Molecular insights into the catalytic mechanism of a phthalate ester hydrolase.

Phthalate esters (PAEs) are emerging hazardous and toxic chemicals that are extensively used as plasticizers or additives. Diethyl phthalate (DEP) and dimethyl phthalate (DMP), two kinds of PAEs, have been listed as the priority pollutants by many countries. PAE hydrolases are the most effective enzymes in PAE degradation, among which family IV esterases are predominate. However, only a few PAE hydrolases have been characterized, and as far as we know, no crystal structure of any PAE hydrolases of the family IV esterases is available to date. HylD1 is a PAE hydrolase of the family IV esterases, which can degrade DMP and DEP. Here, the recombinant HylD1 was characterized. HylD1 maintained a dimer in solution, and functioned under a relatively wide pH range. The crystal structures of HylD1 and its complex with monoethyl phthalate were solved. Residues involved in substrate binding were identified. The catalytic mechanism of HylD1 mediated by the catalytic triad Ser140-Asp231-His261 was further proposed. The hylD1 gene is widely distributed in different environments, suggesting its important role in PAEs degradation. This study provides a better understanding of PAEs hydrolysis, and lays out favorable bases for the rational design of highly-efficient PAEs degradation enzymes for industrial applications in future.

Construction of a Spatial-Confined Self-Stacking Catalytic Circuit for Rapid and Sensitive Imaging of Piwi-Interacting RNA in Living Cells.

Piwi-interacting RNAs (piRNAs) are small noncoding RNAs that repress transposable elements to maintain genome integrity. The canonical catalytic hairpin assembly (CHA) circuit relies on random collisions of free-diffused reactant probes, which substantially slow down reaction efficiency and kinetics. Herein, we demonstrate the construction of a spatial-confined self-stacking catalytic circuit for rapid and sensitive imaging of piRNA in living cells based on intramolecular and intermolecular hybridization-accelerated CHA. We rationally design a 3WJ probe that not only accelerates the reaction kinetics by increasing the local concentration of reactant probes but also eliminates background signal leakage caused by cross-entanglement of preassembled probes. This strategy achieves high sensitivity and good specificity with shortened assay time. It can quantify intracellular piRNA expression at a single-cell level, discriminate piRNA expression in tissues of breast cancer patients and healthy persons, and in situ image piRNA in living cells, offering a new approach for early diagnosis and postoperative monitoring.

Measurable residual disease testing by next generation sequencing is more accurate compared with multiparameter flow cytometry in adults with B-cell acute lymphoblastic leukemia.

Results of measurable residual disease (MRD)-testing by next-generation sequencing (NGS) correlate with relapse risk in adults with B-cell acute lymphoblastic leukemia (ALL) receiving chemotherapy or an allotransplant from a human leukocyte antigen (HLA)-identical relative or HLA-matched unrelated donor. We studied cumulative incidence of relapse (CIR) and survival prediction accuracy using a NGS-based MRD-assay targeting immunoglobulin genes after 2 courses of consolidation chemotherapy cycles in 93 adults with B-cell ALL most receiving HLA-haplotype-matched related transplants. Prediction accuracy was compared with MRD-testing using multi-parameter flow cytometry (MPFC). NGS-based MRD-testing detected residual leukemia in 28 of 65 subjects with a negative MPFC-based MRD-test. In Cox regression multi-variable analyses subjects with a positive NGS-based MRD-test had a higher 3-year CIR (Hazard Ratio [HR] = 3.37; 95 % Confidence Interval [CI], 1.34-8.5; P = 0.01) and worse survival (HR = 4.87 [1.53-15.53]; P = 0.007). Some data suggest a lower CIR and better survival in NGS-MRD-test-positive transplant recipients but allocation to transplant was not random. Our data indicate MRD-testing by NGS is more accurate compared with testing by MPFC in adults with B-cell ALL in predicting CIR and survival. (Registered in the Beijing Municipal Health Bureau Registration N 2007-1007 and in the Chinese Clinical Trial Registry [ChiCTR-OCH-10000940 and ChiCTROPC-14005546]).

