Colorimetric determination of glutathione in human serum and cell lines by exploiting the peroxidase-like activity of CuS-polydopamine-Au composite.

In this study, we developed a simple colorimetric approach to detect glutathione (GSH). The proposed approach is based on the ability of CuS-PDA-Au composite material to catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to ox-TMB to induce a blue color with an absorption peak centered at 652 nm. However, the introduction of GSH can result in a decrease in oxidized TMB; similarly, it can combine with Au nanoparticles (Au NPs) on the surface of CuS-PDA-Au composite material. Both approaches can result in a fading blue color and a reduction of the absorbance at 652 nm. Based on this above, we proposed a technique to detect GSH quantitatively and qualitatively through UV-Vis spectroscopy and naked eye, respectively. This approach demonstrates a low detection limit of 0.42 µM with a broad detection range of 5 × 10-7-1 × 10-4 M with the assistance of UV-Vis spectroscopy. More importantly, this approach is convenient and rapid. This method was successfully applied to GSH detection in human serum and cell lines. Graphical abstract A colorimetric approach has been developed by exploiting the peroxidase-like activity of CuS-polydopamine-Au composite for sensitive glutathione detection.

Fluorescence and magnetic nanocomposite Fe3O4@SiO2@Au MNPs as peroxidase mimetics for glucose detection.

In this paper, multifunction nanoparticles (MNPs), Fe3O4@SiO2@Au MNPs, with properties of superparamagnetism, fluorescence and peroxidase-like catalytic activity were synthesized in the aqueous phase. The synthesized composites were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier translation infrared spectrum (FT-IR) and fluorometer. The results show that the multifunctional nanomaterials have good magnetic and fluorescence properties. Then, the mimetic properties of this material were investigated. The as-synthesized Fe3O4@SiO2@Au MNPs exhibited the best catalytic activity for peroxidase substrate 3,3,5,5-tetramethylbenzidine (TMB) at the reaction temperature of 70 °C and pH of 3. Compared with free Fe3O4 MNPs and BSA-Au nanoclusters (NCs), the composites have better catalytic activity at higher temperature and lower pH, indicating that Fe3O4@SiO2@Au MNPs can work in more severe environment. In practical application, we have successfully established the colorimetric method for the detection of H2O2 and glucose with the detection range of 1 × 10-6 ∼ 4 × 10-5 M and 5 × 10-6 ∼ 3.5 × 10-4 M, and the detection limit of 6 × 10-7 M and 3.5 × 10-6 M, respectively. The method was also successfully applied in the detection of real samples. Furthermore, since the fluorescence of Fe3O4@SiO2@Au MNPs was quenched by H2O2, a method for the visual detection of glucose was established.

Photothermal and ferroptosis synergistic therapy for liver cancer using iron-doped polydopamine nanozymes.

An innovative nanozyme, iron-doped polydopamine (Fe-PDA), which integrates iron ions into a PDA matrix, conferred peroxidase-mimetic activity and achieved a substantial photothermal conversion efficiency of 43.5 %. Fe-PDA mediated the catalysis of H2O2 to produce toxic hydroxyl radicals (•OH), thereby facilitating lipid peroxidation in tumour cells and inducing ferroptosis. Downregulation of solute carrier family 7 no. 11 (SLC7A11) and solute carrier family 3 no. 2 (SLC3A2) in System Xc- resulted in decreased intracellular glutathione (GSH) production and inactivation of the nuclear factor erythroid 2-related factor 2 (NRF2)-glutathione peroxidase 4 (GPX4) pathway, contributing to ferroptosis. Moreover, the application of photothermal therapy (PTT) enhanced the effectiveness of chemodynamic therapy (CDT), accelerating the Fenton reaction for targeted tumour eradication while sparing adjacent non-cancerous tissues. In vivo experiments revealed that Fe-PDA significantly hampered tumour progression in mice, emphasizing the potential of the dual-modality treatment combining CDT and PTT for future clinical oncology applications.

Mn3O4 Nanozyme Loaded Thermosensitive PDLLA-PEG-PDLLA Hydrogels for the Treatment of Inflammatory Bowel Disease.

