Interfacial Supra-Assembly of Copolymer Nanoparticles Enables the Formation of Nanocomposite Crystals with a Tunable Internal Structure.

It is highly desirable but technically challenging to precisely control the spatial composition and internal structure of crystalline nanocomposite materials, especially in a one-pot synthetic route. Herein, we demonstrate a versatile pathway to tune the spatial distribution of guest species within a host inorganic crystal via an incorporation strategy. Specifically, well-defined block copolymer nanoparticles, poly(methacrylic acid)x-block-poly(styrene-alt-N-phenylmaleimide)y [PMAAx-P(St-alt-NMI)y], are synthesized by polymerization-induced self-assembly. Such anionic nanoparticles can supra-assemble onto the surface of larger cationic nanoparticles via an electrostatic interaction, forming colloidal nanocomposite particles (CNPs). Remarkably, such CNPs can be incorporated into calcite single crystals in a spatially controlled manner: the depth of CNPs incorporation into calcite is tunable. Systematic investigation indicates that this interesting phenomenon is governed by the colloidal stability of CNPs, which in turn is dictated by the PMAAx-P(St-alt-NMI)y adsorption density and calcium ion concentration. This study opens up a general and efficient route for the preparation of a wide range of crystalline nanocomposite materials with a controlled internal composition and structure.

A Novel Cell Volume Sensor for Real-Time Analysis of Ca2+-Activated K+ Channel.

Potassium channels play a vital role in cell volume regulation. A cell volume sensor was constructed by integrating regulatory volume decrease (RVD) with quartz-crystal microbalance (QCM) for studying potassium channels and their expression. The sensor successfully monitored the K+ channel's activities during RVD by sensitive and noninvasive means. It showed that Ca2+ activated the K+ channel (KCa) and enhanced the RVD level. The inhibition of blockers on K+ channels exhibited an obvious difference in RVD level between normal and cancerous nasopharyngeal cells, suggesting that the KCa channel contributes a dominant role to the RVD function and provides an approach to identify the activation of various K+ channels.

Morphology Dictated Immune Activation with Framework Nucleic Acids.

Framework nucleic acids (FNAs) of various morphologies, designed using the precise and programmable Watson-Crick base pairing, serve as carriers for biomolecule delivery in biology and biomedicine. However, the impact of their shape, size, concentration, and the spatial presentation of cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) on immune activation remains incompletely understood. In this study, representative FNAs with varying morphologies are synthesized to explore their immunological responses. Low concentrations (50 nM) of all FNAs elicited no immunostimulation, while high concentrations of elongated DNA nanostrings and tetrahedrons triggered strong activation due to their larger size and increased cellular uptake, indicating that the innate immune responses of FNAs depend on both dose and morphology. Notably, CpG ODNs' immune response can be programmed by FNAs through regulating the spatial distance, with optimal spacing of 7-8 nm eliciting the highest immunostimulation. These findings demonstrate FNAs' potential as a designable tool to study nucleic acid morphology's impact on biological responses and provide a strategy for future CpG-mediated immune activation carrier design.

Multi-Analyte Discriminated ECL via Photonic Crystal-Enhanced Selectivity.

Electrochemiluminescence (ECL) has numerous merits such as high sensitivity and specificity for the detection applications on pharmacy, food safety, immunoassay, disease diagnosis, environmental monitoring, nucleic acid assay, and clinical treatment. However, the insufficiency of ECL luminescent reagents is restricting their adoption on complex systems or multi-analyte detections. In this work, to improve the selectivity and discrimination of ECL detection with one or less luminescent reagent, we employed multi-stopband photonic crystals (PCs) to enhance assigned ECL. The discrimination of ECL was well investigated to establish the quantitative description with PC stopbands. The multi-stopband PC electrode can facilely achieve 10 antibiotics qualitative and quantitative analysis with 100% accuracy and 0.44 µM LOD in PBS buffer and human serum. The selectivity of ECL detection for multi-analytes can be improved via designed PC luminescence amplifications. The exploration on PC selectivity for ECL enhancement will promote the realistic application of the ECL technique and contribute to the facile and efficient optical platform for clinical or health monitoring.

Fully Methylammonium-Free Stable Formamidinium Lead Iodide Perovskite Solar Cells Processed under Humid Air Conditions.

