Electrochemical sensor based on a chitosan-molybdenum vanadate nanocomposite for detection of hydroxychloroquine in biological samples

Thermoplastic PHB-Reinforced Chitosan Piezoelectric Films for Biodegradable Pressure Sensors

Flexible and wearable pressure sensors have attracted significant attention in the fields of smart medicine and human health monitoring. Nevertheless, the design and fabrication of degradable disposable pressure sensors still face urgent challenges. Herein, we fabricated poly(3-hydroxybutyrate) (PHB)-reinforced chitosan (CS) piezoelectric films for intelligent sensors through a simple, low-cost, and environmentally friendly roll-forming method. The results show that PHB doping successfully increased the effective piezoelectric coefficient of the chitosan-based film from 40.12 to 49.38 pm/V (a 23% increase). Simultaneously, the pressure sensor based on the CS/PHB film exhibited excellent response sensitivity (484 mV/kPa) and a wide linear response range (0-130 kPa), which could be used as haptic sensors and motion monitoring sensors for the fast response to human motion signals. Additionally, the CS/PHB film could be completely degraded within 18 days in a natural soil environment, demonstrating outstanding degradability. Therefore, chitosan-based piezoelectric films with excellent biodegradability and piezoelectric characteristics have been successfully fabricated in this work, which will promote the innovative development of green chitosan-based electronic devices and disposable pressure sensors.

Molecularly imprinted polymer composite membranes: From synthesis to diverse applications

This review underscores the fundamentals of MIP-CMs and systematically summarizes their synthetic strategies and applications, and potential developments. MIP-CMs are widely acclaimed for their versatility, finding applications in separation, filtration, detection, and trace analysis, as well as serving as scaffolds in a range of analytical, biomedical and industrial contexts. Also characterized by extraordinary selectivity, remarkable sensitivity, and outstanding capability to bind molecules, those membranes are also cost-effective, highly stable, and configurable in terms of recognition and, therefore, inalienable in various application fields. Issues relating to the potential future for the paper are discussed in the last section with the focus on the improvement of resource practical application across different areas. Hence, this review can be seen as a kind of cookbook for the design and fabrication of MIP-CMs with an intention to expand the scope of their application.

Carbon Nanomaterials-Based Novel Hybrid Platforms for Electrochemical Sensor Applications in Drug Analysis

Nowadays, the rapid improvements in the medical and pharmaceutical fields increase the diversity and use of drugs. However, problems such as the use of multiple or combined drugs in the treatment of diseases and insensible use of over-the-counter drugs have caused concerns about the side-effect profiles and therapeutic ranges of drugs and environmental contamination and pollution problems due to pharmaceuticals waste. Therefore, the analysis of drugs in various media such as biological, pharmaceutical, and environmental samples is an important topic of discussion. Electrochemical methods are advantageous for sensor applications due to their easy application, low cost, versatility, high sensitivity, and environmentally-friendliness. Carbon nanomaterials such as diamond-like carbon thin films, carbon nanotubes, carbon nanofibers, graphene oxide, and nanodiamonds are used to enhance the performance of the electrochemical sensors with catalytic effects. To further improve this effect, it is aimed to create hybrid platforms by using different carbon nanomaterials together or with materials such as conductive polymers and ionic liquids. In this review, the most used carbon nanoforms will be evaluated in terms of electrochemical characterizations and physicochemical properties. Furthermore, the effect of hybrid platforms developed in the most recent studies on electrochemical sensors will be examined and evaluated in terms of drug analysis studies in the last five years.

Tailored Covalent Organic Framework Platform: From Multistimuli, Targeted Dual Drug Delivery by Architecturally Engineering to Enhance Photothermal Tumor Therapy

Engineering bulk covalent organic frameworks (COFs) to access specific morphological structures holds paramount significance in boosting their functions in cancer treatment; nevertheless, scant effort has been dedicated to exploring this realm. Herein, silica core-shell templates and multifunctional COF-based reticulated hollow nanospheres (HCOFs) are novelly designed as a versatile nanoplatform to investigate the simultaneous effect of dual-drug chemotherapy and photothermal ablation. Taking advantage of the distinct structural properties of the template, the resulting two-dimensional (2D) HCOF, featuring large internal voids and a peripheral interconnected mesoporous shell, presents intriguing benefits over its bulk counterparts for cancer treatment, including a well-defined morphology, an outstanding drug loading capability (99.6%) attributed to its ultrahigh surface area (2087 m2/g), great crystallinity, improved tumor accumulation, and an adjustable drug release profile. After being loaded with hydrophilic doxorubicin with a remarkable loading capacity, the obtained drug-loaded HCOFs were coated with gold nanoparticles (Au NPs) to confer them with three properties, including pore entrance blockage, active-targeting capability, and improved biocompatibility via secondary modification, besides high near infrared (NIR) absorption for efficient photothermal hyperthermia cancer suppression. The resultant structure was functionalized with mono-6-thio-β-cyclodextrin (β-CD) as a second pocket to load docetaxel as the hydrophobic anticancer agent (combination index = 0.33). The dual-drug-loaded HCOF displayed both pH- and near-infrared-responsive on-demand drug release. In vitro and in vivo evaluations unveiled the prominent synergistic performance of coloaded HCOF in cancer elimination upon NIR light irradiation. This work opens up a new avenue for exciting applications of structurally engineered HCOFs as hydrophobic/hydrophilic drug carriers as well as multimodal treatment agents.

