In Vitro and In Vivo Electrochemical Measurement of Reactive Oxygen Species After Treatment with Anticancer Drugs

Light-Responsive Pt(IV) Prodrugs with Controlled Photoactivation and Low Dark Toxicity

Light-induced release of cisplatin from Pt(IV) prodrugs represents a promising approach for precise control over the antiproliferative activity of Pt-based chemotherapeutic drugs. This method has the potential to overcome crucial drawbacks of conventional cisplatin therapy, such as high general toxicity toward healthy organs and tissues. Herein, we report two Pt(IV) prodrugs with BODIPY-based photoactive ligands Pt-1 and Pt-2, which were designed using carbamate and triazole linkers, respectively. Both prodrugs demonstrated the ability to release cisplatin under blue light irradiation without the requirement of an external reducing agent. Dicarboxylated Pt-2 prodrug turned out to be more stable in the dark and more sensitive to light than its monocarbamate Pt-1 counterpart; these observations were explained using DFT calculations. The investigation of the photoreduction mechanism of Pt-1 and Pt-2 prodrugs using DFT modeling and ΔG0 PET estimation suggests that the photoinduced electron transfer from the singlet excited state of the BODIPY axial ligand to the Pt(IV) center is the key step in the light-induced release of cisplatin from the complexes. Cytotoxicity studies demonstrated that both prodrugs were nontoxic in the dark and toxic to MCF-7 cells under low-dose irradiation with blue light, and the observed effect was solely due to the cisplatin release from the Pt(IV) prodrugs. Our research presents an elegant synthetic approach to light-activated Pt(IV) prodrugs and presents findings that may contribute to the future rational design of photoactivatable Pt(IV) prodrugs.

Tri-mode Responses to Reactive Oxygen Species In Vivo by Chiral Vanadium-Based Nanoparticles

Reactive oxygen species (ROS) are closely associated with the redox balance of the physiological environment, and monitoring ROS can aid in the early diagnosis of many diseases, including cancer. In this study, chiral vanadium trioxide/vanadium nitride (V2O3/VN) nanoparticles (NPs) modified with an organic dye (cyanine 3 [Cy3]) were prepared for ROS sensing. Chiral V2O3/VN NPs were prepared with the "ligand-induced chirality" strategy and showed a g-factor of up to 0.12 at a wavelength of 512 nm. To the best of our knowledge, this g-factor is the highest value of all chiral ceramic nanomaterials. The very high g-factor of the nanoprobe confers very high sensitivity, because the higher g-factor, the higher sensitivity. In the presence of ROS, V3+ in the chiral V2O3/VN nanoprobe undergoes a redox reaction to form V2O5, reducing the circular dichroism and absorbance signals, whereas the fluorescence signal of Cy3 is restored. With this nanoprobe, the limits of detection for the circular dichroic and fluorescence signals in living cells are 0.0045 nmol/106 and 0.018 nmol/106 cells, respectively. This chiral nanoprobe can also monitor ROS levels in vivo by fluorescence. This strategy provides an innovative approach to the detection of ROS and is expected to promote the wider application of chiral nanomaterials for biosensing.

Exploration of individual colorectal cancer cell responses to H2O2 eustress using hopping probe scanning ion conductance microscopy

Colorectal cancer (CRC), a widespread malignancy, is closely associated with tumor microenvironmental hydrogen peroxide (H2O2) levels. Some clinical trials targeting H2O2 for cancer treatment have revealed its paradoxical role as a promoter of cancer progression. Investigating the dynamics of cancer cell H2O2 eustress at the single-cell level is crucial. In this study, non-contact hopping probe mode scanning ion conductance microscopy (HPICM) with high-sensitive Pt-functionalized nanoelectrodes was employed to measure dynamic extracellular to intracellular H2O2 gradients in individual colorectal cancer Caco-2 cells. We explored the relationship between cellular mechanical properties and H2O2 gradients. Exposure to 0.1 or 1 mmol/L H2O2 eustress increased the extracellular to intracellular H2O2 gradient from 0.3 to 1.91 or 3.04, respectively. Notably, cellular F-actin-dependent stiffness increased at 0.1 mmol/L but decreased at 1 mmol/L H2O2 eustress. This H2O2-induced stiffness modulated AKT activation positively and glutathione peroxidase 2 (GPX2) expression negatively. Our findings unveil the failure of some H2O2-targeted therapies due to their ineffectiveness in generating H2O2, which instead acts eustress to promote cancer cell survival. This research also reveals the complex interplay between physical properties and biochemical signaling in cancer cells' antioxidant defense, illuminating the exploitation of H2O2 eustress for survival at the single-cell level. Inhibiting GPX and/or catalase (CAT) enhances the cytotoxic activity of H2O2 eustress against CRC cells, which holds significant promise for developing innovative therapies targeting cancer and other H2O2-related inflammatory diseases.

