Latest ArticlesElevated level of hypochlorous acid (HClO) is closely associated with cancer development. Identifying HClO level in cancer cells would provide important evidence in either early-stage cancer diagnostics or monitoring of its treatment efficiency. In this work, a new pyronine-based fluorescent probe for rapid and sensitive detection of HClO was developed by condensing meso–formyl pyronine (PyCHO) with 2-hydrazinopyridine to form meso–pyridylhydrazone-functionalized pyronine PyHP, PyHP is nonfluorescent due to the excited-state C=N isomerization nonradiative decay, whereas the HClO-triggered formation of meso–triazolopyridyl pyronine PyTP abolishes the C=N isomerization and thus greatly enhances the fluorescence. With the probe, the cancer cells/tumor were distinguished with high-contrast from normal ones by laser confocal fluorescence imaging, and the tumor-to-normal (T/N) ratios obtained exceed the clinically acceptable threshold of 2.0. Moreover, its capability of in vivo imaging tumor was also demonstrated. These results indicate the potential of PyHP as an effective tool in the early clinical diagnosis of cancers.
Carbon dots (CDs) with precise targeting function show great potential in the field of drug delivery therapeutics. In this study, the functionalized nucleus-targeting orange-emissive CDs with nuclear localization sequence (NLS) were loaded with adriamycin (DOX) to obtain a nucleus-targeting orange-emissive CDs drug delivery system (CDs-NLS-DOX), which delivered DOX to tumor cell nuclei to enhance its anti-tumor activity. The drug carrier orange-emissive CDs showed excitation-independent behavior, stable and enhanced imaging capability and good biocompatibility in vitro and in vivo. Meanwhile, the CDs-NLS could target the nuclei efficiently, and the CDs-NLS-DOX complexes had a high drug loading rate (59.4%) after loading DOX, exhibiting pH-dependent DOX release behavior through breaking acylhydrazone bond in a weak acidic environment. In addition, the CDs-NLS-DOX complexes exhibited an enhanced killing activity against human hepatoma cells (HepG2). The in vivo therapeutic effects on HepG2 nude mice transplanted tumors indicated the CDs-NLS-DOX had a stronger ability to inhibit tumor growth compared to free DOX. In short, CDs-NLS-DOX is expected to be a precise and efficient nucleus-targeting nano-drug delivery system for tumor treatment.
Local delivery of nanoparticles holds promise for colorectal cancer (CRC) therapy. However, the presence of the mucus layer on the epithelium poses a significant challenge to drug delivery, thereby adversely affecting treatment efficiency. It is crucial to develop efficient drug delivery carriers that can effectively overcome mucus barriers to treat colorectal cancer. Herein, we utilized poly(1,4-butadiene)-b-poly(ethylene oxide) polymers to prepare four distinct geometries of polymeric micelles, namely linear micelles (LMs), worm-like micelles (WLMs), large spherical micelles (LSMs), and small spherical micelles (SSMs) to investigate the influence of shape effects on overcoming colonic mucosal barrier. We found that the carriers exhibited diverse shapes while maintaining comparable physicochemical properties. Of these, WLMs had an aspect ratio similar to segmented filamentous bacteria, which exhibited superior mucus penetration ability, leading to prolonged drug release kinetics and faster entry into epithelial cells compared to LSMs. Furthermore, rectally administrated 10-hydroxycamptothecin-loaded WLMs traversed the colorectal mucus in orthotopic CRC nude mice model, penetrated and accumulated within tumor tissue, and effectively aggregated within cancer cells, thereby inducing significantly robust antitumor outcomes in vivo. These findings underscore the significance of shape design in overcoming colonic mucosal absorption barriers, offering a novel approach for the development of drug delivery carriers tailored for effective tumor therapy.
