Application of a Cu–chitosan/multiwalled carbon nanotube film-modified electrode for the sensitive determination of rutin

Chitosan, derivatives, and its nanoparticles: Preparation, physicochemical properties, biological activities, and biomedical applications - A comprehensive review

Chitosan, derived from the deacetylation of chitin, is the second most widely used natural polymer, valued for its nontoxic, biocompatible, and biodegradable properties. These attributes have driven extensive research into diverse applications of chitosan and various derivatives. The key characteristics of chitosan muco-adhesion, permeability enhancement, drug release modulation, and antimicrobial activity are primarily due to its amino and hydroxyl groups. However, the limited solubility of raw chitosan in water and most organic solvents has posed challenges for broader application. Numerous chemically modified derivatives have been developed to address these inadequacies with improved physical and chemical properties. Among these derivatives, chitosan nanoparticles have emerged as versatile drug carriers with precise release kinetics and the capacity for targeted delivery, greatly enhancing drug efficacy and safety profiles for therapeutic applications. Due to these unique physicochemical properties, chitosan and chitosan nanoparticles are promising for improved drug delivery, vaccine administration, transplantation, gene therapy, and diagnostics. This review examines the physicochemical properties and bioactivities of chitosan and chitosan nanoparticles, emphasizing their broad-ranging biomedical applications.

Air plasma assisted directional electrodeposition of Ag nanoparticles on carbon cloth for electrochemical detection of rutin

The air plasma-induced defects and O-related groups are employed as anchoring sites for the directional electrochemical deposition of Ag nanoparticles (AgNPs) with even distribution and a narrow size range on carbon cloth (CC). The strategy of integrating the air plasma and AgNPs provides plentiful adsorption and catalytic sites, a large electroactive area, superhydrophilic interface, and a smooth charge and mass-transfer pathway. As a consequence, the fabricated self-supporting electrode of AgNPs@CC - P displays an excellent sensing performance toward rutin with a large linear concentration window (0.05 ~ 30 µM), a small LOD (4.2 nM, S/N = 3) and LOQ (32 nM, S/N = 10), as well as good stability and reproducibility. The fabricated sensor is successfully applied to the practical detection of rutin in tablets and beverages with good accuracy. The self-supporting sensor also shows potential for fabricating flexible and soft sensing devices for real-time monitoring.

Fabrication of Highly Fluorescent Nitrogen and Phosphorus Dual-Doped Carbon Dots for Selective Sensing of Rutin

Based on nitrogen and phosphorus co-doped carbon dots (NP-CDs), a direct, quick, and selective sensing probe for fluorometric detection of rutin has been developed. Utilizing ethylene diamine tetra acetic acid (EDTA) as a carbon and nitrogen source and diammonium hydrogen phosphate (NH4)2HPO4 as a nitrogen and phosphorus source. The NP-CDs were synthesized in less than 3 min with a straightforward one-step microwave pyrolysis process with a high quantum yield (63.8%). After being excited at λ = 360 nm, the produced NP-CDs displayed a maximum bluish fluorescence at λem of 420 nm. Rutin quenched the fluorescence of the produced NP-CDs based on the inner filter effect and static quenching processes. Along with the International Council of Harmonization (ICH) requirements, the developed spectrofluorometric method was validated. The linearity range was 0.50-35.00 μg/mL of rutin. The developed NP-CDs were successfully employed to determine rutin concentrations in marketed tablets. The developed method is quick, simple, consistent, sensitive, and selective, and it does not require expensive chemicals or specialized instruments. This study paves the path for future application of NP-CD in pharmaceutical analysis.

A catalytic amplification platform based on Fe2O3 nanoparticles decorated graphene nanocomposites for highly sensitive detection of rutin

Exploration of nanocomposites with exceptional catalytic activities is essential for harnessing the unique advantages of each constituent in the domains of pharmaceutical analysis and electrochemical sensing. In this regard, we illustrated the synthesis of iron oxide/N-doped reduced graphene oxide (Fe2O3/N-rGO) nanocomposites through a one-step thermal treatment of iron phthalocyanine (FePc), melamine, and graphene oxide for electrochemical sensing. The large specific surface area and good conductivity of N-rGO can efficiently capture rutin molecules and accelerate electron transport, thereby improving the electrochemical performance. Moreover, the Fe2O3 nanoparticles with distinct electronic characteristics significantly enhanced the detection sensitivity of the constructed electrochemical platform. Because of the outstanding electrical conductivity, an extensive surface area, and synergistic catalysis, Fe2O3/N-rGO was employed as an advanced electrode modifier to build an electrochemical sensing platform for rutin detection. Significantly, the manufactured sensor showed a broad detection range from 7 nM to 150 μM and a high sensitivity of 5632 μA mM-1. Furthermore, the fabricated sensor showed desirable results in terms of stability, selectivity, and practical application. This work presents a facile method to prepare Fe2O3/N-rGO and supplies a valuable example for building metal oxide/graphene nanocomposites for electrochemical analysis.