Fabricating perovskite solar cells (PSCs) in ambient air condition is beneficial for lowering the processing cost and boosting the commercialization. Formamidinium lead iodide (FAPbI3) is an attractive candidate for efficient PSCs; however, it easily suffers from degradation and phase transition in the presence of ambient moisture. Methylammonium (MA) cation is commonly incorporated to stabilize FAPbI3, whereas the residual MA tends to deteriorate the thermal and operational stability. Herein, we report a MA-free strategy to fabricate high-quality α-FAPbI3 films and inverted PSCs under open air conditions with a relative humidity (RH) of 60 ± 10%. The incorporation of phenylethylammonium iodide (PEAI) effectively inhibits the decomposition and phase transition of FAPbI3 during its crystallization in humid air. Accordingly, phase-pure α-FAPbI3 perovskite films with significantly reduced δ-FAPbI3 and PbI2 content are successfully obtained. In addition, introducing PEAI strongly enhances the crystallinity of FAPbI3 perovskite films, thereby yielding enlarged grain sizes and reduced grain boundaries. Defects at the grain boundaries and surface are further passivated by PEAI addition, so that the trap state density is significantly decreased. As a result, the non-radiative recombination is effectively suppressed and the charge carrier transport is promoted. The inverted device optimized with a suitable PEAI concentration exhibits an enhanced power conversion efficiency (PCE) of 17.83%, which significantly surpasses the control device (12.29% PCE). Moreover, the PEAI optimized FAPbI3 PSCs demonstrate strongly improved long-term stability, with nearly 97% PCE maintained after 27-day storage under ambient conditions. This work provides a feasible way to fabricate PSCs in ambient air for promoting their wide range of applications.

A Sensitive Electrochemiluminescence Urea Sensor for Dynamic Monitoring of Urea Transport in Living Cells.

A multiple signal-amplified electrochemiluminescence (ECL) urea sensor was designed based on a self-enhanced probe and SiO2 photonic crystals for dynamic tracking of urea transmembrane transport. The self-enhanced probe (AuNR@Ru-LA) prepared by loading polyethyleneimine (PEI), lactobionic acid (LA), and Ru(dcbpy)32+ on gold nanorods (AuNRs) generated an initial ECL signal, and then the intensity was multiple-amplified by the enhanced light-scattering effect of SiO2 photonic crystals and the co-reaction with urea. The as-prepared sensor exhibited excellent performance for the detection of urea in the range of 1.0 × 10-10 to 1.0 × 10-4 M with a detection limit of 8.8 × 10-11 M at (3σ)/S. The AuNR@Ru-LA probes were labeled on HepG2 cells to construct a cytosensor with a detection range of 1.0 × 103 to 2.0 × 106 cells mL-1. In addition, the dynamic changes of the extracellular urea concentration were tracked by monitoring the ECL signal of the cytosensor to study urea transmembrane transport. The developed strategy realized the amplification of multiple ECL signals and the tracking of urea transmembrane transport, which provided a novel dynamic detection method for small biomolecules.

QCM sensor provides insight into the role of pivotal ions in cellular regulatory volume decrease.

All vertebrate cells generally self-regulate for sustaining homeostasis and cell functions. As a major regulatory mechanism, regulatory volume decrease (RVD) occurs in hypotonicity-induced cell swelling, and then shrinking by the efflux of intracellular osmolytes and water, in which the ions K+, Cl-, and Ca2+ play a key role in the RVD process. We observed that these pivotal ions could result in novel RVD behaviors under repeatedly hypotonic stimulation. However, there is a lack of valid means for assessing the effect of pivotal ions on RVD. In this work, we proposed an effective measurement process based on a quartz crystal microbalance (QCM) combined with cell function of RVD for revealing acute variations in cell volume regulation induced by the pivotal ions. A QCM sensor was implemented by adhering MCF-7 cells to a poly-l-lysine-modified gold chip and cyclic stimulation with hypotonic NaCl medium, in which a frequency shift (Δf) showed the superior feasibility of the technique in exhibiting RVD behaviors. With the increase in the number of cycles, the RVD values decreased progressively under three stimulation cycles with hypotonic NaCl alone. Compared with the first cycle, the RVD level in the second and third cycles declined by 60.7±1.7% and 82.1±1.6% (n=3), respectively; conversely, it recovered in NaCl-KCl solution, but was significantly enhanced by 52.2±0.8% in NaCl-CaCl2 solution. Moreover, the inhibition of chloride channels to block Cl- efflux also decreased the RVD level by 56.2±3.0%. The results indicate that these ions (K+, Cl-, Ca2+) are all able to affect the function of RVD, among which intracellular Cl- depletion reduced RVD during measurement, but which recovered with K+ supplement, and Ca2+ enhanced RVD due to activation of ion channels. Therefore, this work provides a comprehensive assessment of cellular behavior and offers an innovative method for gaining insight into cellular functions and mechanisms. A novel strategy was conducted by integrating a quartz crystal microbalance (QCM) with the function of cell volume regulation for analyzing the role of the pivotal ions ( K+, Cl-, Ca2+) in NaCl media on the behaviors of regulatory cell volume decrease (RVD).

