Multifunctional Microfluidic Chip Research Articles

A colorimetric/electrochemical microfluidic biosensor using target-triggered DNA hydrogels for organophosphorus detection

Organophosphorus compounds are widely distributed and highly toxic to the environment and living organisms. The current detection of organophosphorus compounds is based on a single-mode method, which makes it challenging to achieve good portability, accuracy, and sensitivity simultaneously. This study designed a multifunctional microfluidic chip to develop a dual-mode biosensor employing a DNA hydrogel as a carrier and aptamers as recognition probes for the colorimetric/electrochemical detection of malathion, an organophosphorus compound. The biosensor balanced portability and stability by combining a microfluidic chip and target-triggered DNA hydrogel-sensing technologies. Moreover, the biosensor based on target-triggered DNA hydrogel modified microfluidic developed in this study exhibited a dual-mode response to malathion, providing both colorimetric and electrochemical signals. The colorimetric mode enables rapid visualization and qualitative detection and, when combined with a smartphone, allows on-site quantitative analysis with a detection limit of 56 nM. The electrochemical mode offers a broad linear range (0.01–3000 μM) and high sensitivity (a limit of detection of 5 nM). The two modes could validate each other and improve the accuracy of detection. The colorimetric/electrochemical dual-mode biosensor based on target-triggered DNA hydrogel modified microfluidic chip offers a portable, simple, accurate, and sensitive strategy for detecting harmful environmental and food substances.

A Microfluidic Chip-Based Automated System for Whole-Course Monitoring the Drug Responses of Organoids.

Tumor patients-derived organoids, as a promising preclinical prediction model, have been utilized to evaluate ex vivo drug responses for formulating optimal therapeutic strategies. Detecting adenosine triphosphate (ATP) has been widely used in existing organoid-based drug response tests. However, all commercial ATP detection kits containing the cell lysis procedure can only be applied for single time point ATP detection, resulting in the neglect of dynamic ATP variations in living cells. Meanwhile, due to the limited number of viable organoids from a single patient, it is impractical to exhaustively test all potential time points in search of optimal ones. In this work, a multifunctional microfluidic chip was developed to perform all procedures of organoid-based drug response tests, including establishment, culturing, drug treatment, and ATP monitoring of organoids. An ATP sensor was developed to facilitate the first successful attempt on whole-course monitoring the growth status of fragile organoids. To realize a clinically applicable automatic system for the drug testing of lung cancer, a microfluidic chip based automated system was developed to perform entire organoid-based drug response test, bridging the gap between laboratorial manipulation and clinical practices, as it outperformed previous methods by improving data repeatability, eliminating human error/sample loss, and more importantly, providing a more accurate and comprehensive evaluation of drug effects.

Enrichment and detection of VEGF165 in blood samples on a microfluidic chip integrated with multifunctional units.

In this paper, a multifunctional microfluidic chip integrated with a centrifugal separation zone, aqueous two-phase system (ATPS) mixing zone and enrichment detection zone was proposed and fabricated. An automatic and efficient separation and quantitative analysis method for vascular endothelial growth factor 165 (VEGF165) in whole blood samples was established with the designed microfluidic chip. A blood sample was divided into blood cells and plasma in the centrifugation zone. In the ATPS mixing zone, plasma was mixed with PEG/KH2PO4 aqueous two-phase solution containing Apt-Au NP nanoprobes. In the enrichment detection zone, the mixture was separated on CN140 modified with a ZnO NP-anti VEGF165 nanostructure. The VEGF165 captured by Apt-Au NPs was distributed in the PEG phase, concentrated at the front of CN140 and combined with anti-VEGF165 to form a sandwich structure. The sensitive detection of VEGF165 was achieved through fluorescence resonance energy transfer between rhodamine B and Au NPs on the nanoprobe. Under the optimized rotation program, capillary and centrifugal forces propelled the fluid in the whole process of pretreatment and detection. The detection linear range was between 1 pg mL-1 and 50 ng mL-1, the detection limit of VEGF165 in blood was 0.22 pg mL-1 and the enrichment efficiency was 983. It was illustrated that a convenient and reliable way for detection of tumor markers based on the multifunctional microfluidic chip was provided and it has a potential value for early screening and prognosis of clinical cancer.

