Hemoglobin-Based Oxygen Carriers Incorporating Nanozymes for the Depletion of Reactive Oxygen Species

A novel PEG-mediated approach to entrap hemoglobin (Hb) within ZIF-8 nanoparticles: Balancing crystalline structure, Hb content and functionality

Hemoglobin (Hb)-based oxygen carriers are investigated as a potential alternative or supplement to regular blood transfusions, particularly in critical and life-threatening scenarios. These include situations like severe trauma in remote areas, battlefield conditions, instances where blood transfusion is not feasible due to compatibility concerns, or when patients decline transfusions based on religious beliefs. This study introduces a novel method utilizing poly(ethylene glycol) (PEG) to entrap Hb within ZIF-8 nanoparticles (i.e., Hb@ZIF-8 NPs). Through meticulous screening, we achieved Hb@ZIF-8 NPs with a record-high Hb concentration of 34 mg mL-1. These NPs, sized at 168 nm, displayed exceptional properties: a remarkable 95 % oxyhemoglobin content, excellent encapsulation efficiency of 85 %, and resistance to Hb oxidation into methemoglobin (metHb). The addition of PEG emerged as a crucial factor amplifying Hb entrapment within ZIF-8, especially at higher Hb concentrations, reaching an unprecedented 34 mg mL-1. Importantly, PEG exhibited a protective effect, preventing metHb conversion in Hb@ZIF-8 NPs at elevated Hb concentrations.

Nanomaterial-related hemoglobin-based oxygen carriers, with emphasis on liposome and nano-capsules, for biomedical applications: current status and future perspectives

Oxygen is necessary for life and plays a key pivotal in maintaining normal physiological functions and treat of diseases. Hemoglobin-based oxygen carriers (HBOCs) have been studied and developed as a replacement for red blood cells (RBCs) in oxygen transport due to their similar oxygen-carrying capacities. However, applications of HBOCs are hindered by vasoactivity, oxidative toxicity, and a relatively short circulatory half-life. With advancements in nanotechnology, Hb encapsulation, absorption, bioconjugation, entrapment, and attachment to nanomaterials have been used to prepare nanomaterial-related HBOCs to address these challenges and pend their application in several biomedical and therapeutic contexts. This review focuses on the progress of this class of nanomaterial-related HBOCs in the fields of hemorrhagic shock, ischemic stroke, cancer, and wound healing, and speculates on future research directions. The advancements in nanomaterial-related HBOCs are expected to lead significant breakthroughs in blood substitutes, enabling their widespread use in the treatment of clinical diseases.

Influence of different conjugation methods for activating antibodies on polymeric nanoparticles: Effects for polyclonal expansion of human CD8+ T cells

Particle-based systems have become a state-of-the-art method for in vitro expanding cytotoxic T cells by tailoring their surface with activating molecules. However, commonly used methods utilize facile carbodiimide chemistry leading to uncontrolled orientation of the immobilized antibodies on the particle surface that can lead to poor binding to target cells. To address this, selective coupling strategies utilizing regioselective chemical groups such as disulfide bridges offer a simple approach. In this work we present a set of methods to investigate the effect of polymeric nanoparticles, conjugated with either regioselective- or randomly-immobilized antiCD3 and antiCD28 antibodies, on the activation potential, expansion and expression of activation markers in T cells. We show that nanoparticles with well-oriented monovalent antibodies conjugated via maleimide require fewer ligands on the surface to efficiently expand T cells compared to bivalent antibodies randomly-immobilized via carbodiimide conjugation. Analysis of the T cell expression markers reveal that the T cell phenotype can be fine-tuned by adjusting the surface density of well-oriented antibodies, while randomly immobilized antibodies showed no differences despite their ligand density. Both conjugation techniques induced cytotoxic T cells, evidenced by analyzing their Granzyme B secretion. Furthermore, antibody orientation affects the immunological synapse and T cell activation by changing the calcium influx profile upon activation. Nanoparticles with well-oriented antibodies showed lower calcium influx compared to their bivalent randomly-immobilized counterparts. These results highlight the importance of controlling the antibody density and orientation on the nanoparticle surface via controlled coupling chemistries, helping to develop improved particle-based expansion protocols to enhance T cell therapies.