Ratiometric ECL sensor based on Apt-AuNS@Lu nanoprobe for analyzing cell swelling-induced ATP release.

A novel ratiometric electrochemiluminescence (ECL) system based on gold nanostars (AuNSs) support was constructed for the determination of hypotonicity-induced ATP release from HepG2 cells. AuNS@Lu nanoprobe was used as anodic luminophore and K2S2O8 as cathodic luminophore as well as anodic co-reactant. AuNS with the large specific surface was adopted to adsorb plentiful luminol to form solid-state probe and as affinity support to immobilize ATP aptamer (Apt). The obtained nanocomposite (Apt-AuNS@Lu) generated a strong ECL signal at + 0.4 V (vs. Ag/AgCl) with co-reactant K2S2O8, because of excellent conductivity and catalytic activity of AuNS. Furthermore, graphene oxide was reduced onto indium tin oxide (ITO) electrodes to facilitate the electron transfer. Following, polydopamine (PDA) film was formed via self-polymerization, improving stability and adhesion of the electrode surface. To immobilize ATP capture aptamer (AptC), abounding AuNSs were attached to RGO/PDA surface. When the sensor was incubated in the mixture solution of Apt-AuNS@Lu and target ATP, the ECL signal of Apt-AuNS@Lu increased with the increase of ATP concentration, meanwhile, the signal of K2S2O8 declined. The ratio of the two luminophores was used for the quantitative determination of ATP. The linear range was 5 to 250 nM, and the limit of detection was 1.4 nM at (3σ)/S. The method was successfully applied to analyze ATP release from HepG2 cells stimulated by 0.45% NaCl hypotonic solution. The results showed that the release kinetics profile of ATP had a sigmoidal shape with rapid release within 10 min and then slowed. Compared to the isotonic groups, the intracellular ATP concentration was 3.7 ± 0.3 µM (n = 3) decreasing by 40.3% and the extracellular was 23.4 ± 1.2 nM (n = 3) increasing by 9.2 times in the hypotonicity for 10 min, which showed ATP release from cells and good agreement with commercial ELISA test. The proposed strategy would be beneficial to broadening application of ECL technology in studying cell biological functions.

Real-Time Monitoring of the Regulatory Volume Decrease of Cancer Cells: A Model for the Evaluation of Cell Migration.

Cell migration plays a vital role in carcinoma invasion and metastasis. Cell regulatory volume decrease (RVD), a mechanism of adjusting cell volume, is a basic physiological function of cells, which is closely related to cell migration. In this work, a quartz crystal microbalance (QCM) cytosensor was first developed for real-time monitoring of cell RVD to evaluate the migration of human breast cancer cells. While stimulating the immobilized cells on the chip with hypotonic solutions, the temporal dynamics of RVD can be tracked by QCM sensor via analyzing frequency shifts during the cell swelling and shrinkage. The results showed that, due to the difference in cell migration capability, the level of RVD for MCF-7 cells and MDA-MB-231 cells was 32.8 ± 2.9% and 49.7 ± 4.2% ( n = 3), respectively. Furthermore, tamoxifen, a chloride channel blocker, was used to suppress cell RVD, indicating concentration dependence and inhibition difference in both types of cells. Combining QCM measurement with cell migration assay, the results showed that the blockage of RVD was positively correlated to the inhibition of cell migration with tamoxifen concentration ranging from 5 to 60 µM, which revealed the relation between cell RVD and cell migration. The study provided a noninvasive and real-time strategy for monitoring cell RVD as well as assessing cell migration, which was expected to supply a new diagnostic tool for metastatic cancers.

Full-color emissive carbon-dots targeting cell walls of onion for in situ imaging of heavy metal pollution.