Assessment of cell wall degrading enzymes by molecular docking and dynamics simulations: Effects of novel infrared treatment

Cell wall-degrading enzymes' activities under infrared treatment are vital for peeling; it is critical to elucidate the mechanisms of the novel infrared peeling in relation to its impact on cell wall-degrading enzymes. In this study, the activities, and gene expressions of eight degrading enzymes closely related to pectin, cellulose and hemicellulose were determined. The most influential enzyme was selected from them, and then the mechanism of its changes was revealed by molecular dynamics simulation and molecular docking. The results demonstrated that infrared had the most significant effect on β-glucosidase among the tested enzymes (increased activity and up-regulated gene expression of 195.65 % and 7.08, respectively). It is suggested infrared crucially promotes cell wall degradation by affecting β-glucosidase. After infrared treatment, β-glucosidase's structure moderately transformed to a more open one and became flexible, increasing the affinity between β-glucosidase and substrate (increasing 75 % H-bonds and shortening 15.89 % average length), thereby improving β-glucosidase's activity. It contributed to cell wall degradation. The conclusion is that the effect of infrared on the activity, gene expression and molecular structure of β-glucosidase causes damage to the peel, thus broadening the applicability of the new infrared dry-peeling technique, which has the potential to replace traditional wet-peeling methods.

An electrochemical sensor based on CS-MWCNT and AuNPs for the detection of mycophenolic acid in plasma

For patients receiving organ transplants, monitoring the blood concentration of MPA can provide timely information on whether MPA has reached the effective therapeutic window to better function while reducing the incidence of rejection or adverse reactions. In this study, an electrochemical sensor for the detection of MPA was built using a nanocomposite made of CS-MWCNT and AuNPs. At the same time, the high performance liquid phase (HPLC) method for MPA was established and compared with this sensor. The surface morphology, structure, and roughness of the material on the electrode were characterized by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and atomic force microscopy (AFM). In addition, the electrochemical behavior of the modified electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The standard curve was obtained in blank plasma, not pure buffer solution. The peak current was linearly related to the MPA concentration in the linear range of 0.001-0.1 mM with a detection limit of 0.05 μM and good anti-interference ability. Moreover, the sensor was employed with success for the determination of MPA in rat plasma with good recovery. The electrochemical sensor presented here is eco-friendly, and sensitive, and offers a great possibility for practical applicability.

An electrochemical sensor based on Ce-MOF-derived Ce-doped poly(3,4-ethylenedioxythiophene) composite for efficient determination of rutin in food

As a common antioxidant and nutritional fortifier in food chemistry, rutin has positive therapeutic effects against novel coronaviruses. Here, Ce-doped poly(3,4-ethylenedioxythiophene) (Ce-PEDOT) nanocomposites derived through cerium-based metal-organic framework (Ce-MOF) as a sacrificial template have been synthesized and successfully applied to electrochemical sensors. Due to the outstanding electrical conductivity of PEDOT and the high catalytic activity of Ce, the nanocomposites were used for the detection of rutin. The Ce-PEDOT/GCE sensor detects rutin over a linear range of 0.02-9 μM with the limit of detection of 14.7 nM (S/N = 3). Satisfactory results were obtained in the determination of rutin in natural food samples (buckwheat tea and orange). Moreover, the redox mechanism and electrochemical reaction sites of rutin were investigated by the CV curves of scan rate and density functional theory. This work is the first to demonstrate the combined PEDOT and Ce-MOF-derived materials as an electrochemical sensor to detect rutin, thus opening a new window for the application of the material in detection.

Copper-Guanosine Nanorods (Cu-Guo NRs) as a Laccase Mimicking Nanozyme for Colorimetric Detection of Rutin

Inspired by laccase activity, herein, Cu-guanosine nanorods (Cu-Guo NRs) have been synthesized for the first time through a simple procedure. The activity of the Cu-Guo NR as the laccase mimicking nanozyme has been examined in the colorimetric sensing of rutin (Rtn) by a novel and simple spectrophotometric method. The distinct changes in the absorbance signal intensity of Rtn and a distinguished red shift under the optimum condition based on pH and ionic strength values confirmed the formation of the oxidized form of Rtn (o-quinone) via laccase-like nanozyme activity of Cu-Guo NRs. A vivid and concentration-dependent color variation from green to dark yellow led to the visual detection of Rtn in a broad concentration range from 770 nM to 54.46 µM with a limit of detection (LOD) of 114 nM. The proposed methodology was successfully applied for the fast tracing of Rtn in the presence of certain common interfering species and various complex samples such as propolis dry extract, human biofluids, and dietary supplement tablets, with satisfactory precision. The sensitivity and selectivity of the developed sensor, which are bonuses in addition to rapid, on-site, cost-effective, and naked-eye determination of Rtn, hold great promise to provide technical support for routine analysis in the real world.

