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The development of amplification strategies is one of the central challenges for detection of low-abundance targets. One-to-many (1:M) amplification strategies in which one target lights many signal probes, has improved the detection sensitivity in bulk solution, but with discounted contrast in cell imaging, because the lighted probes are dissociative and dispersible. In this work, a one-to-large (1:L) signaling mechanism, in which the lighted probes were orderly connected to each other, was conceptually proposed to enhance the contrast in cell imaging by avoiding signal dispersion in amplification. Accordingly, target-triggered hairpin-free chain-branching assembly (HFCBA) holds great potential to implement the 1:L mechanism, but using it in cell imaging has yet to be demonstrated. As a proof of concept, a group of probes were first programmed to implement miRNA-21-triggered HFCBA. After transfection of probes, gradually-growing signal flares in cells were monitored along with the growth of DNA dendrimers; and the in situ fluorescence accumulation in HFCBA resulted in highly-enhanced contrast to the surrounding by avoiding signal dispersion in amplification. The contrast-enhanced imaging with signal amplification is significant for biological analysis and molecular medicine. We expect the 1:L mechanism will provide a new thought for high-performance imaging of biomarkers in cells.

In order to study the bridge deflection monitoring and prediction system based on network communication, first, the development status of the bridge deflection monitoring system, overall demand of the system, hardware composition of the system, realization of the system software, and the timely processing and analysis of monitoring data are discussed. Then, the dynamic prediction of the change trend of the external load and the decay information of the structural resistance contained in the deflection monitoring data is carried out, and the prediction function of the external effect of the structure is established at the same time. Finally, a rapid monitoring system specially designed to deal with accidental bridge disasters was developed, and it was installed and applied in the engineering experiment of Chongqing Gaojia Garden Bridge. The deflection data analysis of Gaojia Huayuan Bridge was carried out, and suggestions for the operation and maintenance of the bridge were put forward, and the safety status assessment of the bridge was realized. The results show that the system has strong practicability, real-time monitoring and accuracy. It provides a convenient and accurate way for bridge managers to supervise bridges and formulate specific bridge maintenance plans in a timely manner. During the radio frequency modulation of communication data, harmonic oscillations occur due to the nonlinear characteristics of oscillating data, so it is difficult to improve the wireless ability to modulate and demodulate transmitted data in communications. The traditional method uses neural network fuzzy control distribution estimation harmonic balance algorithm and nonlinear rolling. The performance of dynamic predictive control is poor in quality, harmonic balance, and stability control. An improved harmonic-based communication network is proposed to balance the stability control model of nonlinear communication system, construct nonlinear communication system model, and extract signal and channel characteristics of the communication system. The channel model is designed and the communication network control method is adopted to improve the control algorithm. The simulation results show that the proposed algorithm can be used to improve the stability of nonlinear communication system, reduce the bit error rate, overcome the interference of coherent component in sidelobe, and autocorrelated the impulse response of receiver. The stability of the cumulative output is good, which can overcome the communication error caused by the harmonic oscillation due to the nonlinear characteristics of the oscillating data, and improve the communication quality.

Metal-coordination-directed biomolecule crosslinking in nature has been used for synthesizing various biopolymers, including DNA, peptides, proteins, and polysaccharides. However, the RNA biopolymer has been avoided so far, as due to the poor stability of the RNA molecules, the formation of a biopolymer may alter the biological function of the molecules. Herein, for the first time, we report Zn2+ -driven RNA self-assembly forming spherical nanoparticles while retaining the integrity and biological function of RNA. Various functional RNAs of different compositions, shapes, and lengths from 20 to nearly 1000 nucleotides were used, highlighting the versatility of this approach. The assembled nanospheres possess a superior RNA-loading efficiency, pharmacokinetics, and bioavailability. In-vitro and in-vivo evaluation demonstrated mRNA delivery for expressing GFP proteins, and microRNA delivery to triple-negative breast cancer. This coordination-directed self-assembly behavior amplifies the horizons of RNA coordination chemistry and the application scope of RNA-based therapeutics.