Electrochemical Nanopipette Sensor for In Vitro/In Vivo Detection of Cu2+ Ions

In vitro/in vivo detection of copper ions is a challenging task but one which is important in the development of new approaches to the diagnosis and treatment of cancer and hereditary diseases such as Alzheimer's, Wilson's, etc. In this paper, we present a nanopipette sensor capable of measuring Cu2+ ions with a linear range from 0.1 to 10 μM in vitro and in vivo. Using the gold-modified nanopipette sensor with a copper chelating ligand, we evaluated the accumulation ability of the liposomal form of an anticancer Cu-containing complex at three levels of biological organization. First, we detected Cu2+ ions in a single cell model of human breast adenocarcinoma MCF-7 and in murine melanoma B16 cells. The insertion of the nanoelectrode did not result in leakage of the cell membrane. We then evaluated the distribution of the Cu-complex in MCF-7 tumor spheroids and found that the diffusion-limited accumulation was a function of the depth, typical for 3D culture. Finally, we demonstrated the use of the sensor for Cu2+ ion detection in the brain of an APP/PS1 transgenic mouse model of Alzheimer's disease and tumor-bearing mice in response to injection (2 mg kg-1) of the liposomal form of the anticancer Cu-containing complex. Enhanced stability and selectivity, as well as distinct copper oxidation peaks, confirmed that the developed sensor is a promising tool for testing various types of biological systems. In summary, this research has demonstrated a minimally invasive electrochemical technique with high temporal resolution that can be used for the study of metabolism of copper or copper-based drugs in vitro and in vivo.

Liposomal form of 2-alkylthioimidazolone-based copper complexes for combined cancer therapy

Aim: To develop an optimized approach for encapsulating a 2-alkylthioimidazolone-based copper coordination compound within liposomes, which could offer treatment of cancer and bacterial infections by reactive oxygen species generation toxicity mechanisms. Materials & methods: For drug-loaded liposome preparation, lipids and drug mixture in organic solvents was injected into copper salt solution, forming a coordination compound simultaneously embedded in the lipid bilayer. In vitro tests were performed on MCF7 and MDA-MB-231 breast cancer cells. Results: Liposomes had a loading capacity of up to 1.75% (molar drug-to-lipid ratio). In vitro tests showed increased viability and accumulation of the liposomal formulation compared with free drug as well as lack of cytotoxicity in hepatocytes. Conclusion: This optimized technique for encapsulating large copper complexes in liposomes could be used to improve their delivery and better treat cancer and bacterial infections.

X-ray and UV Irradiation-Induced Reactive Oxygen Species Mediated Antibacterial Activity in Fe and Pt Nanoparticle-Decorated Si-Doped TiCaCON Films

Bone implants with biocompatibility and the ability to biomineralize and suppress infection are in high demand. The occurrence of early infections after implant placement often leads to repeated surgical treatment due to the ineffectiveness of antibiotic therapy. Therefore, an extremely attractive solution to this problem would be the ability to initiate bacterial protection of the implant by an external influence. Here, we present a proof-of-concept study based on the generation of reactive oxygen species (ROS) by the implant surface in response to X-ray irradiation, including through a layer of 3 mm adipose tissue, providing bactericidal protection. The effect of UV and X-ray irradiation of the implant surface on the ROS formation and the associated bactericidal activity was compared. The focus of our study was light-sensitive Si-doped TiCaCON films decorated with Fe and Pt nanoparticles (NPs) with photoinduced antibacterial activity mediated by ROS. In the visible and infrared range of 300-1600 nm, the films absorb more than 60% of the incident light. The high light absorption capacity of TiO2/TiC and TiO2/TiN heterostructures was demonstrated by density functional theory calculations. After short-term (5-10 s) low-dose X-ray irradiation, the films generated significantly more ROS than after UV illumination for 1 h. The Fe/TiCaCON-Si films showed enhanced biomineralization capacity, superior cytocompatibility, and excellent antibacterial activity against multidrug-resistant hospital Escherichia coli U20 and K261 strains and methicillin-resistant Staphylococcus aureus MW2 strain. Our study clearly demonstrates that oxidized Fe NPs are a promising alternative to the widely used Ag NPs in antibacterial coatings, and X-rays can potentially be used in ROS-regulating therapy to suppress inflammation in case of postimplant complications.

Measuring Melanoma Nanomechanical Properties in Relation to Metastatic Ability and Anti-Cancer Drug Treatment Using Scanning Ion Conductance Microscopy

A cell's mechanical properties have been linked to cancer development, motility and metastasis and are therefore an attractive target as a universal, reliable cancer marker. For example, it has been widely published that cancer cells show a lower Young's modulus than their non-cancerous counterparts. Furthermore, the effect of anti-cancer drugs on cellular mechanics may offer a new insight into secondary mechanisms of action and drug efficiency. Scanning ion conductance microscopy (SICM) offers a nanoscale resolution, non-contact method of nanomechanical data acquisition. In this study, we used SICM to measure the nanomechanical properties of melanoma cell lines from different stages with increasing metastatic ability. Young's modulus changes following treatment with the anti-cancer drugs paclitaxel, cisplatin and dacarbazine were also measured, offering a novel perspective through the use of continuous scan mode SICM. We found that Young's modulus was inversely correlated to metastatic ability in melanoma cell lines from radial growth, vertical growth and metastatic phases. However, Young's modulus was found to be highly variable between cells and cell lines. For example, the highly metastatic cell line A375M was found to have a significantly higher Young's modulus, and this was attributed to a higher level of F-actin. Furthermore, our data following nanomechanical changes after 24 hour anti-cancer drug treatment showed that paclitaxel and cisplatin treatment significantly increased Young's modulus, attributed to an increase in microtubules. Treatment with dacarbazine saw a decrease in Young's modulus with a significantly lower F-actin corrected total cell fluorescence. Our data offer a new perspective on nanomechanical changes following drug treatment, which may be an overlooked effect. This work also highlights variations in cell nanomechanical properties between previous studies, cancer cell lines and cancer types and questions the usefulness of using nanomechanics as a diagnostic or prognostic tool.