Comparison of Objective Visual Quality Following SMILE and SmartPulse Technology-Assisted TransPRK at a 1,050-Hz Ablation Frequency for Moderate-to-High Myopia.

PURPOSE: To compare the objective visual quality of moderate-to-high myopia corrected by small incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (TransPRK) at a 1,050-Hz ablation frequency, assisted by Smart-Pulse technology (SCHWIND eye-tech-solutions). METHODS: This study involved 123 patients (123 eyes) with moderate-to-high myopia between July 2020 and January 2021. They were categorized into the SMILE group (67 patients, 67 eyes) and the TransPRK group (56 patients, 56 eyes). Follow-ups were conducted at 6 months postoperatively to record the logarithm of the minimum angle of resolution visual acuity, and the Strehl ratio and higher order aberrations were measured using the Sirius anterior segment analysis device (SCHWIND eye-tech-solutions) under a 6-mm pupil diameter at various postoperative intervals. RESULTS: At 1 week and 1 month postoperatively, the uncorrected distance visual acuity (UDVA) in the SMILE group was superior to that in the TransPRK group (P < .05 for both). At 1 week and 1 month postoperatively, the Strehl ratio value in the SMILE group was higher than that in the TransPRK group (P < .05 for both). At 1, 3, and 6 months postoperatively, coma was greater in the SMILE group than in the TransPRK group (P < .05 for all). Spherical aberrations were lower in the SMILE group than in the TransPRK group at 3 and 6 months postoperatively (P < .05). At 6 months postoperatively, UDVA was -0.09 ± 0.08 and -0.11 ± 0.05 logMAR in the SMILE and TransPRK groups, respectively, which exceeded their preoperative corrected distance visual acuity of -0.05 ± 0.04 and -0.09 ± 0.08 logMAR (all P < .001). Compared with preoperative values, the Strehl ratio, total higher order, coma, and spherical aberration differences were significantly increased postoperatively in both groups (all P < .001). CONCLUSIONS: Both surgical methods improved UDVA and each had its advantages. The visual quality of SMILE was superior at 1 week and 1 month postoperatively (Strehl ratio values were higher than those of the TransPRK group), and its spherical aberration was lower than that of the TransPRK group at 3 and 6 months; TransPRK with SmartPulse technology with a 1,050-Hz ablation frequency showed that coma was significantly lower than that of the SMILE group at 1, 3, and 6 months postoperatively. [J Refract Surg. 2024;40(7):e490-e498.].

Development of a DNAzyme-Driven Fluorescent Light-Up Aptasensor for Label-Free Detection of Multiple lncRNAs.

Long noncoding RNAs (lncRNAs) act as the dynamic regulatory molecules that control the expression of genes and affect numerous biological processes, and their dysregulation is associated with tumor progression. Herein, we develop a fluorescent light-up aptasensor to simultaneously measure multiple lncRNAs in living cells and breast tissue samples based on the DNAzyme-mediated cleavage reaction and transcription-driven synthesis of light-up aptamers. When target lncRNAs are present, they can be recognized by template probes to form the active DNAzyme structures, initiating the T4 PNK-catalyzed dephosphorylation-triggered extension reaction to generate double-strand DNAs with the T7 promoter sequences. The corresponding T7 promoters can initiate the transcription amplification catalyzed by the T7 RNA polymerase to generate abundant Broccoli aptamers and malachite green aptamers, which can bind DFHBI-1T and MG to generate strong fluorescence signals. Taking advantage of the good selectivity of DNAzyme-mediated cleavage of lncRNAs, high amplification efficiency of T7 transcription-driven amplification reaction, and bright fluorescence of the RNA aptamer-fluorophore complex, this method exhibits high sensitivity with a detection limit of 21.4 aM for lncRNA HOTAIR and 18.47 aM for lncRNA MALAT1, and it can accurately measure multiple lncRNAs in both tumor cell lines and breast tissue samples, providing a powerful paradigm for biomedical research and early clinic diagnostics.

