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Exosomal microRNAs (miRNAs) play a pivotal role in intercellular communication, regulating gene expression in target cells, and hold significant promise as cancer biomarkers for early detection and screening. However, achieving precise and viable detection of exosomal miRNAs remains a challenge. This paper proposes an all-in-one detection strategy for breast cancer-derived exosomal miRNA-21 on a pen-based paper chip (PPC). The PPC is constructed using a modified automatic pen and lateral flow assay (LFA), which results in a cost-effective fabrication process. The user only needs to add the sample and trigger the top of the self-contained PPC after a period of time to complete the entire detection process. To enhance the sensitivity of exosomal miRNA testing, an enzyme-free catalyzed hairpin assembly (CHA) is further introduced, enabling highly sensitive detection of miRNA-21 with a limit of detection (LOD) of 25 fmol. Additionally, the detection of miRNAs in differentially-expressed cells and clinical samples has also been successfully achieved with high specificity. Overall, the proposed PPC provides an effective tool for detecting early cancer, monitoring diseases, and establishing point of care testing (POCT). [ABSTRACT FROM AUTHOR]

Angiogenesis is one of the most essential developmental processes and plays a key role in organogenesis and tumorigenesis in which epithelial cells proliferate and migrate, thus resulting in sprouting and extension of the existing vasculature. The study of angiogenesis in vivo is limited by difficulties related to imaging of the fine structure of vascular sprouting within non-transparent bulk tissue. Thus, many model systems have been proposed in recent years. However, to meet the urgent need for high-throughput studies and screening, further improvements are still required, particularly in terms of scaling-up. In this study, we combined microchip fabrication with the culture of three-dimensional (3D) spheroids, thus providing a platform for 3D multilayer angiogenesis-on-a-chip. Using this platform, we investigated the precise effects of vascular endothelial growth factor (VEGF) on angiogenesis. In comparison with two-dimensional (2D) angiogenesis assays, our 3D angiogenesis platform demonstrated superior sprouting and provided proof of concept that our 3D biomimetic angiogenesis-on-a-chip could serve as a powerful tool for pro- or anti-angiogenesis candidate drug screening. [ABSTRACT FROM AUTHOR]

The solar-to-hydrogen conversion efficiency in photocatalytic water splitting heavily depends on the accumulation of multiple electrons at the catalytically active sites and rapid charge transport/separation. Herein, we demonstrate the construction of 0D-2D nickel-doped and Ti3C2TX MXene (MN)-encapsulated transition metal chalcogenide quantum dot (TMC QD:Ni)/Ti3C2TX MN heterostructures via an elaborate electrostatic self-assembly strategy. The mechanistic studies revealed that the defects induced by atomic-level foreign metal ion doping create a mid-bandgap state, which broadens the optical absorption range and extends the photo-excited carrier lifetime of the TMC QDs. The density functional calculation results verified that Ni2+ ion doping introduces a donor impurity level and increases the density of state at the valence band maximum, leading to a significant increase in the number of active sites and lower energy barrier for photocatalytic hydrogen evolution. The subsequent self-assembly of TMC QDs:Ni on the Ti3C2TX MN framework further accelerates the charge separation and transfer due to the formation of an ideal unidirectional electron migration pathway by Ti3C2TX MN, which functions as an electron-withdrawing mediator. The synergistic effect of Ni2+ ion doping and Ti3C2TX MN decoration significantly decreases the charge transfer resistance at the photosensitizer (TMC QD)/co-catalyst (Ti3C2TX MN) interface and promotes the chemisorption of protons on the catalyst surface, resulting in an excellent solar-to-hydrogen conversion efficiency. Our work provides valuable guidance for the rational design of high-efficiency photocatalysts via precise atomic-level metal ion doping and co-catalyst modulation towards emerging artificial photosynthesis. [ABSTRACT FROM AUTHOR]

