Silver-palladium bimetallic nanoparticles stabilized by elm pod polysaccharide with peroxidase-like properties for glutathione detection and photothermal anti-tumor ability.

Noble metal nanoparticles show good application prospects in biosensors and anti-tumor drug research. Herein, the near-spherical silver­palladium bimetallic nanoparticles supported by elm pod polysaccharide (EPP-AgPd1.5 NPs) were prepared by using the elm pod polysaccharide (EPP). EPP acts as a stabilizer and reducing agent due to its water solubility and weak reducing ability. The particle size of EPP-AgPd1.5 NPs was 33.6 ± 5.5 nm. In addition, EPP-AgPd1.5 NPs had peroxidase-like activity to catalyze 3,3',5,5'-tetramethylbenzidine (TMB) to oxidized TMB by catalyzing H2O2 to OH. Based on the peroxidase-like activity of EPP-AgPd1.5 NPs, a method for detecting glutathione was established, and the detection limit and linear range of glutathione concentration were 0.279 µM and 0-400 µM, respectively. More importantly, the photothermal conversion efficiency of EPP-AgPd1.5 NPs reached 39.7 %, and their inhibition rate in HeLa cells reached 69.9 %. Silver­palladium bimetallic nanoparticles stabilized by EPP had good performance in glutathione detection and anti-tumor drugs.

Vancomycin-Stabilized Platinum Nanoparticles with Oxidase-like Activity for Sensitive Dopamine Detection.

The development of efficient, reliable, and sensitive dopamine detection methods has attracted much attention. In this paper, vancomycin-stabilized platinum nanoparticles (Van-Ptn NPs, n = 0.5, 1, 2) were prepared by the biological template method, where n represented the molar ratio of vancomycin to Pt. The results show that Van-Pt2 NPs had oxidase-like activity and peroxidase-like activity, and the mechanism was due to the generation of reactive oxygen 1O2 and OH. Van-Pt2 NPs exhibited good temperature stability, storage stability, and salt solution stability. Furthermore, Van-Pt2 NPs had almost no cytotoxicity to A549 cells. More importantly, the colorimetric detection of DA in human serum samples was performed based on the oxidase-like activity of Van-Pt2 NPs. The linear range of DA detection was 10-700 µM, and the detection limit was 0.854 µM. This study establishes a rapid and reliable method for the detection of dopamine and extends the application of biosynthetic nanoparticles in the field of biosensing.

Platinum Palladium Bimetallic Nanozymes Stabilized with Vancomycin for the Sensitive Colorimetric Determination of L-cysteine.

Many diseases in the human body are related to the level of L-cysteine. Therefore, it is crucial to establish an efficient, simple and sensitive platform for L-cysteine detection. In this work, we synthesized platinum palladium bimetallic nanoparticles (Van-Ptm/Pdn NPs) using vancomycin hydrochloride (Van) as a stabilizer, which exhibited high oxidase-like catalytic activity. In addition, the catalytic kinetics of the Van-Pt1/Pd1 NPs followed the typical Michaelis-Menten equation, exhibiting a strong affinity for 3,3',5,5'-tetramethylbenzidine substrates. More importantly, we developed a simple and effective strategy for the sensitive colorimetric detection of L-cysteine using biocompatible Van-Pt1/Pd1 NPs. The detection limit was low, at 0.07 µM, which was lower than the values for many previously reported enzyme-like detection systems. The colorimetric method of the L-cysteine assay had good selectivity. The established method for the detection of L-cysteine showed promise for biomedical analysis.

Biocompatible Palladium Nanoparticles Prepared Using Vancomycin for Colorimetric Detection of Hydroquinone.