Dietary effects of vitamin C on antioxidant capacity, intestinal microbiota and the resistance of pathogenic bacteria in cultured Silver pomfret (Pampus argenteus).

As most teleosts are unable to synthesize vitamin C, supplemental diets containing vitamin C diets play a crucial role in fish health. The aim of this study was to investigate the effect of dietary vitamin C on the intestinal enzyme activity and intestinal microbiota of silver pomfre (Pampus argenteus). Four experimental diets were supplemented with basic diets containing 300 mg of vitamin C/kg (group tjl3), 600 mg of vitamin C/kg (group tjl6), and 1200 mg of vitamin C/kg (group tjl12), as well as vitamin C-free supplemental basic diet (group tjl0), respectively. The four diets were fed to juvenile P. argenteus (average initial weight: 4.68 ± 0.93 g) for 6 weeks. The results showed that the activity of SOD (superoxide dismutase) and CAT (catalase) increased significantly while that of MDA (malondialdehyde) decreased significantly in group tjl3 compared to vitamin group tjl0. At the genus level, groups tjl0, tjl6, and tjl12 contained the same dominant microbial community, Stenotrophomonas, Photobacterium, and Vibrio, whereas group tjl3 was dominated by Stenotrophomonas, Delftia, and Bacteroides. Among the fish fed with a basic diet containing 300 mg of vitamin C/kg, the intestines exhibited a notable abundance of probiotic bacteria, including lactic acid bacteria (Lactobacillus) and Bacillus. The abundance of Aeromonas in groups tjl3 and tjl6 was lower than that of the vitamin C-free supplemental basic diet group, whereas Aeromonas was not detected in group tjl12. In addition, a causative agent of the disease outbreak in cultured P. argenteus, Photobacterium damselae subsp. Damselae (PDD) was the dominant microbiota community in groups tjl0, tjl6 and tjl12, whereas the abundance of PDD in group tjl3 was the lowest among the diets. Taken together, the diets supplied with vitamin C could influence the composition microbial community of P. argenteus. The low level of vitamin C (300 mg of vitamin C/kg per basic diet) supplementation could not only improve the antioxidant capacity but also resist the invasion of pathogenic bacteria.

True lumen expansion but no aortic remodeling following thoracic endografting and distal bare-stent for subacute complicated Type B aortic dissection.

BACKGROUND: The effects of thoracic endovascular aneurysm repair (TEVAR) with additional distal bare metal stents (BMSs) in patients with subacute complicated type B aortic dissection (cTBAD) are unclear and are investigated in this retrospective study. METHODS: The medical records of 67 patients who received TEVAR due to subacute cTBAD were reviewed. Areas of true lumen (TL) and false lumen at 5 levels-- pulmonary artery (PA), diaphragm, renal artery (RA), middle of the infrarenal aorta, and aortic bifurcation-were measured using computed tomography before and 3, 6, and 12 months after surgery. The TL ratio (TL area/total aortic area) and total aortic area at each time point were compared between the TEVAR+BMS (n=37) and TEVAR-only (n=30) groups. The effects of BMS use and time were evaluated using generalized estimating equations and generalized linear regression models. RESULTS: Baseline characteristics, remodeling types, and clinical outcomes did not differ significantly between the 2 groups. Postoperative TL ratios at the diaphragm and RA were significantly higher in the TEVAR+BMS group than in the TEVAR-only group (p < 0.05). BMS use and time had significant interaction effects at the PA, diaphragm, and RA (all p < 0.05), but effects on total aortic area were not significant at any of the 5 parts. TL ratios at the diaphragm and RA exhibtied greater improvement in the TEVAR+BMS group than in the TEVAR-only group at postoperative months 6 and 12 (all p < 0.001). Aortic diameters at all 5 parts were significantly smaller in the TEVAR+BMS group than in the TEVAR-only group (all p < 0.05). CONCLUSION: In patients with subacute cTBAD, TEVAR with BMS implantation effectively expands the TL from the thoracic aorta to the RA but neither enhances aortic remodeling nor elicits any change in total aortic area in whole dissected aorta relative to TEVAR only.