The peroxidase-like activity of nanozymes is promising for chemodynamic therapy by catalyzing H2 O2 into . OH. However, for most nanozymes, this activity is optimal just in acidic solutions, while the pH of most physiological systems is beyond 7.0 (even >8.0 in chronic wounds) with inadequate H2 O2 . We herein communicate an activatable nanozyme with targeting capability to simultaneously break the local pH and H2 O2 limitations under physiological conditions. As a proof of concept, aptamer-functionalized nanozymes, glucose oxidase, and hyaluronic acid constitute an activatable nanocapsule "APGH", which can be activated by bacteria-secreted hyaluronidase in infected wounds. Nanozymes bind onto bacteria through aptamer recognition, and glucose oxidation tunes the local pH down and supplements H2 O2 for the in-situ generation of . OH on bacteria surfaces. The activity switching and enhanced antibacterial effect of the nanocapsule were verified in vitro and in diabetic wounds. This strategy for directly regulating local microenvironment is generally accessible for nanozymes, and significant for facilitating biological applications of nanozymes.

Seamount is a unique deep-sea ecosystem widely distributed in the world. Its biodiversity is vibrant due to its specific geographical and hydrological conditions. However, the diversity and features of foraminifera in such an environment have rarely been studied. We extracted environmental DNA (eDNA) in sediments and amplified the partial small subunit ribosomal DNA (SSU rDNA) of foraminifera to understand the foraminiferal diversity from four sites in Magellan Seamount (Western Pacific Ocean). Partial SSU rDNA sequencing was conducted and 912 979 foraminiferal reads were obtained and gathered into 266 operational taxonomic units (OTUs). In the available dataset, a high proportion of rare OTUs and low identity OTUs in each studied sample showed that the Magellan Seamount foraminiferal community might have a high genetic novelty. The relative abundance of foraminifera varied between replicates probably due to the existence of bias in amplification process and patchiness of the deep-sea floor. It showed that the Magellan Seamount has a relatively high benthic foraminiferal diversity characterized mainly by monothalamiids (76.37% of total reads) in association with rotaliids (19.03% of total reads), including planktic foraminiferal sequences (38.58% of rotaliids; 7.36% of total reads). The remaining reads were assigned to miliolids (0.83% of total reads) and textulariids (0.66% of total reads), and 3.11% of total reads are unassigned to a specific family. The comparative analysis with foraminiferal assemblages from coastal and deep-sea environments indicated that seamounts could aggregate species from a nearby deep-sea.

It is critical to improve the efficiency of cancer therapy with minimized side effects. Chemodynamic therapy (CDT) is a tumor therapeutic strategy designed to generate abundant reactive oxygen spec...

A clamp-like triplex switch (CTS) able to simultaneously downregulate an overexpressed onco-miRNA and replenish the lost tumor-suppressive miRNA in a controllable manner was developed for enhanced gene therapy. Compared to the "unidirectional" regulation approach, the CTS displayed improved anti-tumor efficacy in vitro and was harmless to healthy cells.

The ocean absorbs large amounts of CO2 emitted from human activities, which lead a decrease in seawater pH and has potential damage to marine calcareous organisms. Foraminifera is one of the most important marine calcareous organisms in the ocean, while the biological response of benthic and planktic foraminifera to seawater CO2 increase and pH decline is still unknown. In this study, a comparison of the biological response of benthic and planktic foraminifera to seawater CO2 increase and pH decline was studied through series of culture experiments. Our experimental results showed the increase of CO2 or decrease of seawater pH adversely affected the biological processes of both benthic and planktic foraminifera may resulted in declining community diversity, weaker predation, slower growth, lighter shells and more deformities. In addition, we found microalgae that lives with planktic foraminifera are also killed under low pH conditions. Our study provided experimental data for understanding the biological response of calcareous micro-organisms to ocean acidification. Our results indicated that ongoing ocean acidification may retard the growth and calcification by changing their biological processes. This would have profound effects (e.g., reduced carbonate deposition and predation) on the carbon cycle and energy flow in the marine food web (This research received financial supports from the following projects: National Natural Science Foundation of China (Grant No, 41976058); The Strategic Priority Research Program of the Chinese Academy of Sciences (XDB42000000).