The outbreak of global infectious diseases has posed a significant threat to public health, requiring the rapid and accurate diagnosis of pathogens promptly for the society to implement immediate control measures to prevent widespread pandemics. In this work, a magnet-actuated microfluidic array chip (MMAC) is developed with integrated sample processing and nucleic acid amplification for the rapid detection of multiple pathogens by loop-mediated isothermal amplification. In comparison to previous works, where fluid control was dependent on external equipment or finger-based manual pressing, the fluid control of the MMAC is realized by magnetically actuating a ferric oxide (Fe3O4) doped polydimethylsiloxane (PDMS) layer that separates the sample from the LAMP reagent in a high-throughput manner, which not only reduces the complexity of fluid control but also enhances the repeatability of detection by eliminating variations in operation by different users. Examination with a testing sample containing Salmonella typhimurium and Escherichia coli showed high specificity for pathogen detection without cross-contamination. The lowest detection concentration was 5.2 copies per μL for Salmonella typhimurium with a detection time of 60 min. The proposed method demonstrated the simultaneous detection of multiple pathogens, which is potentially helpful in applications of immediate diagnosis. [ABSTRACT FROM AUTHOR]

In recent years, atomically precise metal nanoclusters (NCs) have demonstrated fascinating applicability in solar energy conversion due to their unique atomic stacking arrangements, quantum size effect and abundant active sites. Nevertheless, ultra-short carrier lifetimes and poor stabilities impede the construction of robust metal-NC-based photosystems. Herein, positively charged poly(diallyl-dimethylammonium chloride) (PDDA) and tailor-made negatively charged L -glutathione (GSH)-capped Agx@GSH [Ag9(SG)6, Ag16(SG)9 and Ag31(SG)19] NCs are used as building blocks and alternately deposited on a one-dimensional wide-band-gap metal oxide (MO) substrate using a facile and general layer-by-layer (LbL) assembly strategy to design a highly efficient spatially directional charge transport pathway in multilayered photoanodes. The electrons photoexcited from the periodically stacked Agx@GSH [Ag9(SG)6, Ag16(SG)9 and Ag31(SG)19] NC layers concurrently and unidirectionally migrate to the MO substrate, while the ultrathin PDDA intermediate layer serves as an interfacial electron-withdrawing charge mediator to accelerate the transport of the carriers photoexcited over the neighboring Agx@GSH [Ag9(SG)6, Ag16(SG)9 and Ag31(SG)19] NC layers. Benefiting from the charge transfer enhancement, these LbL-assembled multilayered MO/(PDDA/Agx NCs)n heterostructured photoanodes demonstrate significantly enhanced photoelectrochemical water oxidation performance under visible light irradiation due to the generation of unidirectional and spatially separated tandem charge transfer channels, which remarkably reduces the charge recombination and prolongs the carrier lifetime of the metal NCs. Moreover, we ascertain that this conceptual multilayered nanoarchitecture design and tandem charge transport are universal. [ABSTRACT FROM AUTHOR]

Cells in their native microenvironment are subjected to varying combinations of biochemical cues and mechanical cues in a wide range. Although many signaling pathways have been found to be responsive for extracellular cues, little is known about how biochemical cues crosstalk with mechanical cues in a complex microenvironment. Here, we introduced heterogeneous droplets on a microchip, which were rapidly assembled by combining wettability-patterned microchip and programmed droplet manipulations, for a high-throughput cell screening of the varying combinations of biochemical cues and mechanical cues. This platform constructed a heterogeneous droplet/microgel array with orthogonal gradual chemicals and materials, which was further applied to analyze the cellular Wnt/β-catenin signaling in response to varying combinations of Wnt ligands and substrate stiffness. Thus, this device provides a powerful multiplexed bioassay platform for drug development, tissue engineering, and stem cell screening. [ABSTRACT FROM AUTHOR]

We for the first time report that the activated CRISPR-Cas12a system trans-cleaves DNA G-quadruplexes (G4). The cleavage activity on human telomere G4 and TBA G4 was investigated and verified by FRET, CD, gel electrophoresis and NMR. We believe that this finding will pave a new avenue for advancing the applications of CRISPR-Cas12a and G4 in biosensing and biochemistry. [ABSTRACT FROM AUTHOR]

