Drug-Primed Self-Assembly of Platinum-Single-Atom Nanozyme to Regulate Cellular Redox Homeostasis Against Cancer.

Single-atom nanozymes (SAzymes) with high catalytic activity exhibit the potential to disequilibrate the reactive oxygen metabolic balance in the tumor microenvironment (TME), which contains several endogenous reductive substances such as glutathione (GSH). Herein, a novel nano-assembly (CDs@Pt SAs/NCs@DOX) is first constructed using drug-primed platinum (Pt) single-atom or nanocluster nanozymes with a Pt loading of 34.8%, which exhibits prominent dual enzymatic activities to mimic peroxidase (POD) and glutathione oxidase (GSHOx). The unique GSHOx-like activity can efficiently scavenge GSH with a relatively low Km (1.04 mm) and high Vmax (7.46 × 10-6  m s-1 ), thus avoiding single oxygen (1 O2 ) depletion. CDs@Pt SAs/NCs@DOX simultaneously demonstrates low-temperature photothermal therapy and TME- or laser-controlled disassembly and drug release, which can effectively regulate cellular redox homeostasis and achieve high tumor growth inhibition. These outcomes may provide promising strategies for the preparation of Pt SAzymes with multiple activities and variable-sized nano-assemblies, allowing for broader applications of SAzymes and nano-assemblies in the biomedical field.

Robust solvatochromic carbon quantum dots for selective detection of water and Sn4+ and specific lipid imaging.

Developing carbon quantum dots (CQDs) with the solvatochromic effect and exploring multifunctional applications remains challenging. Herein, robust solvatochromic carbon quantum dots (RS-CQDs) with emission shift up to ∼62 nm from yellow to red was fabricated by the hydrothermal method. The RS-CQDs was used to detect water and Sn4+ in the linear ranges and limits of detection of 2.0-97.6% and 0.14% and 6.24-53.18 µM and 66.3 nM, respectively, and was further applied to determine Sn4+ in practical water samples with satisfactory results. In addition, RS-CQDs exhibited bright red emission in oil media with a 9.7-fold increase in fluorescence relative to aqueous media, making them a wash-free probe for specifically staining lipids. Compared to the commercial lipid marker BODIPY 493/503, the RS-CQDs-based probe has significant advantages, such as longer emission, larger Stokes shift, and better photostability, ensuring that RS-CQDs-based marker can implement real-time and wash-free monitoring and imaging of lipids in living cells, liver tissues, zebrafish embryos, and zebrafish larvae. This study provides a novel research direction for the development of metal-doped CQDs by demonstrating RS-CQDs as the viability of fluorescence probes for water and Sn4+ detection and the efficiency of RS-CQDs as a fluorescent marker for lipid imaging.

Nitrogen-doped carbon dots coupled with morin-Al3+: Cleverly design an integrated sensing platform for ratiometric optical dual-mode and smartphone-assisted visual detection of fluoride ion.

Ratiometric fluorescence sensor has high selectivity and good sensitivity; however, its development is limited by intricate design, tedious synthesis, etc. Herein, a facile and effective ratiometric fluorescence sensing platform for fluoride ion (F-) detection was developed by simply combining nitrogen-doped carbon dots (N-CDs) and morin-Al3+ based on inner filter effect (IFE). The competitive binding of F- to Al3+ obviously decreased morin-Al3+ fluorescence and increased N-CDs fluorescence, attributing to the inhibition of IFE between N-CDs and morin-Al3+. The as-constructed ratiometric fluorescence sensing platform can be used for F- detection with a wide linear range (0.5-150 µM) and a low detection limit (55.8 nM). Interestingly, with the introduction of F- into the N-CDs/morin-Al3+ sensing platform, a distinguishable change in fluorescence color from green to blue enabled the N-CDs/morin-Al3+ system to be used as a smartphone-assisted visual sensing platform for F- detection with a detection limit of 2.09 µM. This platform was successfully applied for the onsite monitoring of F- in various water samples with satisfying results. These findings provide a novel guidance for the facile construction of a ratiometric optical dual-mode and smartphone-assisted sensing platform based on CDs, revealing the broad application prospect of CDs in environmental monitoring field.

Intelligently design primary aromatic amines derived carbon dots for optical dual-mode and smartphone imaging detection of nitrite based on specific diazo coupling.