This study explored the response to salinity of intertidal foraminiferal assemblages from the Yellow Sea by culturing them for 100 days at six constant salinity levels (17, 22, 27, 32, 37, and 42 psu) in laboratory microcosms with four replicates each. A total of 7,471 live (stained) foraminiferal specimens were obtained and analyzed. The diversity parameters of foraminiferal assemblages (species richness, Margalef index, Shannon-Wiener index, and Fisher's alpha) declined significantly when the salinity was increased or decreased from the field value, but foraminiferal abundance was highly resistant to salinity. In addition, salinity exerted different effects on foraminifera from different orders. Specifically, the proportion of species from Order Miliolida significantly increased whereas that of species from Order Rotaliida decreased with increasing salinity. High salinity-tolerant species Ammonia aomoriensis, Cribrononion gnythosuturatum, Ammonia tepida, and Quinqueloculina seminula could fill unoccupied ecological niches when the proportion of salinity-sensitive species has declined. Furthermore, our morphometric results showed that foraminiferal test size was significantly negatively correlated with salinity, and numerous abnormal specimens appeared in foraminiferal assemblages when salinity deviated from the field value. Our study revealed that intertidal foraminiferal assemblages had high adaptability at different salinities because of the existence of high salinity-tolerant dominant species. In addition, salinity variation can significantly alter foraminiferal morphology in test size and abnormality.

Proximity-dependent hybridization chain reaction (HCR) has shown great potential in sensing biomolecules on the cell surface. However, the requirement of two adjacent bioevents occurring simultaneously limits its application. To solve the problem, split aptamers with target binding ability were introduced to combine with split triggers for initiating HCR, thus producing a novel dual-split aptamer probe (DSAP). By employing cancer-related receptors as models, in situ HCR on a cancer cell surface induced by recognition-driven remodeling of the DSAP was demonstrated. The DSAP consisted of two sequences. Each contained two segments; one derived from split aptamers and the other originated in split triggers. In the presence of target cells, split aptamers reassembled on the cell surface under the "induced-fit effect", thus forcing two split triggers close to each other. The remodeled DSAP worked as an intact trigger, which opened the H1 hairpin probe and then hybridized with the H2 hairpin probe, thus initiating HCR to produce an activated fluorescence signal. As a proof of concept, human liver cancer SMMC-7721 cells and their split ZY11 aptamer were used to construct the DSAP. Results indicated that the DSAP realized sensitive analysis of target cells, permitting the actual detection of 20 cells in the buffer. Moreover, the specific identification of target cells in mixed cell samples and the quantitative analysis of target cells in serum were also achieved. The DSAP strategy is facile and universal, which not only would expand the application range of HCR but also might be developed as a multitarget detection technique for bioanalysis.

Nucleic acids are recognized as the blueprints of life and the repositories of genetic information, which play essential roles in the "central dogma of molecular biology". As classical and specific nucleic acids, apart from carrying genetic information, functional nucleic acids (FNAs) perform many intriguing functions such as targeted recognition, therapy and enzymatic catalysis. FNAs with excellent biocompatibility provide great promise for future applications in bioanalysis, material science, and nanotechnology. Nevertheless, effective delivery of FNAs to the targeted location still suffers from one or more challenges, especially in the field of biomedicine. Encouragingly, DNA nanotechnology shows great potential for applications in bioimaging, biosensing, and molecules delivery. Importantly, it provides an unprecedented opportunity to design and synthesize a series of self-assembled DNA nanostructures with well-defined size, shape, surface chemistry, and function. Through Watson-Crick base-pairing rules, FNAs, including aptamers, DNAzymes, small interfere RNA (siRNA), antisense oligonucleotides (ASOs), and unmethylated cytosine-phosphate-guanine dinucleotide oligonucleotides (CpG ODNS), are successfully decorated with self-assembled DNA nanostructures for delivery. In this progress report, we focus on self-assembled DNA nanostructures-based nanocarriers to deliver FNAs for applications in cellular analysis and cancer theranostics. First, we briefly summarize the superior properties of the prospective nanocarriers and introduce the self-assembled DNA nanostructures. Then we mainly highlight the most recent achievements of self-assembled DNA nanostructures as comers for the delivery of FNAs. Finally, this review points to some of the current challenges in the applications of self-assembled DNA nanostructures as FNAs nanocarriers and provides an insight into the future perspectives of self-assembled DNA nanostructures-based nanocarriers for FNAs delivery.

