One-Step to Prepare Lignin Based Fluorescent Nanoparticles with Excellent Radical Scavenging Activity

Fluorescent nanomaterials have attracted much attention,due to their unique luminescent properties and promis-ing applications in biomedical areas.In this study,lignin basedfluorescent nanoparticles(LFNP)with high yield(up to 32.4%)were prepared from lignin nanoparticles(LNP)by one-pot hydrothermal method with ethylene-diamine(EDA)and citric acid.Morphology and chemical structure of LFNP were investigated by SEM,FT-IR,and zeta potential,and it was found that the structure of LFNP changed with the increase of citric acid addition.LFNP showed the highestfluorescence intensity under UV excitation at wavelengths of 375–385 nm,with emis-sion wavelengths between 454–465 nm,and exhibited strong photoluminescence behavior.Meanwhile,with the increase of citric acid content,the energy gap(ΔE)gradually decreased from 3.87 to 3.14 eV,which corresponds to the gradual enhancement offluorescence performance.LFNP also exhibited excellent antioxidant activity,with DPPH free radical scavenging rate increased from 80.8%for LNP up to 96.7%for LFNP,confirming the great potential of these materials for application in biomedicine and cosmetic health care.

Summer Warming Limited Bud Output Drives a Decline in Daughter Shoot Biomass through Reduced Photosynthetis of Parent Shoots in Leymus chinensis Seedlings

Understanding how summer warming influences the parent and daughter shoot production in a perennial clonal grass is vital for comprehending the response of grassland productivity to global warming.Here,we conducted a simulated experiment using potted Leymus chinensis,to study the relationship between the photosynthetic activ-ity of parent shoots and the production of daughter shoots under a whole(90 days)summer warming scenario(+3°C).The results showed that the biomass of parents and buds decreased by 25.52%and 33.45%,respectively,under warming conditions.The reduction in parent shoot biomass due to warming directly resulted from decreased leaf area(18.03%),chlorophyll a(18.27%),chlorophyll b(29.21%)content,as well as a reduction in net photosynthetic rate(7.32%)and the maximum quantum efficiency of photosystem II(PSII)photochemistry(4.29%).The decline in daughter shoot biomass was linked to a decrease in daughter shoot number(33.33%)by warming.However,the number of belowground buds increased by 46.43%.The results indicated that long-term summer warming reduces biomass accumulation in parent shoot by increasing both limitation of stoma and non-stoma.Consequently,the parent shoot allocates relatively more biomass to the belowground organs to maintain the survival and growth of buds.Overall,buds,as a potential aboveground population,could remedy for the cur-rent loss of parent shoot density by increasing the number of future daughter shoots if summer warming subsides.

Two Distinct Fluorescent Quantum Clusters of Gold Starting from Metallic Nanoparticles by pH-Dependent Ligand Etching

Two fl uorescent quantum clusters of gold,namely Au25 and Au8,have been synthesized from mercaptosuccinic acid-protected gold nanoparticles of 45 nm core diameter by etching with excess glutathione.While etching at pH~3 yielded Au_(25),that at pH 7-8 yielded Au_(8).This is the fi rst report of the synthesis of two quantum clusters starting from a single precursor.This simple method makes it possible to synthesize well-defined clusters in gram quantities.Since these clusters are highly fl uorescent and are highly biocompatible due to their low metallic content,they can be used for diagnostic applications.

Functional characterization of a Δ6 fatty acid desaturase gene and its 5′-upstream region cloned from the arachidonic acid-rich microalga Myrmecia incisa Reisigl(Chlorophyta)

It is suggested that Δ6 fatty acid desaturase(FAD) plays a critical role in the biosynthesis of polyunsaturated fatty acids in plants and microalgae. But why does it adapt to the changed environments such as nitrogen starvation is seldom understood. One Δ6 FAD gene( MiD6 fad) from an arachidonic acidrich microalga M yrmecia incisa Reisigl(Chlorophyta) was first heterologously expressed in S accharomyces cerevisiae for the identification of function. The fatty acid profile of transgenic yeast detected by gas chromatography-mass spectrometry illustrated that the enzyme MiD6 FAD could convert linoleic and ?-linolenic acids to γ-linolenic and stearidonic acids, respectively, demonstrating that M iD6 fad encoded a Δ6 FAD. A 1 965-bp fragment of the cloned 2 347-bp 5′-upstream region of M iD6 fad was next subcloned and fused upstream with green fluorescent protein(GFP) gene to replace the GAL1 promoter of the vector pYES2. The generated construct was transformed into S. cerevisiae for function determination. Confocal microscopic images of the transformed line illustrated that this inserted fragment could drive GFP expression, which was further verified by fluorescence intensity quantification and Western blot analysis using antiGFP antibody. The conversion efficiency(approximately 2%-3%) of MiD6 FAD was much lower than the reported ? 3 FAD and Δ6 elongase in this microalga, suggesting that MiD6 FAD catalysed the possible ratelimiting step for ArA biosynthesis. The presence of several putative c is-acting regulatory elements in this identified promoter sheds new light on the regulation mechanism research of Δ6 FAD transcription for the ArA production in M. incisa in changing environmental factors.

