Dynamic surface reconstruction of individual gold nanoclusters by using a co-reactant enables color-tunable electrochemiluminescence.

Here we report for the first time the phenomenon of continuously color-tunable electrochemiluminescence (ECL) from individual gold nanoclusters (Au NCs) confined in a porous hydrogel matrix by adjusting the concentration of the co-reactant. Specifically, the hydrogel-confined Au NCs exhibit strong dual-color ECL in an aqueous solution with triethylamine (TEA) as a co-reactant, with a record-breaking quantum yield of 95%. Unlike previously reported Au NCs, the ECL origin of the hydrogel-confined Au NCs is related to both the Au(0) kernel and the Au(i)-S surface. Surprisingly, the surface-related ECL of Au NCs exhibits a wide color-tunable range of 625-829 nm, but the core-related ECL remains constant at 489 nm. Theoretical and experimental studies demonstrate that the color-tunable ECL is caused by the dynamic surface reconstruction of Au NCs and TEA radicals. This work opens up new avenues for dynamically manipulating the ECL spectra of core-shell emitters in biosensing and imaging research.

Identification and Quantification of 5-Methylcytosine and 5-Hydroxymethylcytosine on Random DNA Sequences by a Nanoconfined Electrochemiluminescence Platform.

5-Methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) are two of the most abundant epigenetic marks in mammalian genomes, and it has been proven that these dual epigenetic marks give a more accurate prediction of recurrence and survival in cancer than the individual mark. However, due to the similar structure and low expression of 5mC and 5hmC, it is challenging to distinguish and quantify the two methylation modifications. Herein, we employed the ten-eleven translocation family dioxygenases (TET) to convert 5mC to 5hmC via a specific labeling process, which realized the identification of the two marks based on a nanoconfined electrochemiluminescence (ECL) platform combined with the amplification strategy of a recombinase polymerase amplification (RPA)-assisted CRISPR/Cas13a system. Benefiting from the TET-mediated conversion strategy, a highly consistent labeling pathway was developed for identifying dual epigenetic marks on random sequence, which reduced the system error effectively. The ECL platform was established via preparing a carbonized polymer dot embedded SiO2 nanonetwork (CPDs@SiO2), which exhibited higher ECL efficiencies and more stable ECL performance compared to those of the scattered emitters due to the nanoconfinement-enhanced ECL effect. The proposed bioanalysis strategy could be employed for the identification and quantification of 5mC and 5hmC in the range from 100 aM to 100 pM, respectively, which provides a promising tool for early diagnosis of diseases associated with abnormal methylation.

Two new compounds from edible mushroom Sarcomyxa edulis.

Chemical investigation of the edible mushroom Sarcomyxa edulis led to the isolation of one new highly degraded sterol (1), and one new ß-carboline alkaloid (2), along with nine known compounds (3-11) for the first time from this mushroom. The structures of new compounds were elucidated using HR-ESI-MS data and NMR spectroscopy. In addition, anti-inflammatory activity of new compounds was evaluated against lipopolysaccharide-induced NO production in RAW 264.7 macrophages. Compound 2 exhibited a good anti-inflammatory activity with IC50 value of 9.88 ± 0.48 µM, and compound 1 exhibited a weak inhibitory effect with IC50 value of 71.36 ± 5.11 µM.

Wireframe Orbit-Accelerated Bipedal DNA Walker for Electrochemiluminescence Detection of Methyltransferase Activity.

In spite of the DNA walkers executing the signal accumulation task in the process of moving along the predetermined paths, the enhancement of walking dynamics and walking path controllability are still challenging due to the unprogrammed arrangements of DNA orbits. Taking these dilemmas into account, a bipedal DNA walker was designed skillfully by the virtue of wireframe orbits assembled by DNA cubes in order, which improved the efficiency and the continuity of walking. It could be attributed to the fact that both the contact chance and the dynamic interaction between walking strands and designated orbits were beneficial to minimize the possibility of derailment and improve the accumulation of signal. In addition, the hollow titanium dioxide nanospheres coated with rubrene (Rub@TiO2 NSs) were prepared by the etching of inner silicon dioxide nanoparticles (SiO2 NPs) to regulate the distribution pattern of rubrene (Rub) molecules and expose more electrochemically active sites for high-efficient electrochemiluminescence (ECL). Benefiting by the pore confinement-enhanced ECL, the electron and mass transfer was significantly accelerated because of the hollow structure of Rub@TiO2 NSs. Subsequently, endogenous dissolved oxygen as the coreactant and palladium nanoparticles (Pd NPs) as the coreaction accelerator were employed to constitute a ternary ECL system with explosive signal response. Combining with this ECL platform, the bipedal walker activated by the target can autonomously and directionally move on the DNA wireframe orbits to release the quenching probes continuously. In this way, the biosensor displayed a low detection limit (2.30 × 10-8 U·mL-1) and a wide linear range (1.0 × 10-7 to 1.0 × 10-1 U·mL-1) for the sensitive detection of Dam methyltransferase (Dam MTase) activity. Therefore, a novel strategy for the accurate quantification of epigenetic targets was developed by virtue of improving the walking dynamics of DNA walker and amplifying the ECL of Rub molecules.