An Al centre-powered graphitic nanozyme derived from a metal organic framework was first developed for a chemodynamic tumor treatment. By virtue of the rapid and efficient generation of ˙OH in the slightly acidic tumor microenvironment, this nanozyme afforded high anti-tumor efficacy both in living cells and in vivo.

Aptamers are promising in cancer diagnosis and therapy, but their poor affinity under physiological conditions is a challenge. In view of the acidic microenvironment of solid tumors, we herein developed an extracellular pH-manipulated multivalent approach to exclusively improve the affinity to target cells at physiological temperature. Specifically, an aptamer based DNA monomer (AptDM) with split i-motif fragments overhanging was rationally designed, it possessed pH-responsiveness and doxorubicin loading capacity. At neutral pH, AptDMs existed as well dispersed small units, showing weakly undesired binding and internalization. In acidic extracellular conditions, AptDMs tended to crosslink of each other into multivalent DNA assemblies (MDAs) via formation of an intermolecular i-motif structure. Due to the multivalent effect, the resulting MDAs showed greatly enhanced affinity (Kd = 9.96 ± 1.06 nM) and stable binding ability at 37 °C, thus allowing highly sensitive diagnosis, efficient drug delivery, and improved inhibition to target tumor cells, but decreased cytotoxicity to nontarget cells. It is believed that this multivalent approach may boost the development of novel aptamer functionalized nanodevices for clinical validation.

Fertilization and early embryonic development as the beginning of a new life are key biological events. Hydrogen polysulfide (H

Herein, based on a terminal deoxynucleotidyl transferase (TdT)-mediated superlong poly-T-templated-copper nanoparticles (poly T-CuNPs) strategy, a simple, universal and label-free fluorescent biosensor for the detection of miRNA was constructed by employing graphene oxide (GO) and DNase I. In this strategy, GO and DNase I were used as a switch and amplifier of the signal generation pathway, respectively, and the fluorescence of poly T-CuNPs was used as the signal output. In the presence of target miRNA, the DNA dissociated from the GO surface by forming a miRNA/DNA duplex and was degraded by DNase I. The short oligos with 3'-OH, the product of DNase I degradation, could be recognized by the TdT and added to a long poly-T tail. Finally, the fluorescence signal was output through the synthesis of poly T-CuNPs. As a proof of concept, let-7a was analyzed. The method showed good sensitivity and selectivity with a linear response in the 50 pM-10,000 pM let-7a concentration range and a 30 pM limit of detection (LOD = 30 pM, R

Nano-antibacterial agents can play a critical role in chronic wound management. However, the design of an intelligent nanosystem that can provide both a visual warning of infection and precise sterilization remains a hurdle. Herein, a rod-like porphyrin-based metal-organic framework theranostic nanosystem (Zn-TCPP nanorods) is fabricated via coordination chelation between tetrakis(4-carboxylphenyl)porphyrin and zinc ions. This system can show significant fluorescence activation in response to the local elevated pH shown by chronic wounds, a main indicator of wound infection. Meanwhile, under the guidance of fluorescence imaging, the highly spatiotemporally precise photodynamic inactivation of microorganisms can be carried out without the destruction of surrounding normal cells and nascent cells. The results demonstrated that the Zn-TCPP nanorods were a highly sensitive and reversible probe for sensing alkaline pH levels. Alterations in the fluorescence of the Zn-TCPP nanorods can accurately indicate the infection status and heterogeneity of infection within the wound bed. Under specific light irradiation, the Zn-TCPP nanorods can exterminate 97% of Staphylococcus aureus via the generation of reactive oxygen species (ROS). Assays of extensive wounds demonstrate that the precise fluorescence-imaging-guided suppression of bacterial infection can significantly reduce the mouse mortality rate and accelerate wound healing. This system provides the opportunity for "precision medicine" relating to chronic wounds and some large-area wounds.