Recent advancements in single-cell metabolic analysis for pharmacological research

Cellular heterogeneity is crucial for understanding tissue biology and disease pathophysiology. Pharmacological research is being advanced by single-cell metabolic analysis, which offers a technique to identify variations in RNA, proteins, metabolites, and drug molecules in cells. In this review, the recent advancement of single-cell metabolic analysis techniques and their applications in drug metabolism and drug response are summarized. High-precision and controlled single-cell isolation and manipulation are provided by microfluidics-based methods, such as droplet microfluidics, microchamber, open microfluidic probe, and digital microfluidics. They are used in tandem with variety of detection techniques, including optical imaging, Raman spectroscopy, electrochemical detection, RNA sequencing, and mass spectrometry, to evaluate single-cell metabolic changes in response to drug administration. The advantages and disadvantages of different techniques are discussed along with the challenges and future directions for single-cell analysis. These techniques are employed in pharmaceutical analysis for studying drug response and resistance pathway, therapeutic targets discovery, and in vitro disease model evaluation.

Electrical Characterization and Analysis of Single Cells and Related Applications

Biological parameters extracted from electrical signals from various body parts have been used for many years to analyze the human body and its behavior. In addition, electrical signals from cancer cell lines, normal cells, and viruses, among others, have been widely used for the detection of various diseases. Single-cell parameters such as cell and cytoplasmic conductivity, relaxation frequency, and membrane capacitance are important. There are many techniques available to characterize biomaterials, such as nanotechnology, microstrip cavity resonance measurement, etc. This article reviews single-cell isolation and sorting techniques, such as the micropipette separation method, separation and sorting system (dual electrophoretic array system), DEPArray sorting system (dielectrophoretic array system), cell selector sorting system, and microfluidic and valve devices, and discusses their respective advantages and disadvantages. Furthermore, it summarizes common single-cell electrical manipulations, such as single-cell amperometry (SCA), electrical impedance sensing (EIS), impedance flow cytometry (IFC), cell-based electrical impedance (CEI), microelectromechanical systems (MEMS), and integrated microelectrode array (IMA). The article also enumerates the application and significance of single-cell electrochemical analysis from the perspectives of CTC liquid biopsy, recombinant adenovirus, tumor cells like lung cancer DTCs (LC-DTCs), and single-cell metabolomics analysis. The paper concludes with a discussion of the current limitations faced by single-cell analysis techniques along with future directions and potential application scenarios.

A novel method for synthesis of carbon dots and their applications in reactive oxygen species (ROS) and glucose detections

A simple and novel method is proposed for preparation of water-soluble fluorescent carbon dots (C-dots), which have potential to be applied in detecting reactive oxygen species (ROS). The C-dots with high fluorescence quantum yield were created by hydrothermal methods with lactose as the carbon source and tris(hydroxylmethyl)aminomethane (Tris) as the surface passivation reagent. The C-dots have some unique characteristics such as excellent biocompatibility with a broad pH working range of 5-11 and high fluorescence, which makes them especially useful in the bio-detection field. The optical properties, surface groups, and element components of the prepared C-dots have been systematically studied by fluorescence spectroscopy. This facile approach is efficient and environmentally friendly and allows large-scale production of the C-dots without any further post-treatment. The C-dots have been adopted as probes for fluorescence turn-off detection owing to their high sensitivity to the hydroxyl radical. The detection limit can reach ∼0.1 μM under optimized conditions when using hydrogen peroxide as the source for generating ROS. Moreover, when paired with glucose oxidase, these C-dots can track glucose concentrations in samples. This adaptability suggests their potential in detecting various metabolites, paving the way for practical uses in disease detection.

Osteoconductive, Osteogenic, and Antipathogenic Plasma Electrolytic Oxidation Coatings on Titanium Implants with BMP-2

We report a one-pot plasma electrolytic oxidation (PEO) strategy for forming a multi-element oxide layer on the titanium surface using complex electrolytes containing Na2HPO4, Ca(OH)2, (NH2)2CO, Na2SiO3, CuSO4, and KOH compounds. For even better bone implant ingrowth, PEO coatings were additionally loaded with bone morphogenetic protein-2 (BMP-2). The samples were tested in vivo in a mouse craniotomy model. Tests for bactericidal and fungicidal activity were carried out using clinically isolated multi-drug-resistant Escherichia coli (E. coli) K261, E. coli U20, methicillin-resistant Staphylococcus aureus (S. aureus) CSA154 bacterial strains, and Neurospora crassa (N. crassa) and Candida albicans (C. albicans) D2528/20 fungi. The PEO-Cu coating effectively inactivated both Gram-positive and Gram-negative bacteria at low concentrations of Cu2+ ions: minimal bactericidal concentration for E. coli and N. crassa (99.9999%) and minimal inhibitory concentration (99.0%) for S. aureus were 5 ppm. For all studied bacterial and fungal strains, PEO-Cu coating completely prevented the formation of bacterial and fungal biofilms. PEO and PEO-Cu coatings demonstrated bone remodeling and moderate osteoconductivity in vivo, while BMP-2 significantly enhanced osteoconduction and osteogenesis. The obtained results are encouraging and indicate that Ti-based materials with PEO coatings loaded with BMP-2 can be widely used in customized medicine as implants for orthopedics and cranio-maxillofacial surgery.