As a type of new carbon-based nanomaterials, carbon dots (CDs) possess exceptional optical properties, making them highly desirable for use in fluorescent sensors. However, the CDs with deep-red (DR) or near-infrared (NIR) emission have rarely been reported. In this work, we prepared deep-red emissive fluorine-doped carbon quantum dots (F-CDs) by introducing a precursor simultaneously containing fluorine and amidogen. The synergistic effect of nitrogen doping and D-π-A pattern production contributed to the maximum emission of F-CDs at 636 nm with an absolute quantum yield of 36.00% ± 0.68%. Moreover, we designed an F-CDs-based fluorescence assay to determine the content of hypochlorite (ClO−), with a limit of detection (LOD) as low as 15.4 nmol/L, indicating the high sensitivity of F-CDs to ClO−. In real samples, the F-CDs-based fluorescent sensor exhibited excellent sensitivity and selectivity in the detection of ClO−, with an error below 2%, suggesting their great potential in daily life. In cancer cell imaging, the F-CDs not only demonstrated high sensitivity to ClO− but also exhibited excellent mitochondria targeting, as evidenced by the high Pearson's correlation coefficient (PCC) of 0.93 in colocalization analysis. The work presented here suggests the great potential of replacing commercial dyes with F-CDs for highly specific mitochondria labeling and cell imaging.
The combination of horseradish peroxidase (HRP) and a fluorescence substrate has been attracting great interests in developing sensitive biochemical analysis and immunoassays. 10-Acetyl-3,7-dihydroxyphenoxazine (ADHP or Amplex red) is the most sensitive fluorogenic substrate known for HRP in current market, however, it suffers from some drawbacks, such as non-specific reactivity to carboxylesterase and limited fluorescence stability. In the present study, a novel HRP substrate 10-cyclopropylcarbonyl-dichloro-dihydroxyphenoxazine (AR-2), has been prepared, which exhibited improved sensitivity than ADHP in sensing HRP. Moreover, the fluorescence of AR-2/HRP demonstrated improved tolerance to physiological relevant pH fluctuation as compared to ADHP/HRP. Successful detection of uric acid/urate oxidase reaction indicated excellent application prospect of AR-2/HRP for monitoring H2O2-generating biochemical reactions. More interestingly, an enzyme-linked immunosorbent assay (ELISA) using AR-2 as the fluorescence reporter has been successfully used in detecting IgG against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from human serum samples. Overall, AR-2 exhibits improved performances over the commercial ADHP, which will be an ideal alternative to ADHP in HRP-based fluorescence biochemical analysis and immunoassays.
Introducing heavy halogen atoms into organic small molecules is a practical strategy for efficient singlet oxygen (1O2) generation. Generally, bromine or iodine atoms are introduced on the aza-boron-dipyrromethene (aza-BODIPY) core, rather than on the periphery aryl rings for efficient 1O2 generation. Herein, an aza-BODIPY dye NBDPBr with unexpected bromination on the periphery aryl rings was synthesized for photoacoustic (PA) imaging-guided synergistic photothermal therapy (PTT) and photodynamic therapy (PDT) in tumor cells. Owing to unexcepted bromination at the periphery aryl rings, NBDPBr demonstrated an outstanding singlet oxygen quantum yield of 66% which was superior to similar brominated photosensitizers previously reported. After encapsulation with amphiphilic polymer F-127, hydrophilic NBDPBr nanoparticles (NPs) were fabricated and exhibited an excellent photothermal conversion efficiency (η) of 43.0% under 660 nm photoirradiation. In vivo PA imaging results demonstrated that NBDPBr NPs could specifically accumulate at tumor sites and realized the maximum tumor retention at 7 h post-injection. All the in vitro and in vivo results indicated the significant potence of NBDPBr with unexpected bis-bromination for PA imaging-guided synergetic PDT/PTT.