Metal-coordination-directed biomolecule crosslinking in nature has been used for synthesizing various biopolymers, including DNA, peptides, proteins, and polysaccharides. However, the RNA biopolymer has been avoided so far, as due to the poor stability of the RNA molecules, the formation of a biopolymer may alter the biological function of the molecules. Herein, for the first time, we report Zn

The peroxidase-like activity of nanozymes is promising for chemodynamic therapy by catalyzing H

Enzyme-free amplification techniques based on dynamic DNA self-assembly (DDSA) have recently been developed for the in situ detection of mRNA in living cells. However, signal generation in traditional DDSA amplifiers is mainly dependent on the random diffusion of dissociative probes in a bulk solution, which is generally accompanied by poor kinetics and interference from complex biological systems. In this work, a new amplifier based on the design of an intramolecular catalytic hairpin assembly (intra-CHA) is proposed for the FRET imaging of mRNA in living cells. Compared with that in the free catalytic hairpin assembly (free-CHA), probes H1 and H2 in intra-CHA were simultaneously fixed on a DNA tetrahedron. The distance between them was closer, the local concentration of H1 and H2 in intra-CHA was theoretically approximately 808-times higher than that in free-CHA, and the initial reaction rate was enhanced 15.6 fold. Due to the spatial confinement effect, the reaction kinetics for target-catalyzed signal generation were significantly improved. By virtue of the three-dimensional nanostructure, H1 and H2 in the intra-CHA amplifier entered cells without any transfection or nanocarrier, and the probes and their products were free from biological interference, providing much higher signal stability for the reliable imaging of mRNA in living cells., An intramolecular catalytic hairpin assembly is implemented on a DNA tetrahedron for mRNA imaging in living cells. The spatial confinement effect enables the acceleration of target-triggered signal generation, with excellent cell permeability and FRET signal stability.

It has been reported that PIWI-interacting RNAs (piRNAs) play critical roles in activating invasion and metastasis, evading growth suppressors, and sustaining proliferative signaling of cancer and can be regarded as a novel biomarker candidate. Thus, it is necessary to develop an effective method for imaging and regulating cancer-related piRNAs to diagnose and treat cancers. Herein, we designed aptamer-functionalized activatable DNA tetrahedron nanoprobes (apt-ADTNs) to image and regulate endogenous piRNAs in cancer cells. As proof of concept, overexpressed piRNA-36026 in MCF-7 cells was used for this study. In brief, aptamer AS1411 and piRNA-36026 antisequence with Cy5 fluorescent dye are appended from the DNA tetrahedron; then, a short oligonucleotide with black hole quencher 2 (Q-oligo) is complementary with piRNA-36026 antisequence to quench the fluorescence of Cy5. The apt-ADTNs can recognize the MCF-7 cells through aptamer AS1411, and then enter the cells. Q-oligo is detached from the apt-ADTNs because of the binding between apt-ADTNs and piRNA-36026, leading to the recovery of the Cy5 fluorescence signal. Meanwhile, the hybridization of apt-ADTNs and piRNA-36026 results in down-regulating of dissociative piRNA-36026 in cytoplasm and the subsequent apoptosis of MCF-7 cells. As the achievement of synchronously imaging and regulating piRNA-36026 in MCF-7 cells, we believe that this design holds great promise in application of diagnosis and therapy for cancer.

The ocean absorbs large amounts of CO2 emitted from human activities, which results in a decrease in seawater pH. Marine calcifying organisms such as foraminifera, are most likely to be affected by this declining pH. In this study, we collected sediments from five stations of different depths (34–73 m) in a continental shelf of the Yellow Sea. The entire benthic foraminiferal communities together with sea sediments were cultured under three constant pHs (8.3, 7.8, and 7.3) for 6 and 12 weeks in the laboratory to study their responses to pH or incubation time. The microcosm’s experimental results obtained showed that most of the foraminiferal community parameters (abundance, species richness, Margalef index, and Shannon-Wiener diversity) decreased significantly (p

