Passive Focusing of Single Cells Using Microwell Arrays for High-Accuracy Image-Activated Sorting.

Sorting single cells from a population was of critical importance in areas such as cell line development and cell therapy. Image-based sorting is becoming a promising technique for the nonlabeling isolation of cells due to the capability of providing the details of cell morphology. This study reported the focusing of cells using microwell arrays and the following automatic size sorting based on the real-time recognition of cells. The simulation first demonstrated the converged streamlines to the symmetrical plane contributed to the focusing effect. Then, the influence of connecting microchannel, flowing length, particle size, and the sample flow rate on the focusing effect was experimentally analyzed. Both microspheres and cells could be aligned in a straight line at the Reynolds number (Re) of 0.027-0.187 and 0.027-0.08, respectively. The connecting channel was proved to drastically improve the focusing performance. Afterward, a tapered microwell array was utilized to focus sphere/cell spreading in a wide channel to a straight line. Finally, a custom algorithm was employed to identify and sort the size of microspheres/K562 cells with a throughput of 1 event/s and an accuracy of 97.8/97.1%. The proposed technique aligned cells to a straight line at low Reynolds numbers and greatly facilitated the image-activated sorting without the need for a high-speed camera or flow control components with high frequency. Therefore, it is of enormous application potential in the field of nonlabeled separation of single cells.

A tempo-spatial controllable microfluidic shear-stress generator for in-vitro mimicking of the thrombus.

Pathological conditions linked to shear stress have been identified in hematological diseases, cardiovascular diseases, and cancer. These conditions often exhibit significantly elevated shear stress levels, surpassing 1000 dyn/cm2 in severely stenotic arteries. Heightened shear stress can induce mechanical harm to endothelial cells, potentially leading to bleeding and fatal consequences. However, current technology still grapples with limitations, including inadequate flexibility in simulating bodily shear stress environments, limited range of shear stress generation, and spatial and temporal adaptability. Consequently, a comprehensive understanding of the mechanisms underlying the impact of shear stress on physiological and pathological conditions, like thrombosis, remains inadequate. To address these limitations, this study presents a microfluidic-based shear stress generation chip as a proposed solution. The chip achieves a substantial 929-fold variation in shear stress solely by adjusting the degree of constriction in branch channels after PDMS fabrication. Experiments demonstrated that a rapid increase in shear stress up to 1000 dyn/cm2 significantly detached 88.2% cells from the substrate. Long-term exposure (24 h) to shear stress levels below 8.3 dyn/cm2 did not significantly impact cell growth. Furthermore, cells exposed to shear stress levels equal to or greater than 8.3 dyn/cm2 exhibited significant alterations in aspect ratio and orientation, following a normal distribution. This microfluidic chip provides a reliable tool for investigating cellular responses to the wide-ranging shear stress existing in both physiological and pathological flow conditions.

Smart Droplet Microfluidic System for Single-Cell Selective Lysis and Real-Time Sorting Based on Microinjection and Image Recognition.

Single-cell analysis has important implications for understanding the specificity of cells. To analyze the specificity of rare cells in complex blood and biopsy samples, selective lysis of target single cells is pivotal but difficult. Microfluidics, particularly droplet microfluidics, has emerged as a promising tool for single-cell analysis. In this paper, we present a smart droplet microfluidic system that allows for single-cell selective lysis and real-time sorting, aided by the techniques of microinjection and image recognition. A custom program evolved from Python is proposed for recognizing target droplets and single cells, which also coordinates the operation of various parts in a whole microfluidic system. We have systematically investigated the effects of voltage and injection pressure applied to the oil-water interface on droplet microinjection. An efficient and selective droplet injection scheme with image feedback has been demonstrated, with an efficiency increased dramatically from 2.5% to about 100%. Furthermore, we have proven that the cell lysis solution can be selectively injected into target single-cell droplets. Then these droplets are shifted into the sorting area, with an efficiency for single K562 cells reaching up to 73%. The system function is finally explored by introducing complex cell samples, namely, K562 cells and HUVECs, with a success rate of 75.2% in treating K562 cells as targets. This system enables automated single-cell selective lysis without the need for manual handling and sheds new light on the cooperation with other detection techniques for a broad range of single-cell analysis.

