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Liu J, Fu R, Zhang S, Hou J, Ma H, Hu S, Li H, Zhang Y, Wang W, Qiao B, Zang B, Min X, Zhang F, Du J, Yan S. Rapid and multi-target genotyping of Helicobacter pylori with digital microfluidics. Biosens Bioelectron 2024; 256:116282. [PMID: 38626615 DOI: 10.1016/j.bios.2024.116282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 03/18/2024] [Accepted: 04/08/2024] [Indexed: 04/18/2024]
Abstract
Helicobacter pylori (H. pylori) infection correlates closely with gastric diseases such as gastritis, ulcers, and cancer, influencing more than half of the world's population. Establishing a rapid, precise, and automated platform for H. pylori diagnosis is an urgent clinical need and would significantly benefit therapeutic intervention. Recombinase polymerase amplification (RPA)-CRISPR recently emerged as a promising molecular diagnostic assay due to its rapid detection capability, high specificity, and mild reaction conditions. In this work, we adapted the RPA-CRISPR assay on a digital microfluidics (DMF) system for automated H. pylori detection and genotyping. The system can achieve multi-target parallel detection of H. pylori nucleotide conservative genes (ureB) and virulence genes (cagA and vacA) across different samples within 30 min, exhibiting a detection limit of 10 copies/rxn and no false positives. We further conducted tests on 80 clinical saliva samples and compared the results with those derived from real-time quantitative polymerase chain reaction, demonstrating 100% diagnostic sensitivity and specificity for the RPA-CRISPR/DMF method. By automating the assay process on a single chip, the DMF system can significantly reduce the usage of reagents and samples, minimize the cross-contamination effect, and shorten the reaction time, with the additional benefit of losing the chance of experiment failure/inconsistency due to manual operations. The DMF system together with the RPA-CRISPR assay can be used for early detection and genotyping of H. pylori with high sensitivity and specificity, and has the potential to become a universal molecular diagnostic platform.
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Affiliation(s)
- Jinsong Liu
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, 563006, China; College of Laboratory Medicine, Zunyi Medical University, Zunyi, 563000, China
| | - Rongxin Fu
- School of Medical Technology, Beijing Institute of Technology, Beijing, 100081, China; Engineering Research Center of Integrated Acousto-opto-electronic Microsystems, Ministry of Education of China, Beijing, 100081, China
| | - Shuailong Zhang
- School of Integrated Circuits and Electronic, Beijing Institute of Technology, Beijing, 100081, China; Engineering Research Center of Integrated Acousto-opto-electronic Microsystems, Ministry of Education of China, Beijing, 100081, China.
| | - Jialu Hou
- School of Medical Technology, Beijing Institute of Technology, Beijing, 100081, China
| | - Hanbin Ma
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, 215163, China
| | - Siyi Hu
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, 215163, China
| | - Hang Li
- School of Medical Technology, Beijing Institute of Technology, Beijing, 100081, China; Engineering Research Center of Integrated Acousto-opto-electronic Microsystems, Ministry of Education of China, Beijing, 100081, China
| | - Yanli Zhang
- Department of Gastroenterology, China-Japan Friendship Hospital, Beijing, 100029, China
| | - Weian Wang
- Department of Gastroenterology, The Third Medical Center of People's Liberation Army (PLA) General Hospital, Beijing, 100039, China
| | - Bokang Qiao
- Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China; Beijing Institute of Heart, Lung and Vascular Diseases, Key Laboratory of Remodeling-Related Cardiovascular Diseases, Beijing, 100029, China
| | - Baisheng Zang
- Zhejiang Anji GeneDetective Medical Technology Co. Ltd., Anji, 313300, China
| | - Xun Min
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, 563006, China; College of Laboratory Medicine, Zunyi Medical University, Zunyi, 563000, China
| | - Feng Zhang
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, 563006, China; College of Laboratory Medicine, Zunyi Medical University, Zunyi, 563000, China
| | - Jie Du
- Beijing Anzhen Hospital, Capital Medical University, Beijing, 100029, China; Beijing Institute of Heart, Lung and Vascular Diseases, Key Laboratory of Remodeling-Related Cardiovascular Diseases, Beijing, 100029, China.
| | - Shengkai Yan
- Department of Laboratory Medicine, Affiliated Hospital of Zunyi Medical University, Zunyi, 563006, China; College of Laboratory Medicine, Zunyi Medical University, Zunyi, 563000, China.
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Zeng Y, Gan X, Xu Z, Hu X, Hu C, Ma H, Tu H, Chai B, Yang C, Hu S, Chai Y. AIEgens-enhanced rapid sensitive immunofluorescent assay for SARS-CoV-2 with digital microfluidics. Anal Chim Acta 2024; 1298:342398. [PMID: 38462346 DOI: 10.1016/j.aca.2024.342398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 02/14/2024] [Accepted: 02/20/2024] [Indexed: 03/12/2024]
Abstract
BACKGROUND Sensitive and rapid antigen detection is critical for the diagnosis and treatment of infectious diseases, but conventional ELISAs including chemiluminescence-based assays are limited in sensitivity and require many operation steps. Fluorescence immunoassays are fast and convenient but often show limited sensitivity and dynamic range. RESULTS To address the need, an aggregation-induced emission fluorgens (AIEgens) enhanced immunofluorescent assay with beads-based quantification on the digital microfluidic (DMF) platform was developed. Portable DMF devices and chips with small electrodes were fabricated, capable of manipulating droplets within 100 nL and boosting the reaction efficiency. AIEgen nanoparticles (NPs) with high fluorescence and photostability were synthesized to enhance the test sensitivity and detection range. The integration of AIEgen probes, transparent DMF chip design, and the large magnetic beads (10 μm) as capture agents enabled rapid and direct image-taking and signal calculation of the test result. The performance of this platform was demonstrated by point-of-care quantification of SARS-CoV-2 nucleocapsid (N) protein. Within 25 min, a limit of detection of 5.08 pg mL-1 and a limit of quantification of 8.91 pg mL-1 can be achieved using <1 μL sample. The system showed high reproducibility across the wide dynamic range (10-105 pg mL-1), with the coefficient of variance ranging from 2.6% to 9.8%. SIGNIFICANCE This rapid, sensitive AIEgens-enhanced immunofluorescent assay on the DMF platform showed simplified reaction steps and improved performance, providing insight into the small-volume point-of-care testing of different biomarkers in research and clinical applications.
