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Near-infrared (NIR) phosphors play a key role in phosphor-converted NIR emitters, but to find broadband phosphors still remains a great challenge due to the lack of strategies for screening appropriate hosts. Herein, we report a broadband Sr6Sc2Al4O15:Cr3+ NIR phosphor by choosing a host that has crystallographic sites accommodated for both Ce3+ and Cr3+ simultaneously. The emission spectrum of Sr6Sc2Al4O15:Cr3+ covers the region of 600–1500 nm, having a maximum at 860 nm and a full width at half-maximum (FWHM) of 241 nm. A NIR pc-LED was fabricated by combining the Sr6Sc2Al4O15:Cr3+ phosphor with a blue LED, which can produce a NIR output power of 0.16 mW driven at 750 mA. The fabricated NIR emitter demonstrates a good suitability in night vision and non-destructive detection. [ABSTRACT FROM AUTHOR]

The abuse of pesticides has introduced a large number of residues in soil and drinking water, which can then enter the food chain and the human body. Monitoring pesticide residues and developing simple and fast detection systems for pesticide residues is urgently needed. In this study, we presented one-pot prepared CdS fluorescent quantum dots (QDs) and explored their sensing application for organic pesticides. The CdS QDs can sensitively and selectively detect three different pesticides, dichlorvos (DDVP), paraquat, and glufosinate-ammonium, through different fluorescence responses. Paraquat can effectively quench the fluorescence of the QDs and DDVP can cause remarkable fluorescent enhancement. Glufosinate-ammonium can induce both 150 nm fluorescent blueshifting and 30-fold fluorescent enhancement. The probe exhibited low detection limits for the three pesticides: 1.44 μM for paraquat, 0.23 mM for DDVP, and 49.8 μM for glufosinate-ammonium. Furthermore, based on the results, we utilized the powerful functions of smartphones to establish a concentration-gray value standard curve through RGB values and gray values to realize the qualitative detection and quantitative analysis of DDVP. It is believed that this work presents a new platform for the simultaneous detection of multiple pesticides using a single QDs probe. The present on-site method using a smartphone is of great potential for water monitoring in rural areas. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of a novel porous polymer, PS2, containing radially π-conjugated carbocycles and a linear phenylene backbone. The PS2-based membrane has a distinct small size cutoff (ca. 2.6 nm) and a major size at ∼1.5 nm for the size-selective separation of nanoparticles. [ABSTRACT FROM AUTHOR]

Neuronal cell microengineering involving micropatterning and polydimethylsiloxane (PDMS) microfluidics enables promising advances in microscale neuron control. However, a facile methodology for the precise and effective manipulation of neurons on a cell-repellent PDMS substrate remains challenging. Herein, a simple and straightforward strategy for neuronal cell patterning and neuronal network construction on PDMS based on microfluidics-assisted modification of functionalized Pluronic is described. The cell patterning process simply involves a one-step microfluidic modification and routine in vitro culture. It is demonstrated that multiple types of neuronal cell arrangements with various spatial profiles can be conveniently produced using this patterning tool. The precise control of neuronal cells with high patterning fidelity up to single cell resolution, as well as high adhesion and differentiation, is achieved too. Furthermore, neuronal network construction using the respective cell population and single cell patterning prove to be applicable. This achievement provides a convenient and feasible methodology for engineering neuronal cells on PDMS substrates, which will be useful for applications in many neuron-related microscale analytical research fields, including cell engineering, neurobiology, neuropharmacology, and neuronal sensing. [ABSTRACT FROM AUTHOR]