Plant cell walls (CWs) with complex macromolecular structures can surround and protect cells from a variety of harsh environmental conditions such as pathogens, herbivores, and trace metals. Here, a novel strategy for in situ imaging of plant cell walls was developed to evaluate heavy metal pollution via thiolated full-color emissive carbon-dots (F-CDs) targeting Pb(ii)-adsorbed onion cell walls. The thiolated F-CDs with excellent optical properties from red light to blue light were synthesized through a facile electrochemical approach using new precursors of luminol and l-tryptophan and further modified with l-cysteine. Based on a strong covalent interaction of Pb(ii) and thiolated F-CDs, we achieved in situ fluorescence imaging for the Pb(ii) adsorbed on CWs, which showed enhanced red, blue and green multi-color fluorescence (FL) on CWs with increased Pb(ii)-ion content. In contrast, multi-color fluorescence on cytoplasm diminished, attributed to F-CDs targeting and accumulating on the cytoskeleton which thus limited F-CD diffusion into protoplasm. Therefore, in situ fluorescent images for CWs can demonstrate heavy metal contamination degrees in plant cells. This facile and undamaging protocol will be beneficial for investigating heavy metal migration into the protoplast and fast evaluation of food quality and safety.

A quartz crystal microbalance modified with antibody-coated silver nanoparticles acting as mass signal amplifiers for real-time monitoring of three latent tuberculosis infection biomarkers.

A strategy is described for continuous monitoring of multiple latent tuberculosis infection (LTBI) biomarkers, specifically of interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and interleukin-2 (IL-2). Silver nanoparticles acting as mass signal amplifiers were linked to respective antibodies to form mass nanoprobes for increasing the mass loaded on the surface of the quartz crystal microbalance (QCM). This results in enhanced sensitivity. The mass nanoprobes can be oxidatively dissolved by hydrogen peroxide that avoided the steric hindrance caused by the scale effect of mass nanoprobes. This offers the option of signal recovery monitoring. By using this method, IFN-γ, TNF-α and IL-2 can be monitored serially. The frequency shifts caused by TNF-α, IFN-γ and IL-2, respectively, are reversible. Hence, the biomarkers can be continuously quantified. Compared to multichannel QCM sensing, the new method avoids acoustic interference and has a simplified instrumental setup. The assay is simple, accurate, sensitive, and inexpensive. Graphical abstract Silver nanoparticles as the mass signal amplifiers were linked with the antibodies to form mass nanoprobes for enhancing the monitoring sensitivity. With the introduction of H2O2 to dissolve the mass nanoprobes attached on sensing interface, a signal recovery QCM strategy is established for real-time and continuous monitoring of three LTBI biomarkers.

A high precision MUA-spaced single-cell sensor for cellular receptor assay based on bifunctional Au@Cu-PbCQD nanoprobes.

A single-cell sensor with a spatial architecture was firstly fabricated for realizing high precision single-cell analysis using an 11-mercaptoundecanoic acid (MUA)-spaced sensing interface to prop up single cells and provide a suitable space for effective nanoprobe labeling. Mercapto acids (MA) with different carbon chain lengths were optimized and MUA was selected to provide optimal interspace on the electrodeposited PANI/AuNP substrates, and its carboxyl could couple with folic acid to capture cancer cells. Bifunctional Au@Cu-PbCQD nanoprobes, in which the AuNP cores were linked with lead-coadsorbed carbon quantum dots (PbCQDs) by a copper(ii) ion bridge, were firstly synthesized and applied as highly sensitive electrochemiluminescence (ECL) probes and electrochemical probes. Hyaluronic acid (HA)-functionalized Au@Cu-PbCQD nanoprobes were labelled on MCF-7 cells via specific recognition to the CD44 receptor, which served as the research model. The ECL response of the sensor was applied to evaluate the validity of nanoprobe labeling. With MUA modified, the sensor was able to enhance the ECL intensity by 37.5 ± 3.9%, indicating the remarkable amelioration of the accuracy of single-cell analysis. To take advantage of the bifunctional nanoprobes, differential pulse voltammetry (DPV) was further applied to confirm the feasibility of the proposed single-cell sensor with a spatial architecture. Therefore, the novel strategy provides a single-cell analysis platform to acquire high-precision analytical results, and more accurately to elucidate cellular heterogeneity and biological function.