Development of novel polymer haemoglobin based particles as an antioxidant, antibacterial and an oxygen carrier agents

This innovative work aims to develop highly biocompatible and degradable nanoparticles by encapsulating haemoglobin (Hb) within poly-ε-caprolactone for novel biomedical applications. We used a modified double emulsion solvent evaporation method to fabricate the particles. A Scanning electron microscope (SEM) characterized them for surface morphology. Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-visible spectroscopies (UV-visible) elucidated preserved chemical and biological structure of encapsulated haemoglobin. The airproof equilibrium apparatus obtained the oxygen-carrying capacity and P50 values. The DPPH assay assessed free radical scavenging potential. The antibacterial properties were observed using four different bacterial strains by disk diffusion method. The MTT assay investigates the cytotoxic effects on mouse fibroblast cultured cell lines (L-929). The MTT assay showed that nanoparticles have no toxicity over large concentrations. The well-preserved structure of Hb within particles, no toxicity, high oxygen affinity, P50 value, and IC50 values open the area of new research, which may be used as artificial oxygen carriers, antioxidant, and antibacterial agents, potential therapeutic agents as well as drug carrier particles to treat the cancerous cells. The novelty of this work is the antioxidant and antibacterial properties of developed nanoparticles are not been reported yet. Results showed that the prepared particles have strong antioxidant and antibacterial potential.

Gas Therapy: Generating, Delivery, and Biomedical Applications

Oxygen (O2 ), nitric oxide (NO), carbon monoxide (CO), hydrogen sulfide (H2 S), and hydrogen (H2 ) with direct effects, and carbon dioxide (CO2 ) with complementary effects on the condition of various diseases are known as therapeutic gases. The targeted delivery and in situ generation of these therapeutic gases with controllable release at the site of disease has attracted attention to avoid the risk of gas poisoning and improve their performance in treating various diseases such as cancer therapy, cardiovascular therapy, bone tissue engineering, and wound healing. Stimuli-responsive gas-generating sources and delivery systems based on biomaterials that enable on-demand and controllable release are promising approaches for precise gas therapy. This work highlights current advances in the design and development of new approaches and systems to generate and deliver therapeutic gases at the site of disease with on-demand release behavior. The performance of the delivered gases in various biomedical applications is then discussed.

Synthesis of bioactive hemoglobin-based oxygen carrier nanoparticles via metal-phenolic complexation

The transfusion of donor red blood cells (RBCs) is seriously hampered by important drawbacks that include limited availability and portability, the requirement of being stored in refrigerated conditions, a short shelf life or the need for RBC group typing and crossmatching. Thus, hemoglobin (Hb)-based oxygen (O2) carriers (HBOCs) which make use of the main component of RBCs and the responsible protein for O2 transport, hold a lot of promise in modern transfusion and emergency medicine. Despite the great progress achieved, it is still difficult to create HBOCs with a high Hb content to attain the high O2 demands of our body. Herein a metal-phenolic self-assembly approach that can be conducted in water and in one step to prepare nanoparticles (NPs) fully made of Hb (Hb-NPs) is presented. In particular, by combining Hb with polyethylene glycol, tannic acid (TA) and manganese ions, spherical Hb-NPs with a uniform size around 350-525 nm are obtained. The functionality of the Hb-NPs is preserved as shown by their ability to bind and release O2 over multiple rounds. The binding mechanism of TA and Hb is thoroughly investigated by UV-vis absorption and fluorescence spectroscopy. The binding site number, apparent binding constant at two different temperatures and the corresponding thermodynamic parameters are identified. The results demonstrate that the TA-Hb interaction takes place through a static mechanism in a spontaneous process as shown by the decrease in Gibbs free energy. The associated increase in entropy suggests that the TA-Hb binding is dominated by hydrophobic interactions.