Iron (Fe3+) is one of the most essential elements in the human body; deficiency or overdose of Fe3+ may have adverse effects on human health and immunity. Hence, it is essential to establish a sensitive and selective method for ion detection. In this study, novel green fluorescent N-doped carbon dots (N-CDs) were prepared with caffeic acid as the carbon source via a simple hydrothermal method. The solution of the as-prepared N-CDs exhibits 21.5% quantum yield, good salt stability, excellent water solubility, low cytotoxicity and good photobleaching resistance. The N-CDs can be used as a fluorescent probe for the detection of Fe3+ ions in aqueous solutions and bioimaging in living cells. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis and characterization of a [2.2]paracyclophane-containing macrocycle (PCMC) as a new through-space conjugated macrocycle using only benzene groups as the skeleton. For comparison, a diphenylmethane-containing nanohoop macrocycle (DCMC) with a non-conjugated linker was also synthesized. Their structures were confirmed by NMR and HR-MS, and their photophysical properties were studied by UV-vis and fluorescence spectroscopies combined with theoretical calculations. The strain energy of PCMC was estimated to be as high as 72.58 kcal mol−1. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane (PDMS)-based neuron microengineering provides new opportunities for spatiotemporal control of neuronal activity and stimuli. The demand for long-lasting adhesive PDMS surfaces has steered the development of straightforward, feasible, and accessible interface modifications. Here, we describe an innovative approach for promoting and engineering neuron adhesion on a PDMS substrate based on a very simple modification using poly- D -lysine-conjugated Pluronic F127, a functionalized triblock polymer. The modification procedure only involves single-step pipetting or microfluidic-guided introduction for the reinforcement of cell adhesion in quantity, extensibility, and stability. Micropatterning at a single-cell resolution, microfluidic long-term culture, and neuron network formation were achieved. The present approach provides a previously unprecedented simple and effective technique for neuron adhesion on PDMS and may be useful for applications in neurobiology, tissue engineering, and neuronal microsystems. [ABSTRACT FROM AUTHOR]

Herein we report the precise synthesis and photophysical properties of a naphthalene-containing carbon nanohoop, cyclo[7]paraphenylene-2,6-naphthylene ([7]CPPNa2,6), as a sidewall segment of a [9,8] single-walled carbon nanotube ([9,8]SWNT) using a rationally designed strategy. To the best of our knowledge, [7]CPPNa2,6 represents the smallest chiral SWNT segment ever reported. The structure was confirmed by 1H NMR, 2D 1H–1H COSY NMR, 13C NMR, and HR-MS spectrometry. The nanohoop's interesting photophysical properties were investigated by steady-state and time-resolved spectroscopy combined with theoretical calculations. Compared with the [8]CPP and [9]CPP nanohoops, [7]CPPNa2,6 has a moderate strain energy (89.6 kcal mol−1) and a higher HOMO–LUMO gap (3.5 eV). [ABSTRACT FROM AUTHOR]

Monitoring the levels of pesticides on plant tissues is important for achieving effective protection of crops after application, as well as ensuring low levels of residues during harvest. In this study, a simple, rapid, and fieldable colorimetric method for detecting the pesticide glyphosate (Gly) on the plant tissues in situ using cysteamine-modified gold nanoparticles (AuNPs-Cys) has been developed. The aggregation of AuNPs-Cys in the presence of Gly results in a consequent color change from red to blue (or purple), which could be observed visually on the surface of plant tissues. With the naked eye, we successfully detected Gly spiked on the surface of spinach, apple, and corn leaves in situ. Further verification and quantification were achieved using surface-enhanced Raman spectroscopy (SERS) which uses AuNPs-Cys as the substrate. Moreover, application of this method was demonstrated through the evaluation of the Gly distribution on plant tissues which could greatly facilitate the development of precision agriculture technology. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AA) is a vital nutritional factor in many fruits and plants, and abnormal levels of AA are closely associated with several diseases. Therefore, the development of convenient methods for monitoring AA levels in biological systems is of great importance. In this work, we designed and synthesized three chemosensors for the rapid turn-on detection of AA via a new strategy for the azido–ascorbic acid reaction. The chemosensors were based on a 1,8-naphthalimide moiety with the azide group at different sites (probes 1, 2, and 3). The experimental results demonstrated that probe 2 showed high selectivity toward AA, having an experimental limit of detection of 74 nM. Its reduction was easier than that of probe 3 with a 3-substituted azide group. Moreover, probe 2 was successfully used for imaging of AA in garlic slice tissue for the first time. [ABSTRACT FROM AUTHOR]

As a commonly known chemical warfare agent, sulfur mustard (SM) is a severe vesicant that can induce grievous blisters on the skin and mucous membranes. Because the onset of SM toxicity is fast, a rapid, sensitive, and accurate method for the detection of SM is necessary. However, designing an effective detection method for SM is challenging because SM does not have any traditional molecular recognition sites. In this study, a fluorescence probe for the detection of SM and an SM simulant (2-chloroethyl ethyl sulfide, CEES) was developed based on the reaction of benzenemethanethiol with the analytes. A non-emissive mercaptomethylphenyl-modified tetraphenylethene (TPE) probe was designed and synthesized. This probe can emit strong fluorescence upon reacting with CEES for 5 minutes in an aqueous solution in the presence of metal ions due to the formation of a sandwich-type complex, which can effectively restrict the rotation of the phenyl rings of TPE. Furthermore, this procedure exhibited high sensitivity for analytes and can be applied to the detection of CEES in soil. As a TPE derivative, this probe also exhibited a reversible solid-state luminescence color switching between blue emission (467 nm) in the crystal state and green emission (516 nm) in the amorphous state upon fuming, grinding and heating. These results indicate that S4 has potential as a multifunctional material of a “smart” luminophor and an AIE-active fluorescent probe for SM. [ABSTRACT FROM AUTHOR]