Trace elements incorporated in foraminiferal test are commonly used as paleoproxies, however, the incorporation of trace elements is controlled by more than one environmental parameter. We conducted one year sampling from June 2014 to May 2015 in the Qingdao intertidal flat, the Yellow Sea, and retrieved surface samples in the Jiaozhou Bay (3.9–6.8 m water depth), the Yellow Sea in February 2015, as well as performed a laboratory culture experiment under temperature 6–24 °C and salinity 24–33 psu, by combining δ18Oc values of field A. aomoriensis, parameters controlling Mg/Ca and Sr/Ca ratios of Ammonia aomoriensis were investigated. Under constant seawater chemistry, temperature dominates the magnesium incorporation into A. aomoriensis test by an exponential increase of 5.1% per °C (Mg/Ca = 1.0980 (±0.2073) e0.0510 (±0.0097) T; Mg/Ca = 0.5565 (±0.3897) + 0.1279 (±0.0242) T, 2.4–24 °C including field samples). Whereas, temperature has no significant effect on Strontium uptake. Calcite Sr/Ca of A. aomoriensis is primarily explained by Mg/Ca value (~3% per mmol/mol). Salinity variations are of subordinate importance for both Mg and Sr content in the test of A. aomoriensis, Mg/Ca raises linearly with approximately 2% per salinity unit, and Sr/Ca increases ~1% per salinity unit. Importantly, biological mechanism might be an inestimable factor perturbing Mg and Sr response to environmental parameters in natural waters, complicating the paleoclimate reconstruction.

A near-infrared light triggered photothermal H2S-release platform was developed using a combination of photothermal nanoparticles and thermo-labile precursors, and was exploited for synchronous photothermal stimulation and gas release to suppress cell viability. Polyethyleneimine-dithiocarbamate as a H2S donor was assembled on reduced graphene oxide (rGO) nanosheets by electrostatic adsorption. In the nanocomposites, rGO nanosheets converted near-infrared light into thermal energy and activated the H2S donor to produce H2S. Synchronous photothermal stimulation and H2S gas release resulted in effective killing of cancer cells. This work presents an effective method that suppresses the growth of tumour cells and leads to an improved anti-cell proliferation outcome. Near-infrared light-triggered photothermal stimulation, in combination with H2S gas generation, may offer an effective strategy to further develop a cancer synergistic treatment platform.

The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cultured at different temperatures (6, 12, and 18°C) and salinities (15, 20, 25, and 30 psu) for 10 weeks. In total, 2616 living (stained) specimens were obtained and analyzed. Foraminiferal abundance ranged from 9 to 202 individuals/ 10 g wet weight of sediment. The highest abundance was obtained at 12°C, 25 psu and the lowest at 6°C, 15 psu. Statistical results demonstrated that temperature affected foraminiferal community more significantly than salinity. Most foraminiferal community parameters (abundance, species richness, Margalef index, and Shannon-Wiener diversity) were significantly positively correlated to temperature, but not to salinity, whereas Pielou’s evenness was significantly negatively correlated to both temperature and salinity. The interactive effect of temperature and salinity on foraminiferal abundance was significant. In addition, with increasing temperature, the species composition shifted from hyaline Rotaliida to porcellaneous Miliolida. The abundance of dominant species (e.g., Ammonia aomoriensis , A. beccarii , and Quinqueloculina seminula ) showed significant positive correlations to temperature. Our study indicated that the intertidal foraminiferal community responds sensitively and rapidly to the changes of salinity and, especially, temperature by shifting foraminiferal species composition and altering the community parameters.

For the first time it is demonstrated that sulfhydryl compounds can suppress longitudinal etching of gold nanorods via consuming oxidizers, which provides a new signaling mechanism for colorimetric sensing. As a proof of concept, a colorimetric assay is developed for detecting organophosphorus pesticides, which are most widely used in modern agriculture to improve food production but with high toxicity to animals and the ecological environment. Triazophos was selected as a model organophosphorus pesticide. In the absence of triazophos, the active acetylcholinesterase can catalyze the conversion of acetylthiocholine iodide to thiocholine whose thiol group can suppress the I2-induced etching of gold nanorods. When triazophos is present, the activity of AchE is inhibited, and I2-induced etching of gold nanorods results in triazophos concentration-dependent color change from brown to blue, pink, and red. The aspect ratio of gold nanorods reduced with gradually blue-shifted longitudinal absorption. There was a linear detection range from 0 to 117 nM (R2 = 0.9908), the detection limit was 4.69 nM, and a good application potential was demonstrated by the assay of real water samples. This method will not only contribute to public monitoring of organophosphorus pesticides but also has verified a new signaling mechanism which will open up a new path to develop colorimetric detection methods.