EGFR mutation detection of lung circulating tumor cells using a multifunctional microfluidic chip

Microfluidics has become a reliable platform for circulating tumor cells (CTCs) detection because of its high integration, small size, low consumption of reagents and rapid response. Here, we developed a multifunctional microfluidic device consists of three parts, including CTCs capture area, single-layer membrane valves area, and microcavity nucleic acid detection and analysis region based on digital polymerase chain reaction (dPCR), allowing CTCs capture, lysis, and genetic characterization to be performed on a single chip. The CTCs capture chip is coupled to the nucleic acid detection chip via a control valve. CTCs were firstly trapped in the CTC capture area, and then lysed using proteinase K to release nucleic acids. Subsequently CTCs lysate was transferred into nucleic acid detection area consisting of 12800 micro-cavity chambers for nucleic acids detection. To evaluate the performance of this chip, this study detected EGFR-L858R mutation in lung cancer cell lines H1975 and A549 cells, as well as leukocytes from normal donors. The results showed that positive signals were only observed in H1975 cells, and the detected value had a high linear relationship with the expected value (R2 = 0.9897). In conclusion, this multi-functional microfluidic chip that integrates CTCs capture, lysis and nucleic acid detection can successfully detect gene mutations in CTCs, providing reference for tumor-targeted drugs and precise diagnosis and treatment.

Multifunctional microfluidic chip for cancer diagnosis and treatment.

Microfluidic chip is not a chip in the traditional sense. It is technologies that control fluids at the micro level. As a burgeoning biochip, microfluidic chips integrate multiple disciplines, including physiology, pathology, cell biology, biophysics, engineering mechanics, mechanical design, materials science, and so on. The application of microfluidic chip has shown tremendous promise in the field of cancer therapy in the past three decades. Various types of cell and tissue cultures, including 2D cell culture, 3D cell culture and tissue organoid culture could be performed on microfluidic chips. Patient-derived cancer cells and tissues can be cultured on microfluidic chips in a visible, controllable, and high-throughput manner, which greatly advances the process of personalized medicine. Moreover, the functionality of microfluidic chip is greatly expanding due to the customizable nature. In this review, we introduce its application in developing cancer preclinical models, detecting cancer biomarkers, screening anti-cancer drugs, exploring tumor heterogeneity and producing nano-drugs. We highlight the functions and recent development of microfluidic chip to provide references for advancing cancer diagnosis and treatment.

Impedimetric detection of bacteria by using a microfluidic chip and silver nanoparticle based signal enhancement.

The authors describe a method that can significantly improve the performance of impedimetric detection of bacteria. A multifunctional microfluidic chip was designed consisting of interdigitated microelectrodes and a micro-mixing zone with a Tesla structure. This maximizes the coating of bacterial surfaces with nanoparticles and results in improved impedimetric detection. The method was applied to the detection of Escherichia coli O157:H7 (E. coli). Silver enhancement was accomplished by coating E.coli with the cationic polymer diallyldimethylammonium chloride (PDDA) to form positively charged E. coli/PDDA complexes. Then, gold nanoparticles (AuNPs) were added, and the resulting E. coli/PDDA/AuNPs complexes were collected at interdigitated electrodes via positive dielectrophoresis (pDEP). A silver adduct was then formed on the E. coli/PDDA/AuNP complexes by using silver enhancement solutions and by using the AuNPs as catalysts. The combination of pDEP based capture and of using silver adducts reduces impedance by increasing the conductivity of the solution and the double layer capacitance around the microelectrodes. Impedance decreases linearly in the 2 × 103-2 × 105cfu·mL-1 E. coli concentration range, with a 500cfu·mL-1 detection limit. Egg shell wash samples and tap water spiked with E. coli were successfully used for validation, and this demonstrates the practical application of this method. Graphical abstract Schematic representation of the AuNP@Ag enhancement method integrated with multifunctional microfluidic chip platform for impedimetric quantitation of bacteria. The method significantly improves the performance of impedimetric detection of bacteria.