Controllable manipulation of fluid flow is crucial for efficient particle separation, which is associated with plenty of biomedical and industrial applications. Microfluidic technologies have achieved promising progress in particle positioning depending on inertial force with or without the help of the Dean effect. Herein, we describe an inertial microfluidic system containing a spiral microchannel for various highly efficient particle separations. We demonstrated that Dean-like secondary flow can be regulated by geometric confinement in the microchannel. On the introduction of a library of micro-obstacles into the spiral microchannels, the resulting linear acceleration of secondary flow can be applied to remarkably enhance particle focusing in time and space. Further, multiple separating and sorting manipulations of particles including polymeric particles, circulating tumor cells, and blood cells, can be successfully accomplished in the dimension-confined spiral channels in a sheathless, high-throughput (typically 3 ml min−1), long-term (at least 4 h), and highly-efficient (up to 99.8% focusing) manner. The methodological achievement pointing to ease-of-use, effective, and high-throughput particle manipulations is useful for both laboratory and commercial developments of microfluidic systems in life and material sciences. [ABSTRACT FROM AUTHOR]

A novel, facile, and flexible approach for the easy assembly of microfluidic droplet devices using commercially available components is presented. Three different types of devices have been designed and tested, and the experimental results indicated that the devices offer a promising platform for the controllable generation of highly monodisperse droplets with sizes in the micrometer to millimeter diameter ranges. The advantages of the devices include their low cost, portability, reusability, high accuracy, and reliability. Most importantly, the simple and reversible combination of the different components allows the flexible design of versatile devices for fabricating multiple droplets with diverse structures. Therefore, the devices constitute a powerful microplatform that can be used for scientific and industrial applications. [ABSTRACT FROM AUTHOR]

The cellular heterogeneity of tumors has played important roles in various tumor-related research areas and applications such as the cellular biology, metastasis and clinical diagnosis of tumors. Although several microfluidics-based single-cell separation and analysis techniques have been used in research into the cellular heterogeneity of tumors, further investigation is still required for studying the effect of the biomechanical (e.g., size and deformability) heterogeneity of cells on their biological characteristics (e.g., drug resistance and tumor-initiating features). Here, we established an integrated microfluidic platform for the construction of single-cell arrays and analysis of drug resistance. Using this device, high-throughput single-cell arrays could be easily obtained according to the biomechanical (size and deformability) heterogeneity of cells. To demonstrate the capability of the microfluidic platform, a proof-of-concept experiment was implemented by determining the vincristine resistance of single glioblastoma cells with different biomechanical properties. The results indicated that the biomechanics of tumor cells had significant implications for cell drug resistance; that is, small and/or more deformable tumor cells had higher drug resistance than large and/or less deformable tumor cells. This device provides a new approach for the isolation of single cells according to the different biomechanical properties of cells. Also, it possesses practical potential for studies of tumors on a single-cell level. [ABSTRACT FROM AUTHOR]

The construction of a micro-platform capable of microscale control for continuous, dynamic, and high-throughput biomimetic tumor manipulation and analysis plays a significant role in biological and clinical research. Here, we introduce a pneumatic microstructure-based microfluidic platform for versatile three-dimensional (3D) tumor cultures. The manipulative potential of pneumatic microstructures in a fabrication-optimized microfluidic device can be stimulated to achieve ultra-repetitive (tens of thousands of times) and persistent (over several months) microfluidic control. We demonstrated that the microfluidic platform is reusable (dozens of times) for stable, reproducible, and high-throughput generation of tumors with uniform size. Various heterotypic and homotypic 3D tumor arrays can be produced successfully in the device based on robust pneumatic control. On-chip monitoring and analysis of tumor phenotypes and responses to different culture conditions and chemotherapies were also achieved in real-time in the microfluidic platform. The results indicate that fibroblasts cocultured with tumor cells positively promote the phenotypical appearance of heterotypic tumors. This microfluidic advancement offers a new methodological approach for the development of high-performance and non-disposable 3D culture systems and for tissue-mimicking cancer research. We believe that it could be valuable for various tumor-related research fields such as oncology, pharmacology, tissue engineering, and bioimaging. [ABSTRACT FROM AUTHOR]

