The age of vanadium-based nanozymes: Synthesis, catalytic mechanisms, regulation and biomedical applications

Nanomaterials with enzyme-mimic(nanozyme) activity have garnered considerable attention as a potential alternative to natural enzymes, thanks to their low preparation cost, high activity, ease of preservation, and unique physicochemical properties. Vanadium(V) is a transition metal that integrates the benefits of valence-richness, low cost, and non-toxicity, making it a desirable candidate for developing a range of emerging nanozymes. In this review, we provide the first systematic summary of recent research progress on V-based nanozymes. First, we summarize the preparation of V-based nanozymes using both top-down and bottom-up synthesis methods. Next, we review the mechanism of V-based nanozymes that mimic the activity of various enzymes. We then discuss methods for regulating V-based nanozyme activity, including morphology, size, valence engineering, defect engineering, external triggering, and surface engineering. Afterward, we outline various biomedical applications, including therapeutic, anti-inflammatory, antibacterial, and biosensing. Finally, we prospect the challenges and countermeasures for V-based nanozymes based on their development. By summarizing recent research progress on V-based nanozymes, we hope to provide useful insights for researchers to further explore their potential applications and overcome their existing challenges.

Determination and Analysis of Amino Acid Content in Maca from Different Habitats and Varieties

[Objectives]To determine and analyze amino acid content in Maca from different habitats and varieties.[Methods]Maca from two habitats and three colors were selected and a kind of turnip commonly used was to fake Maca.After optimizing the hydrolysis conditions,100 mg Maca samples were hydrolyzed in the concentration of 6 mol/L hydrochloric acid at 110℃for 24 h.The content range of amino acids in each sample was detected by HPLC.[Results]The average total content of amino acids in Maca was 9.52 g/100 g.Yunnan yellow Maca contained 16 kinds of amino acids,including 7 kinds of human essential amino acids,accounting for 17.2%of the total amino acids while Yunnan purple Maca held 16 kinds of amino acids,counting 7 kinds of human essential amino acids,accounting for 16.5%of the total amino acids.The amino acid ratio coefficient method also showed that the two kinds of Maca had higher nutritional value than the others.15 kinds of amino acids were detected in Yunnan black Maca,including 6 kinds of essential amino acids,accounting for 9.60%of the total amino acids.Among amino acids in Yunnan Maca,the highest content was Arg.A total of 12 kinds of amino acids,together with 6 essential human amino acids,were determined in Peru black Maca,accounting for 11.6%of the total amino acids.In Peru black Maca the highest concentration of amino acid was Pro.It was noteworthy that the amino acid species were comprehensive in Maca,and high level of amino acids resulted in high nutritional value.Its specific amino acid composition ratio was obviously different from Turnip,the counterfeit goods to deceive customers.[Conclusions]The method of automatic amino acid analyzer is simple and accurate,and can be used for the identification and content determination of amino acids in Maca as amino acid is an essential nutrient in Maca.

Identification and screening of cardiac glycosides in Streptocaulon griffithii using an integrated data mining strategy based on high resolution mass spectrometry

The present study was designed to develop a practical strategy to tackle the problem of lacking standard compounds and limited references for identifying structure-related compounds in Streptocaulon griffithii Hook. f., especially those in trace concentrations, with a focus on antitumor activity. The cardiac glycosides(CGs)-enriched part was determined using in vitro bioactive assays in three cancer cell lines and then isolated using macroporous resins. The MS and MS/MS data were acquired using a high performance liquid chromatography coupled with hybrid quadrupole-time of flight(HPLC-Q-TOF-MS) system. To acquire data of trace compound in the extract, a multiple segment program was applied to modify the HPLC-Q-TOF-MS method. A mass defect filter(MDF) approach was employed to make a primary MS data filtration. Utilizing a MATLAB program, the redundant peaks obtained by imprecise MDF template calculated with limited references were excluded by fragment ion classification, which was based on the ion occurrence number in the MDF-filtered total ion chromatograms(TIC). Additionally, the complete cleavage pathways of CG aglycones were proposed to assist the structural identification of 29 common fragment ions(CFIs, ion occurrence number ≥ 5) and diagnostic fragment ions(DFIs, ion occurrence number < 5). As a result, 30 CGs were filtered out from the MDF results, among which 23 were identified. This newly developed strategy may provide a rapid and effective tool for identifying structure-related compounds in herbal medicines.