Temperature-Induced Conversion of 2D Vanadium-Doped MoSe2 Nanosheets to 1D V2MoO8 Rods: Enhanced Performance in Electrochemical Antibiotic Detection in Biological and Environmental Samples

In this work, new strategies were developed to prepare 1D-V2MoO8 (VMO) rods from 2D V-doped MoSe2 nanosheets (VMoSe2) with good control over morphology and crystallinity by a facile hydrothermal and calcination process. The morphological changes from 2D to 1D rods were controlled by changing the calcination temperature from 300 to 600 °C. The elimination of Se and the incorporation of O into the V-Mo structure were evaluated by TGA, p-XRD, Raman, FE-SEM, EDAX, FE-TEM, and XPS analyses. These results prove that the optimization of the physical parameters leads to changes in the crystal phase and textural properties of the prepared material. The VMoSe2 and its calcined products were investigated as electrochemical sensors for the detection of the antibacterial drug nitrofurantoin (NFT). At a calcination temperature of 500 °C, the modified screen-printed carbon electrodes (SPCE) proved to be an excellent electrochemical sensor for the detection of NFT in neutral media. Under the optimized conditions, VMO-500 °C/SPCE exhibits low detection limit (LOD) (0.015 μM), wide linear ranges (0.1-31, 47-1802 μM), good sensitivity, and selectivity. The proposed sensor was successfully used for the analysis of NFT in real samples with good recovery results. Moreover, the reduction potential of NFT agreed well with the theoretical analysis using quantum chemical calculations, with the B3LYP with 6-31G(d,p) basis set predicting an E0 value of -0.45 V. The interaction between the electrode surface and NFT via the LUMO diagram and the electrostatic potential surface is also discussed.

Multilayered Fe3O4@(ZIF-8)3 combined with a computer-vision-enhanced immunosensor for chloramphenicol enrichment and detection

The misuse and overuse of chloramphenicol poses severe threats to food safety and human health. In this work, we developed a magnetic solid-phase extraction (MSPE) pretreatment material coated with a multilayered metal-organic framework (MOF), Fe3O4 @ (ZIF-8)3, for the separation and enrichment of chloramphenicol from fish. Furthermore, we designed an artificial-intelligence-enhanced single microsphere immunosensor. The inherent ultra-high porosity of the MOF and the multilayer assembly strategy allowed for efficient chloramphenicol enrichment (4.51 mg/g within 20 min). Notably, Fe3O4 @ (ZIF-8)3 exhibits a 39.20% increase in adsorption capacity compared to Fe3O4 @ZIF-8. Leveraging the remarkable decoding abilities of artificial intelligence, we achieved the highly sensitive detection of chloramphenicol using a straightforward procedure without the need for specialized equipment, obtaining a notably low detection limit of 46.42 pM. Furthermore, the assay was successfully employed to detect chloramphenicol in fish samples with high accuracy. The developed immunosensor offers a robust point-of-care testing tool for safeguarding food safety and public health.

Highly sensitive detection of multiple antiviral drugs using graphitized hydroxylated multi-walled carbon nanotubes/ionic liquids-based electrochemical sensors

Global outbreaks and the spread of viral diseases in the recent years have led to a rapid increase in the usage of antiviral drugs (ATVs), the residues and metabolites of which are discharged into the natural environment, posing a serious threat to human health. There is an urgent need to develop sensitive and rapid detection tools for multiple ATVs. In this study, we developed a highly sensitive electrochemical sensor comprising a glassy carbon electrode (GCE) modified with graphitized hydroxylated multi-walled carbon nanotubes (G-MWCNT-OH) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6, IL) for the detection of six ATVs including famciclovir (FCV), remdesivir (REM), favipiravir (FAV), hydroxychloroquine sulfate (HCQ), cepharanthine (CEP) and molnupiravir (MOL). The morphology and structure of the G-MWCNT-OH/IL nanocomposites were characterized comprehensively, and the electroactive surface area and electron conductivity of G-MWCNT-OH/IL/GCE were determined using cyclic voltammetry and electrochemical impedance spectroscopy. The thermodynamic stability and non-covalent interactions between the G-MWCNT-OH and IL were evaluated through quantum chemical simulation calculations, and the mechanism of ATV detection using the G-MWCNT-OH/IL/GCE was thoroughly examined. The detection conditions were optimized to improve the sensitivity and stability of electrochemical sensors. Under the optimal experimental conditions, the G-MWCNT-OH/IL/GCE exhibited excellent electrocatalytic performance and detected the ATVs over a wide concentration range (0.01-120 μM). The limit of detections (LODs) were 42.3 nM, 55.4 nM, 21.9 nM, 15.6 nM, 10.6 nM, and 3.2 nM for FCV, REM, FAV, HCQ, CEP, and MOL, respectively. G-MWCNT-OH/IL/GCE was also highly stable and selective to the ATVs in the presence of multiple interfering analytes. This sensor exhibited great potential for enabling the quantitative detection of multiple ATVs in actual water environment.