Characterization of dissolved organic matter in submarine groundwater from a salt marsh in Chongming Island,China

Salt marshes are research hotspots of the carbon cycle in coastal zones because large amounts of atmospheric carbon dioxide is fi xed by salt marshes vegetation and stored in its biomass and soil.Dissolved organic carbon(DOC)in submarine groundwater(well water and pore water)in salt marshes plays an important role in advective exchange between the salt marshes and coastal waters.However,the molecular characteristics of DOC in salt marsh groundwater are poorly understood because of the complex DOC structures and hydrodynamic process.In this study,fl uorescent components and refractory DOC(RDOC)in submarine groundwater from a salt marsh(Chongming Island,China)and adjacent coastal water were characterized by fl uorescence spectroscopy and nuclear magnetic resonance spectroscopy.The fl uorescent components identifi ed by parallel factor analysis indicated that humic-like substances dominated the chromophoric dissolved organic matter in the submarine groundwater.The chromophoric dissolved organic matter and dissolved organic matter in the submarine groundwater had non-conservative behaviors because of additions from terrestrial humic substances.The nuclear magnetic resonance spectra indicated that bioactive substances(carbohydrates)contributed only 13.2%-14.8%of the dissolved organic matter in the submarine groundwater but carboxyl-rich alicyclic molecules(CRAMs),the main components of RDOC,contributed 64.5%of the dissolved organic matter.Carbohydrates and CRAMs contributed 16.4%and 61.7%of the dissolved organic matter in the coastal water,similar to the contributions for submarine groundwater.The DOC concentration in submarine groundwater was 386±294μmol/L,which was signifi cantly higher than that in coastal water(91±19μmol/L).The high DOC concentrations and>60%relative RDOC content suggested that submarine groundwater may be an important source of RDOC to coastal seawater.This information will be helpful for estimating the climate eff ects of salt marsh blue carbon.

Eff ects of temperature on photosynthetic performance and nitrate reductase activity in vivo assay in Gracilariopsis lemaneiformis (Rhodophyta)

Gracilariopsis lemaneiformis is an economically-valued species and widely cultured in China at present.After being acclimated to diff erent growth temperatures(15,20,25,and 30°C)for 7 days,the relative growth rate(RGR),nitrate reductase activity,soluble protein content and chlorophyll a fl uorescence of G.lemaneiformis were examined.Results show that RGR was markedly aff ected by temperature especially at 20°C at which G.lemaneiformis exhibited the highest eff ective quantum yield of PSII[Y(II)]and lightsaturated electron transport rate(ETR max),but the lowest non-photochemical quenching.Irrespective of growth temperature,the nitrate reductase activity increased with the incubation temperature from 15 to 30°C.In addition,the greatest nitrate reductase activity was found in the thalli grown at 20°C.The value of temperature coeffi cient Q10 of alga cultured in 15°C was the greatest among those of other temperatures tested.Results indicate that the optimum temperature for nitrate reductase synthesis was relatively lower than that for nitrate reductase activity,and the relationship among growth,photosynthesis,and nitrate reductase activity showed that the optimum temperature for activity of nitrate reductase in vivo assay should be the same to the optimal growth temperature.

Comparison of the photo-acclimation potential of fl oating and benthic thalli of Sargassum horneri(Phaeophyta)during autumn and winter

