Antioxidant carbon particles improve cerebrovascular dysfunction following traumatic brain injury

Oxidation of Hydrogen Sulfide to Polysulfide and Thiosulfate by a Carbon Nanozyme: Therapeutic Implications with an Emphasis on Down Syndrome

Hydrogen sulfide (H2 S) is a noxious, potentially poisonous, but necessary gas produced from sulfur metabolism in humans. In Down Syndrome (DS), the production of H2 S is elevated and associated with degraded mitochondrial function. Therefore, removing H2 S from the body as a stable oxide could be an approach to reducing the deleterious effects of H2 S in DS. In this report we describe the catalytic oxidation of hydrogen sulfide (H2 S) to polysulfides (HS2+n - ) and thiosulfate (S2 O3 2- ) by poly(ethylene glycol) hydrophilic carbon clusters (PEG-HCCs) and poly(ethylene glycol) oxidized activated charcoal (PEG-OACs), examples of oxidized carbon nanozymes (OCNs). We show that OCNs oxidize H2 S to polysulfides and S2 O3 2- in a dose-dependent manner. The reaction is dependent on O2 and the presence of quinone groups on the OCNs. In DS donor lymphocytes we found that OCNs increased polysulfide production, proliferation, and afforded protection against additional toxic levels of H2 S compared to untreated DS lymphocytes. Finally, in Dp16 and Ts65DN murine models of DS, we found that OCNs restored osteoclast differentiation. This new action suggests potential facile translation into the clinic for conditions involving excess H2 S exemplified by DS.

Oxidized Activated Charcoal Nanozymes: Synthesis, and Optimization for In Vitro and In Vivo Bioactivity for Traumatic Brain Injury

Carbon-based superoxide dismutase (SOD) mimetic nanozymes have recently been employed as promising antioxidant nanotherapeutics due to their distinct properties. The structural features responsible for the efficacy of these nanomaterials as antioxidants are, however, poorly understood. Here, the process-structure-property-performance properties of coconut-derived oxidized activated charcoal (cOAC) nano-SOD mimetics are studied by analyzing how modifications to the nanomaterial's synthesis impact the size, as well as the elemental and electrochemical properties of the particles. These properties are then correlated to the in vitro antioxidant bioactivity of poly(ethylene glycol)-functionalized cOACs (PEG-cOAC). Chemical oxidative treatment methods that afford smaller, more homogeneous cOAC nanoparticles with higher levels of quinone functionalization show enhanced protection against oxidative damage in bEnd.3 murine endothelioma cells. In an in vivo rat model of mild traumatic brain injury (mTBI) and oxidative vascular injury, PEG-cOACs restore cerebral perfusion rapidly to the same extent as the former nanotube-derived PEG-hydrophilic carbon clusters (PEG-HCCs) with a single intravenous injection. These findings provide a deeper understanding of how carbon nanozyme syntheses can be tailored for improved antioxidant bioactivity, and set the stage for translation of medical applications.

Molybdenum Nanodots for Acute Lung Injury Therapy

Acute respiratory disease syndrome (ARDS) is a common critical disease with high morbidity and mortality rates, yet specific and effective treatments for it are currently lacking. ARDS was especially apparent and rampant during the COVID-19 pandemic. Excess reactive oxygen species (ROS) production and an uncontrolled inflammatory response play a critical role in the disease progression of ARDS. Herein, we developed molybdenum nanodots (MNDs) as a functional nanomaterial with ultrasmall size, good biocompatibility, and excellent ROS scavenging ability for the treatment of acute lung injury (ALI). MNDs, which were administered intratracheally, significantly ameliorated lung oxidative stress, inflammatory response, protein permeability, and histological severity in ALI mice without inducing any safety issues. Importantly, transcriptomics analysis indicated that MNDs protected lung tissues by inhibiting the activation of the Nod-like receptor protein 3 (NLRP3)-dependent pyroptotic pathway. This work presents a promising therapeutic agent for patients suffering from ARDS.

Reactive X (where X = O, N, S, C, Cl, Br, and I) species nanomedicine

Reactive oxygen, nitrogen, sulfur, carbonyl, chlorine, bromine, and iodine species (RXS, where X = O, N, S, C, Cl, Br, and I) have important roles in various normal physiological processes and act as essential regulators of cell metabolism; their inherent biological activities govern cell signaling, immune balance, and tissue homeostasis. However, an imbalance between RXS production and consumption will induce the occurrence and development of various diseases. Due to the considerable progress of nanomedicine, a variety of nanosystems that can regulate RXS has been rationally designed and engineered for restoring RXS balance to halt the pathological processes of different diseases. The invention of radical-regulating nanomaterials creates the possibility of intriguing projects for disease treatment and promotes advances in nanomedicine. In this comprehensive review, we summarize, discuss, and highlight very-recent advances in RXS-based nanomedicine for versatile disease treatments. This review particularly focuses on the types and pathological effects of these reactive species and explores the biological effects of RXS-based nanomaterials, accompanied by a discussion and the outlook of the challenges faced and future clinical translations of RXS nanomedicines.

Graphene nanoplatelets and other 2D-materials as protective means against the fading of coloured inks, dyes and paints

The present work demonstrates the ability of graphene nanoplatelets (GNPs) and other two-dimensional materials (2DMs) like tungsten disulfide (WS2), molybdenum disulfide (MoS2) and hexagonal boron nitride (hBN) to act as protective barriers against the fading of architectural paints and also inks/paints used in art. The results present a new approach for improving the lightfastness of colours of artworks and painted indoor/outdoor wall surfaces taking advantage of the remarkable properties of 2DMs. As shown herein, commercial inks and architectural paints of different colours doped with graphene nanoplatelets (GNPs), graphene oxide (GO), reduced graphene oxide (rGO) and other 2DMs, exhibit a superior resistance to fading under ultraviolet radiation or even under exposure to visible light. A spectroscopic study on these inks and dyes reveals that the peaks which are characteristic of the colour pigments are less affected from aging/fading when the GNPs and the other 2DMs are present. The protection mechanism for the GNPs and the other 2DMs differs. For GNPs, mainly their high surface area which leads to free radicals scavenging (especially hydroxyl radicals), and secondarily their UV absorption, are responsible for their protection effects, while for GO, a transition to rGO structures and consequently to 'smart' paints can be observed after the performed aging routes. In this way, the paint gets improved by time preventing or slowing its own fading and decolorization. For the other 2DMs, the transition-metal dichalcogenides performed better than hBN, even though they all absorb in the UV region. This can be ascribed to the facts that the formers also absorb in the visible, while hBN does not, while most importantly, they can trap reactive oxygen species (ROS) and corrosive gases in their structure as opposed to hBN. By conducting colorimetric measurements, we have discovered that the lifetime of the as-developed 2DM-doped inks and paints can be extended by up to ∼40%.