Morpho-Molecular Evidence Reveals Four Novel Species of Gymnopus (Agaricales, Omphalotaceae) from China.

Nine collections of gymnopoid fungi were studied based on morpho-molecular characteristics. The macromorphology was made according to the photograph of fresh basidiomata and field notes, while the micromorphology was examined via an optical microscope. Simultaneously, the phylogenetic analyses were performed by maximum likelihood and Bayesian inference methods based on a combined dataset of nrITS1-nr5.8S-nrITS2-nrLSU sequences. Integrated analysis of these results was therefore, G. efibulatus belonging to sect. Androsacei, G. iodes and G. sinopolyphyllus belonging to sect. Impudicae and G. strigosipes belonging to sect. Levipedes are proposed as new to science. The detailed descriptions, colour photos of basidiomata and line-drawings of microscopic structures are provided. The comparisons with closely related species and a key to known species of Gymnopus s. str. reported with morpho-molecular evidence in China is also given.

Swing Arm Location-Controllable DNA Walker for Electrochemiluminescence Biosensing.

Here, we described a novel swing arm location-controllable DNA walker based on the DNA tetrahedral nanostructures (DTNs) for nucleic acid detection using the polycyclic aromatic hydrocarbon (PAH) microcrystals (TAPE-Pe MCs) consisting of the nonplanar molecular tetrakis(4-aminophenyl)ethene (TAPE) and planar molecular perylene (Pe) as electrochemiluminescence (ECL) luminophores. Specifically, the swing arm strands and track strands were fixed simultaneously on the DTNs to obtain the location-controllable DNA walker, which possessed an improved reaction efficiency compared to that of a fixed swing arm-based DNA walker due to the quantitative and orderly swing arm on the DTNs. On the other hand, the Pe microcrystals doped by TAPE molecules could decrease the π-π stacking of Pe molecules for the ECL efficiency enhancement, achieving a blue-shifted and intense ECL emission. Therefore, we defined this enhanced and blue-shifted ECL phenomenon as "inhibition of conjugation-driven ECL (IC-ECL)". To prove these principles, a location-controllable DNA walker-based ECL biosensor was developed with microRNA let-7a as target molecules. The ECL biosensor achieved a low detection limit of 4.92 fM within a wide linear range from 10 fM to 100 nM. This approach offers a new insight for ECL efficiency increase and location-controllable strategies with improved reaction efficiency, demonstrating potential in diagnostic analysis.

In Situ Controllable Generation of Copper Nanoclusters Confined in a Poly-l-Cysteine Porous Film with Enhanced Electrochemiluminescence for Alkaline Phosphatase Detection.

Copper nanoclusters (Cu NCs) as emerging luminescent metal NCs are gaining increasing attention owing to the comparatively low cost and high abundance of the Cu element in nature. However, it remains challenging to manipulate the optical properties of Cu NCs. Unlike most dispersed Cu NCs, whose luminescence efficiency was restricted by nonexcited relaxation, the Cu NCs confined in a porous poly-l-cysteine (poly-l-Cys) film were generated controllably with enhanced electrochemiluminescence (ECL) by in situ electrochemical reduction. Specifically, poly-l-Cys provided a porous structure to regulate the generation of Cu NCs within its holes, which not only increased the restriction on the intramolecular vibration and rotation of the ligands but also expedited the electron transfer near the electrode surface, reflecting in an enhancement of the ECL signal and efficiency. As an application of the confined Cu NCs, an ECL biosensor with high performance was constructed skillfully for highly sensitive detection of alkaline phosphatase (ALP), which adopted Cu NCs as the ECL luminophore and poly-l-Cys as a coreaction accelerator in a novel ECL ternary system (Cu NCs/S2O82-/poly-l-Cys). Furthermore, an ingenious target amplification based on the combination of a DNA walker and click chemistry was developed to convert ALP to DNA strands efficiently, achieving great improvement in the recognition efficiency. As a result, the biosensor had a low detection limit (9.5 × 10-7 U·L-1) and a wide linear range (10-8-10-2 U·L-1) for ALP detection, which showed great promise for the detection of non-nucleic acid targets and the diagnosis of diseases.

Residual Negative Pressure in Vacuum Blood-Collection Tube and Hemolysis in Pediatric Blood Specimens.