Investigation of the Antifungal and Anticancer Effects of the Novel Synthesized Thiazolidinedione by Ion-Conductance Microscopy

In connection with the emergence of new pathogenic strains of Candida, the search for more effective antifungal drugs becomes a challenge. Part of the preclinical trials of such drugs can be carried out using the innovative ion-conductance microscopy (ICM) method, whose unique characteristics make it possible to study the biophysical characteristics of biological objects with high accuracy and low invasiveness. We conducted a study of a novel synthesized thiazolidinedione's antimicrobial (for Candida spp.) and anticancer properties (on samples of the human prostate cell line PC3), and its drug toxicity (on a sample of the human kidney cell line HEK293). We used a scanning ion-conductance microscope (SICM) to obtain the topography and mechanical properties of cells and an amperometric method using Pt-nanoelectrodes to register reactive oxygen species (ROS) expression. All data and results are obtained and presented for the first time.

ROS Production by a Single Neutrophil Cell and Neutrophil Population upon Bacterial Stimulation

The reactive oxygen species (ROS) production by a single neutrophil after stimulation with S. aureus and E. coli was estimated by an electrochemical amperometric method with a high time resolution. This showed significant variability in the response of a single neutrophil to bacterial stimulation, from a "silent cell" to a pronounced response manifested by a series of chronoamperometric spikes. The amount of ROS produced by a single neutrophil under the influence of S. aureus was 5.5-fold greater than that produced under the influence of E. coli. The response of a neutrophil granulocyte population to bacterial stimulation was analyzed using luminol-dependent biochemiluminescence (BCL). The stimulation of neutrophils with S. aureus, as compared to stimulation with E. coli, caused a total response in terms of ROS production that was seven-fold greater in terms of the integral value of the light sum and 13-fold greater in terms of the maximum peak value. The method of ROS detection at the level of a single cell indicated the functional heterogeneity of the neutrophil population, but the specificity of the cellular response to different pathogens was the same at the cellular and population levels.

Distinguishing the Cellular Transport of Folic Acid Conjugated Nano-Drugs among Different Cell Lines by Using Force Tracing Technique

Folic acid (FA) is a ligand that has been renowned for its strong binding to FA receptor (FR), and the robustness of the specific interaction has led to the generation of multitudinous tumor-targeted nano-drug delivery systems. However, selecting the appropriate FA targeted nano-drugs according to types of cancerous cells to achieve a high effect is critical. Understanding of how the drug is transported through the cell membrane and is delivered intracellularly is very important in screening ideal targeted nano-drugs for cancerous changes in different organs. Herein, by using a force tracing technique based on atomic force microscopy (AFM), the dynamic process of FA-polyamidoamine-Doxorubicin (FA-PAMAM-DOX) entry into different tumor cells (HeLa and A549) and normal cells (Vero) was monitored in real time. The cell membrane transport efficacy of FA-PAMAM-DOX in tumor cells with an FR high overexpression level (HeLa) and FR low overexpression level (A549) is analyzed, which is significantly higher than that in normal cells (Vero), especially for HeLa cells. Subsequently, the intracellular delivery efficiency of FA-PAMAM-DOX in different cell lines was measured by using fluorescence imaging and AFM-based nanoindentation techniques. This report will help to discover the cellular transport mechanism of nano-drugs and screen out optimal therapeutic nano-drugs for different types of tumors.

Photoinduced Reduction of Novel Dual-Action Riboplatin Pt(IV) Prodrug

Controlled photoreduction of Pt(IV) prodrugs is a challenging task due to the possibility of targeted light-controlled activation of anticancer agents without affecting healthy tissues. Also, a conjugation of photosensitizers and clinically used platinum drugs into one Pt(IV) prodrug allows combining photodynamic therapy and chemotherapy approaches into one molecule. Herein, we designed the cisplatin-based Pt(IV) prodrug Riboplatin with tetraacetylriboflavin in the axial position. A novel Pt(IV) prodrug is able to act both as a photodynamic therapy (PDT) agent through the conversion of ground-state ³O₂ to excited-state ¹O₂ and as an agent of photoactivated chemotherapy (PACT) through releasing of cisplatin under gentle blue light irradiation, without the requirement of a reducing agent. The light-induced behavior of Riboplatin was investigated using an electrochemical sensor in MCF-7 tumor spheroids. Photocontrolled cisplatin release and ROS generation were detected electrochemically in real time. This appears to be the first confirmation of simultaneous photoactivated release of anticancer drug cisplatin and ROS from a dual-action Pt(IV) prodrug observed from the inside of living tumor spheroids.

Live Imaging in Planarians: Immobilization and Real-Time Visualization of Reactive Oxygen Species

Imaging of living animals allows the study of metabolic processes in relation to cellular structures or larger functional entities. To enable in vivo imaging during long-term time-lapses in planarians, we combined and optimized existing protocols, resulting in an easily reproducible and inexpensive procedure. Immobilization with low-melting-point agarose eliminates the use of anesthetics, avoids interfering with the animal during imaging-functionally or physically-and allows recovering the organisms after the imaging procedure. As an example, we used the immobilization workflow to image the highly dynamic and fast-changing reactive oxygen species (ROS) in living animals. These reactive signaling molecules can only be studied in vivo and mapping their location and dynamics during different physiological conditions is crucial to understand their role in developmental processes and regeneration. In the current protocol, we describe both the immobilization and ROS detection procedure. We used the intensity of the signals together with pharmacological inhibitors to validate the signal specificity and to distinguish it from the autofluorescent nature of the planarian.