Primary aromatic amines derived carbon dots (PAA-CDs) with the protonated amino groups and high quantum yield of 46% were favorably obtained by one-step solvothermal treatment of m-phenylenediamine (m-PDA) in acidic environment. The interaction between the PAA-CDs and nitrite (NO2-) was inherited the characteristic reaction of m-PDA (a primary aromatic amine) and NO2-, resulting in strong fluorescence quenching and obvious absorption variation of the PAA-CDs. Meanwhile, a chromogenic reaction of diazo coupling can cause significant color changes. Hence, the PAA-CDs were developed for an optical dual-mode and smartphone imaging sensor for NO2- detection in the range of 3.0 ~ 40.0 µM with high selectivity, good sensitivity, and excellent anti-interference capability. A limit of detection (LOD) of 0.024 µM and 0.16 µM was implemented by fluorometry and colorimetry, respectively. For smartphone imaging colorimetry, the LODs of 0.46 µM (visible color) and 0.99 µM (fluorescence color) were acquired. More importantly, the established sensor has been successfully applied for the dynamic detection of NO2- in various food samples with the satisfying results. A smartphone imaging colorimetry method based on the CDs was firstly proposed to visually and quantitatively detect NO2-, which will broaden the application range of the CDs in food safety inspection.

A fluorometric and colorimetric dual-readout nanoprobe based on Cl and N co-doped carbon quantum dots with large stokes shift for sequential detection of morin and zinc ion.

A novel visual nanoprobe was developed for the sequential detection of morin and zinc ion (Zn2+) based on Cl and N co-doped carbon quantum dots (ClNCQDs) via a fluorometric and colorimetric dual-readout mode. The yellow fluorescence ClNCQDs was synthesized by the one-step hydrothermal treatment of o-chlorobenzoic acid and p-phenylenediamine. The most distinctive property of the ClNCQDs is the large stokes shift (177 nm), which is significantly higher than other reported CQDs. The fluorescence of the ClNCQDs can be effectively quenched by morin based on the synergistic effect of IFE, electrostatic interaction, and dynamic quenching process, and recovered upon the addition of Zn2+ due to strong interaction between morin and Zn2+. The nanoprobe exhibited favorable selectivity and sensitivity toward morin and Zn2+ with detection limits of 0.09 µM and 0.17 µM, respectively. Simultaneously, the color of the ClNCQDs solution was changed (light-pink â†’ faint-yellow â†’ dark-yellow) along with the variation of the fluorescence signal of the ClNCQDs. This proposed nanoprobe was successfully applied for morin and Zn2+ analyses in actual samples and live cells with high accuracy. The results of this study demonstrate the great application prospects of the ClNCQDs for morin and Zn2+ detection in complex actual samples and biosystems.

Ratiometric fluorescent sensors for sequential on-off-on determination of riboflavin, Ag+ and l-cysteine based on NPCl-doped carbon quantum dots.

The fluorescent sensor, especially ratiometric fluorescent sensor, is one of the most important applications for CQDs, which is becoming a research hotspot. Herein, carbon quantum dots co-doped with nitrogen, phosphorus and chlorine (NPCl-CQDs) were synthesized by acid-base neutralization reaction exothermic carbonization method. The as-fabricated NPCl-CQDs could emit blue fluorescence and possess excellent fluorescence properties. Based on the FRET, multifunctional and ratiometric fluorescent sensors for "on-off-on" sequential determination of riboflavin, Ag+, and Cys with good selectivity and high sensitivity were established. The linear range of riboflavin, Ag+, and Cys are 0.50-10.18 µM and 15.89-27.76 µM, 0.66-1.46 mM and 1.50-4.20 mM, and 0.01-0.15 µM and 0.15-0.36 µM with the limit of detection of 3.50 nM, 26.38 µM, and 0.96 nM, respectively. Furthermore, the sensors were successfully used to determine riboflavin, Ag+, and Cys in tablets, river water, and human urine with the recoveries of 95.2-104.0%, 95.6-102.0%, and 94.8-106.4%, respectively. More importantly, the as-constructed "on-off-on" NPCl-CQDs-based ratiometric fluorescent sensors were applied for detecting riboflavin, Ag+, and Cys in HeLa cells with satisfying results. The finding of this study shows the feasibility and effectiveness of the NPCl-CQDs as the available ratiometric fluorescent sensors for the determination of riboflavin, Ag+, and Cys in real samples and living cells.