Green Synthesis and Characterization of Biologically Synthesized and Antibiotic-Conjugated Silver Nanoparticles followed by Post-Synthesis Assessment for Antibacterial and Antioxidant Applications

The paper presents the antibacterial and antioxidant activities of silver nanoparticles (AgNPs) when conjugated with two antibiotics levofloxacin and ciprofloxacin as well as biologically synthesized nanoparticles from Moringa oleifera and Curcuma longa. Leaves of Moringa and powder of Curcuma were used in the green synthesis of silver nanoparticles. Ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used for the characterization of the synthesized silver nanoparticles. Comparison of levofloxacin and ciprofloxacin and their conjugated AgNPs was also studied for antibacterial and antioxidant activity. The synthesis of Moringa-AgNPs, turmeric-AgNPs, levofloxacin-AgNPs, and ciprofloxacin-AgNPs was confirmed by UV spectroscopy. An absorption peak value of 400-450 nm was observed, and light to dark brown color indicated the synthesis of AgNPs. Moringa-AgNPs revealed high antioxidant activity (80.3 ± 3.14) among all of the synthesized AgNPs. Lev-AgNPs displayed the highest zone of inhibition for Staphylococcus aureus, while in Escherichia coli, Cip-AgNPs showed high antibacterial activity. Furthermore, AgNPs synthesized using green methods exhibit high and efficient antimicrobial activities against two food-borne pathogens. Biologically synthesized nanoparticles exhibited antibacterial activity against E. coli (13.73 ± 0.46 with Tur-AgNPs and 13.53 ± 0.32 with Mor-AgNPs) and S. aureus (14.16 ± 0.24 with Tur-AgNPs and 13.36 ± 0.77 with Mor-AgNPs) by using a well diffusion method with significant shrinkage and damage of the bacterial cell wall, whereas antibiotic-conjugated nanoparticles showed high antibacterial activity compared to biologically synthesized nanoparticles with 14.4 ± 0.37 for Cip-AgNPs and 13.93 ± 0.2 for Lev-AgNPs for E. coli and 13.3 ± 0.43 for Cip-AgNPs and 14.33 ± 0.12 for Lev-AgNPs for S. aureus. The enhanced efficiency of conjugated silver nanoparticles is attributed to their increased surface area compared to larger particles. Conjugation of different functional groups contributes to improved reactivity, creating active sites for catalytic reactions. Additionally, the precise control over the size and shape of green-synthesized nanoparticles further augments their catalytic and antibiotic activities.

Fluorometric and colorimetric platforms for rapid and sensitive hydroxychloroquine detection in aqueous samples

The detection of pharmaceuticals has been an active area of research with numerous application areas ranging from therapeutic and environmental monitoring to pharmaceutical manufacturing and diagnostics. And, the emergence of COVID-19 pandemic has increased the demand for detection of certain active pharmaceutical ingredients such as Hydroxychloroquine (HCQ) mainly due to their increased manufacturing and usage. In this study, we present two optical, fluorometric and colorimetric, detection platforms for the rapid and sensitive detection of HCQ. These platforms take advantage of the interactions between the highly fluorescent dye Thioflavin T (ThT) and Tel24 G-quadruplex (G4) DNA structure, as well as the salt-induced aggregation behavior of negatively charged citrate-capped silver nanoparticles (Cit-AgNPs) in the presence of HCQ. In the fluorometric method, the addition of HCQ led to a significant and rapid decrease in the fluorescence signal of the ThT + Tel24 probe. In the colorimetric method, HCQ induced the aggregation of Cit-AgNPs in the presence of NaCl, resulting in a noticeable color change from yellowish-gray to colorless. Under the optimized conditions, the colorimetric platform exhibited a linear range of 18.0-240.0 nM and a detection limit of 9.2 nM, while the fluorometric platform showed a linear range of 0.24-5.17 μM and a detection limit of 120 nM. The selectivity of the proposed optical methods towards the target analyte was demonstrated by evaluating the response to other structurally similar small molecules. Finally, the practical applicability of both detection systems was confirmed by analyzing HCQ-spiked human urine samples that yielded average recoveries ranging from 75.4 to 110.2 % for the fluorometric platform and 86.9-98.2 % for the colorimetric platform. These results indicate the potential of the developed methods for HCQ detection in complex matrices.

Oxygen vacancy-rich Fe2(MoO4)3 combined with MWCNTs for electrochemical sensors of fentanyl and its analogs

Hundreds of thousands of people dying from the abuse of fentanyl and its analogs. Hence, the development of an efficient and highly accurate detection method is extremely relevant and challenging. Therefore, we proposed the introduction of oxygen defects into Fe2(MoO4)3 nanoparticles for improving the catalyst performance and combining it with multi-walled carbon nanotubes (MWCNTs) for electrochemical detection of fentanyl and its analogs. Oxygen vacancy-rich Fe2(MoO4)3 (called r-Fe2(MoO4)3) nanoparticles were successfully synthesized and characterized in detail by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman spectra, BET, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) and investigated by comparison with oxygen vacancy-poor Fe2(MoO4)3 (called p-Fe2(MoO4)3). The obtained oxygen vacancy-rich Fe2(MoO4)3 was ultrasonically composited with MWCNTs for modification of glassy carbon electrodes (GCEs) used for the electrochemical detection of fentanyl and its analogs. The modified MWCNT-GCE showed ultrasensitivity to fentanyl, sufentanil, alfentanil, and acetylfentanyl with limits of detection (LOD) of 0.006 µmol·L-1, 0.008 µmol·L-1, 0.018 µmol·L-1, and 0.024 µmol·L-1, respectively, and could distinguish among the four drugs based on their peak voltages. Besides, the obtained r-Fe2(MoO4)3/MWCNT composite also exhibited high repeatability, selectivity, and stability. It showed satisfactory detection performance on real samples, with recoveries of 70.53 ~ 94.85% and 50.98 ~ 82.54% in serum and urine for the four drugs in a concentration range 0.2 ~ 1 µM, respectively. The experimental results confirm that the introduction of oxygen vacancies effectively improves the sensitivity of fentanyl electrochemical detection, and this work provides some inspiration for the development of catalytic materials for electrochemical sensors with higher sensitivity.