Structural and functional alterations of polydopamine-coated hemoglobin: New insights for the development of successful oxygen carriers

One of the major factors that is currently hindering the development of hemoglobin (Hb)-based oxygen carriers (HBOCs) is the autoxidation of Hb into nonfunctional methemoglobin. Modification with polydopamine (PDA), which is a biocompatible free radical scavenger has shown the ability to protect Hb against oxidation. Due to its tremendous potential in the development of successful HBOCs, herein, we conduct a thorough evaluation of the effect of PDA on the stability, aggregation, structure and function of the underlying Hb. By UV-vis spectrometry we show that PDA can prevent Hb's aggregation while thermal denaturation studies indicate that, although PDA coating resulted in a lower midpoint transition temperature, it was also able to protect the protein from full denaturation. These results are further corroborated by differential scanning calorimetry. Circular dichroism reveals that PDA can promote changes in Hb's secondary structure while, by UV-vis spectroscopy, we show that PDA also interacts with the porphyrin complex located in Hb's hydrophobic pocket. Last but not least, affinity studies show that PDA-coated Hb has a higher capability for oxygen release. Such an effect is further enhanced at lower pH. Importantly, through molecular docking simulations we provide a plausible explanation for the observed experimental results.

PEG-conjugated bovine haemoglobin enhances efficiency of chemotherapeutic agent doxorubicin with alleviating DOX-induced splenocardiac toxicity in the breast cancer

Doxorubicin (DOX) is an effective chemotherapeutic agent widely used for cancer treatment. However, hypoxia in tumour tissue and obvious adverse effects particularly cardiotoxicity restricts the clinical usage of DOX. Our study is based on the co-administration of haemoglobin-based oxygen carriers (HBOCs) and DOX in a breast cancer model to investigate HBOCs' ability to enhance chemotherapeutic effectiveness and its capabilities to alleviate the side effects induced by DOX. In an in-vitro study, the results suggested the cytotoxicity of DOX was significantly improved when combined with HBOCs in a hypoxic environment, and produced more γ-H2AX indicating higher DNA damage than free DOX did. Compared with administration of free DOX, combined therapy exhibited a stronger tumour suppressive effect in an in-vivo study. Further mechanism studies showed that the expression of various proteins such as hypoxia-inducible factor-1α (HIF-1α), CD31, CD34, and vascular endothelial growth factor (VEGF) in tumour tissues was also significantly reduced in the combined treatment group. In addition, HBOCs can significantly reduce the splenocardiac toxicity induced by DOX, according to the results of the haematoxylin and eosin (H&E) staining and histological investigation. This study suggested that PEG-conjugated bovine haemoglobin may not only reduce the hypoxia in tumours and increase the efficiency of chemotherapeutic agent DOX, but also alleviate the irreversible heart toxicity caused by DOX-inducted splenocardiac dysregulation.

Structural optimization and prospect of constructing hemoglobin oxygen carriers based on hemoglobin

The current global shortage of organ resources, the imbalance in donor-recipient demand and the increasing number of high-risk donors make organ preservation a necessity to consider appropriate storage options. The current method of use often has risks such as blood group mismatch, short shelf life, and susceptibility. HBOCs have positive effects such as anti-apoptotic, anti-inflammatory, antioxidant and anti-proliferative, which have significant advantages in organ storage. Therefore, it is the common pursuit of researchers to design and synthesize HBOCs with safety, ideal oxygen-carrying capacity, easy storage, etc. that are widely applicable and optimal for different organs. There has been a recent advancement in understanding HBOCs mechanisms, which is discussed in this review.

Poly(2-ethyl-2-oxazoline)-Conjugated Hemoglobins as a Red Blood Cell Substitute

Hemoglobin wrapped covalently with poly(2-ethyl-2-oxazoline)s (POx-Hb) is characterized physicochemically and physiologically as an artificial O2 carrier for use as a red blood cell (RBC) substitute. The POx-Hb is generated by linkage of porcine Hb surface-lysines to a sulfhydryl terminus of the POx derivative, with the average binding number of the polymers ascertained as 6. The POx-Hb shows moderately higher colloid osmotic activity and O2 affinity than the naked Hb. Human adult HbA conjugated with POx also possesses equivalent features and O2 binding properties. The POx-Hb solution exhibits good hemocompatibility, with no influence on the functions of platelets, granulocytes, and monocytes. Its circulation half-life in rats is 14 times longer than that of naked Hb. Hemorrhagic shock in rats is relieved sufficiently by infusion of the POx-Hb solution, as revealed by improvements of circulatory parameters. Serum biochemistry tests and histopathological observations indicate no acute toxicity or abnormality in the related organs. All results indicate that POx-Hb represents an attractive alternative for RBCs and a useful O2 therapeutic reagent in transfusion medicine.