Pharmacological actions of the bioactive compounds of Epimedium on the male reproductive system: current status and future perspective.

ABSTRACT: Compounds isolated from Epimedium include the total flavonoids of Epimedium, icariin, and its metabolites (icaritin, icariside I, and icariside II), which have similar molecular structures. Modern pharmacological research and clinical practice have proved that Epimedium and its active components have a wide range of pharmacological effects, especially in improving sexual function, hormone regulation, anti-osteoporosis, immune function regulation, anti-oxidation, and anti-tumor activity. To date, we still need a comprehensive source of knowledge about the pharmacological effects of Epimedium and its bioactive compounds on the male reproductive system. However, their actions in other tissues have been reviewed in recent years. This review critically focuses on the Epimedium, its bioactive compounds, and the biochemical and molecular mechanisms that modulate vital pathways associated with the male reproductive system. Such intrinsic knowledge will significantly further studies on the Epimedium and its bioactive compounds that protect the male reproductive system and provide some guidances for clinical treatment of related male reproductive disorders.

Genomic analysis of Alteromonas sp. M12 isolated from the Mariana Trench reveals its role in dimethylsulfoniopropionate cycling.

Dimethylsulfoniopropionate (DMSP) is a ubiquitous organosulfur molecule in marine environments with important roles in stress tolerance, global carbon and sulfur cycling, and chemotaxis. It is the main precursor of the climate active gas dimethyl sulfide (DMS), which is the greatest natural source of bio­sulfur transferred from ocean to atmosphere. Alteromonas sp. M12, a Gram-negative and aerobic bacterium, was isolated from the seawater samples collected from the Mariana Trench at the depth of 2500 m. Here, we report the complete genome sequence of strain M12 and its genomic characteristics to import and utilize DMSP. The genome of strain M12 contains one circular chromosome (5,012,782 bp) with the GC content of 40.88%. Alteromonas sp. M12 can grow with DMSP as a sole carbon source, and produced DMS with DMSP as a precursor. Genomic analysis showed that strain M12 contained a set of genes involved in the downstream steps of DMSP cleavage, but no known genes encoding DMSP transporters or DMSP lyases. The results indicated that this strain contained novel DMSP transport and cleavage genes in its genome which warrants further investigation. The import of DMSP into cells may be a strategy of strain M12 to adapt the hydrostatic pressure environment in the Mariana Trench, as DMSP can be used as a hydrostatic pressure protectant. This study sheds light on the catabolism of DMSP by deep-sea bacteria.

Meta-omics analysis reveals the marine arsenic cycle driven by bacteria.

Arsenic is a toxic element widely distributed in the Earth's crust and ranked as a class I human carcinogen. Microbial metabolism makes significant contributions to arsenic detoxification, migration and transformation. Nowadays, research on arsenic is primarily in areas affected by arsenic pollution associated with human health activities. However, the biogeochemical traits of arsenic in the global marine ecosystem remain to be explicated. In this study, we revealed that seawater environments were primarily governed by the process of arsenate reduction to arsenite, while arsenite methylation was predominant in marine sediments which may serve as significant sources of arsenic emission into the atmosphere. Significant disparities existed in the distribution patterns of the arsenic cycle between surface and deep seawaters at middle and low latitudes, whereas these situations tend to be similar in the Arctic and Antarctic oceans. Significant variations were also observed in the taxonomic diversity and core microbial community of arsenic cycling across different marine environments. Specifically, γ-proteobacteria played a pivotal role in the arsenic cycle in the whole marine environment. Temperature, dissolved oxygen and phosphate were the crucial factors that related to these differentiations in seawater environments. Overall, our study contributes to a deeper understanding of the marine arsenic cycle.

Alternative dimethylsulfoniopropionate biosynthesis enzymes in diverse and abundant microorganisms.

