1
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Shin S, Kim YJ, Yun HG, Chung H, Cho H, Choi S. 3D Amplified Single-Cell RNA and Protein Imaging Identifies Oncogenic Transcript Subtypes in B-Cell Acute Lymphoblastic Leukemia. ACS NANO 2024. [PMID: 38320154 DOI: 10.1021/acsnano.3c10421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Simultaneous in situ detection of transcript and protein markers at the single-cell level is essential for gaining a better understanding of tumor heterogeneity and for predicting and monitoring treatment responses. However, the limited accessibility to advanced 3D imaging techniques has hindered their rapid implementation. Here, we present a 3D single-cell imaging technique, termed 3D digital rolling circle amplification (4DRCA), capable of the multiplexed and amplified simultaneous digital quantification of single-cell RNAs and proteins using standard fluorescence microscopy and off-the-shelf reagents. We generated spectrally distinguishable DNA amplicons from molecular markers through an integrative protocol combining single-cell RNA and protein assays and directly enumerated the amplicons by leveraging an open-source algorithm for 3D deconvolution with a custom-built automatic gating algorithm. With 4DRCA, we were able to simultaneously quantify surface protein markers and cytokine transcripts in T-lymphocytes. We also show that 4DRCA can distinguish BCR-ABL1 fusion transcript positive B-cell acute lymphoblastic leukemia cells with or without CD19 protein expression. The accessibility and extensibility of 4DRCA render it broadly applicable to other cell-based diagnostic workflows, enabling sensitive and accurate single-cell RNA and protein profiling.
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Affiliation(s)
- Suyeon Shin
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Yoon-Jin Kim
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Hyo Geun Yun
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Republic of Korea
| | - Haerim Chung
- Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Hyunsoo Cho
- Division of Hematology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Sungyoung Choi
- Department of Electronic Engineering, Hanyang University, Seoul 04763, Republic of Korea
- Department of Biomedical Engineering, Hanyang University, Seoul 04763, Republic of Korea
- Department of Healthcare Digital Engineering, Hanyang University, Seoul 04763, Republic of Korea
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2
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Dai H, Zhang J, Wu Y, Zhao J, Liu C, Cheng Y. Tyramine-Invertase Bioconjugate-Amplified Personal Glucose Meter Signaling for Ultrasensitive Immunoassay. Anal Chem 2024; 96:1789-1794. [PMID: 38230634 DOI: 10.1021/acs.analchem.3c05140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
Highly sensitive and facile detection of low levels of protein markers is of great significance for the early diagnosis and efficacy monitoring of diseases. Herein, aided by an efficient tyramine-signal amplification (TSA) mechanism, we wish to report a simple but ultrasensitive immunoassay with signal readout on a portable personal glucose meter (PGM). In this study, the bioconjugates of tyramine and invertase (Tyr-inv), which act as the critical bridge to convert and amplify the protein concentration information into glucose, are prepared following a click chemistry reaction. Then, in the presence of a target protein, the sandwich immunoreaction between the immobilized capture antibody, the target protein, and the horseradish peroxidase (HRP)-conjugated detection antibody is specifically performed in a 96-well microplate. Subsequently, the specifically loaded HRP-conjugated detection antibodies will catalyze the amplified deposition of a large number of Tyr-inv molecules onto adjacent proteins through highly efficient TSA. Then, the deposited invertase, whose dosage can faithfully reflect the original concentration of the target protein, can efficiently convert sucrose to glucose. The amount of finally produced glucose is simply quantified by the PGM, realizing the highly sensitive detection of trace protein markers such as the carcinoembryonic antigen and alpha fetoprotein antigen at the fg/mL level. This method is simple, cost-effective, and ultrasensitive without the requirement of sophisticated instruments or specialized laboratory equipment, which may provide a universal and promising technology for highly sensitive immunoassay for in vitro diagnosis of diseases.