When reactive oxygen species (ROS) accumulate in the body, they can lead to inflammatory bowel disease (IBD) through their oxidative damages to DNA, proteins, and lipids. In this study, a thermosensitive hydrogel-based nanozyme was developed to treat IBD. We first synthesized a manganese oxide (Mn3O4) nanozyme with multienzyme activity followed by physically loading with a thermosensitive hydrogel poly(d,l-lactide)-poly(ethylene glycol)-poly(d,l-lactide)-based triblock copolymer (PDLLA-PEG-PDLLA). Then, a mouse model based on the inducement of dextran sulfate sodium (DSS) was built to assess the ROS targeting, scavenging, as well as anti-inflammatory ability of Mn3O4 nanozymes-loaded PDLLA-PEG-PDLLA (MLPPP). Because of the sharp gelation behavior of PDLLA-PEG-PDLLA in body temperature, the MLPPP nanozyme can easily target the inflamed colon after colorectal administration. Following the formation of a physical protection barrier and sustained release of manganese oxide nanozymes that had diverse enzymatic activities and can effectively scavenge ROS, the administration of the MLPPP nanozyme had a high efficacy for treating colitis mice; importantly, after the treatment with this novel nanoformulation, the levels of the pathological indicators in colons as well as in sera of colitis mice were even comparable to healthy mice. Therefore, the MLPPP nanozyme has a potential application for nanotherapy of IBD and would have great clinical translation prospects.

Machine learning-assisted Te-CdS@Mn3O4 nano-enzyme induced self-enhanced molecularly imprinted ratiometric electrochemiluminescence sensor with smartphone for portable and visual monitoring of 2,4-D.

Here, a novel and portable machine learning-assisted smartphone-based visual molecularly imprinted ratiometric electrochemiluminescence (MIRECL) sensing platform was constructed for highly selective sensitive detection of 2,4-Dichlorophenoxyacetic acid (2,4-D) for the first time. Te doped CdS-coated Mn3O4 (Te-CdS@Mn3O4) with catalase-like activity served as cathode-emitter, while luminol as anode luminophore accompanied H2O2 as co-reactant, and Te-CdS@Mn3O4 decorated molecularly imprinted polymers (MIPs) as recognition unit, respectively. Molecular models were constructed and MIP band and binding energies were calculated to elucidate the luminescence mechanism and select the best functional monomers. The peroxidase activity and the large specific surface area of Mn3O4 and the electrochemical effect can significantly improve the ECL intensity and analytical sensitivity of Te-CdS@Mn3O4. 2,4-D-MIPs were fabricated by in-situ electrochemical polymerization, and the rebinding of 2,4-D inhibits the binding of H2O2 to the anode emitter, and with the increase of the cathode impedance, the ECL response of Te-CdS@Mn3O4 decreases significantly. However, the blocked reaction of luminol on the anode surface also reduces the ECL response. Thus, a double-reduced MIRECL sensing system was designed and exhibited remarkable performance in sensitivity and selectivity due to the specific recognition of MIPs and the inherent ratio correction effect. Wider linear range in the range of 1 nM-100 µM with a detection limit of 0.63 nM for 2,4-D detection. Interestingly, a portable and visual smartphone-based MIRECL analysis system was established based on the capture of luminescence images by smartphones, classification and recognition by convolutional neural networks, and color analysis by self-developed software. Therefore, the developed MIRECL sensor is suitable for integration with portable devices for intelligent, convenient, and fast detection of 2,4-D in real samples.

Application of magnetic hydroxyapatite nanoparticles for solid phase extraction of plasmid DNA.

We developed a facile method for plasmid DNA (pDNA) extraction from crude Escherichia coli lysate using magnetic hydroxyapatite nanoparticles (MHapNPs) in the presence of polyethylene glycol (PEG)/NaCl. DNA condensation induced by PEG/NaCl is a prerequisite for achieving pronounced DNA recovery. The quality and quantity of MHapNP-purified pDNA under optimal binding buffer conditions (0.5 volume of 20% PEG 8000/2M NaCl) were comparable to those obtained using organic solvents or commercial kits. This MHapNP technique is rapid, simple, cost-effective, and environmentally friendly and has the potential to extract DNA from other cell lysates.

Mo3Se4 nanoparticle with ROS scavenging and multi-enzyme activity for the treatment of DSS-induced colitis in mice.