Marine blue holes are precious geological heritages with high scientific research values. Their physical and chemical characteristics are unique because of the steep-walled structure and isolated water column which create isolated ecosystems in geographically restricted areas. The Sansha Yongle Blue Hole (SYBH) is the world’s deepest marine blue hole. Here, we generated the first DNA metabarcoding dataset from SYBH sediment focusing on foraminifera, a group of protists that have colonized various marine environments. We collected sediment samples from SYBH along a depth gradient to characterize the foraminiferal diversity and compared them with the foraminiferal diversity of the costal Jiaozhou Bay (JZB) and the abyssal Northwest Pacific Ocean (NWP). We amplified the SSU rDNA of foraminifera and sequenced them with high-throughput sequencing. The results showed that the foraminiferal assemblages in SYBH were vertically structured in response to the abiotic gradients and diversity was higher than in JZB and NWP. This study illustrates the capacity of foraminifera to colonize hostile environments and shows that blue holes are natural laboratories to explore physiological innovation associated with anoxia.

MicroRNAs (miRNAs) have been shown to be promising biomarkers for disease diagnostics and therapeutics. However, the rapid, low-cost, sensitive, and selective detection of miRNAs remains a challenge because of their characters of small size, vulnerability to degradation, low abundance, and sequence similarity. Herein, we describe an enzyme-free amplification platform, consisting of a catalytic hairpin assembly (CHA) and DNA-templated silver nanoclusters (DNA/AgNCs), for miRNA analysis. In this work, two DNA hairpins (H1 and H2) were first designed for target miR-21-induced CHA, and then the fluorescence of DNA/AgNCs was quenched by BHQ1 to construct an activatable probe (AP). In the presence of target miR-21, hairpin H1 was opened by miR-21 through a hybridization reaction, and hairpin H2 was then opened by H1. During this process, miR-21 was released from H1 and participated in the next round of hybridization, triggering the CHA cycle reaction. The obtained H1-H2 products with sticky ends could react with the AP, forcing BHQ1 away from the DNA/AgNCs and thus causing the fluorescence recovery of the DNA/AgNCs. The assay for miR-21 detection demonstrated an excellent linear response to concentrations varying from 200 pM to 20 nM with the detection limit of 200 pM. The simple and cost-effective strategy holds great potential for application in biomedical research and clinical diagnostics.

The Au-S bond is the classic way to functionalize gold nanoparticles (AuNPs). However, cleavage of the bond by biothiols and other chemicals is a long-standing problem hindering practical applications, especially in cells. Instead of replacing the thiol by a carbene or selenol for stronger adsorption, it is now shown that the Pt-S bond is much more stable, fully avoiding cleavage by biothiols. AuNPs were deposited with a thin layer of platinum, and an AuNP@Pt-S nanoflare was constructed to detect the miRNA-21 microRNA in living cells. This design retained the optical and cellular uptake properties of DNA-functionalized AuNPs, while showing high-fidelity signaling. It discriminated target cancer cells even in a mixed-cell culture system, where the Au-S based nanoflare was less sensitive. Compared to previous methods of changing the ligand chemistry, coating a Pt shell is more accessible, and previously developed methods for AuNPs can be directly adapted.

For the first time it is demonstrated that sulfhydryl compounds can suppress longitudinal etching of gold nanorods via consuming oxidizers, which provides a new signaling mechanism for colorimetric sensing. As a proof of concept, a colorimetric assay is developed for detecting organophosphorus pesticides, which are most widely used in modern agriculture to improve food production but with high toxicity to animals and the ecological environment. Triazophos was selected as a model organophosphorus pesticide. In the absence of triazophos, the active acetylcholinesterase can catalyze the conversion of acetylthiocholine iodide to thiocholine whose thiol group can suppress the I