Dimethylsulfoniopropionate (DMSP) is an abundant marine organosulfur compound with roles in stress protection, chemotaxis, nutrient and sulfur cycling and climate regulation. Here we report the discovery of a bifunctional DMSP biosynthesis enzyme, DsyGD, in the transamination pathway of the rhizobacterium Gynuella sunshinyii and some filamentous cyanobacteria not previously known to produce DMSP. DsyGD produces DMSP through its N-terminal DsyG methylthiohydroxybutyrate S-methyltransferase and C-terminal DsyD dimethylsulfoniohydroxybutyrate decarboxylase domains. Phylogenetically distinct DsyG-like proteins, termed DSYE, with methylthiohydroxybutyrate S-methyltransferase activity were found in diverse and environmentally abundant algae, comprising a mix of low, high and previously unknown DMSP producers. Algae containing DSYE, particularly bloom-forming Pelagophyceae species, were globally more abundant DMSP producers than those with previously described DMSP synthesis genes. This work greatly increases the number and diversity of predicted DMSP-producing organisms and highlights the importance of Pelagophyceae and other DSYE-containing algae in global DMSP production and sulfur cycling.

Effect of ultrasonic degradation on the physicochemical characteristics, GLP-1 secretion, and antioxidant capacity of Polygonatum cyrtonema polysaccharide.

This study aimed to evaluate the influence of ultrasonic degradation on the physicochemical and biological characteristics of Polygonatum cyrtonema polysaccharide (PCP, 8.59 kDa). PCP was subjected to ultrasonic treatment for 8, 16, and 24 h and yielded the degraded fractions PCP-8, PCP-16, and PCP-24 (5.06, 4.13, and 3.69 kDa), respectively. Compared with the intact PCP, PCP-8, PCP-16 and PCP-24 had a reduced particle size (decrements of 28.03 %, 46.15 % and 62.54 %, respectively). Although ultrasonic degradation did not alter the primary structure of PCP, its triple helical and superficial structures were disrupted, with degraded fractions demonstrating reduced thermal stability and apparent viscosities compared with those of the intact PCP. Furthermore, the functional properties of the degraded fractions were different. PCP-16 most favourably affected GLP-1 secretion, while PCP-8 and PCP-24 exhibited the strongest antioxidant and enzyme inhibitory activities, respectively. Hence, controlled ultrasound irradiation is an appealing approach for partially degrading PCP and enhancing its bioactivity as a functional agent.

Identification of a novel hypoglycemic small molecule, trans-2, 4-dimethoxystilbene by rectifying gut microbiota and activating hepatic AMPKα-PPARγ pathway through gut-liver axis.

With the increasing prevalence of metabolic disorders, hyperglycemia has become a common risk factor that endangers people's lives and the need for new drug solutions is burgeoning. Trans-2, 4-dimethoxystilbene (TDMS), a synthetic stilbene, has been found as a novel hypoglycemic small molecule from glucose consumption test. Normal C57BL/6 J mice, mouse models of type 1 diabetes mellitus and diet-induced obesity subjected to TDMS gavage were found with lower glycemic levels and better glycemic control. TDMS significantly improved the symptoms of polydipsia and wasting in type 1 diabetic mice, and could rise their body temperature at the same time. It was found that TDMS could promote the expression of key genes of glucose metabolism in HepG2, as do in TDMS-treated liver, while it could improve the intestinal flora and relieve intestinal metabolic dysbiosis in hyperglycemic models, which in turn affected its function in the liver, forming the gut-liver axis. We further fished PPARγ by virtual screening that could be promoted by TDMS both in-vitro and in-vivo, which was regulated by upstream signaling of AMPKα phosphorylation. As a novel hypoglycemic small molecule, TDMS was proven to be promising with its glycemic improvements and amelioration of diabetes symptoms. It promoted glucose absorption and utilization by the liver and improved the intestinal flora of diabetic mice. Therefore, TDMS is expected to become a new hypoglycemic drug that acts through gut-liver axis via AMPKα-PPARγ signaling pathway in improving glycemic metabolism, bringing new hope to patients with diabetes and glucose metabolism disorders.

Enhanced Iturin A Production of Engineered Bacillus amyloliquefaciens by Knockout of Endogenous Plasmid and Rap Phosphatase Genes.