Sensing Cells-Peptide Hydrogel Interaction In Situ via Scanning Ion Conductance Microscopy

Peptide-based hydrogels were shown to serve as good matrices for 3D cell culture and to be applied in the field of regenerative medicine. The study of the cell-matrix interaction is important for the understanding of cell attachment, proliferation, and migration, as well as for the improvement of the matrix. Here, we used scanning ion conductance microscopy (SICM) to study the growth of cells on self-assembled peptide-based hydrogels. The hydrogel surface topography, which changes during its formation in an aqueous solution, were studied at nanoscale resolution and compared with fluorescence lifetime imaging microscopy (FLIM). Moreover, SICM demonstrated the ability to map living cells inside the hydrogel. A zwitterionic label-free pH nanoprobe with a sensitivity > 0.01 units was applied for the investigation of pH mapping in the hydrogel to estimate the hydrogel applicability for cell growth. The SICM technique that was applied here to evaluate the cell growth on the peptide-based hydrogel can be used as a tool to study functional living cells.

Synthesis and Preclinical Evaluation of Small-Molecule Prostate-Specific Membrane Antigen-Targeted Abiraterone Conjugate

Prostate cancer is the second most common type of cancer among men. The main method of its treatment is androgen deprivation therapy, which has a wide range of side effects. One of the solutions to this challenge is the targeted delivery of drugs to prostate cancer cells. In this study, we performed the synthesis of a novel small-molecule PSMA-targeted conjugate based on abiraterone. Cytotoxicity, the induction of intracellular reactive oxygen species, and P450-cytochrome species inhibition were investigated for this conjugate PSMA-abiraterone. The conjugate demonstrated a preferential effect on prostate tumor cells, remaining inactive at up to 100 µM in human fibroblast cells. In addition, it revealed preferential efficacy, specifically on PSMA-expressing lines with a 65% tumor growth inhibition level on 22Rv1 (PSMA+) xenografts after 14-fold oral administration of PSMA-Abi at a single dose of 500 mg/kg (7.0 g/kg total dose) was observed. This compound showed significantly reduced acute toxicity with comparable efficacy compared to AbiAc.

Intravital electrochemical nanosensor as a tool for the measurement of reactive oxygen/nitrogen species in liver diseases

Reactive oxygen/nitrogen species (ROS/RNS) are formed during normal cellular metabolism and contribute to its regulation, while many pathological processes are associated with ROS/RNS imbalances. Modern methods for measuring ROS/RNS are mainly based on the use of inducible fluorescent dyes and protein-based sensors, which have several disadvantages for in vivo use. Intravital electrochemical nanosensors can be used to quantify ROS/RNS with high sensitivity without exogenous tracers and allow dynamic ROS/RNS measurements in vivo. Here, we developed a method for quantifying total ROS/RNS levels in the liver and evaluated our setup in live mice using three common models of liver disease associated with ROS activation: acute liver injury with CCl4, partial hepatectomy (HE), and induced hepatocellular carcinoma (HCC). We have demonstrated using intravital electrochemical detection that any exposure to the peritoneum in vivo leads to an increase in total ROS/RNS levels, from a slight increase to an explosion, depending on the procedure. Analysis of the total ROS/RNS level in a partial hepatectomy model revealed oxidative stress, both in mice 24 h after HE and in sham-operated mice. We quantified dose-dependent ROS/RNS production in CCl4-induced injury with underlying neutrophil infiltration and cell death. We expect that in vivo electrochemical measurements of reactive oxygen/nitrogen species in the liver may become a routine approach that provides valuable data in research and preclinical studies.

Protein Misfolding and Aggregation in the Brain: Common Pathogenetic Pathways in Neurodegenerative and Mental Disorders

Mental disorders represent common brain diseases characterized by substantial impairments of social and cognitive functions. The neurobiological causes and mechanisms of psychopathologies still have not been definitively determined. Various forms of brain proteinopathies, which include a disruption of protein conformations and the formation of protein aggregates in brain tissues, may be a possible cause behind the development of psychiatric disorders. Proteinopathies are known to be the main cause of neurodegeneration, but much less attention is given to the role of protein impairments in psychiatric disorders' pathogenesis, such as depression and schizophrenia. For this reason, the aim of this review was to discuss the potential contribution of protein illnesses in the development of psychopathologies. The first part of the review describes the possible mechanisms of disruption to protein folding and aggregation in the cell: endoplasmic reticulum stress, dysfunction of chaperone proteins, altered mitochondrial function, and impaired autophagy processes. The second part of the review addresses the known proteins whose aggregation in brain tissue has been observed in psychiatric disorders (amyloid, tau protein, α-synuclein, DISC-1, disbindin-1, CRMP1, SNAP25, TRIOBP, NPAS3, GluA1, FABP, and ankyrin-G).

Nano- and Microsensors for In Vivo Real-Time Electrochemical Analysis: Present and Future Perspectives

Electrochemical nano- and microsensors have been a useful tool for measuring different analytes because of their small size, sensitivity, and favorable electrochemical properties. Using such sensors, it is possible to study physiological mechanisms at the cellular, tissue, and organ levels and determine the state of health and diseases. In this review, we highlight recent advances in the application of electrochemical sensors for measuring neurotransmitters, oxygen, ascorbate, drugs, pH values, and other analytes in vivo. The evolution of electrochemical sensors is discussed, with a particular focus on the development of significant fabrication schemes. Finally, we highlight the extensive applications of electrochemical sensors in medicine and biological science.