Efficient Detection of 2,6-Dinitrophenol with Silver Nanoparticle-Decorated Chitosan/SrSnO3 Nanocomposites by Differential Pulse Voltammetry

Herein, an ultra-sonication technique followed by a photoreduction technique was implemented to prepare silver nanoparticle-decorated Chitosan/SrSnO₃ nanocomposites (Ag-decorated Chitosan/SrSnO₃ NCs), and they were successively used as electron-sensing substrates coated on a glassy carbon electrode (GCE) for the development of a 2,6-dinitrophenol (2,6-DNP) efficient electrochemical sensor. The synthesized NCs were characterized in terms of morphology, surface composition, and optical properties using FESEM, TEM, HRTEM, BET, XRD, XPS, FTIR, and UV-vis analysis. Ag-decorated Chitosan/SrSnO₃ NC/GCE fabricated with the conducting binder (PEDOT:PSS) was found to analyze 2,6-DNP in a wide detection range (LDR) of 1.5~13.5 µM by applying the differential pulse voltammetry (DPV) approach. The 2,6-DNP sensor parameters, such as sensitivity (54.032 µA µM^-1 cm^-2), limit of detection (LOD; 0.18 ± 0.01 µM), limit of quantification (LOQ; 0.545 µM) reproducibility, and response time, were found excellent and good results. Additionally, various environmental samples were analyzed and obtained reliable analytical results. Thus, it is the simplest way to develop a sensor probe with newly developed nanocomposite materials for analyzing the carcinogenic contaminants from the environmental effluents by electrochemical approach for the safety of environmental and healthcare fields in a broad scale.

Synthesis and characterization of cinnamic acid conjugated N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride derivatives: A hybrid flocculant with antibacterial activity

The modified natural biopolymers, recognized as environmentally friendly flocculants, are gaining tremendous attention in the field of water treatment. In this study, a novel hybrid flocculant with antibacterial activity, cinnamic acid (CA) conjugated N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (HTCC) derivative (HTCC-CA), was prepared via quaternary ammonium and amide reactions. The characterization, flocculation, and antibacterial activities were carried out to access the structural properties and potential application. The results of UV-vis, FT-TR, and ¹H NMR confirmed the successful synthesis of HTCC-CA1-3 derivatives. XRD and TGA revealed the lower crystallinity and thermal stability of HTCC-CA1-3 derivatives than chitosan (CS). Bacterial flocculation and antibacterial tests indicated the excellent flocculation effect of HTCC-CA1-3 derivatives and showed high antibacterial activity for Escherichia coli suspension. Moreover, the mechanism of action of the derivatives was investigated via zeta potential measurements and scanning electron microscope, which can be summed up as the effective interaction between charges. The results proved that HTCC-CA derivatives are promising agents for wastewater treatment.

Highly sensitive simultaneous electrochemical determination of myricetin and rutin via solid phase extraction on a ternary Pt@r-GO@MWCNTs nanocomposite

The simultaneous electrochemical determination of myricetin and rutin remains a challenge due to their indistinguishable potentials. To solve this problem, we constructed a ternary platinum nanoparticle, reduced graphene oxide, multi-walled carbon nanotubes (Pt@r-GO@MWCNTs) nanocomposite via a facile one-pot synthetic method. Under the optimized conditions, the ternary Pt@r-GO@MWCNTs nanocomposite exhibited good electrocatalytic activity toward myricetin and rutin via solid phase extraction and excellent performance for the simultaneous determination of myricetin and rutin. The oxidation peak current of myricetin was proportional to its concentrations in the range of 0.05–50 μM with a detection limit of 0.01 μM (S/N = 3). The linear range for rutin was 0.05–50 μM with a detection limit of 0.005 μM (S/N = 3). The ternary nanocomposite sensor also exhibited good reproducibility and stability, and was successfully used for the simultaneous determination of myricetin and rutin in real orange juice samples with recoveries ranging between 100.57% and 108.46%.

