Nafion/lead nitroprusside nanoparticles modified carbon ceramic electrode as a novel amperometric sensor for L-cysteine

Facile synthesis of copper nitroprusside chitosan nanocomposite and its catalytic reduction of environmentally hazardous azodyes

One of the biggest issues affecting the entire world currently is water contamination caused by textile industries' incapacity to properly dispose their wastewater. The presence of toxic textile dyes in the aquatic environment has attracted significant research interest due to their high environmental stability and their negative effects on human health and ecosystems. Therefore, it is crucial to convert the hazardous dyes such as methyl orange (MO) azo dye into environmentally safe products. In this context, we describe the use of Copper Nitroprusside Chitosan (Cu/SNP/Cts) nanocomposite as a nanocatalyst for the chemical reduction of azodyes by sodium borohydride (NaBH4). The Cu/SNP/Cts was readily obtained by chemical coprecipitation in a stoichiometric manner. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy were applied to investigate chemical, phase, composition, and molecular interactions. Additionally, Scanning electron microscope (SEM) was used to examine the nanomaterial's microstructure. UV-vis spectroscopy was utilized for studying the Cu Nitroprusside Chitosan's catalytic activity for the reduction of azodye. The Cu/SNP/Cts nanocomposite demonstrated outstanding performance with total reduction time 160 s and pseudo-first order constant of 0.0188 s-1. Additionally, the stability and reusability study demonstrated exceptional reusability up to 5 cycles with minimal activity loss. The developed Cu/SNP/Cts nanocomposite act as efficient nanocatalysts for the reduction of harmful Methyl orange azodye.

Copper nitroprusside: An innovative approach for targeted cancer therapy via ROS modulation

The clinical application of nanomaterials for chemodynamic therapy (CDT), which generate multiple reactive oxygen species (ROS), presents significant challenges. These challenges arise due to insufficient levels of endogenous hydrogen peroxide and catalytic ions necessary to initiate Fenton reactions. As a result, sophisticated additional delivery systems are required. In this study, a novel bimetallic copper (II) pentacyanonitrosylferrate (Cu(II)NP, Cu[Fe(CN) 5 NO]) material was developed to address these limitations. This material functions as a multiple ROS generator at tumoral sites by self-inducing hydrogen peroxide and producing peroxynitrite (ONOO-) species. The research findings demonstrate that this material exhibits low toxicity towards normal liver organoids, yet shows potent antitumoral effects on High Grade Serous Ovarian Cancer (HGSOC) organoid patients, regardless of platinum resistance. Significantly, this research introduces a promising therapeutic opportunity by proposing a single system capable of replacing the need for H2O2, additional catalysts, and NO-based delivery systems. This innovative system exhibits remarkable multiple therapeutic mechanisms, paving the way for potential advancements in clinical treatments.

Methods of Protection of Electrochemical Sensors against Biofouling in Cell Culture Applications

In this work, we evaluated more than 10 antifouling layers presenting different modes of action for application in electrochemical sensors. These layers included porous materials, permselective membranes, hydrogels, silicate sol-gels, proteins, and sp3 hybridized carbon. To evaluate the protective effects of the antifouling modification as well as its impact on the catalyst, we adsorbed a redox mediator on the electrode surface. Five of the tested coatings allowed us to preserve the electrochemical properties of the tested mediator. Later studies showed that sol-gel silicate layer, poly-l-lactic acid, and poly(l-lysine)-g-poly(ethylene glycol) were the only ones capable of sustaining the catalyst's performance during prolonged incubation in a cell culture medium. The highest signal deterioration was observed, as expected during the first few hours of incubation in a cell culture environment. Tested layers exhibited different dynamics of the protective effect. The poly-l-lactic acid layer presented lower changes in the first hours of the study but suffered complete signal deterioration after 72 h. Whereas the signal intensity of the silicate layer was lowered by half after just 3 h but was still visible after 6 weeks of constant incubation of the electrode in the cell culture.