Electrochemical Detection of a Novel Pt(IV) Prodrug with the Metronidazole Axial Ligand in the Hypoxic Area

We report herein a Pt(IV) prodrug with metronidazole in axial positions Pt-Mnz. The nitroaromatic axial ligand was conjugated with a cisplatin scaffold to irreversibly reduce under hypoxic conditions, thereby retaining the Pt(IV) prodrug in the area of hypoxia. X-ray near-edge adsorption spectroscopy (XANES) on dried drug-preincubated tumor cell samples revealed a gradual release of cisplatin from the Pt-Mnz prodrug instead of rapid intracellular degradation. The ability of the prodrug to penetrate into three-dimensional (3D) spheroid cellular cultures was evaluated by a novel electrochemical assay via a platinum-coated carbon nanoelectrode, capable of single-cell measurements. Using a unique technique of electrochemical measurements in single tumor spheroids, we were able to both detect the real-time response of the axial ligand to hypoxia and establish the depth of penetration of the drug into the tumor model.

Pt(IV) Prodrugs with Non-Steroidal Anti-inflammatory Drugs in the Axial Position

We report herein the design, synthesis, and biological investigation of a series of novel Pt(IV) prodrugs with non-steroidal anti-inflammatory drugs naproxen, diclofenac, and flurbiprofen, as well as these with stearic acid in the axial position. Six Pt(IV) prodrugs 5-10 were designed, which showed superior antiproliferative activity compared to cisplatin as well as an ability to overcome tumor cell line resistance to cisplatin. By tuning the drug lipophilicity via variation of the axial ligands, the most potent Pt(IV) prodrug 7 was obtained, with an enhanced cellular accumulation of up to 153-fold that of cisplatin and nanomolar cytotoxicity both in 2D and 3D cell cultures. Pt²⁺ species were detected at different depths of MCF-7 spheroids after incubation with Pt(IV) prodrugs using a Pt-coated carbon nanoelectrode. Cisplatin accumulation in vivo in the murine mammary EMT6 tumor tissue of BALB/c mice after Pt(IV) prodrug injection was proved electrochemically as well. The drug tolerance study on BALB/c mice showed good tolerance of 7 in doses up to 8 mg/kg.

Echem methods and electrode types of the current in vivo electrochemical sensing

For a long time, people have been eager to realize continuous real-time online monitoring of biological compounds. Fortunately, in vivo electrochemical biosensor technology has greatly promoted the development of biological compound detection. This article summarizes the existing in vivo electrochemical detection technologies into two categories: microdialysis (MD) and microelectrode (ME). Then we summarized and discussed the electrode surface time, pollution resistance, linearity and the number of instances of simultaneous detection and analysis, the composition and characteristics of the sensor, and finally, we also predicted and prospected the development of electrochemical technology and sensors in vivo.

In Vitro/In Vivo Electrochemical Detection of Pt(II) Species

The biodistribution of chemotherapy compounds within tumor tissue is one of the main challenges in the development of antineoplastic drugs, and techniques for simple, inexpensive, sensitive, and selective detection of various analytes in tumors are of great importance. In this paper we propose the use of platinized carbon nanoelectrodes (PtNEs) for the electrochemical detection of platinum-based drugs in various biological models, including single cells and tumor spheroids in vitro and inside solid tumors in vivo. We have demonstrated the quantitative direct detection of Pt(II) in breast adenocarcinoma MCF-7 cells treated with cisplatin and a cisplatin-based DNP prodrug. To realize the potential of this technique in advanced tumor models, we measured Pt(II) in 3D tumor spheroids in vitro and in tumor-bearing mice in vivo. The concentration gradient of Pt(II) species correlated with the distance from the sample surface in MCF-7 tumor spheroids. We then performed the detection of Pt(II) species in tumor-bearing mice treated intravenously with cisplatin and DNP. We found that there was deeper penetration of DNP in comparison to cisplatin. This research demonstrates a minimally invasive, real-time electrochemical technique for the study of platinum-based drugs.

Oxygen-Ozone Therapy for Reducing Pro-Inflammatory Cytokines Serum Levels in Musculoskeletal and Temporomandibular Disorders: A Comprehensive Review

To date, the application of oxygen-ozone (O₂O₃) therapy has significantly increased in the common clinical practice in several pathological conditions. However, beyond the favorable clinical effects, the biochemical effects of O₂O₃ are still far from being understood. This comprehensive review aimed at investigating the state of the art about the effects of O₂O₃ therapy on pro-inflammatory cytokines serum levels as a modulator of oxidative stress in patients with musculoskeletal and temporomandibular disorders (TMD). The efficacy of O₂O₃ therapy could be related to the moderate oxidative stress modulation produced by the interaction of ozone with biological components. More in detail, O₂O₃ therapy is widely used as an adjuvant therapeutic option in several pathological conditions characterized by chronic inflammatory processes and immune overactivation. In this context, most musculoskeletal and temporomandibular disorders (TMD) share these two pathophysiological processes. Despite the paucity of in vivo studies, this comprehensive review suggests that O₂O₃ therapy might reduce serum levels of interleukin 6 in patients with TMD, low back pain, knee osteoarthritis and rheumatic diseases with a concrete and measurable interaction with the inflammatory pathway. However, to date, further studies are needed to clarify the effects of this promising therapy on inflammatory mediators and their clinical implications.