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Affiliation(s)
- Yuping Zeng
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Xiangyu Gan
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Zhourui Xu
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Xiaoxiang Hu
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Chenxuan Hu
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China.
| | - Hanbin Ma
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China; Guangdong ACXEL Micro & Nano Tech Co., Ltd, Foshan, Guangdong province, China.
| | - Hangjia Tu
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Bao Chai
- Department of Dermatology, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, 518052, China; Department of Dermatology, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, 518052, China.
| | - Chengbin Yang
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
| | - Siyi Hu
- CAS Key Laboratory of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou, China.
| | - Yujuan Chai
- Guangdong Key Laboratory of Biomedical Measurements and Ultrasound Imaging, School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518060, China.
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3
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Tong Z, Yang D, Shen C, Li C, Xu X, Li Q, Wu Z, Ma H, Chen F, Mao H. Rapid automated extracellular vesicle isolation and miRNA preparation on a cost-effective digital microfluidic platform. Anal Chim Acta 2024; 1296:342337. [PMID: 38401929 DOI: 10.1016/j.aca.2024.342337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/28/2024] [Accepted: 02/04/2024] [Indexed: 02/26/2024]
Abstract
As a prerequisite for extracellular vesicle (EV) -based studies and diagnosis, effective isolation, enrichment and retrieval of EV biomarkers are crucial to subsequent analyses, such as miRNA-based liquid biopsy for non-small-cell lung cancer (NSCLC). However, most conventional approaches for EV isolation suffer from lengthy procedure, high cost, and intense labor. Herein, we introduce the digital microfluidic (DMF) technology to EV pretreatment protocols and demonstrate a rapid and fully automated sample preparation platform for clinical tumor liquid biopsy. Combining a reusable DMF chip technique with a low-cost EV isolation and miRNA preparation protocol, the platform completes automated sample processing in 20-30 min, supporting immediate RT-qPCR analyses on EV-derived miRNAs (EV-miRNAs). The utility and reliability of the platform was validated via clinical sample processing for EV-miRNA detection. With 23 tumor and 20 non-tumor clinical plasma samples, we concluded that EV-miR-486-5p and miR-21-5p are effective biomarkers for NSCLC with a small sample volumn (20-40 μL). The result was consistent to that of a commercial exosome miRNA extraction kit. These results demonstrate the effectiveness of DMF in EV pretreatment for miRNA detection, providing a facile solution to EV isolation for liquid biopsy.
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Affiliation(s)
- Zhaoduo Tong
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dawei Yang
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Chuanjie Shen
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chao Li
- Department of Neurosurgery, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai, 200092, China
| | - Xin Xu
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Qiushi Li
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Zhenhua Wu
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hui Ma
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Fuxiang Chen
- Department of Clinical Immunology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
| | - Hongju Mao
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.
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4
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Liu X, Cai J, Wang W, Chai Y. Multiplex digital microfluidics using serial controls and its applications in glucose sensing. SLAS Technol 2024; 29:100105. [PMID: 37652174 DOI: 10.1016/j.slast.2023.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 08/02/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
Digital microfluidics (DMF) has found great applications in vitro diagnostics (IVD). Compared to the microfabrication-based DMF, printed circuit board (PCB)-based DMF is more economical and compatible with existing IVD instruments. Despite that, current PCB-based DMF is oftentimes limited by the available droplets that can be controlled simultaneously, compromising their throughput and applications as point-of-care tools. In this work, a platform that simultaneously controls multiple PCB-based DMF plates was constructed. The software and hardware were first developed, followed by the reliability tests. Colorimetric analysis of glucose was applied to the PCB-based DMF, demonstrating the capability of this platform. With the high throughput enabled by simultaneous operations of multiple plates, this PCB-based DMF can potentially allow point-of-care testing with low cost for resource-limited settings.
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Affiliation(s)
- Xinyu Liu
- Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Jinying Cai
- Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Wenjia Wang
- Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China
| | - Yujuan Chai
- Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Department of Biomedical Engineering, Medical School, Shenzhen University, Shenzhen 518060, China.
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5
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Shen C, Zhan C, Tong Z, Yin H, Hui J, Qiu S, Li Q, Xu X, Ma H, Wu Z, Shi N, Mao H. Detecting EGFR gene amplification using a fluorescence in situ hybridization platform based on digital microfluidics. Talanta 2024; 269:125444. [PMID: 38042143 DOI: 10.1016/j.talanta.2023.125444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 11/16/2023] [Accepted: 11/18/2023] [Indexed: 12/04/2023]
Abstract
Signal transduction mediated by epidermal growth factor receptor (EGFR) gene affects the proliferation, invasion, metastasis, and angiogenesis of tumor cells. In particular, non-small cell lung cancer (NSCLC) patients with increased in copy number of EGFR gene are often sensitive to tyrosine kinase inhibitors. Despite being the standard for detecting EGFR amplification in the clinic, fluorescence in situ hybridization (FISH) traditionally involves repetitive and complex benchtop procedures that are not only time consuming but also require well-trained personnel. To address these limitations, we develop a digital microfluidics-based FISH platform (DMF-FISH) that automatically implements FISH operations. This system mainly consists of a DMF chip for reagent operation, a heating array for temperature control and a signal processing system. With the capability of automatic droplet handling and efficient temperature control, DMF-FISH performs cell digestion, gradient elution, hybridization and DAPI staining without manual intervention. In addition to operational feasibility, DMF-FISH yields comparable performance with the benchtop FISH protocol but reducing the consumption of DNA probe by 87 % when tested with cell lines and clinical samples. These results highlight unique advantages of the fully automated DMF-FISH system and thus suggest its great potential for clinical diagnosis and personalized therapy of NSCLC.
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Affiliation(s)
- Chuanjie Shen
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Cheng Zhan
- Department of Thoracic Surgery, Zhongshan Hospital, Fudan University, Shanghai, 200030, China
| | - Zhaoduo Tong
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hao Yin
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianan Hui
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Shihui Qiu
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiushi Li
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Xin Xu
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Hui Ma
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China
| | - Zhenhua Wu
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Nan Shi
- Suzhou Inst Nanotech & Nanob, Chinese Academy of Sciences, Suzhou, 215123, China.
| | - Hongju Mao
- State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China; Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China.
