A Light-powered single-stranded DNA molecular motor with colour-selective single-step control.

To-down control of small motion is possible through top-down controlled molecular motors in replacement of larger actuators like MEMS or NEMS (micro- or nano-electromechanical systems) in the current precision technology. Improving top-down control of molecular motors to every single step is desirable for this purpose, and also for synchronization of motor actions for amplified effects. Here we report a designed single-stranded DNA molecular motor powered by alternated ultraviolet and visible light for processive track-walking, with the two light colours each locking the motor in a full directional step to allow saturated driving but no overstepping. This novel nano-optomechanical driving mechanism pushes the top-down control of molecular motors down to every single step, thus providing a key technical capability to advance the molecular motor-based precision technology and also motor synchronization for amplified effects.

Organic-mineral colloids regulate the migration and fractionation of rare earth elements in groundwater systems impacted by ion-adsorption deposits mining in South China.

Ion-adsorption rare earth element (REE) deposits distributed in the subtropics provide a rich global source of REEs, but in situ injection of REEs extractant into the mine can result in leachate being leaked into the surrounding groundwater systems. Due to the lack of understanding of REE speciation distribution, particularly colloidal characteristics in a mining area, the risks of REEs migration caused by in situ leaching of ion-adsorption REE deposits has not been concerned. Here, ultrafiltration and asymmetric flow field-flow fractionation coupled with inductively coupled plasma mass spectrometry (AF4-ICP-MS) were integrated to characterize the size and composition of REEs in leachate and groundwater from mining catchments in South China. Results show that REEs were associated with four fractions: 1) the <1 kDa fraction including dissolved REEs; 2) the 1 - 100 kDa nano-colloidal fraction containing organic compounds; 3) the 100 kDa - 220 nm fine colloids including organic-mineral (Fe, Mn and Al (oxy)hydroxides and clay minerals); 4) the >220 nm coarse colloids and acid soluble particles (ASPs) comprising minerals. Influenced by the ion exchange effect of in situ leaching, REEs in leachate were mostly dissolved (79 %). The pH of the groundwater far from the mine site was increased (5.8 - 7.3), the fine organic-mineral colloids (46 % - 80 %) were the main vectors of transport for REEs. Further analysis by AF4 revealed that the fine colloids can be divided into mineral-rich (F1, 100 kDa - 120 nm) and organic matter-rich (F2, 120 - 220 nm) populations. The main colloids associated with REEs shifted from F1 (64 % ∼ 76 %) to F2 (50 % ∼ 52 %) away from the mining area. For F1 and F2, the metal/C molar ratio decreased away from the mining area and middle to heavy REE enrichment was presented. According to the REE fractionation, organic matter was the predominant component capable of binding REEs in fine colloids. Overall, our results indicate that REEs in the groundwater system shifted from the dissolved to the colloidal phase in a catchment affected by in situ leaching, and organic-mineral colloids play an important role in facilitating the migration of REEs.

Tracking Ion Transport in Nanochannels via Transient Single-Particle Imaging.

The transport behavior of ions in the nanopores has an important impact on the performance of the electrochemical devices. Although the classical Transmission-Line (TL) model has long been used to describe ion transport in pores, the boundary conditions for the applicability of the TL model remain controversial. Here, we investigated the transport kinetics of different ions, within nanochannels of different lengths, by using transient single-particle imaging with temporal resolution up to microseconds. We found that the ion transport kinetics within short nanochannels may deviate significantly from the TL model. The reason is that the ion transport under nanoconfinement is composed of multi basic stages, and the kinetics differ much under different stage domination. With the shortening of nanochannels, the electrical double layer (EDL) formation would become the "rate-determining step" and dominate the apparent ion kinetics. Our results imply that using the TL model directly and treating the in-pore mobility as an unchanged parameter to estimate the ion transport kinetics in short nanopores/nanochannels may lead to orders of magnitude bias. These findings may advance the understanding of the nanoconfined ion transport and promote the related applications.