Role of TREM2 in the Development of Neurodegenerative Diseases After Traumatic Brain Injury

Traumatic brain injury (TBI) has been found as the primary cause of morbidity and disability worldwide, which has posed a significant social and economic burden. The first stage of TBI produces brain edema, axonal damage, and hypoxia, thus having an effect on the blood-brain barrier function, promoting inflammatory responses, and increasing oxidative stress. Patients with TBI are more likely to develop post-traumatic epilepsy, behavioral issues, as well as mental illnesses. The long-term effects arising from TBI have aroused rising attention over the past few years. Microglia in the brain can express the triggering receptor expressed on myeloid cells 2 (TREM2), which is a single transmembrane receptor pertaining to the immunoglobulin superfamily. The receptor has been correlated with a number of neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and other relevant diseases. In this review, it is demonstrated that TREM2 is promising to serve as a neuroprotective factor for neurodegenerative disorders following TBI by modulating the function of microglial cells. Accordingly, it has potential avenues for TREM2-related therapies to improve long-term recovery after TBI.

A Simple Route to the Complexation of Lutein with Reduced Graphene Oxide Nanocarriers and Antioxidant Protection Against Blue Light

BACKGROUND

The excellent physicochemical properties of graphene-based materials, including graphene oxide (GO) and reduced GO (rGO), offer significant technological potential as multifunctional nanomaterials in biomedical fields. Lutein is a type of carotenoid that forms human macular pigments in the retina, where it inhibits harmful blue light and contributes to the strengthening of the antioxidant defense of retinal pigment epithelium cells.

METHODS

Synthesis of the Lutein-rGO (Lu-rGO) complex was carried out for the optimized concentration. Then characterization of material was analyzed through ultraviolet-visible spectrophotometer (UV-Vis spectra), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). Antioxidant activity of Lu-rGO complex was measured by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2.2-diphenyl-1-picrylhydrazyl (DPPH), glutathione (GSH) oxidation assay. Then, oxidative stress induction by blue light and analyzed intracellular reactive oxygen species (ROS).

RESULTS AND CONCLUSION

Based on the FT-IR measurement, the reduction efficiency defined by area was found to be 87.3%, the ID/IG ratio of 0.98 demonstrated by the Lu-rGO complex in the Raman spectrum was slightly higher than that of the original GO. The exhibited significant decrease in the peak intensities of the oxygen functional groups of the XPS spectra of the Lu-rGO complex was observed compared with the GO. In the TEM image for the Lu-rGO complex, folded and wrinkled nanostructures over the lutein-covered rGO surface were evidenced by tight molecular binding. The Lu-rGO complex provided superior DPPH and ABTS radical scavenging activity than GO and lutein alone, and the oxidation of GSH was suppressed. It was confirmed that the content of intracellular ROS and lysosomes, increased by blue light, was reduced after treatment with the Lu-rGO complex on ARPE-19 cells. In summary, graphene-based nanocarriers could function as preventative antioxidants during photochemical ROS generation based on the mechanism of antioxidant action.

Nanoparticles-mediated emerging approaches for effective treatment of ischemic stroke

Ischemic stroke leads to high disability and mortality. The limited delivery efficiency of most therapeutic substances is a major challenge for effective treatment of ischemic stroke. Inspired by the prominent merit of nanoscale particles in brain targeting and blood-brain barrier (BBB) penetration, various functional nanoparticles have been designed as promising drug delivery platforms that are expected to improve the therapeutic effect of ischemic stroke. Based on the complex pathological mechanisms of ischemic stroke, this review outline and summarize the rationally designed nanoparticles-mediated emerging approaches for effective treatment of ischemic stroke, including recanalization therapy, neuroprotection therapy, and combination therapy. On this bases, the potentials and challenges of nanoparticles in the treatment of ischemic stroke are revealed, and new thoughts and perspectives are proposed for the design of feasible nanoparticles for effective treatment of ischemic stroke.

Rational Design of Nanomaterials for Various Radiation-Induced Diseases Prevention and Treatment

Radiation treatments often unfavorably damage neighboring healthy organs and cause a series of radiation sequelae, such as radiation-induced hematopoietic system diseases, radiation-induced gastrointestinal diseases, radiation-induced lung diseases, and radiation-induced skin diseases. Recently, emerging nanomaterials have exhibited good superiority for these radiation-induced disease treatments. Given this background, the rational design principle of nanomaterials, which helps to optimize the therapeutic efficiency, has been an increasing need. Consequently, it is of great significance to perform a systematic summarization of the advances in this field, which can trigger the development of new high-performance nanoradioprotectors with drug efficiency maximization. Herein, this review highlights the advances and perspectives in the rational design of nanomaterials for preventing and treating various common radiation-induced diseases. Furthermore, the sources, clinical symptoms, and pathogenesis/injury mechanisms of these radiation-induced diseases will also be introduced. Furthermore, current challenges and directions for future efforts in this field are also discussed.

Nanomedicine for Acute Brain Injuries: Insight from Decades of Cancer Nanomedicine

Acute brain injuries such as traumatic brain injury and stroke affect 85 million people a year worldwide, and many survivors suffer from long-term physical, cognitive, or psychosocial impairments. There are few FDA-approved therapies that are effective at preventing, halting, or ameliorating the state of disease in the brain after acute brain injury. To address this unmet need, one potential strategy is to leverage the unique physical and biological properties of nanomaterials. Decades of cancer nanomedicine research can serve as a blueprint for innovation in brain injury nanomedicines, both to emulate the successes and also to avoid potential pitfalls. In this review, we discuss how shared disease physiology between cancer and acute brain injuries can inform the design of novel nanomedicines for acute brain injuries. These disease hallmarks include dysregulated vasculature, an altered microenvironment, and changes in the immune system. We discuss several nanomaterial strategies that can be engineered to exploit these disease hallmarks, for example, passive accumulation, active targeting of disease-associated signals, bioresponsive designs that are "smart", and immune interactions.

Chitosan nanocarrier for FTY720 enhanced delivery retards Parkinson's disease via PP2A-EzH2 signaling in vitro and ex vivo

Parkinson's disease (PD) develops due to oxidative stress, mitochondrial aberrations, posttranslational modification, and α-Synuclein (α-Syn) aggregation. The α-synucleinopathy is attributed to phosphorylation and aggregation of α-Syn. A strategy to degrade or reduce phosphorylated protein paves the way to develop PD therapy. Hence, the neuroprotective efficiency of PP2A (Protein phosphatase 2) activator FTY720, loaded chitosan nanoformulation has been evaluated in vitro and ex vivo experimental PD models. Bio-compatible chitosan-based nanocarriers have been utilized to enhance the bio-availability and neuroprotective effect of FTY720. The neuroprotective effect of characterized nanoformulation was determined by the downregulation of PD hallmark phospho-serine 129 (pSer129) α-Syn, with anti-oxidative and anti-inflammatory potentials. The neuroprotective mechanism uncovered novel physical interaction of PP2A and polycomb group of protein Enhancer of zeste homolog 2 to mediate ubiquitination and degradation of agglomerated pSer129 α-Syn. Indeed, this study establishes the neuroprotective potential of chitosan based FTY720 nanoformulations by PP2A mediated epigenetic regulation for PD prevention.