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6
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Sheng H, Chen L, Zhao Y, Long X, Chen Q, Wu C, Li B, Fei Y, Mi L, Ma J. Closed, one-stop intelligent and accurate particle characterization based on micro-Raman spectroscopy and digital microfluidics. Talanta 2024; 266:124895. [PMID: 37454511 DOI: 10.1016/j.talanta.2023.124895] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 06/19/2023] [Accepted: 07/01/2023] [Indexed: 07/18/2023]
Abstract
Monoclonal antibodies are prone to form protein particles through aggregation, fragmentation, and oxidation under varying stress conditions during the manufacturing, shipping, and storage of parenteral drug products. According to pharmacopeia requirements, sub-visible particle levels need to be controlled throughout the shelf life of the product. Therefore, in addition to determining particle counts, it is crucial to accurately characterize particles in drug product to understand the stress condition of exposure and to implement appropriate mitigation actions for a specific formulation. In this study, we developed a new method for intelligent characterization of protein particles using micro-Raman spectroscopy on a digital microfluidic chip (DMF). Several microliters of protein particle solutions induced by stress degradation were loaded onto a DMF chip to generate multiple droplets for Raman spectroscopy testing. By training multiple machine learning classification models on the obtained Raman spectra of protein particles, eight types of protein particles were successfully characterized and predicted with high classification accuracy (93%-100%). The advantages of the novel particle characterization method proposed in this study include a closed system to prevent particle contamination, one-stop testing of morphological and chemical structure information, low sample volume consumption, reusable particle droplets, and simplified data analysis with high classification accuracy. It provides great potential to determine the probable root cause of the particle source or stress conditions by a single testing, so that an accurate particle control strategy can be developed and ultimately extend the product shelf-life.
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Affiliation(s)
- Han Sheng
- Institute of Biomedical Engineering and Technology, Academy for Engineer and Technology, Fudan University, 220 Handan Road, Shanghai, 200433, China
| | - Liwen Chen
- Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Department of Optical Science and Engineering, Fudan University, 220 Handan Road, Shanghai, 200433, China; Ruidge Biotech Co. Ltd., No. 888, Huanhu West 2nd Road, Lin-Gang Special Area, China (Shanghai) Pilot Free Trade Zone, Shanghai, 200131, China
| | - Yinping Zhao
- Institute of Biomedical Engineering and Technology, Academy for Engineer and Technology, Fudan University, 220 Handan Road, Shanghai, 200433, China
| | - Xiangan Long
- Institute of Biomedical Engineering and Technology, Academy for Engineer and Technology, Fudan University, 220 Handan Road, Shanghai, 200433, China
| | - Qiushu Chen
- Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Department of Optical Science and Engineering, Fudan University, 220 Handan Road, Shanghai, 200433, China
| | - Chuanyong Wu
- Shanghai Hengxin BioTechnology, Ltd., 1688 North Guo Quan Rd, Bldg A8, Rm 801, Shanghai, 200438, China
| | - Bei Li
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, No.3888 Dong Nanhu Road, Changchun, Jilin, 130033, China
| | - Yiyan Fei
- Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Department of Optical Science and Engineering, Fudan University, 220 Handan Road, Shanghai, 200433, China
| | - Lan Mi
- Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Department of Optical Science and Engineering, Fudan University, 220 Handan Road, Shanghai, 200433, China.
| | - Jiong Ma
- Institute of Biomedical Engineering and Technology, Academy for Engineer and Technology, Fudan University, 220 Handan Road, Shanghai, 200433, China; Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Department of Optical Science and Engineering, Fudan University, 220 Handan Road, Shanghai, 200433, China; Shanghai Engineering Research Center of Industrial Microorganisms, The Multiscale Research Institute of Complex Systems (MRICS), School of Life Sciences, Fudan University, 220 Handan Road, Shanghai, 200433, China.
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Wan L, Li M, Law MK, Mak PI, Martins RP, Jia Y. Sub-5-Minute Ultrafast PCR using Digital Microfluidics. Biosens Bioelectron 2023; 242:115711. [PMID: 37797533 DOI: 10.1016/j.bios.2023.115711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Revised: 09/08/2023] [Accepted: 09/25/2023] [Indexed: 10/07/2023]
Abstract
The development of a rapid and reliable polymerase chain reaction (PCR) method for point-of-care (POC) diagnosis is crucial for the timely identification of pathogens. Microfluidics, which involves the manipulation of small volumes of fluidic samples, has been shown to be an ideal approach for POC analysis. Among the various microfluidic platforms available, digital microfluidics (DMF) offers high degree of configurability in manipulating μL/nL-scale liquid and achieving automation. However, the successful implementation of ultrafast PCR on DMF platforms presents challenges due to inherent system instability. In this study, we developed a robust and ultrafast PCR in 3.7-5 min with a detection sensitivity comparable to conventional PCR. Specifically, the implementation of the pincer heating scheme homogenises the temperature within a drop. The utilization of a μm-scale porous hydrophobic membrane suppresses the formation of bubbles under high temperatures. The design of a groove around the high-temperature zone effectively mitigates the temperature interference. The integration of a soluble sensor into the droplets provides an accurate and instant in-drop temperature sensing. We envision that the fast, robust, sensitive, and automatic DMF system will empower the POC testing for infectious diseases.
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Affiliation(s)
- Liang Wan
- The State Key Laboratory of Analog and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macao, China
| | - Mingzhong Li
- The State Key Laboratory of Analog and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macao, China; Silergy Semiconductor (Macau) Limited, Macao, China
| | - Man-Kay Law
- The State Key Laboratory of Analog and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macao, China; Faculty of Science and Technology - Electrical and Computer Engineering, University of Macau, Macao, China
| | - Pui-In Mak
- The State Key Laboratory of Analog and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macao, China; Faculty of Science and Technology - Electrical and Computer Engineering, University of Macau, Macao, China
| | - Rui P Martins
- The State Key Laboratory of Analog and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macao, China; Faculty of Science and Technology - Electrical and Computer Engineering, University of Macau, Macao, China; On Leave from Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Yanwei Jia
- The State Key Laboratory of Analog and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macao, China; Faculty of Science and Technology - Electrical and Computer Engineering, University of Macau, Macao, China; MoE Frontiers Science Center for Precision Oncology, University of Macau, Macao, China.
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Nemr CR, Sklavounos AA, Wheeler AR, Kelley SO. Digital microfluidics as an emerging tool for bacterial protocols. SLAS Technol 2023; 28:2-15. [PMID: 36323389 DOI: 10.1016/j.slast.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 09/30/2022] [Accepted: 10/25/2022] [Indexed: 11/05/2022]
Abstract
Bacteria are widely studied in various research areas, including synthetic biology, sequencing and diagnostic testing. Protocols involving bacteria are often multistep, cumbersome and require access to a long list of instruments to perform experiments. In order to streamline these processes, the fluid handling technique digital microfluidics (DMF) has provided a miniaturized platform to perform various steps of bacterial protocols from sample preparation to analysis. DMF devices can be paired/interfaced with instrumentation such as microscopes, plate readers, and incubators, demonstrating their versatility with existing research tools. Alternatively, DMF instruments can be integrated into all-in-one packages with on-chip magnetic separation for sample preparation, heating/cooling modules to perform assay steps and cameras for absorbance and/or fluorescence measurements. This perspective outlines the beneficial features DMF offers to bacterial protocols, highlights limitations of current work and proposes future directions for this tool's expansion in the field.