Sargassum horneri is a foundational species and an important contributor to the fl oating seaweed stock along the northeastern coast of Asia.In this study,benthic and fl oating thalli of S.horneri were collected from Changdao Island(37°54′N,120°43′E),Bohai Bay,China.We conducted an in-situ and an indoor experiment to study the acclimation potential in S.horneri to abiotic conditions at sea surface in autumn and winter.Both benthic and fl oating thalli were cultured in situ for two months(from October to December)at diff erent depths:0 m above sea level(masl)and 3 m below sea level(mbsl),and their growth rate,biochemical content,and photosynthetic performance were compared.During the fi rst month of culture,the relative growth rate of fl oating thalli was 2-fold greater than that of benthic thalli at 0 masl.The photosynthetic rate of most thalli was signifi cantly higher at 0 masl than at 3 mbsl.In the indoor experiments,fl oating and benthic thalli were exposed to high light intensity(400μmol photons/(m^(2)·s)photosynthetically active radiation(PAR))for 21 d,and their photo-acclimation capacities were compared.Under high light intensity,the two types of thalli showed low maximum quantum yield(F_(v)/F_(m))and light utilisation effi ciency(α)but high light saturation point(E_(k)).Floating thalli showed higher photosynthetic rate and photoprotective ability than benthic thalli at high light intensity.The eff ective quantum yield of photosystem II[Y(II)]of both types of thalli recovered after a 6-day treatment with low light intensity(40μmol photons/(m^(2)·s)).These fi ndings suggest that S.horneri is highly acclimated to the sea surface environment,which possibly contributes to its rapid accumulation and long free-fl oating periods at the sea surface.

Morphological and phylogenetic diversity of magnetotactic bacteria and multicellular magnetotactic prokaryotes from a mangrove ecosystem in the Sanya River,South China

Magnetotactic bacteria(MTB)are morphologically and phylogenetically diverse prokaryotes commonly able to produce magnetic nanocrystals within intracellular membrane-bound organelles(i.e.,magnetosomes)and to swim along geomagnetic field lines.We studied the diversity of MTB in the samples collected from a mangrove area in the Sanya River,Hainan,South China,using microscopic and microbial phylogenetic methods.Results of microanalysis and observation in microscopy and energy dispersive X-ray spectroscopy(EDXS)reveal a highly morphological diversity of MTB including unicellular cocci,vibrios,rod-shaped bacteria,and three morphotypes of multicellular magnetotactic prokaryotes(MMPs).In addition,analysis of the 16S rRNA gene showed that these MTB were clustered into 16 operational taxonomic units affi liated to the Alpha-,Delta-,and Gamma-proteobacteria classes within the Proteobacteria phylum.Meanwhile,by using the coupled fluorescence and transmission electron microscopy analysis,rodshaped bacteria,vibrio,and cocci were phylogenetically and structurally identified at the single-cell level.This study demonstrated highly diverse MTB communities in the mangrove ecosystem and provide a new insight into the overall diversity of MTB.

Application of super-resolution fluorescence microscopy in hematologic malignancies

Hematologic malignancies are one of the most common malignant tumors caused by the clonal proliferation and differentiation of hematopoietic and lymphoid stem cells.The examination of bone marrow cells combined with immunodeficiency typing is of great significance to the diagnostic type,treatment and prognosis of hematologic malignancies.Super-resolution fluorescence microscopy(SRM)is a special kind of optical microscopy technology,which breaks the resolution limit and was awarded the Nobel Prize in Chemistry in 2014.With the development of SRM,many related technologies have been applied to the diagnosis and treatment of clinical diseases.It was reported that a major type of SRM technique,single molecule localization microscopy(SMLM),is more sensitive than flow cytometry(FC)in detecting cell membrane antigens'expression,thus enabling better chances in detecting antigens on hematopoietic cells than traditional analytic tools.Furthermore,SRM may be applied to clinical pathology and may guide precision medicine and personalized medicine for clone hematopoietic cell diseases.In this paper,we mainly discuss the application of SRM in clone hematological malignancies.

PSI-driven cyclic electron fl ow partially alleviates the peroxidation of red alga Gelidium amansii(Gelidiaceae)caused by temporary high temperature

PSI-driven cyclic electron fl ow(CEF-I)helps higher plants avoid severe heat damage.Gelidium amansii,a red seaweed used in the production of agar,inhabits subtidal rocks but can be found in the intertidal zone.The biological role of CEF-I is still unclear in this organism.Wild G.amansii was exposed to 30℃heat stress for 12 h with continuous lighting.The results showed that treatment at 30℃gradually decreased maximal PSII photochemical effi ciency(F_(v)/F_(m)),linear electron transfer rate,and activity of photosynthetic reaction center.Both the maximal photochemical effi ciency under light(F_(v)'/F_(m)')and maximum quantum yield of light-adapted PSII(Φ_(PSII))were maintained at a relatively stable level during the initial 6 h and then signifi cantly decreased at 12 h.The up-regulated CEF-I helps to enhance proton gradient transfer across thylakoid membrane to protect oxygen-evolving complex against heat damage.Following the addition of a CEF-I inhibitor to plants,the F_(v)/F m greatly decreased,suggesting that the CEF-I alleviates degree of photoinhibition caused by strong light.The results of measurement of antioxidant enzymes,including superoxide dismutase(SOD),ascorbate peroxidase(APX)and catalase(CAT),and the contents of H_(2)O_(2)and malonaldehyde(MDA)provided additional evidence that CEF-I plays a protective role to a certain extent for G.amansii to manage stress at 30℃.Therefore,it can be concluded that CEF-I enables G.amansii to survive in intertidal zones by protecting it from the heat damage caused by high temperature stress.