Recent advances in ultrathin two-dimensional materials and biomedical applications for reactive oxygen species generation and scavenging

Graphene and graphene-like two-dimensional (2D) nanomaterials, such as black phosphorus (BP), transition metal carbides/carbonitrides (MXene) and transition metal dichalcogenides (TMD), have been extensively studied in recent years due to their unique physical and chemical properties. With atomic-scale thickness, these 2D materials and their derivatives can react with ROS and even scavenge ROS in the dark. With excellent biocompatibility and biosafety, they show great application potential in the antioxidant field and ROS detection for diagnosis. They can also generate ROS under light and be applied in antibacterial, photodynamic therapy (PDT), and other biomedical fields. Understanding the degradation mechanism of 2D nanomaterials by ROS generated under ambient conditions is crucial to developing air stable devices and expanding their application ranges. In this review, we summarize recent advances in 2D materials with a focus on the relationship between their intrinsic structure and the ROS scavenging or generating ability. We have also highlighted important guidelines for the design and synthesis of highly efficient ROS scavenging or generating 2D materials along with their biomedical applications.

Redox-Responsive Nanobiomaterials-Based Therapeutics for Neurodegenerative Diseases

Redox regulation has recently been proposed as a critical intracellular mechanism affecting cell survival, proliferation, and differentiation. Redox homeostasis has also been implicated in a variety of degenerative neurological disorders such as Parkinson's and Alzheimer's disease. In fact, it is hypothesized that markers of oxidative stress precede pathologic lesions in Alzheimer's disease and other neurodegenerative diseases. Several therapeutic approaches have been suggested so far to improve the endogenous defense against oxidative stress and its harmful effects. Among such approaches, the use of artificial antioxidant systems has gained increased popularity as an effective strategy. Nanoscale drug delivery systems loaded with enzymes, bioinspired catalytic nanoparticles and other nanomaterials have emerged as promising candidates. The development of degradable hydrogels scaffolds with antioxidant effects could also enable scientists to positively influence cell fate. This current review summarizes nanobiomaterial-based approaches for redox regulation and their potential applications as central nervous system neurodegenerative disease treatments.

Ultrasmall Mixed Eu-Gd Oxide Nanoparticles for Multimodal Fluorescence and Magnetic Resonance Imaging of Passive Accumulation and Retention in TBI

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. TBI can have a long-term impact on the quality of life for survivors of all ages. However, there remains no approved treatment that improves outcomes following TBI, which is partially due to poor delivery of therapies into the brain. Therefore, there is a significant unmet need to develop more effective delivery strategies that increase the accumulation and retention of potentially efficacious treatments in the injured brain. Recent work has revealed that nanoparticles (NPs) may offer a promising approach for site-specific delivery; however, a detailed understanding of the specific NP properties that promote brain accumulation and retention are still being developed. Multimodal imaging plays a vital role in the understanding of physicochemical properties that initiate the uptake and accumulation of NPs in the brain at both high spatial (e.g., fluorescence imaging) and temporal (e.g., magnetic resonance imaging, MRI) frequency. However, many NP systems that are currently used in TBI only provide contrast in a single imaging modality limiting the imaging data that can be obtained, and those that offer multimodal imaging capabilities have complicated multistep synthesis methods. Therefore, the goal of this work was to develop an ultrasmall NP with simple fabrication capable of multimodal imaging. Here, we describe the development, characterization, accumulation, and retention of poly(ethylene glycol) (PEG)-coated europium-gadolinium (Eu-Gd) mixed magnetic NPs (MNPs) in a controlled cortical impact mouse model of TBI. We find that these NPs having an ultrasmall core size of 2 nm and a small hydrodynamic size of 13.5 nm can be detected in both fluorescence and MR imaging modalities and rapidly accumulate and are retained in injured brain parenchyma. These NPs should allow for further testing of NP physicochemical properties that promote accumulation and retention in TBI and other disease models.

Antioxidant Graphene Oxide Nanoribbon as a Novel Whitening Agent Inhibits Microphthalmia-Associated Transcription Factor-Related Melanogenesis Mechanism

In the melanin synthesis process, oxidative reactions play an essential role, and it is a good strategy to inhibit melanin production by reducing oxidative stress. Fullerene and its derivatives, or the complexes, were considered as strong free-radical scavengers, and we further applied multilayered sp² nanocarbons to discover melanin synthesis inhibitory mechanisms. In the present study, we used novel nanomaterials, such as multiwalled carbon nanotubes (MWCNTs), short-type MWCNTs, graphene oxide nanoribbons (GONRs), and short-type GONRs, as anti-oxidative agents to regulate melanin production. The results showed that GONRs had better anti-oxidative capabilities in intracellular and extracellular oxidative stress analysis platforms than others. We proposed that GONRs have oxygen-containing functional groups. In the 2',7'-dichlorodihydrofluorescein diacetate assay, we found out GONR could chelate metal ions to scavenge reactive oxygen species. In the molecular insight view, we observed that these nanomaterials downregulated the melanin synthesis by decreasing microphthalmia-associated transcription factor-related gene expressions, and there were similar consequences in protein expressions. To sum up, GONRs is a potential agent as a novel antioxidant and skin-whitening cosmetology material.

Pervasive Genomic Damage in Experimental Intracerebral Hemorrhage: Therapeutic Potential of a Mechanistic-Based Carbon Nanoparticle

Therapy for intracerebral hemorrhage (ICH) remains elusive, in part dependent on the severity of the hemorrhage itself as well as multiple deleterious effects of blood and its breakdown products such as hemin and free iron. While oxidative injury and genomic damage have been seen following ICH, the details of this injury and implications remain unclear. Here, we discovered that, while free iron produced mostly reactive oxygen species (ROS)-related single-strand DNA breaks, hemin unexpectedly induced rapid and persistent nuclear and mitochondrial double-strand breaks (DSBs) in neuronal and endothelial cell genomes and in mouse brains following experimental ICH comparable to that seen with γ radiation and DNA-complexing chemotherapies. Potentially as a result of persistent DSBs and the DNA damage response, hemin also resulted in senescence phenotype in cultured neurons and endothelial cells. Subsequent resistance to ferroptosis reported in other senescent cell types was also observed here in neurons. While antioxidant therapy prevented senescence, cells became sensitized to ferroptosis. To address both senescence and resistance to ferroptosis, we synthesized a modified, catalytic, and rapidly internalized carbon nanomaterial, poly(ethylene glycol)-conjugated hydrophilic carbon clusters (PEG-HCC) by covalently bonding the iron chelator, deferoxamine (DEF). This multifunctional nanoparticle, DEF-HCC-PEG, protected cells from both senescence and ferroptosis and restored nuclear and mitochondrial genome integrity in vitro and in vivo. We thus describe a potential molecular mechanism of hemin/iron-induced toxicity in ICH that involves a rapid induction of DSBs, senescence, and the consequent resistance to ferroptosis and provide a mechanistic-based combinatorial therapeutic strategy.