Colorectal cancer is associated with changed IgG glycosylation, but the alteration in specific subclasses of IgG is unknown. Initially, we optimized five common IgG glycopeptide enrichment methods to acquire a comprehensive profile of IgG glycopeptides. However, an incomplete tryptic digestion of IgG occurred when using an ordinary protease to protein ratio, which significantly impacted the final statistical analysis. Herein, we introduced a two-step enzymatic digestion, enabling the complete digestion of IgG glycopeptides and further improving the detection intensity of the target glycopeptides. In order to rapidly process and automatically integrate the MS data, we developed a simple and effective code using MATLAB. Following statistical analysis, we observed that IgG1_H3N4F1 and IgG1_H3N4 were substantially increased in CRC, while IgG1_H5N5F1, IgG1_H5N4F1S1 and IgG2_H5N4F1 were markedly decreased. A further evaluation of the diagnostic performance showed that they all achieved a fair performance in discriminating the patients from the normal. In terms of the glycan features, it was demonstrated that the CRC progression was associated with increased agalactosylation, and the decreased digalactosylation and galactosylation per antenna on the diantenna glycans of IgG1 and IgG2. Concurrently, the decreased sialylation of IgG1 was strongly correlated with CRC. Moreover, an analysis of tumor-specific glycosylation showed that the alterations of IgG glycosylation were more significant in colon cancer, and no obvious difference was observed between colon and rectal cancer. This study comprehensively optimized the glycopeptide enrichment methods, evaluated the enzymatic digestion effect, and explored the association between CRC progression and subclass-specific glycosylation. [ABSTRACT FROM AUTHOR]

The directed motility of organisms in response to fluid velocity, which is called rheotaxis, is important in the life cycle of C. elegans, enabling them to navigate their environment and maintain their positions in the presence of adverse flow. Thus, to study the mechanism underlying rheotaxis behavior and reveal information on parasitic diseases, the profile analysis of the rheotaxis response in worm populations with high resolution in well-defined fluid environments is highly desirable. In this work, we presented a rapid and robust microfluidic approach to quantitatively analyze the rheotaxis behavior of worms in response to velocity. The flow-based microfluidic chip contained six helical spline microchannels for generating six flow streams with different flow velocities. Since the worms loaded in the chip would swim upstream into channels, the distribution of the worms in response to the different flow velocities was successfully monitored for the quantitative analysis of their rheotaxis behavior using this microfluidic chip. The results indicated that the rate range of around 50 μm s−1 was the most favorable flow velocity for the wild-type worms. Further, we analyzed ASH neuron-blocked worms and found that the functionally defective ASH neurons inhibited their sensitivity to flow rate. In addition, the rheotaxis analysis of the mutant worms indicated that TRP mechanosensory channels and serotonin signals also play a regulatory role in the rheotaxis response of these worms. Thus, our microfluidic method provides a useful platform to study the rheotaxis behaviors in C. elegans and can be further applied for anti-parasitic drug tests. [ABSTRACT FROM AUTHOR]

Three analogous lanthanide-containing complexes were isolated, with the molecular formula [Ln4(μ3-OH)2(tmhd)4L6]·2CH3CN (where Ln = Eu(1), Gd(2) and Dy(3); HL = 5-phenyl-8-hydroxylquinoline; and Htmhd = 2,2,6,6-tetramethyl-3,5-heptanedione). Single-crystal X-ray diffraction measurements performed on 1–3 revealed that they were all composed of [Ln4(μ3-OH)2] centers with butterfly-shaped arrangements. Investigations into the luminescence properties and lifetime of 1 showed characteristic emission peaks of the Eu3+ ion and an average luminescence lifetime of 9.26 μs. Detailed magnetic studies suggested that antiferromagnetic interactions existed in 2 and 3, and that there was a remarkable magnetocaloric effect with a −ΔSm value of 17.94 J K−1 kg−1 for 2, and a slow magnetic relaxation process with an energy barrier ΔE/kB of 35.8 K for 3. [ABSTRACT FROM AUTHOR]