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Affiliation(s)
- Carine R Nemr
- Department of Chemistry, Harvey Mudd College, 301 Platt Boulevard, Claremont, CA, 91711, USA; Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada.
| | - Alexandros A Sklavounos
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3G9, Canada
| | - Aaron R Wheeler
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3G9, Canada; Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9, Canada
| | - Shana O Kelley
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6, Canada; Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9, Canada; Department of Pharmaceutical Science, University of Toronto, 144 College Street, Toronto, Ontario, M5S 3E5, Canada; Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA; Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
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9
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Li C, Zhai J, Jia Y. Digital Microfluidics with an On-Chip Drug Dispenser for Single or Combinational Drug Screening. Methods Mol Biol 2023; 2679:25-39. [PMID: 37300607 DOI: 10.1007/978-1-0716-3271-0_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Rapid and accurate cancer drug screening is of great importance in precision medicine. However, the limited amount of tumor biopsy samples has hindered the application of traditional drug screening methods with microwell plates for individual patients. A microfluidic system provides an ideal platform for handling trace amounts of samples. This emerging platform has a good role in nucleic acid-related and cell related assays. Nevertheless, convenient drug dispensing remains a challenge for clinical on-chip cancer drug screening. Similar sized droplets are merged to add drugs for a desired screened concentration which significantly complicated the on-chip drug dispensing protocols. Here, we introduce a novel digital microfluidic system with a specially structured electrode (a drug dispenser) to dispense drugs by droplet electro-ejection under a high-voltage actuation signal, which can be conveniently adjusted by external electric controls. With this system, the screened drug concentrations span up to four orders of magnitude with small sample consumption. Various amounts of drugs can be delivered to the cell sample with desired amount in a flexible electric control. Moreover, single drug or combinatorial multidrug on-chip screening can be readily achieved. The drug response of normal MCF-10A breast cells and MDA-MB-231 breast tumor cells to two chemotherapeutic substances, cisplatin (Cis) and epirubicin (EP), was tested individually and in combination for proof-of-principle verification. The comparable on-chip and off-chip results confirmed the feasibility of our innovative DMF system for cancer drug screening.
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Affiliation(s)
- Caiwei Li
- State Key Laboratory of Analog- and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macau, China
- Faculty of Science and Technology - DECE, University of Macau, Macau, China
| | - Jiao Zhai
- State Key Laboratory of Analog- and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macau, China
| | - Yanwei Jia
- State Key Laboratory of Analog- and Mixed-Signal VLSI, Institute of Microelectronics, University of Macau, Macau, China.
- Faculty of Science and Technology - DECE, University of Macau, Macau, China.
- Faculty of Health Sciences, University of Macau, Macau, China.
- MoE Frontiers Science Center for Precision Oncology, University of Macau, Macau, China.
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10
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Li H, Liu X, Zhu F, Ma D, Miao C, Su H, Deng J, Ye H, Dong H, Bai X, Luo Y, Lin B, Liu T, Lu Y. Spatial barcoding-enabled highly multiplexed immunoassay with digital microfluidics. Biosens Bioelectron 2022; 215:114557. [PMID: 35843130 DOI: 10.1016/j.bios.2022.114557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/29/2022] [Accepted: 07/07/2022] [Indexed: 11/18/2022]
Abstract
Digital microfluidics (DMF), facilitating independent manipulation of microliter samples, provides an ideal platform for immunoassay detection; however, suffering limited multiplexity. To address the need, herein we described a digital microfluidics (DMF) platform that realizes spatial barcoding on the Teflon-coated indium tin oxide (ITO) glass side to fulfill highly multiplexed immunoassay (10+) with low-volume samples (∼4 μL) in parallel, representing the highest multiplexing recorded to date for DMF-actuated immunoassay. Planar-based spatial immobilization of multiple capture antibodies was realized on a Teflon-coated ITO glass side, which was then used as the top plate of the DMF device. Droplets containing analytes, secondary antibodies, and fluorescent signaling reporters with low volume, which were electrically manipulated by our DMF control system, were shuttled sequentially along the working electrodes to complete the immuno-reaction. Evaluation of platform performance with recombinant proteins showed excellent sensitivity and reproducibility. To test the feasibility of our platform in analyzing multiplex biomarkers of the immune response, we used lipopolysaccharide-stimulated macrophages as a model system for protein secretion dynamics studies. As a result, temporal profiling of pro-inflammatory cytokine secretion dynamics was obtained. The spatial barcoding strategy presented here is easy-to-operate to enable a more comprehensive evaluation of protein abundance from biological samples, paving the way for new opportunities to realize multiplexity-associated applications with the DMF platform.
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Affiliation(s)
- Huibing Li
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China; College of Stomatology, Dalian Medical University, No. 9, West Section of Lvshun South Road, Lvshunkou District, Dalian, Liaoning, 116044, China
| | - Xianming Liu
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China.
| | - Fengjiao Zhu
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Dachuan Ma
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Chunyue Miao
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Haoran Su
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Jiu Deng
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Haiyue Ye
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Hongyu Dong
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Xue Bai
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Yong Luo
- School of Pharmaceutical Science and Technology, Dalian University of Technology, No.2, Linggong Road, Ganjingzi District, Dalian, Liaoning, 116024, China
| | - Bingcheng Lin
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China
| | - Tingjiao Liu
- Department of Oral Pathology, Shanghai Stomatological Hospital & School of Stomatology, Fudan University, No.2, Tianjin Road, Huangpu District, Shanghai, 200001, China; Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, No.2, Tianjin Road, Huangpu District, Shanghai, 200001, China.
| | - Yao Lu
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No.457, Zhongshan Road, Shahekou District, Dalian, Liaoning, 116023, China.
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11
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Komatsu T, Tokeshi M, Fan SK. Determination of blood lithium-ion concentration using digital microfluidic whole-blood separation and preloaded paper sensors. Biosens Bioelectron 2022; 195:113631. [PMID: 34571482 DOI: 10.1016/j.bios.2021.113631] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 08/26/2021] [Accepted: 09/08/2021] [Indexed: 11/25/2022]
Abstract
Existing microfluidic technologies for blood tests have several limitations, including difficulties in integrating the sample preparation steps, such as blood dilution, and precise metering of tiny samples (microliter) for accurate downstream analyses on a chip. Digital microfluidics (DMF) is a liquid manipulation technique that can provide precise volume control of micro or nano-liter liquid droplets. Without using sensitive but complex detection methods for tiny droplets involving fluorescence, luminescence, and electrochemistry, this article presents a DMF device with embedded paper-based sensors to detect blood lithium-ion (Li+) concentration by colorimetry. Dielectrophoresis on the DMF device between two parallel planar electrodes separates plasma droplets (from tens to hundreds of nanoliters in volume) from undiluted whole blood (a few microliters) within 4 min with an efficiency exceeding 90%. The embedded paper sensors contain a detection reagent to absorb the DMF-transported plasma droplets. These droplets change the color of the paper sensors in accordance with the Li+ concentration. Subsequently, colorimetry is used to reveal the Li+ concentration via image analysis. The proposed method meets the detection-sensitivity requirement for clinical diagnosis of bipolar disorder, making the DMF device a potential therapeutic tool for rapid whole-blood Li+ detection.