Dual-Modal Apoptosis Assay Enabling Dynamic Visualization of ATP and Reactive Oxygen Species in Living Cells.

ATP and reactive oxygen species (ROS) are considered significant indicators of cell apoptosis. However, visualizing the interplay between apoptosis-related ATP and ROS is challenging. Herein, we developed a metal-organic framework (MOF)-based nanoprobe for an apoptosis assay using duplex imaging of cellular ATP and ROS. The nanoprobe was fabricated through controlled encapsulation of gold nanorods with a thin zirconium-based MOF layer, followed by modification of the ROS-responsive molecules 2-mercaptohydroquinone and 6-carboxyfluorescein-labeled ATP aptamer. The nanoprobe enables ATP and ROS visualization via fluorescence and surface-enhanced Raman spectroscopy, respectively, avoiding the mutual interference that often occurs in single-mode methods. Moreover, the dual-modal assay effectively showed dynamic imaging of ATP and ROS in cancer cells treated with various drugs, revealing their apoptosis-related pathways and interactions that differ from those under normal conditions. This study provides a method for studying the relationship between energy metabolism and redox homeostasis in cell apoptosis processes.

Downregulation of DDIT4 ameliorates abnormal behaviors in autism by inhibiting ferroptosis via the PI3K/Akt pathway.

Autism spectrum disorder (ASD) is a complex disease with unclear etiology. Studies have shown that ferroptosis is also related to ASD progression, but the specific mechanism is still unclear. Valproic acid (VPA) induced neuronal ferroptosis in vitro. Mechanistic studies showed that both VPA and ferroptosis inducers promoted the expression of DDIT4 in neurons, thereby inhibiting the activation of the PI3K/Akt pathway. DDIT4 increased the accumulation of ROS, MDA and Fe2+, inhibited neuronal viability and downregulated GPX4 expression by inactivating the PI3K/Akt pathway. Ferroptosis inhibitors reversed the anti-survival effect of DDIT4, indicating that DDIT4 enhances ferroptosis through the PI3K/Akt pathway, thereby inhibiting neuronal viability. Further in vivo experiments found that autistic mice had high levels of ROS, MDA and Fe2+, increased DDIT4 expression, and downregulated expression levels of GPX4, p-PI3K and p-Akt; after downregulation of DDIT4 expression, the accumulation of ROS, MDA and Fe2+ was significantly reduced, while the expression levels of GPX4, p-PI3K and p-Akt were upregulated, indicating that DDIT4 knockdown reduces ferroptosis in autistic mice. In addition, DDIT4 downregulation, PI3K/Akt pathway activation, and ferroptosis inhibitors all improved social behavior deficits, repetitive stereotyped and compulsive behaviors, anxiety and exploratory behaviors in autistic mice, but PI3K/Akt pathway inhibitors significantly blocked the rescue of abnormal behaviors by DDIT4 downregulation in autistic mice. Therefore, downregulation of DDIT4 expression ameliorates abnormal behaviors in autism by inhibiting ferroptosis via the PI3K/Akt pathway, indicating that DDIT4, the PI3K/Akt pathway and ferroptosis have key roles in autism.

Screening of Therapeutic Targets for Pancreatic Cancer by Bioinformatics Methods.

