Latest ArticlesIntracellular pH homeostasis is foundation of maintaining normal physiological functions. More and more evidences show that intracellular pH fluctuations were usually associated with many diseases (such as cancer, epilepsy and neurodegenerative diseases). It is very important to develop in situ real-time determination of pH. In recent years, it has been verified that pH can regulate the isomerization process of spiropyran. Thus, we report a pH fluorescent probe BSL, which is a closed loop spiropyran structure by coupling benzothiazole derivatives with indole salts. We utilizes the process of spiropyran isomerization as the trigger of excited state intramolecular proton transfer (ESIPT) effect, and adjust the process of spiropyran isomerization through pH, and then the molecular transformation from enol to ketone (enol: 525 nm, ketone: 677 nm) through the ESIPT effect. This process achieved accurate measurement of pH. The probe BSL showed sensitive and reversible fluorescence response to pH in vitro. Ultimately, BSL was successfully applied to detect pH fluctuations in cell oxidative stress model.
Point-of-care testing (POCT) technology is highly desirable for clinical diagnosis, healthcare monitoring, food safety inspection, and environment surveillance, because it enables rapid detection anywhere, anytime, and by anyone. Electrochemiluminescence (ECL) has been widely used in chemo-/bio analysis due to its advantages such as high sensitivity, simplicity, rapidity and easy to control, and is now attracting increasing attention for POCT applications. However, to realize the accurate on-site quantitation, it is still challenging to develop portable devices which can precisely collect, analyze, transmit and display the ECL signals. This review will focus on how to develop a portable ECL device by summarizing recent examples and analyzing their key components part by part. Then the possible solutions to the existing challenges in the development and applications of portable ECL devices are summarized and discussed in detail, followed by offering future perspectives. We attempted to provide an appealing viewpoint to inspire interested researchers to comprehend and explore portable ECL sensing systems for practical applications and even commercialization.
In recent years, Fe3O4 nanomaterials have received much attention in analytical chemistry due to their excellent magnetic and peroxidase-like activity. As the catalytic characteristics of Fe3O4 nanomaterials is similar to those of horseradish peroxidase (HRP), Fe3O4 nanomaterials are also used as peroxidase mimics and have achieved a certain development in many fields based on latest research results. To improve the stability and catalytic ability of simple Fe3O4 nanomaterials, various modification strategies of Fe3O4 nanomaterials have been developed. The recent advances of these strategies have been presented and discussed. In addition, this paper introduces the application of Fe3O4 nanozymes in the detection of food and industrial pollutants, as well as in the field of biosafety.
A novel photoredox-neutral ring-opening pyridylation of non-prefunctionalized cyclic oximes has been accomplished through phosphoranyl radical-mediated NO/CC bond cleavages followed by radical-radical coupling. This mild acid-, base-, and oxidant-free protocol provides highly site-selective and efficient access to distally pyridylated alkylnitriles, which could be scale-up synthesized and readily converted into skeletally diverse compounds. Notably, the oxidized ground-state photocatalyst generated via the SET oxidation of the highly reducing excited-state photocatalyst by cyanopyridines might initiate the following phosphoranyl radical-mediated deoxygenative process.
Vascularization and bone regeneration are closely related in the process of bone remodeling, and designing a bioactive scaffold with pro-angiogenic and osteogenic properties may accelerate the repair of bone defects. In this work, an iron-based metal–organic framework (MIL-88) was developed as a carrier for loading a pro-angiogenic small molecular drug (dimethyloxallyl glycine, DMOG), and then embedded into the PLGA nanofibrous scaffolds to repair cranial defects in rats. Imaging and histological evaluation indicated that PLGA/MIL@D scaffold markedly enhanced vascularization and bone regeneration in vivo. Moreover, in vitro assay showed that co-delivery system significantly promoted angiogenesis by stimulating endothelial cell migration, tube formation, and enhanced osteogenesis by promoting expression of osteoblast related proteins. In addition, PLGA/MIL@D scaffold promotes angiogenesis by activating the hypoxia-inducible factor-1 (HIF-1)/vascular endothelial growth factor (VEGF) signaling pathway. Altogether, this bioactive PLGA/MIL@D scaffold can combine angiogenesis with osteogenesis, and will be a bright strategy for the repair of bone defects.