Recent Progress in Endoplasmic Reticulum-Targetable Small-Molecule Probes for Fluorescence Sensing and Phototherapy

The endoplasmic reticulum(ER)is the most widespread organelle within eukaryotic cells,performing various essential functions such as protein synthesis,post-translational modifications,and lipid metabolism.Abnormal fluctuations of biologically active species and microenvironments in the ER can disrupt homeostasis and eventually lead to ER stress,which is closely linked to the occurrence and progression of many human diseases.Therefore,the ER has been regarded as an important analytical object as well as a promising therapeutic target in both bio sensing and biomedicine.Recently,there has been a growing interest in developing photon-excited molecular tools to uncover the physio pathological roles of ER and treat ERrelated disorders.This review presents a comprehensive summary of recent advances in ER-targeted small-molecule probes and their applications for fluorescent sensing and phototherapy,mainly focusing on targeting strategies and probe design principles.Last,we discuss the challenges involved with ER-targeted probes and highlight potential prospects in this field.

High-efficiency thermally activated delayed fluorescence materials via a shamrock-shaped design strategy to enable OLEDs with external quantum efficiency over 38%

To achieve highly-efficient organic light-emitting diodes(OLEDs),great efforts have been devoted into constructing thermally activated delayed fluorescence(TADF)with high horizontal dipole ratios(Θ//).Here,we proposed a design strategy by integrating a rigid electron-accepting oxygen-bridged boron core with triple electron-donating groups,which exhibited a“shamrock-shape”,namely BO-3DMAC and BO-3DPAC.Benefiting from the rigid and large-planar skeletons brought by shamrock-shaped design,BO-3DMAC and BO-3DPAC exhibit highΘ//of 84%/70%and 93%/94%in neat/doped films,respectively,and finally furnish excellent external quantum efficiencies(EQEs)of up to 28.3%and 38.7%in 20 wt%doped OLEDs with sky-blue emission,as well as adequate EQEs of up to 21.0%and 16.7%in nondoped OLEDs.This work unveils a promising strategy to establish high-Θ//TADF emitters by constructing large-planar molecular structures using shamrock-shaped design.

Overcoming power efficiency limitation of white fluorescence light-emitting diodes via multilevel-hydrogen-bond matrix

High power efficiency and low efficiency roll-off at practical luminance are two requirements for new-generation energy-saving lighting technologies,which are still bottlenecks of thermally activated delayed fluorescence(TADF)white organic light-emitting diodes(WOLED),despite the advantages of TADF materials and devices in low cost and high sustainability.Herein,we developed a spiro phosphine oxide host named SSOXSPO,which can form multiple and multidirectional intermolecular hydrogen bonds(IHB).The resulted multilevel IHB network integrates long-range ordered and short-range disordered alignments for suppressing triplet-polaron quenching(TPQ)and triplet-triplet annihilation(TTA).Electronic characteristics of SSOXSPO matrix are further regulated,leading to the optimal exciton allocation through balancing energy and charge transfer.As consequence,using SSOXSPO as host,the single-emissive-layer TADF WOLEDs realized the record performance,including ultralow operation voltage as∼4.0 V,power efficiency beyond fluorescent tube(70.1 lm W−1)and negligible external quantum efficiency roll-off(3%)at 1000 nits for indoor lighting.This work demonstrates that multiple interplays supported by host matrixes in TADF WOLEDs can facilitate the synergistic effects of TADF emitters on 100%exciton utilization.

A versatile tool for tracking the differentiation of human embryonic stem cells

The ability of human embryonic stem cells(hESCs)to undergo indefinite self-renewal in vitro and to produce lineages derived from all three embryonic germ layers both in vitro and in vivo makes such cells extremely valuable in both clinical and research settings.However,the generation of specialized cell lineages from a mixture of differentiated hESCs remains technically difficult.Tissue specific promoter-driven reporter genes are power-ful tools for tracking cell types of interest in differentiated cell populations.Here,we describe the construction of modular lentivectors containing different tissue-specific promoters(Tα1 ofα-tubulin;aP2 of adipocyte Protein 2;and AFP of alpha fetoprotein)driving expression of humanized Renilla greenfluorescent protein(hrGFP).To this end,we used MultiSite gateway technology and employed the novel vectors to successfully monitor hESC differentiation.We present a versatile method permitting target cells to be traced.Our system will facilitate research in developmental biology,transplantation,and in vivo stem cell tracking.