Antioxidants and Nanotechnology: Promises and Limits of Potentially Disruptive Approaches in the Treatment of Central Nervous System Diseases

Many central nervous system (CNS) diseases are still incurable and only symptomatic treatments are available. Oxidative stress is suggested to be a common hallmark, being able to cause and exacerbate the neuronal cell dysfunctions at the basis of these pathologies, such as mitochondrial impairments, accumulation of misfolded proteins, cell membrane damages, and apoptosis induction. Several antioxidant compounds are tested as potential countermeasures for CNS disorders, but their efficacy is often hindered by the loss of antioxidant properties due to enzymatic degradation, low bioavailability, poor water solubility, and insufficient blood-brain barrier crossing efficiency. To overcome the limitations of antioxidant molecules, exploitation of nanostructures, either for their delivery or with inherent antioxidant properties, is proposed. In this review, after a brief discussion concerning the role of the blood-brain barrier in the CNS and the involvement of oxidative stress in some neurodegenerative diseases, the most interesting research concerning the use of nano-antioxidants is introduced and discussed, focusing on the synthesis procedures, functionalization strategies, in vitro and in vivo tests, and on recent clinical trials.

Use of a bioengineered antioxidant in mouse models of metabolic syndrome

Background: Oxidative stress has been implicated in metabolic syndrome (MetS); however, antioxidants such as vitamin E have had limited success in the clinic. This prompts the question of what effects amore potent antioxidant might produce. A prime candidate is the recently developed bioengineered antioxidant, poly(ethylene glycol)-functionalizedhydrophilic carbon clusters (PEG-HCCs), which are capable of neutralizing the reactive oxygen species (ROS) superoxide anion and hydroxyl radical at10⁶/molecule of PEG-HCC. In this project, we tested the potential of PEG-HCCs as a possible therapeutic for MetS.Results: PEG-HCC treatment lessened lipid peroxidation, aspartate aminotransferase levels, non-fastingblood glucose levels, and JNK phosphorylation inob/ob mice. PEG-HCC-treated WT mice had an increased response to insulin by insulin tolerance tests and adecrease in blood glucose by glucose tolerance tests. These effects were not observed in HFD-fed mice, regardless of treatment. PEG-HCCs were observed in the interstitial space of liver, spleen, skeletal muscle, and adipose tissue. No significant difference was shown in gluconeogenesis or inflammatory gene expression between treatment and dietary groups.Expert Opinion: PEG-HCCs improved some parameters of disease possibly due to a resulting increase in peripheral insulin sensitivity. However, additional studies are needed to elucidate how PEG-HCCsare producing these effects.

Reactive Oxygen Species-Induced Aggregation of Nanozymes for Neuron Injury

Nanozymes show excellent enzyme activity and robust catalytic properties, but the targeting capability to disease organs is limited because of lack of specificity. Herein, we developed an ultrasmall (∼3 nm) organic nanozyme that can gradually aggregate under a reactive oxygen species (ROS)-rich environment via a spontaneous reaction, namely, ROS-induced aggregation. The size of nanozymes is 75 and 100 times higher than the original size under ^•OH and H₂O₂ environments without losing enzyme activity. In vitro experiments confirm that nanozymes prefer to aggregate in mitochondria under ROS-rich conditions. Importantly, the nanozymes show in situ ROS-induced aggregation in the brain, ∼9 times higher uptake than ordinary nanozymes, indicating their potential for treating ROS-related diseases in the central nervous system.

Carbon dot targeting to nitrogen signaling molecules for inhibiting neuronal death

Ultrasmall carbon dot with targeting ability to nitrogen signaling molecules inhibit neuronal death by regulating the activity of endogenous enzymes.

Nanotherapeutic modulation of excitotoxicity and oxidative stress in acute brain injury

Excitotoxicity is a primary pathological process that occurs during stroke, traumatic brain injury (TBI), and global brain ischemia such as perinatal asphyxia. Excitotoxicity is triggered by an overabundance of excitatory neurotransmitters within the synapse, causing a detrimental cascade of excessive sodium and calcium influx, generation of reactive oxygen species, mitochondrial damage, and ultimately cell death. There are multiple potential points of intervention to combat excitotoxicity and downstream oxidative stress, yet there are currently no therapeutics clinically approved for this specific purpose. For a therapeutic to be effective against excitotoxicity, the therapeutic must accumulate at the disease site at the appropriate concentration at the right time. Nanotechnology can provide benefits for therapeutic delivery, including overcoming physiological obstacles such as the blood–brain barrier, protect cargo from degradation, and provide controlled release of a drug. This review evaluates the use of nano-based therapeutics to combat excitotoxicity in stroke, TBI, and hypoxia–ischemia with an emphasis on mitigating oxidative stress, and consideration of the path forward toward clinical translation.

A Role for Nanoparticles in Treating Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the main causes of disability in children and young adults, as well as a significant concern for elderly individuals. Depending on the severity, TBI can have a long-term impact on the quality of life for survivors of all ages. The primary brain injury can result in severe disability or fatality, and secondary brain damage can increase the complexities in cellular, inflammatory, neurochemical, and metabolic changes in the brain, which can last decades post-injury. Thus, survival from a TBI is often accompanied by lifelong disabilities. Despite the significant morbidity, mortality, and economic loss, there are still no effective treatment options demonstrating an improved outcome in a large multi-center Phase III trial, which can be partially attributed to poor target engagement of delivered therapeutics. Thus, there is a significant unmet need to develop more effective delivery strategies to overcome the biological barriers that would otherwise inhibit transport of materials into the brain to prevent the secondary long-term damage associated with TBI. The complex pathology of TBI involving the blood-brain barrier (BBB) has limited the development of effective therapeutics and diagnostics. Therefore, it is of great importance to develop novel strategies to target the BBB. The leaky BBB caused by a TBI may provide opportunities for therapeutic delivery via nanoparticles (NP). The focus of this review is to provide a survey of NP-based strategies employed in preclinical models of TBI and to provide insights for improved NP based diagnostic or treatment approaches. Both passive and active delivery of various NPs for TBI are discussed. Finally, potential therapeutic targets where improved NP-mediated delivery could increase target engagement are identified with the overall goal of providing insight into open opportunities for NP researchers to begin research in TBI.

Nanozyme: new horizons for responsive biomedical applications

Nanozymes are nanomaterial-based artificial enzymes. By effectively mimicking catalytic sites of natural enzymes or harboring multivalent elements for reactions, nanozyme systems have successfully served as direct surrogates of traditional enzymes for catalysis. With the rapid development and ever-deepening understanding of nanotechnology, nanozymes offer higher catalytic stability, ease of modification and lower manufacturing cost than protein enzymes. Additionally, nanozymes possess inherent nanomaterial properties, providing not only a simple substitute of enzymes but also a multimodal platform interfacing complex biologic environments. Recent extensive research has focused on designing various nanozyme systems that are responsive to one or multiple substrates by tailored means. Catalytic activities of nanozymes can be regulated by pH, H2O2 and glutathione concentrations and levels of oxygenation in different microenvironments. Moreover, nanozymes can be remotely-controlled via different stimuli, including a magnetic field, light, ultrasound, and heat. Collectively, these factors can be adjusted to maximize the diagnostic and therapeutic efficacies of different diseases in biomedical settings. Therefore, by integrating the catalytic property and inherent nanomaterial nature of nanozyme systems, we anticipate that stimuli-responsive nanozymes will open up new horizons for diagnosis, treatment, and theranostics.