Autonomous DNA molecular motor tailor-designed to navigate DNA origami surface for fast complex motion and advanced nanorobotics.

Nanorobots powered by designed DNA molecular motors on DNA origami platforms are vigorously pursued but still short of fully autonomous and sustainable operation, as the reported systems rely on manually operated or autonomous but bridge-burning molecular motors. Expanding DNA nanorobotics requires origami-based autonomous non-bridge-burning motors, but such advanced artificial molecular motors are rare, and their integration with DNA origami remains a challenge. Here, we report an autonomous non-bridge-burning DNA motor tailor-designed for a triangle DNA origami substrate. This is a translational bipedal molecular motor but demonstrates effective translocation on both straight and curved segments of a self-closed circular track on the origami, including sharp ~90° turns by a single hand-over-hand step. The motor is highly directional and attains a record-high speed among the autonomous artificial molecular motors reported to date. The resultant DNA motor-origami system, with its complex translational-rotational motion and big nanorobotic capacity, potentially offers a self-contained "seed" nanorobotic platform to automate or scale up many applications.

A light-operated integrated DNA walker-origami system beyond bridge burning.

Integrating rationally designed DNA molecular walkers and DNA origami platforms is a promising route towards advanced nano-robotics of diverse functions. Unleashing the full potential in this direction requires DNA walker-origami systems beyond the present simplistic bridge-burning designs for automated repeatable operation and scalable nano-robotic functions. Here we report such a DNA walker-origami system integrating an advanced light-powered DNA bipedal walker and a ∼170 nm-long rod-like DNA origami platform. This light-powered walker is fully qualified as a genuine translational molecular motor, and relies entirely on pure mechanical effects that are complicated by the origami surface but must be preserved for the walker's proper operation. This is made possible by tailor-designing the origami for optimal match with the walker to best preserve its core mechanics. A new fluorescence method is combined with site-controlled motility experiments to yield distinct and reliable signals for the walker's self-directed and processive motion despite origami-complicated fluorophore emission. The resultant integrated DNA walker-origami system provides a 'seed' system for future development of advanced light-powered DNA nano-robots (e.g., for scalable walker-automated chemical synthesis), and also truly bio-mimicking nano-muscles powered by genuine artificial translational molecular motors.

Engineering electronic structure of graphene to boost Lithium-Storage performances.

Organic functionalization of graphene framework was an effective means used to boost the storage performances of lithium, but it lacked a universal strategic guideline for introducing functional groups (electron-withdrawing and electron-donating modules are overall classified). It mainly entailed designing and synthesizing graphene derivatives, in which the interference functional groups were necessarily excluded. To this end, a unique synthetic methodology based on graphite reduction cascaded by electrophilic reaction was developed. The electron-withdrawing-type groups (Br; trifluoroacetyl: TFAc) and electron-donating-type counterparts (butyl: Bu; 4-methoxyphenyl: 4-MeOPh) were readily attached to graphene sheets at a comparable functionalization degree. As the electron density of carbon skeleton was enriched by electron-donating modules, particularly for Bu units, the lithium-storage capacity, rate capability and cyclability were appreciably boosted. For example, they had 512 and 286 mA h g-1 at 0.5C and 2C, respectively; and 88 % of capacity retention after 500 cycles at 1C.

Periodic Distributions and Ultrafast Dynamics of Hot Electrons in Plasmonic Resonators.

Understanding and managing hot electrons in metals are of fundamental and practical interest in plasmonic studies and applications. A major challenge for the development of hot electron devices requires the efficient and controllable generation of long-lived hot electrons so that they can be harnessed effectively before relaxation. Here, we report the ultrafast spatiotemporal evolution of hot electrons in plasmonic resonators. Using femtosecond-resolution interferometric imaging, we show the unique periodic distributions of hot electrons due to standing plasmonic waves. In particular, this distribution can be flexibly tuned by the size, shape, and dimension of the resonator. We also demonstrate that the hot electron lifetimes are substantially prolonged at hot spots. This appealing effect is interpreted as a result of the locally concentrated energy density at the antinodes in standing hot electron waves. These results could be useful to control the distributions and lifetimes of hot electrons in plasmonic devices for targeted optoelectronic applications.