Ulcerative colitis (UC), as a most common inflammatory bowel disease (IBD), has become a global public health concern. Exploring novel method of treating UC is urgent and necessary. Recently, nanozyme with excellent antioxidant properties may be one useful therapeutic strategy. In this study, a two-dimensional transition metal chalcogenide (TMCs) nano flake and polyethylene glycol (PEG) modified Mo3Se4 nano flakes (PMNFs) was synthesized, which had multi-enzyme activity, including peroxidase, glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT). The inhibition effect of PMNFs on sodium dextran sulfate (DSS)-induced colitis was explored. UC was effectively inhibited by PMNFs in this work. PMNFs significantly reduced disease activity index (DAI) score, including weight loss, colon shorten and histopathological abnormalities. The possible mechanism of PMNFs-attenuated colitis was investigated. The results showed that PMNFs reversed DSS-induced oxidative damage, and the antioxidant pathway Nrf2-keap1 signal was activated by PMNFs. Moreover, PMNFs suppressed the expression of pro-inflammatory factors including IL-1ß, TNF-α, IFN-ß and IL-6 via the inactivation of TLR4/NF-κB pathway in DSS-induced colitis and LPS-treated macrophage. Furthermore, PMNFs treatment prevented the reduction of tight junction proteins (ZO-1, occludin, and claudin-1) and mucin-2 (MUC-2) as well as the up-regulation of epithelial apoptosis caused by DSS. These findings demonstrate that the PMNFs against DSS-induced colitis due to its prevention on oxidative damage, inflammation, and intestine barrier breakdown. Thus, PMNFs have a potential application in the treatment of various oxidative stress or inflammation-related diseases.

Deep learning-assisted smartphone-based molecularly imprinted electrochemiluminescence detection sensing platform: Protable device and visual monitoring furosemide.

A novel, portable, and smartphone-based molecularly imprinted polymer electrochemiluminescence (MIP-ECL) sensing platform was constructed for sensitive and selective determination of furosemide (FSM). In this platform, MoSe2 nanoparticles/starch-derived biomass carbon (MoSe2/BC) nanocomposites as imprinted material, lucigenin (Luc) as the energy donor, CdS quantum dots (CdS QDs) were used as the luminophore (energy acceptor), and molecularly imprinted polymer (MIP) as the specificity recognition element to construct a MIP-ECL sensing system based on electroluminescence resonance energy transfer (ECL-RET) mechanism, which enhanced the sensitivity and the specificity of this system. Imprinted materials were characterized by SEM, TEM, XRD, FT-IR, etc. and the recognition performance of MIP was characterized using CV, EIS, and ECL methods. The elution and re-sorption of template molecules can be used as a switch to control ECL based on the signal that can be quenched by FSM. Interestingly, deep learning based on convolutional neural networks realizes batch processing of ECL signals. Additionally, this developed MIP-ECL method was established by using the traditional ECL analyzer detector for the assay of FSM with a detection limit of 4 nM in the range of 0.010 µM-100 µM. Besides, the consumer smartphone sensing platform based on deep learning showed an outstanding linear response between the R-value of the picture and the concentration of furosemide in the range of 1-70 µM with a detection limit of 0.25 µΜ, which is much lower than that the reported for other detection methods. More importantly, due to the transferability of deep learning, the smartphone-based MIP-ECL systems can facilitate the real-time monitoring of biochemical analytes in multiple fields.

A novel molecularly imprinted electrochemical sensor based on graphene quantum dots coated on hollow nickel nanospheres with high sensitivity and selectivity for the rapid determination of bisphenol S.

In this paper, a novel molecularly imprinted electrochemical sensor (MIECS) based on a glassy carbon electrode (GCE) modified with graphene quantum dots (GQDs) coated on hollow nickel nanospheres (hNiNS) for the rapid determination of bisphenol S (BPS) was proposed for the first time. HNiNS and GQDs as electrode modifications were used to enlarge the active area and electron-transport ability for amplifying the sensor signal, while molecularly imprinted polymer (MIP) film was electropolymerized by using pyrrole as monomer and BPS as template to detect BPS via cyclic voltammetry (CV). Scanning electron microscope (SEM), energy-dispersive spectrometry (EDS), CV and differential pulse voltammetry (DPV) were employed to characterize the fabricated sensor. Experimental conditions, such as molar ratio of monomer to template, electropolymerization cycles, pH, incubation time and elution time were optimized. The DPV response of the MIECS to BPS was obtained in the linear range from 0.1 to 50µM with a low limit of detection (LOD) of 0.03µM (S/N = 3) under the optimized conditions. The MIECS exhibited excellent response towards BPS with high sensitivity, selectivity, good reproducibility, and stability. In addition, the proposed MIECS was also successfully applied for the determination of BPS in the plastic samples with simple sample pretreatment.