Carbogenic Nanozyme with Ultrahigh Reactive Nitrogen Species Selectivity for Traumatic Brain Injury

Reactive oxygen and nitrogen species (RONS), especially reactive nitrogen species (RNS) are intermediate products during incidence of nervous system diseases, showing continuous damage for traumatic brain injury (TBI). Here, we developed a carbogenic nanozyme, which shows an antioxidant activity 12 times higher than ascorbic acid (AA) and behaves as multienzyme mimetics. Importantly, the nanozyme exhibits an ultrahigh scavenging efficiency (∼16 times higher than AA) toward highly active RNS, such as ^•NO and ONOO^- as well as traditional reactive oxygen species (ROS) including O₂^•-, H₂O₂, and ^•OH. In vitro experiments show that neuron cells injured by H₂O₂ or lipopolysaccharide can be significantly recovered after carbogenic nanozyme treatment via scavenging all kinds of RONS. Moreover, the carbogenic nanozyme can serve as various enzyme mimetics and eliminate the harmful peroxide and glutathione disulfide from injured mice, demonstrating its potential as a therapeutic for acute TBI.

Chlorine-Doped Graphene Quantum Dots with Enhanced Anti- and Pro-Oxidant Properties

Production or elimination of highly reactive oxygen species is critical in antioxidant, photodynamic, therapeutic, and antibacterial applications. Recent studies have demonstrated that graphene quantum dots (GQDs) possess anti- and pro-oxidant properties simultaneously. However, their efficiency is low. Here, we report chlorine-doped GQDs (Cl-GQDs) with a tunable Cl doping amount and improved anti- and pro-oxidant activities. The scavenging performance and the free radical-produced efficiency of Cl-GQDs are about 7-fold and 3-fold, respectively, higher than those of the undoped GQDs. Meanwhile, Cl-GQDs are considered to be promising for antibacterial applications because of their enhanced singlet oxygen generating ability. We hope that this study could provide a new strategy to develop nanomaterials for application in the anti- and pro-oxidant field.

Catalytic oxidation and reduction reactions of hydrophilic carbon clusters with NADH and cytochrome C: features of an electron transport nanozyme

Previously, our group reported on the promising efficacy of poly(ethylene glycol)-hydrophilic carbon clusters (PEG-HCCs) to work as broadly active and high capacity antioxidants in brain ischemia and injury models including stroke and traumatic brain injury coupled with hemorrhagic shock. PEG-HCCs are a carbon nanomaterial derived from harsh oxidation of single wall carbon nanotubes and covalently modified with poly(ethylene glycol). They retain no tubular remnants and are composed of a highly oxidized carbon core functionalized with epoxy, peroxyl, quinone, ketone, carboxylate, and hydroxyl groups. HCCs are the redox active carbon core of PEG-HCCs, which have a broad reduction potential range starting at +200 mV and extending to -2 V. Here we describe a new property of these materials: the ability to catalytically transfer electrons between key surrogates and proteins of the mitochondrial electron transport complex in a catalytic fashion consistent with the concept of a nanozyme. The estimated reduction potential of PEG-HCCs is similar to that of ubiquinone and they enabled the catalytic transfer of electrons from low reduction potential species to higher reduction electron transport complex constituents. PEG-HCCs accelerated the reduction of resazurin (a test indicator of mitochondrial viability) and cytochrome c by NADH and ascorbic acid in solution. Kinetic experiments suggested a transient tertiary complex. Electron paramagnetic resonance demonstrated NADH increased the magnitude of PEG-HCCs' intrinsic radical, which then reduced upon subsequent addition of cytochrome c or resazurin. Deconvolution microscopy identified PEG-HCCs in close proximity to mitochondria after brief incubation with cultured SHSY-5Y human neuroblastoma cells. Compared to methylene blue (MB), considered a prototypical small molecule electron transport shuttle, PEG-HCCs were more protective against toxic effects of hydrogen peroxide in vitro and did not demonstrate impaired cell viability as did MB. PEG-HCCs were protective in vitro when cells were exposed to sodium cyanide, a mitochondrial complex IV poison. Because mitochondria are a major source of free radicals in pathology, we suggest that this newly described nanozyme action helps explain their in vivo efficacy in a range of injury models. These findings may also extend their use to mitochondrial disorders.

Functional and Structural Improvement with a Catalytic Carbon Nano-Antioxidant in Experimental Traumatic Brain Injury Complicated by Hypotension and Resuscitation

Hypotension worsens outcome after all severities of traumatic brain injury (TBI), with loss of cerebral autoregulation being a potential contributor. Previously, we demonstrated that intravenous injection of a high capacity catalytic antioxidant, poly(ethylene)glycol conjugated hydrophilic carbon clusters (PEG-HCCs) rapidly restored cerebral perfusion and acutely restored brain oxidative balance in a TBI model complicated by hemorrhagic hypotension without evidence of toxicity. Here, we tested whether these acute effects translated into behavioral and structural benefit. TBI was generated by a cortical contusion impactor in 38 Long Evans rats, followed by blood withdrawal to a target mean arterial pressure of 40 mm Hg. PEG-HCC (2 mg/kg) or diluent was injected intravenously 80 min later at the onset of blood resuscitation followed by another injection 2 h later (doses determined in prior studies). Performance on beam walking (performed on days 1-5) and Morris water maze (MWM) (performed on days 11-15) was tested, and lesion size was determined at the termination. PEG-HCC treatment nearly completely prevented motor dysfunction (p < 0.001 vs. diluent), improved MWM performance (p < 0.001; treatment vs. time interaction) and reduced lesion size by 61% (p = 0.054). Here we show that treatment with PEG-HCCs at a clinically realistic time point (onset of resuscitation) prevented a major portion of the neurological dysfunction induced in this TBI model, and that PEG-HCCs are candidates for additional study as a potential therapeutic agent.

Inducible lung epithelial resistance requires multisource reactive oxygen species generation to protect against bacterial infections

Pneumonia remains a global health threat, in part due to expanding categories of susceptible individuals and increasing prevalence of antibiotic resistant pathogens. However, therapeutic stimulation of the lungs’ mucosal defenses by inhaled exposure to a synergistic combination of Toll-like receptor (TLR) agonists known as Pam2-ODN promotes mouse survival of pneumonia caused by a wide array of pathogens. This inducible resistance to pneumonia relies on intact lung epithelial TLR signaling, and inducible protection against viral pathogens has recently been shown to require increased production of epithelial reactive oxygen species (ROS) from multiple epithelial ROS generators. To determine whether similar mechanisms contribute to inducible antibacterial responses, the current work investigates the role of ROS in therapeutically-stimulated protection against Pseudomonas aerugnosa challenges. Inhaled Pam2-ODN treatment one day before infection prevented hemorrhagic lung cytotoxicity and mouse death in a manner that correlated with reduction in bacterial burden. The bacterial killing effect of Pam2-ODN was recapitulated in isolated mouse and human lung epithelial cells, and the protection correlated with inducible epithelial generation of ROS. Scavenging or targeted blockade of ROS production from either dual oxidase or mitochondrial sources resulted in near complete loss of Pam2-ODN-induced bacterial killing, whereas deficiency of induced antimicrobial peptides had little effect. These findings support a central role for multisource epithelial ROS in inducible resistance against a bacterial pathogen and provide mechanistic insights into means to protect vulnerable patients against lethal infections.

