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With the increasing demand for trace sample analysis, injecting trace samples into liquid chromatography-mass spectrometry (LC-MS) systems with minimal loss has become a major challenge. Herein, we describe an in situ LC-MS analytical probe, the Falcon probe, which integrates multiple functions of high-pressure sample injection without sample loss, high-efficiency LC separation, and electrospray. The main body of the Falcon probe is made of stainless steel and fabricated by the computer numerical control (CNC) technique, which has ultrahigh mechanical strength. By coupling a nanoliter-scale droplet reactor made of polyether ether ketone (PEEK) material, the Falcon probe-based LC-MS system was capable of operating at mobile-phase pressures up to 800 bar, which is comparable to those of conventional ultraperformance liquid chromatography (UPLC) systems. Using the probe pressing microamount in situ (PPMI) injection approach, the Falcon probe-based LC-MS system showed high separation efficiency and good repeatability with relative standard deviations (RSDs) of retention time and peak area of 1.8% and 9.9%, respectively, in peptide mixture analysis (n = 6). We applied this system to the analysis of a trace amount of 200 pg of HeLa protein digest and successfully identified an average of 766 protein groups (n = 5). By combining in situ sample pretreatment at the nanoliter range, we further applied the present system in single-cell proteomic analysis, and 241 protein groups were identified in single 293 cells, which preliminarily demonstrated its potential in the analysis of trace amounts of samples with complex compositions.
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Pressão , Humanos , Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Nanotecnologia , Polietilenoglicóis/química , Peptídeos/análise , Cromatografia Líquida de Alta Pressão , Células HeLa , Benzofenonas/análise , Benzofenonas/química , Polímeros/química , Cetonas/química , Cetonas/análise , Proteômica/métodosRESUMO
Characterizing the profiles of proteome and metabolome at the single-cell level is of great significance in single-cell multiomic studies. Herein, we proposed a novel strategy called one-shot single-cell proteome and metabolome analysis (scPMA) to acquire the proteome and metabolome information in a single-cell individual in one injection of LC-MS/MS analysis. Based on the scPMA strategy, a total workflow was developed to achieve the single-cell capture, nanoliter-scale sample pretreatment, one-shot LC injection and separation of the enzyme-digested peptides and metabolites, and dual-zone MS/MS detection for proteome and metabolome profiling. Benefiting from the scPMA strategy, we realized dual-omic analysis of single tumor cells, including A549, HeLa, and HepG2 cells with 816, 578, and 293 protein groups and 72, 91, and 148 metabolites quantified on average. A single-cell perspective experiment for investigating the doxorubicin-induced antitumor effects in both the proteome and metabolome aspects was also performed.
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Proteoma , Espectrometria de Massas em Tandem , Humanos , Proteoma/metabolismo , Cromatografia Líquida , Metaboloma , Células HeLaRESUMO
The continuing pursuit for a healthy life has led to the urgent need for on-site analysis. In response to the urgent needs of on-site analysis, we propose a novel concept, called lab at home (LAH), for building automated and integrated total analysis systems to perform chemical and biological testing at home. It represents an emerging research area with broad prospects that has not yet attracted sufficient attention. In this paper, we discuss the urgent need, challenges, and future prospects of this area, and the possible roadmap for achieving the goal of LAH has also been proposed.
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The authors would like to call the reader's attention to the fact that unfortunately the name of Jianzhang Pan was missing as co-author of this contribution.
