Latest ArticlesRapid diagnosis of Salmonella is crucial for the effective control of food safety incidents, especially in regions with poor hygiene conditions. Polymerase chain reaction (PCR), as a promising tool for Salmonella detection, is facing a lack of simple and fast sensing methods that are compatible with field applications in resource-limited areas. In this work, we developed a sensing approach to identify PCR-amplified Salmonella genomic DNA with the naked eye in a snapshot. Based on the ratiometric fluorescence signals from SYBR Green Ⅰ and Hydroxyl naphthol blue, positive samples stood out from negative ones with a distinct color pattern under UV exposure. The proposed sensing scheme enabled highly specific identification of Salmonella with a detection limit at the single-copy level. Also, as a supplement to the intuitive naked-eye visualization results, numerical analysis of the colored images was available with a smartphone app to extract RGB values from colored images. This work provides a simple, rapid, and user-friendly solution for PCR identification, which promises great potential in molecular diagnosis of Salmonella and other pathogens in field.
Researchers have shown significant interest in modulating the peroxidase-like activity of nanozymes. Among these, bimetallic nanozymes have shown superior peroxidase-like activity over monometallic counterparts, offering enhanced performance and cost-efficiency in nanozyme designs. Herein, bimetallic nanozymes comprising nickel (Ni) and osmium (Os) incorporated into hyaluronate (HA) have been developed, resulting in HA-Nin/Os nanoclusters. Subsequently, comprehensive characterizations have been conducted. Further investigation has revealed that HA-Nin/Os efficiently catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation with hydrogen peroxide (H2O2), confirming its peroxidase-like behavior and role as a nanozyme. Impressively, HA-Ni2/Os (Ni/Os = 2:1) displays heightened substrate affinity, accelerated reaction rates, enhanced hydroxyl radical production in acidic conditions, and exhibits activity unit of 1224 U/mg, representing more than two-fold increase compared to non-Ni-supported Os nanozyme. Theoretical calculations indicate that Ni support enhances the peroxidase-like process of Os nanozyme by improving H2O2 adsorption and TMB oxidation. Crucially, the support of Ni does not significantly alter the other enzyme-like activities of Os nanozymes, thereby enabling Ni to selectively enhance their peroxidase-like activity. In terms of application, the peroxidase-like ability of HA-Ni2/Os, facilitated by HA's carboxyl groups enabling crosslinking, proves effective in a squamous carcinoma antigen immunoassay. Moreover, HA-Ni2/Os exhibit reliable stability, promising as a peroxidase substitute. This work underscores the advantages of incorporating Ni into Os, specifically enhancing peroxidase-like activity, highlighting the potential of Os bimetallic nanozymes for peroxidase-based applications.
A novel Fe-doping three-dimensional flower-like Bi7O9I3 microspheres with plasmonic Bi and rich surface oxygen vacancies (Fe-Bi/Bi7O9I3/OVs) was prepared as catalysts, and further coupled with natural air diffusion electrode (NADE) to construct the heterogeneous visible-light-driven photoelectro-Fenton (HE-VL-PEF) process to enhance the degradation and mineralization of tetracycline (TC). Interfacial ≡Fe sites, OVs and Bi metal were simultaneously constructed via Fe doping, which effectively improved visible light absorption and the separation efficiency of photogenerated carriers to further accelerate the transformation of Fe(Ⅲ) to Fe(Ⅱ), achieving Fenton reaction recycling. HE-VL-PEF process could achieve enhanced treatment of pollutants, thanks to the synergistic effect of electro-Fenton (EF) and photo-Fenton (PF). NADE exhibited excellent H2O2 electrosynthesis without external oxygen-pumping equipment. Under the irradiation of visible light, Fe-Bi/Bi7O9I3/OVs could achieve more photoelectrons to accelerate the transformation of Fe(Ⅲ) to Fe(Ⅱ) or directly activate H2O2. DFT calculations also clearly demonstrated that except for the fast charge separation and transfer, Fe-Bi/Bi7O9I3/OVs could achieve a faster electron transport between Fe-O, facilitating Fe site acquire more electron. Consequently, the Fe-Bi/Bi7O9I3/OVs in HE-VL-PEF process presented performance superiorities including excellent pollutant removal (91.91%), low electric energy consumption of 66.34 kWh/kg total organic carbon (TOC), excellent reusability and wide pH adaptability (3–9).
Compared with natural enzymes, nanozymes have the advantages of high stability and low cost; however, selectivity and sensitivity are key issues that prevent their further development. In this study, we report a cascade nanozymatic system with significantly improved selectivity and sensitivity that combines more substrate-specific reactions and sensitive fluorescence detection. Taking detection of ascorbic acid (AA) as an example, a cascade catalytic reaction system consisting of oxidase-like N-doped carbon nanocages (NC) and peroxidase-like copper oxide (CuO) improved the reaction selectivity in transforming the substrate into the target product by more than 1200 times against the interference of uric acid. The cascade catalytic reaction system was also applicable for transfer from open reactors into a spatially confined microfluidic device, increasing the slope of the calibration curves by approximately 1000-fold with a linear detection range of 2.5 nmol/L to 100 nmol/L and a low limit of detection of 0.77 nmol/L. This work offers a new strategy that achieves significant improvements in selectivity and sensitivity.