Hemoglobin-stabilized gold nanoclusters displaying oxygen transport ability, self-antioxidation, auto-fluorescence properties and long-term storage potential

The development of hemoglobin (Hb)-based oxygen carriers (HBOCs) holds a lot of potential to overcome important drawbacks of donor blood such as a short shelf life or the potential risk of infection. However, a crucial limitation of current HBOCs is the autoxidation of Hb into methemoglobin (metHb), which lacks oxygen-carrying capacity. Herein, we address this challenge by fabricating a Hb and gold nanoclusters (AuNCs) composite (Hb@AuNCs) which preserves the exceptional features of both systems. Specifically, the Hb@AuNCs retain the oxygen-transporting properties of Hb, while the AuNCs provide antioxidant functionality as shown by their ability to catalytically deplete harmful reactive oxygen species (ROS). Importantly, these ROS-scavenging properties translate into antioxidant protection by minimizing the autoxidation of Hb into non-functional metHb. Furthermore, the AuNCs render Hb@AuNCs with auto-fluorescence properties which could potentially allow them to be monitored once administered into the body. Last but not least, these three features (i.e., oxygen transport, antioxidant and fluorescence properties) are well maintained following storage as a freeze-dried product. Thus, overall, the as-prepared Hb@AuNCs hold the potential to be used as a multifunctional blood surrogate in the near future.

Metal-organic framework-based oxygen carriers with antioxidant activity resulting from the incorporation of gold nanozymes

Blood transfusions are a life-saving procedure since they can preserve the body's oxygen levels in patients suffering from acute trauma, undergoing surgery, receiving chemotherapy or affected by severe blood disorders. Due to the central role of hemoglobin (Hb) in oxygen transport, so-called Hb-based oxygen carriers (HBOCs) are currently being developed for situations where donor blood is not available. In this context, an important challenge that needs to be addressed is the oxidation of Hb into methemoglobin (metHb), which is unable to bind and release oxygen. While several research groups have considered the incorporation of antioxidant enzymes to create HBOCs with minimal metHb conversion, the use of biological enzymes has important limitations related to their high cost, potential immunogenicity or low stability in vivo. Thus, nanomaterials with enzyme-like properties (i.e., nanozymes (NZs)) have emerged as a promising alternative. Amongst the different NZs, gold (Au)-based metallic nanoparticles are widely used for biomedical applications due to their biocompatibility and multi-enzyme mimicking abilities. Thus, in this work, we incorporate Au-based NZs into a type of HBOC previously reported by our group (i.e., Hb-loaded metal-organic framework (MOF)-based nanocarriers (NCs)) and investigate their antioxidant properties. Specifically, we prepare MOF-NCs loaded with Au-based NZs and demonstrate their ability to catalytically deplete over multiple rounds of two prominent reactive oxygen species (ROS) that exacerbate Hb's autoxidation (i.e., hydrogen peroxide and the superoxide radical). Importantly, following loading with Hb, we show how these ROS-scavenging properties translate into a decrease in metHb content. All in all, these results highlight the potential of NZs to create novel HBOCs with antioxidant protection which may find applications as a blood substitute in the future.

Manipulate tumor hypoxia for improved photodynamic therapy using nanomaterials

Due to its low adverse effects, minimal invasiveness, and outstanding patient compliance, photodynamic therapy (PDT) has drawn a great deal of interest, which is achieved through incomplete reduction of O₂ by a photosensitizer under light illumination that produces amounts of reactive oxygen species (ROS). However, tumor hypoxia significantly hinders the therapeutic effect of PDT so that tumor cells cannot be eliminated, which results in tumor cells proliferating, invading, and metastasizing. Additionally, O₂ consumption during PDT exacerbates hypoxia in tumors, leading to several adverse events after PDT treatment. In recent years, various investigations have focused on conquering or using tumor hypoxia by nanomaterials to amplify PDT efficacy, which is summarized in this review. This comprehensive review's objective is to present novel viewpoints on the advancement of oxygenation nanomaterials in this promising field, which is motivated by hypoxia-associated anti-tumor therapy.