Nitric oxide releasing novel amino acid-derived polymeric nanotherapeutic with anti-inflammatory properties for rapid wound tissue regeneration

Endogenous gasotransmitter nitric oxide (NO) is a central signalling molecule that modulates wound healing by maintaining homeostasis, collagen formation, wound contraction, anti-microbial action and accelerating tissue regeneration. The optimum delivery of NO using nanoparticles (NPs) is clinically challenging; hence, it is drawing significant attention in wound healing. Herein, a novel polymeric nanoplatform loaded with sodium nitroprusside (SP) NPs was prepared and used for wound healing to obtain the sustained release of NO in therapeutic quantities. SP NPs-induced excellent proliferation (∼300%) of mouse fibroblast (L929) cells was observed. With an increase in the SP NPs dose at 200 μg mL-1 concentration, a 200% upsurge in proliferation was observed along with enhanced migration, and only 17.09 h were required to fill the 50% gap compared to 37.85 h required by the control group. Further, SP NPs showed an insignificant impact on the coagulation cascade, revealing safe wound-healing treatment when tested in isolated rat RBCs. Additionally, SP NPs exhibited excellent angiogenic activity at a 10 μg mL-1 dose. Moreover, the formulated SP nanoformulation is non-irritant, non-toxic, and does not produce any skin sensitivity reaction on the rat's skin. Further, an in vivo wound healing study revealed that within 11 days of treatment with SP nanoformulation, 99.2 ± 1.0% of the wound was closed, while in the control group, only 45.5 ± 3.8% was repaired. These results indicate that owing to sustained NO release, the SP NP and SP nanoformulations are paramount with enormous clinical potential for the regeneration of wound tissues.

Iron nitroprusside as a chemodynamic agent and inducer of ferroptosis for ovarian cancer therapy

ChemoDynamic Therapy (CDT) is a powerful therapeutic modality using Fenton/Fenton-like reactions to produce oxidative stress for cancer treatment. However, the insufficient amount of catalyst ions and ROS scavenging activity of glutathione peroxidase (GPX4) limit the application of this approach. Therefore, a tailored strategy to regulate the Fenton reaction more efficiently (utilizing dual metal cations) and inhibit the GPX4 activity, is in great demand. Herein, a CDT system is based on dual (Fe²⁺ metals) iron pentacyanonitrosylferrate or iron nitroprusside (FeNP) having efficient ability to catalyze the reaction of endogenous H₂O₂ to form highly toxic ˙OH species in cells. Additionally, FeNP is involved in ferroptosis via GPX4 inhibition. In particular, FeNP was structurally characterized, and it is noted that a minimum dose of FeNP is required to kill cancer cells while a comparable dose shows negligible toxicity on normal cells. Detailed in vitro studies confirmed that FeNP participates in sustaining apoptosis, as determined using the annexin V marker. Cellular uptake results showed that in a short time period, FeNP enters lysosomes and, due to the acidic lysosomal pH, releases Fe²⁺ ions, which are involved in ROS generation (˙OH species). Western blot analyses confirmed the suppression of GPX4 activity over time. Importantly, FeNP has a therapeutic effect on ovarian cancer organoids derived from High-Grade Serous Ovarian Cancer (HGSOC). Furthermore, FeNP showed biocompatible nature towards normal mouse liver organoids and in vivo. This work presents the effective therapeutic application of FeNP as an efficient Fenton agent along with ferroptosis inducer activity to improve CDT, through disturbing redox homeostasis.