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Digital PCR is a powerful method for absolute nucleic acid quantification with unprecedented accuracy and precision. To promote the wider use and application of digital PCR, several major challenges still exist, including reduction of cost, integration of the instrumental platform, and simplification of operations. This paper describes a reusable microfluidic device that generates nanoliter droplet arrays based on step emulsification for the on-chip multiplex digital PCR of eight samples simultaneously. The device contains two glass plates that can be quickly assembled with prefilled mineral oil. Droplets are simply generated through the arrays of step emulsification nozzles driven by a single pressure controller and are self-assembled into monolayer droplet arrays in U-shaped chambers. The use of mineral oil eliminates bubble generation; thus, no overpressure is required during thermocycling. Moreover, the device can be reused many times after disassembly and a brief cleaning procedure, which significantly reduces the cost of the device per dPCR assays. The device was able to detect template DNA at concentrations as low as 10 copies/µL with a dynamic range of approximately 4 logs. We applied this device in the quantitative assessment of HER2 copy number variation, which is important for targeted therapy and prognosis of breast cancer. The performance was validated by 16 clinical samples, obtaining similar results to commercial digital PCR. We envision that this low-cost, reusable, and user-friendly device can be broadly used in various applications.
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DNA de Neoplasias/análise , Dispositivos Lab-On-A-Chip , Reação em Cadeia da Polimerase Multiplex/métodos , Neoplasias da Mama/genética , Variações do Número de Cópias de DNA , DNA de Neoplasias/genética , Emulsões/química , Vidro/química , Humanos , Técnicas Analíticas Microfluídicas/instrumentação , Técnicas Analíticas Microfluídicas/métodos , Óleo Mineral/química , Reação em Cadeia da Polimerase Multiplex/instrumentação , Receptor ErbB-2/genéticaRESUMO
Here, a compact high-speed CE bioanalyzer based on a short capillary has been developed. Multiple modules of picoliter scale sample injection, high-speed CE separation, sample changing, LIF detection, as well as a custom designed tablet computer for data processing, instrument controlling, and result displaying were integrated in the bioanalyzer with a total size of 23 × 17 × 19 cm (length × width × height). The high-speed CE bioanalyzer is capable of performing automated sample injection and separation for multiple samples and has been successfully applied in fast separations of amino acids, chiral amino acids, proteins and DNA fragments. For instance, baseline separation of six FITC-labeled amino acids and ultrahigh-speed separation of three amino acids could be achieved within 7 and 1 s, respectively. The separation speed and efficiency of the optimized high-speed CE system are comparable to or even better than those reported in microchip-based CE systems. We believe this bioanalyzer could provide an advanced platform for fundamental research in bioscience and clinical diagnosis, as well as in quality control for drugs, foods, and feeds.
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Eletroforese Capilar/instrumentação , Aminoácidos/isolamento & purificação , EstereoisomerismoRESUMO
Fabrication of capillaries with tapered tips is an important technique that is required in many analytical chemistry areas, such as ESI-MS, CE, electrochemical analysis, and microinjection. This paper describes a simple and effective grinding-based fabrication method for capillaries with tapered tips. A novel grinding mode utilizing the combination of rotation and precession of an elastic capillary was developed, which significantly improved the controllability to the grinding process as well as the capillary tip shape. The capillary was fabricated by fixing it in an electric drill installed perpendicularly, and grind the capillary tip rotated around its own axis as well as the drill axis on sandpapers. Compared with conventional fabrication techniques for capillary tips, the present method is easy to control the capillary tip shape in routine laboratories without the requirement of expensive equipments or poisonous reagent (e.g. hydrofluoric acid (HF) solution). Various capillaries with different tip diameters and tip taper angles could be fabricated using the present method with good controllability and reproducibility. These capillaries were applied in high-speed CE and ESI-MS analysis to demonstrate the feasibility and potential of this fabrication method.
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Eletroforese Capilar/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos , Eletroforese Capilar/instrumentaçãoRESUMO
The shotgun proteomic analysis is currently the most promising single-cell protein sequencing technology, however its identification level of ~1000 proteins per cell is still insufficient for practical applications. Here, we develop a pick-up single-cell proteomic analysis (PiSPA) workflow to achieve a deep identification capable of quantifying up to 3000 protein groups in a mammalian cell using the label-free quantitative method. The PiSPA workflow is specially established for single-cell samples mainly based on a nanoliter-scale microfluidic liquid handling robot, capable of achieving single-cell capture, pretreatment and injection under the pick-up operation strategy. Using this customized workflow with remarkable improvement in protein identification, 2449-3500, 2278-3257 and 1621-2904 protein groups are quantified in single A549 cells (n = 37), HeLa cells (n = 44) and U2OS cells (n = 27) under the DIA (MBR) mode, respectively. Benefiting from the flexible cell picking-up ability, we study HeLa cell migration at the single cell proteome level, demonstrating the potential in practical biological research from single-cell insight.