Studies of chemo-sensing in C. elegans to fluctuating gaseous cues are limited due to the lack of a method of precise gas control. In this paper, we describe a microfluidic-based on-demand gas segmented flow generator for performing fluctuating gaseous stimulations to worms. This highly versatile and programmable micro-device integrated with pneumatic valves for flexible and stable gas flow control and worm immobilization enabled us to examine the temporal features of neuronal response to multiple gas pulses with sub-second precision. As a result, we demonstrated the capability of the micro-device to generate repetitive gaseous chemical pulses with varying durations. By characterizing intracellular calcium signals, we showed that URX sensory neurons were sensitive to O2 pulses with duration of more than 0.5 s. Furthermore, URX neuronal adaptation and recovery in response to gaseous chemical pulses were investigated by varying the durations and intervals. The developed microfluidic system is shown to be a useful tool for studying the dynamics of in vivo gas-evoked neuronal responses and revealing the temporal properties of environmental stimulations. [ABSTRACT FROM AUTHOR]

Active control over the cell gradient is essential for understanding biological systems and the reconstitution of the functionality of many types of tissues, particularly for organ-on-a-chip. Here, we propose a three-dimensional (3D) microfluidic strategy for generating controllable cell gradients. In this approach, a homogeneous cell suspension is loaded into a 3D stair-shaped PDMS microchannel to generate a cell gradient within 10 min by sedimentation. We demonstrate that cell gradients of various profiles (exponential and piecewise linear) can be achieved by precisely controlling the height of each layer during the fabrication. With sequential seeding, we further demonstrate the generation of two overlapping cell gradients on the same glass substrate with pre-defined designs. The cell gradient-based QD cytotoxicity assay also demonstrated that cell behaviors and resistances were regulated by the changes in cell density. These results reveal that the proposed 3D microfluidic strategy provides a simple and versatile means for establishing controllable gradients in cell density, opening up a new avenue for reconstructing functional tissues. [ABSTRACT FROM AUTHOR]

C. elegans as a powerful model organism has been widely used in fundamental biological studies. Many of these studies frequently need a large number of different stage-synchronized worms due to the stage-specific features of C. elegans among 4 distinct larval stages and the adult stage. In this work, we present an interesting and cost-effective microfluidic approach to realize simultaneous sorting of C. elegans of different developmental stages by deflecting electrotaxis. The microfluidic device was fabricated using PDMS consisting of symmetric sorting channels with specific angles, which was further hybridized to an agarose plate. While applying an electric field, different stages of C. elegans would crawl to the negative pore with different angles due to their deflecting electrotaxis. Thus, the worms were separated and synchronized by stages. lon-2 mutant was further used to study this electrotactic response and the results indicated that the body size plays a key role in determining the deflecting angle in matured adult worms. In addition to discriminating wild-type hermaphrodites, it could also be employed to sort mutants with abnormal development sizes and males. Therefore, our device provided a versatile and highly efficient platform for sorting C. elegans to meet the requirement of large numbers of different stage-synchronized worms. It can also be further used to investigate the neuronal basis of deflecting electrotaxis in worms. [ABSTRACT FROM AUTHOR]

Kinetic measurement of biomacromolecular interaction plays a significant role in revealing the underlying mechanisms of cellular activities. Due to the small diffusion coefficient of biomacromolecules, it is difficult to resolve the rapid kinetic process with traditional analytical methods such as stopped-flow or laminar mixers. Here, we demonstrated a unique continuous-flow laminar mixer based on microfluidic dual-hydrodynamic focusing to characterize the kinetics of DNA–protein interactions. The time window of this mixer for kinetics observation could cover from sub-milliseconds to seconds, which made it possible to capture the folding process with a wide dynamic range. Moreover, the sample consumption was remarkably reduced to ＜0.55 μL min−1, over 1000-fold saving in comparison to those reported previously. We further interrogated the interaction kinetics of G-quadruplex and the single-stranded DNA binding protein, indicating that this novel micromixer would be a useful approach for analyzing the interaction kinetics of biomacromolecules. [ABSTRACT FROM AUTHOR]

Two-photon excited (TPE) calcium fluorescent probes are designed and synthesized based on internal charge transfer (ICT) with high Ca2槷⭲ and large two-photon action cross section, which can be used in living cells and detected with two-photon microscopy (TPM). [ABSTRACT FROM AUTHOR]