Visible-light induced three-component reaction for α-aminobutyronitrile synthesis by C-C bond formation using quantum dots as photocatalysts.

We describe a three-component reaction of malononitrile, benzaldehyde and N,N-dimethylaniline using aluminium doped CdSeS/CdZnSeS(Al)/ZnS quantum dots (QDs) as visible light catalysts to synthesize α-aminobutyrilitriles at room temperature and under mild conditions. The reactions exhibit high functional group tolerance, and the well dispersed quantum dot catalysts are highly efficient with a turnover number (TON) greater than 1.1 × 103 and can be recycled at least three times without significant loss of catalytic activity.

Glucocorticoids combined with tofacitinib in the treatment of Castleman's disease: A case report.

BACKGROUND: Castleman's disease (CD), also known as vascular follicular lymphadenopathy is a rare proliferative disease of lymphoid tissue of unknown etiology that is clinically classified as unicentric CD (UCD) or multicentric CD (MCD) depending on lymph node involvement. At present, idiopathic MCD (iMCD) is treated with interleukin-6 inhibitors, but some patients have poor clinical outcomes. This paper reports on a case of iMCD that achieved a good therapeutic effect after treatment with glucocorticoids combined with tofacitinib. The relevant data are summarized and reported below. CASE SUMMARY: This paper reports on a case of MCD in a 49-year-old female with persistent peritoneal effusion as the first manifestation and combined with multiple lymphadenopathies. Lymph node biopsy showed Castleman's disease-like changes. The ascites subsided after treatment with glucocorticoids and tofacitinib, indicating that the treatment was effective. CONCLUSION: The combination of glucocorticoids with tofacitinib is an effective regimen for the treatment of CD.

Retraction Notice to: Elevated Tristetraprolin Impairs Trophoblast Invasion in Women with Recurrent Miscarriage by Destabilization of HOTAIR.

[This retracts the article DOI: 10.1016/j.omtn.2018.07.001.].

A high-fidelity light-powered nanomotor from a chemically fueled counterpart via site-specific optomechanical fuel control.

Optically powered nanomotors are advantageous for clean nanotechnology over chemically fuelled nanomotors. The two motor types are further bounded by different physical principles. Despite the gap, we show here that an optically powered DNA bipedal nanomotor is readily created from a high-performing chemically fuelled counterpart by subjecting its fuel to cyclic site-specific optomechanical control - as if the fuel is optically recharged. Optimizing azobenzene-based control of the original nucleotide fuel selects a light-responsive fuel analog that replicates the different binding affinity of the fuel and reaction products. The resultant motor largely retains high-performing features of the original chemical motor, and achieves the highest directional fidelity among reported light-driven DNA nanomotors. This study thus demonstrates a novel strategy for transforming chemical nanomotors to optical ones for clean nanotechnology. The strategy is potentially applicable to many chemical nanomotors with oligomeric fuels like nucleotides, peptides and synthetic polymers, leading to a new class of light-powered nanomotors that are akin to chemical nanomotors and benefit from their generally high efficiency mechanistically. The motor from this study also provides a rare model system for studying the subtle boundary between chemical and optical nanomotors - a topic pertinent to chemomechanical and optomechanical energy conversion at the single-molecule level.

Effects of in situ leaching on the origin and migration of rare earth elements in aqueous systems of South China: Insights based on REE patterns, and Ce and Eu anomalies.