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Affiliation(s)
- Takeshi Komatsu
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, 060-8628, Japan
| | - Manabu Tokeshi
- Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita, Sapporo, 060-8628, Japan; Innovative Research Centre for Preventive Medical Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan; Institute of Nano-Life-Systems, Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8601, Japan.
| | - Shih-Kang Fan
- Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS, 66506, USA.
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12
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Piao Y, Yu K, Jones TB, Wang W. Electrical actuation of dielectric droplets by negative liquid dielectrophoresis. Electrophoresis 2021; 42:2490-2497. [PMID: 34310746 DOI: 10.1002/elps.202100093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/19/2021] [Accepted: 07/19/2021] [Indexed: 11/09/2022]
Abstract
This paper presents an electrical actuation scheme of dielectric droplet by negative liquid dielectrophoresis. A general model of lumped parameter electromechanics for evaluating the electromechanical force acting on the droplets is established. The model reveals the influence of actuation voltage, device geometry, and dielectric parameter on the actuation force for both conductive and dielectric medium. Using this model, we compare the actuation forces for four liquid combinations in the parallel-plate geometry and predict the low voltage actuation of dielectric droplets by negative dielectrophoresis. Parallel experimental results demonstrate such electric actuation of dielectric droplets, including droplet transport, splitting, merging, and dispending. All these dielectric droplet manipulations are achieved at voltages < 100 Vrms . The frequency dependence of droplet actuation velocity in aqueous solution is discussed and the existence of surfactant molecules is believed to play an important role by realigning with the AC electric field. Finally, we present coplanar manipulation of oil and water droplets and formation of oil-in-water emulsion droplet by applying the same low voltage.
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Affiliation(s)
- Yuhao Piao
- Department of Instruments Science and Technology, Nanjing University of Science and Technology, Nanjing, P. R. China
| | - Kun Yu
- Department of Instruments Science and Technology, Nanjing University of Science and Technology, Nanjing, P. R. China
| | - Thomas B Jones
- Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
| | - Weiqiang Wang
- Department of Instruments Science and Technology, Nanjing University of Science and Technology, Nanjing, P. R. China
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13
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Chakraborty S, Chakraborty S. An efficient module-less synthesis approach for Digital Microfluidic Biochip. SN Appl Sci 2020; 2:1442. [PMID: 32835163 DOI: 10.1007/s42452-020-3173-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 07/02/2020] [Indexed: 11/26/2022] Open
Abstract
Digital Microfluidic Biochips (DMFBs) will require error-free synthesis techniques which can function at much higher speed while implementing on real-time systems and capable of tackling more complex assay operations. Until now various bio-assays are successfully implemented based on different mixing modules present on such lab-on-chips. In present work, the concept of such dedicated virtual modules has been eliminated and a novel module-less-synthesis (MLS) method is proposed for accomplishing high-performance bio-protocols. Various shift-patterns (movements) of the micro-droplets are identified to accomplish entire mixing in lesser time compared to earlier module-based synthesis methods. We have also computed the percentage of mixing accomplishment for each directional-shift of the mixer-droplet. However, path congestion problem and operational errors are inevitable in MLS approach. Hence, the path congestion and washing problem in MLS is addressed by tweaking the earlier MLS approach and a new modified-MLS (MMLS) method is proposed. Finally, washing optimization technique on MMLS method is also given. Different real-life bio assays like PCR, IVD are tested with the proposed technique as well as synthetic benchmarks (hard test benches) are also incorporated in the experiments. For both kind of benchmarks synthesis performance improved with bioassay completion time ( T max ) significantly reduced compared to existing synthesis approaches on DMFB platform.
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14
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Jain V, Muralidhar K. Electrowetting-on-Dielectric System for COVID-19 Testing. Trans Indian Natl Acad Eng 2020; 5:251-254. [PMID: 38624456 PMCID: PMC7259875 DOI: 10.1007/s41403-020-00113-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/20/2020] [Accepted: 05/23/2020] [Indexed: 11/29/2022]
Abstract
The ongoing viral outbreak labeled COVID-19 is spreading rapidly across states and is posing a great threat to public health. Rapid identification of the virus in the population plays a crucial role in isolating the individual and breaking the transmission chain, apart from initiating an appropriate treatment procedure. Here, we discuss an electrowetting-on-dielectric (EWOD) technology that uses a microprocessor-controlled electrode array to merge a possibly infected sample carried by a liquid drop with a drop of a reagent to carry out the testing process. Changes in color occurring during the mixing process of the drops are imaged using a camera.
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Affiliation(s)
- Vandana Jain
- Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016 India
| | - K. Muralidhar
- Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016 India
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15
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Rismani Yazdi S, Agrawal P, Morales E, Stevens CA, Oropeza L, Davies PL, Escobedo C, Oleschuk RD. Facile actuation of aqueous droplets on a superhydrophobic surface using magnetotactic bacteria for digital microfluidic applications. Anal Chim Acta 2019; 1085:107-116. [PMID: 31522724 DOI: 10.1016/j.aca.2019.08.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/09/2019] [Accepted: 08/01/2019] [Indexed: 12/17/2022]
Abstract
Magnetic actuation provides a low-cost, simple method for droplet manipulation on a digital microfluidic platform. The impetus to move the droplets on a low friction surface can come from internal superparamagnetic particles or paramagnetic salts. Recently, the use of microbes for bio-actuation has been established, where the thrust produced by the microbes can be exploited to exert the force required for droplet movement. This study presents biologically-driven magnetic actuation of droplets on a superhydrophobic surface using magnetotactic bacteria (MTB). MTB-droplets were impelled along various trajectories such as rectangular and figure-of-eight-shaped paths. Droplets were reproducibly actuated with speeds up of to 30 mm s-1. We demonstrated the ability to sequentially merge and mix multiple droplets by merging a 10 μL MTB droplet with two 4 μL colored droplets. The reorientation of MTB in the droplet enhanced mixing rate of the merged fluids by ∼40% compared with the control experiment where no actuation was used. Biologically-driven magnetic actuation was compared with actuation by superparamagnetic particles and paramagnetic salts, in terms of controllability and speed. MTB droplet was moved with the same average speed as other two methods and showed higher response time as the magnet acceleration increased. Lastly, MTB were used to perform a phosphatase assay using endogenous enzyme. The relative absorbance at 405 nm, indicating the production of the yellow product, increased over time and levels off after 75 min.