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Proteoma , Proteômica , Animais , Humanos , Células HeLa , Proteômica/métodos , Proteoma/metabolismo , Análise de Célula Única , Fluxo de Trabalho , Mamíferos/metabolismoRESUMO
We performed cell-based drug combination screening using an integrated droplet-based microfluidic system based on the sequential operation droplet array (SODA) technique. In the system, a tapered capillary connected with a syringe pump was used for multistep droplet manipulations. An oil-covered two-dimensional droplet array chip fixed in an x-y-z translation stage was used as the platform for cell culture and analysis. Complex multistep operations for drug combination screening involving long-term cell culture, medium changing, schedule-dependent drug dosage and stimulation, and cell viability testing were achieved in parallel in the semiopen droplet array, using multiple droplet manipulations including liquid metering, aspirating, depositing, mixing, and transferring. Long-term cell culture as long as 11 days was performed in oil-covered 500 nL droplets by changing the culture medium in each droplet every 24 h. The present system was applied in parallel schedule-dependent drug combination screening for A549 nonsmall lung cancer cells with the cell cycle-dependent drug flavopiridol and two anticancer drugs of paclitaxel and 5-fluorouracil. The highest inhibition efficiency was obtained with a schedule combination of 200 nM flavopiridol followed by 100 µM 5-fluorouracil. The drug consumption for each screening test was substantially decreased to 5 ng-5 µg, corresponding to 10-1000-fold reductions compared with traditional drug screening systems with 96-well or 384-well plates. The present work provides a novel and flexible droplet-based microfluidic approach for performing cell-based screening with complex and multistep operation procedures.
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Antineoplásicos/análise , Técnicas Analíticas Microfluídicas/métodos , Antineoplásicos/administração & dosagem , Técnicas de Cultura de Células , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Combinação de Medicamentos , Avaliação Pré-Clínica de Medicamentos/métodos , HumanosRESUMO
On-site nucleic acid testing (NAT) plays an important role for disease monitoring and pathogen diagnosis. In this work, we developed an automated and fully-integrated nucleic acid analyzer by combining the automated liquid handling robot technique with the microfluidic droplet-based real-time PCR assay technique. The present analyzer could achieve multiple operations including sample introduction, nucleic acid extraction based on magnetic solid-phase extraction, reverse transcription and, sample droplet generation, PCR amplification, real-time and dual fluorescence detection of droplet array. A strategy of constructing an integrated compact and low-cost system was adopted to minimize the analyzer size to 50 × 45 × 45 cm (length × width × height), and reduce the instrument cost to ca. $900 with a single analysis cost less than $5. A simple chip was also designed to pre-load reagents and carry oil-covered PCR reaction droplets. We applied the analyzer to identify eight types of influenza pathogens in human throat swabs, and the results were consistent with the colloidal gold method.
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Técnicas Analíticas Microfluídicas , Ácidos Nucleicos , Robótica , Humanos , Microfluídica/métodos , Ácidos Nucleicos/análise , Técnicas de Amplificação de Ácido Nucleico , Reação em Cadeia da Polimerase em Tempo Real/métodos , Técnicas Analíticas Microfluídicas/métodosRESUMO
Although single-cell multi-omics technologies are undergoing rapid development, simultaneous transcriptome and proteome analysis of a single-cell individual still faces great challenges. Here, we developed a single-cell simultaneous transcriptome and proteome (scSTAP) analysis platform based on microfluidics, high-throughput sequencing, and mass spectrometry technology to achieve deep and joint quantitative analysis of transcriptome and proteome at the single-cell level, providing an important resource for understanding the relationship between transcription and translation in cells. This platform was applied to analyze single mouse oocytes at different meiotic maturation stages, reaching an average quantification depth of 19,948 genes and 2,663 protein groups in single mouse oocytes. In particular, we analyzed the correlation of individual RNA and protein pairs, as well as the meiosis regulatory network with unprecedented depth, and identified 30 transcript-protein pairs as specific oocyte maturational signatures, which could be productive for exploring transcriptional and translational regulatory features during oocyte meiosis.