C-Oligosaccharides are rare in nature and possess diverse bioactivities. However, their chemical synthesis faces many challenges. In this work, enzymatic introduction of C-linked sugar chains to target aglycones was successfully achieved by multi-enzymatic cascade reactions. A C-glycosyltransferase from Aloe barbadensis was employed to introduce the first C-linked glucose and then a cyclomaltodextrin glucanotransferase from Bacillus licheniformis was used to extend the sugar chain. A total of twenty C-oligosaccharides with 2–6 sugars were synthesized from scale-up reactions and exhibited good water solubility and sodium-dependent glucose transporter 2 (SGLT2) inhibitory activity. Furthermore, a glucoamylase was used to control the length of the sugar chain and the C-maltosides were efficiently synthesized. These findings not only expanded the structural diversity of C-oligosaccharides, but also provided a strategy for the modification of C-glycoside drugs to improve the druggability.
Heterogeneous reaction of mineral aerosols and atmospheric polluting gases play an important role in atmospheric chemistry. In this study, the reactions of NO2 with or without SO2 mixture gas on the surface of α-Fe2O3 particles under dry conditions were studied. The effects of sodium dodecyl sulfate (SDS) and the heterogeneous reaction under both dark and UV irradiation conditions were investigated. The infrared spectrum analyzed by the two-dimensional correlation spectroscopy (2D-COS) was used to obtain the products formation sequences. The results showed that UV irradiation can promote the production of nitrate. The 2D-COS analysis indicated SDS changed the sequence order of nitrate and nitrite species during reactions. In oxidation conditions, the final product of heterogeneous reaction of NO2 and α-Fe2O3 was monodentate nitrate. Only the heterogenous reaction of NO2 and α-Fe2O3 containing SDS (FOS) without UV light, the final product was bidentate nitrate. SDS was the catalysis agent supply and photoresist to the system. With surface active compounds, the environmental lifetime of heterogeneous reactions between trace gases and aerosols extends. Surfactants, ultraviolet light, and the types of gases involved in the reaction all have complex effects on the aerosol aging process. This study provided a reference for subsequent heterogeneous reaction studies and the formation of aerosols.
Exploring the therapeutic effect of single atom catalysts beyond reactive oxygen species (ROS) modulation would boost the prosperity of nanomedicine in cancer treatment. Autophagy as a vital therapy target offers new options for the control of renal cell carcinoma (RCC) progression. Herein, Fe single atom-decorated graphene oxide (Fe1-GO) nanosheet is developed to be a feasible autophagy inducer in RCC treatment. With the well-dispersed O−Fe1−O active sites, Fe1-GO kills ACHN cells effectively but maintains acceptable cytotoxicity to the normal podocyte and HK2 ones. In-depth analyses ascribe the inhibition of ACHN cells to the upregulated autophagy instead of the commonly known catalytic ROS generation. The in vivo therapeutic effect of Fe1-GO nanomedicine is also validated by the RCC-bearing BALB/c mice model, realizing an 89% reduction of tumor weight and good biosafety. This work provides new insights into the design of autophagy regulators as well as potential therapeutic strategies for RCC treatment.
With the deep integration of electrochemical research with energy, environment, catalysis, and other fields, more and more new electrochemical catalytic reactions have entered our research field. Alloy catalysts have recently emerged as a new type of nanomaterial due to the rapid development of kinetic controlled synthesis technology. These materials offer several advantages over monometallic catalysts, including larger element combinations, complex geometries, bifunctional sites, and reduced use of precious metals. This paper provides a review of alloy electrocatalysts that are designed and prepared specifically for electrocatalytic applications. The use of alloy materials in electrocatalyst design is also discussed, highlighting their widespread application in this field. First, various synthesis methods and synthesis mechanisms are systematically summarized. Following that, by correlating the properties of materials with the structure, relevant strategies toward advanced alloy electrocatalysts including composition regulation, size, morphology, surface engineering, defect engineering, interface engineering and strain engineering are classified. In addition, the important electrocatalytic applications and mechanisms of alloy electrocatalysts are described and summarized. Finally, the current challenges and prospects regarding the development of alloy nanomaterials are proposed. This review serves as a springboard from a fundamental understanding of alloy structural dynamics to design and various applications of electrocatalysts, particularly in energy and environmental sustainability.
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