Pancreatic cancer (PC) has the lowest survival rate and the highest mortality rate among all cancers due to lack of effective treatments. The objective of the current study was to identify potential therapeutic targets in PC. Three transcriptome datasets, namely GSE62452, GSE46234, and GSE101448, were analyzed for differentially expressed genes (DEGs) between cancer and normal samples. Several bioinformatics methods, including functional analysis, pathway enrichment, hub genes, and drugs were used to screen therapeutic targets for PC. Fisher's exact test was used to analyze functional enrichments. To screen DEGs, the paired t-test was employed. The statistical significance was considered at p <0.05. Overall, 60 DEGs were detected. Functional enrichment analysis revealed enrichment of the DEGs in "multicellular organismal process", "metabolic process", "cell communication", and "enzyme regulator activity". Pathway analysis demonstrated that the DEGs were primarily related to "Glycolipid metabolism", "ECM-receptor interaction", and "pathways in cancer". Five hub genes were examined using the protein-protein interaction (PPI) network. Among these hub genes, 10 known drugs targeted to the CPA1 gene and CLPS gene were found. Overall, CPA1 and CLPS genes, as well as candidate drugs, may be useful for PC in the future.

Schiff Base Reaction in a Living Cell: In Situ Synthesis of a Hollow Covalent Organic Polymer To Regulate Biological Functions.

Artificially performing chemical reactions in living biosystems to attain various physiological aims remains an intriguing but very challenging task. In this study, the Schiff base reaction was conducted in cells using Sc(OTf)3 as a catalyst, enabling the in situ synthesis of a hollow covalent organic polymer (HCOP) without external stimuli. The reversible Schiff base reaction mediated intracellular Oswald ripening endows the HCOP with a spherical, hollow porous structure and a large specific surface area. The intracellularly generated HCOP reduced cellular motility by restraining actin polymerization, which consequently induced mitochondrial deactivation, apoptosis, and necroptosis. The presented intracellular synthesis system inspired by the Schiff base reaction has strong potential to regulate cell fate and biological functions, opening up a new strategic possibility for intervening in cellular behavior.

CDC6 is a prognostic biomarker and correlated with immune infiltrates in glioma.

BACKGROUND: Cell division cycle 6 (CDC6) has been proven to be associated with the initiation and progression of human multiple tumors. However, it's role in glioma, which is ranked as one of the common primary malignant tumor in the central nervous system and is associated with high morbidity and mortality, is unclear. METHODS: In this study, we explored CDC6 gene expression level in pan-cancer. Furthermore, we focused on the relationships between CDC6 expression, its prognostic value, potential biological functions, and immune infiltrates in glioma patients. We also performed vitro experiments to assess the effect of CDC6 expression on proliferative, apoptotic, migrant and invasive abilities of glioma cells. RESULTS: As a result, CDC6 expression was upregulated in multiple types of cancer, including glioma. Moreover, high expression of CDC6 was significantly associated with age, IDH status, 1p/19q codeletion status, WHO grade and histological type in glioma (all p < 0.05). Meanwhile, high CDC6 expression was associated with poor overall survival (OS) in glioma patients, especially in different clinical subgroups. Furthermore, a univariate Cox analysis showed that high CDC6 expression was correlated with poor OS in glioma patients. Functional enrichment analysis indicated that CDC6 was mainly involved in pathways related to DNA transcription and cytokine activity, and Gene Set Enrichment Analysis (GSEA) revealed that MAPK pathway, P53 pathway and NF-κB pathway in cancer were differentially enriched in glioma patients with high CDC6 expression. Single-sample gene set enrichment analysis (ssGSEA) showed CDC6 expression in glioma was positively correlated with Th2 cells, Macrophages and Eosinophils, and negative correlations with plasmacytoid dendritic cells, CD8 T cells and NK CD56bright cells, suggesting its role in regulating tumor immunity. Finally, CCK8 assay, flow cytometry and transwell assays showed that silencing CDC6 could significantly inhibit proliferation, migration, invasion, and promoted apoptosis of U87 cells and U251 cells (p < 0.05). CONCLUSION: In conclusion, high CDC6 expression may serve as a promising biomarker for prognosis and correlated with immune infiltrates, presenting to be a potential immune therapy target in glioma.