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Proteoma , Transcriptoma , Animais , Camundongos , Transcriptoma/genética , Proteoma/metabolismo , Oócitos/metabolismo , Oogênese/genética , Perfilação da Expressão Gênica , MeioseRESUMO
Herein, we described an integrated microfluidic system for multi-target biochemical analysis of micro-volumes of blood samples. This system mainly consists of a microfluid handling module, an integrated microwell array chip, a temperature control module and a spectral detection module. A novel microfluidic plasma extraction approach was developed by coupling the filter membrane-based plasma separation technique with the microfluidic liquid-handling technique. With this approach, quantitative extraction of trace blood with volumes as low as a drop (30 µL) can be automatically realized. Multiple operations in multi-target biochemical analysis are achieved including micro-volume blood collecting, quantitative plasma extraction, plasma dilution, plasma distribution, transferring, biochemical reaction and absorption spectroscopy detection. This system was applied to the multi-target biochemical analysis of glucose, cholesterol and total protein in blood samples and could achieve the determination of the target analytes of a 30-µL blood sample within 11 min. The experimental results are consistent with those obtained by a commercial biochemical analyzer.
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Técnicas Analíticas Microfluídicas , Microfluídica , Técnicas Analíticas Microfluídicas/métodos , Análise de Sequência com Séries de Oligonucleotídeos , PlasmaRESUMO
Here we describe an automated and compact pollen detection system that integrates enrichment, in-situ detection and self-cleaning modules. The system can achieve continuous capture and enrichment of pollen grains in air samples by electrostatic adsorption. The captured pollen grains are imaged with a digital camera, and an automated image analysis based on machine vision is performed, which enables a quantification of the number of pollen particles as well as a preliminary classification into two types of pollen grains. In order to optimize and evaluate the system performance, we developed a testing approach that utilizes an airflow containing a precisely metered amount of pollen particles surrounded by a sheath flow to achieve the generation and lossless transmission of standard gas samples. We studied various factors affecting the pollen capture efficiency, including the applied voltage, air flow rate and humidity. Under optimized conditions, the system was successfully used in the measurement of airborne pollen particles within a wide range of concentrations, spanning 3 orders of magnitude.
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Poluentes Atmosféricos , Pólen , Poluentes Atmosféricos/análise , Alérgenos/análise , Processamento de Imagem Assistida por Computador , Pólen/química , Eletricidade EstáticaRESUMO
In this work, a laser-induced fluorescence (LIF) detection system built in a modular assembling mode was developed based on commercial LEGO blocks and 3D printed blocks. We designed and fabricated a variety of 3D printed building blocks fixed with optical components, including laser light source, filters, lens, dichroic mirror, photodiode detector, and control circuits. Utilizing the relatively high positioning precision of the plug-in blocks, a modular construction strategy was adopted using the flexible plug-in combination of the blocks to build a highly sensitive laser-induced fluorescence detection system, LIFGO. The LIFGO system has a simple structure which could be constructed by inexperienced users within 3 h. We optimized the structure and tested the performance of the LIFGO system, and its detection limits for sodium fluorescein solution in 100 µm i.d. and 250 µm i.d. capillaries were 7 nM and 0.9 nM, respectively. Based on the LIFGO system, we also built a simple capillary electrophoresis (CE) system and applied it to the analysis of DNA fragments to demonstrate its application possibility in biochemical analysis. The separation of 7 fragments in DL500 DNA markers were completed in 600 s. Because of the features of low cost (less than $100) and easy-to-build construction, we introduced the LIFGO system to the experimental teaching of instrumental analysis for undergraduate students. The modular construction form of the LIF detection system greatly reduces the threshold of instrument construction, which is conducive to the popularization of the LIF detection technique in routine laboratories as well as the reform of experimental teaching mode.