Smart organic luminescence materials that exhibit a reversible stimuli-responsive change of luminescence color in the solid state without changing the chemical structure of their component molecules have attracted increasing interest. We employed the design strategy of introducing different weak interactions into the same molecular system to synthesize 2,7-bis(2′-methyl-[1,1′-biphenyl]-4-yl)-fluorenone (MPF). Two crystal polymorphs of MPF, green-yellow crystal G-MPF and orange crystal O-MPF, were obtained through culturing the single crystal under the different crystallization conditions of diffusing diethyl ether into its respective tetrahydrofuran or CH2Cl2 solution. Both of the two crystal polymorphs exhibit high luminous efficiency and reversible stimuli-responsive solid-state luminescence color switching. Upon heating the green crystal G-MPF or grinding the orange crystal O-MPF, their emission reversibly changes between green at 530 nm and orange at 570 nm. The X-ray single-crystal structures, characterization of the photophysical properties, powder X-ray diffraction and differential scanning calorimetry provide insight into the phase transformation and the luminescence behavior. The results indicate that the green emission of G-MPF originates from molecular J-aggregation and the orange emission of O-MPF originates from static excimers. This work discusses the relationship between the molecular stacking mode and the photophysical properties, and demonstrates a molecular design strategy to obtain stimuli-responsive organic solid-state luminescence switching materials. [ABSTRACT FROM AUTHOR]

β-BiNbO4 with a high temperature triclinic form was prepared via a high-temperature solid-state reaction ceramic method. Structural refinement and surface characteristic studies were performed. The optical absorption, and electronic calculation of the band structures and density of states were also studied. β-BiNbO4 ceramic has an indirect transition with a band energy of 3.05 eV. The valence band is dominated by O-2p states whereas the conduction band has predominantly Nb 4d and Bi 6s character. The intrinsic luminescence properties of β-BiNbO4 were reported, and present a blue emission band peak at 435 nm under the excitation of UV light. The β-BiNbO4 ceramic presents scintillation properties under high energy irradiation. The luminescence was studied via the combinations of the color centers, band calculation and energy transfer from NbO6 to Bi3+ in the lattices. The thermal quenching and activation energy for the luminescence were reported. β-BiNbO4 has potential applications in photoluminescence and scintillation materials. [ABSTRACT FROM AUTHOR]

Microgels are favorable for numerous applications such as drug delivery, biomaterials science and tissue engineering. Conventionally, photolithographic methods and micro-molding techniques are extensively exploited to prepare microgels; however, they are, respectively, limited to photocrosslinkable polymers and inadequate to generate serially patterned hydrogels due to the static nature of utilized molds. Herein, we proposed a simple and versatile approach, termed pneumatic-aided micro-molding (PAM), to flexibly fabricate microgels with precise control over multiple cell types and microarchitectures of hydrogels through strategically designed pneumatic microvalves. Using the PAM approach, different cells were encapsulated in various hydrogels that had well-defined geometries. Additionally, single/multiple micro-channeled cell-laden microgels were fabricated, of which the shape, number and arrangement could be finely tuned by varying microvalve configurations. Moreover, multi-compartmental microgels comprising composite hydrogel structures were engineered following a two-step PAM, which demonstrated the utility for biomimetically constructing a three-dimensional (3D) liver microtissue composed of a radially orchestrated network of hepatic cords and sinusoids. The resulting microtissue resembled the organizational complexity of the liver lobule and was applied for the evaluation of acetaminophen-induced hepatotoxicity. Collectively, the PAM strategy could be a useful and powerful tool in biomedical engineering, in vitro 3D cell culture, and fundamental biological studies. [ABSTRACT FROM AUTHOR]