Synergistic effects of CdS in sodium titanate based nanostructures for hydrogen evolution

In this paper, nanotubes and nanoribbons of sodium titanate structures were synthesized via hydrothermal methods in alkaline solution. CdS decorated titanate nanotubes and nanoribbons were therefore constructed for exploring the performance of hydrogen evolution and synergistic effect of CdS based titanate structures. CdS decorated titanate nanotubes and nanoribbons were characterized by high resolution transmission electron microscopy （HRTEM）, X-ray diffraction （XRD）, UV-vis, Brunauer- Emmett-Teller （BET） and X-ray photoelectron spectroscopy （XPS） measurements. CdS encapsuled in titanate nanotubes （CdS-ETNTs） showed the best capacity of H2 evolution by water splitting and stability than that from the other two structures, i.e., CdS doped titanate nanotubes （CdS-DTNTs） and CdS doped titanate nanoribbons （CdS-DTNRs）, which could be explained by the synergistic effect of decorated CdS with sodium titanate structures and confinement effect of CdS nanoparticles encapsuled inside

Effects of gold core size on regulating the performance of doxorubicin-conjugated gold nanoparticles

Studies on the influence of one critical parameter （e.g., size）, targeting a specific disease, while keeping other factors unchanged, are important for improving understanding and application of the molecular design of biomedical nanomaterials. In this study, we used doxorubicin （Dox）-conjugated gold nanoparticles （GNPs） to investigate the effects of the size of the gold core （10, 20, or 60 nm） on the performance of their conjugates. We found that all three conjugates differed slightly in their physicochemical properties, facilitating a direct and accurate assessment of the size effects of GNP-Dox conjugates on their in vitro and in vivo performance. The cytological properties （the cell penetration rate and efficiency, as well as the cytotoxicity） and antitumor performance （the intratumoral penetration, treatment efficacy, and biodistribution） were highly correlated to the size of the inorganic core. Among all test groups, although the conjugate with a 60-nm gold core had the highest drug loading and release efficiency, the conjugate with a 10-nm gold core displayed the best antitumor efficacy toward the liver cancer models. This was because it showed the deepest tumor permeability and the highest tumor cell-killing ability of Dox transported by the relatively small GNPs. This study provides important evidence for better understanding the effect of size on in vitro and in vivo properties of potential therapeutic nanosystems and their structure design.

Noninvasive Detection and Imaging of Matrix Metalloproteinases for Cancer Diagnosis

Matrix metalloproteinases(MMPs)are important cancer biomarkers and the sensitive detection of MMPs is of great importance to improve clinical diagnosis and therapy of cancer at its early stage.Molecular imaging,including fluorescent optical imaging,radiolabeled imaging,and magnetic resonance imaging,is a powerful tool to visualize and characterize biological processes at the cellular and molecular level.The recognition of MMPs via imaging strategies by utilizing MMP-responsive probes has been a hot pursuit in recent years.Probes designed for MMP detection commonly have two features:(1)off-thenon state in detection signal response to the appearance of MMPs,which has been applied in optical imaging and magnetic resonance imaging;(2)specific retention upon sensing MMPs,which has been applied in radiolabeled imaging.The development of theory and technology in the field of biomarker probes will be beneficial to the accurate diagnosis and effective treatment of cancer.

Two new ortho benzoquinones from Uncaria rhynchophylla

The present study was designed to determine the chemical constituents of the stems and hooks of Uncaria rhynchophylla. The chemical constituents were isolated and purified from CH_2Cl_2 fraction by chromatography. Their structures were elucidated by spectroscopic analyses. Their cytotoxicity was tested using MTT method. Two new ortho benzoquinones, 3-diethylamino-5-methoxy-1, 2-benzoquinone(1) and 3-ethylamino-5-methoxy-1, 2-benzoquinone(2), together with a known compound isorhynchophyllic acid(3) were isolated from U. rhynchophylla. These compounds were evaluated for their cytotoxicity against cancer cells A549, Hep G2 and A2780. Compounds 1 and 2 were new ortho benzoquinones and showed weak antiproliferative activities on A549, Hep G2 and A2780 cells. Compound 3 significantly inhibited the proliferation of A549, Hep G2 and A2780 cells with IC_(50) values being 5.8, 12.8 and 11.8 μmol·L^(–1), respectively.

Graphene oxide as a hole extraction layer loaded on BiVO_(4)photoanode for highly efficient photoelectrochemical water splitting

The tailor-made oxygen evolution catalysts(OECs)paired with photoanodes offer a path to promote water oxidation kinetics;however,the unsatisfied interface between OECs and photoanode sets a barrier for efficient charge transfer.Herein,a graphene oxide(GO)layer to promote the charge transfer from BiVO_(4)(BVO)to NiOOH OEC is reported.It is found that GO layer inserted between BVO and NiOOH can not only serve as hole extraction layer due to its hole storage capability,but also improve the stability.Finally,the rationally designed NiOOH/GO/BVO photoanode achieves a photocurrent density of 3.81 mA·cm^(-2)at 1.23 V(vs.reversible hydrogen electrode(RHE)),which is 3.85 times as high as that of bare BVO.This work opens up low-cost auxiliary materials for enhancing photoelectrochemical water splitting.