Hydroquinone poses a major threat to human health and is refractory to degradation, so it is important to establish a convenient detection method. In this paper, we present a novel colorimetric method for the detection of hydroquinone based on a peroxidase-like Pd nanozyme. The vancomycin-stabilized palladium nanoparticles (Van-Pdn NPs, n = 0.5, 1, 2) were prepared using vancomycin as a biological template. The successful synthesis of Van-Pdn NPs (n = 0.5, 1, 2) was demonstrated by UV-vis spectrophotometry, transmission electron microscopy, and X-ray diffraction. The sizes of Pd nanoparticles inside Van-Pd0.5 NPs, Van-Pd1 NPs, and Van-Pd2 NPs were 2.6 ± 0.5 nm, 2.9 ± 0.6 nm, and 4.3 ± 0.5 nm, respectively. Furthermore, Van-Pd2 NPs exhibited excellent biocompatibility based on the MTT assay. More importantly, Van-Pd2 NPs had good peroxidase-like activity. A reliable hydroquinone detection method was established based on the peroxidase-like activity of Van-Pd2 NPs, and the detection limit was as low as 0.323 µM. Therefore, vancomycin improved the peroxidase-like activity and biocompatibility of Van-Pd2 NPs. Van-Pd2 NPs have good application prospects in the colorimetric detection of hydroquinone.

Pd nanoparticles stabilized by bitter gourd polysaccharide with peroxidase properties for H2O2 detection.

The development of nanozymes using noble metal nanoparticles to replace natural peroxidase in bio-related detection has been gain great interest. Noble metal nanoparticles with small size have large specific surface area. However, small noble metal nanoparticles tend to aggregate without stabilizer. In this paper, small Pd nanoparticles (3-6 nm) stabilized by bitter gourd polysaccharide (Pdn-BGP NPs) were prepared by using bitter gourd polysaccharide as reducing agent and stabilizing agent. Pd25-BGP NPs had peroxidase-like catalytic property. And the catalytic kinetics of Pd25-BGP NPs towards substrates conformed to the Michaelis-Menten equation. Furthermore, a method was established to detect H2O2 using Pd25-BGP NPs. The linear range and detection limit of this method was 20-320 µM and 2.04 µM, respectively. Finally, Pd25-BGP NPs had good biocompatibility when the concentration was less than 80 µg/mL. The prepared Pd nanoparticles with high stability showed their good prospect in H2O2 detection.

Properties of the "Z"-Phase in Mn-Rich P2-Na0.67 Ni0.1 Mn0.8 Fe0.1 O2 as Sodium-Ion-Battery Cathodes.

P2 layered oxides have attracted more and more attention as cathode materials of high-power sodium-ion batteries (SIBs). During the charging process, the release of sodium ions leads to layer slip, which leads to the transformation of P2 phase into O2 phase, resulting in a sharp decline in capacity. However, many cathode materials do not undergo P2 -O2 transition during charging and discharging, but form a "Z" phase. It is proved that the iron-containing compound Na0.67 Ni0.1 Mn0.8 Fe0.1 O2 formed the "Z" phase of the symbiotic structure of the P phase and O phase during high-voltage charging through ex-XRD and HAADF-STEM. During the charging process, the cathode material undergoes a structural change of P2 -OP4 -O2 . With the increase of charging voltage, the O-type superposition mode increases to form an ordered OP4 phase, and the P2 -type superposition mode disappears after further charging to form a pure O2 phase. 57 Fe-Mössbauer spectroscopy revealed that no migration of Fe ions is detected. The O-Ni-O-Mn-Fe-O bond formed in the transition metal MO6 (M = Ni, Mn, Fe) octahedron can inhibit the elongation of the Mn-O bond and improve the electrochemical activity so that P2-Na0.67 Ni0.1 Mn0.8 Fe0.1 O2 has an excellent capacity of 172.4 mAh g-1 and a coulombic efficiency close to 99% at 0.1C.

The Mn-modified porphyrin metal-organic framework with enhanced oxidase-like activity for sensitively colorimetric detection of glutathione.