Multifunctional microfluidic chip for optical nanoprobe based RNA detection \u2013 application to Chronic Myeloid Leukemia

Many diseases have their treatment options narrowed and end up being fatal if detected during later stages. As a consequence, point-of-care devices have an increasing importance for routine screening applications in the health sector due to their portability, fast analyses and decreased cost. For that purpose, a multifunctional chip was developed and tested using gold nanoprobes to perform RNA optical detection inside a microfluidic chip without the need of molecular amplification steps. As a proof-of-concept, this device was used for the rapid detection of chronic myeloid leukemia, a hemato-oncological disease that would benefit from early stage diagnostics and screening tests. The chip passively mixed target RNA from samples, gold nanoprobes and saline solution to infer a result from their final colorimetric properties. An optical fiber network was used to evaluate its transmitted spectra inside the chip. Trials provided accurate output results within 3 min, yielding signal-to-noise ratios up to 9 dB. When compared to actual state-of-art screening techniques of chronic myeloid leukemia, these results were, at microscale, at least 10 times faster than the reported detection methods for chronic myeloid leukemia. Concerning point-of-care applications, this work paves the way for other new and more complex versions of optical based genosensors.

Research progress on the radio-synthesis of PET probes in microfluidic chips

Radio-synthesis of PET tracers in microfluidic chip system for imaging research could facilitate synthesis and screening of radiotracer. Moreover, modular and multi-functional microfluidic chip synthesis system could realize the combination of functional modules, synthetic automation, system integration and improvement of radiochemical protection. In this review, research progress in microfluidic chip system for radio-synthesis of PET tracers has been summarized. Key words: Molecular probes; Positron-emission tomography; Lab-on-a-chip devices; Trends

Detection of HepG2 Cells in Artificial Samples by Multifunctional Microfluidic Chip

Abstract A multifunctional microfluidic chip integrated with multi-orifice flow fractionation (MOFF) and magnetic capture technique was developed to specifically separate and capture HepG2 cells in artificial samples. The chip contained a glass substrate and a polydimethylsiloxane (PDMS) micro-channel cover plate. The PDMS cover plate consisted of three 10-mm-long injection channels, a MOFF separation zone and a hexagonal cavity cell enrichment detection zone. The MOFF separation zone, with a total length of 20 mm, was consisted of 80 semi-rhombic shrinkage and expansion units with a length of 0.18 mm, a depth of 50 μm, a shrinkage area width of 0.06 mm, and an expansion area of 0.20 mm. The angle between each group of shrinkage and expansion units was 103.0°. In this work, HepG2-blood cell suspension was used as the sample. Based on the principle that the magnetic beads surface modified c-Met antibody could specifically bind to HepG2 cells, an immune-magnetic beads (anti-MNCs) suspension at a concentration of 50 μg mL−1 was prepared by surface carboxylated beads, EDC (1 mg mL−1), NHS (1 mg mL−1) and c-Met antibody. At the optimized flow rate of 50 μL min−1, HepG2 in suspension samples was efficiently captured at the detection zone of chip via a magnetic field. The carbon quantum dots were prepared by microwave heating with citric acid and thiourea to label HepG2 cells which made it possible that the captured HepG2 could be visualized in-situ. The captured cells in the chip detection area were counted by microscope. It was shown that the capture rate of HepG2 cells was 88.5% ± 6.7% (500 μL volume contained 106 blood cells and 10 HepG2 cells). The results demonstrated the developed multifunctional microfluidic chip may serve as a promising tool for separation and capture of tumour cells.

