Perfluorocarbon-based oxygen carriers: from physics to physiology

OMX: A NOVEL OXYGEN DELIVERY BIOTHERAPEUTIC IMPROVES OUTCOMES IN AN OVINE MODEL OF CONTROLLED HEMORRHAGIC SHOCK

ABSTRACT

Hemorrhagic shock is a major source of morbidity and mortality worldwide. While whole blood or blood product transfusion is a first-line treatment, maintaining robust supplies presents significant logistical challenges, particularly in austere environments. OMX is a novel nonhemoglobin (Hb)-based oxygen carrier derived from the H-NOX (heme-nitric oxide/oxygen binding) protein family. Because of their engineered oxygen (O 2 ) affinities, OMX proteins only deliver O 2 to severely hypoxic tissues. Additionally, unlike Hb-based oxygen carriers, OMX proteins do not scavenge nitric oxide in the vasculature. To determine the safety and efficacy of OMX in supporting tissue oxygen delivery and cardiovascular function in a large animal model of controlled hemorrhage, 2-3-week-old lambs were anesthetized, intubated, and mechanically ventilated. Hypovolemic shock was induced by acute hemorrhage to obtain a 50% reduction over 30 min. Vehicle (n = 16) or 400 mg/kg OMX (n = 13) treatment was administered over 15 min. Hemodynamics, arterial blood gases, and laboratory values were monitored throughout the 6-h study. Comparisons between groups were made using t tests, Wilcoxon rank sum test, and Fisher's exact test. Survival was assessed using Kaplan-Meier curves and the log-rank test. We found that OMX was well-tolerated and significantly improved lactate and base deficit trends, and hemodynamic indices ( P < 0.05). Median survival time was greater in the OMX-treated group (4.7 vs. 6.0 h, P < 0.003), and overall survival was significantly increased in the OMX-treated group (25% vs. 85%, P = 0.004). We conclude that OMX is well-tolerated and improves metabolic, hemodynamic, and survival outcomes in an ovine model of controlled hemorrhagic shock.

Biofabrication with microbial cellulose: from bioadaptive designs to living materials

Nanocellulose is not only a renewable material but also brings functions that are opening new technological opportunities. Here we discuss a special subset of this material, in its fibrillated form, which is produced by aerobic microorganisms, namely, bacterial nanocellulose (BNC). BNC offers distinct advantages over plant-derived counterparts, including high purity and high degree of polymerization as well as crystallinity, strength, and water-holding capacity, among others. More remarkably, beyond classical fermentative protocols, it is possible to grow BNC on non-planar interfaces, opening new possibilities in the assembly of advanced bottom-up structures. In this review, we discuss the recent advances in the area of BNC-based biofabrication of three-dimensional (3D) designs by following solid- and soft-material templating. These methods are shown as suitable platforms to achieve bioadaptive constructs comprising highly interlocked biofilms that can be tailored with precise control over nanoscale morphological features. BNC-based biofabrication opens applications that are not possible by using traditional manufacturing routes, including direct ink writing of hydrogels. This review emphasizes the critical contributions of microbiology, colloid and surface science, as well as additive manufacturing in achieving bioadaptive designs from living matter. The future impact of BNC biofabrication is expected to take advantage of material and energy integration, residue utilization, circularity and social latitudes. Leveraging existing infrastructure, the scaleup of biofabrication routes will contribute to a new generation of advanced materials rooted in exciting synergies that combine biology, chemistry, engineering and material sciences.

Injectable Ozone-Rich Nanocomposite Hydrogel Loaded with D-Mannose for Anti-Inflammatory and Cartilage Protection in Osteoarthritis Treatment

Osteoarthritis (OA) is a dynamic condition characterized by cartilage damage and synovial inflammation. Ozone (O3) shows potential therapeutic effects owing to its anti-inflammatory properties; however, its high reactivity and short half-life substantially limit its effectiveness in OA treatment. In this study, an ozone-rich thermosensitive nanocomposite hydrogel loaded with D-mannose is developed for OA treatment. Briefly, O3 is encapsulated in nanoparticles (NPs) composed of perfluorotributylamine and fluorinated hyaluronic acid to improve its stability. Next, D-mannose is conjugated with α-amino of the hydroxypropyl chitin (HPCH) via Schiff base to prepare MHPCH. These nanoparticles are encapsulated in MHPCH to produce O3 NPs@MHPCH. In vitro cell experiments demonstrate that the O3 NPs@MHPCH treatment significantly reduced VEGF and inflammation levels, accompanied by a decrease in inflammatory factors such as IL-1β, IL-6, TNF-α, and iNOS. Furthermore, O3 NPs@MHPCH promotes the expression of collagen II and aggrecan and stimulates chondrocyte proliferation. Additionally, in vivo studies show that O3 NPs@MHPCH significantly alleviated OA by reducing synovial inflammation, cartilage destruction, and subchondral bone remodeling. O3 NPs@MHPCH offers a promising option for improving the efficacy of O3 therapy and reducing the risk of synovial inflammation and cartilage degeneration in OA.

Oxygen self-sufficient nanodroplet composed of fluorinated polymer for high-efficiently PDT eradicating oral biofilm

Oral biofilm is the leading cause of dental caries, which is difficult to completely eradicate because of the complicated biofilm structure. What's more, the hypoxia environment of biofilm and low water-solubility of conventional photosensitizers severely restrict the therapeutic effect of photodynamic therapy (PDT) for biofilm. Although conventional photosensitizers could be loaded in nanocarriers, it has reduced PDT effect because of aggregation-caused quenching (ACQ) phenomenon. In this study, we fabricated an oxygen self-sufficient nanodroplet (PFC/TPA@FNDs), which was composed of fluorinated-polymer (FP), perfluorocarbons (PFC) and an aggregation-induced emission (AIE) photosensitizer (Triphenylamine, TPA), to eradicate oral bacterial biofilm and whiten tooth. Fluorinated-polymer was synthesized by polymerizing (Dimethylamino)ethyl methacrylate, fluorinated monomer and 1-nonanol monomer. The nanodroplets could be protonated and behave strong positive charge under bacterial biofilm acid environment promoting nanodroplets deeply penetrating biofilm. More importantly, the nanodroplets had extremely high PFC and oxygen loading efficacy because of the hydrophobic affinity between fluorinated-polymer and PFC to relieve the hypoxia environment and enhance PDT effect. Additionally, compared with conventional ACQ photosensitizers loaded system, PFC/TPA@FNDs could behave superior PDT effect to ablate oral bacterial biofilm under light irradiation due to the unique AIE effect. In vivo caries animal model proved the nanodroplets could reduce dental caries area without damaging tooth structure. Ex vivo tooth whitening assay also confirmed the nanodroplets had similar tooth whitening ability compared with commercial tooth whitener H2O2, while did not disrupt the surface microstructure of tooth. This oxygen self-sufficient nanodroplet provides an alternative visual angle for oral biofilm eradication in biomedicine.

Why Perfluorocarbon nanoparticles encounter bottlenecks in clinical translation despite promising oxygen carriers?

