Luminescent lanthanide complexes for reactive oxygen species biosensing and possible application in Alzheimer's diseases

Luminescent Lanthanides in Biorelated Applications: From Molecules to Nanoparticles and Diagnostic Probes to Therapeutics

Lanthanides are particularly effective in their clinical applications in magnetic resonance imaging and diagnostic assays. They have open-shell 4f electrons that give rise to characteristic narrow, line-like emission which is unique from other fluorescent probes in biological systems. Lanthanide luminescence signal offers selection of detection pathways based on the choice of the ion from the visible to the near-infrared with long luminescence lifetimes that lend themselves to time-resolved measurements for optical multiplexing detection schemes and novel bioimaging applications. The delivery of lanthanide agents in cells allows localized bioresponsive activity for novel therapies. Detection in the near-infrared region of the spectrum coupled with technological advances in microscopies opens new avenues for deep-tissue imaging and surgical interventions. This review focuses on the different ways in which lanthanide luminescence can be exploited in nucleic acid and enzyme detection, anion recognition, cellular imaging, tissue imaging, and photoinduced therapeutic applications. We have focused on the hierarchy of designs that include luminescent lanthanides as probes in biology considering coordination complexes, multimetallic lanthanide systems to metal-organic frameworks and nanoparticles highlighting the different strategies in downshifting, and upconversion revealing some of the opportunities and challenges that offer potential for further development in the field.

The emerging role of oxygen redox in pathological progression of disorders

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington disease, pose serious threats to human health, leading to substantial economic burdens on society and families. Despite extensive research, the underlying mechanisms driving these diseases remain incompletely understood, impeding effective diagnosis and treatment. In recent years, growing evidence has highlighted the crucial role of oxidative stress in the pathogenesis of various neurodegenerative diseases. However, there is still a lack of comprehensive reviews that systematically summarize the impact of mitochondrial oxidative stress on neurodegenerative diseases. This review aims to address this gap by summarizing the molecular mechanisms by which mitochondrial oxidative stress promotes the initiation and progression of neurodegenerative disorders. Furthermore, it discusses the potential of antioxidant-based therapeutic strategies for the treatment of these diseases. By shedding light on the role of mitochondrial oxidative stress in neurodegenerative diseases, this review not only serves as a valuable reference for further research on the disease mechanisms, but also offers novel perspectives for the treatment of these disorders.

Benzenesulfonamide as a novel, pharmaceutical small molecule inhibitor on Aβ gene expression and oxidative stress in Alzheimer's Wistar rats

Alzheimer's disease (AD) is the most prevalent acute neurodegenerative disease described by memory loss and other cognitive functions. Benzenesulfonamide, a novel, potent, and small organic molecule, was synthesized to investigate its effects on the levels of oxidative biomarkers (GPx, ROS, and MDA) and expression of beta-amyloid peptides (Aβ40 and Aβ42) in the pathology of AD. The results were compared with the rivastigmine drug. Applying benzenesulfonamide to Alzheimer's-induced Wistar rats showed a significant increase in the level of oxidative biomarkers (GPx, ROS, and MDA) in both the brain and blood serum as well as amyloid-β40 and 42 gene expressions. Therefore, benzenesulfonamide could be considered a novel therapeutic agent against AD.

Guluronic acid can inhibit copper(II) and amyloid - β peptide coordination and reduce copper-related reactive oxygen species formation associated with Alzheimer's disease

Copper-related reactive oxygen species (ROS) formation can lead to neuropathologic degradation associated with Alzheimer's disease (AD) according to amyloid cascade hypothesis. A complexing agent that can selectively chelate with copper ions and capture copper ions from the complex formed by copper ions and amyloid-β (Cu - Aβ complex) may be available in reducing ROS formation. Herein, we described applications of guluronic acid (GA), a natural oligosaccharide complexing agent obtained from enzymatic hydrolysis of brown algae, in reducing copper-related ROS formation. UV-vis absorption spectra demonstrated the coordination between GA and Cu(II). Ascorbic acid consumption and coumarin-3-carboxylic acid fluorescence assays confirmed the viability of GA in reducing ROS formation in solutions containing other metal ions and Aβ. Fluorescence kinetics, DPPH radical clearance and high resolution X - ray photoelectron spectroscopy results revealed the reductivity of GA. Human liver hepatocellular carcinoma (HepG2) cell viability demonstrated the biocompatibility of GA at concentrations lower than 320 μM. Cytotoxic results of human neuroblastoma (SH-SY5Y) cells verified that GA can inhibit copper-related ROS damage in neuronal cells. Our findings, combined with the advantages of marine drugs, make GA a promising candidate in reducing copper-related ROS formation associated with AD therapy.