Copper-free click chemistry has been used to graft quaternized poly(dimethylaminoethyl methacrylate) (QPA) modified with azide to the quantum dots (QDs) derived with dibenzocyclooctynes (DBCO). The success of the quaternary ammonium polymer-modified QDs was confirmed by ultraviolet-visible spectrophotometry (UV-Vis), fluorescence spectroscopy, zeta (ζ) potential, size distribution, and transmission electron microscopy (TEM). The QPA-modified QDs exhibited properties of selective recognition and killing of bacteria. The novelty of this study lies in fact that the synthesis method of the antimicrobial QPA-modified QDs is simple. Moreover, from another standpoint, QPA-modified QDs simultaneously possess abilities of selective recognition and killing of bacteria over mammalian cells, which is very different from the currently designed multifunctional antimicrobial systems composed of complicated systematic compositions. [ABSTRACT FROM AUTHOR]

In this paper, we designed and synthesized a novel TBET-based ratiometric fluorescent chemodosimeter, RH-Au, for Au3+. It was found that the probe RH-Au displayed highly selective, sensitive and naked-eye detection upon the addition of Au3+. The probe RH-Au can be used in the pH range 6.0–7.5 and the detection limit was determined to be as low as 2.91 nM (0.57 ppb). We also demonstrated a successful application of imaging Au3+ in living cells using RH-Au. [ABSTRACT FROM AUTHOR]

The selective binding behavior of a series of nitrile derivatives by ethylated pillar[6]arene (EtP6A) is described. This work represents the first example of complexation of neutral guests by pillar[6]arenes, although those for pillar[5]arenes have been well documented. [ABSTRACT FROM AUTHOR]

The development of a novel and simple method to trace lead ions (Pb2+) has received great attention due to its high toxicity to human health and the environment. In this paper, we describe a new polydiacetylene (PDA)-based liposome sensor for the colorimetric and fluorometric detection of Pb2+ in aqueous solution and in alginate hydrogel microbeads. In the sensor system, a dopamine group was rationally introduced into a diacetylene monomer to work as a strong binding site for Pb2+. The dopamine-functionalized monomer and 10,12-pentacosadiynoic acid (PCDA) were then incorporated into PDA liposomes in aqueous solution. After UV light-induced polymerization, deep blue colored liposome solutions were obtained. Upon the addition of various metal ions into the liposome solution, only Pb2+ could cause a distinct color change from blue to red and a dramatic fluorescence enhancement. To further improve its sensitivity and address its intrinsic aggregation, we then developed a liposome-immobilized detection system by encapsulating PDA–DA liposomes into alginate hydrogel beads through a microfluidic droplet-based method. The results showed that the PDA–DA liposome-containing hybrid hydrogel beads possessed excellent stability and high sensitivity. These interesting findings demonstrated that the PDA liposome system developed in the current study may offer a new method for Pb2+ recognition in a more efficient manner. [ABSTRACT FROM AUTHOR]

Cell sorting by filtration techniques offers a label-free approach for cell separation on the basis of size and deformability. However, filtration is always limited by the unpredictable variation of the filter hydrodynamic resistance due to cell accumulation and clogging in the microstructures. In this study, we present a new integrated microfluidic device for cell separation based on the cell size and deformability by combining the microstructure-constricted filtration and pneumatic microvalves. Using this device, the cell populations sorted by the microstructures can be easily released in real time for subsequent analysis. Moreover, the periodical sort and release of cells greatly avoided cell accumulation and clogging and improved the selectivity. Separation of cancer cells (MCF-7, MDA-MB-231 and MDA231-LM2) with different deformability showed that the mixture of the less flexible cells (MCF-7) and the flexible cells (MDA-MB-231 and MDA231-LM2) can be well separated with more than 75% purity. Moreover, the device can be used to separate cancer cells from the blood samples with more than 90% cell recovery and more than 80% purity. Compared with the current filtration methods, the device provides a new approach for cancer cell separation with high collection recovery and purity, and also, possesses practical potential to be applied as a sample preparation platform for fundamental studies and clinical applications. [ABSTRACT FROM AUTHOR]

Three-dimensional tumor culture methods offer a high degree of biological and clinical relevance to in vitro models as well as cancer therapy. However, a straightforward, dynamic, and high-throughput method for micro-manipulation of 3D tumors is not yet well established. In this study, we present a novel and simple strategy for producing biomimetic 3D tumors in a controllable, high throughput manner based on an integrated microfluidic system with well-established pneumatic microstructures. Serial manipulations, including one-step cell localization, array-like self-assembly, and real-time analysis of 3D tumors, are accomplished smoothly in the microfluidic device. The recovery of tumor products from the chip is performed by dynamic off-switch of the pneumatic microstructures. In addition, this microfluidic platform is demonstrated to be capable of producing multiple types of 3D tumors and performing the evaluation of tumor targeting by nanomedicine. The pneumatic microfluidic-based 3D tumor production shows potential for research on tumor biology, tissue engineering, and drug delivery. [ABSTRACT FROM AUTHOR]