Artificial Oxygen Carriers (AOCs) have emerged as ground-breaking biomedical solutions, showcasing tremendous potential for enhancing human health and saving lives. Perfluorocarbon (PFC)-based AOCs, in particular, have garnered significant interest among researchers, leading to numerous clinical trials since the 1980 s. However, despite decades of exploration, the success rate has remained notably limited. This comprehensive review article delves into the landscape of clinical trials involving PFC compounds, shedding light on the challenges and factors contributing to the lack of clinical success with PFC nanoparticles till date. By scrutinizing the existing trials, the article aims to uncover the underlying issues like pharmacological side effects of the PFC and the nanomaterials used for the designing, complex formulation strategy and poor clinical trial designs of the formulation. More over each generation of the PFC formulation were discussed with details for their failure in the clinical trials limitations that block the path of PFC-based AOCs' full potential. Furthermore, the review emphasizes a forward-looking approach by outlining the future pathways and strategies essential for achieving success in clinical trials. AOCs require advanced yet biocompatible single-componentformulations. The new trend might be a novel drug delivery technique, like gel emulsion or reverse PFC emulsion with fluoro surfactants. Most importantly, well-planned clinical trials may end in a success story.

Controlled oxygen delivery to power tissue regeneration

Oxygen plays a crucial role in human embryogenesis, homeostasis, and tissue regeneration. Emerging engineered regenerative solutions call for novel oxygen delivery systems. To become a reality, these systems must consider physiological processes, oxygen release mechanisms and the target application. In this review, we explore the biological relevance of oxygen at both a cellular and tissue level, and the importance of its controlled delivery via engineered biomaterials and devices. Recent advances and upcoming trends in the field are also discussed with a focus on tissue-engineered constructs that could meet metabolic demands to facilitate regeneration.

Development of Perfluoro Decalin/Fluorinated Polyimide Core-Shell Microparticles via SPG Membrane Emulsification Using Methyl Perfluoropropyl Ether Cosolvent

Red blood cell-inspired perfluorocarbon-encapsulated core-shell particles have been developed for biomedical applications. Although the use of perfluorodecalin (FDC) is expected for core-shell particles owing to its high oxygen solubility, the low solubility of FDC in any organic solvent, owing to its fluorous properties, prevents its use in core-shell particles. In this study, a new cosolvent system composed of dichloromethane (DCM) and heptafluoropropyl methyl ether (HFPME) was found to dissolve both FDC and fluorinated polyimide (FPI) based on a systematic study using a phase diagram, achieving a homogeneous disperse phase for emulsification composed of oxygen-permeable FPI and oxygen-soluble FDC. Using this novel cosolvent system and Shirasu porous glass (SPG) membrane emulsification, FDC-encapsulated FPI shell microparticles were successfully prepared for the first time. In addition to oxygenation, demonstrated using hypoxia-responsive HeLa cells, the fabricated core-shell microparticles exhibited monodispersity, excellent stability, biocompatibility, and oxygen capacity.

Carbon monoxide release from ultrasound-sensitive microbubbles improves endothelial cell growth

Carbon monoxide is a gasotransmitter that may be beneficial for vascular tissue engineering and regenerative medicine strategies because it can promote endothelial cell (EC) proliferation and migration by binding to heme-containing compounds within cells. For example, CO may be beneficial for vascular cognitive impairment and dementia because many patients' disrupted blood-brain barriers do not heal naturally. However, control of the CO dose is critical, and new controlled delivery methods need to be developed. This study developed ultrasound-sensitive microbubbles with a carefully controlled precipitation technique, loaded them with CO, and assessed their ability to promote EC proliferation and function. Microbubbles fabricated with perfluoropentane exhibited good stability at room temperature, but they could still be ruptured and release CO in culture with application of ultrasound. Microbubbles synthesized from the higher boiling point compound, perfluorohexane, were too stable at physiological temperature. The lower-boiling point perfluoropentane microbubbles had good biocompatibility and appeared to improve VE-cadherin expression when CO was loaded in the bubbles. Finally, tissue phantoms were used to show that an imaging ultrasound probe can efficiently rupture the microbubbles and that the CO-loaded microbubbles can improve EC spreading and proliferation compared to control conditions without microbubbles as well as microbubbles without application of ultrasound. Overall, this study demonstrated the potential for use of these ultrasound-sensitive microbubbles for improving blood vessel endothelialization.

Cross-linked Triblock Peptide Capsules as Potential Oxygen Carriers

Perfluorodecalin (PFD)-filled capsules have been studied for over 15 years as artificial oxygen carriers. However, none of these capsules combines good biocompatibility, good mechanical stability and dispersion stability. Here we propose to use synthetic triblock peptides containing a central block of cysteine units as a cross-linking shell material for capsules with both good biocompatibility and stability. Together with outer aspartate units and inner phenylalanine units, the resulting amphiphilic triblock peptides can encapsulate PFD efficiently to prepare capsules with a suitable diameter, a certain mechanical strength, a large diffusion constant, fast gas exchange rates, and little cytotoxicity. Given the above advantages, these PFD-filled peptide capsules are very promising as potential artificial oxygen carriers.

Multiphase Under-Liquid Biofabrication With Living Soft Matter: A Route to Customize Functional Architectures With Microbial Nanocellulose

The growth of aerobic microbes at air-water interfaces typically leads to biofilm formation. Herein, a fermentative alternative that relies on oil-water interfaces to support bacterial activity and aerotaxis is introduced. The process uses under-liquid biofabrication by structuring bacterial nanocellulose (BNC) to achieve tailorable architectures. Cellulose productivity in static conditions is first evaluated using sets of oil homologues, classified in order of polarity. The oils are shown for their ability to sustain bacterial growth and BNC production according to air transfer and solubilization, both of which impact the physiochemical properties of the produced biofilms. The latter are investigated in terms of their morphological (fibril size and network density), structural (crystallinity) and physical-mechanical (surface area and strength) features. The introduced under-liquid biofabrication is demonstrated for the generation of BNC-based macroscale architectures and compartmentalized soft matter. This can be accomplished following three different routes, namely, 3D under-liquid networking (multi-layer hydrogels/composites), emulsion templating (capsules, emulgels, porous materials), and anisotropic layering (Janus membranes). Overall, the proposed platform combines living matter and multi-phase systems as a robust option for material development with relevance in biomedicine, soft robotics, and bioremediation, among others.

Injectable Alginate Complex Hydrogel Loaded with Dual-Drug Nanovectors Offers Effective Photochemotherapy against Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), accounting for approximately 20% of breast cancer cases, is a particular subtype that lacks tumor-specific targets and is difficult to treat due to its high aggressiveness and poor prognosis. Chemotherapy remains the major systemic treatment for TNBC. However, its applicability and efficacy in the clinic are usually concerning due to a lack of targeting, adverse side effects, and occurrence of multidrug resistance, suggesting that the development of effective therapeutics is still highly demanded nowadays. In this study, an injectable alginate complex hydrogel loaded with indocyanine green (ICG)-entrapped perfluorocarbon nanoemulsions (IPNEs) and camptothecin (CPT)-doped chitosan nanoparticles (CCNPs), named IPECCNAHG, was developed for photochemotherapy against TNBC. IPNEs with perfluorocarbon can induce hyperthermia and generate more singlet oxygen than an equal dose of free ICG upon near-infrared (NIR) irradiation to achieve photothermal and photodynamic therapy. CCNPs with positive charge may facilitate cellular internalization and provide sustained release of CPT to carry out chemotherapy. Both nanovectors can stabilize agents in the same hydrogel system without interactions. IPECCNAHG integrating IPNEs and CCNPs enables stage-wise combinational therapeutics that may overcome the issues described above. With 60 s of NIR irradiation, IPECCNAHG significantly inhibited the growth of MDA-MB-231 tumors in the mice without systemic toxicity within the 21 day treatment. We speculate that such anticancer efficacy was accomplished by phototherapy followed by chemotherapy, where cancer cells were first destroyed by IPNE-derived hyperthermia and singlet oxygen, followed by sustained damage with CPT after internalization of CCNPs; a two-stage tumoricidal process. Taken together, the developed IPECCNAHG is anticipated to be a feasible tool for TNBC treatment in the clinic.