OBJECTIVE: To determine a method to reduce specimen hemolysis rates in pediatric blood specimens. METHODS: A total of 290 blood specimens from pediatric patients were classified into the capped group or uncapped group. The hemolysis index and levels of lactate dehydrogenase (LDH) were measured using an automated biochemical analyzer. Also, we performed a paired test to measure the concentration of free hemoglobin in specimens from 25 randomly selected healthy adult volunteers, using a direct spectrophotometric technique. RESULTS: The hemolytic rate of capped specimens was 2-fold higher than that of uncapped specimens. We found significant differences for LDH. Also, there was a significant difference in the concentration of free hemoglobin in the random-volunteers test. CONCLUSIONS: Eliminating the residual negative pressure of vacuum blood-collection tubes was effective at reducing the macrohemolysis and/or microhemolysis rate.

Molecular Epidemiological Characterization and Health Burden of Thalassemias in the Chaoshan Region, People's Republic of China.

Thalassemia is one of the most prevalent inherited disease in southern China. However, there have been only a few epidemiological studies of thalassemia in the Chaoshan region of Guangdong Province, People's Republic of China (PRC). A total of 6231 unrelated subjects in two main geographical cities of the Chaoshan region was analyzed for thalassemia. Seven hundred and thirty-six cases of suspected thalassemia carriers with microcytosis [mean corpuscular volume (MCV) <82.0 fL] were found by complete blood cell (CBC) count, and were tested by reverse dot-blot gene chip to reveal a total of 331 mutant chromosomes, including 278 α-thalassemia (α-thal) alleles and 53 ß-thalassemia (ß-thal) alleles. The most common α-thal mutations were the Southeast Asian (- -(SEA)), followed by the -α(3.7) (rightward) and -α(4.2) (leftward) deletions. The two most common ß-thal mutations were HBB: c.316-197C>T and HBB: c.126_129delCTTT, accounting for 69.81% of the ß-thal defects in the studied individuals. In addition, a rare mutation, Cap +1 (A>C) (HBB: c.-50A>C) was described for the first time in the Chaoshan region. Our results gave a heterozygote frequency of 5.31% for common α- and ß-thal in the Chaoshan region, and also indicated a higher prevalence of thalassemia with a heterozygote frequency of 6.29% in Chaozhou, followed by Shantou (3.37%). This study provided a detailed prevalence and molecular characterization of thalassemia in the Chaoshan region, and will be valuable for developing a strategy for prevention of thalassemia and reducing excessive health care costs in this area.

High resolution melting analysis: a rapid screening and typing tool for common ß-thalassemia mutation in Chinese population.

ß-thalassemia is a common inherited disorder worldwide including southern China, and at least 45 distinct ß-thalassemia mutations have been identified in China. High-resolution melting (HRM) assay was recently introduced as a rapid, inexpensive and effective method for genotyping. However, there was no systemic study on the diagnostic capability of HRM to identify ß-thalassemia. Here, we used an improved HRM method to screen and type 12 common ß-thalassemia mutations in Chinese, and the rapidity and reliability of this method was investigated. The whole PCR and HRM procedure could be completed in 40 min. The heterozygous mutations and 4 kinds of homozygous mutations could be readily differentiated from the melting curve except c.-78A>G heterozygote and c.-79A>G heterozygote. The diagnostic reliability of this HRM assay was evaluated on 756 pre-typed genomic DNA samples and 50 cases of blood spots on filter paper, which were collected from seven high prevalent provinces in southern China. If c.-78A>G heterozygote and c.-79A>G heterozygote were classified into the same group (c.-78&79 A>G heterozygote), the HRM method was in complete concordance with the reference method (reverse dot blot/DNA-sequencing). In a conclusion, the HRM method appears to be an accurate and sensitive method for the rapid screening and identification of ß-thalassemia mutations. In the future, we suggest this technology to be used in neonatal blood spot screening program. It could enlarge the coverage of ß-thalassemia screening program in China. At the same time, its value should be confirmed in prospectively clinical and epidemiological studies.

Development and evaluation of a reverse dot blot assay for the simultaneous detection of common alpha and beta thalassemia in Chinese.

Thalassemia is the commonest inherited autosomal recessive disorders of hemoglobin in southern China. We developed and evaluated a reverse dot blot (RDB) assay combined with flow-through hybridization technology platform for the rapid and simultaneous identification of 5 types of α-thalassemia and 16 types of ß-thalassemia common in Chinese. Reliable genotyping of wild-type and thalassemic genomic DNA samples was achieved by means of a gene chip on which allele-specific oligonucleotide probes were immobilized on a nylon membrane. This method involved two multiplex PCR amplification systems of α-thalassemia and ß-thalassemia and one time of hybridization. The whole procedure starting from blood sampling to the identification of thalassemia genotype required less than 4h. The diagnostic reliability of this reverse dot blot assay was evaluated on 427 samples (387 cases of thalassemia and 40 healthy persons) by using direct DNA sequence analysis and gap-PCR in a blind study. These samples included 377 cases of blood, 7 cases of amniotic fluid, 18 cases of chorionic villus, and 25 cases of cord blood. The RDB gene chip was in complete concordance with the reference method. The reverse dot blot assay was a simple, rapid, accurate, and cost-effective method to identify common thalassemia genotypes in the Chinese population.