Point of care testing (POCT) of nucleic acids holds significant importance in the realm of infectious disease prevention and control, as well as the advancement of personalized precision medicine. Nevertheless, conventional nucleic acid testing methods continue to face challenges such as prolonged detection times and dependence on extensive specialized equipment and personnel, rendering them unsuitable for point of care applications. Here, we proposed an innovative active centrifugal microfluidic system (ACMS) for automatic nucleic acid extraction, encompassing modules for active valve control and magnetic control. An on-chip centrifugal puncture valve (PV) was devised based on the elastic tolerance differences between silicone membranes and tinfoils to release pre-embedded liquid reagents on demand. Furthermore, we have utilized the returnable valve (RV) technology to accurately control the retention and release of liquids, leveraging the high elastic tolerance of the silicone membrane. By incorporating an online controllable magnetic valve, we have achieved controlled and rapid aggregation and dispersion of magnetic beads. The final chip encapsulates multiple reagents and magnetic beads necessary for nucleic acid extraction. Upon sample addition and loading into the instrument, automated on-chip sample loading and nucleic acid extraction, purification, and collection can be accomplished within 30 minutes, halving the overall operation time and even increasing the efficiency of pseudovirus extraction by three orders of magnitude. Consequently, real-time fluorescence quantitative PCR amplification has successfully detected multiple targets of the SARS-CoV-2 virus (with an impressive detection limit as low as 10 copies per μL), along with targeted sequencing analysis yielding a conformity rate of 99%.

The core factors affecting the efficiency of photocatalysis are predominantly centered on controllable modulation of anisotropic spatial charge separation/transfer and regulating vectorial charge transport pathways in photoredox catalysis, yet it still meets with limited success. Herein, we first conceptually demonstrate the rational design of unidirectional cascade charge transfer channels over transition metal chalcogenide nanosheets (TMC NSs: ZnIn 2 S 4 , CdS, CdIn 2 S 4 , and In 2 S 3 ), which is synergistically enabled by a solid-state non-conjugated polymer, i.e. , poly(diallyldimethyl ammonium chloride) (PDDA), and MXene quantum dots (MQDs). In such elaborately designed photosystems, an ultrathin PDDA layer functions as an intermediate charge transport mediator to relay the directional electron transfer from TMC NSs to MQDs that serve as the ultimate electron traps, resulting in a considerably boosted charge separation/migration efficiency. The suitable energy level alignment between TMC NSs and MQDs, concurrent electron-withdrawing capabilities of the ultrathin PDDA interim layer and MQDs, and the charge transport cascade endow the self-assembled TMC/PDDA/MQD heterostructured photosystems with conspicuously improved photoactivities toward anaerobic selective reduction of nitroaromatics to amino derivatives and photocatalytic hydrogen evolution under visible light irradiation. Furthermore, we ascertain that this concept of constructing a charge transfer cascade in such TMC-insulating polymer-MQD photosystems is universal. Our work would afford novel insights into smart design of spatial vectorial charge transport pathways by precise interface modulation via non-conjugated polymers for solar energy conversion., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Oxides formed by electrochemical treatment of metals frequently have properties and structures very different from the respective bulk oxides. Here, electronic structure and chemical composition were investigated for the oxide formed on polycrystalline zinc after electrochemical oxidation, and after subsequent reduction, in a Na2CO3 electrolyte. Photoluminescence and spectroscopic ellipsometry show the presence of states deep in the ZnO band gap in the oxidized sample, which consists of a highly disordered oxide. These states determine the absorption of light in the visible spectral range. After reduction, the characteristics of the ZnO electronic structure have disappeared, leaving a defect-dominated material with a band gap of ~1.8 eV. Complementary detailed analysis of the morphology of the resulting surfaces shows hexagon-shaped metallic Zn-"nanoplates" to be formed in the reduction step. The optical appearance of the surfaces is dark, because of their efficient extinction of light over a large part of the visible spectrum. The optical appearance is a result of changed surface morphology and electronic structure of the oxide film. Such materials may possess interesting applications in photocatalysis or photoelectrochemistry.