Nanocatalysts for modulating antitumor immunity: fabrication, mechanisms and applications

Immunotherapy harnesses the inherent immune system in the body to generate systemic antitumor immunity, offering a promising modality for defending against cancer. However, tumor immunosuppression and evasion seriously restrict the immune response rates in clinical settings. Catalytic nanomedicines can transform tumoral substances/metabolites into therapeutic products in situ, offering unique advantages in antitumor immunotherapy. Through catalytic reactions, both tumor eradication and immune regulation can be simultaneously achieved, favoring the development of systemic antitumor immunity. In recent years, with advancements in catalytic chemistry and nanotechnology, catalytic nanomedicines based on nanozymes, photocatalysts, sonocatalysts, Fenton catalysts, electrocatalysts, piezocatalysts, thermocatalysts and radiocatalysts have been rapidly developed with vast applications in cancer immunotherapy. This review provides an introduction to the fabrication of catalytic nanomedicines with an emphasis on their structures and engineering strategies. Furthermore, the catalytic substrates and state-of-the-art applications of nanocatalysts in cancer immunotherapy have also been outlined and discussed. The relationships between nanostructures and immune regulating performance of catalytic nanomedicines are highlighted to provide a deep understanding of their working mechanisms in the tumor microenvironment. Finally, the challenges and development trends are revealed, aiming to provide new insights for the future development of nanocatalysts in catalytic immunotherapy.

Ultrasound-responsive microbubbles and nanodroplets: A pathway to targeted drug delivery

Ultrasound-responsive agents have shown great potential as targeted drug delivery agents, effectively augmenting cell permeability and facilitating drug absorption. This review focuses on two specific agents, microbubbles and nanodroplets, and provides a sequential overview of their drug delivery process. Particular emphasis is given to the mechanical response of the agents under ultrasound, and the subsequent physical and biological effects on the cells. Finally, the state-of-the-art in their pre-clinical and clinical implementation are discussed. Throughout the review, major challenges that need to be overcome in order to accelerate their clinical translation are highlighted.

The application of nanotechnology in kidney transplantation

Kidney transplantation is a crucial treatment option for end-stage renal disease patients, but challenges related to graft function, rejection and immunosuppressant side effects persist. This review highlights the potential of nanotechnology in addressing these challenges. Nanotechnology offers innovative solutions to enhance organ preservation, evaluate graft function, mitigate ischemia-reperfusion injury and improve drug delivery for immunosuppressants. The integration of nanotechnology holds promise for improving outcomes in kidney transplantation.

The effect of oxygen supply using perfluorocarbon-based nanoemulsions on human hair growth

Hair dermal papilla cells (hDPCs) play a crucial role in hair growth and regeneration, and their function is influenced by nutrient and oxygen supply. A microenvironment with significantly low oxygen (O2) levels, known as anoxic conditions (<0.2%) due to oxygen deficiency, hinders hDPC promotion and retards hair regrowth. Here, a nanoemulsion (NE) based on perfluorooctyl bromide (PFOB), a member of the perfluorocarbon family, is presented to provide a sustainable O2 supply and maintain physical stability in vitro. The PFOB-NE has been shown to continuously release oxygen for 36 h, increasing and maintaining the O2 concentration in the anoxic microenvironment of up to 0.8%. This sustainable O2 supply using PFOB-NE has promoted hDPC growth and also induced a complex cascade of effects. These effects encompass regulation via inhibiting lactate accumulation caused via oxygen deficiency, increasing lactate dehydrogenase activity, and promoting the expression of genes, such as the hypoxia-inducible factor 1 family and NADPH oxidase 4 under anoxic conditions. Sustained O2 supply is shown to enhance human hair organ elongation approximately four times compared to the control under anoxic conditions. In conclusion, the perfluorocarbon-based NE containing oxygen proves to be an important strategic tool for improving hair growth and alleviating hair loss.

Oxygen generating biomaterials at the forefront of regenerative medicine: advances in bone regeneration

Globally, an annual count of more than two million bone transplants is conducted, with conventional treatments, including metallic implants and bone grafts, exhibiting certain limitations. In recent years, there have been significant advancements in the field of bone regeneration. Oxygen tension regulates cellular behavior, which in turn affects tissue regeneration through metabolic programming. Biomaterials with oxygen release capabilities enhance therapeutic effectiveness and reduce tissue damage from hypoxia. However, precise control over oxygen release is a significant technical challenge, despite its potential to support cellular viability and differentiation. The matrices often used to repair large-size bone defects do not supply enough oxygen to the stem cells being used in the regeneration process. Hypoxia-induced necrosis primarily occurs in the central regions of large matrices due to inadequate provision of oxygen and nutrients by the surrounding vasculature of the host tissues. Oxygen generating biomaterials (OGBs) are becoming increasingly significant in enhancing our capacity to facilitate the bone regeneration, thereby addressing the challenges posed by hypoxia or inadequate vascularization. Herein, we discussed the key role of oxygen in bone regeneration, various oxygen source materials and their mechanism of oxygen release, the fabrication techniques employed for oxygen-releasing matrices, and novel emerging approaches for oxygen delivery that hold promise for their potential application in the field of bone regeneration.

Strategies to Reverse Hypoxic Tumor Microenvironment for Enhanced Sonodynamic Therapy

Sonodynamic therapy (SDT) has emerged as a highly effective modality for the treatment of malignant tumors owing to its powerful penetration ability, noninvasiveness, site-confined irradiation, and excellent therapeutic efficacy. However, the traditional SDT, which relies on oxygen availability, often fails to generate a satisfactory level of reactive oxygen species because of the widespread issue of hypoxia in the tumor microenvironment of solid tumors. To address this challenge, various approaches are developed to alleviate hypoxia and improve the efficiency of SDT. These strategies aim to either increase oxygen supply or prevent hypoxia exacerbation, thereby enhancing the effectiveness of SDT. In view of this, the current review provides an overview of these strategies and their underlying principles, focusing on the circulation of oxygen from consumption to external supply. The detailed research examples conducted using these strategies in combination with SDT are also discussed. Additionally, this review highlights the future prospects and challenges of the hypoxia-alleviated SDT, along with the key considerations for future clinical applications. These considerations include the development of efficient oxygen delivery systems, the accurate methods for hypoxia detection, and the exploration of combination therapies to optimize SDT outcomes.

Nanoplatform-enhanced photodynamic therapy for the induction of immunogenic cell death

As an efficient, non-invasive, low-side-effect, and highly selective cancer therapy, photodynamic therapy (PDT) is used to treat various malignant tumors. However, the inefficiency of dealing with deep tumors and metastatic lesions highly limits the use of PDT. Immunogenic cell death (ICD) is a particular form of tumor cell death that could elicit a tumor-special immune response, leading to a systemic anti-tumor effect and providing therapeutic benefits for metastatic lesions. In this regard, it is crucial to enhance the ability of PDT to induce ICD. Luckily, advanced nanotechnology created many promising ways to improve the immunogenicity of PDT and achieve photoimmunotherapy. This review summarizes the emerging strategies for triggering immunogenic cell death via nanoplatform-enhanced PDT, with particular emphasis on their advantages in photoimmunotherapy. We highlight the nanoplatforms classified according to the basic principles of photodynamic therapy and immunogenic cell death, which provides a valuable reference for the design of nanoplatform for photoimmunotherapy. In addition, we also discuss the current situation and prospect of nano-based photoimmunotherapy in clinical studies.

