A Smart Nanotherapeutic Agent for in vitro and in vivo Reversal of Heavy‐Metal‐Induced Causality: Key Information from Optical Spectroscopy

Targeted Redox Balancing through Pulmonary Nanomedicine Delivery Reverses Oxidative Stress Induced Lung Inflammation

Non-invasive delivery of drugs is important for the reversal of respiratory diseases essentially by-passing metabolic pathways and targeting large surface area of drug absorption. Here, we study the inhalation of a redox nano medicine namely citrate functionalized Mn3O4 (C-Mn3O4) duly encapsulated in droplet evaporated aerosols for the balancing of oxidative stress generated by the exposure of Chromium (VI) ion, a potential lung carcinogenic agent. Our optical spectroscopic in-vitro experiments demonstrates the efficacy of redox balancing of the encapsulated nanoparticles (NP) for the maintenance of a homeostatic condition. The formation of Cr-NP complex as an excretion of the heavy metal is also demonstrated through optical spectroscopic and high resolution transmission optical microscopy (HRTEM). Our studies confirm the oxidative stress mitigation activity of the Cr-NP complex. A detailed immunological assay followed by histopathological studies and assessment of mitochondrial parameters in pre-clinical mice model with chromium (Cr) induced lung inflammation establishes the mechanism of drug action to be redox-buffering. Thus, localised delivery of C-Mn3O4 NPs in the respiratory tract via aerosols can act as an effective nanotherapeutic agent against oxidative stress induced lung inflammation.

Chitosan functionalized Mn3O4 nanoparticles counteracts ulcerative colitis in mice through modulation of cellular redox state

Recent findings suggest a key role for reactive oxygen species (ROS) in the pathogenesis and progression of ulcerative colitis (UC). Several studies have also highlighted the efficacy of citrate functionalized Mn3O4 nanoparticles as redox medicine against a number of ROS-mediated disorders. Here we show that synthesized nanoparticles consisting of chitosan functionalized tri-manganese tetroxide (Mn3O4) can restore redox balance in a mouse model of UC induced by dextran sulfate sodium (DSS). Our in-vitro characterization of the developed nanoparticle confirms critical electronic transitions in the nanoparticle to be important for the redox buffering activity in the animal model. A careful administration of the developed nanoparticle not only reduces inflammatory markers in the animals, but also reduces the mortality rate from the induced disease. This study provides a proof of concept for the use of nanomaterial with synergistic anti-inflammatory and redox buffering capacity to prevent and treat ulcerative colitis.

Chemoprevention of bilirubin encephalopathy with a nanoceutical agent

BACKGROUND

Targeted rapid degradation of bilirubin has the potential to thwart incipient bilirubin encephalopathy. We investigated a novel spinel-structured citrate-functionalized trimanganese tetroxide nanoparticle (C-Mn3O4 NP, the nanodrug) to degrade both systemic and neural bilirubin loads.

METHOD

Severe neonatal unconjugated hyperbilirubinemia (SNH) was induced in neonatal C57BL/6j mice model with phenylhydrazine (PHz) intoxication. Efficiency of the nanodrug on both in vivo bilirubin degradation and amelioration of bilirubin encephalopathy and associated neurobehavioral sequelae were evaluated.

RESULTS

Single oral dose (0.25 mg kg-1 bodyweight) of the nanodrug reduced both total serum bilirubin (TSB) and unconjugated bilirubin (UCB) in SNH rodents. Significant (p < 0.0001) UCB and TSB-degradation rates were reported within 4-8 h at 1.84 ± 0.26 and 2.19 ± 0.31 mg dL-1 h-1, respectively. Neural bilirubin load was decreased by 5.6 nmol g-1 (p = 0.0002) along with improved measures of neurobehavior, neuromotor movements, learning, and memory. Histopathological studies confirm that the nanodrug prevented neural cell reduction in Purkinje and substantia nigra regions, eosinophilic neurons, spongiosis, and cell shrinkage in SNH brain parenchyma. Brain oxidative status was maintained in nanodrug-treated SNH cohort. Pharmacokinetic data corroborated the bilirubin degradation rate with plasma nanodrug concentrations.

CONCLUSION

This study demonstrates the in vivo capacity of this novel nanodrug to reduce systemic and neural bilirubin load and reverse bilirubin-induced neurotoxicity. Further compilation of a drug-safety-dossier is warranted to translate this novel therapeutic chemopreventive approach to clinical settings.