Microalgae-Derived Health Supplements to Therapeutic Shifts: Redox-Based Study Opportunities with AIE-Based Technologies

Reactive oxygen species (ROS) are highly reactive molecules, serve the normal signaling in different cell types. Targeting ROS as the chemical signals, different stress based strategies have been developed to synthesis different anti-inflammatory molecules in microalgae. These molecules could be utilized as health supplements in human. To provoke the ROS-mediated defence systems, their connotation with the associated conditions must be well understood, therefore, proper tools for studying ROS in natural state are essential. The in vivo detection of ROS with phosphorescent probes offers promising opportunities to study these molecules in a non-invasive manner. Most of the common problems in the traditional fluorescent probes are lower photostability, excitation intensity, slow responsiveness, and the microenvironment that challenge their performance. Some ROS-specific aggregationinduced emission luminogens (AIEgens) with pronounced spatial and temporal resolution have recently demonstrated high selectivity, rapid responsiveness, and efficacies to resolve the aggregation-caused quenching issues. The nanocomposites of some AIE-photosensitizers can also improve the ROS-mediated photodynamic therapy. These AIEgens could be used to induce bioactive components in microalgae through altering the ROS signaling, therefore are more auspicious for biomedical research. This study reviews the prospects of AIEgen-based technologies to understand the ROS mediated bio-physiological processes in microalgae for better healthcare benefits.

A ROS-responsive fluorescent probe detecting experimental colitis by functional polymeric nanoparticles

Current evidence shows that oxidative stress plays an essential role in the pathogenesis and progression of inflammatory bowel disease (IBD). TotalROX (λabs/λem = 425/525 nm) is a ratiometric probe with high detection sensitivity and a superior capacity to monitor total cellular oxidative capacity. Herein, we investigated the potential of combining totalROX with an oral nanoparticle delivery system to detect the degree of colitis. This detection system also featured pH-responsive Eudragit S100, hyaluronic acid with high affinity to the CD44 receptor, and chitosan, and demonstrated improved loading efficiency and stability. An experimental mouse model of experimental colitis was induced by dextran sodium sulfate do that we could investigate the ability of our nanoparticles to target the colon and determine the degree of inflammation. We also determined and validated the positive correlation between the fluorescence intensity of the detection product (Ox670, λabs/λem = 650/675 nm) and myeloperoxidase activity (R² = 0.97) and the histopathological score (R² = 0.98). TotalROX had significant ability to measure reactive oxygen species (ROS) produced by cells under inflammatory conditions, as confirmed by in vitro experiments with Caco-2 cells. Collectively, the data generated demonstrate that when loaded with totalROX, these functional nanoparticles are promising tools for cellular imaging after oral administration. This is the first description of a ROS-responsive fluorescent probe to evaluate the degree of colitis in experimental animal models and provides a promising approach for the diagnosis of inflammation in IBD with fluorescence-guided colonoscopy.

Preparation and antitumor application of N-phenylcarbazole/triphenylamine-modified fluorescent half-sandwich iridium(III) Schiff base complexes

Four N-phenylcarbazole/triphenylamine-appended half-sandwich iridium(III) salicylaldehyde Schiff base complexes ([(η⁵-Cp^x)Ir(O^N)Cl]) were prepared and characterized. The complexes exhibited similar antitumor activity to cisplatin and effectively inhibited the migration of tumor cells. Furthermore, the complexes showed favourable hydrolytic activity, while remaining relatively stable in the plasma environment, which facilitated the binding of serum proteins and transport through them. These complexes could decrease the mitochondrial membrane potential, catalyze the oxidation of nicotinamide adenine dinucleotide, induce an increase in intracellular reactive oxygen species (ROS), and eventually result in apoptosis. Aided by their suitable fluorescence property, laser confocal detection showed that the complexes followed an energy-dependent mechanism for their cellular uptake, effectively accumulating in the lysosome and leading to lysosomal damage. In summary, the half-sandwich iridium(III) salicylaldehyde Schiff base complexes could induce lysosomal damage, increase intracellular ROS, and lead to apoptosis, which contributed to their antitumor mechanism of oxidation.

Superoxide Dismutase 1 Nanoparticles (Nano-SOD1) as a Potential Drug for the Treatment of Inflammatory Eye Diseases

Inflammatory eye diseases remain the most common clinical problem in ophthalmology. The secondary processes associated with inflammation, such as overproduction of reactive oxygen species (ROS) and exhaustion of the endogenous antioxidant system, frequently lead to tissue degeneration, vision blurring, and even blindness. Antioxidant enzymes, such as copper-zinc superoxide dismutase (SOD1), could serve as potent scavengers of ROS. However, their delivery into the eye compartments represents a major challenge due to the limited ocular penetration. This work presents a new therapeutic modality specifically formulated for the eye on the basis of multilayer polyion complex nanoparticles of SOD1 (Nano-SOD1), which is characterized by appropriate storage stability and pronounced therapeutic effect without side reactions such as eye irritation; acute, chronic, and reproductive toxicity; allergenicity; immunogenicity; mutagenicity even at high doses. The ability of Nano-SOD1 to reduce inflammatory processes in the eye was examined in vivo in rabbits with a model immunogenic uveitis-the inflammation of the inner vascular tract of the eye. It was shown during preclinical studies that topical instillations of Nano-SOD1 were much more effective compared to the free enzyme in decreasing uveitis manifestations. In particular, we noted statistically significant differences in such inflammatory signs in the eye as corneal and conjunctival edema, iris hyperemia, and fibrin clots. Moreover, Nano-SOD1 penetrates into interior eye structures more effectively than SOD itself and retains enzyme activity in the eye for a much longer period of time, decreasing inflammation and restoring antioxidant activity in the eye. Thus, the presented Nano-SOD1 can be considered as a potentially useful therapeutic agent for the treatment of ocular inflammatory disorders.