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Affiliation(s)
- Saeed Rismani Yazdi
- Department of Chemical Engineering, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Prashant Agrawal
- Department of Chemistry, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Erick Morales
- School of Engineering, Department of Electrical Engineering, UNAM, Mexico City, 04510, Mexico
| | - Corey A Stevens
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Laura Oropeza
- School of Engineering, Department of Electrical Engineering, UNAM, Mexico City, 04510, Mexico
| | - Peter L Davies
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Carlos Escobedo
- Department of Chemical Engineering, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
| | - Richard D Oleschuk
- Department of Chemistry, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
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16
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Han S, Liu X, Wang L, Wang Y, Zheng G. An efficient protocol to use feedback-controlling digital microfluidic fluorimetric sensor for detection of mercury (II) in coastal seawaters. MethodsX 2019; 6:1443-1453. [PMID: 31289722 PMCID: PMC6593185 DOI: 10.1016/j.mex.2019.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 06/11/2019] [Indexed: 10/26/2022] Open
Abstract
Mercury ion is a highly toxic anthropogenic pollutants and has serious well-known effects on human. There is an ever-growing demand for convenient detection of mercury driven contaminants in environment, including coastal seawater. However, most of the reported methods are instrument-based and are not easy for portable detection. Our protocol described an efficient Digital Microfluidics method for detecting mercury in coastal seawater samples. It combined the miniaturization/automation potential of digital microfluidics and the sensitivity of fluorescence probe. To overcome a potential risk of driven failure, induced by diversity ion ingredients in seawater, a feedback control loop was included into control system. The method showed satisfied stability and selectivity in Hg sensing under high salinity condition, with the sensitivity of Hg2+ at the parts-per-billion level and total testing time of less than 20 s. With the advantages of being fast, amenable to automation and low cost, this protocol is promising for the formation of simple and rapid sensor device, especially for a routine monitoring and emergency detection of Hg/or other metals in coastal waters.
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Affiliation(s)
- Shuang Han
- Chemical and Environmental Engineering Institute, Dalian University, Dalian, 116622, China.,Environmental Micro Total Analysis Lab, Dalian University, Dalian, 116622, China
| | - Xianming Liu
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116600, China.,Environmental Micro Total Analysis Lab, Dalian University, Dalian, 116622, China
| | - Lin Wang
- Chemical and Environmental Engineering Institute, Dalian University, Dalian, 116622, China.,Environmental Micro Total Analysis Lab, Dalian University, Dalian, 116622, China
| | - Yunhua Wang
- Medical School, Dalian University, Dalian, 116622, China.,Environmental Micro Total Analysis Lab, Dalian University, Dalian, 116622, China
| | - Guoxia Zheng
- Chemical and Environmental Engineering Institute, Dalian University, Dalian, 116622, China.,Environmental Micro Total Analysis Lab, Dalian University, Dalian, 116622, China
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Sathyanarayanan G, Haapala M, Kiiski I, Sikanen T. Digital microfluidic immobilized cytochrome P450 reactors with integrated inkjet-printed microheaters for droplet-based drug metabolism research. Anal Bioanal Chem 2018; 410:6677-6687. [PMID: 30073515 PMCID: PMC6132693 DOI: 10.1007/s00216-018-1280-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 06/27/2018] [Accepted: 07/17/2018] [Indexed: 01/23/2023]
Abstract
We report the development and characterization of digital microfluidic (DMF) immobilized enzyme reactors (IMERs) for studying cytochrome P450 (CYP)-mediated drug metabolism on droplet scale. The on-chip IMERs consist of porous polymer (thiol-ene) monolith plugs prepared in situ by photopolymerization and functionalized with recombinant CYP1A1 isoforms (an important detoxification route for many drugs and other xenobiotics). The DMF devices also incorporate inexpensive, inkjet-printed microheaters for on-demand regio-specific heating of the IMERs to physiological temperature, which is crucial for maintaining the activity of the temperature-sensitive CYP reaction. For on-chip monitoring of the CYP activity, the DMF devices were combined with a commercial well-plate reader, and a custom fluorescence quantification method was developed for detection of the chosen CYP1A1 model activity (ethoxyresorufin-O-deethylation). The reproducibility of the developed assay was examined with the help of ten parallel CYP-IMERs. All CYP-IMERs provided statistically significant difference (in fluorescence response) compared to any of the negative controls (including room-temperature reactions). The average (n = 10) turnover rate was 20.3 ± 9.0 fmol resorufin per minute. Via parallelization, the concept of the droplet-based CYP-IMER developed in this study provides a viable approach to rapid and low-cost prediction of the metabolic clearance of new chemical entities in vitro.
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Affiliation(s)
- Gowtham Sathyanarayanan
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
| | - Markus Haapala
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
| | - Iiro Kiiski
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland
| | - Tiina Sikanen
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, 00014, Helsinki, Finland.
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18
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Millington D, Norton S, Singh R, Sista R, Srinivasan V, Pamula V. Digital microfluidics comes of age: high-throughput screening to bedside diagnostic testing for genetic disorders in newborns. Expert Rev Mol Diagn 2018; 18:701-712. [PMID: 30004274 DOI: 10.1080/14737159.2018.1495076] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Digital microfluidics (DMF) is an emerging technology with the appropriate metrics for application to newborn and high-risk screening for inherited metabolic disease and other conditions that benefit from early treatment. Areas covered: This review traces the development of electrowetting-based DMF technology toward the fulfillment of its promise to provide an inexpensive platform to conduct enzymatic assays and targeted biomarker assays at the bedside. The high-throughput DMF platform, referred to as SEEKER®, was recently authorized by the United States Food and Drug Administration to screen newborns for four lysosomal storage disorders (LSDs) and is deployed in newborn screening programs in the United States. The development of reagents and methods for LSD screening and results from screening centers are reviewed. Preliminary results from a more compact DMF device, to perform disease-specific test panels from small volumes of blood, are also reviewed. Literature for this review was sourced using principal author and subject searches in PubMed. Expert commentary: Newborn screening is a vital and highly successful public health program. DMF technology adds value to the current testing platforms that will benefit apparently healthy newborns with underlying genetic disorders and infants at-risk for conditions that present with symptoms in the newborn period.