Use of metal nanoparticles for preconcentration and analysis of biological thiols

Metal nanoparticles (NPs) exhibit several unique physicochemical properties, including redox activity, surface plasmon resonance, ability to quench fluorescence, biocompatibility, or a high surface-to-volume ratio. They are being increasingly used in analysis and preconcentration of thiol containing compounds, because they are able to spontaneously form a stable Au/Ag/Cu-S dative bond. They thus find wide application in environmental and particularly in medical science, especially in the analysis of biological thiols, the endogenous compounds that play a significant role in many biological systems. In this review article, we provide an overview of various types of NPs that have been applied in analysis and preconcentration of biological thiols, mainly in human biological fluids. We first discuss shortly the types of NPs and their synthesis, properties, and their ability to interact with thiol compounds. Then we outline the sample preconcentration and analysis methods that were used for this purpose with special emphasis on optical, electrochemical, and separation techniques.

Low-Cost and Efficient Nickel Nitroprusside/Graphene Nanohybrid Electrocatalysts as Counter Electrodes for Dye-Sensitized Solar Cells

Novel nickel nitroprusside (NNP) nanoparticles with incorporated graphene nanoplatelets (NNP/GnP) were used for the first time as a low-cost and effective counter electrode (CE) for dye-sensitized solar cells (DSSCs). NNP was synthesized at a low-temperature (25 °C) solution process with suitable purity and crystallinity with a size range from 5 to 10 nm, as confirmed by different spectroscopic and microscopic analyses. The incorporation of an optimized amount of GnP (0.2 wt%) into the NNP significantly improved the electrocatalytic behavior for the redox reaction of iodide (I-)/tri-iodide (I3-) by decreasing the charge-transfer resistance at the CE/electrolyte interface, lower than the NNP- and GnP-CEs, and comparable to the Pt-CE. The NNP/GnP nanohybrid CE when applied in DSSC exhibited a PCE of 6.13% (under one sun illumination conditions) with the Jsc, Voc, and FF of 14.22 mA/cm2, 0.628 V, and 68.68%, respectively, while the PCE of the reference Pt-CE-based DSSC was 6.37% (Jsc = 14.47 mA/cm2, Voc = 0.635 V, and FF = 69.20%). The low cost of the NNP/GnP hybrid CE with comparable photovoltaic performance to Pt-CE can be potentially exploited as a suitable replacement of Pt-CE in DSSCs.

Voltammetric Determination of Cysteine (2-amino-3-mercaptopropanoic acid, CySH) by Means of 4,4'-biphenol as a Homogeneous Mediator

In the present research, 4,4′-biphenol was used as a homogeneous mediator for determining cysteine (CySH) on a Glassy Carbon Electrode (GCE). To describe the electrochemical properties of 4,4′-biphenol and to examine its electrocatalytic impacts on cysteine oxidation, both Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV) were employed. Our findings revealed that 4,4′-biphenol could significantly accelerate the reactions related to electron transfer to CySH. Moreover, the diffusion coefficient of CySH and its reaction with the catalytic constant of 4,4′-diphenoquinone was estimated via chronoamperometry technique. The results showed that cysteine concentration range of 10-1000 μM led to linear increases in the oxidation peaks, thus to providing a detection of 0.99 μM with R² = 0.993. A Relative Standard Deviation (RSD) of 2.5% was achieved after performing 7 cysteine replicates (100 μM), and CySH was successfully determined in real serum samples through the proposed approach.

A glassy carbon electrode modified with hollow cubic cuprous oxide for voltammetric sensing of L-cysteine

This paper reports on an electrochemical sensing system for L-cysteine. It is based on the use of hollow cubic Cu₂O particles that were prepared in two steps. First, the Cu₂O/ polystyrene (PS) composites were prepared by a surface ion exchange strategy for in-situ reductive deposition on the surface of carboxy-capped PS particles. Thereafter, the PS particles were removed from the Cu₂O/PS composites by treatment with tetrahydrofuran (THF). The resulting hollow cubic Cu₂O particles were placed in a Nafion matrix on a glassy carbon electrode (GCE) which exhibits high surface area, good site accessibility and excellent electrocatalytic activity for L-cysteine. The cyclic voltammetric response of the modified GCE to L-cysteine is about 2.8-fold stronger than when using a GCE modified with pure Cu₂O. The detection limit for L-cysteine is lower by about 1 order of magnitude, and the working voltage is rather low (-0.08 V vs. Ag/AgCl). An excellent electrochemical selectivity for L-cysteine over other amino acids was also achieved. The method was successfully applied to the determination of L-cysteine in pharmaceutical samples. Graphical abstract An electrochemical sensing system for the detection of L-cysteine in amino acid injections has been established by using the hollow cubic Cu₂O particles as recognition element.