Micropatterning technologies are emerging as an enabling tool for various microfluidic-based applications in life sciences. However, the high throughput and multiplex localization of multiple bio-components in a microfluidic device has not yet been well established. In this paper, we describe a simple and in situ micropatterning method using an integrated microfluidic device with pneumatic microstructures (PμSs) for highly controllable immobilization of both proteins and cells in a high throughput, geometry-dynamic, and multi-patterning way. The precise Pluronic F127 passivation of a microchamber surface except the PμS-blocked regions was performed and characterized, and the spatial dynamics and consistency of both the PμSs and protein/cell micropatterning were optically evaluated and quantitatively demonstrated too. Furthermore, a systematic investigation of PμS-assisted micropatterning in microfluidics was carried out. The feature of high throughput and spatial control of micropatterning can be simply realized by using the well-designed PμS arrays. Meanwhile, the co-micropatterning of different proteins (bovine serum albumin and chicken egg albumin) and cells (human umbilical vein endothelial cells and human hepatocellular carcinoma cells) in a microfluidic device was successfully accomplished with the orderly serial manipulation of PμS groups. We demonstrate that PμS-assisted micropatterning can be applied as a convenient microfluidic component for large-scale and diversified protein/cell patterning and manipulation, which could be useful for cell-based tissue organization, high-throughput imaging, protein-related interactions and immunoassays. [ABSTRACT FROM AUTHOR]

A comprehensive elucidation of the unexpected adverse events that occur in skeletal myoblast transplantation is fundamental for the optimization of myocardial therapeutic effects. However, a well-defined method to study the interactions between skeletal myoblasts and cardiomyocytes during the healing process is out of reach. Here, we describe a microfluidic method for monitoring the interactions between skeletal myoblasts and hypoxia-injured cardiomyocytes in a spatiotemporally-controlled manner, mimicking the in vivo cell transplantation process. A myocardial hypoxia environment was created using an oxygen consumption blocking reagent, carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone. Meanwhile, the interactions between the skeletal L6 myoblasts and hypoxia-injured myocardium H9c2 cells were investigated, and the effects of a L6 conditional medium on H9c2 cells were comparatively analyzed by quantitatively measuring the morphological and pathophysiological dynamics of H9c2 cells. The results showed that skeletal myoblasts could repair hypoxia-injured H9c2 cells mainly through direct cell-to-cell interactions. This simple on-chip assay for investigating myocardial repair processes may provide avenues for the in vitro screening of drug-induced cardiotoxicity. [ABSTRACT FROM AUTHOR]

The presence and quantity of rare cells in the bloodstream of cancer patients provide a potentially accessible source for the early detection of invasive cancer and for monitoring the treatment of advanced diseases. The separation of rare cells from peripheral blood, as a “virtual and real-time liquid biopsy”, is expected to replace conventional tissue biopsies of metastatic tumors for therapy guidance. However, technical obstacles, similar to looking for a needle in a haystack, have hindered the broad clinical utility of this method. In this study, we developed a multistage microfluidic device for continuous label-free separation and enrichment of rare cells from blood samples based on cell size and deformability. We successfully separated tumor cells (MCF-7 and HeLa cells) and leukemic (K562) cells spiked in diluted whole blood using a unique complementary combination of inertial microfluidics and steric hindrance in a microfluidic system. The processing parameters of the inertial focusing and steric hindrance regions were optimized to achieve high-throughput and high-efficiency separation, significant advantages compared with existing rare cell isolation technologies. The results from experiments with rare cells spiked in 1% hematocrit blood indicated ＞90% cell recovery at a throughput of 2.24 × 107 cells min−1. The enrichment of rare cells was ＞2.02 × 105-fold. Thus, this microfluidic system driven by purely hydrodynamic forces has practical potential to be applied either alone or as a sample preparation platform for fundamental studies and clinical applications. [ABSTRACT FROM AUTHOR]