Erythrocyte-Inspired Functional Materials for Biomedical Applications

Erythrocytes are the most abundant cells in the blood. As the results of long-term natural selection, their specific biconcave discoid morphology and cellular composition are responsible for gaining excellent biological performance. Inspired by the intrinsic features of erythrocytes, various artificial biomaterials emerge and find broad prospects in biomedical applications such as therapeutic delivery, bioimaging, and tissue engineering. Here, a comprehensive review from the fabrication to the applications of erythrocyte-inspired functional materials is given. After summarizing the biomaterials mimicking the biological functions of erythrocytes, the synthesis strategies of particles with erythrocyte-inspired morphologies are presented. The emphasis is on practical biomedical applications of these bioinspired functional materials. The perspectives for the future possibilities of the advanced erythrocyte-inspired biomaterials are also discussed. It is hoped that the summary of existing studies can inspire researchers to develop novel biomaterials; thus, accelerating the progress of these biomaterials toward clinical biomedical applications.

Tumor-penetrating nanoplatform with ultrasound "unlocking" for cascade synergistic therapy and visual feedback under hypoxia

BACKGROUND

Combined therapy based on the effects of cascade reactions of nanoplatforms to combat specific solid tumor microenvironments is considered a cancer treatment strategy with transformative clinical value. Unfortunately, an insufficient O₂ supply and the lack of a visual indication hinder further applications of most nanoplatforms for solid tumor therapy.

RESULTS

A visualizable nanoplatform of liposome nanoparticles loaded with GOD, H(Gd), and PFP and grafted with the peptide tLyP-1, named _tLyP-1H(Gd)-GOD@PFP, was constructed. The double-domain peptide tLyP-1 was used to specifically target and penetrate the tumor cells; then, US imaging, starvation therapy and sonodynamic therapy (SDT) were then achieved by the ultrasound (US)-activated cavitation effect under the guidance of MR/PA imaging. GOD not only deprived the glucose for starvation therapy but also produced H₂O₂, which in coordination with ¹O₂ produced by H(Gd), enable the effects of SDT to achieve a synergistic therapeutic effect. Moreover, the synergistic therapy was enhanced by O₂ from PFP and low-intensity focused ultrasound (LIFU)-accelerated redox effects of the GOD. The present study demonstrated that the nanoplatform could generate a 3.3-fold increase in ROS, produce a 1.5-fold increase in the maximum rate of redox reactions and a 2.3-fold increase in the O₂ supply in vitro, and achieve significant tumor inhibition in vivo.

CONCLUSION

We present a visualizable nanoplatform with tumor-penetrating ability that can be unlocked by US to overcome the current treatment problems by improving the controllability of the O₂ supply, which ultimately synergistically enhanced cascade therapy.

ROS generation strategy based on biomimetic nanosheets by self-assembly of nanozymes

Reactive oxygen species (ROS) play an important role in physiology and have been applied in tumor therapy. However, insufficient endogenous H₂O₂ and hypoxia in cancer cells can lead to limited ROS production and poor therapeutic efficacy. Herein, we develop a biomimetic nanosheet material based on the self-assembly of nanozymes that could supply H₂O₂ under acidic conditions and catalyze a cascade of intracellular biochemical reactions to produce ROS under both normoxic and hypoxic conditions without any external stimuli. In this system, the copper peroxide nanosheets (CPNS), which are pH-responsive, were prepared through coordination of H₂O₂ to Cu²⁺ and then modified using ultrafine Pt NPs to form CPNS@Pt. The CPNS could decompose under acidic conditions, allowing the simultaneous release of Fenton catalytic Cu²⁺ and H₂O₂ accompanied by a Fenton-type reaction between them. On the other hand, Pt NPs were also released. The released Pt NPs behave as an oxidase mimic and catalase mimic. In this way, the well-defined CPNS@Pt can not only relieve hypoxic conditions but also generate ROS to induce cell apoptosis, thereby paving the way for the development of a nanozyme with multienzyme activity as a therapeutic strategy.