AuNPs-COFs Core-Shell Reversible SERS Nanosensor for Monitoring Intracellular Redox Dynamics.

The redox homeostasis in living cells is greatly crucial for maintaining the redox biological function, whereas accurate and dynamic detection of intracellular redox states still remains challenging. Herein, a reversible surface-enhanced Raman scattering (SERS) nanosensor based on covalent organic frameworks (COFs) was prepared to dynamically monitor the redox processes in living cells. The nanosensor was fabricated by modifying the redox-responsive Raman reporter molecule, 2-Mercaptobenzoquione (2-MBQ), on the surface of gold nanoparticles (AuNPs), followed by the in situ coating of COFs shell. 2-MBQ molecules can repeatedly and quickly undergo reduction and oxidation when successively treated with ascorbic acid (AA) and hypochlorite (ClO-) (as models of reductive and oxidative species, respectively), which resulted in the reciprocating changes of SERS spectra at 900 cm-1. The construction of the COFs shell provided the nanosensor with great stability and anti-interference capability, thus reliably visualizing the dynamics of intracellular redox species like AA and ClO- by SERS nanosensor. Taken together, the proposed SERS strategy opens up the prospects to investigate the signal transduction pathways and pathological processes related with redox dynamics.

Generation and Screening of Antigen-Specific Nanobodies from Mammalian Cells Expressing the BCR Repertoire Library Using Droplet-Based Microfluidics.

Nanobodies, also known as VHHs, originate from the serum of Camelidae. Nanobodies have considerable advantages over conventional antibodies, including smaller size, more modifiable, and deeper tissue penetration, making them promising tools for immunotherapy and antibody-drug development. A high-throughput nanobody screening platform is critical to the rapid development of nanobodies. To date, droplet-based microfluidic systems have exhibited improved performance compared to the traditional phage display technology in terms of time and throughput. In realistic situations, however, it is difficult to directly apply the technology to the screening of nanobodies. Requirements of plasma cell enrichment and high cell viability, as well as a lack of related commercial reagents, are leading causes for impeding the development of novel methods. We overcame these obstacles by constructing a eukaryotic display system that secretes nanobodies utilizing homologous recombination and eukaryotic transformation technologies, and the significant advantages are that it is independent of primary cell viability and it does not require plasma cell enrichment in advance. Next, a signal capture system of "SA-beads + Biotin-antigen + nanobody-6 × His + fluorescence-labeled anti-6 × His (secondary antibody)" was designed for precise localization of the eukaryotic-expressed nanobodies in a droplet. Based on this innovation, we screened 293T cells expressing anti-PD-L1 nanobodies with a high positive rate of targeted cells (up to 99.8%). Then, single-cell transcriptomic profiling uncovered the intercellular heterogeneity and BCR sequence of target cells at a single-cell level. The complete complementarity determining region (CDR3) structure was obtained, which was totally consistent with the BCR reference. This study expanded the linkage between microfluidic technology and nanobody applications and also showed potential to accelerate the rapid transformation of nanobodies in the large-scale market.

A Ti3 C2 TX /Pt-Pd based amperometric biosensor for sensitive cancer biomarker detection.

The detection of cancer biomarkers is of great significance for the early screening of cancer. Detecting the content of sarcosine in blood or urine has been considered to provide a basis for the diagnosis of prostate cancer. However, it still lacks simple, high-precision and wide-ranging sarcosine detection methods. In this work, a Ti3 C2 TX /Pt-Pd nanocomposite with high stability and excellent electrochemical performance has been synthesized by a facile one-step alcohol reduction and then used on a glassy carbon electrode (GCE) with sarcosine oxidase (SOx ) to form a sarcosine biosensor (GCE/Ti3 C2 TX /Pt-Pd/SOx ). The prominent electrocatalytic activity and biocompatibility of Ti3 C2 TX /Pt-Pd enable the SOx to be highly active and sensitive to sarcosine. Under the optimized conditions, the prepared biosensor has a wide linear detection range to sarcosine from 1 to 1000 µM with a low limit of detection of 0.16 µM (S/N = 3) and a sensitivity of 84.1 µA/mM cm2 . Besides, the reliable response in serum samples shows its potential in the early diagnosis of prostate cancer. More importantly, the successful construction and application of the amperometric biosensor based on Ti3 C2 TX /Pt-Pd will provide a meaningful reference for detecting other cancer biomarkers.