Three-dimensional multicellular tumor spheroids have become critical for anticancer study since they may provide a better model than conventional monolayer cultures of cancer cells. Various methods for tumor spheroid formation have been explored. However, only one kind of hydrogel was used in these methods, which has an influence on the size and morphology of the obtained tumor spheroids. Herein, we present a microfluidic droplet-based method for the formation of multicellular tumor spheroids using alginate and matrigel mixed hydrogel beads. By on-chip changing the flow rate of the two hydrogel solutions, mixed hydrogel beads with different volume ratios between alginate and matrigel are obtained. Meanwhile, human cervical carcinoma (HeLa) cells are encapsulated in the mixed hydrogel beads. Acridine orange and propidium iodide double-staining assay shows that the viability of cells encapsulated in the mixed hydrogel beads was more than 90%. After 4 day culture, the multicellular tumor spheroids were successfully formed with spherical shape and uniform size distribution compared with spheroids formed in pure alginate beads. Cytoskeletal analysis by TRITC-phalloidin staining show that HeLa cells in the mixed hydrogel beads closely link to each other. The dose-dependent response assay of HeLa cell spheroids to vincristine show that multicellular spheroids have more powerful resistance to vincristine compared to conventional monolayer culture cells. Taken together, this novel technology may be of importance to facilitate in vitro culture of tumor spheroids for their ever-increasing utilization in modern cell-based medicine. [ABSTRACT FROM AUTHOR]

Fluoride anion (F−) significantly affects chemical, biological, and environmental processes. Fluoride recognition and detection have received increasing attention. Convenient, effective, and sensitive fluorescent probes for F− should urgently be designed and synthesized. In this study, we describe a strategy for constructing two triarylborane-based fluoride fluorescent probes: 2,7,12-tri(2-(5-(dimesitylboryl)thiophen-2-yl)ethynyl)-5,5′,10,10′,15,15′-hexaethyltruxene (C3B3) with π–3A (acceptor) configuration and 2,7-di(N,N-diphenylamino)-12-(5-(dimesitylboryl)thiophen-2-yl)-5,5′,10,10′,15,15′-hexaethyltruxene (N2SB) with 2D (donor)–π–A configuration. The loss of color of the tetrahydrofuran solution of these probes from greenish yellow suggests that they can conveniently monitor F− at a low concentration (10 μM) free of apparatus. The different structural features of these probes varied their fluorescent responses to F−. The single-photon fluorescence intensity of C3B3 declined to 90% upon the addition of 4.5 equivalents of F− to its tetrahydrofuran solution. However, the single-photon fluorescence intensity of N2SB was enhanced six-fold upon addition of 2.5 equivalents of the F−. Under the experimental conditions, the detection limits of the two probes for F− can reach 12–13 μM (C3B3) and 3–5 μM (N2SB). The ability of the two probes in detecting F− in their toluene solutions in the two-photon mode was also investigated. The sensitive two-photon fluorescence responses of both probes make them excellent two-photon fluorescence probes. [ABSTRACT FROM AUTHOR]

Graphene oxides with different surface charges were fabricated from carboxylated graphene oxide by chemical modification with amino- (–NH2), poly-m-aminobenzene sulfonic acid- (–NH2/–SO3H), or methoxyl- (–OCH3) terminated functional groups. The chemically functionalized graphene oxides and the carboxylated graphene oxide were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy, UV-Vis spectrometry, ζ potential measurements, field emission scanning electron microscopy, and contact angle analyses. Subsequently, the resulting graphene oxides were used as substrates for culturing primary rat hippocampal neurons to investigate neurite outgrowth and branching. The morphological features of neurons that directly reflect their potential capability in synaptic transmission were characterized. The results demonstrate that the chemical properties of graphene oxide can be systematically modified by attaching different functional groups that confer known characteristics to the substrate. By manipulating the charge carried by the functionalized graphene oxides, the outgrowth and branching of neuronal processes can be controlled. Compared with neutral, zwitterionic, or negatively charged graphene oxides, positively charged graphene oxide was found to be more beneficial for neurite outgrowth and branching. The ability to chemically modify graphene oxide to control neurite outgrowth could be implemented clinically, especially in cases wherein long-term presence of outgrowth modulation is necessary. [ABSTRACT FROM AUTHOR]