Real-time quartz crystal microbalance cytosensor based on a signal recovery strategy for in-situ and continuous monitoring of multiple cell membrane glycoproteins.

A real-time quartz crystal microbalance (QCM) cytosensor based on a signal recovery strategy was first developed for in-situ and continuous monitoring of multiple cell membrane glycoproteins. In this work, gold nanoparticles (AuNPs) were linked with ligands to fabricate ligand-functionalized mass nanoprobes with signal amplification for increasing monitoring sensitivity. The mass nanoprobes bound to cell surface could be eluted with glycine-hydrochloric acid buffer, which led to a quick recovery of resonance frequency. Using the strategy, folate receptors (FR), CD44 molecule and epidermal growth factor receptor (EGFR) on cell membrane as the models were monitored continuously. The quantification result of MDA-MB-231 cells showed a range of linearity of 3.0 × 104 to 1.0 × 106 cells and a detection limit of 5.0 × 103 cells. Furthermore, the multianalyte cytosensor exhibited three sensitive and recoverable frequency shifts during continuous monitoring for in-situ and continuous evaluation of the expression levels of FR, CD44 and EGFR on cell membrane, which exhibited that the average numbers of molecules of FR, CD44 and EGFR per MDA-MB-231 cell were 0.5 × 106, 0.2 × 106 and 1.4 × 105 with the relative standard deviation of 4.8%, 4.5% and 5.1%, respectively. Compared with monolithic multichannel QCM, the multianalyte cytosensor based on a single microbalance could not only exclude acoustic interference but also reduce instrumental cost. This work provided a simple and efficient QCM cytosensor for in-situ and continuous monitoring of multiple cell membrane glycoproteins that offered a new avenue for early diagnosis of cancer.

A single-cell analysis platform for electrochemiluminescent detection of platelets adhesion to endothelial cells based on Au@DL-ZnCQDs nanoprobes.

A novel single-cell analysis platform (SCA) was developed for the investigation of platelets adhesion to single human umbilical vein endothelial cell (HUVEC) via using the adhesion molecule (E-selectin) on the damaged HUVEC as the marker site, and integrating electrochemiluminescence (ECL) with the ultrasensitive Au@DL-ZnCQDs nanoprobes. The Au@DL-ZnCQDs nanocomposite, a kind of double layer zinc-coadsorbed carbon quantum dot (ZnCQDs) core-shell nanoprobe, was firstly constructed by using gold nanoparticles (AuNPs) as the core to load with ZnCQDs and then the citrate-modified silver nanoparticles (AgNPs) as the bridge to link AuNPs-ZnCQDs with ZnCQDs to form the core-shell with double layer ZnCQDs (DL-ZnCQDs) nanoprobe, revealed a 10-fold signal amplification. The H2O2-induced oxidative damage HUVECs were utilized as the cellular model on which anti-E-selectin functionalized nanoprobes specially recognized E-selectin, the SCA showed that the ECL signals decreased with platelets adhesion to single HUVEC. The proposed SCA could effectively and dynamically monitor the adhesion between single HUVEC and platelets in the absence and presence of collagen activation, moreover, be able to quantitatively detect the number of platelets adhesion to single HUVEC, and show a good analytical performance with linear range from 1 to 15 platelets. In contrast, the HUVEC was down-regulated the expression of adhesion molecules by treating with quercetin inhibitor, and the SCA also exhibited the feasibility for analysis of platelets adhesion to single HUVEC. Therefore, the single-cell analysis platform provided a novel and promising protocol for analysis of the single intercellular adhesion, and it will be beneficial to elucidate the pathogenesis of cardiovascular diseases.

EGFR-targeting PLGA-PEG nanoparticles as a curcumin delivery system for breast cancer therapy.

Poor bioavailability and non-specificity of chemotherapeutic agents are major challenges in breast cancer treatment. Antibodies and small molecules that block cell signaling pathways have shown promise in the clinic, but their application is also limited by the high costs and treatment dosages required. Novel therapies that aim to rapidly and specifically target malignant cells with long-lasting impact in the tumor microenvironment may ultimately improve clinical outcome in cancer patients. Here, we demonstrate that epidermal growth factor receptor (EGFR)-targeting GE11 peptides conjugated with PEGylated polylactic-co-glycolic acid (PLGA) nanoparticles can be used to effectively deliver an anti-cancer agent, curcumin, into EGFR-expressing MCF-7 cells in vitro and in vivo. Treatment of breast cancer cells and tumor-bearing mice with these curcumin-loaded nanoparticles gave rise to reduced phosphoinositide 3-kinase signaling, decreased cancer cell viability, attenuated drug clearance from the circulation, and suppressed tumor burden compared with free curcumin or non-EGFR targeting nanoparticles. The targeted nanoscale drug delivery system we describe here may provide a new strategy for the design of targeted cancer therapy vectors. Our study provides evidence that the efficacy of pharmacologic anti-cancer agents can be enhanced through their delivery in the form of modified nanoparticles that effectively target specific malignant cell types.