Detection of Vascular Reactive Oxygen Species in Experimental Atherosclerosis by High-Resolution Near-Infrared Fluorescence Imaging Using VCAM-1-Targeted Liposomes Entrapping a Fluorogenic Redox-Sensitive Probe

Excessive production of reactive oxygen species (ROS) and the ensuing oxidative stress are instrumental in all phases of atherosclerosis. Despite the major achievements in understanding the regulatory pathways and molecular sources of ROS in the vasculature, the specific detection and quantification of ROS in experimental models of disease remain a challenge. We aimed to develop a reliable and straightforward imaging procedure to interrogate the ROS overproduction in the vasculature and in various organs/tissues in atherosclerosis. To this purpose, the cell-impermeant ROS Brite™ 700 (RB700) probe that produces bright near-infrared fluorescence upon ROS oxidation was encapsulated into VCAM-1-targeted, sterically stabilized liposomes (VLp). Cultured human endothelial cells (EC) and macrophages (Mac) were used for in vitro experiments. C57BL6/J and ApoE-/- mice were randomized to receive normal or high-fat, cholesterol-rich diet for 10 or 32 weeks. The mice received a retroorbital injection with fluorescent tagged VLp incorporating RB700 (VLp-RB700). After two hours, the specific signals of the oxidized RB700 and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl) (NBD-DSPE), inserted into liposome bilayers, were measured ex vivo in the mouse aorta and various organs by high-resolution fluorescent imaging. VLp-RB700 was efficiently taken up by cultured human EC and Mac, as confirmed by fluorescence microscopy and spectrofluorimetry. After systemic administration in atherosclerotic ApoE-/- mice, VLp-RB700 were efficiently concentrated at the sites of aortic lesions, as indicated by the augmented NBD fluorescence. Significant increases in oxidized RB700 signal were detected in the aorta and in the liver and kidney of atherosclerotic ApoE-/- mice. RB700 encapsulation into sterically stabilized VCAM-1-sensitive Lp could be a novel strategy for the qualitative and quantitative detection of ROS in the vasculature and various organs and tissues in animal models of disease. The accurate and precise detection of ROS in experimental models of disease could ease the translation of the results to human pathologies.

Melnikov M, Zyk NV, Skvortsov DA, Lopatukhina EV, Vaneev AN, Gorelkin PV, Erofeev AS, Majouga AG, Beloglazkina EK. New Fe–Cu bimetallic coordination compounds based on ω-ferrocene carboxylic acids and 2-thioimidazol-4-ones: structural, mechanistic and biological studies

Synthesis, characterization and in vitro cytotoxic investigation of a series of new ferrocene-containing derivatives based on ω-ferrocene carboxylic acids and 2-alkylthioimidazolin-4-ones and their copper complexes have been reported.

Therapeutic Potential of Reactive Oxygen Species: State of the Art and Recent Advances

In the last decade, several studies have proven that when at low concentration reactive oxygen species (ROS) show an adaptive beneficial effect and posited the idea that they can be utilized as inexpensive and convenient inducers of tissue regeneration. On the other hand, the recent discovery that cancer cells are more sensitive to oxidative damage paved the way for their use in the selective killing of tumor cells, and sensors to monitor ROS production during cancer treatment are under extensive investigation. Nevertheless, although ROS-activated signaling pathways are well established, less is known about the mechanisms underlying the switch from an anabolic to a cytotoxic response. Furthermore, a high variability in biological response is observed between different modalities of administration, cell types, donor ages, eventual concomitant diseases, and external microenvironment. On the other hand, available preclinical studies are scarce, whereas the quest for the most suitable systems for in vivo delivery is still elusive. Furthermore, new strategies to control the temporal pattern of ROS release need to be developed, if considering their tumorigenic potential. This review initially discusses ROS mechanisms of action and their potential application in stem cell biology, tissue engineering, and cancer therapy. It then outlines the state of art of ROS-based drugs and identifies challenges faced in translating ROS research into clinical practice.

Nanoelectrochemical quantification of single-cell metabolism

At the most fundamental level, the behavior of tissue is governed by the activity of its single cells. A detailed examination of single-cell biology is necessary in order to gain a deeper understanding of disease progression. While single-cell genomics and transcriptomics are mature due to robust amplification strategies, the metabolome is difficult to quantify. Nanoelectrochemical techniques stand poised to quantify single-cell metabolism as a result of the fabrication of nanoelectrodes, which allow one to make intracellular electrochemical measurements. This article is concerned with intracellular nanoelectrochemistry, focusing on the sensitive and selective quantification of various metabolites within a single, living cell. We will review the strong literature behind this field, discuss the potential deleterious effects of passing charge inside cells, and provide future outlooks for this promising avenue of inquiry. We also present a mathematical relationship based on Faraday's Law and bulk electrolysis theory to examine the consumption of analyte within a cell due to passing charge at the nanotip.Graphical abstract.