Simple droplet microfluidics platform for drug screening on cancer spheroids

3D in vitro biological systems are progressively replacing 2D systems to increase the physiological relevance of cellular studies. Microfluidics-based approaches can be powerful tools towards such biomimetic systems, but often require high-end complicated and expensive processes and equipment for microfabrication. Herein, a drug screening platform is proposed, minimizing technicality and manufacturing steps. It provides an alternate way of spheroid generation in droplets in tubes. Droplet microfluidics then elicit multiple droplets merging events at programmable times, to submit sequentially the spheroids to chemotherapy and to reagents for cytotoxicity screening. After a comprehensive study of tumorogenesis within the droplets, the system is validated for drug screening (IC50) with chemotherapies in cancer cell lines as well as cells from a patient-derived-xenografts (PDX). As compared to microtiter plates methods, our system reduces the initial number of cells up to 10 times and opens new avenues towards primary tumors drug screening approaches.

Fabrication of oxygen-carrying microparticles functionalized with liver ECM-proteins to improve phenotypic three-dimensional in vitro liver assembly, function, and responses

Oxygen and extracellular matrix (ECM)-derived biopolymers play vital roles in regulating many cellular functions in both the healthy and diseased liver. This study highlights the significance of synergistically tuning the internal microenvironment of three-dimensional (3D) cell aggregates composed of hepatocyte-like cells from the HepG2 human hepatocellular carcinoma cell line and hepatic stellate cells (HSCs) from the LX-2 cell line to enhance oxygen availability and phenotypic ECM ligand presentation for promoting the native metabolic functions of the human liver. First, fluorinated (PFC) chitosan microparticles (MPs) were generated with a microfluidic chip, then their oxygen transport properties were studied using a custom ruthenium-based oxygen sensing approach. Next, to allow for integrin engagements the surfaces of these MPs were functionalized using liver ECM proteins including fibronectin, laminin-111, laminin-511, and laminin-521, then they were used to assemble composite spheriods along with HepG2 cells and HSCs. After in vitro culture, liver-specific functions and cell adhesion patterns were compared between groups and cells showed enhanced liver phenotypic responses to laminin-511 and 521 as evidenced via enhanced E-cadherin and vinculin expression, as well as albumin and urea secretion. Furthermore, hepatocytes and HSCs exhibited more pronounced phenotypic arrangements when cocultured with laminin-511 and 521 modified MPs providing clear evidence that specific ECM proteins have distinctive roles in the phenotypic regulation of liver cells in engineering 3D spheroids. This study advances efforts to create more physiologically relevant organ models allowing for well-defined conditions and phenotypic cell signaling which together improve the relevance of 3D spheroid and organoid models.

Research Progress in Oxygen Carrier Design and Application

Ischemia or hypoxia can lead to pathological changes in the metabolism and function of tissues and then lead to various diseases. Timely and effective blood resuscitation or improvement of hypoxia is very important for the treatment of diseases. However, there is a need to develop stable, nontoxic, and immunologically inert oxygen carriers due to limitations such as blood shortages, different blood types, and the risk of transmitting infections. With the development of various technologies, oxygen carriers based on hemoglobin and perfluorocarbon have been widely studied in recent years. This paper reviews the development and application of hemoglobin and perfluorocarbon oxygen carriers. The design of oxygen carriers was analyzed, and their application as blood substitutes or oxygen carriers in various hypoxic diseases was discussed. Finally, the characteristics and future research of ideal oxygen carriers were prospected to provide reference for follow-up research.

Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

Photodynamic therapy (PDT), with its advantages of high targeting, minimally invasive, and low toxicity side effects, has been widely used in the clinical therapy of various tumors, especially superficial tumors. However, the tumor microenvironment (TME) presents hypoxia due to the low oxygen (O2 ) supply caused by abnormal vascularization in neoplastic tissues and high O2 consumption induced by the rapid proliferation of tumor cells. The efficacy of oxygen-consumping PDT can be hampered by a hypoxic TME. To address this problem, researchers have been developing advanced nanoplatforms and strategies to enhance the therapeutic effect of PDT in tumor treatment. This review summarizes recent advanced PDT therapeutic strategies to against the hypoxic TME, thus enhancing PDT efficacy, including increasing O2 content in TME through delivering O2 to the tumors and in situ generations of O2 ; decreasing the O2 consumption during PDT by design of type I photosensitizers. Moreover, recent synergistically combined therapy of PDT and other therapeutic methods such as chemotherapy, photothermal therapy, immunotherapy, and gas therapy is accounted for by addressing the challenging problems of mono PDT in hypoxic environments, including tumor resistance, proliferation, and metastasis. Finally, perspectives of the opportunities and challenges of PDT in future clinical research and translations are provided.

Microneedle-assisted transdermal delivery of perfluorotripropylamine-based oxygenated emulsion gel loaded with 5-aminolevulinic acid for enhanced photodynamic therapy of cutaneous squamous cell carcinoma

Topical photodynamic therapy (TPDT) is a clinical treatment for cutaneous squamous cell carcinoma (CSCC). However, the therapeutic efficacy of TPDT for CSCC is significantly weakened by hypoxia, which is caused by the oxygen-poor environment of the skin and CSCC and by the high oxygen consumption of TPDT itself. To overcome these problems, we developed a topically applied perfluorotripropylamine-based oxygenated emulsion gel loaded with the photosensitizer 5-ALA (5-ALA-PBOEG) by a simple ultrasound-assisted emulsion method. With the aid of the microneedle roller, 5-ALA-PBOEG dramatically increased the accumulation of 5-ALA in the epidermis and the dermis, as well as throughout the dermis; a total of 67.6% ± 9.97% of the applied dose penetrated into and through the dermis, which is 19.1±3.2-fold that of the 5-ALA-PBOEG without microneedle treatment group, and 16.9±0.3-fold that of the aminolevulinic acid hydrochloride topical powder treatment group (p<0.001). Meanwhile, PBOEG enhanced the singlet oxygen yield of 5-ALA-induced protoporphyrin IX. The results of in vivo antitumor activity in human epidermoid carcinoma (A431) bearing mice showed that by increasing the oxygen content in tumor tissues, the developed 5-ALA-PBOEG plus microneedle treatment and laser irradiation showed better tumor growth inhibition than the respective control formulations. In addition, the results of safety studies, including the multiple-dose skin irritation study, allergy tests, and skin H&E staining, demonstrated the safety of 5-ALA-PBOEG plus microneedle treatment. In conclusion, the 5-ALA-PBOEG plus microneedle treatment shows great potential in the fight against CSCC and other skin cancers.

