and catalase-mimicking catalytic activities, modulating the conversion of excessive ROS into harmless products. Furthermore, PtIr nanozyme treatment reduced ROS levels and apoptosis in human cardiomyocyte AC16 cells under oxidative stress in vitro, while increasing the expression of cardiomyocyte-related functional genes, including cTnT, cTnI, Cx43, and ACTN2. It also maintained the intracellular mitochondrial membrane potential, increased mitochondrial activity, and protected mitochondrial structure. In a rat MI model, the PtIr nanozyme attenuated neutrophil extracellular trap formation, apoptosis, and inflammation in the infarcted heart 1 week postadministration. Four weeks postadministration, the PtIr nanozyme significantly enhanced cardiomyocyte activity and functional connectivity, reduced infarct size and fibrosis levels, and increased microvascular density compared with phosphate-buffered saline or Ir nanozyme treatment. Proteomic analysis revealed that proteins associated with energy metabolism, mitochondrial function, and myocardial contraction were upregulated, while multiple pathways related to mitochondrial function and energy metabolism, such as fatty acid β-oxidation and the citric acid cycle, were enriched in the PtIr nanozyme injection group. These results suggest that the PtIr nanozyme remodels the infarct microenvironment by modulating mitochondrial function and the inflammatory response, repairing the damaged myocardium, and improving cardiac function. Our findings highlight a promising therapeutic strategy for MI.

Aging is an inevitable multifactor process that causes a decline in organ function and increases the risk of age-related diseases and death. Thus, the development of highly effective and safe therapeutic strategies to delay aging and age-related diseases is urgently required. In this study, we isolated natural melanin nanozymes (NMNs) from the ink sacs of live octopuses. The NMNs exhibited excellent superoxide-dismutase-mimicking and radical scavenging activities. In SAMP8 mice, treatment with NMNs improved their cognition and memory functions while restoring their aging-impaired liver function and lipid metabolism, thereby prolonging their lifespan. Moreover, the NMNs reversed metabolic changes in their aged brains and reconstructed their gut microbiota composition by enhancing microbial community diversity. Our findings indicate that NMNs treatment could be a promising approach for delaying aging and preventing age-associated physiological decline in humans.