Efficient and eco-friendly cadmium ion recycling: Ultrasonic enhancement of aluminum powder replacement for low-temperature industrial applications

Replacing cadmium ions in cadmium-containing solutions with aluminum powder is beneficial for cadmium resource recycling and environmental protection. However, the conventional aluminum powder replacement method requires harsh temperatures and prolonged conditions. In this study, the effect and mechanism of ultrasound on the replacement of cadmium with aluminum powder were investigated at low temperatures. Ultrasound has been proven to promote the etching of alumina films through the use of TEM and XPS, providing mechanistic support for the superiority of the new process. A degree of Cd replacement as high as 95.08 % is achieved at a low temperature (60 ℃) and in a short time (20 min) when using ultrasonicated aluminum powder replacement, which is 42.17 % higher than that of conventional aluminum powder. Compared with conventional aluminum powder replacement conditions with the same effect, the introduction of ultrasound can reduce the temperature by 30℃ and shorten the replacement time by 2/3, which has significant advantages in reaction efficiency and safety. The strengthening mechanism of ultrasound on the replacement effect of aluminum powder at low temperatures is revealed through detailed discussions on the corrosion of alumina films, agglomeration of aluminum powder, and adhesion of replacement products to the surface of aluminum powder, dissolved oxygen in the solution, and redissolution of cadmium. Therefore, a new approach for replacing aluminum powder in solutions with high Cd2+ concentrations at low temperatures is proposed in this work, which is expected to solve the existing harsh and dangerous problems of industrial aluminum powder replacement.

A review on nanotechnological perspective of "the amyloid cascade hypothesis" for neurodegenerative diseases

Neurodegenerative diseases (NDs) are characterized by progressive degeneration of neurons which deteriorates the brain functions. An early detection of the onset of NDs is utmost important, as it will provide the fast treatment strategies to prevent further progression of the disease. Conventionally, accurate diagnosis of the brain related disorders is difficult in their early phase. To solve this problem, nanotechnology based neurofunctional imaging and biomarker detection techniques have been developed which allows high specificity and sensitivity towards screening and diagnosis of NDs. Another challenge to treat the brain related disorders is to overcome the complex integrity of blood-brain-barrier (BBB) for the delivery of theranostic agents. Fortunately, utilization of nanomaterials has been pursued as promising strategy to address this challenge. Herein, we critically highlighted the recent improvements in the field of neurodiagnostic and therapeutic approaches involving innovative strategies for diagnosis, and inhibition of protein aggregates. We have provided particular emphasis on the use of nanotechnology which can push forward the blooming research growth in this field to win the battle against devastating NDs.

Synthesis and its characterisation of selenium/silver/chitosan and cellular toxicity against liver carcinoma cells studies

Liver cancer is one of the most common lethal malignancy in the world. To treat liver cancer, new cure options are crucial. The use of natural substances along nanosciences may provide healing with lower toxicity and a smaller amount of side properties. In this research, The three-component selenium-silver-chitosan nanocomposite (Se-Ag-CS NCs) were synthesised with the help of ultrasound in a stepwise manner. The as-synthesised Se-Ag-CS NCs were characterised accordingly by applying powder X-Ray diffraction (PXRD), Fourier transforms infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive x-ray analysis (EDX), transmission electron microscopy (TEM), dynamic light scattering (DLS) and potential. The PXRD demonstrated that the NCs were synthesised successfully and the grain sizes of 27.3 were obtained. The FESEM and TEM analyses have shown the NCs have a nano-sized structure with spherical and rod-like morphologies in a coating of CS. The DLS analysis also revealed that NCs were synthesised in nanoscale particles. The NCs' surface charge was also positive due to the presence of chitosan. Different concentrations of NCs (0, 0.125, 0.250, 0.500, and 1 mg/ml) were tested at different times (24, 48, and 72 h) to measure cytotoxicity against liver cancer cells. The results showed at a concentration of 1 mg/mL in 72 h, the most toxicity effects were applied to liver cancer cells. Moreover, the results indicated NCs can inhibit the growth of cancer cells in a dose-dependent manner, while the toxicity of nanocomposite on normal cells was less. It is important to create nanocomposites derived from natural polymers as a new strategy in cancer treatment that can fight cancer cells while having low toxicity for normal cells. Therefore, the present results can be considered in improving cancer-fighting methods.

Ceftazidime-assisted synthesis of ultrasmall chitosan nanoparticles for biofilm penetration and eradication of Pseudomonas aeruginosa

Pseudomonas aeruginosa (P. aeruginosa) infections present a grave threat to immunocompromised individuals, particularly those with cystic fibrosis due to the development of bacterial biofilms. In this study, we engineered self-assembling chitosan-ceftazidime nanoparticles (CSCE) capable of effectively penetrating biofilms and eradicating P. aeruginosa. The CSCE nanoparticles were synthesized through ionic cross-linking, combining negatively charged ceftazidime with positively charged chitosan, resulting in uniform nanoparticles measuring approximately 40 nm in diameter, exhibiting high dispersity and excellent biocompatibility. Remarkably, these nanoparticles exhibited significant inhibition of P. aeruginosa growth, reduced pyocyanin production, and diminished biofilm formation, achieving a maximum inhibition rate of 22.44%. Furthermore, in vivo investigations demonstrated enhanced survival in mice with abdominal P. aeruginosa infection following treatment with CSCE nanoparticles, accompanied by reduced levels of inflammatory cytokines Interleukin-6 (125.79 ± 18.63 pg/mL), Interleukin-17 (125.67 ± 5.94 pg/mL), and Tumor Necrosis Factor-α (135.4 ± 11.77 pg/mL). Critically, mice treated with CSCE nanoparticles showed no presence of bacteria in the bloodstream following intraperitoneal P. aeruginosa infection. Collectively, our findings highlight the potential of these synthesized nanoparticles as effective agents against P. aeruginosa infections.