Frontier luminous strategy of functional silica nanohybrids in sensing and bioimaging:From ACQ to AIE

Fluorescent silica organic-inorganic nanohybrids which combine designable luminescence performance of organic fluorescent dyes and various outstanding advantages of silica nanomaterials have attracted increasing research interests in these fascinating areas.Optical transparency and facile functional modification properties of silica material provide great opportunities to integrate desired fluorescent molecules for various frontier luminous applications.However,conventional organic dyes are typically subject to aggregation-caused quenching due to their aggregation in silica matrix,which could be detrimental for their performance in sensing and biomedical applications.The appearance of aggregation-induced emission luminogens(AIEgens)paves a new way for developing highly efficient fluorescent silica nanohybrids(FSNs).FSNs with intensive luminescence could be obtained due to the formation of aggregates and the restricted intramolecular motion of AIEgens in silica inorganic matrix.In this review,the reported fabrication methodologies of various FSNs based on colloidal silica nanoparticles(SNs)and mesoporous SNs including physical entrapment and covalent strategies are summarized.Especially,the AIEgens-functionalized silica hybrid nanomaterials are introduced in detail.Furthermore,chemical sensing,biosensing,and bioimaging applications of resultant FSNs are also discussed.

Core Shell Au Ag Nanoparticles in Dielectric Nanocomposites with Plasmon-Enhanced Fluorescence: A New Paradigm in Antimony Glasses

The nano era demands the synthesis of new nanostructured materials,if possible by simplified techniques,with remarkable properties and versatile applications.Here,we demonstrate a new single-step reproducible melt-quench methodology to fabricate core-shell bimetallic(Au0 Ag0)nanoparticles(2889 nm)embedded glasses(dielectrics)by the use of a new reducing glass matrix,K_(2)O B_(2)O_(3) Sb_(2)O_(3)(KBS)without applying any external reducing agent or multiple processing steps.The surface plasmon resonance(SPR)band of these nanocomposites embedded in KBS glass is tunable in the range 554-681 nm.More remarkably,taking advantage of the selective reduction capability of Sb_(2)O_(3),this single-step methodology is used to fabricate inter-metallic:rare-earth ions co-embedded(AuAg:Sm^(3+))dielectric(glass)-based-dnanocomposites and study the effect of enhanced local fi eld on the red upconversion fl uorescence of Sm^(3+)ions at 636 nm.The enhancement is found to be about 2 folds.This single-step in-situ selective reduction approach can be used to fabricate a variety of hybrid-nanocomposite devices for laser based applications(see supplementary information).

Mesogens with aggregation-induced emission properties: Materials with a bright future

Within the past two decades,chromophores,which show aggregation-induced emission(AIE),have gained considerable attention with respect to the development of luminescent liquid crystals.In contrast to common luminogens,AIE emitters do not suffer from aggregation-caused quenching of the emission in the solid state.In this review,we summarize the recent development in the field of AIE-active liquid crystals and show first model devices,which already prove the application potential of these materials.Currently,three different approaches are followed,to get access to luminescent liquid crystals––namely the synthetic approach yielding luminescent mesogens,the doping approach,and the supramolecular approach,which will be described and discussed in detail in this review.

Synthesis and properties of tetrathiafulvalene-porphyrin assemblies

Two donor-σ-acceptor molecular systems incorporating tetrathiafulvalene(TTF)and tetraphenylpor-phyrin(TPP)units,TTF-TPP(dyad 1)and TTF-TPP-TTF(triad 2),were synthesized.Both dyad 1 and triad 2 and their synthetic intermediates have been characterized by 1H nuclear magnetic resonance(1H NMR)and mass spectro-graphy(MS).Their ultraviolet and visible spectroscopy(UV-Vis)and cyclic voltammetry(CV)showed negligible intramolecular charge transfer interaction in their ground states.Theirfluorescence intensity was strongly quenched compared with TPP,which implied the photoinduced electron transfer occurred from the TTF unit to the TPP unit in the excited state.On the other hand,theirfluorescence intensity could be modulated by sequential oxidation of the TTF unit using chemical methods,which exhibited their potential application influorescence molecular switch.