Two thioamino acids and four fluorinated amino acids were employed to substitute either partially or entirely the Ile2, Ser3, Ile6, and Ser7 residues of Leu10-teixobactin to prepare ten analogues and the bioactivity of them was investigated. The SAR studies revealed that Ile6 was tolerable for both thioamidation and fluoridation, while Ser7 was identified as the most tolerable site for thioamidation. Analogue 1a demonstrated comparable or slightly improved antibacterial activity, superior protease stability compared to Leu10-teixobactin, while not exhibiting obvious cytotoxicity against mammalian cells.
Glioma is the most common malignant tumor of the brain. The postoperative recurrence rate was high, and the 2-year survival rate only increased by 20%–25%. The reason is the blood-brain barrier (BBB). BBB is a physical barrier that stabilizes the physiological environment of brain tissue and protects the central nervous system from the invasion of harmful substances. Drug delivery based on nanotechnology and nanocarriers has attracted much attention due to its biological safety, continuous drug release time, increasing solubility, biological drug activity, and enhanced BBB permeability. By modifying different substances on the surface of nanocarriers, the BBB is bypassed by receptor-mediated and cell endocytosis and exocytosis. In addition, the purpose of bypassing BBB-targeted drug delivery can also be achieved by intranasal administration and local administration. This paper reviews different target transport mechanisms, mainly in invasive and non-invasive strategies, the nanocarriers that have made progress and the nanocarrier strategy of bypassing BBB are listed.
Developing BiVO4 photoanode with efficient carrier transfer and fast water oxidation kinetics is the permanent pursuit to achieve the state-of-art solar-driven photoelectrochemical (PEC) water splitting. The capacity to increase the PEC activity of BiVO4 by loading oxygen evolution co-catalysts (OECs) has been proven, however it suffers from sluggish charge carriers dynamics brought on by the complicated interface between BiVO4 and OECs as well as poor long-term durability. Herein, we connected OECs (NiFeOx) and photoanode with a Al-O bridge for bettering the PEC performance of BiVO4. The Al-O bridge served as a channel to extract hole from BiVO4 to NiFeOx, thus boosting charge carriers′ separation and preventing BiVO4 from photo-corrosion. The Al-O bridging photoanode (NiFeOx/Al2O3/BiVO4) demonstrated a high photocurrent density of 5.87 mA/cm2 at 1.23 V vs. RHE and long-term photostability in comparison to NiFeOx/BiVO4 photoanode. This study proposes a unique technique to boost charge carriers′ separation between BiVO4 and OECs for high-efficiency solar-driven PEC water splitting.
Wound healing in diabetic patients presents significant challenges due to heightened risks of bacterial infection, elevated glucose levels, and insufficient angiogenesis. Nanozymes are widely employed for wound healing, but most current nanozyme systems exhibit only moderate activity limited by incompatible reaction microenvironments including pH and hydrogen peroxide (H2O2) concentration. Herein, a glucose-activated nanozyme hydrogel was developed using bovine serum albumin (BSA)-modified gold nanoparticles (Au NPs) attached to a two-dimensional (2D) metal-organic framework (MOF) (Cu-TCPP(Fe)@Au@BSA) by an in situ growth method. The Au NPs function as a glucose oxidase (GOx)-like enzyme, converting glucose to gluconic acid and H2O2, triggering the peroxidase (POD)-like activity of Cu-TCPP(Fe) to produce hydroxyl radicals (•OH), effectively eliminating bacteria. Additionally, the modification of BSA reduces the Au NP size, enhancing enzyme activity. Both in vitro and in vivo tests demonstrate that this nanozyme hydrogel can be activated by the microenvironment to lower blood glucose, eliminate bacterial infections, and promote epithelial formation and collagen deposition, thus accelerating diabetic wound healing effectively. The multifunctional nanozyme hydrogel dressing developed in this study presents a promising therapeutic approach to enhance diabetic wound healing.
Black phosphorus (BP), as a rising star of 2D nanomaterials has drawn considerable attention in cancer therapy. However, the poor stability under ambient conditions limits their practical applications. Herein, a multiple supramolecular assembly composed of adamantane-modified hyaluronic acid (HAADA), ferrocene-modified cinnamaldehyde (Fc-CA), guanidinium-functionalized β-cyclodextrin (Guano-CD), and black phosphorus (BP) nanosheets was successfully fabricated through cooperative host-guest and electrostatic interactions. Owing to the cooperative contribution of these building blocks, the obtained supramolecular assembly simultaneously possesses multiple functions including excellent stability, good biocompatibility and targeting property, and a high inhibition effect toward cancer cells. We believe that this work might provide new insights into designing a new generation of cancer theranostic protocols for potential clinical applications.
The fabrication of bioreceptor-free method for accurate and sensitive detection of ochratoxin A (OTA) in cereal is critical, but still a significant challenge to mitigate risks to food industries and public health. In this study, a smartphone-ratiometric fluorescence sensor for the ultrasensitive detection of OTA is developed based on a porphyrinic metal-organic framework and silica nanoparticle composite (Zr-MOF/SiNPs) away from the use of antibodies and aptamers. Due to the excellent recognition ability of Zr-MOF and good storage stability of SiNPs, OTA is detected by Zr-MOF/SiNPs with a wide linear range of 0.05–1000 ng/mL and low detection limit of 0.016 ng/mL. Moreover, the red–blue ratio values of the fluorescence images are extracted through the smartphone color recognizer application with a limit of detection of 1.74 ng/mL, lower than the permissible content of OTA in cereal prescribed by World Health Organization. This sensing platform has been successfully applied in maize samples with superior repeatability and satisfactory recoveries, providing a novel way for simple and label-free analysis of OTA in cereal.
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