Comprehensive Characterization of Cerebrovascular Dysfunction in Blast Traumatic Brain Injury Using Photoacoustic Microscopy

Blast traumatic brain injury (bTBI) is a leading contributor to combat-related injuries and death. Although substantial emphasis has been placed on blast-induced neuronal and axonal injuries, co-existing dysfunctions in the cerebral vasculature, particularly the microvasculature, remain poorly understood. Here, we studied blast-induced cerebrovascular dysfunctions in a rat model of bTBI (blast overpressure: 187.8 ± 18.3 kPa). Using photoacoustic microscopy (PAM), we quantified changes in cerebral hemodynamics and metabolism-including blood perfusion, oxygenation, flow, oxygen extraction fraction, and the metabolic rate of oxygen-4 h post-injury. Moreover, we assessed the effect of blast exposure on cerebrovascular reactivity (CVR) to vasodilatory stimulation. With vessel segmentation, we extracted these changes at the single-vessel level, revealing their dependence on vessel type (i.e., artery vs. vein) and diameter. We found that bTBI at this pressure level did not induce pronounced baseline changes in cerebrovascular diameter, blood perfusion, oxygenation, flow, oxygen extraction, and metabolism, except for a slight sO₂ increase in small veins (<45 μm) and blood flow increase in large veins (≥45 μm). In contrast, this blast exposure almost abolished CVR, including arterial dilation, flow upregulation, and venous sO₂ increase. This study is the most comprehensive assessment of cerebrovascular structure and physiology in response to blast exposure to date. The observed impairment in CVR can potentially cause cognitive decline due to the mismatch between cognitive metabolic demands and vessel's ability to dynamically respond to meet the demands. Also, the impaired CVR can lead to increased vulnerability of the brain to metabolic insults, including hypoxia and ischemia.

Optimizing oxygen functional groups in graphene quantum dots for improved antioxidant mechanism

The development of new antioxidants with quick absorbance of free radicals and excellent biocompatibility has drawn intensive attention in recent years. Graphene quantum dots (GQDs) seemed to be one of the most promising antioxidants because of their appropriate antioxidant activity, unique structure, excellent biocompatibility, and low toxicity. However, the relatively low antioxidant activity in comparison with inorganic semiconductor materials and unclear antioxidant mechanism limited their application in cells. In this paper, we further explored their antioxidant mechanism by focusing on the relationship between antioxidant activity and surface oxygen functional groups. The total oxygen fraction was controlled by post-preparation reduction using NaBH₄ and the type of oxygen functional groups was adjusted by free radicals during the preparation of GQDs. The degree of reduction and content of surface oxygen groups were determined by X-ray photoelectron spectroscopy (XPS), and the antioxidant activity was obtained by scavenging of 1,1-diphenyl-2-picryl-hydrazyl (DPPH˙) and hydroxyl (˙OH) free radicals. Based on the analysis of XPS, Raman, and Fourier-transform infrared (FT-IR) spectra, the relationship between antioxidant activity and the surface oxygen groups of GQDs was obtained, and the antioxidant mechanism of GQDs was revealed with a particular specification of each oxygen group in the antioxidant activity of GQDs, meanwhile, the biocompatibility of GQDs has been demonstrated by cytotoxicity tests. We hope that our results will provide a new insight into a complete antioxidant mechanism of GQDs.

Scavenging of reactive oxygen and nitrogen species with nanomaterials

Reactive oxygen and nitrogen species (RONS) are essential for normal physiological processes and play important roles in cell signaling, immunity, and tissue homeostasis. However, excess radical species are implicated in the development and augmented pathogenesis of various diseases. Several antioxidants may restore the chemical balance, but their use is limited by disappointing results of clinical trials. Nanoparticles are an attractive therapeutic alternative because they can change the biodistribution profile of antioxidants, and possess intrinsic ability to scavenge RONS. Herein, we review the types of RONS, how they are implicated in several diseases, and the types of nanoparticles with inherent antioxidant capability, their mechanisms of action, and their biological applications.

Antioxidant efficacy of chitosan/graphene functionalized superparamagnetic iron oxide nanoparticles

The antioxidant potential of superparamagnetic iron oxide nanoparticles functionalized with chitosan and graphene were examined in the present work. Coprecipitation technique was followed for the synthesis of iron oxide nanoparticles. Graphene-iron oxide nanocomposites were synthesized by mechanical mixing followed by the heat treatment at moderate temperature. The chitosan coated iron oxide nanoparticles were prepared by dispersing nanoparticles in chitosan solution. The nanoparticles/nanocomposites were characterized using XRD, SEM, TEM and HAADF-STEM for phase structure, morphology and elemental analysis. The superparamagnetic behavior of nanoparticles/nanocomposites were confirmed by magnetic measurements using vibrating sample magnetometry. Antioxidant efficacy of these nanoparticles/nanocomposites were investigated in terms of free radical scavenging and reducing potential using an array of in vitro assay system. Ferric reducing antioxidant power (FRAP) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) were used for the antioxidant capacity. The investigation suggests that the graphene improves the antiradical response of iron oxide nanoparticles at higher concentration which is almost comparable to the ascorbic acid used as standard.

Controlling carbon nanodot fluorescence for optical biosensing

In this work we report on the optical properties of specific synthetic carbon nano-dots (CDs) and their suitability for the development of optical biosensors. We examine the photoluminescence behavior of these CDs under different conditions, in their native form, as well as when conjugated to the catalytic protein glucose oxidase (GOx) for the construction of optical glucose biosensors. The effect of pH and hydrogen peroxide on the observed spectra is examined as the basis for the biosensor development. The CDs examined here have inherent surface amino functional groups which allow for easy conjugation to biomolecules via EDC-NHS, providing a well defined platform for biosensing applications. We conclude that the well controlled, stable, and highly efficient fluorescence behavior of the CDs in solution or in conjugate, provides the grounds for this class of materials to be used in a variety of arrangements for the development of optical and optoelectrochemical detection systems.

Blood-brainbarrier disruption dictates nanoparticle accumulation following experimental brain injury

Clinically, traumatic brain injury (TBI) results in complex heterogeneous pathology that cannot be recapitulated in single pre-clinical animal model. Therefore, we focused on evaluating utility of nanoparticle (NP)-based therapeutics following three diffuse-TBI models: mildclosed-head injury (mCHI), repetitive-mCHI and midline-fluid percussion injury (FPI). We hypothesized that NP accumulation after diffuse TBI correlates directly with blood-brainbarrier permeability. Mice received PEGylated-NP cocktail (20-500 nm) (intravenously) after single- or repetitive-(1 impact/day, 5 consecutive days) CHI (immediately) and midline-FPI (1 h, 3 h and 6 h). NPs circulated for 1 h before perfusion/brain extraction. NP accumulation was analyzed using fluorescent microscopy in brain regions vulnerable to neuropathology. Minimal/no NP accumulation after mCHI/RmCHI was observed. In contrast, midlineFPI resulted in significant peak accumulation of up to 500 nm NP at 3 h post-injury compared to sham, 1 h, and 6 h groups in the cortex. Therefore, our study provides the groundwork for feasibility of NP-delivery based on NPinjection time and NPsize after mCHI/RmCHI and midline-FPI.