A miniature CuO nanoarray sensor for noninvasive detection of trace salivary glucose.

An ultrasensitive mini-sensor has been developed for nonenzymatic and noninvasive determination of trace glucose in saliva. The miniature detector exhibits ultra-high sensitivity and resolution at very low glucose concentration owing to the excellent electrocatalytic activity and electron transfer rate of the prepared 3D ordered CuO nanoflake array in-situ grown on a copper foil. The structure and morphology of the cupric oxide nanoarray were characterized by X-ray powder diffraction and scanning electron microscopy. The electrocatalysis of the CuO nanoarray modified electrode to glucose was demonstrated by cyclic voltammetry and chronoamperometry. The modified electrode presents a high sensitivity of 4954 µA mM-1 cm-2 to glucose at + 0.55 V with a wide linear range of 1.0 µmol/L to 6000 µmol/L and a low detection limit of 0.1 µmol/L and long-term stability. Furthermore, the mini-sensor can clearly distinguish diabetics from healthy people because of its excellent sensing performance. The developed miniaturized sensor holds the prospect for noninvasive determination of trace glucose in saliva for diabetic patients.

Deep Learning-Based Spectral Extraction for Improving the Performance of Surface-Enhanced Raman Spectroscopy Analysis on Multiplexed Identification and Quantitation.

Surface-enhanced Raman spectroscopy (SERS) has been recognized as a promising analytical technique for its capability of providing molecular fingerprint information and avoiding interference of water. Nevertheless, direct SERS detection of complicated samples without pretreatment to achieve the high-efficiency identification and quantitation in a multiplexed way is still a challenge. In this study, a novel spectral extraction neural network (SENN) model was proposed for synchronous SERS detection of each component in mixed solutions using a demonstration sample containing diquat dibromide (DDM), methyl viologen dichloride (MVD), and tetramethylthiuram disulfide (TMTD). A SERS spectra dataset including 3600 spectra of DDM, MVD, TMTD, and their mixtures was first constructed to train the SENN model. After the training step, the cosine similarity of the SENN model can achieve 0.999, 0.997, and 0.994 for DDM, MVD, and TMTD, respectively, which means that the spectra extracted from the mixture are highly consistent with those collected by the SERS experiment of the corresponding pure samples. Furthermore, a convolutional neural network model for quantitative analysis is combined with the SENN, which can simultaneously and rapidly realize the qualitative and quantitative SERS analysis of mixture solutions with lower than 8.8% relative standard deviation. The result demonstrates that the proposed strategy has great potential in improving SERS analysis in environmental monitoring, food safety, and so on.

Feeling like the sky is falling down: Experiences of parents of adolescents diagnosed with cancer in one-child families in China - A qualitative study.