IMPACT

None of the current pharmacotherapeutics treat severe neonatal hyperbilirubinemia (SNH) to prevent risks of neurotoxicity. In this preclinical study, a newly investigated nano-formulation, citrate-functionalized Mn3O4 nanoparticles (C-Mn3O4 NPs), exhibits bilirubin reduction properties in rodents. Chemopreventive properties of this nano-formulation demonstrate an efficacious, efficient agent that appears to be safe in these early studies. Translation of C-Mn3O4 NPs to prospective preclinical and clinical trials in appropriate in vivo models should be explored as a potential novel pharmacotherapy for SNH.

Functionalized Mn3 O4 Nanosheets with Photothermal, Photodynamic, and Oxidase-Like Activities Triggered by Low-Powered Near-Infrared Light for Synergetic Combating Multidrug-Resistant Bacterial Infections

Multidrug-resistant (MDR) pathogenic bacterial infections have become a major danger to public health. Synergetic therapy through multiple approaches is more powerful than the respective one alone, but has been rarely achieved in defeating MDR bacterial infections so far. Herein, indocyanine green-functionalized Mn₃ O₄ nanosheets are engineered as an efficient and safe antibacterial agent with photothermal, photodynamic, and oxidase-like activities, which display powerful ability in treating MDR bacterial infections. Therein, photothermal and photodynamic activities can be triggered by a single low-powered near-infrared laser (808 nm, 0.33 W cm^-2 ), resulting in the generation of localized hyperthermia (photothermal conversion efficiency, 67.5%) and singlet oxygen. Meanwhile, oxidase-like activity of this material further leads to the generation of hydroxyl radical as well as superoxide radical. Sheet-like structure with rough surfaces make them tends to adhere on bacterial surface and thus damage membrane system as well as influence bacterial metabolism. As a result, Gram-positive and Gram-negative bacteria can both be eradicated. Animal experiments further indicate that the functionalized Mn₃ O₄ nanosheets can effectively treat methicillin-resistant Staphylococcus aureus-infected wounds through the triple synergetic therapy. Moreover, toxicity evaluation in vitro and in vivo has proved the superior biosafety of this material, which is promising to apply in clinical anti-infective therapy.

In vitro and Microbiological Assay of Functionalized Hybrid Nanomaterials To Validate Their Efficacy in Nanotheranostics: A Combined Spectroscopic and Computational Study

Functionalized nanoparticles reveal new frontiers in therapeutics and diagnostics, simultaneously referred to as theranostics. Functionalization of an inorganic nanoparticle (NP) with an organic ligand determines the interaction of the functionalized NPs with various cellular components, leading to the desired therapeutic effect, while diminishing adverse side effects. Apart from the therapeutic effect of the nanoparticles, other physical properties of the organic-inorganic complex (nanohybrid) including fluorescence, X-ray or MRI contrast offer diagnosis of the anomalous target cell. In this study we functionalized Mn₃ O₄ NPs with organic citrate (C-Mn₃ O₄ ) and folic acid (FA-Mn₃ O₄ ) ligands and investigated their antimicrobial activities using Staphylococcus hominis as a model bacteria, which can be remediated through their membrane rupture. While high-resolution transmission microscopy (HR-TEM), XRD, DLS, absorbance and fluorescence spectroscopy were used for structural characterisation of the functionalised NPs, zeta potential measurements and temperature-dependent reactive oxygen speices (ROS) generation reveal their drug action. We used high-end density functional theory (DFT) calculations to rationalise the specificity of the drug action of the NPs. Picosecond-resolved FRET studies confirm the enhanced affinity of FA-Mn₃ O₄ to the bacteria relative to C-Mn₃ O₄ , leading to enhanced antimicrobial activity. We have shown that the functionalised nanoparticles offer significant X-ray contrast in in-vitro studies, indicating the FA-Mn₃ O₄ NPs to be a potential theranostic agent against bacterial infection.

Synthesis and characterization of a nano-formulation for long lasting sterilization effect

The current COVID-19 pandemic has increased the use of alcohol based hand sanitisers globally. These available alcohol based sanitisers cannot provide an antibacterial effect for an extended period of time, after the evaporation of ethanol. Hence, the need for a sanitiser with an anti-microbial activity combined with a long lasting effect is the need of the hour. In this study, we report the synthesis of a long lasting sanitiser from ozonated omega 9 fatty acid esters in an ethanolic medium. The formed vesicles made of the fatty acids have been characterized by DLS, Zeta potential, and time resolved fluorescence anisotropy studies. Ethanol although, provides an antibacterial effect, the effect is more pronounced in our prepared formulation owing to its high peroxide value that generates additional oxidative stress. Finally, this additional antimicrobial effect will have relevance in the current COVID-19 scenario in providing a long lasting hand sanitiser.