Microvalve controlled multi-functional microfluidic chip for divisional cell co-culture

Pneumatic micro-valve controlled microfluidic chip provides precise fluidic control for cell manipulation. In this paper, a multi-functional microfluidic chip was designed for three separate experiments: 1. Different cell lines were dispensed and cultured; 2. Three transfected SH-SY5Y cells were introduced and treated with methyl-phenyl-pyridinium (MPP+) as drug delivery mode; 3. Specific protection and interaction were observed among cell co-culture after nerve damage. The outcomes revealed the potential and practicability of our entire multi-functional pneumatic chip system on different cell biology applications.

Precisely Enumerating Circulating Tumor Cells Utilizing a Multi-Functional Microfluidic Chip and Unique Image Interpretation Algorithm.

Enumerating circulating tumor cells (CTCs) has been demonstrably useful in cancer treatment. Although there are several approaches that have proved effective in isolating CTC-like cells, the crucial identification of CTCs continues to rely on the manual interpretation of immunofluorescence images of all cells that have been isolated. This procedure is time consuming and more importantly, CTC identification relies on subjective criteria that may differ between examiners. In this study, we describe the design, testing, and verification of a microfluidic platform that provides accurate and automated CTC enumeration using a common objective criterion.Methods: The platform consists of a multi-functional microfluidic chip and a unique image processing algorithm. The microfluidic chip integrates blood filtering, cell isolation, and single cell positioning to ensure minimal cell loss, efficient cell isolation, and fixed arraying of single cells to facilitate downstream image processing. By taking advantage of the microfluidic chip design to reduce calculation loads and eliminate measurement errors, our specially designed algorithm has the capability of rapidly interpreting hundreds of images to provide accurate CTC counts.Results: Following intensive optimization of the microfluidic chip, the image processing algorithm, and their collaboration, we verified the complete platform by enumerating CTCs from six clinical blood samples of patients with breast cancer. Compared to tube-based CTC isolation and manual CTC identification, our platform had better accuracy and reduced the time needed from sample loading to result review by 50%.Conclusion: This automated CTC enumeration platform demonstrates not only a sound strategy in integrating a specially designed multi-functional microfluidic chip with a unique image processing algorithm for robust, accurate, and “hands-free” CTC enumeration, but may also lead to its use as a novel in vitro diagnostic device used in clinics and laboratories as readily as a routine blood test.

Ca2+ Mediates the Adhesion of Breast Cancer Cells in Self-Assembled Multifunctional Microfluidic Chip Prepared with Carbohydrate Beads

Calcium has been demonstrated to have a fundamental role in cell-cell recognition mediating the carbohydrate- carbohydrate and the protein-carbohydrate interactions. A self assembled multifunctional microfluidic array has been used to exploit the interactions between breast tumor cells and an engineered surface. Engineering concerns the topology of the surface, since microbeads have been used to increase the micro roughness of the surface, the biochemistry, since the microbeads are conjugated by carbohydrates before being integrated inside the microfluidic chamber. Microfluidic environment permits to control parameters such as the shear force and the velocity and mimicking the microenvironment surrounding the cells. To this end it is extremely important to investigate the role of calcium in cell carbohydrate interactions in a microfluidic environment. Investigation has been performed varying the calcium concentration of cell media and the fluidic condition. Breast tumor cells have been used. Static and dynamic experiments have been performed. Static experiments have shown that differences in the cell adhesion behavior are only detectable when dealing with calcium free buffer, whilst the results of adhesion in correspondence of different carbohydrates have been lost when dealing with calcium enriched media. Adhesion of glucose is independent on the composition of the buffer. At 3000 μl sec-1 60 and 80% of adherent cells have been counted in according to the free and enriched calcium media. The trend of the results from the dynamic experiments is not affected by the presence of calcium, and three different conditions can be identified. In particular, between 10 and 15 μl min-1 they adhere and start roll on the substrate at high flow rate. We assume that during the first seconds calcium is not able to drive the interaction between carbohydrates and cells and hydrodynamic phenomena, the balance between shear force and velocity, play the most important role.