BACKGROUND: As a result of the one-child policy of 1979, today there are numerous one-child families with adolescents in Mainland China. Little is known about the experiences of parents of such adolescents diagnosed with cancer. OBJECTIVES: This study explored the experiences of parents whose adolescent child was diagnosed with cancer in one-child families in China. METHODS: A qualitative methodology based on hermeneutic phenomenology was employed. The participants were parents of adolescent cancer patients in one-child families. Data were collected using in-depth semi-structured interviews and analysed using van Manen's hermeneutic phenomenological approach. The COREQ checklist was used for this study. RESULTS: Fourteen parents (eleven mothers, three fathers) participated in the study. One overarching theme emerged: feeling like the sky is falling down. In addition, there were five related themes: self-condemnation; 'white lies' - that is, difficulty in telling the truth; struggling with a sense of collapse; fear of losing the child and hopelessness. Almost all the participants experienced insomnia after learning about the diagnosis. In a few cases, hopelessness-induced suicidal ideation or even suicidal behaviour. CONCLUSIONS: Parents of adolescents diagnosed with cancer in one-child families in China experienced extremely painful emotions. The truth about their child's condition not only caused immense psychological trauma but also induced pessimism about their own future. IMPLICATIONS FOR CLINICAL PRACTICE: The experiences of parents in one-child families where an adolescent child has been diagnosed with cancer should be taken seriously. In addition, support should be provided to help parents maintain a normal life and feel hopeful for their future.

In Situ Monitoring of Hydrogen Peroxide Released from Living Cells Using a ZIF-8-Based Surface-Enhanced Raman Scattering Sensor.

Hydrogen peroxide (H2O2) widely involves in intracellular and intercellular redox signaling pathways, playing a vital role in regulating various physiological events. Nevertheless, current analytical methods for the H2O2 assay are often hindered by relatively long response time, low sensitivity, or self-interference. Herein, a zeolitic imidazolate framework-8 (ZIF-8)-based surface-enhanced Raman scattering (SERS) sensor has been developed to detect H2O2 released from living cells by depositing ZIF-8 over SERS active gold nanoparticles (AuNPs) grafted with H2O2-responsive probe molecules, 2-mercaptohydroquinone. Combining the superior fingerprint identification of SERS and the highly efficient enrichment and selective response of H2O2 by ZIF, the ZIF-8-based SERS sensor exhibits a high anti-interference ability for H2O2 detection, with a limit of detection as low as 0.357 nM. Satisfyingly, owing to the enhanced catalytic activity derived from the successful integration of AuNPs and ZIF, the response time as short as 1 min can be obtained, demonstrating the effectiveness of the SERS sensor for rapid H2O2 detection. Furthermore, the developed SERS sensor enables real-time detection of H2O2 secreted from living cells under phorbol myristate acetate stimulation, as cells can be cultured on-chip. This study will pave the way toward the development of a metal-organic framework-based SERS platform for application in the fields of biosensing and early disease diagnosis associated with H2O2 secretion, thus exhibiting promising potential for future therapies.

Comparing the 7th and 8th editions of UICC/AJCC staging system for nasopharyngeal carcinoma in the IMRT era.

BACKGROUND: To compare the prognostic value of 7th and 8th editions of the Union for International Cancer Control/American Joint Committee on Cancer (UICC/AJCC) staging system for patients with nonmetastatic nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy and simultaneous integrated boost- intensity-modulated radiation therapy (SIB-IMRT). METHODS: Patients with NPC (n = 300) who received SIB-IMRT were included. Survival by T-classification, N-classification, and stage group of each staging system was assessed. RESULTS: For T-classification, nonsignificant difference was observed between T1 and T3 and between T2 and T3 disease (P = 0.066 and 0.106, respectively) for overall survival (OS) in the 7th staging system, whereas all these differences were significant in the 8th staging system (all P < 0.05). The survival curves for disease-free survival (DFS) and locoregional recurrence-free survival (LRRFS) in both staging systems were similar, except for the comparison of T2 and T4 disease for LRRFS (P = 0.070 for 7th edition; P = 0.011 for 8th edition). For N-classification, significant differences were observed between N2 and N3 diseases after revision (P = 0.046 and P = 0.043 for OS and DFS, respectively). For staging system, no significant difference was observed between IVA and IVB of 7th edition. CONCLUSION: The 8th AJCC staging system appeared to have superior prognosis value in the SIB-IMRT era compared with the 7th edition.