In situ leaching of ion-adsorption rare earth element (REE) deposits has released large amounts of REE-containing wastewater. However, the origin, speciation, distribution and migration of REEs in aqueous systems of the mining catchment are poorly understood. Groundwater, surface water, in situ leachates and weathered granite soil samples were collected from a catchment affected by mining activities in South China. The REE concentrations in groundwater (6.18 × 10-3-0.49 µmol L-1) and surface water (2.54-44.05 µmol L-1) decreased from upstream to downstream. REEs in groundwater were detected in organic matter associated (FA-REE) colloids, while the REE3+ and REE(SO4)+ were converted to REE(CO3)+ and FA-REE colloids from leachates and upstream surface water to downstream. The REE patterns of leachates and upstream groundwater (light and middle REE enrichment) resembled those of soil, but showed heavy REE enrichment due to FA-REE colloids in the downstream. REE in surface water were derived from middle REE enriched leachate. The Ce and Eu anomalies in the water samples indicated the REE origin (i.e., mining activities) and the hydrological variations (e.g., oxidation environment and water-rock interaction). Our results reveal the origin and fate of REE in aqueous systems of ion-adsorption REE mining catchments.

SPRY4 regulates trophoblast proliferation and apoptosis via regulating IFN-γ-induced STAT1 expression and activation in recurrent miscarriage.

PROBLEM: The dysregulation of trophoblast functions is one of the leading causes of recurrent miscarriage (RM), which frustrates 1%-5% of couples of childbearing ages. Sprouty 4 (SPRY4) is considered as a tumour suppressor and exerts a negative role in cell viability. However, its role in regulating trophoblast behaviors at the maternal-fetal interface remains largely unknown. METHOD OF STUDY: First-trimester villous samples were collected from RM patients and healthy controls (HCs) to determine the SPRY4 expression in human placenta during early pregnancy. The HTR8/SVneo cell line was introduced to clarify trophoblast cell functions via transfecting with specific short interfering RNA against SPRY4 or SPRY4-overexpressing lentivirus in vitro. In addition, gene expression microarray analysis was performed to explore the downstream molecules and pathways. RESULTS: Our results revealed that SPRY4 expression was significantly increased in the first-trimester cytotrophoblasts of RM patients compared with HCs. Furthermore, SPRY4 overexpression inhibited trophoblast proliferation and accelerated apoptosis in vitro, while SPRY4 knockdown reversed these effects. Mechanistically, IFN-γ -induced STAT1 expression and activation were involved in the regulation of trophoblast proliferation and apoptosis by SPRY4, and IFN-γ promoted SPRY4 expression and STAT1 phosphorylation through PI3K/AKT pathway. Additionally, both STAT1 and phosphorylated STAT (p-STAT) levels were also upregulated in trophoblasts from RM patients and positively correlated with SPRY4 expression. CONCLUSION: Our findings indicate that SPRY4 may act as a negative regulator of trophoblast functions through upregulating IFN-γ/PI3K/AKT-induced STAT1 activation. High levels of SPRY4 and STAT1 may contribute to RM development and progression, and blocking of either target could be a novel therapeutic strategy for RM patients.

PDL1 blockage increases fetal resorption and Tfr cells but does not affect Tfh/Tfr ratio and B-cell maturation during allogeneic pregnancy.

A successful pregnancy requires sophisticated regulation of uterine microenvironment to guarantee the existence of semi-allogeneic conceptus without immune rejection. T follicular regulatory (Tfr) cells exert a suppressive effect on Tfh-cell expansion, B-cell response, and antibody production. Although accumulating evidence has demonstrated that dysregulations of Tfr cells can bring on various immunological diseases, their immunomodulatory roles during pregnancy still remain unheeded. Herein, we introduced an allogeneic normal-pregnant mouse model and found that CD4+CXCR5hiPD-1hiFoxp3+ Tfr cells were preferentially accumulated in the uterus at mid-gestation and displayed a distinct phenotype. In addition, the absence of PDL1 resulted in increased fetal resorption by favoring Tfr cells accumulation and upregulating PD-1 expression on these cells. However, PDL1 blockade affected neither the ratio of Tfh/Tfr cells nor the maturation and differentiation of B cells. Overall, our results are the first to present a correlation of Tfr cells accumulation with healthy allogeneic pregnancy and PDL1 blockade-induced miscarriage, and to indicate that appropriate assembly of Tfr cells is important for pregnancy maintenance. Since blockade of PD-1-PDL1 pathway leads to more Tfr cells and fetal losses, the reproductive safety must be taken into consideration when PD-1/PD-L1 checkpoint blockade immunotherapy is used in pregnancy.