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Eletroforese Capilar , Lasers , DNA , Fluoresceína , Fluorescência , HumanosRESUMO
In this study, we developed a picoliter-scale partial translational spontaneous injection approach which is suitable for high-speed protein separation under sodium dodecyl sulfate-capillary gel electrophoresis mode. On the basis of this approach, we built a high-speed CE system for protein separation based on a short capillary and slotted-vial array. The system has the advantages of simple structure, ease of building without the requirement of microfabricated devices, convenient operation, and low cost. Under the optimized conditions, picoliter-scale sample plugs (corresponding to â¼65 µm plug length) were obtained, which ensured both the high speed and the high efficiency in protein separation. Five fluorescein isothiocyanate labeled proteins including myoglobin, egg albumin, bovine serum albumin, phosphorylase b, and myosin were separated within 60 s with an effective separation length of 1.5 cm. Theoretical plates per meter ranging from 2.58×105 to 1.28×106 (corresponding to 0.78-3.88 µm plate height) were obtained. The separation speed and separation efficiency of the present system are comparable to those of most microchip-based capillary electrophoresis systems for protein separation. The relative standard deviations of the migration times were in the range of 0.9-1.3% (n=5). Good linear relationships between log relative molecular mass and migration time were obtained in the molecular weigh range of 17,200-500,000, which demonstrate the present system can be applied in protein relative molecular mass determination.
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Eletroforese Capilar/métodos , Proteínas/isolamento & purificação , Dodecilsulfato de Sódio/química , Animais , Bovinos , Eletroforese Capilar/instrumentação , Fluoresceína-5-Isotiocianato , Modelos Lineares , Peso Molecular , Proteínas/química , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
There is a growing urgent requirement for miniaturized laser-induced fluorescence (LIF) detection systems in many research fields. In this work, miniaturized LIF detectors with three different optical configurations of orthogonal, confocal, and oblique were developed, using a laser diode as the excitation source and a photodiode as the photodetector. The computer simulation and experimental methods were used to investigate the distributions of laser scattered light and fluorescent light near the detection window. Other conditions including the solution preparation, sample flow rate, alignment method and filter model were also optimized. Under the optimized conditions, the detection limits of sodium fluorescein for orthogonal and confocal LIF detectors were 40 pM and 50 pM, respectively, while the limit of detection (LOD) for oblique LIF detector were 1 nM (45°) and 7 nM (67.5°). We further built a fully integrated handheld orthogonal LIF detector with a total size of 50 × 20 × 46 mm3, a cost of $380, and a detection limit of 10 pM for sodium fluorescein. It is expected that such a LIF detector could be applied in field analysis as a portable instrument or in other analysis systems as a detection module.