Highly sensitive and low-power consumption metalloporphyrin-based junctions for COx detection with excellent recovery

The development of cost-effective and eco-friendly sensor materials is needed to realize the application of detectors in daily life-such as in the internet of things. In this regard, monitoring air pollutants such as carbon monoxide (CO) and carbon dioxide (CO₂), mainly emitted by anthropogenic sources from daily human activities, is of great importance. In particular, developing a susceptible and portable CO₂ sensor raises a dilemma because of the chemical inertness and non-polarity of CO₂ molecules. We find that porphyrin-based materials, exploited by nature in biological systems, are a playground to search for such sensor materials. Using density functional non-equilibrium Green's function formalism, we fully screen all 3d metalloporphyrin (MPor) based devices to find efficient CO and CO₂ gas sensors. Our detailed analysis of the adsorption energy, molecular orbitals, transmission spectra, sensitivity, and recovery time reveals that the nature of central M alters the efficiency of MPor gas detectors. We find that CO and CO₂ can be monitored using, respectively, CoPor- and TiPor-based devices. The estimated sensitivity is around 100%, along with a fast recovery time at very low bias voltages (V ≥ 0.5 V), which turn metalloporphyrins into promising candidates for the widespread development of enhanced CO and CO₂ sensors awaiting further experimental validations.

Ultrasmall Antioxidant Cerium Oxide Nanoparticles for Regulation of Acute Inflammation

Cerium oxide nanoparticles (CeONP), having potent antioxidant properties, are highly promising nanomaterials for treatment of diseases in which oxidative stress from excessive reactive oxygen species (ROS) plays a critical role in the pathogenesis and progression. However, most previously reported CeONP formulations were not efficiently cleared from the body, precluding their clinical translation. Herein, we report ultrasmall CeONP that can mitigate activation of macrophages and subsequent acute inflammation. It is found that these CeONP can effectively scavenge reactive species, inhibit macrophage activation, and minimize their recruitment and infiltration to the inflammation site, which lead to alleviation of edema and pain hypersensitivity. Moreover, we demonstrate that CeONP can be effectively excreted from the body within 24 h of systemic administration, minimizing long-term toxicity concerns. Altogether, our findings suggest that CeONP may be explored as both antioxidant and anti-inflammatory agents that can reduce acute inflammation with a better safety profile than existing nanoparticles.

Optimization of Hemoglobin Encapsulation within PLGA Nanoparticles and Their Investigation as Potential Oxygen Carriers

Hemoglobin (Hb)-based oxygen carriers (HBOCs) display the excellent oxygen-carrying properties of red blood cells, while overcoming some of the limitations of donor blood. Various encapsulation platforms have been explored to prepare HBOCs which aim to avoid or minimize the adverse effects caused by the administration of free Hb. Herein, we entrapped Hb within a poly(lactide-co-glycolide) (PLGA) core, prepared by the double emulsion solvent evaporation method. We study the effect of the concentrations of Hb, PLGA, and emulsifier on the size, polydispersity (PDI), loading capacity (LC), and entrapment efficiency (EE) of the resulting Hb-loaded PLGA nanoparticles (HbNPs). Next, the ability of the HbNPs to reversibly bind and release oxygen was thoroughly evaluated. When needed, trehalose, a well-known protein stabilizer that has never been explored for the fabrication of HBOCs, was incorporated to preserve Hb's functionality. The optimized formulation had a size of 344 nm, a PDI of 0.172, a LC of 26.9%, and an EE of 40.7%. The HbNPs were imaged by microscopy and were further characterized by FTIR and CD spectroscopy to assess their chemical composition and structure. Finally, the ability of the encapsulated Hb to bind and release oxygen over several rounds was demonstrated, showing the preservation of its functionality.

Metal-organic framework-based oxygen carriers with antioxidant protection as a result of a polydopamine coating

Rapid haemorrhage control to restore tissue oxygenation is essential in order to improve survival following traumatic injury. To this end, the current clinical standard relies on the timely administration of donor blood. However, limited availability and portability, special storage requirements, the need for blood type matching and risks of disease transmission result in severe logistical challenges, impeding the use of donor blood in pre-hospital scenarios. Therefore, great effort has been devoted to the development of haemoglobin (Hb)-based oxygen carriers (HBOCs), which could be used as a "bridge" to maintain tissue oxygenation until hospital admission. HBOCs hold the potential to diminish the deleterious effects of acute bleeding and associated mortality rates. We recently presented a novel HBOC, consisting of Hb-loaded metal organic framework (MOF)-based nanoparticles (NPs) (MOF^Hb-NPs), and demonstrated its ability to reversibly bind and release oxygen. However, a long standing challenge when developing HBOCs is that, over time, Hb oxidizes to non-functional methaemoglobin (metHb). Herein, we address this challenge by modifying the surface of the as-prepared MOF^Hb-NPs with an antioxidant polydopamine (PDA) coating. The conditions promoting the greatest PDA deposition are first optimized. Next, the ability of the resulting PDA-coated MOF^Hb-NPs to scavenge important reactive oxygen species is demonstrated both in a test tube and in the presence of two relevant cell lines (i.e., macrophages and endothelial cells). Importantly, this antioxidant protection translates into minimal metHb conversion.