Polyethylene glycol and chitosan functionalized manganese oxide nanoparticles for antimicrobial and anticancer activities

Biocompatible polymer-functionalized magnetic nanoparticles could offer promising applications in biomedical sciences. We fabricated polymer functionalized tri-manganese tetra oxide (Mn₃O₄) nanoparticles with the co-precipitation method and an octahedral crystal structure having a crystallite size of 10-17 nm was identified via XRD analyses. The SEM graph depicted the non-uniform and smooth surface of PEG-functionalized Mn₃O₄ NPs as compared to Mn₃O₄ and chitosan-coated Mn₃O₄ NPs. Elemental composition in the prepared sample was examined by EDX analysis. Various modes such as MnO, MnOH, OH, symmetric, and anti-symmetric of CH₂ attached to the spectrum of Mn₃O₄ NPs were observed with FTIR analysis. The magnetization factor decreased and increase the coreacivity and retentivity of surface functionalized Mn₃O₄-NPs was calculated via VSM analysis. In-vitro bioassay, antibacterial activity was tested against Escherichiacoli, Bacillus cereus, and anti-fungal activities against two Fusarium strains indicated clear antimicrobial activities. The MTT assay to examine the anticancer activity against the MCF-7 cancer cell line was performed and the T₁ MRI contrast agent demonstrated that PEG-coated Mn₃O₄ NPs exhibited anti-cancer activities. We propose that surface-functionalized magnetic NPs used for the treatment of cancer by using a remote controlled process of hyperthermia therapy.

Synthesis of single-walled carbon nanotubes functionalized with platinum nanoparticles to sense breast cancer cells in 4T1 model to X-ray radiation

In recent years, various types of radiosensitizers have been developed to address the challenges of cancer radiotherapy. Here, platinum-functionalized oxygenated single-walled carbon nanotubes (O-SWCNTs-Pt) coated with folic acid (FA) and bovine serum albumin (BSA) (O-SWCNTs-Pt-BSA-FA) were synthesized, characterized, and used as radiosensitizers to improve the therapeutic efficacy of X-rays in a mouse model of breast cancer (4T1) in vitro. The nanosensitizer was characterized by different techniques, such as transmission electron microscopy (TEM), selected area electron diffraction (SAED), dynamic light scattering (DLS), zeta potential, X-ray diffraction (XRD), ultraviolet-visible (UV-visible), and Fourier transform infrared (FTIR) spectrometry. The evaluation of cell viability with nanocarriers O-SWCNTs-BSA, O-SWCNTs-Pt-BSA, Pt-BSA-FA, and O-SWCNTs-Pt-BSA-FA is reported at the concentrations of 10, 30, and 90 μg/mL by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in the presence and absence of X-rays at 4 and 8 Gy. The results showed that administration of O-SWCNTs-BSA, O-SWCNTs-Pt-BSA, Pt-BSA-FA, and O-SWCNTs-Pt-BSA-FA + 8 Gy at a concentration of 90 μg/mL reduced survival by 75.31, 65.32, 67.35, and 60.35%, respectively. O-SWCNTs-Pt-BSA-FA has a hydrodynamic size of 88.57 nm and a surface charge of -29 mV, which indicates special stability. Compared with O-SWCNTs-BSA, O-SWCNTs-Pt-BSA, and Pt-BSA-FA, it has very strong cell-killing activity in the 4T1 cell line. It is also noteworthy that SWCNTs can act as a controlled release and delivery system for PtNPs due to their unique properties and easy penetration into biological membranes. As a result, the  new nanosensitizer may play a role in cancer treatment in conjunction with radiotherapy technology. Graphical abstract.

"Turn-on" fluorescent sensor for oleanolic acid based on o-phenyl-bridged bis-tetraphenylimidazole

Fluorescent sensors had been extensively applied on sensing various biomolecules effectively, but no fluorescent sensor for oleanolic acid was presented up to now. In this work, the first fluorescent sensor for oleanolic acid was designed and synthesized based on o-phenyl-bridged bis-tetraphenylimidazole (PTPI). PTPI was prepared by bridging two tetraphenylimidazole units and o-phenylenediamine via Schiff-base condensation in yield of 86%. PTPI showed high sensing selectivity for oleanolic acid among 26 biomolecules and ions. The blue fluorescence at 482 nm was enhanced by 4.5 times after sensing oleanolic acid in aqueous media. The fluorescence sensing ability of PTPI for oleanolic acid maintained stable in pH = 5-9. The detecting limitation was as low as 0.032 μM. The detecting mechanism was clarified as 1:1 binding stoichiometry by fluorescence Job's plot, mass spectrometry, ¹H nuclear magnetic resonance and fourier transform infrared spectroscopy. The detecting ability of PTPI for oleanolic acid was successfully used for paper test and real samples of grapes and Kuding tea with recoveries in the range of 96.0%-106.0%, indicating the good application potential for on-site detecting oleanolic acid in real samples of fruits and food.