GE11 peptide conjugated selenium nanoparticles for EGFR targeted oridonin delivery to achieve enhanced anticancer efficacy by inhibiting EGFR-mediated PI3K/AKT and Ras/Raf/MEK/ERK pathways.

Selenium nanoparticles (Se NPs) have attracted increasing interest in recent decades because of their anticancer, immunoregulation, and drug carrier functions. In this study, GE11 peptide-conjugated Se NPs (GE11-Se NPs), a nanosystem targeting EGFR over-expressed cancer cells, were synthesized for oridonin delivery to achieve enhanced anticancer efficacy. Oridonin loaded and GE11 peptide conjugated Se NPs (GE11-Ori-Se NPs) were found to show enhanced cellular uptake in cancer cells, which resulted in enhanced cancer inhibition against cancer cells and reduced toxicity against normal cells. After accumulation into the lysosomes of cancer cells and increase of oridonin release under acid condition, GE11-Ori-Se NPs were further transported into cytoplasm after the damage of lysosomal membrane integrity. GE11-Ori-Se NPs were found to induce cancer cell apoptosis by inducting reactive oxygen species (ROS) production, activating mitochondria-dependent pathway, inhibiting EGFR-mediated PI3K/AKT and inhibiting Ras/Raf/MEK/ERK pathways. GE11-Se NPs were also found to show active targeting effects against the tumor tissue in esophageal cancer bearing mice. And in nude mice xenograft model, GE11-Ori-Se NPs significantly inhibited the tumor growth via inhibition of tumor angiogenesis by reducing the angiogenesis-marker CD31 and activation of the immune system by enhancing IL-2 and TNF-α production. The selenium contents in mice were found to accumulate into liver, tumor, and kidney, but showed no significant toxicity against liver and kidney. This cancer-targeted design of Se NPs provides a new strategy for synergistic treating of cancer with higher efficacy and reduced side effects, introducing GE11-Ori-Se NPs as a candidate for further evaluation as a chemotherapeutic agent for EGFR over-expressed esophageal cancers.

Potential-Resolved Electrochemiluminescence for Simultaneous Determination of Triple Latent Tuberculosis Infection Markers.

A novel electrochemiluminescence (ECL) immunosensor based on the potential-resolved strategy was first developed for simultaneous determination of triple latent tuberculosis infection (LTBI) markers with high sensitivity, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and interleukin (IL)-2. In this work, luminol and self-prepared carbon quantum dots and CdS quantum dots were integrated onto gold nanoparticles and magnetic beads in sequence to fabricate potential-resolved ECL nanoprobes with signal amplification. IFN-γ-antibody (Ab)1, TNF-α-Ab1, and IL-2-Ab1 were separately immobilized on three spatially resolved areas of a patterned indium tin oxide electrode to capture the corresponding LTBI markers, which were further recognized by IFN-γ-Ab2, TNF-α-Ab2, and IL-2-Ab2-functionalized ECL nanoprobes. The binding reaction of antibody-functionalized ECL nanoprobes and the captured LTBI markers will generate three sensitive and potential-resolved ECL signals during one potential scanning, and the ECL intensities reflect the concentrations of IFN-γ, TNF-α, and IL-2 in the range of 1.6-200 pg mL-1. Therefore, the multiplexed ECL immunosensor provided an effective approach for simultaneous detection of triple LTBI markers in human serum, so it will be beneficial to facilitate more accurate and reliable clinical diagnosis for LTBI.

Novel Single-Cell Analysis Platform Based on a Solid-State Zinc-Coadsorbed Carbon Quantum Dots Electrochemiluminescence Probe for the Evaluation of CD44 Expression on Breast Cancer Cells.