Redox signaling and metabolism in Alzheimer's disease

Reduction and oxidation reactions are essential for biochemical processes. They are part of metabolic pathways and signal transduction. Reactive oxygen species (ROS) as second messengers and oxidative modifications of cysteinyl (Cys) residues are key to transduce and translate intracellular and intercellular signals. Dysregulation of cellular redox signaling is known as oxidative distress, which has been linked to various pathologies, including neurodegeneration. Alzheimer's disease (AD) is a neurodegenerative pathology linked to both, abnormal amyloid precursor protein (APP) processing, generating Aβ peptide, and Tau hyperphosphorylation and aggregation. Signs of oxidative distress in AD include: increase of ROS (H2O2, O2 •-), decrease of the levels or activities of antioxidant enzymes, abnormal oxidation of macromolecules related to elevated Aβ production, and changes in mitochondrial homeostasis linked to Tau phosphorylation. Interestingly, Cys residues present in APP form disulfide bonds that are important for intermolecular interactions and might be involved in the aggregation of Aβ. Moreover, two Cys residues in some Tau isoforms have been shown to be essential for Tau stabilization and its interaction with microtubules. Future research will show the complexities of Tau, its interactome, and the role that Cys residues play in the progression of AD. The specific modification of cysteinyl residues in redox signaling is also tightly connected to the regulation of various metabolic pathways. Many of these pathways have been found to be altered in AD, even at very early stages. In order to analyze the complex changes and underlying mechanisms, several AD models have been developed, including animal models, 2D and 3D cell culture, and ex-vivo studies of patient samples. The use of these models along with innovative, new redox analysis techniques are key to further understand the importance of the redox component in Alzheimer's disease and the identification of new therapeutic targets in the future.

Regenerative Activities of ROS-Modulating Trace Metals in Subcutaneously Implanted Biodegradable Cryogel

Divalent trace metals (TM), especially copper (Cu), cobalt (Co) and zinc (Zn), are recognized as essential microelements for tissue homeostasis and regeneration. To achieve a balance between therapeutic activity and safety of administered TMs, effective gel formulations of TMs with elucidated regenerative mechanisms are required. We studied in vitro and in vivo effects of biodegradable macroporous cryogels doped with Cu, Co or Zn in a controllable manner. The extracellular ROS generation by metal dopants was assessed and compared with the intracellular effect of soluble TMs. The stimulating ability of TMs in the cryogels for cell proliferation, differentiation and cytokine/growth factor biosynthesis was characterized using HSF and HUVEC primary human cells. Multiple responses of host tissues to the TM-doped cryogels upon subcutaneous implantation were characterized taking into account the rate of biodegradation, production of HIF-1α/matrix metalloproteinases and the appearance of immune cells. Cu and Zn dopants did not disturb the intact skin organization while inducing specific stimulating effects on different skin structures, including vasculature, whereas Co dopant caused a significant reorganization of skin layers, the appearance of multinucleated giant cells, along with intense angiogenesis in the dermis. The results specify and compare the prooxidant and regenerative potential of Cu, Co and Zn-doped biodegradable cryogels and are of particular interest for the development of advanced bioinductive hydrogel materials for controlling angiogenesis and soft tissue growth.

Biomedical Applications of Lanthanide Nanomaterials, for Imaging, Sensing and Therapy

The application of nanomaterials made of rare earth elements within biomedical sciences continues to make significant progress. The rare earth elements, also called the lanthanides, play an essential role in modern life through materials and electronics. As we learn more about their utility, function, and underlying physics, we can contemplate extending their applications to biomedicine. This particularly applies to diagnosis and radiation therapy due to their relatively unique features, such as an ultra-wide Stokes shift in the luminescence, variable magnetism and potentially tunable properties, due to the library of lanthanides available and their multivalent oxidation state chemistry. The ability to prepare nanomaterials of relatively smaller sizes has increased the likelihood of use in vivo. In this review, we summarize the different emerging applications of nanoparticles with rare earth elements as the host or doped elements for biomedical applications in the past three to four years, especially in the area of imaging and disease diagnosis. Researchers have made progress in utilizing surfactants and polymers to modify the surface of lanthanide nanoparticles to enhance biocompatibility. At the same time, specific antibodies and proteins can also be conjugated to these nanoparticles to increase targeting efficiency for specific tumor models. Finally, in the near-infrared II imaging window, lanthanide nanoparticles have been shown to exhibit extraordinary bright emission, which is an exciting development for image-guided surgery.