Novel D-A-D-Type Supramolecular Aggregates with High Photoelectric Activity for Construction of Ultrasensitive Photoelectrochemical Biosensor.

In this work, hydrazine-functionalized perylene diimide derivative supramolecular (HPDS), a novel self-enhanced donor-acceptor-donor (D-A-D) type aggregates with excellent photoelectric activity, was synthesized by a facile one-pot green route and further applied in construction of coreactant-free photoelectrochemical (PEC) biosensor for ultrasensitive DNA assay. Impressively, the HPDS formed by D-A-D units not only possessed effectively shorted electron-transfer path between donor and acceptor, but also presented a desiring aggregate state via the π-π stacking of perylene core and hydrogen bonding of the terminal moiety, thereby acquiring a high density electron flow for generating the extremely high PEC signal. Experimental data showed that the well film-formed HPDS aggregate could produce an exciting photocurrent intensity about 6-fold stronger than that of precursor perylene dianhydride with donor N2H4 in detection buffer and even 12-fold than that of perylene dianhydride only. In this respect, the resultant HPDS aggregate as a novel self-enhanced PEC signal tag was adopted to fabricate the coreactant-free PEC biosensor with the help of target dual-recycling-induced bipedal DNA walker cascade amplification strategy for ultrasensitive DNA (a fragment of TP53 gene) assay. The proposed biosensor showed a high sensitivity with a low detection limit down to femtomole level, providing a new avenue for sensitive bioanalysis and clinical diagnosis.

Photosensitive Tin Sulfur Dioxide Complexes with Unexpected Bonding Modes.

Infrared spectra of the matrix-isolated Sn(η2 -O2 S), Sn(η2 -OSO), Sn(η2 -O2 S)(η1 -OSO), Sn(η2 -O2 S)2, OSn2 (η2 -SO), and Sn(µ2 -O2 )SnS molecules were observed following laser-ablated Sn atom reactions with SO2 during condensation in solid argon. The assignments for the major vibrational modes were confirmed by appropriate S18 O2 and 34 SO2 isotopic shifts and density functional vibrational frequency calculations (B3LYP and BPW91). Interestingly, the mononuclear complexes are interconvertible; that is, irradiation induces the isomerization of Sn(η2 -O2 S) and Sn(η2 -O2 S)(η1 -OSO) to Sn(η2 -OSO) and Sn(η2 -O2 S)2 , respectively, and vice versa on annealing. However, there is no evidence of isomerization reaction in between the binuclear molecules OSn2 (η2 -SO) and Sn(µ2 -O2 )SnS. Bonding in these products is discussed, and the electronic structure changes associated with different bonding types are revealed, which is crucial for the observed photochemical reactions.

EIF5A1 promotes trophoblast migration and invasion via ARAF-mediated activation of the integrin/ERK signaling pathway.