Insight into catalytic activation of bisulfite for lomefloxacin degradation by simple composite of calcinated red mud

Antibiotic was detected in many environments, and it had posed a serious threat to human health. The advanced oxidation process has been considered an effective way to treat antibiotics. In this work, using industrial waste red mud (RM) as raw material, a series of modified RM (MRM-T; T donates the calcination temperature) was obtained via a facile calcination method and applied to activate sodium bisulfite (NaHSO₃) for the lomefloxacin (LOM) degradation. Among all MRM-T, MRM-700 exhibited superior catalytic activity, and approximately 89% of LOM (10 mg/L) was degraded at 30 min through the activation of NaHSO₃ ([NaHSO₃] = 0.5 g/L) by MRM-700 ([MRM-700] = 0.9 g/L). Moreover, the kinetic constant of LOM removal in the MRM-700/NaHSO₃ system (0.082 min^-1) was 16.4 times higher than that of the RM-raw/NaHSO₃ system (0.005 min^-1). The as-synthesized product of MRM-700 was characterized by N₂ adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectra. The result indicated that the catalyst possessed excellent pore structure, high specific area, and abundant Fe³⁺ sites, and the lattice of Fe₂O₃ was doped after calcination, both of which were favorable for the activation of NaHSO₃. The quenching experiment proved that •SO₄^- and •OH^- active species were produced in MRM-700/NaHSO₃ system, and •SO₄^- played a dominant role in LOM removal. In addition, the potential LOM degradation pathway was analyzed via UPLC-MS technology and density functional theory (DFT) calculation, and the toxicity of the treated LOM solution was tested by the culture of mung bean sprouts. This study not only provided a feasible strategy for the valuable use of RM to activate NaHSO₃ but also offered a cost-effective catalyst for the efficient removal of pollutants in wastewater.

Fabrication of hybrid covalent triazine framework-zinc ferrite spinel to uplift visible light-driven photocatalytic organic pollutant degradation

The tunability of porous covalent triazine frameworks (CTFs) can mitigate poor photostability and rapid hole-electron recombination. Herein, an excellent improvement of visible light-driven photocatalytic pollutant degradation was achieved using a hybrid semiconductor of covalent triazine framework-zinc ferrite spinel catalysts (CTF-ZnFe₂O₄). The as-prepared CTF-ZnFe₂O₄ composites were fabricated using a facile one-pot ionothermal method. The hybrid photocatalysts were identified using X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray (SEM-EDX), X-ray photoelectron spectrometer (XPS), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR), and UV-visible diffuse reflection spectroscopy (UV-vis DRS) characterizations. The analysis reveals that hybridization successfully ensued and altered the crystallinity structure, morphology, surface area, and bandgap energy of hybrid material. It was found that CTF-ZnFe₂O₄ 90:10 is very effective for the degradation of MB in a UV-vis light photocatalytic process with the efficiency of 95.4% and k_obs of 0.421 min^-1 for degradation of 50 mg/L MB with 0.5 g/L dosages for 120 min. Additionally, the scavenger study, effect of additional oxidants, and stability were performed for the practical application of a hybrid photocatalyst. CTF-ZnFe₂O₄ 90:10 shows outstanding pollutant degradation in sunlight irradiation and high stability with only a 5.2% reduction after a five-times sequential recycling process. Moreover, the photocatalytic mechanism of as-prepared CTF-ZnFe₂O₄ was mainly influenced by [Formula: see text] radical compared to [Formula: see text] and [Formula: see text] radicals. Overall, The as-prepared CTF-ZnFe₂O₄ shows significant potential to be utilized for photocatalytic wastewater treatment.

Superhydrophobic lignin-based multifunctional polyurethane foam with SiO2 nanoparticles for efficient oil adsorption and separation

Superhydrophobic polyurethane foam is one of the most promising materials for oil-water separation. However, there are only limited studies prepared matrix superhydrophobic foams as adsorbents. In this paper, SiO₂ modified by 1H, 1H, 2H, 2H-perfluorododecyl trichlorosilane (F-SiO₂) was added into the lignin-based foam matrix by a one-step foaming technique. The average diameter of F-SiO₂ was about 480 nm with an water contact angle (WCA) of 160.3°. The lignin-based polyurethane foam with F-SiO₂ had a superhydrophobic water contact angle of 151.3°. There is no obvious change in contact angle after 100 cycles of compression or after cutting and abrasion. Scanning electron microscopy (SEM) analysis showed that F-SiO₂ was distributed both on the surface and inside of the foam. The efficiency for oil-water separation reached 99 %. Under the light intensity of 1 kW/m², the surface temperature of the lignin-based foam rose to 77.6 °C. In addition, the foam exhibited self-cleaning properties and degraded within 2 h in an alcoholic alkali solution. Thus, in this study, we developed a novel matrix superhydrophobic lignin-based polyurethane foam with an excellent promise to be used as oil water separation adsorbents in industrial wastewater treatment and oil spill clean-up processes.

Electrochemical sensor based on a ZnO-doped graphitized carbon for the electrocatalytic detection of the antibiotic hydroxychloroquine. Application: tap water and human urine

Abstract

In December 2019, the world experienced a new coronavirus, SARS-CoV-2, causing coronavirus disease 2019 originating from Wuhan.The virus has crossed national borders and now affects more than 200 countries and territories. Hydroxychloroquine has been considered as a drug capable of treating COVID-19. The objective of this work is to establish a simple platform for electrocatalytic detection of hydroxychloroquine in human urine samples and pharmaceutical samples (tablets) using a ZnO@CPE sensor constructed by simple and inexpensive hydrothermal methods using a square wave voltammetry method. The best results are obtained in a PBS electrolyte with irreversible behavior of the hydroxychloroquine complement and controlled by diffusion coupled with absorption phenomena. The ZnO@CPE shifts the oxidation potential of hydroxychloroquine with the formation of a single very intense peak at the position of Epa = 0.5 V/(vs Ag/AgCl) with a shift is ΔEp = 0.1 V(vs Ag/AgCl) compared to the unmodified electrode. The obtained ZnO@CPE hybrid nanocomposite was characterized by different techniques and showed excellent electrocatalytic activity and higher active surface area compared to the bare carbon paste electrode. Under the optimized experimental conditions, the ZnO@CPE sensor showed good analytical performance for the determination of trace amounts of hydroxychloroquine, a wide linearity range from 10^-3 M to 0.8 × 10^-6 M with a very low detection limit in the range of 1.33 × 10^-7 M, satisfactory selectivity, acceptable repeatability and reproducibility. The calculated recovery and coefficient of variation for the two samples analyzed are very satisfactory, ranging from 97.6 to 102% and 1.2 to 2.3% respectively. The proposed applied method and the fabricated sensor offer the possibility to analyze traces of hydroxychloroquine in real human urine and water samples.