Voltammetric Study of the Copper Pentacyanonitrosylferrate Adsorbed on the Silica Modified with a Poly(propylene)imine Hexadecylamine Dendrimer for Determination of Nitrite

Poly(propylene)imine hexadecylamine dendrimer (DAB-Am-16) was anchored on the surface of 3-chloropropylsilyl silica gel and subsequently interacted with copper nitroprusside. The composite was characterized by infrared (FTIR), energy dispersive X-ray (EDX), and cyclic voltammetry. The above techniques confirmed the successful anchoring of the dendrimer on the silica gel modified surface and its interaction with copper nitroprusside. The cyclic voltammogram of CuNPSD was found to exhibit two redox couples with (Eθ′)1= 0.30 V and (Eθ′)2= 0.78 V versus Ag/AgCl ( mol L−1;  mV s−1) attributed to the redox processes and , respectively. The CuNPSD-modified graphite paste electrode was found to show a linear response of to  mol L−1for nitrite determination with a detection limit (DL) of  mol L−1and an amperometric sensitivity of 25.0 mA/mol L−1. The CuNPSD-modified graphite paste electrode was found to show a good electrochemical stability and an excellent response to the electrocatalytic oxidation of sodium nitrite.

Natural and artificial ion channels for biosensing platforms

The single-molecule selectivity and specificity of the binding process together with the expected intrinsic gain factor obtained when utilizing flow through a channel have attracted the attention of analytical chemists for two decades. Sensitive and selective ion channel biosensors for high-throughput screening are having an increasing impact on modern medical care, drug screening, environmental monitoring, food safety, and biowarefare control. Even virus antigens can be detected by ion channel biosensors. The study of ion channels and other transmembrane proteins is expected to lead to the development of new medications and therapies for a wide range of illnesses. From the first attempts to use membrane proteins as the receptive part of a sensor, ion channels have been engineered as chemical sensors. Several other types of peptidic or nonpeptidic channels have been investigated. Various gating mechanisms have been implemented in their pores. Three technical problems had to be solved to achieve practical biosensors based on ion channels: the fabrication of stable lipid bilayer membranes, the incorporation of a receptor into such a structure, and the marriage of the modified membrane to a transducer. The current status of these three areas of research, together with typical applications of ion-channel biosensors, are discussed in this review.

Fabrication and characterization of molybdenum(VI)complex-TiO2 nanoparticles modified electrode for the electrocatalytic determination of L-cysteine

A novel voltammetric sensor for the determination of L-cysteine (L-Cys) was fabricated based on a TiO2 nanoparticles/bis [bis(salicylidene-1,4-phenylenediamine)-molybdenum(VI)] carbon paste electrode. The electrochemical behavior of the sensor was investigated in detail by cyclic voltammetry. The apparent electron transfer rate constant (ks) and charge transfer coefficient (?) of the TiO2 nanoparticles / molybdenum(VI) complex/CPE were also determined by cyclic voltammetry and found to be about 4.53 s?1 and 0.54, respectively. The sensor displayed good electrocatalytic activity towards the oxidation of LCys. The peak potential for the oxidation of L-Cys was lowered by at least 130 mV compared with that obtained at an unmodified CPE. Under optimal conditions, the linear range spans L-Cys concentrations from 1.5?10?6 M to 1.2?10?3 M and the detection limit was 0.70 ? 0.01 ?M at a signal-to-noise ratio of 2. In addition, the sensor showed good stability and reproducibility.