Surface-enhanced Raman spectroscopy (SERS) benefits from the enhanced electromagnetic field of the localized surface plasmon resonance effect of metallic (especially coinage metals) nanoparticles or nanostructures. The detection sensitivity and reproducibility of SERS measurement appear to be the two critical issues in SERS. To solve the problem associated with traditional nanoparticle aggregates and SERS substrates, we propose in this work single particle SERS. We prepared uniform gold microspheres with controllable size and surface roughness using an etching-assisted seed-mediated method. Single particle dark-field spectroscopy and SERS measurements show that particles with a larger roughness give a stronger SERS signal, but still retain a good reproducibility. This study points to the promising future of the practical application of the single particle SERS technique for trace analysis.

Overactive and overexpressed kinases have been implicated in the cause and progression of many cancers. Kinase inhibitors offer a targeted approach for treating cancers associated with increased or deregulated kinase activity. Often, however, cancer cells exhibit initial resistance to these inhibitors or evolve to develop resistance during treatment. Additionally, cancers of any one tissue type are typically heterogeneous in their oncogenesis mechanisms, and thus diagnosis of a particular type of cancer does not necessarily provide insight into what kinase therapies may be effective. For example, while some lung cancer cells that overexpress the epidermal growth factor receptor (EFGR) respond to treatment with EGFR kinase inhibitors, overexpression or hyperactivity of Met kinase correlates with resistance to EGFR kinase inhibitors. Here we describe a microfluidic-based assay for quantifying Met kinase activity in cancer cell lysates with the eventual goals of predicting cancer cell responsiveness to kinase inhibitors and monitoring development of resistance to these inhibitors. In this assay, we immobilized a phosphorylation substrate for Met kinase into macroporous hydrogel micropillars. We then exposed the micropillars to a cancer cell lysate and detected substrate phosphorylation using a fluorescently conjugated antibody. This assay is able to quantify Met kinase activity in whole cell lysate from as few as 150 cancer cells. It can also detect cells expressing overactive Met kinase in a background of up to 75% non-cancerous cells. Additionally, the assay can quantify kinase inhibition by the Met-specific kinase inhibitors SU11274 and PHA665752, suggesting predictive capability for cellular response to kinase inhibitors.

Aiming to solve the problem of simulation of the potential dependent surface Raman spectra of anion containing surface complexes on electrodes, we developed a new simulation model by adding different cations (Li(+), Na(+), K(+), Rb(+) or Cs(+)) attached to the bottom layer of a large metallic cluster while the surface complex sits on the top layer.

We present a microfluidic sample introduction approach based on a novel flow control mechanism, hydrodynamic gated injection. It has the advantages of easy and flexible flow control, similar to its analog, electrokinetic gated injection, but exhibits the unique properties of strong driving force and good biocompatibility, ideal for applications involving live biological samples. Theories for hydrodynamic gating were proposed and validated by both numerical simulations and flow visualization experiments. An investigation with fluorescein revealed that pico-liter samples can be injected with high repeatability (RSD <1.9%). Selective injections of GFP-transfected nematode eggs were demonstrated with a survival rate of >95%. We expect the developed method to be potentially useful for microfluidic cell and organism analysis, either as a sample introduction module or a stand-alone analyzer.

In the present paper, a study was undertaken of molecular transport in ploy(dimethylsiloxane) microchannels that were fabricated by ultraviolet (UV)-photolithography and synchrotron radiation (SR)-lithography characterized and compared for microchip capillary electrophoresis by evaluating in-channel molecular dispersion. A fluorescent tag, sulforhodamine B was used as the probing molecule. It was found that microchannels made by SR-lithography fabrication were superior to those made by UV-photolithography fabrication in terms of molecular transport performance. A deep insight into surface conditions characterized by scanning electron microscopy suggested it was related to the difference in surface roughness. Chromatographic retention in electropherograms further supported such a conclusion, which depended on the phase ratio of the channel surface. The results revealed for PDMS microchannels in this work were in good agreement with the phenomenon found for glass microchannels in the literature.