Graphical abstract

Strategy for the electro-oxidation reaction of hydroxychloroquine on the electro-catalytic surface of the ZnO@Carbon graphite electrode and real-time detection of hydroxychloroquine.

Structural growth of zinc oxide nanograins on carbon cloth as flexible electrochemical platform for hydroxychloroquine detection

Pharmaceutical pollution that imposes a health threat worldwide is making accurate and rapid detection crucial to prevent adverse effects. Herein, binder-free zinc oxide nanograins on carbon cloth (ZnO NGs@CC) have been synthesized hydrothermally and employed to fabricate a flexible electrochemical sensor for the quantification of hydroxychloroquine (HCQ) that is typical pharmaceutical pollution. The characteristics of ZnO NGs@CC were investigated by various in-depth electron microscopic, spectroscopic and electroanalytical approaches. Compared with the pristine CC platform, the ZnO NGs@CC platform exhibits superior electrochemical performance in detecting HCQ with a large oxidation current at a low over-potential of +0.92 V with respect to the Ag/AgCl (Sat. KCl) reference electrode. With the support of desirable characteristics, the fabricated ZnO NGs@CC-based electrochemical sensor for HCQ detection displays good performances in terms of wide sensing range (0.5-116 μM), low detection limit (0.09 μM), high sensitivity (0.279 μA μM^-1 cm^-2), and strong selectivity. By the resulting 3D hierarchical nanoarchitecture, ZnO NGs@CC has progressive structural advantages that led to its excellent electrochemical performance in sensing applications. Furthermore, the electrochemical sensor is employed to detect HCQ in biological and environmental samples and also achieves good recovery rates. Thus, the designed ZnO NGs@CC demonstrates admirable electrochemical activity toward HCQ real-time monitoring and would be an excellent electrochemical platform for HCQ sensing.

Construction of ANbO3 (A= Na, K)/f-carbon nanofiber composite: Rapid and real-time electrochemical detection of hydroxychloroquine in environmental samples

Hydroxychloroquine (HCQ) is a significant viral resistant drug widely acknowledged for its immunomodulatory and anti-inflammatory activities. To minimize the impact of HCQ residues on environmental pathways, exploring control measures is vital. In this regard, electrochemical sensing of HCQ using well-structured functional materials is advantageous. This work aims to provide an economical and sustainable route for the synthesis of ANbO₃ (A = Na,K) perovskites via a thymol-menthol-based natural deep eutectic solvent. The as-synthesized NaNbO₃ and KNbO₃ are pinned to functionalized carbon nanofibers (f-CNF) via an ultrasonication approach. Benefitting from the synergistic effect of rapid electron transfer and improved surface area, enhanced electrochemical activity for NaNbO₃@f-CNF/GCE is achieved. The fabricated NaNbO₃@f-CNF displays a LOD (DPV = 0.01 μM, i-t = 0.007 μM), wide dynamic range (DPV = 0.09-22.5 μM, i-t = 0.006-35 μM), outstanding selectivity, and reproducibility, proving feasible in real-time analysis with good recovery rates (±97.67-99.81%). The NADES-mediated preparation of perovskites evades the incorporation of traditional toxic solvents and yields atom-efficient ANbO₃ (A = Na,K) associated with green solvent templates. This validates the sustainable fabrication of electrode materials with reduced energy stipulations for detecting hazardous drug pollutants in the ecosystem.

Self assembled three dimensional β-Cu2V2O7 hierarchical flower decorated porous carbon: An efficient electrocatalyst for flutamide detection in biological and environmental samples

The serious situation mandates the use of anticancer drugs, which protect people all over the world from the growth of prostate cancer. In particular, excessive dosage and erroneous discharge of flutamide concentration cause make environmental pollution on the surface of the wastewater. In this study, the highly sensitive and selective electrochemical approach based on copper vanadium oxide decorated porous carbon (denoted as β-Cu₂V₂O₇/PC) composite modified glassy carbon electrode (GCE) has been developed and it was applied for sensitive detection of anticancer drug flutamide (FTM). Moreover, using the co-precipitation method, the flower-like β-Cu₂V₂O₇ hierarchical microstructure was synthesized, and through the wet chemical process, the β-Cu₂V₂O₇/PC composite was obtained. The resultant product was characterized by XRD, FTIR, RAMAN, XPS and structural morphology established by FESEM analysis. Besides that, the electrochemical characterization and properties were analyzed by cyclic voltammetry (CV) and amperometric (i-t) techniques. The β-Cu₂V₂O₇/PC/RDGCE had two linear ranges at 0.01-2.11 μM and 2.31-30.81 μM. The lower limits of detection and sensitivity were found at 0.62 nM (S/N = 3), and 24.33 μA μM^-1 cm^-2 respectively. The practicability test was applied for the determination of FTM in urine, blood serum and environmental aquatic fluid with satisfactory recovery obtained.