Redox Buffering Capacity of Nanomaterials as an Index of ROS-Based Therapeutics and Toxicity: A Preclinical Animal Study

Precise control of intracellular redox status, i.e., maintenance of the physiological level of reactive oxygen species (ROS) for mediating normal cellular functions (oxidative eustress) while evading the excess ROS stress (distress), is central to the concept of redox medicine. In this regard, engineered nanoparticles with unique ROS generation, transition, and depletion functions have the potential to be the choice of redox therapeutics. However, it is always challenging to estimate whether ROS-induced intracellular events are beneficial or deleterious to the cell. Here, we propose the concept of redox buffering capacity as a therapeutic index of engineered nanomaterials. As a steady redox state is maintained for normal functioning cells, we hypothesize that the ability of a nanomaterial to preserve this homeostatic condition will dictate its therapeutic efficacy. Additionally, the redox buffering capacity is expected to provide information about the nanoparticle toxicity. Here, using citrate-functionalized trimanganese tetroxide nanoparticles (C-Mn₃O₄ NPs) as a model nanosystem, we explored its redox buffering capacity in erythrocytes. Furthermore, we went on to study the chronic toxic effect (if any) of this nanomaterial in the animal model to co-relate with the experimentally estimated redox buffering capacity. This study could function as a framework for assessing the capability of a nanomaterial as redox medicine (whether maintains eustress or damages by creating distress), thus orienting its application and safety for clinical use.

Incorporation of a Biocompatible Nanozyme in Cellular Antioxidant Enzyme Cascade Reverses Huntington's Like Disorder in Preclinical Model

The potentiality of nano-enzymes in therapeutic use has directed contemporary research to develop a substitute for natural enzymes, which are suffering from several disadvantages including low stability, high cost, and difficulty in storage. However, inherent toxicity, inefficiency in the physiological milieu, and incompatibility to function in cellular enzyme networks limit the therapeutic use of nanozymes in living systems. Here, it is shown that citrate functionalized manganese-based biocompatible nanoscale material (C-Mn₃ O₄ NP) efficiently mimics glutathione peroxidase (GPx) enzyme in the physiological milieu and easily incorporates into the cellular multienzyme cascade for H₂ O₂ scavenging. A detailed computational study reveals the mechanism of the nanozyme action. The in vivo therapeutic efficacy of C-Mn₃ O₄ nanozyme is further established in a preclinical animal model of Huntington's disease (HD), a prevalent progressive neurodegenerative disorder, which has no effective medication to date. Management of HD in preclinical animal trial using a biocompatible (non-toxic) nanozyme as a part of the metabolic network may uncover a new paradigm in nanozyme based therapeutic strategy.

Combating Essential Metal Toxicity: Key Information from Optical Spectroscopy

Chelation therapy is one of the most effective and widely accepted methods of treatment to reduce metal toxicity caused by an excess amount of essential metals. Essential minerals play an important role in maintaining healthy human physiology. However, the presence of an excess amount of such essential metals can cause cell injury, which finally leads to severe life-threatening diseases. Chelating complexes can efficiently capture the targeted metal and can easily be excreted from the body. Commonly utilized metal chelators have major side effects including long-term damage to some organs, which has pointed out the need of less harmful biocompatible chelating agents. In this work, we have investigated the iron chelating property of curcumin through various spectroscopic tools by synthesizing and characterizing the iron-curcumin (Fe-Cur) complex. We have also investigated whether the synthesized materials are able to retain their antioxidant activity after the chelation of a substantial amount of metal ion. Our study unravels the improved antioxidant activity of the synthesized chelate complex. We further demonstrate that the proposed complex generates no significant reactive oxygen species (ROS) under dark conditions, which makes it a promising candidate for chelation therapy of iron toxicity. Femtosecond-resolved fluorescence studies further provide insight into the mechanism of activity of the new complex where electron transfer from ligand to metal has been observed prominently. Thus, the Fe-Cur complex has a potential to act as a dual activity medicine for excretion of toxic metal ions via chelation and as a therapeutic agent of oxidative stress caused by the metal ion as well.