The selective detection of glutathione (GSH) has been used as important colorimetric probe for human health. Herein, we used a facile method to synthesize manganese ions modified porphyrin metal-organic framework (PCN-224-Mn) with a size of 125.7 ± 14.2 nm and zeta potential of -3.9 ± 0.5 mV. We showed that PCN-224-Mn catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the absence of H2O2, resulting in a blue-colored oxidized TMB (oxTMB) that exhibits oxidase-like activity. Furthermore, a simple colorimetric detection method for GSH was developed based on the oxidase-like activity of PCN-224-Mn. This method shows wide linear detection range of 0.5-60 µM for GSH with a much lower detection limit of 0.233 µM. Finally, the recovery of colorimetric sensor of PCN-224-Mn suggests its great potential as a biosensor. As the catalytically active site, the manganese porphyrin unit plays a major role in the oxidase-like property and detection ability of PCN-224-Mn. Our data suggest that GSH detection method using PCN-224-Mn has great potential in multiple applications in the future.

Green synthesis of Ag nanoparticles using elm pod polysaccharide for catalysis and bacteriostasis.

The green synthesis of silver nanoparticles (Ag NPs) for catalysis and biological applications has gained great interest. Natural elm pods are a type of food that possesses anti-inflammatory and pain-relieving effects. In this study, elm pod polysaccharide (EPP) was extracted from elm pods using hot water extraction for the first time. Biocompatible EPP-stabilized silver nanoparticles (EPP-Agn NPs) were prepared by using a green synthesis method. The EPP-Ag25 NPs had a hydrodynamic size of 40.9 nm and a highly negative surface charge of -27.4 mV. Furthermore, EPP-Ag25 NPs exhibited high catalytic activity for the reduction of 4-nitrophenol, and the catalytic reaction followed a pseudo-first order kinetic equation. More importantly, the inhibition rate of EPP-Ag25 NPs on Escherichia coli was 71 % when samples were treated with an 808 nm laser. Besides, EPP-Agn NPs effectively inhibited the proliferation of tumor cells irradiated by an 808 nm laser. The improved performance of EPP-Agn NPs was due to the good stability of EPP. Taken together, EPP-Agn NPs had good stability, catalytic activity, antibacterial and antitumor ability under laser irradiation. EPP is a good stabilizer for many nanoparticles which have broad applications in the field of catalysis and biomedicine in the future.

Biomineralized synthesis of palladium nanoflowers for photothermal treatment of cancer and wound healing.

Photothermal therapy uses photothermal agents (PTAs) to convert light energy to heat energy under near-infrared light to kill local tumors in cancer patients or speed up wound healing in diabetic patients. However, it is difficult to achieve high photothermal conversion efficiency for most of PTAs. Herein, daptomycin (Dap) micelles-stabilized palladium nanoflowers (Dap-PdNFs) were prepared for the first time. The palladium nanoflowers (PdNFs) inside of the Dap-PdNFs were 106 nm. The temperature of the Dap-PdNFs solution quickly rose from 26.8 °C to 52.0 °C within 10 min under irradiation with high photothermal conversion efficiency up to 38%. In addition, the cell viability of HeLa cells and HT-29 cells of Dap-PdNFs exceeded 95% in the absence of near-infrared light, indicating that Dap-PdNFs had good biocompatibility. Meanwhile, the inhibition rate of Dap-PdNFs on HeLa cells was as high as 71.2% under irradiation of 808 nm near-infrared light. More importantly, Dap-PdNFs had a good healing effect on wounds of diabetic mice under irradiation of 808 nm near-infrared light. In short, this research provides a facile method for the application of Dap-PdNFs in safe and efficient tumor treatment and wound healing.

Facile Solvothermal Synthesis of CuCo2S4 Yolk-Shells and Their Visible-Light-Driven Photocatalytic Properties.

In this present work, we synthesized a yolk-shell shaped CuCo2S4 by a simple anion exchange method. The morphological and structural properties of the as-synthesized sample were characterized using X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (UV-vis DRS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The SEM and TEM results confirmed that the uniform yolk-shell structure was formed during the solvothermal process. The band gap was about 1.41 eV, which have been confirmed by UV⁻vis DRS analysis. The photocatalytic property was evaluated by the photocatalytic degradation of methylene blue (MB) dye as a target pollutant under the visible-light irradiation. The experimental results confirmed the potential application of yolk-shell shape CuCo2S4 in visible-light photocatalytic applications.