Nitrogen, sulfur, phosphorus, and chlorine co-doped carbon nanodots as an "off-on" fluorescent probe for sequential detection of curcumin and europium ion and luxuriant applications.

Nitrogen, sulfur, phosphorus, and chlorine co-doped carbon nanodots (NSPCl-CNDs) were fabricated by acid-base neutralization and exothermic carbonization of glucose. The obtained NSPCl-CNDs possess excellent fluorescence properties and good biocompatibility. Curcumin (Cur) can dramatically quench the fluorescence of NSPCl-CNDs based on a synergistic effect of electrostatic interaction, inner filter effect, and static quenching, so a "turn-off" fluorescent probe for Cur detection was constructed with linear ranges of 0.24-13.16 µM and 13.62-57.79 µM. The LOD and LOQ of this fluorescent probe for Cur are 8.71 nM and 29.03 nM, respectively. More importantly, the fluorescence of the NSPCl-CNDs-Cur system can be recovered by europium ion (Eu3+), so a "turn-on" fluorescent probe for Eu3+ determination was established. The linear range, LOD, and LOQ for the detection of Eu3+ were 2.36-32.91 µΜ, 73.29 nM, and 244.30 nM, respectively. The proposed fluorescence methods were successfully utilized for Cur and Eu3+ determination in real samples with recoveries in the range 95.64-104.13% and 97.06-98.70%, respectively. Furthermore, the qualitative analysis of Cur can be realized by reagent strips with satisfying results. Finally, the as-constructed "off-on" fluorescent probe was successfully used to sequentially analyze Cur and Eu3+ at the cellular level. This method is simple and easy to implement, manifesting that NSPCl-CNDs have potential application value in fluorescent probing, food and drug testing, environmental monitoring, and cellular labeling. Graphical abstract.

A Non-Synonymous Single Nucleotide Polymorphism in the HJURP Gene Associated with Susceptibility to Hepatocellular Carcinoma among Chinese.

OBJECTIVE: HJURP (Holliday Junction-Recognizing Protein) plays dual roles in DNA repair and in accurate chromosome segregation during mitosis. We examined whether the single nucleotide polymorphisms (SNPs) of HJURP were associated with the risk of occurrence of hepatocellular carcinoma (HCC) among chronic hepatitis B virus (HBV) carriers from well-known high-risk regions for HCC in China. METHODS: Twenty-four haplotype-tagging SNPs across HJURP were selected from HapMap data using the Haploview software. We genotyped these 24 SNPs using the using Sequenom's iPLEX assay in the Fusui population, consisting of 348 patients with HCC and 359 cancer-free controls, and further investigated the significantly associated SNP using the TaqMan assay in the Haimen population, consisting of 100 cases and 103 controls. The genetic associations with the risk of HCC were analyzed by logistic regression. RESULTS: We observed an increased occurrence of HCC consistently associated with A/C or C/C genotypes of the non-synonymous SNP rs3771333 compared with the A/A genotype in both the Fusui and Haimen populations, with a pooled odds ratio 1.82 (95% confidence interval, 1.33-2.49; P = 1.9 × 10-4). Case-only analysis further indicated that carriers of the at-risk C allele were younger than those carrying the A/A genotype (P = 0.0016). In addition, the expression levels of HJURP in C allele carriers were lower than that in A/A genotype carriers (P = 0.0078 and 0.0010, for mRNA and protein levels, respectively). CONCLUSION: Our findings suggest that rs3771333 in HJURP may play a role in mediating the susceptibility to HCC among Chinese.

Mitochondrial calcium uniporter protein MCU is involved in oxidative stress-induced cell death.

Mitochondrial calcium uniporter (MCU) is a conserved Ca(2+) transporter at mitochondrial in eukaryotic cells. However, the role of MCU protein in oxidative stress-induced cell death remains unclear. Here, we showed that ectopically expressed MCU is mitochondrial localized in both HeLa and primary cerebellar granule neurons (CGNs). Knockdown of endogenous MCU decreases mitochondrial Ca(2+) uptake following histamine stimulation and attenuates cell death induced by oxidative stress in both HeLa cells and CGNs. We also found MCU interacts with VDAC1 and mediates VDAC1 overexpression-induced cell death in CGNs. This finding demonstrates that MCU-VDAC1 complex regulates mitochondrial Ca(2+) uptake and oxidative stress-induced apoptosis, which might represent therapeutic targets for oxidative stress related diseases.