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Affiliation(s)
- David Millington
- a Department of Pediatrics , Duke University Medical Center , Durham , NC , USA
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19
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Khilko Y, Weyman PD, Glass JI, Adams MD, McNeil MA, Griffin PB. DNA assembly with error correction on a droplet digital microfluidics platform. BMC Biotechnol 2018; 18:37. [PMID: 29859085 PMCID: PMC5984785 DOI: 10.1186/s12896-018-0439-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 04/24/2018] [Indexed: 12/02/2022] Open
Abstract
Background Custom synthesized DNA is in high demand for synthetic biology applications. However, current technologies to produce these sequences using assembly from DNA oligonucleotides are costly and labor-intensive. The automation and reduced sample volumes afforded by microfluidic technologies could significantly decrease materials and labor costs associated with DNA synthesis. The purpose of this study was to develop a gene assembly protocol utilizing a digital microfluidic device. Toward this goal, we adapted bench-scale oligonucleotide assembly methods followed by enzymatic error correction to the Mondrian™ digital microfluidic platform. Results We optimized Gibson assembly, polymerase chain reaction (PCR), and enzymatic error correction reactions in a single protocol to assemble 12 oligonucleotides into a 339-bp double- stranded DNA sequence encoding part of the human influenza virus hemagglutinin (HA) gene. The reactions were scaled down to 0.6-1.2 μL. Initial microfluidic assembly methods were successful and had an error frequency of approximately 4 errors/kb with errors originating from the original oligonucleotide synthesis. Relative to conventional benchtop procedures, PCR optimization required additional amounts of MgCl2, Phusion polymerase, and PEG 8000 to achieve amplification of the assembly and error correction products. After one round of error correction, error frequency was reduced to an average of 1.8 errors kb− 1. Conclusion We demonstrated that DNA assembly from oligonucleotides and error correction could be completely automated on a digital microfluidic (DMF) platform. The results demonstrate that enzymatic reactions in droplets show a strong dependence on surface interactions, and successful on-chip implementation required supplementation with surfactants, molecular crowding agents, and an excess of enzyme. Enzymatic error correction of assembled fragments improved sequence fidelity by 2-fold, which was a significant improvement but somewhat lower than expected compared to bench-top assays, suggesting an additional capacity for optimization. Electronic supplementary material The online version of this article (10.1186/s12896-018-0439-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yuliya Khilko
- Stanford Genome Technology Center, Stanford University, 3165 Porter Drive, Palo Alto, CA, 94304, USA.,Department of Biomedical, Chemical and Materials Engineering, San Jose State University, 1 Washington Sq, San Jose, CA, 95192, USA
| | - Philip D Weyman
- J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA, 92037, USA
| | - John I Glass
- J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA, 92037, USA
| | - Mark D Adams
- J. Craig Venter Institute, 4120 Capricorn Lane, La Jolla, CA, 92037, USA
| | - Melanie A McNeil
- Department of Biomedical, Chemical and Materials Engineering, San Jose State University, 1 Washington Sq, San Jose, CA, 95192, USA
| | - Peter B Griffin
- Stanford Genome Technology Center, Stanford University, 3165 Porter Drive, Palo Alto, CA, 94304, USA.
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20
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Abstract
Liquid marble as a bioreactor platform for cell-based studies has received significant attention, especially for developing 3D cell-based assays. This platform is particularly suitable for 3D in-vitro modeling of cell-cell interactions. For the first time, we demonstrated the interaction of olfactory ensheathing cells (OECs) with nerve debris and meningeal fibroblast using liquid marbles. As the transplantation of OECs can be used for repairing nerve injury, degenerating cell debris within the transplantation site can adversely affect the survival of transplanted OECs. In this paper, we used liquid marbles to mimic the hostile 3D environment to analyze the functional behavior of the cells and to form the basis for cell-based therapy. We show that OECs interact with debris and enhanced cellular aggregation to form a larger 3D spheroidal tissue. However, these spheroids indicated limitation in biological functions such as the inability of cells within the spheroids to migrate out and adherence to neighboring tissue by fusion. The coalescence of two liquid marbles allows for analyzing the interaction between two distinct cell types and their respective environment. We created a microenvironment consisting of 3D fibroblast spheroids and nerve debris and let it interact with OECs. We found that OECs initiate adherence with nerve debris in this 3D environment. The results suggest that liquid marbles are ideal for developing bioassays that could substantially contribute to therapeutic applications. Especially, insights for improving the survival and adherence of transplanted cells.
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Affiliation(s)
- Raja K Vadivelu
- School of Natural Sciences, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia.
| | - Harshad Kamble
- QLD Micro- and Nanotechnology Centre, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia
| | - Ahmed Munaz
- QLD Micro- and Nanotechnology Centre, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia
| | - Nam-Trung Nguyen
- QLD Micro- and Nanotechnology Centre, Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, QLD 4111, Australia.
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21
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Choi K, Boyacı E, Kim J, Seale B, Barrera-Arbelaez L, Pawliszyn J, Wheeler AR. A digital microfluidic interface between solid-phase microextraction and liquid chromatography-mass spectrometry. J Chromatogr A 2016; 1444:1-7. [PMID: 27048987 DOI: 10.1016/j.chroma.2016.03.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 11/28/2022]
Abstract
We introduce a method to couple solid-phase microextraction (SPME) with HPLC-MS using digital microfluidics (DMF). In the new system, SPME fibers are used to extract analytes from complex sample solutions, after which the analytes are desorbed into solvent droplets in a DMF device. The open geometry of DMF allows straightforward insertion of SPME fibers without requiring a complicated interface, and automated droplet manipulation enables multiplexed processing of the fibers. In contrast to other multiplexed SPME elution interfaces, the low volumes inherent to DMF allow for pre-concentration of analytes prior to analysis. The new SPME-DMF-HPLC-MS method was applied to the quantification of pg/mL-level free steroid hormones in urine. We propose that this new method will be useful for a wide range of applications requiring cleanup and pre-concentration with convenient coupling to high-performance analytical techniques.
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Affiliation(s)
- Kihwan Choi
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON M5S 3E1, Canada; Division of Metrology for Quality of Life, Korea Research Institute of Standards and Science, Yuseong-gu, Daejeon 34113, Republic of Korea
| | - Ezel Boyacı
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Jihye Kim
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada
| | - Brendon Seale
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada
| | - Luis Barrera-Arbelaez
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada
| | - Janusz Pawliszyn
- Department of Chemistry, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Aaron R Wheeler
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON M5S 3H6, Canada; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON M5S 3E1, Canada; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON M5S 3G9, Canada.