Application of Statistical Methods to Accurately Assess the Effect of Gamma Aluminum Oxide Nanopowder on the Hardness of Composite Materials with Polyester-Glass Recyclate

Polymer composites are materials that are used in many industries. Their wide application has a direct impact on the amount of post-production and post-consumer waste. The global problem with recycling, especially of fiber-reinforced polymeric materials, has prompted research into methods of their use. Previous research on composite materials with polyester-glass recyclate showed a decrease in mechanical properties. The construction material should have the highest mechanical properties. Based on the literature, it was found that the use of nanoadditives may have a positive effect on the parameters of the materials. The use of gamma aluminum nanopowder, in a small amount can significantly increase the mechanical properties of composites with polyester-glass recyclate, and thus can affect the application of these materials to structural elements. The article is devoted to the research on the hardness of composite materials with polyester-glass recyclate and gamma aluminum nanopowder. The main goal is to investigate the possibility of using a nanoadditive as a material, increasing the mechanical properties of composites with polyester-glass recyclate, so as to create a recycled material with the highest possible strength parameters. Hardness tests were performed using the Barcol method. For each composite material, 30 measurements were made in order to subject the results to a statistical analysis. Using parametric statistical tests it was shown that the obtained hardness values at the assumed level of statistical significance p_v = 0.05 for comparisons for the samples of the reference material (B0) do not differ by chance, while for the comparisons in the configurations of the reference material (B0) with the modified materials, (R10, A2, R10A2) they do not differ by accident. Studies have shown that the addition of 2% gamma aluminum nanopowder slightly lowers the hardness of a pure polyester-glass composite, but the same additive allows the hardness of composite materials to be increased with the addition of glass recyclate. This is of particular importance for the development of the optimal composition of polyester-glass composites with the addition of recyclate, which will have good strength properties and at the same time enable the reuse of composite waste.

Chitosan-CdS Quantum Dots Biohybrid for Highly Selective Interaction with Copper(II) Ions

Cadmium sulfide (CdS) quantum dots (QDs) were homogeneously embedded into chitosan (CTS), denoted as CdS@CTS, via an in situ hydrothermal method. The intact structure of the synthesized materials was preserved using freeze-drying. The materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, transmission electron microscopy, high-resolution TEM, scanning TEM, dispersive energy X-ray (EDX) for elemental analysis and mapping, Fourier transform infrared spectroscopy, nitrogen adsorption-desorption isotherms, thermogravimetric analysis, UV-vis spectroscopy, and diffuse reflectance spectroscopy (DRS). The synthesis procedure offered CdS QDs of 1-7 nm (average particle size of 3.2 nm). The functional groups of CTS modulate the in situ growth of CdS QDs and prevent the agglomeration of CdS QDs, offering homogenous distribution inside CTS. CdS@CTS QDs can also be used for naked-eye detection of heavy metals with high selectivity toward copper (Cu2+) ions. The mechanism of interactions between Cu2+ ions and CdS@CTS QDs were further studied.

Rapid electrochemical detection of MiRNA-21 facilitated by the excellent catalytic ability of Pt@CeO2 nanospheres

Pt@CeO2 nanospheres (NSs) were first synthesized by simply mixing Ce(NO3)3 and K2PtCl4 under the protection of pure argon at 70 °C for 1 h, which exhibited excellent catalytic ability toward hydrogen peroxide (H2O2). An electrochemical biosensor was successfully developed using Pt@CeO2 NSs as a capture probe for the ultra-sensitive and fast detection of miRNA-21, a new type of biomarker for disease diagnostics, especially for cancer. During the step-by-step construction process of the RNA sensor, Pt@CeO2 NSs were functionalized with streptavidin (SA) to obtain SA-Pt@CeO2 NSs through amide bonds. Gold nanoparticles (Au NPs) were electrodeposited on the surface of the glassy carbon electrode to improve the transmission capacity of electrons and provided Au atoms for fixing the thiolated capture probe (SH-CP) with a hairpin structure on the electrode via forming Au-S bonds. The target miRNA-21 specifically hybridized with SH-CP and opened the hairpin structure to form a rigid duplex so as to activate the biotin at the end of the capture probe. SA-Pt@CeO2 NSs were thus specially attached to the electrode surface through the biotin-streptavidin affinity interaction, finally leading to the significant signal amplification. The ultra-sensitive and rapid detection of miRNA-21 was finally realized as expected benefiting from the excellent catalytic ability of Pt@CeO2 NSs toward H2O2 in a wide linear concentration range from 10 fM to 1 nM with the detection limit as low as 1.41 fM. The results achieved with this new RNA sensor were quite satisfactory during the blood sample analysis.

Morphology Effect of Bismuth Vanadate on Electrochemical Sensing for the Detection of Paracetamol

Morphology-control, as a promising and effective strategy, is widely implemented to change surface atomic active sites and thus enhance the intrinsic electrocatalytic activity and selectivity. As a typical n-type semiconductor, a series of bismuth vanadate samples with tunable morphologies of clavate, fusiform, flowered, bulky, and nanoparticles were prepared to investigate the morphology effect. Among all the synthesized samples, the clavate shaped BiVO₄ with high index facets of (112), (301), and (200) exhibited reduced extrinsic pseudocapacitance and enhanced redox response, which is beneficial for tackling the sluggish voltammetric response of the traditional nanoparticle on the electrode surface. Benefiting from the large surface-active area and favorable ion diffusion channels, the clavate shaped BiVO₄ exhibited the best electrochemical sensing performance for paracetamol with a linear response in the range of 0.5–100 µmol and a low detection limit of 0.2 µmol. The enhanced electrochemical detection of paracetamol by bismuth vanadate nanomaterials with controllable shapes indicates their potential for applications as electrochemical sensors.