Iturin A biosynthesis has garnered considerable interest, yet bottlenecks persist in its low productivity in wild strains and the ability to engineer Bacillus amyloliquefaciens producers. This study reveals that deleting the endogenous plasmid, plas1, from the wild-type B. amyloliquefaciens HM618 notably enhances iturin A synthesis, likely related to the effect of the Rap phosphatase gene within plas1. Furthermore, inactivating Rap phosphatase-related genes (rapC, rapF, and rapH) in the genome of the strain also improved the iturin A level and specific productivity while reducing cell growth. Strategic rap genes and plasmid elimination achieved a synergistic balance between cell growth and iturin A production. Engineered strain HM-DR13 exhibited an increase in iturin A level to 849.9 mg/L within 48 h, significantly shortening the production period. These insights underscore the critical roles of endogenous plasmids and Rap phosphatases in iturin A biosynthesis, presenting a novel engineering strategy to optimize iturin A production in B. amyloliquefaciens.

Facile preparation of hollow covalent organic frameworks as superior and universal matrix clean-up micro-structures for high throughout determination of food hazards.

The complicated food matrix seriously limits the one-time test for the potential food hazards in non-targeted analysis. Accordingly, developing advanced sample pretreatment strategy to reduce matrix effects is of great significance. Herein, newly-integrated hollow-structured covalent organic frameworks (HCOFs) with large internal adsorption capacity and target-matched pore size were synthesized via etching the core-shell structured COFs. The as-prepared HCOFs could be directly applied for matrix clean-up of vegetable samples, while further modification of polydopamine (PDA) network facilitated application for animal samples. Both HCOFs and HCOFs@PDA with the comparable sizes to the matrix interference gave excellent adsorption performance to targets, achieving satisfied recoveries (70%-120%) toward 90 pesticides and 44 veterinary drugs in one-test, respectively. This work showed the great potential of the facile-integrated HCOFs with high stability and customized size to remove interference matrix and offered a universal strategy to achieve simultaneous screening of hazards with considerable quantity in high-throughput non-targeted analysis.

Revised evaluation objectives of the Korean Dentist Clinical Skill Test: a survey study and focus group interviews

PURPOSE: This study aimed to propose a revision of the evaluation objectives of the Korean Dentist Clinical Skill Test by analyzing the opinions of those involved in the examination after a review of those objectives. METHODS: The clinical skill test objectives were reviewed based on the national-level dental practitioner competencies, dental school educational competencies, and the third dental practitioner job analysis. Current and former examinees were surveyed about their perceptions of the evaluation objectives. The validity of 22 evaluation objectives and overlapping perceptions based on area of specialty were surveyed on a 5-point Likert scale by professors who participated in the clinical skill test and dental school faculty members. Additionally, focus group interviews were conducted with experts on the examination. RESULTS: It was necessary to consider including competency assessments for "emergency rescue skills" and "planning and performing prosthetic treatment." There were no significant differences between current and former examinees in their perceptions of the clinical skill test's objectives. The professors who participated in the examination and dental school faculty members recognized that most of the objectives were valid. However, some responses stated that "oromaxillofacial cranial nerve examination," "temporomandibular disorder palpation test," and "space management for primary and mixed dentition" were unfeasible evaluation objectives and overlapped with dental specialty areas. CONCLUSION: When revising the Korean Dentist Clinical Skill Test's objectives, it is advisable to consider incorporating competency assessments related to "emergency rescue skills" and "planning and performing prosthetic treatment."

Genomic analysis of Cobetia sp. D5 reveals its role in marine sulfur cycling.