Generation of Calhm1 knockout mouse and characterization of calhm1 gene expression.

Alzheimer's disease (AD) is the most common neurodegenerative disease among elderly people worldwide. Several genes have been validated to be associated with AD, and calcium homeostasis modulator 1 (Calhm1) is the latest suspected one. To investigate the biological and pathological function of Calhm1 systematically, we generated a Calhm1 conventional knockout mouse. However, both the male and female of elderly Calhm1 knockout (KO) mice showed similar ability to their wild type littermates in spatial learning and memory retrieving. Surprisingly, we found that Calhm1 mRNA could not be detected in mouse brains at different ages, although it is expressed in the human brain tissues. We further found that CpG islands (CGIs) of both mouse and human Calhm1 were hypermethylated, whereas CGI of mouse Calhm2 was hypomethylated. In addition, transcriptional active marker H3K4Di occupied on promoters of human Calhm1 and mouse Calhm2 at a considerable level in brain tissues, while the occupancy of H3K4Di on promoter of mouse Calhm1 was rare. In sum, we found that mouse Calhm1 was of rare abundance in brain tissues. So it might not be suitable to utilize the knockout murine model to explore biological function of Calhm1 in the pathogenesis of AD.

Lysine methylation of FOXO3 regulates oxidative stress-induced neuronal cell death.

FOXO transcription factors have a critical role in oxidative stress-induced neuronal cell death. A variety of post-translational modifications of FOXO family proteins have been reported, including phosphorylation, acetylation, ubiqutination and recently arginine methylation. Here, we demonstrate that the methyltransferase Set9 methylates FOXO3 at lysine 270. Methylation of FOXO3 leads to the inhibition of its DNA-binding activity and transactivation. Accordingly, lysine methylation reduces oxidative stress-induced and FOXO3-mediated Bim expression and neuronal apoptosis in neurons. Collectively, these findings define a novel modification of FOXO3 and show that lysine methylation negatively regulates FOXO3-mediated transcription and neuronal apoptosis.

Ca(2+) release induced by cADP-ribose is mediated by FKBP12.6 proteins in mouse bladder smooth muscle.

We examined the role and molecular mechanism of cADPR action on Ca(2+) spark properties in mouse bladder smooth muscle. Dialysis of cADPR with patch pipettes increased frequency and amplitude of spontaneous transient out currents (STOCs) to 6.1+/-0.87 currents/min from 1.2+/-0.36 currents/min (control) and to 179.8+/-48.7pA from 36.4+/-22.6pA (control), respectively, in wildtype (WT) cells, and the effects of cADPR on STOCs were significantly blocked by JVT-591, a RYR2 stabilizer. In contrast, no significant changes were observed in FKBP12.6 null cells. Further studies indicated that Ca(2+) spark properties were altered by cADPR in WT but not FKBP12.6 null cells, namely, Ca(2+) spark frequency was increased by about 3.4-fold, peak Ca(2+) (F/F0) increased to 1.72+/-0.57 from 1.56+/-0.13, size increased to 2.86+/-0.26 microM from 1.92+/-0.14 microM, rise time and half-time decay were prolonged 1.6-fold and 2.3-fold, respectively, in WT cells. Furthermore, in the presence of thapsigargin cADPR still altered Ca(2+) spark properties, and cADPR increased F/F0 without affecting Ca(2+) spark decay time in voltage clamping cells. Dissociation studies demonstrated that application of cADPR resulted in significant removal of FKBP12.6 proteins from sarcoplasmic reticulum (SR) microsomes, and that treatment of the RyR2 immunoprecipitation complexes with cADPR or FK506 disrupted the interaction between RyR2 and FKBP12.6. Finally, cADPR altered SR Ca(2+) load in WT myocytes but not in FKBP12.6-null myocytes. Taken together, these results suggest that Ca(2+) release induced by cADPR is mediated by FKBP12.6 proteins in mouse bladder smooth muscle.