The supramolecular interaction between the host molecule β-cyclodextrin (β-CD) and the guest molecule adamantane is extensively applied in several disciplines. However, recent studies on the applications of this molecular recognition mainly focused on glass, silicon, and gold substrates. Few studies have explored the field of poly(dimethylsiloxane) (PDMS), an optically transparent elastomer widely used in biological microfluidic devices. In the present study, various functional group-modified adamantyl-terminated dendronized molecules were synthesized via an efficient and facile route. The binding of adamantyl-terminated dendronized molecules onto β-CD-conjugated PDMS surfaces and their reversible dissociation from PDMS surfaces through the competitive mechanism of β-CD-N3 were studied. The results showed that the dissociation is relatively slow compared with the binding, and the former process can be accelerated through exchanging the original β-CD-N3 solution with a fresh one. Afterward, more complex multilayer assemblies were constructed on PDMS surfaces using the host–guest interaction between adamantane and β-CD as well as between biotin and streptavidin. A further study on the association and dissociation of the established multilayer assemblies showed that the assembly constructed with a biotinylated monoadamantyl-terminated molecule has a reversible property, whereas that with a biotinylated triadamantyl-terminated molecule has an irreversible property. These results demonstrated that the reversible properties of the fabricated assembly can be easily modulated on the PDMS surfaces by regulating the valence of the supramolecular interaction between adamantane and β-CD. [ABSTRACT FROM AUTHOR]

Iron (Fe 3+ ) is one of the most essential elements in the human body; deficiency or overdose of Fe 3+ may have adverse effects on human health and immunity. Hence, it is essential to establish a sensitive and selective method for ion detection. In this study, novel green fluorescent N-doped carbon dots (N-CDs) were prepared with caffeic acid as the carbon source via a simple hydrothermal method. The solution of the as-prepared N-CDs exhibits 21.5% quantum yield, good salt stability, excellent water solubility, low cytotoxicity and good photobleaching resistance. The N-CDs can be used as a fluorescent probe for the detection of Fe 3+ ions in aqueous solutions and bioimaging in living cells.

β-BiNbO4 with a high temperature triclinic form was prepared via a high-temperature solid-state reaction ceramic method. Structural refinement and surface characteristic studies were performed. The optical absorption, and electronic calculation of the band structures and density of states were also studied. β-BiNbO4 ceramic has an indirect transition with a band energy of 3.05 eV. The valence band is dominated by O-2p states whereas the conduction band has predominantly Nb 4d and Bi 6s character. The intrinsic luminescence properties of β-BiNbO4 were reported, and present a blue emission band peak at 435 nm under the excitation of UV light. The β-BiNbO4 ceramic presents scintillation properties under high energy irradiation. The luminescence was studied via the combinations of the color centers, band calculation and energy transfer from NbO6 to Bi(3+) in the lattices. The thermal quenching and activation energy for the luminescence were reported. β-BiNbO4 has potential applications in photoluminescence and scintillation materials.

In this paper, we designed and synthesized a novel TBET-based ratiometric fluorescent chemodosimeter, RH-Au, for Au(3+). It was found that the probe RH-Au displayed highly selective, sensitive and naked-eye detection upon the addition of Au(3+). The probe RH-Au can be used in the pH range 6.0-7.5 and the detection limit was determined to be as low as 2.91 nM (0.57 ppb). We also demonstrated a successful application of imaging Au(3+) in living cells using RH-Au.

Recent microfluidic advancements in oxygen gradients have greatly promoted controllable oxygen-sensitive cellular investigations at microscale resolution. However, multi-gradient integration in a single microfluidic device for tissue-mimicking cell investigation is not yet well established. In this study, we describe a method that can generate oxygen and chemical concentration gradients in a single microfluidic device via the formation of an oxygen gradient in a chamber and a chemical concentration gradient between adjacent chambers. The oxygen gradient dynamics were systematically investigated, and were quantitatively controlled using simple exchange between the aerial oxygen and the oxygen-free conditions in the gas-permeable polydimethylsiloxane channel. Meanwhile, the chemical gradient dynamics was generated using a special channel-branched device. For potential medical applications of the established oxygen and chemical concentration gradients, a tumor cell therapy assessment was performed using two antitumor drugs (tirapazamine and bleomycin) and two tumor cell lines (human lung adenocarcinoma A549 cells and human cervical carcinoma HeLa cells). The results of the proof-of-concept experiment indicate the dose-dependent antitumor effect of the drugs and hypoxia-induced cytotoxicity of tirapazamine. We demonstrate that the integration of oxygen and chemical concentration gradients in a single device can be applied to investigating oxygen- and chemical-sensitive cell events, which can also be valuable in the development of multi-gradient generating procedures and specific drug screening.