1-Methoxycarbony-β-carboline from Picrasma quassioides exerts anti-angiogenic properties in HUVECs in vitro and zebrafish embryos in vivo

Angiogenesis is a crucial process in the development of inflammatory diseases,including cancer,psoriasis and rheumatoid arthritis.Recently,several alkaloids from Picrasma quassioides had been screened for angiogenic activity in the zebrafish model,and the results indicated that 1-methoxycarbony-β-carboline(MCC) could effectively inhibit blood vessel formation.In this study,we further confirmed that MCC can inhibit,in a concentration-dependent manner,the viability,migration,invasion,and tube formation of human umbilical vein endothelial cells(HUVECs) in vitro,as well as the regenerative vascular outgrowth of zebrafish caudal fin in vivo.In the zebrafish xenograft assay,MCC inhibited the growth of tumor masses and the metastatic transplanted DU145 tumor cells.The proteome profile array of the MCC-treated HUVECs showed that MCC could down-regulate several angiogenesis-related self-secreted proteins,including ANG,EGF,b FGF,GRO,IGF-1,PLG and MMP-1.In addition,the expression of two key membrane receptor proteins in angiogenesis,TIE-2 and u PAR,were also down-regulated after MCC treatment.Taken together,these results shed light on the potential therapeutic application of MCC as a potent natural angiogenesis inhibitor via multiple molecular targets.

Dual-property blue and red emission carbon dots for Fe(Ⅲ)ions detection and cellular imaging

The excitation wavelength-dependent and-independent emissions are two crucial fluorescent properties of carbon dots(CDs).However,CDs reported till date exhibit only one of these properties,which limits their practical applications.Herein,dual-property carbon dots(DCDs)with both the excitation wavelength-dependent and-independent emissions were synthesized via a facile onestep solvothermal method using 4-(2-pyridylazo)-resorcinol as the carbon precursor.The multi-functional applications of the resulting DCDs were also evaluated.The asprepared DCDs exhibited not only excellent monodispersity,high photostability,and storage stability,but also low toxicity,good biocompatibility,and cellular bioimaging capability.In addition,the DCDs exhibited excitation-dependent emission photoluminescence under low excitation wavelengths.The DCDs exhibited good Fe3+detection by quenching the blue emission fluorescence and showed a relatively low Fe3+detection limit of 0.067 lmol·L-1 based on three times signal-to-noise criteria(R2=0.99).Furthermore,the DCDs showed excitation-independent emission at low excitation wavelengths and exhibited red emission at about 598 nm to avoid damage to the body.These results demonstrate the excellent bioimaging properties of the DCDs.Owing to their dual PL properties,the as-prepared DCDs exhibited multi-functional applications:Fe3+detection and A549 cell bioimaging.These results will be helpful in developing novel CDs for applications in various fields.

Hollow Fe_(2)O_(3)/Co_(3)O_(4)microcubes derived from metal-organic framework for enhanced sensing performance towards acetone

In this work,hollow Fe_(2)O_(3)/Co_(3)O_(4)microcubes have been successfully synthesized through a hydrothermal method followed by an annealing process using metal-organic framework of Prussian blue as a soft template.The morphologies,microstructures,surface area and element compositions have been carefully characterized by a series of techniques.Meanwhile,compared with that of pure Fe_(2)O_(3)and Co_(3)O_(4),the gas sensor based on the hollow microcubes exhibits enhanced sensing performances towards acetone,e.g.,a higher response of 21.2 and a shorter response time of 5 s towards 20 ppm acetone at a relatively low working temperature of 200℃.Moreover,the hollow microcubes-based gas sensor still shows perfect long-term stability,excellent repeatability and the ability of sub-ppm level detection,which provides a possibility for its application in real life.The enhanced gas sensing performances can be attributed to the hollow structure with a high surface area and the formed p-n heterojunctions within the microcubes.

Modulating low-frequency tribocatalytic performance through defects in uni-doped and bi-doped SrTiO_(3)

Triboelectrification,a process that transforms mechanical energy into electrical energy through friction,holds promise for eco-friendly wastewater treatment.This study delves into the enhancement of tribocatalytic dye degradation using SrTiO_(3),a material notable for its non-piezoelectric and centrosymmetric properties.The synthesis of uni-and bi-doped SrTiOs particles,achieved through a solid-state reaction at 100℃,results in a high-purity cubic perovskite structure.Doping with rhodium(Rh)and carbon(C)causes crystal lattice contraction,internal stress,and significant oxygen vacancies.These changes notably improve tribocatalytic efficiency under solar irradiation,with Rh-doped SrTiO_(3) demonstrating an impressive degradation rate of approximately 88% for Rhodamine B(RhB),along with reaction rate constants near 0.9 h^(-1) at 554 nm and a noticeable blueshift.This study highlights that defects introduced by doping are integral to this process,boosting catalytic activity through energy state modification and enhancing surface redox radical production.Additionally,these defects are instrumental in generating a flexoelectric field,which markedly influences the separation of electron-hole pairs under solar irradiation.Our findings illuminate the complex interplay between material composition,defect states,and environmental conditions,paving the way for advanced strategies in environmental remediation through optimized tribocatalytic activity.