Perfluorotributylamine-Loaded Albumin Nanoparticles Downregulate Platelet-Derived TGFβ to Inhibit Tumor Metastasis

Tumor metastasis contributes to the low overall survival of tumor patients, while transforming growth factor-β (TGFβ) has been recognized as a prominently promoting factor in the development of tumor metastasis. Platelets reserve abundant TGFβ, which will be secreted to peripheral blood after activation, and they are the dominant source of circulating TGFβ. Therefore, downregulation of platelet-derived TGFβ is expected to inhibit the metastasis of circulating tumor cells. Here, unfolded human serum albumin (HSA)-coated perfluorotributylamine (PFTBA) nanoparticles were constructed to display a favorable platelet delivery and an antiplatelet effect to downregulate platelet-derived TGFβ in vitro and in blood plasma. PFTBA@HSA-mediated TGFβ downregulation impaired epithelial-mesenchymal transition of tumor cells as well as their migration and invasion behaviors and enhanced immune surveillance of NK cells. Intravenous injection of PFTBA@HSA effectively reduced tumor metastasis on the lungs or liver to improve the survival rate of mice on multiple metastatic models, including CT26 colon cancer, B16F10 melanoma, and 4T1 breast cancer. Compared with the clinical antiplatelet drug ticagrelor, PFTBA@HSA reduced bleeding risk when displaying a favorable downregulation on platelet-derived TGFβ, thereby obtaining a higher therapy benefit. Together, this study confirmed that downregulation of platelet-derived TGFβ by PFTBA@HSA will be a potential approach and therapeutic candidate for the prevention of tumor metastasis.

Perfluorocarbons: A perspective of theranostic applications and challenges

Perfluorocarbon (PFC) are biocompatible compounds, chemically and biologically inert, and lacks toxicity as oxygen carriers. PFCs nanoemulsions and nanoparticles (NPs) are highly used in diagnostic imaging and enable novel imaging technology in clinical imaging modalities to notice and image pathological and physiological alterations. Therapeutics with PFCs such as the innovative approach to preventing thrombus formation, PFC nanodroplets utilized in ultrasonic medication delivery in arthritis, or PFC-based NPs such as Perfluortributylamine (PFTBA), Pentafluorophenyl (PFP), Perfluorohexan (PFH), Perfluorooctyl bromide (PFOB), and others, recently become renowned for oxygenating tumors and enhancing the effects of anticancer treatments as oxygen carriers for tumor hypoxia. In this review, we will discuss the recent advancements that have been made in PFC's applications in theranostic (therapeutics and diagnostics) as well as assess the benefits and drawbacks of these applications.

Recent Advances in Nanoplatform Construction Strategy for Alleviating Tumor Hypoxia

Hypoxia is a typical feature of most solid tumors and has important effects on tumor cells' proliferation, invasion, and metastasis. This is the key factor that leads to poor efficacy of different kinds of therapy including chemotherapy, radiotherapy, photodynamic therapy, etc. In recent years, the construction of hypoxia-relieving functional nanoplatforms through nanotechnology has become a new strategy to reverse the current situation of tumor microenvironment hypoxia and improve the effectiveness of tumor treatment. Here, the main strategies and recent progress in constructing nanoplatforms are focused on to directly carry oxygen, generate oxygen in situ, inhibit mitochondrial respiration, and enhance blood perfusion to alleviate tumor hypoxia. The advantages and disadvantages of these nanoplatforms are compared. Meanwhile, nanoplatforms based on organic and inorganic substances are also summarized and classified. Through the comprehensive overview, it is hoped that the summary of these nanoplatforms for alleviating hypoxia could provide new enlightenment and prospects for the construction of nanomaterials in this field.

The impact of intravenous dodecafluoropentane on a murine model of acute lung injury

INTRODUCTION

Intravenous oxygen therapeutics present an appealing option for improving arterial oxygenation in patients with acute hypoxemic respiratory failure, while limiting iatrogenic injury from conventional respiratory management.

METHODS

We used an established two-hit murine model of acute lung injury (ARDS/VILI) to evaluate the effect of intravenous dodecafluoropentane (DDFPe) on oxygen saturation and bronchoalveolar lavage cell counts and protein levels. Twenty hours after challenge with intratracheal lipopolysaccharide, mice were intubated and ventilated with high tidal volumes (4 h) to produce acute lung injury. DDFPe (0.6 mL/kg) or saline was administered by IV bolus injection at the initiation of mechanical ventilation and again at 2 h. Oxygen saturation was measured every 15 min. Bronchoalveolar lavage was performed at the conclusion of the experiment.

RESULTS

The two-hit ARDS/VILI model produced substantial inflammatory acute lung injury reflected by markedly increased bronchoalveolar lavage (BAL) cell counts compared to BAL cell counts in spontaneous breathing controls (5.29 ± 1.50 × 10^-6 vs 0.74 ± 0.014 × 10^-6 cells/mL) Similarly, BAL protein levels were markedly elevated in ARDS/VILI-challenged mice compared with spontaneous breathing controls (1109.27 ± 223.80 vs 129.6 ± 9.75 ng/mL). We fit a linear mixed effects model that showed a significant difference in oxygen saturation over time between DDFPe-treated mice and saline-treated mice, with separation starting after the 2-h injection. DDFPe-treated ARDS/VILI-challenged mice also exhibited significant reductions in BAL cell counts but not in BAL protein.

CONCLUSION

DDFPe improves oxygen saturation in a murine model of ARDS/VILI injury with the potential for serving as an intravenous oxygen therapeutic.

Oxygen-releasing biomaterials for chronic wounds breathing: From theoretical mechanism to application prospect

Chronic wounds have always been considered as "gordian knots" in medicine, in which hypoxia plays a key role in blocking healing. To address this challenge, although tissue reoxygenation therapy based on hyperbaric oxygen therapy (HBOT) has been performed clinically for several years, the bench to bedside still urges the evolution of oxygen-loading and -releasing strategies with explicit benefits and consistent outcome. The combination of various oxygen carriers with biomaterials has gained momentum as an emerging therapeutic strategy in this field, exhibiting considerable application potential. This review gives an overview of the essential relationship between hypoxia and delayed wound healing. Further, detailed characteristics, preparation methods and applications of various oxygen-releasing biomaterials (ORBMs) will be elaborated, including hemoglobin, perfluorocarbon, peroxide, and oxygen-generating microorganisms, those biomaterials are applied to load, release or generate a vast of oxygen to relieve the hypoxemia and bring the subsequent cascade effect. The pioneering papers regarding to the ORBMs practice are presented and trends toward hybrid and more precise manipulation are summarized.

Insight on Oxygen-Supplying Biomaterials Used to Enhance Cell Survival, Retention, and Engraftment for Tissue Repair

Oxygen is one of the essential requirements for cell survival, retention, and proliferation. The field of regenerative medicine and tissue engineering (TE) has realized considerable achievements for the regeneration of tissues. However, tissue regeneration still lacks the full functionality of solid organ implantations; limited cell survival and retention due to oxidative stress and hypoxia in the deeper parts of tissues remains a perpetual challenge. Especially prior to neovascularization, hypoxia is a major limiting factor, since oxygen delivery becomes crucial for cell survival throughout the tissue-engineered construct. Oxygen diffusion is generally limited in the range 100-200 μm of the thickness of a scaffold, and the cells located beyond this distance face oxygen deprivation, which ultimately leads to hypoxia. Furthermore, before achieving functional anastomosis, implanted tissues will be depleted of oxygen, resulting in hypoxia (<5% dissolved oxygen) followed by anoxic (<0.5% dissolved oxygen) microenvironments. Different types of approaches have been adopted to establish a sustained oxygen supply both in vitro and in vivo. In this review, we have summarized the recent developments in oxygen-generating and/or releasing biomaterials for enhancing cell survival in vitro, as well as for promoting soft and hard tissue repair, including skin, heart, nerve, pancreas, muscle, and bone tissues in vivo. In addition, redox-scavenging biomaterials and oxygenated scaffolds have also been highlighted. The surveyed results have shown significant promise in oxygen-producing biomaterials and oxygen carriers for enhancing cell functionality for regenerative medicine and TE applications. Taken together, this review provides a detailed overview of newer approaches and technologies for oxygen production, as well as their applications for bio-related disciplines.