Synthesis of Nanoparticles Fully Made of Hemoglobin with Antioxidant Properties: A Step toward the Creation of Successful Oxygen Carriers

Transfusion of donor red blood cells (RBCs) is a crucial and widely employed clinical procedure. However, important constraints of blood transfusions include the limited availability of blood, the need for typing and cross-matching due to the RBC membrane antigens, the limited storage lifetime, or the risk for disease transmission. Hence, a lot of effort has been devoted to develop RBC substitutes, which are free from the limitations of donor blood. Despite the potential, the creation of hemoglobin (Hb)-based oxygen carriers is still facing important challenges. To allow for proper tissue oxygenation, it is essential to develop carriers with high Hb loading since Hb comprises about 96% of the RBCs' dry weight. In this work, nanoparticles (NPs) fully made of Hb are prepared by the desolvation precipitation method. Several parameters are screened (i.e., Hb concentration, desolvation ratio, time, and sonication intensity) to finally obtain Hb-NPs with a diameter of ∼568 nm and a polydispersity index (PDI) of 0.2. A polydopamine (PDA) coating is adsorbed to prevent the disintegration of the resulting Hb/PDA-NPs. Due to the antioxidant character of PDA, the Hb/PDA-NPs are able to deplete two harmful reactive oxygen species, namely, the superoxide radical anion and hydrogen peroxide. Such antioxidant protection also translates into minimizing the oxidation of the entrapped Hb to nonfunctional methemoglobin (metHb). This is a crucial aspect since metHb conversion also results in inflammatory reactions and dysregulated vascular tone. Finally, yet importantly, the reported Hb/PDA-NPs are also both hemo- and biocompatible and preserve the reversible oxygen-binding and releasing properties of Hb.

Nanostructured Ceria: Biomolecular Templates and (Bio)applications

Ceria (CeO2) nanostructures are well-known in catalysis for energy and environmental preservation and remediation. Recently, they have also been gaining momentum for biological applications in virtue of their unique redox properties that make them antioxidant or pro-oxidant, depending on the experimental conditions and ceria nanomorphology. In particular, interest has grown in the use of biotemplates to exert control over ceria morphology and reactivity. However, only a handful of reports exist on the use of specific biomolecules to template ceria nucleation and growth into defined nanostructures. This review focusses on the latest advancements in the area of biomolecular templates for ceria nanostructures and existing opportunities for their (bio)applications.

Translational research of hemoglobin vesicles as a transfusion alternative

Clinical situations arise in which blood for transfusion becomes scarce or unavailable. Considerable demand for a transfusion alternative persists because of various difficulties posed by blood donation and transfusion systems. Hemoglobin-vesicles (HbV) are artificial oxygen carriers being developed for use as a transfusion alternative. Just as biomembranes of red blood cells (RBCs) do, phospholipid vesicles (liposomes) for Hb encapsulation can protect the human body from toxic effects of molecular Hb. The main HbV component, Hb, is obtained from discarded human donated blood. Therefore, HbV can be categorized as a biologic agent targeting oxygen for peripheral tissues. The purification procedure strictly eliminates the possibility of viral contamination. It also removes all concomitant unstable enzymes present in RBC for utmost safety from infection. The deoxygenated HbVs, which are storable for over years at ambient temperature, can function as an alternative to blood transfusion for resuscitation from hemorrhagic shock and O₂ therapeutics. Moreover, a recent study clarified beneficial effects for anti-oxidation and anti-inflammation by carbon monoxide (CO)-bound HbVs. Autoxidation of HbV (HbO₂ → metHb + O₂-.) is unavoidable after intravenous administration. Co-injection of methylene blue can extract the intraerythrocytic glycolytic electron energy effectively and reduce metHb. Other phenothiazine dyes can also function as electron mediators to improve the functional life span of HbV. This review paper summarizes recent progress of the research and development of HbV, aimed at clinical applications.