Facile Electrochemical Sensor for Nanomolar Rutin Detection Based on Magnetite Nanoparticles and Reduced Graphene Oxide Decorated Electrode

A new electrochemical sensor for nanomolar rutin detection based on amine-functionalized Fe₃O₄ nanoparticles and electrochemically reduced graphene oxide nanocomposite modified glassy carbon electrode (NH₂-Fe₃O₄ NPs-ErGO/GCE) was fabricated through a simple method, and the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and electrochemical technique were used to characterize the modified electrode. The electrochemical behavior of rutin on the Fe₃O₄ NPs-ErGO/GCE was studied in detail. The electrochemical response of rutin at this modified electrode was remarkably higher than that of the bare GCE or other modified GCE (GO/GCE, Fe₃O₄ NPs-GO/GCE, and ErGO/GCE). Under the optimum determination conditions, Fe₃O₄ NPs-ErGO/GCE provided rutin with a broader detection range of 6.0 nM–0.1 µM; 0.1–8.0 µM and 8.0–80 µM, a minimum detectable concentration of 4.0 nM was obtained after 210 s accumulation. This novel method was applied in determination of rutin in pharmaceutical tablets and urine samples with satisfactory results.

Electrocomposite Developed with Chitosan and Ionic Liquids Using Screen-Printed Carbon Electrodes Useful to Detect Rutin in Tropical Fruits

This work reports the development of a composite of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BP₄) and chitosan (CS) described in previous reports through a new method using cyclic voltammetry with 10 cycles at a scan rate of 50.0 mV s⁻¹. This method is different from usual methods such as casting, deposition, and constant potential, and it allows the development of an electroactive surface toward the oxidation of rutin by stripping voltammetry applied to the detection in tropical fruits such as orange, lemon, and agraz (Vaccinium meridionale Swartz), with results similar to those reported in previous studies. In addition, the surface was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and Raman spectroscopy. The limit of detection was 0.07 µmol L⁻¹ and the relative standard deviation (RSD) of 10 measurements using the same modified electrode was 0.86%. Moreover, the stability of the sensor was studied for six days using the same modified electrode, where the variation of the signal using a known concentration of rutin (RT) was found to be less than 5.0%. The method was validated using a urine chemistry control spiked with known amounts of RT and possible interference was studied using ten substances including organic and biological compounds, metal ions, and dyes. The results obtained in this study demonstrated that this electrodeveloped composite was sensitive, selective, and stable.

Sensitive determination of rutin by spectrofluorimetry using carbon dots synthesized from a non-essential amino acid

The present study describes the synthesis of carbon dots (CDs) using a non-essential amino acid, asparagine as a precursor. The HR-TEM image shows that the size of the prepared CDs was 2.9±0.2nm with a spherical morphology. The UV-visible spectrum of CDs exhibits a major band at 307nm along with a shoulder band around 207nm corresponding to n-π* and π-π* transitions, respectively. Further, the CDs show emission maximum at 441nm when excited at 348nm. The synthesized CDs were then exploited for the determination of rutin by spectrofluorimetry based on the decrease in emission intensity at 441nm. It was found that emission intensity of CDs at 441nm was decreased while adding 0.5μM rutin to CDs. On the other hand, addition of other metal ions and anions including 5mM Mg²⁺, K⁺, Ca²⁺, Na⁺, NO₃^- and oxalate, 2.5mM Cu²⁺ and Fe³⁺ and 3mM glycine, glucose, histidine, proline and cysteine does not affect the emission intensity at 441nm. A good linearity was observed for the emission intensity against 0.5-15μM rutin with a correlation coefficient of 0.997 and the limit of detection was found to be 1×10^-7M (61μg/L) (S/N=3). The real sample analysis was done by determining rutin in a pharmaceutical sample.

Facile construction of reduced graphene oxide–carbon dot complex embedded molecularly imprinted polymers for dual-amplification and selective electrochemical sensing of rutoside

This article reported reduced graphene oxide–carbon dot embedded molecularly imprinted polymers for sensitive and selective electrochemical sensing of rutoside.

One-pot electrochemical preparation of copper species immobilized poly(o-aminophenol)/MWCNT composite with excellent electrocatalytic activity for use as an H2O2 sensor

Redox activity of copper species immobilized poly(o-aminophenol)/multi-walled carbon nanotube for direct electrocatalysis towards detection of H₂O₂.

Rutin detection using highly electrochemical sensing amplified by an Au–Ag nanoring decorated N-doped graphene nanosheet

The novel Au–Ag nanorings/NG modified electrode was found to have a wide linear range from 0.05 μM to 241.2 μM (S/N = 3) with a low detection limit of 0.01 μM when it was employed for rutin detection.