A Perfluorocarbon-Coated ZrP Cation Exchanger with Excellent Ammonium Selectivity and Chemical Stability: An Oral Sorbent for End-Stage Kidney Disease (ESKD)

An oral sorbent to remove NH₄⁺ within the small intestine of end-stage kidney disease (ESKD) patients could reduce blood urea levels and diminish their dialysis treatment burden. But current sorbent materials like amorphous zirconium phosphate particles Zr(HPO₄)₂·H₂O (ZrP) lack the selectivity to remove NH₄⁺ in water solution with other competing ions. Our previous work found that a gas-permeable, hydrophobic polydimethylsiloxane (PDMS) coating on ZrP improved the material's selectivity for NH₄⁺. However, a competing ion Ca²⁺ was still removed by PDMS-coated ZrP sorbent, and the permeability of the PDMS coating to Ca²⁺ was increased after low-pH stomach-like condition exposure. An alternative hydrophobic and gas permeable coating has been investigated─perfluorooctyltriethoxysilane (FOTS). The coating was attached in place of PDMS to a tetraethyl orthosilicate-coated ZrP surface. Surface atomic composition analysis and scanning electron microscopy observation verified the successful application of the FOTS coating. Water contact angle analysis validated the FOTS coating was hydrophobic (145.0 ± 3.2°). In vitro competing ion studies indicated the FOTS coating attached to ZrP increased NH₄⁺ removal by 53% versus uncoated ZrP. FOTS offers complete selectivity for NH₄⁺ over Ca²⁺ with similar NH₄⁺ capacity as the previous PDMS coating. Moreover, FOTS-coated ZrP maintained NH₄⁺ removal capacity and selectivity after the acid exposure study, indicating excellent acid resistance while NH₄⁺ selectivity of ZrP-PDMS decreased by 72%. The results suggested that FOTS-coated ZrP is promising as an oral sorbent for ESKD patients.

Biocompatibility of the oxygen carrier polymerized human hemoglobin towards HepG2/C3A cells

Hemoglobin (Hb) based oxygen carriers (HBOCs) are designed to minimize the toxicity of extracellular Hb, while preserving its high oxygen-carrying capacity for oxygen delivery to cells. Polymerized human Hb (PolyHb) is a novel type of nanosized HBOC synthesized via glutaraldehyde-mediated crosslinking of free Hb, and which preserves the predominant quaternary state during the crosslinking reaction (low oxygen affinity tense (T) quaternary state PolyHb is synthesized at 0% Hb oxygen saturation, and high oxygen affinity relaxed (R) quaternary state PolyHb is synthesized at 100% Hb oxygen saturation). Major potential applications for PolyHbs, and HBOCs in general, include oxygenation of bioreactor systems containing large liver cell masses, and ex-vivo perfusion preservation of explanted liver grafts. The toxicity of these compounds toward liver cells must be evaluated before testing their use in these complex systems for oxygen delivery. Herein, we characterized the effect of PolyHbs on the hepatoma cell line HepG2/C3A, used as a model hepatocyte and as a cell line used in some investigational bioartificial liver support devices. HepG2/C3A cells were incubated in cell culture media containing PolyHbs or unmodified Hb at concentrations up to 50 mg/mL and for up to 6 days. PolyHbs were well tolerated at a dose of 10 mg/mL, with no significant decrease in cell viability; however, proliferation was inhibited as much as 10-fold after 6 days of exposure at 50 mg/mL. Secretion of albumin, and urea, as well as glucose and ammonia removal were measured in presence of 10 mg/mL of PolyHbs or unmodified Hb. In addition, methoxy- and ethoxy-resorufin deacetylase (MROD and EROD) activities, which reflect cytochrome P450 metabolism, were measured. R-state PolyHb displayed improved or intact activity in 3 out of 7 functions compared to unmodified Hb. T-state PolyHb displayed improved or intact activity in 4 out of 7 functions compared to unmodified Hb. Thus, PolyHbs, both in the R-state and T-state, are safer to use at a concentration of 10 mg/mL as compared to unmodified Hb in static culture liver-related applications.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Measurement of Diffusion of Atmospheric Gases in a Liquid Perfluoro Compound by Means of an Optical Technique

We report on accurate measurements of Fickian diffusion coefficients in binary mixtures consisting of hydrofluoroether (a perfluoro compound of methoxy-nonafluorobutane or HFE-7100) with dissolved atmospheric gases CO₂, N₂, and O₂ in the limit of an infinite dilution of the gas. We show that the use of optical digital interferometry (ODI) allows the determination of diffusion coefficients of dissolved gases with relatively small standard uncertainties for this class of experiments. In addition, we illustrate the ability of an optical approach to determine the gas concentration. We compare the capacity of four mathematical models, singly used in the literature, to obtain diffusion coefficients by applying them to the processing of a large amount of experimental data. We quantify their systematic errors and standard uncertainties. The temperature behavior of the diffusion coefficients measured in the range of 10 to 40 °C is consistent with the behavior of the same gases in other solvents available in the literature.

Oxygen therapy alternatives in COVID-19: From classical to nanomedicine

Around 10-15% of COVID-19 patients affected by the Delta and the Omicron variants exhibit acute respiratory insufficiency and require intensive care unit admission to receive advanced respiratory support. However, the current ventilation methods display several limitations, including lung injury, dysphagia, respiratory muscle atrophy, and hemorrhage. Furthermore, most of the ventilatory techniques currently offered require highly trained professionals and oxygen cylinders, which may attain short supply owing to the high demand and misuse. Therefore, the search for new alternatives for oxygen therapeutics has become extremely important for maintaining gas exchange in patients affected by COVID-19. This review highlights and suggest new alternatives based on micro and nanostructures capable of supplying oxygen and/or enabling hematosis during moderate or acute COVID-19 cases.

Oxygen-Generating Biomaterials for Translational Bone Regenerative Engineering

Successful regeneration of critical-size defects remains one of the significant challenges in regenerative engineering. These large-scale bone defects are difficult to regenerate and are often reconstructed with matrices that do not provide adequate oxygen levels to stem cells involved in the regeneration process. Hypoxia-induced necrosis predominantly occurs in the center of large matrices since the host tissue's local vasculature fails to provide sufficient nutrients and oxygen. Indeed, utilizing oxygen-generating materials can overcome the central hypoxic region, induce tissue in-growth, and increase the quality of life for patients with extensive tissue damage. This article reviews recent advances in oxygen-generating biomaterials for translational bone regenerative engineering. We discussed different oxygen-releasing and delivery methods, fabrication methods for oxygen-releasing matrices, biology, oxygen's role in bone regeneration, and emerging new oxygen delivery methods that could potentially be used for bone regenerative engineering.