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22
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Shamsi MH, Choi K, Ng AHC, Chamberlain MD, Wheeler AR. Electrochemiluminescence on digital microfluidics for microRNA analysis. Biosens Bioelectron 2015; 77:845-52. [PMID: 26516684 DOI: 10.1016/j.bios.2015.10.036] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/08/2015] [Accepted: 10/12/2015] [Indexed: 01/04/2023]
Abstract
Electrochemiluminescence (ECL) is a sensitive analytical technique with great promise for biological applications, especially when combined with microfluidics. Here, we report the first integration of ECL with digital microfluidics (DMF). ECL detectors were fabricated into the ITO-coated top plates of DMF devices, allowing for the generation of light from electrically excited luminophores in sample droplets. The new system was characterized by making electrochemical and ECL measurements of soluble mixtures of tris(phenanthroline)ruthenium(II) and tripropylamine (TPA) solutions. The system was then validated by application to an oligonucleotide hybridization assay, using magnetic particles bearing 21-mer, deoxyribose analogues of the complement to microRNA-143 (miRNA-143). The system detects single nucleotide mismatches with high specificity, and has a limit of detection of 1.5 femtomoles. The system is capable of detecting miRNA-143 in cancer cell lysates, allowing for the discrimination between the MCF-7 (less aggressive) and MDA-MB-231 (more aggressive) cell lines. We propose that DMF-ECL represents a valuable new tool in the microfluidics toolbox for a wide variety of applications.
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Affiliation(s)
- Mohtashim H Shamsi
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1
| | - Kihwan Choi
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1
| | - Alphonsus H C Ng
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON, Canada M5S 3G9
| | - M Dean Chamberlain
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1
| | - Aaron R Wheeler
- Department of Chemistry, University of Toronto, 80 St George St., Toronto, ON, Canada M5S 3H6; Donnelly Centre for Cellular and Biomolecular Research, 160 College St., Toronto, ON, Canada M5S 3E1; Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College St., Toronto, ON, Canada M5S 3G9.
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23
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Graham C, Sista RS, Kleinert J, Wu N, Eckhardt A, Bali D, Millington DS, Pamula VK. Novel application of digital microfluidics for the detection of biotinidase deficiency in newborns. Clin Biochem 2013; 46:1889-91. [PMID: 24036022 DOI: 10.1016/j.clinbiochem.2013.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 08/16/2013] [Accepted: 09/04/2013] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Newborn screening for biotinidase deficiency can be performed using a fluorometric enzyme assay on dried blood spot specimens. As a pre-requisite to the consolidation of different enzymatic assays onto a single platform, we describe here a novel analytical method for detecting biotinidase deficiency using the same digital microfluidic cartridge that has already been demonstrated to screen for five lysosomal storage diseases (Pompe, Fabry, Gaucher, Hurler and Hunter) in a multiplex format. METHODS A novel assay to quantify biotinidase concentration in dried blood spots (DBS) was developed and optimized on the digital microfluidic platform using proficiency testing samples from the Centers for Disease Control and Prevention. The enzymatic assay uses 4-methylumbelliferyl biotin as the fluorogenic substrate. Biotinidase deficiency assays were performed on normal (n=200) and deficient (n=7) newborn DBS specimens. RESULTS Enzymatic activity analysis of biotinidase deficiency revealed distinct separation between normal and affected DBS specimens using digital microfluidics and these results matched the expected activity. CONCLUSIONS This study has demonstrated performance of biotinidase deficiency assays by measurement of 4-methylumbelliferyl product on a digital microfluidic platform. Due to the inherent ease in multiplexing on such a platform, consolidation of other fluorometric assays onto a single cartridge may be realized.
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Affiliation(s)
- Carrie Graham
- Advanced Liquid Logic, Inc. (an Illumina Company), PO Box 14025, Research Triangle Park, NC 27709, USA
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24
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Sista RS, Wang T, Wu N, Graham C, Eckhardt A, Winger T, Srinivasan V, Bali D, Millington DS, Pamula VK. Multiplex newborn screening for Pompe, Fabry, Hunter, Gaucher, and Hurler diseases using a digital microfluidic platform. Clin Chim Acta 2013; 424:12-8. [PMID: 23660237 DOI: 10.1016/j.cca.2013.05.001] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/29/2013] [Accepted: 05/01/2013] [Indexed: 12/15/2022]
Abstract
PURPOSE New therapies for lysosomal storage diseases (LSDs) have generated interest in screening newborns for these conditions. We present performance validation data on a digital microfluidic platform that performs multiplex enzymatic assays for Pompe, Fabry, Hunter, Gaucher, and Hurler diseases. METHODS We developed an investigational disposable digital microfluidic cartridge that uses a single dried blood spot (DBS) punch for performing a 5-plex fluorometric enzymatic assay on up to 44 DBS samples. Precision and linearity of the assays were determined by analyzing quality control DBS samples; clinical performance was determined by analyzing 600 presumed normal and known affected samples (12 for Pompe, 7 for Fabry and 10 each for Hunter, Gaucher and Hurler). RESULTS Overall coefficient of variation (CV) values between cartridges, days, instruments, and operators ranged from 2 to 21%; linearity correlation coefficients were ≥0.98 for all assays. The multiplex enzymatic assay performed from a single DBS punch was able to discriminate presumed normal from known affected samples for 5 LSDs. CONCLUSIONS Digital microfluidic technology shows potential for rapid, high-throughput screening for 5 LSDs in a newborn screening laboratory environment. Sample preparation to enzymatic activity on each cartridge is less than 3h.
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Affiliation(s)
- Ramakrishna S Sista
- Advanced Liquid Logic, Inc., P.O. Box 14025, Research Triangle Park, NC 27709, USA
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25
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Abstract
Picoliter droplets actuated on an electrowetting-on-dielectric (EWD) actuator are demonstrated. In this study, the physical scaling of electrodes for 33 μm and 21 μm EWD devices resulted in droplets of 12 pl and 5 pl being dispensed respectively in conjunction with 3 μm SU8 gaskets. The stacked multi-layer insulators in the actuators consisted of 200 nm tantalum pentoxide (Ta2O5) and 200 nm parylene C films deposited and coated with 70 nm of CYTOP. The voltages for dispensing droplets on chips without any external pressure sources are 17.1 Vrms and 22 Vrms for these two sets of devices. A 12 pl droplet can be split into two 6 pl daughter droplets at 18.7 Vrms with 33 μm electrode devices. Droplet manipulation is also demonstrated with paramagnetic beads and buffer solutions with proteins. In addition, electrodes with interlocking protrusions and special featured reservoir gasket are designed to facilitate droplet dispensing on these scaled EWD devices. In order to improve sealing of the two-piece sandwich EWD structure, a soft material, Norland Optical Adhesive (NOA), was coated on the top plate along with pressure on top. We demonstrate that based on fundamental theories and experiments, the dimensional scaling of EWD devices has not yet met a limitation as long as the EWD device can be sealed well.
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