Poor tumor accumulation remains a serious challenge for nanomedicines to achieve ideal antitumor outcomes. The different size preferences for systematic circulation, tumor retention and deep permeation have attracted great attention when designing antineoplastic nano-delivery system. Herein, we developed a nano-system which can shrink its size in tumor microenvironment to achieve better tumor retention and penetration. In this work, the cationic bovine serum albumin-protected, doxorubicin-loaded gold nanoclusters (CAuNC-DOX) and amino-functionalized mesoporous silica nanoparticles (MSN) are connected by Fe2+ and are further coated with hyaluronic acid (HA) to obtain a core-satellite MSN-Fe-CAuNC-DOX@HA nano system (MFADH). When reaching the tumor site, the HA shell, which endows the system with both good biocompatibility and preferable tumor targeting ability, was disintegrated, followed by acid-stimulated release of small-sized pharmacological unit—CAuNC-DOX for further tumor penetration. As demonstrated in both in vitro and in vivo results, MFADH showed excellent antitumor effect, providing a proof of concept for the feasibility of shrinkable nanoplatforms in tumor treatment.
Crohn's disease (CD) as a big issue to public health needs an accurate diagnosis urgently that is the common challenge among internal diseases. Herein, we design a mesoporous polydopamine with built-in metal-organic frameworks (dubbed MMP-b-MOFs) to combine with high-throughput mass spectrometry to extract serum peptide fingerprints from CD and healthy controls (HC). Benefitting by the size-exclusion and strong hydrophilicity of MMP-b-MOFs, the extracted peptide fingerprints present extremely high quality. CD and HC are explicitly discriminated with orthogonal partial least squares discriminant analysis (OPLS-DA), the corresponding area under the curve (AUC) value is 1.000. Moreover, eight peptides with clear identity are screened out and achieve the accurate diagnosis and subtype classification of CD, with all AUC values up to 1.000. Moreover, the unsupervised model is also established to precisely classify HC and CD based on these eight clearly identified peptides. This work brings great benefits for clinical detection especially internal medicine.
Herein, we report the first atroposelective C(sp2)–H bond acyloxylation enabled by a phosphine oxide directing group. Uniquely, this transformation is shown to proceed through an eight-membered palladacycle intermediate, as opposed to the kinetically and thermodynamically favored five-membered palladacycle intermediate. Additionally, L-pGlu-OH, a cheap and abundant chiral amino acid derivative, was identified as the best chiral ligand to promote this atroposelective remote CH functionalization reaction.
Highly active and durable oxygen reduction reaction (ORR) catalysts with sufficient activity and stability of Pt are beneficial for the commercialization of proton exchange membrane fuel cells. Here we report an effective approach to prepare a composite catalyst comprising of ordered L12-Pt3Fe intermetallic nanoparticles interact with single atom Fe-Nx-Cy active sites. The addition of Fe and the confinement effect of hierarchical porous structure limit the growth of intermetallic particle size (around 2.5 nm). The ligand effect of the electron transfer from Fe to Pt and the synergistic interaction between L12-Pt3Fe and Fe-Nx-Cy work together to reduce oxygen intermediates adsorption and improve kinetics process. Experimentally, the L12-Pt3Fe/CFe-N-C catalyst shows high mass activity and specific activity at 1.010 A/mgPt and 1.166 mA/cm2, respectively, which are 5.8 and 5.1 times higher than those of commercial Pt/C (0.174 A/mgPt and 0.230 mA/cm2). Thanks to the more stable L12 structure, L12-Pt3Fe/CFe-N-C exhibits better durability (14 mV E1/2 loss of L12-Pt3Fe/CFe-N-C and 33 mV E1/2 loss of commercial Pt/C) after 30,000 cycles accelerated stress tests. The strategy to design and prepare small particle Pt-based intermetallic alloys coordinated with M-N-C active sites provides a new direction to obtain low-cost and easily prepared effective ORR catalysts.
Selenium (Se) is an essential mineral element for human and other animals, and has been proved to improve plant growth and development and tolerance to different abiotic stresses. Selenium biofortification is considered to be a key strategy to increase the selenium content of edible parts of crops, which is helpful for improving human health. In this work, foliar fertilization with different concentrations and selenium forms was carried out on two wheat varieties at the flowering stage to compare the selenium enrichment effect of Na2SeO3, methylselenized selenocysteine (MSC), methylselenized glucose (MSG) and methylselenized lactide (MSL) in wheat grains. Surprisingly, MSG was found to be the preferable fertilizer. After the application of MSG, the highest selenium content in wheat gains reached 6 mg/kg in this experiment, and the average selenium content was 2–4 times versus that of Na2SeO3 application. Since MSG has high utilization rate and is easily available at relatively low cost, it can be employed as a potential selenium source for selenium biofortification to enhance the added value of agricultural industry.
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