Multiple Linear Regression Predictive Modeling of Colloidal and Fluorescence Stability of Theranostic Perfluorocarbon Nanoemulsions

Perfluorocarbon nanoemulsions (PFC-NEs) are widely used as theranostic nanoformulations with fluorescent dyes commonly incorporated for tracking PFC-NEs in tissues and in cells. Here, we demonstrate that PFC-NE fluorescence can be fully stabilized by controlling their composition and colloidal properties. A quality-by-design (QbD) approach was implemented to evaluate the impact of nanoemulsion composition on colloidal and fluorescence stability. A full factorial, 12-run design of experiments was used to study the impact of hydrocarbon concentration and perfluorocarbon type on nanoemulsion colloidal and fluorescence stability. PFC-NEs were produced with four unique PFCs: perfluorooctyl bromide (PFOB), perfluorodecalin (PFD), perfluoro(polyethylene glycol dimethyl ether) oxide (PFPE), and perfluoro-15-crown-5-ether (PCE). Multiple linear regression modeling (MLR) was used to predict nanoemulsion percent diameter change, polydispersity index (PDI), and percent fluorescence signal loss as a function of PFC type and hydrocarbon content. The optimized PFC-NE was loaded with curcumin, a known natural product with wide therapeutic potential. Through MLR-supported optimization, we identified a fluorescent PFC-NE with stable fluorescence that is unaffected by curcumin, which is known to interfere with fluorescent dyes. The presented work demonstrates the utility of MLR in the development and optimization of fluorescent and theranostic PFC nanoemulsions.

Nanotechnological strategies to increase the oxygen content of the tumor

Hypoxia is a negative prognostic indicator of solid tumors, which not only changes the survival state of tumors and increases their invasiveness but also remarkably reduces the sensitivity of tumors to treatments such as radiotherapy, chemotherapy and photodynamic therapy. Thus, developing therapeutic strategies to alleviate tumor hypoxia has recently been considered an extremely valuable target in oncology. In this review, nanotechnological strategies to elevate oxygen levels in tumor therapy in recent years are summarized, including (I) improving the hypoxic tumor microenvironment, (II) oxygen delivery to hypoxic tumors, and (III) oxygen generation in hypoxic tumors. Finally, the challenges and prospects of these nanotechnological strategies for alleviating tumor hypoxia are presented.

Microbubbles for human diagnosis and therapy

Microbubbles (MBs) were observed for the first time in vivo as a curious consequence of quick saline injection during ultrasound (US) imaging of the aortic root, more than 50 years ago. From this serendipitous event, MBs are now widely used as contrast enhancers for US imaging. Their intrinsic properties described in this review, allow a multitude of designs, from shell to gas composition but also from grafting targeting agents to drug payload encapsulation. Indeed, the versatile MBs are deeply studied for their dual potential in imaging and therapy. As presented in this paper, new generations of MBs now opens perspectives for targeted molecular imaging along with the development of new US imaging systems. This review also presents an overview of the different therapeutic strategies with US and MBs for cancer, cardiovascular diseases, and inflammation. The overall aim is to overlap those fields in order to find similarities in the MBs application for treatment enhancement associated with US. To conclude, this review explores the new scales of MBs technologies with nanobubbles development, and along concurrent advances in the US imaging field. This review ends by discussing perspectives for the booming future uses of MBs.

A review on microfluidic-assisted nanoparticle synthesis, and their applications using multiscale simulation methods

Recent years have witnessed an increased interest in the development of nanoparticles (NPs) owing to their potential use in a wide variety of biomedical applications, including drug delivery, imaging agents, gene therapy, and vaccines, where recently, lipid nanoparticle mRNA-based vaccines were developed to prevent SARS-CoV-2 causing COVID-19. NPs typically fall into two broad categories: organic and inorganic. Organic NPs mainly include lipid-based and polymer-based nanoparticles, such as liposomes, solid lipid nanoparticles, polymersomes, dendrimers, and polymer micelles. Gold and silver NPs, iron oxide NPs, quantum dots, and carbon and silica-based nanomaterials make up the bulk of the inorganic NPs. These NPs are prepared using a variety of top-down and bottom-up approaches. Microfluidics provide an attractive synthesis alternative and is advantageous compared to the conventional bulk methods. The microfluidic mixing-based production methods offer better control in achieving the desired size, morphology, shape, size distribution, and surface properties of the synthesized NPs. The technology also exhibits excellent process repeatability, fast handling, less sample usage, and yields greater encapsulation efficiencies. In this article, we provide a comprehensive review of the microfluidic-based passive and active mixing techniques for NP synthesis, and their latest developments. Additionally, a summary of microfluidic devices used for NP production is presented. Nonetheless, despite significant advancements in the experimental procedures, complete details of a nanoparticle-based system cannot be deduced from the experiments alone, and thus, multiscale computer simulations are utilized to perform systematic investigations. The work also details the most common multiscale simulation methods and their advancements in unveiling critical mechanisms involved in nanoparticle synthesis and the interaction of nanoparticles with other entities, especially in biomedical and therapeutic systems. Finally, an analysis is provided on the challenges in microfluidics related to nanoparticle synthesis and applications, and the future perspectives, such as large-scale NP synthesis, and hybrid formulations and devices.

Shortwave Infrared Fluorofluorophores for Multicolor In Vivo Imaging

Developing chemical tools to detect and influence biological processes is a cornerstone of chemical biology. Here we combine two tools which rely on orthogonality- perfluorocarbons and multiplexed shortwave infrared (SWIR) fluorescence imaging- to visualize nanoemulsions in real time in living mice. Drawing inspiration from fluorous and SWIR fluorophore development, we prepared two SWIR-emissive, fluorous-soluble chromenylium polymethine dyes. These are the most red-shifted fluorous fluorophores- "fluorofluorophores"-to date. After characterizing the dyes, their utility was demonstrated by tracking perfluorocarbon nanoemulsion biodistribution in vivo. Using an excitation-multiplexed approach to image two variables simultaneously, we gained insight into the importance of size and surfactant identity on biodistribution.

Deformable and Disintegrable Multifunctional Integrated Polyprodrug Amphiphiles for Synergistic Phototherapy and Chemotherapy

Multimodal collaborative therapy has been recognized as one of the more effective means to eliminate tumors in the current biomedicine research field as compared with monotherapy. Among them, by taking advantage of its high-precision and controllability, phototherapy has become a mainstay of treatment. However, physical encapsulation of free photosensitive units within nanocarriers was one of the main implementations, which might inevitably result in the photosensitizer leakage and side effect. For this purpose, a kind of multifunctional integrated polyprodrug amphiphiles, P(PFO-IG-CPT)-PEG, were prepared by reversible addition-fragmentation chain transfer polymerization from polymerizable pentadecafluorooctan monomers, indocyanine green monomers, reduction-responsive camptothecin monomers, and acid-responsive PEG based methacrylate monomers (GMA(-OH/-PEG)). The resultant copolymers could self-assemble into spherical nanoparticles in water, performing size-deformability in acidic conditions and subsequent disintegration in reduction environment as demonstrated by in vitro experiments. Furthermore, an enhanced CPT release ratio and rate from nanoparticles could be achieved by a NIR irradiation due to the hyperthermia induced by the covalently linked IG moieties. Not only that, because of the sufficient O₂ content brought by PFO, the NIR light-triggered generation of ¹O₂ was also detected in cells. With the combination of CPT-guided chemotherapy as well as NIR light-guided photo-thermal and photodynamic therapies, fatal and irreversible damage to cancer cells was observed by cell experiments; the implanted tumor size in the mouse model was obviously shrunk upon receiving multimodal collaborative therapy. We speculate that such fabricated nanodiagnosis and treatment systems could meet the growing emergency for effective drug delivery, programmed and on-demand drug release, and multimodal integrated therapy.