Dimethylsulfoniopropionate (DMSP) is one of the most abundant sulfur-containing organic compounds on the earth, which is an important carbon and sulfur source and plays an important role in the global sulfur cycle. Marine microorganisms are an important group involved in DMSP metabolism. The strain Cobetia sp. D5 was isolated from seawater samples in the Yellow Sea area of Qingdao during an algal bloom. There is still limited knowledge on the capacity of DMSP utilization of Cobetia bacteria. The study reports the whole genome sequence of Cobetia sp. D5 to understand its DMSP metabolism pathway. The genome of Cobetia sp. D5 consists of a circular chromosome with a length of 4,233,985 bp and the GC content is 62.56%. Genomic analysis showed that Cobetia sp. D5 contains a set of genes to transport and metabolize DMSP, which can cleave DMSP to produce dimethyl sulphide (DMS) and 3-Hydroxypropionyl-Coenzyme A (3-HP-CoA). DMS diffuses into the environment to enter the global sulfur cycle, whereas 3-HP-CoA is catabolized to acetyl CoA to enter central carbon metabolism. Thus, this study provides genetic insights into the DMSP metabolic processes of Cobetia sp. D5 during a marine algal bloom, and contributes to the understanding of the important role played by marine bacteria in the global sulfur cycle.

Construction of blackberry polysaccharide nano-selenium particles: Structure features and regulation effects of glucose/lipid metabolism in HepG2 cells.

In this study, blackberry polysaccharide-selenium nanoparticles (BBP-24-3Se) were first prepared via Na2SeO3/Vc redox reaction, followed by coating with red blood cell membrane (RBC) to form core-shell structure polysaccharide-selenium nanoparticles (RBC@BBP-24-3Se). The particle size of BBP-24-3Se (167.1 nm) was increased to 239.8 nm (RBC@BBP-24-3Se) with an obvious core-shell structure after coating with RBC. FT-IR and XPS results indicated that the interaction between BBP-24-3 and SeNPs formed a new C-O···Se bond with valence state of Se0. Bioassays indicated that RBC coating markedly enhanced both the biocompatibility and bioabsorbability of RBC@BBP-24-3Se, and the absorption rate of RBC@BBP-24-3Se in HepG2 cells was 4.99 times higher than that of BBP-24-3Se at a concentration of 10 µg/mL. Compared with BBP-24-3Se, RBC@BBP-24-3Se possessed significantly heightened protective efficacy against oxidative damage and better regulation of glucose/lipid metabolism disorder induced by palmitic acid in HepG2 cells. Mechanistic studies demonstrated that RBC@BBP-24-3Se could effectively improve PI3K/AKT signaling pathway to promote glucose metabolism, inhibit the expression of lipid synthesis genes and up-regulate the expression of lipid-decomposing genes through AMPK signaling pathway to improve lipid metabolism. These results provided a theoretical basis for developing a new type of selenium supplement for the treatment of insulin resistance.

Construction of a 3D Quantum Dot Nanoassembly with Two-Step FRET for One-Step Sensing of Human Telomerase RNA in Breast Cancer Cells and Tissues.

Telomerase is an important biomarker for early diagnosis of cancers, but current telomerase assays usually rely on measuring the extension products of telomerase substrates, which increases the assay complexity. More evidence indicates that human telomerase RNA (hTR), as a core component of telomerase, is positively correlated with the telomerase activity. Herein, we demonstrate the development of a duplex-specific nuclease (DSN)-propelled 3D quantum dot (QD) nanoassembly with two-step Föster resonance energy transfer (FRET) for the one-step sensing of hTR in breast cancer cells and tissues. This assay involves only one hairpin probe modified with a Cy5 at the sixth base from the 5'-biotin end and a BHQ2 at the 3'-terminus, which integrates three functions of target recognition, target recycling amplification, and signal readout. The anchoring of the hairpin probe on the 605QD surface results in the formation of a 3D 605QD-Cy5-probe-BHQ2 nanoassembly in which two-step FRET occurs among the 605QD, Cy5, and BHQ2 quencher. Notably, the formation of 605QD-Cy5-probe-BHQ2 nanoassembly facilitates the reduction of background signal and the increase of signal-to-background ratio due to its dense, highly oriented nucleic acid shell-induced steric hindrance effect. This assay can achieve one-step and rapid detection of hTR with a detection limit of 2.10 fM, which is the simplest and most rapid hTR assay reported so far. Moreover, this assay can efficiently distinguish single-base mismatched sequences, and it can discriminate the hTR level between breast cancer patients and healthy donors with a high accuracy of 100%, with great prospects for early diagnosis of cancers.