Inducible Lung Epithelial Resistance Requires Multisource Reactive Oxygen Species Generation To Protect against Viral Infections

Viral pneumonias cause profound worldwide morbidity, necessitating novel strategies to prevent and treat these potentially lethal infections. Stimulation of intrinsic lung defenses via inhalation of synergistically acting Toll-like receptor (TLR) agonists protects mice broadly against pneumonia, including otherwise-lethal viral infections, providing a potential opportunity to mitigate infectious threats. As intact lung epithelial TLR signaling is required for the inducible resistance and as these cells are the principal targets of many respiratory viruses, the capacity of lung epithelial cells to be therapeutically manipulated to function as autonomous antiviral effectors was investigated. Our work revealed that mouse and human lung epithelial cells could be stimulated to generate robust antiviral responses that both reduce viral burden and enhance survival of isolated cells and intact animals. The antiviral protection required concurrent induction of epithelial reactive oxygen species (ROS) from both mitochondrial and dual oxidase sources, although neither type I interferon enrichment nor type I interferon signaling was required for the inducible protection. Taken together, these findings establish the sufficiency of lung epithelial cells to generate therapeutically inducible antiviral responses, reveal novel antiviral roles for ROS, provide mechanistic insights into inducible resistance, and may provide an opportunity to protect patients from viral pneumonia during periods of peak vulnerability.IMPORTANCE Viruses are the most commonly identified causes of pneumonia and inflict unacceptable morbidity, despite currently available therapies. While lung epithelial cells are principal targets of respiratory viruses, they have also been recently shown to contribute importantly to therapeutically inducible antimicrobial responses. This work finds that lung cells can be stimulated to protect themselves against viral challenges, even in the absence of leukocytes, both reducing viral burden and improving survival. Further, it was found that the protection occurs via unexpected induction of reactive oxygen species (ROS) from spatially segregated sources without reliance on type I interferon signaling. Coordinated multisource ROS generation has not previously been described against viruses, nor has ROS generation been reported for epithelial cells against any pathogen. Thus, these findings extend the potential clinical applications for the strategy of inducible resistance to protect vulnerable people against viral infections and also provide new insights into the capacity of lung cells to protect against infections via novel ROS-dependent mechanisms.

Efficacy of Novel Carbon Nanoparticle Antioxidant Therapy in a Severe Model of Reversible Middle Cerebral Artery Stroke in Acutely Hyperglycemic Rats

INTRODUCTION

While oxidative stress can be measured during transient cerebral ischemia, antioxidant therapies for ischemic stroke have been clinically unsuccessful. Many antioxidants are limited in their range and/or capacity for quenching radicals and can generate toxic intermediates overwhelming depleted endogenous protection. We developed a new antioxidant class, 40 nm × 2 nm carbon nanoparticles, hydrophilic carbon clusters, conjugated to poly(ethylene glycol) termed PEG-HCCs. These particles are high-capacity superoxide dismutase mimics, are effective against hydroxyl radical, and restore the balance between nitric oxide and superoxide in the vasculature. Here, we report the effects of PEG-HCCs administered during reperfusion after transient middle cerebral artery occlusion (tMCAO) by suture in the rat under hyperglycemic conditions. Hyperglycemia occurs in one-third of stroke patients and worsens clinical outcome. In animal models, this worsening occurs largely by accelerating elaboration of reactive oxygen species (ROS) during reperfusion.

METHODS

PEG-HCCs were studied for their protective ability against hydrogen peroxide in b.End3 brain endothelial cell line and E17 primary cortical neuron cultures. In vivo, hyperglycemia was induced by streptozotocin injection 2 days before tMCAO. 58 Male Sprague-Dawley rats were analyzed. They were injected IV with PBS or PEG-HCCs (4 mg/kg 2×) at the time of recanalization after either 90- or 120-min occlusion. Rats were survived for up to 3 days, and infarct volume characteristics and neurological functional outcome (modified Bederson Score) were assessed.

RESULTS

PEG-HCCs were protective against hydrogen peroxide in both culture models. In vivo improvement was found after PEG-HCCs with 90-min ischemia with reduction in infarct size (42%), hemisphere swelling (46%), hemorrhage score (53%), and improvement in Bederson score (70%) (p = 0.068-0.001). Early high mortality in the 2-h in the PBS control group precluded detailed analysis, but a trend was found in improvement in all factors, e.g., reduction in infarct volume (48%; p = 0.034) and a 56% improvement in Bederson score (p = 0.055) with PEG-HCCs.

CONCLUSION

This nano-antioxidant showed some improvement in several outcome measures in a severe model of tMCAO when administered at a clinically relevant time point. Long-term studies and additional models are required to assess potential for clinical use, especially for patients hyperglycemic at the time of their stroke, as these patients have the worst outcomes.

Immunostimulatory CpG on Carbon Nanotubes Selectively Inhibits Migration of Brain Tumor Cells

Even when treated with aggressive current therapies, patients with glioblastoma usually survive less than two years and exhibit a high rate of recurrence. CpG is an oligonucleotide that activates the innate immune system via Toll-like receptor 9 (TLR9) activation. Injection of CpG into glioblastoma tumors showed promise as an immunotherapy in mouse models but proved disappointing in human trials. One aspect of glioma that is not addressed by CpG therapy alone is the highly invasive nature of glioma cells, which is associated with resistance to radiation and chemotherapy. Here, we demonstrate that single-walled carbon nanotubes noncovalently functionalized with CpG (SWNT/CpG), which retain the immunostimulatory property of the CpG, selectively inhibit the migration of glioma cells and not macrophages without affecting cell viability or proliferation. SWNT/CpG also selectively decreased NF-κB activation in glioma cells, while activating macrophages by induction of the TLR9/NF-κB pathway, as we have previously reported. The migration inhibition of glioma cells was correlated with selective reduction of intracellular levels of reactive oxygen species (ROS), suggesting that an antioxidant-based mechanism mediates the observed effects. To the best of our knowledge, SWNT/CpG is the first nanomaterial that inhibits the migration of cancer cells while stimulating the immune system.

Nitrogen-Doped Carbon Nanodots-Ionogels: Preparation, Characterization, and Radical Scavenging Activity

Hybrid diimidazolium-based ionogels were obtained by dispersing nitrogen-doped carbon nanodots (NCNDs) in ionic liquid (IL) solutions and by using dicationic organic salts as gelators. The properties of the NCND-ionogels were studied in terms of thermal stability, mechanical strength, morphology, rheological, and microscopic analyses. Insights into the formation of the hybrid soft material were attained from kinetics of sol-gel phase transition and from estimating the size of the aggregates, obtained from opacity and resonance light-scattering measurements. We demonstrate that, on one hand, NCNDs were able to favor the gel formation both in the presence of gelating and nongelating ILs. On the other hand, the gelatinous matrix retains and, in some cases, improves the properties of NCNDs. The NCND-ionogels showed the typical fluorescence emission of the carbon dots and a notable antiradical activity, with higher efficiency as compared to the single components. The presented hybrid materials hold great promise for topical applications in antioxidant fields.