A Psychrophilic GelMA: Breaking Technical and Immunological Barriers for Multimaterial High-Resolution 3D Bioprinting

The increasing demand for tissue replacement has encouraged scientists worldwide to focus on developing new biofabrication technologies. Multimaterials/cells printed with stringent resolutions are necessary to address the high complexity of tissues. Advanced inkjet 3D printing can use multimaterials and attain high resolution and complexity of printed structures. However, a decisive yet limiting aspect of translational 3D bioprinting is selecting the befitting material to be used as bioink; there is a complete lack of cytoactive bioinks with adequate rheological, mechanical, and reactive properties. This work strives to achieve the right balance between resolution and cell support through methacrylamide functionalization of a psychrophilic gelatin and new fluorosurfactants used to engineer a photo-cross-linkable and immunoevasive bioink. The syntonized parameters following optimal formulation conditions allow proficient printability in a PolyJet 3D printer comparable in resolution to a commercial synthetic ink (∼150 μm). The bioink formulation achieved the desired viability (∼80%) and proliferation of co-printed cells while demonstrating in vivo immune tolerance of printed structures. The practical usage of existing high-resolution 3D printing systems using a novel bioink is shown here, allowing 3D bioprinted structures with potentially unprecedented complexity.

Current perspectives of artificial oxygen carriers as red blood cell substitutes: a review of old to cutting-edge technologies using in vitro and in vivo assessments

Background

Several circumstances such as accidents, surgery, traumatic hemorrhagic shock, and other causalities cause major blood loss. Allogenic blood transfusion can be resuscitative for such conditions; however, it has numerous ambivalent effects, including supply shortage, needs for more time, cost for blood grouping, the possibility of spreading an infection, and short shelf-life. Hypoxia or ischemia causes heart failure, neurological problems, and organ damage in many patients. To address this emergent medical need for resuscitation and to treat hypoxic conditions as well as to enhance oxygen transportation, researchers aspire to achieve a robust technology aimed to develop safe and feasible red blood cell substitutes for effective oxygen transport.

Area covered

This review article provides an overview of the formulation, storage, shelf-life, clinical application, side effects, and current perspectives of artificial oxygen carriers (AOCs) as red blood cell substitutes. Moreover, the pre-clinical (in vitro and in vivo) assessments for the evaluation of the efficacy and safety of oxygen transport through AOCs are key considerations in this study. With the most significant technologies, hemoglobin- and perfluorocarbon-based oxygen carriers as well as other modern technologies, such as synthetically produced porphyrin-based AOCs and oxygen-carrying micro/nanobubbles, have also been elucidated.

Expert opinion

Both hemoglobin- and perfluorocarbon-based oxygen carriers are significant, despite having the latter acting as safeguards; they are cost-effective, facile formulations which penetrate small blood vessels and remove arterial blockages due to their nano-size. They also show better biocompatibility and longer half-life circulation than other similar technologies.

Low-boiling Point Perfluorocarbon Nanodroplets as Dual-Phase Dual-Modality MR/US Contrast Agent

Detection of bare gas microbubbles by magnetic resonance (MR) at low concentrations typically used in clinical contrast-ultrasound studies was recently demonstrated using hyperCEST. Despite the enhanced sensitivity achieved with hyperCEST, in vivo translation is challenging as on-resonance saturation of the gas-phase core of microbubbles consequently results in saturation of the gas-phase hyperpolarized 129 Xe within the lungs. Alternatively, microbubbles can be condensed into the liquid phase to form perfluorocarbon nanodroplets, where 129 Xe resonates at a chemical shift that is separated from the gas-phase signal in the lungs. For ultrasound applications, nanodroplets can be acoustically reverted back into their microbubble form to act as a phase-change contrast agent. Here, we show that low-boiling point perfluorocarbons, both in their liquid and gas form, generate phase-dependent hyperCEST contrast. Magnetic resonance detection of ultrasound-mediated phase transition demonstrates that these perfluorocarbons could be used as a dual-phase dual-modality MR/US contrast agent.

Taming Electrowetting Using Highly Concentrated Aqueous Solutions

Wetting of carbon surfaces is one of the most widespread, yet poorly understood, physical phenomena. Control over wetting properties underpins the operation of aqueous energy-storage devices and carbon-based filtration systems. Electrowetting, the variation in the contact angle with an applied potential, is the most straightforward way of introducing control over wetting. Here, we study electrowetting directly on graphitic surfaces with the use of aqueous electrolytes to show that reversible control of wetting can be achieved and quantitatively understood using models of the interfacial capacitance. We manifest that the use of highly concentrated aqueous electrolytes induces a fully symmetric and reversible wetting behavior without degradation of the substrate within the unprecedented potential window of 2.8 V. We demonstrate where the classical "Young-Lippmann" models apply, and break down, and discuss reasons for the latter, establishing relations among the applied bias, the electrolyte concentration, and the resultant contact angle. The approach is extended to electrowetting at the liquid|liquid interface, where a concentrated aqueous electrolyte drives reversibly the electrowetting response of an insulating organic phase with a significantly decreased potential threshold. In summary, this study highlights the beneficial effect of highly concentrated aqueous electrolytes on the electrowettability of carbon surfaces, being directly related to the performance of carbon-based aqueous energy-storage systems and electronic and microfluidic devices.

Design of Nanoparticles in Cancer Therapy Based on Tumor Microenvironment Properties

Cancer is one of the leading causes of death worldwide, and battling cancer has always been a challenging subject in medical sciences. All over the world, scientists from different fields of study try to gain a deeper knowledge about the biology and roots of cancer and, consequently, provide better strategies to fight against it. During the past few decades, nanoparticles (NPs) have attracted much attention for the delivery of therapeutic and diagnostic agents with high efficiency and reduced side effects in cancer treatment. Targeted and stimuli-sensitive nanoparticles have been widely studied for cancer therapy in recent years, and many more studies are ongoing. This review aims to provide a broad view of different nanoparticle systems with characteristics that allow them to target diverse properties of the tumor microenvironment (TME) from nanoparticles that can be activated and release their cargo due to the specific characteristics of the TME (such as low pH, redox, and hypoxia) to nanoparticles that can target different cellular and molecular targets of the present cell and molecules in the TME.

Smart biomaterials for enhancing cancer therapy by overcoming tumor hypoxia: a review

Hypoxia is a distinctive feature of most solid tumors due to insufficient oxygen supply of the abnormal vasculature, which cannot work with the demands of the fast proliferation of cancer cells. One of the main obstacles to limiting the efficacy of cancer medicines is tumor hypoxia. Thus, oxygen is a vital parameter for controlling the efficacy of different types of cancer therapy, such as chemotherapy (CT), photodynamic therapy (PDT), photothermal therapy (PTT), immunotherapy (IT), and radiotherapy (RT). Numerous technologies have attracted much attention for enhancing oxygen distribution in humans and improving the efficacy of cancer treatment. Such technologies include treatment with hyperbaric oxygen therapy (HBO), delivering oxygen by polysaccharides (e.g., cellulose, gelatin, alginate, and silk) and other biocompatible synthetic polymers (e.g., PMMA, PLA, PVA, PVP and PCL), decreasing oxygen consumption, producing oxygen in situ in tumors, and using polymeric systems as oxygen carriers. Herein, this review provides an overview of the relationship between hypoxia in tumor cells and its role in the limitation of different cancer therapies alongside the numerous strategies for oxygen delivery using polysaccharides and other biomaterials as carriers and for oxygen generation.