A novel single-cell analysis platform was fabricated using solid-state zinc-coadsorbed carbon quantum dot (ZnCQDs) nanocomposites as an electrochemiluminescence (ECL) probe for the detection of breast cancer cells and evaluation of the CD44 expression level. Solid-state ZnCQDs nanocomposite probes were constructed through the attachment of ZnCQDs to gold nanoparticles and then the loading of magnetic beads to amplify the ECL signal, exhibiting a remarkable 120-fold enhancement of the ECL intensity. Hyaluronic acid (HA)-functionalized solid-state probes were used to label a single breast cancer cell by the specific recognition of HA with CD44 on the cell surface, revealing more stable, sensitive, and effective tagging in comparison with the water-soluble CQDs. This strategy exhibited a good analytical performance for the analysis of MDA-MB-231 and MCF-7 single cells with linear range from 1 to 18 and from 1 to 12 cells, respectively. Furthermore, this single-cell analysis platform was used for evaluation of the CD44 expression level of these two cell lines, in which the MDA-MB-231 cells revealed a 2.8-5.2-fold higher CD44 expression level. A total of 20 single cells were analyzed individually, and the distributions of the ECL intensity revealed larger variations, indicating the high cellular heterogeneity of the CD44 expression level on the same cell line. The as-proposed single-cell analysis platform might provide a novel protocol to effectively study the individual cellular function and cellular heterogeneity.

Erythrocytes-based quartz crystal microbalance cytosensor for in situ detection of cell surface sialic acid.

An erythrocytes (RBCs) cytosensor was first fabricated for in situ analysis of sialic acid (SA) on the cell surface based on a quartz crystal microbalance (QCM). RBCs, as a recognition element, were immobilized on a concanavalin A (ConA)-modified gold chip through the specific recognition between ConA and mannose on the cell surface. 4-Aminobenzeneboronic acid (APBA)-functionalized gold nanoparticles (AuNPs/APBA) were used as a signal amplification nanoprobe for labeling SA on the surface of RBCs. Compared to that of APBA, the frequency response of the cytosensor could be significantly enhanced 18-fold by using a AuNPs/APBA nanoprobe. RBCs can be detected in the range of 2.6 × 103 to 7.2 × 106 cells per mL with a detection limit of 1.1 × 103 cells per mL. The proposed cytosensor was further applied to detect the expression level of SA on normal and diabetic RBCs in situ, which showed that the average number of SA expressed on single normal and diabetic RBC surfaces were 2.1 ± 0.2 × 108 and 8.2 ± 0.7 × 107 with a relative standard deviation of 4.3% and 3.6%, respectively. The strategy shows an in situ and high sensitivity method for the quantitative evaluation of SA expression on RBC surface and provides a new alternative methodology to analyze glycan expression at the cell surface.

Novel Electrochemiluminescence-Sensing Platform for the Precise Analysis of Multiple Latent Tuberculosis Infection Markers.

Latent tuberculosis infection (LTBI) is one of the major contributing factors for the high incidence of tuberculosis, and the low contents of LTBI markers in human serum present a great challenge for the diagnosis of LTBI. Here, we reported a novel electrochemiluminescence (ECL)-sensing platform for the precise analysis of multiple LTBI markers, interferon-gamma (IFN-γ) and interleukin (IL)-2. In this approach, self-prepared carbon quantum dots (CQDs) and luminol were integrated onto gold nanoparticles (AuNPs), which were further enriched on the surface of magnetic bead (MB) to create two solid-phase ECL nanoprobes (MB@Au@CQDs and MB@Au@luminol) for improving the detection sensitivity efficiently. Graphene oxide (GO) and AuNPs were electrodeposited onto a patterned indium tin oxide (ITO) electrode with two spatially resolved areas in sequence to form two sensitive and stable sensing areas. IFN-γ-antibody (Ab)1 and IL-2-Ab1 were separately immobilized on the two sensing areas to capture the corresponding LTBI markers, which were further recognized by IFN-γ-Ab2 and IL-2-Ab2 labeled as MB@Au@CQDs and MB@Au@luminol. The ECL intensity depended linearly on the content of IFN-γ and IL-2 in the range of 0.01-1000 pg mL-1, with a low detection limit of 10 fg mL-1. The proposed ECL-sensing platform is simple, sensitive, accurate, reliable, and specific to the detection of rare IFN-γ and IL-2 in human serum and provides a valuable protocol for facilitating fast and precise diagnosis of LTBI.