Rapid detection of carbamate pesticide residues using microchip electrophoresis combining amperometric detection.

The long-term consumption of food with pesticide residues has harmful effects on human health and the demand for pesticide detection technology tends to be miniaturized and instant. To this end, we demonstrated the first application of indirectly detecting two carbamate pesticides, metolcarb and carbaryl, by gold nanoparticle-modified indium tin oxide electrode in dual-channel microchip electrophoresis and amperometric detection (ME-AD) system. m-Cresol and α-naphthol were obtained after pesticide hydrolysis in alkaline solution, and then separated and detected by ME-AD. Parameters including the detection potential and running buffer concentration and pH were optimized to improve the detection sensitivity and separation efficiency. Under the optimal conditions, the two analytes were completely separated within 80 s. m-Cresol and α-naphthol presented a wide linear range from 1 to 100 µM, with limits of detection of 0.16 µM and 0.34 µM, respectively (S/N = 3). Moreover, the reliability of this system was demonstrated by analyzing metolcarb and carbaryl in spiked vegetable samples.

[Wolffian Adnexal Tumor:Report of One Case].

This article reports a patient who suffered from Wolffian adnexal tumor.We also briefly elucidate the pathogenesis,clinicopathological features,diagnosis,differentiation,and treatment of Wolffian adnexal tumor,with an attempt to increase the awareness of the disease and reduce misdiagnosis.

Novel Wax Valves To Improve Distance-Based Analyte Detection in Paper Microfluidics.

Microfluidic paper-based analytical devices (µPADs) have been extensively studied for disease diagnostics, food quality control, and environmental monitoring due to the advantages of low cost, portability, and simplicity. The lack of flow controllability has triggered the development of valves for such devices. This paper reports the µPADs integrating novel wax valves for distance-based detection. The valves are printed on paper and can be manually opened by organic solvents within seconds. The opened valve does not influence the flow. The µPADs with wax valves were then applied in the distance-based detection of potassium iodate and glucose. The valves allow mixing of reagents and subsequent incubation in the loading zone, resulting in a shorter detection time and larger linear detection range. This study has demonstrated a linear detection range of 0.05-0.5 mM for potassium iodate, while linear ranges of 1-5 and 2.5-80 mg/dL are achieved for glucose when total detection time is 15 and 25 min, respectively. The lower detection limit is only 1/11 of that in a previous study. The detection ranges of iodate and glucose assays cover the concentrations of iodate in salt/milk and glucose in human saliva, respectively. Due to the simplicity, reliability, and ability for high-density integration, the µPADs with wax valves are of great potential in point-of-care (sampling) applications.

A phenylboronate-based SERS nanoprobe for detection and imaging of intracellular peroxynitrite.

A surface-enhanced Raman scattering (SERS) based nanoprobe was developed for detection and imaging of endogenous peroxynitrite in living cells. The probe was fabricated by assembling 3-mercaptophenylboronic acid pinacol ester onto the surface of gold nanoparticles (AuNPs). The detection of peroxynitrite is accomplished via measurement of the changes in the SERS spectra (at 882 cm-1) that are caused by the reaction between probe and peroxynitrite. The probe has a fast response (<30 s), a 0.4 µM lower detection limit and a wide linearity range from 5.0 × 10-7 to 1.0 × 10-4 M. It is biocompatible and highly stable on storage and under various pH conditions. Both the reaction and the SERS signal are highly specific over other species. The nanoprobe was successfully applied to SERS imaging of peroxynitrite that is produced in macrophages under oxidative stress. Conceivably, the method has a most viable tool for use in studies on peroxynitrite-related physiological and pathological processes. Graphical abstract Schematic presentation of surface-enhanced Raman scattering (SERS) nanoprobes fabricated by assembling phenylboronate on gold nanoparticles (AuNPs) for detecting intracellular peroxynitrite (ONOO-) via specific reaction-caused SERS changes.