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Drug screening is the process of screening new drugs or leading compounds with biological activity from natural products or synthetic compounds, and it plays an essential role in drug discovery. The discovery of innovative drugs requires the screening of a large number of compounds with appropriate drug targets. With the development of genomics, proteomics, metabolomics, combinatorial chemistry, and other disciplines, the library of drug molecules has been largely expanded, and the number of drug targets is continuously increasing. High-throughput screening systems enable the parallel analysis of thousands of reactions through automated operation, thereby enhancing the experimental scale and efficiency of drug screening. Among them, cell-based high-throughput drug screening has become the main screening mode because it can provide a microenvironment similar to human physiological conditions. However, the current high-throughput screening systems are mainly built based on multiwell plates, which have several disadvantages such as simple cell culture conditions, laborious and time-consuming operation, and high reagent consumption. In addition, it is difficult to achieve complex drug combination screening. Therefore, there is an urgent need for rapid and low-cost drug screening methods to reduce the time and cost of drug development. Microfluidic techniques, which can manipulate and control microfluids in microscale channels, have the advantages of low consumption, high efficiency, high throughput, and automation. It can overcome the shortcomings of screening systems based on multi-well plates and provide an efficient and reliable technical solution for establishing high-throughput cell-based screening systems. Moreover, microfluidic systems can be flexibly changed in terms of cell culture materials, chip structure design, and fluid control methods to enable better control and simulation of cell growth microenvironment. Operations such as cell seeding, culture medium replacement or addition, drug addition and cleaning, and cell staining reagent addition are usually involved in cell-based microfluidic screening systems. These operations are all based on the manipulation of microfluids. This paper reviews the research advances in cell-based microfluidic screening systems using different microfluidic manipulation modes, namely perfusion flow mode, droplet mode, and microarray mode. In addition, the advantages and disadvantages of these systems are summarized. Moreover, the development prospects of high-throughput screening systems based on microfluidic techniques has been looked forward. Furthermore, the current problems in this field and the directions to overcome these problems are discussed.
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Avaliação Pré-Clínica de Medicamentos/métodos , Ensaios de Triagem em Larga Escala , Técnicas Analíticas Microfluídicas , Humanos , MicrofluídicaRESUMO
The identification, sorting and analysis of rare target single cells in human blood has always been a clinically meaningful medical challenge. Here, we developed a microfluidic robot platform for sorting specific rare cells from complex clinical blood samples based on machine vision-based image identification, liquid handling robot and droplet-based microfluidic techniques. The robot integrated a cell capture and droplet generation module, a laser-induced fluorescence imaging module, a target cell identification and data analysis module, and a system control module, which could automatically achieve the scanning imaging of cell array, cell identification, capturing, and droplet generation of rare target cells from blood samples containing large numbers of normal cells. Based on the robot platform, a novel "gold panning" multi-step sorting strategy was proposed to achieve the sorting of rare target cells in large-scale cell samples with high operation efficiency and high sorting purity (>90%). The robot platform and the multi-step sorting strategy were applied in the sorting of circulating endothelial progenitor cells (CEPCs) in human blood to demonstrate their feasibility and application potential in the sorting and analysis of rare specific cells. Approximately 1,000 CEPCs were automatically identified from 3,000,000 blood cells at a scanning speed of ca. 4,000 cells/s, and 20 25-nL droplets containing single CEPCs were generated.
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Técnicas Analíticas Microfluídicas , Robótica , Separação Celular , Humanos , Microfluídica , Imagem ÓpticaRESUMO
This paper reports a fully integrated hand-held photometer based on the liquid-core waveguide (LCW) detection principle for nanoliter-scale samples. All components of the photometer including light-emitting diode (LED) light source, LCW flow cell, photodiode detector, dropper pump, electronic circuit, liquid-crystal display screen, and battery were fully integrated into a small-sized (12 x 4.5 x 2.1 cm) instrument. A bent optical coupler was developed to conduct the detection light into or out of the LCW flow cell through its sidewall. This design allowed the sampling probe, input and output optical couplers, and LCW flow cell to be integrated in a single Teflon AF capillary, which significantly simplified system structure, improved working reliability, and reduced sample consumption. Two UV-LEDs were used as light source in the photometer to achieve dual wavelength detection at 260 and 280 nm, which was applied to assess on-site the quality and quantity of DNA samples. The effective optical path length of the photometer was approximately 15 mm with a sample consumption of only 350 nL. The potential of the photometer applied in point of care testing was also demonstrated in the measurement of total cholesterol in serum samples.
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Microfluidic techniques have the features of high throughput, low consumption, as well as ease of miniaturization, integration, and automation, thus emerging as a feasible solution to cost-effective clinical biochemical analysis. Various clinical biochemical analysis systems based on the microfluidic technique, with different driving and control methods, are introduced in this article, in addition to commercially available microfluidic biochemical analysis instruments. The characteristics of these systems are comprehensively reviewed.