Transfer of Dyes and Drugs into Cells Using EGFR-Targeted Nanosyringes

Selective targeting of drug loaded nanovectors to specific epitopes highly expressed on the surface of cancer cells is a goal for nanotechnologists. We have modified our previously described PEGylated-hydrophilic carbon clusters (PEG-HCCs) so that the epidermal growth factor receptor (EGFR) binding peptide, GE11, is attached using click chemistry at the end of each PEG. The resulting nanosyringe, Pep_EGFR-PEG-HCC, can be loaded with a wide range of hydrophobic drugs and dyes. We show that, both in vitro and in vivo, this payload can be delivered to cancer cells expressing EGFR. We can observe the activation of EGFR and track the normal physiological internalization and recycling/signaling pathways of this tyrosine kinase following binding of Pep_EGFR-PEG-HCC. We also demonstrate the competitive binding of the nanosyringe to EGFR with its normal activator, EGF, as well as observing the colocalization of the nanosyringe with clathrin, the coated pit integral protein. The internalization of the drug/dye loaded nanosyringe can be inhibited by using anti-EGFR antibodies, the drug erlotinib, or Pitstop-1, the clathrin coated pit formation specific inhibitor. To further demonstrate the specificity of the drug loaded nanovectors, we demonstrated that, in both flank and intracranial xenograft mouse models, dye delivery is highly specific to tumors and no other tissues. Finally, using nanosyringes loaded with esterase sensitive fluorescein diacetate, we demonstrated that the drug payloads can be in vivo delivered to the cytosol of cancer cells within the mouse brain.

Nanoparticle-Based Therapeutics for Brain Injury

Brain injuries affect a large patient population with major physical and emotional suffering for patients and their relatives; at a significant cost to the society. Effective diagnostic and therapeutic options available for brain injuries are limited by the complex brain injury pathology involving blood-brain barrier (BBB). Brain injuries, including ischemic stroke and brain trauma, initiate BBB opening for a short period of time, which is followed by a second reopening for an extended time. The leaky BBB and/or the alterations in the receptor expression on BBB may provide opportunities for therapeutic delivery via nanoparticles (NPs). The approaches for therapeutic interventions via NP delivery are aimed at salvaging the pericontusional/penumbra area for possible neuroprotection and neurovascular unit preservation. The focus of this progress report is to provide a survey of NP strategies employed in cerebral ischemia and brain trauma and finally provide insights for improved NP-based diagnostic/treatment approaches.

Lutein and Zeaxanthin Influence Brain Function in Older Adults: A Randomized Controlled Trial

OBJECTIVES

The present study constitutes the first randomized controlled trial to investigate the relation of lutein (L) and zeaxanthin (Z) to brain function using functional magnetic resonance imaging (fMRI). It was hypothesized that L and Z supplementation in older adults would enhance neural efficiency (i.e., reduce activation) and cognitive performance on a verbal learning task relative to placebo.

METHODS

A total of 44 community-dwelling older adults (mean age=72 years) were randomly assigned to receive either placebo or L+Z supplementation (12 mg/daily) for 1 year. Neurocognitive performance was assessed at baseline and post-intervention on an fMRI-adapted task involving learning and recalling word pairs. Imaging contrasts of blood-oxygen-level-dependent (BOLD) signal were created by subtracting active control trials from learning and recall trials. A flexible factorial model was employed to investigate the expected group (placebo vs. supplement) by time (baseline vs. post-intervention) interaction in pre-specified regions-of-interest.

RESULTS

L and Z appeared to buffer cognitive decline on the verbal learning task (Cohen's d=.84). Significant interactions during learning were observed in left dorsolateral prefrontal cortex and anterior cingulate cortex (p < .05, family-wise-error corrected). However, these effects were in the direction of increased rather than decreased BOLD signal. Although the omnibus interaction was not significant during recall, within-group contrasts revealed significant increases in left prefrontal activation in the supplement group only.

CONCLUSIONS

L and Z supplementation appears to benefit neurocognitive function by enhancing cerebral perfusion, even if consumed for a discrete period of time in late life. (JINS, 2018, 24, 77-90).

Antioxidant nanomaterials in advanced diagnoses and treatments of ischemia reperfusion injuries

Organ ischemia with inadequate oxygen supply followed by reperfusion (which initiates a complex of inflammatory responses and oxidative stress) occurs in different clinical conditions and surgical procedures including stroke, myocardial infarction, limb ischemia, renal failure, organ transplantation, free-tissue-transfer, cardiopulmonary bypass, and vascular surgery. Even though pharmacological treatments protect against experimental ischemia reperfusion (I/R) injury, there has not been enough success in their application for patient benefits. The main hurdles in the treatment of I/R injury are the lack of diagnosis tools for understanding the complicated chains of I/R-induced signaling events, especially in the acute phase after ischemia, determining the affected regions of the tissue over time, and then, targeting and safe delivery of antioxidants, drugs, peptides, genes and cells to the areas requiring treatment. Besides the innate antioxidant and free radical scavenging properties, some nanoparticles also show higher flexibility in drug delivery and imaging. This review highlights three main approaches in nanoparticle-mediated targeting of I/R injury: nanoparticles (1) as antioxidants for reducing tissue oxidative stress, (2) for targeted delivery of therapeutic agents to the ischemic regions or cells, and (3) for imaging I/R injury at the molecular, cellular or tissue level and monitoring its evolution using contrasts induced by nanoparticles. These approaches can also be combined to realize so called theranostics for providing simultaneous diagnosis of ischemic regions and treatments by targeted delivery.

Redox-active nanomaterials for nanomedicine applications

Nanomedicine utilizes the remarkable properties of nanomaterials for the diagnosis, treatment, and prevention of disease. Many of these nanomaterials have been shown to have robust antioxidative properties, potentially functioning as strong scavengers of reactive oxygen species. Conversely, several nanomaterials have also been shown to promote the generation of reactive oxygen species, which may precipitate the onset of oxidative stress, a state that is thought to contribute to the development of a variety of adverse conditions. As such, the impacts of nanomaterials on biological entities are often associated with and influenced by their specific redox properties. In this review, we overview several classes of nanomaterials that have been or projected to be used across a wide range of biomedical applications, with discussion focusing on their unique redox properties. Nanomaterials examined include iron, cerium, and titanium metal oxide nanoparticles, gold, silver, and selenium nanoparticles, and various nanoscale carbon allotropes such as graphene, carbon nanotubes, fullerenes, and their derivatives/variations. Principal topics of discussion include the chemical mechanisms by which the nanomaterials directly interact with biological entities and the biological cascades that are thus indirectly impacted. Selected case studies highlighting the redox properties of nanomaterials and how they affect biological responses are used to exemplify the biologically-relevant redox mechanisms for each of the described nanomaterials.