Trophoblast dysfunction is one mechanism implicated in the etiology of recurrent miscarriage (RM). Regulation of trophoblast function, however, is complex and the mechanisms contributing to dysregulation remain to be elucidated. Herein, we found EIF5A1 expression levels to be significantly decreased in cytotrophoblasts in RM villous tissues compared with healthy controls. Using the HTR-8/SVneo cell line as a model system, we found that overexpression of EIF5A1 promotes trophoblast proliferation, migration and invasion in vitro. Knockdown of EIF5A1 or inhibiting its hypusination with N1-guanyl-1,7-diaminoheptane (GC7) suppresses these activities. Similarly, mutating EIF5A1 to EIF5A1K50A to prevent hypusination abolishes its effects on proliferation, migration and invasion. Furthermore, upregulation of EIF5A1 increases the outgrowth of trophoblasts in a villous explant culture model, whereas knockdown has the opposite effect. Suppression of EIF5A1 hypusination also inhibits the outgrowth of trophoblasts in explants. Mechanistically, ARAF mediates the regulation of trophoblast migration and invasion by EIF5A1. Hypusinated EIF5A1 regulates the integrin/ERK signaling pathway via controlling the translation of ARAF. ARAF level is also downregulated in trophoblasts of RM villous tissues and expression of ARAF is positively correlated with EIF5A1. Together, our results suggest that EIF5A1 may be a regulator of trophoblast function at the maternal-fetal interface and low levels of EIF5A1 and ARAF may be associated with RM.

Elevated Tristetraprolin Impairs Trophoblast Invasion in Women with Recurrent Miscarriage by Destabilization of HOTAIR.

Tristetraprolin (TTP) regulates the stability of multiple targets that have important biological roles. However, the role of TTP in trophoblasts at the maternal-fetal interface remains poorly understood. We demonstrated that TTP was upregulated in placental trophoblasts from patients with recurrent miscarriages (RMs). Immunofluorescence and immunoblotting analyses indicated that TTP was redistributed from the nucleus to the cytoplasm in trophoblasts from patients with RMs. Trophoblast invasion and proliferation was repressed by TTP overexpression and was enhanced by TTP knockdown. Interestingly, TTP knockdown promoted trophoblast invasion in an ex vivo explant culture model. Furthermore, TTP overexpression in trophoblasts significantly inhibited the expression of the long non-coding RNA (lncRNA) HOTAIR. TTP was found to regulate HOTAIR expression by a posttranscriptional mechanism. To RNA immunoprecipitation (RIP) and RNA-protein, pull-down identified TTP as a specific binding partner that decreased the half-life of HOTAIR and lowered steady-state HOTAIR expression levels, indicating a novel posttranscriptional regulatory mechanism. Our findings identify a novel function for TTP in lncRNA regulation and provide important insights into the regulation of lncRNA expression. This study reveals a new pathway governing the regulation of TTP/HOTAIR in trophoblast cell invasion during early pregnancy.

Deep Surveying of the Transcriptional and Alternative Splicing Signatures for Decidual CD8+ T Cells at the First Trimester of Human Healthy Pregnancy.

Decidual CD8+ (dCD8) T cells have been proposed to play important roles in immune protection against the invading pathogens and in tolerance toward the growing semi-allogeneic fetus during early pregnancy. However, their phenotypic and functional characteristics remain poorly defined. Here, we performed the first analysis of the transcriptional and alternative splicing (AS) signatures for human first-trimester dCD8 T cells using high-throughput mRNA sequencing. Our data revealed that dCD8 T cells have distinct transcriptional and AS landscapes when compared with their autologous peripheral blood CD8+ (pCD8) T counterparts. Furthermore, human dCD8 T cells were observed to contain CD8-Treg and effector-memory T-cell subsets, and display enhanced functionality in terms of degranulation and cytokine production on a per-cell basis. Additionally, we have identified the novel splice junctions that use a high ratio of the non-canonical splicing motif GC-AG and found that AS is not a major contributor to the gene expression-level changes between paired pCD8 and dCD8 T cells. Together, our findings not only provide a comprehensive framework of the transcriptional and AS landscapes but also reveal the functional feature of human dCD8 T cells, which are of great importance in understanding the biology of these cells and the physiology of human healthy pregnancy.