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Affiliation(s)
- Hui Dai
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis (Hebei University), Ministry of Education; Key Laboratory of Analytical Science and Technology of Hebei Province; State Key Laboratory of New Pharmaceutical Preparations and Excipients; College of Chemistry and Materials Science, Hebei University, Baoding 071002, Hebei, P. R. China
| | - Jiangyan Zhang
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis (Hebei University), Ministry of Education; Key Laboratory of Analytical Science and Technology of Hebei Province; State Key Laboratory of New Pharmaceutical Preparations and Excipients; College of Chemistry and Materials Science, Hebei University, Baoding 071002, Hebei, P. R. China
| | - Yating Wu
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis (Hebei University), Ministry of Education; Key Laboratory of Analytical Science and Technology of Hebei Province; State Key Laboratory of New Pharmaceutical Preparations and Excipients; College of Chemistry and Materials Science, Hebei University, Baoding 071002, Hebei, P. R. China
| | - Jingyu Zhao
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis (Hebei University), Ministry of Education; Key Laboratory of Analytical Science and Technology of Hebei Province; State Key Laboratory of New Pharmaceutical Preparations and Excipients; College of Chemistry and Materials Science, Hebei University, Baoding 071002, Hebei, P. R. China
| | - Chenghui Liu
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education; Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi'an, Shaanxi Province 710119, P. R. China
| | - Yongqiang Cheng
- Key Laboratory of Medicinal Chemistry and Molecular Diagnosis (Hebei University), Ministry of Education; Key Laboratory of Analytical Science and Technology of Hebei Province; State Key Laboratory of New Pharmaceutical Preparations and Excipients; College of Chemistry and Materials Science, Hebei University, Baoding 071002, Hebei, P. R. China
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3
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Gao C, Zhang T, Wei Y, Liu Q, Ma L, Gao M, Zhao X, Wang Y, Chen D, Sun L, Wang J, Chen J. Development of a Microfluidic Flow Cytometer with a Uniform Optical Field (Uni-μFCM) Enabling Quantitative Analysis of Single-Cell Proteins and Its Applications in Leukemia Gating, Tumor Classification, and Hierarchy of Cancer Stem Cells. ACS Sens 2023; 8:3498-3509. [PMID: 37602731 PMCID: PMC10521140 DOI: 10.1021/acssensors.3c01060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 08/02/2023] [Indexed: 08/22/2023]
Abstract
Fast and quantitative estimation of single-cell proteins with various distribution patterns remains a technical challenge. Here, a microfluidic flow cytometer with a uniform optical field (Uni-μFCM) was developed, which enabled the translation of multicolor fluorescence signals of bound antibodies into targeted protein numbers with arbitrary distributions of biological cells. As the core of Uni-μFCM, a uniform optical field for optical excitation and fluorescence detection was realized by adopting a microfabricated metal window to shape the optical beam for excitation, which was modeled and validated by both numerical simulation and experimental characterization. After the validation of Uni-μFCM in single-cell protein quantification by measuring single-cell expressions of three transcriptional factors from four cell lines of variable sizes and origins, Uni-μFCM was applied to (1) quantify membrane and cytoplasmic markers of myeloid and lymphocytic leukocytes to classify cell lines and normal and patient blood samples; (2) measure single-cell expressions of key cytokines affiliated with gene stabilities, differentiating paired oral and colon tumor cell lines with varied malignancies, and (3) quantify single-cell stemming markers of liver tumor cell lines, cell subtypes, and liver patient samples to determine a variety of lineage hierarchy. By quantitatively assessing complex cellular phenotypes, Uni-μFCM substantially expanded the phenotypic space accessible to single-cell applications in leukemia gating, tumor classification, and hierarchy determination of cancer stem cells.
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Affiliation(s)
- Chiyuan Gao
- State
Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing100190, People’s Republic of China
- School
of Future Technology, University of Chinese
Academy of Sciences, Beijing100049, People’s
Republic of China
| | - Ting Zhang
- State
Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing100190, People’s Republic of China
- School
of Future Technology, University of Chinese
Academy of Sciences, Beijing100049, People’s
Republic of China
| | - Yuanchen Wei
- State
Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing100190, People’s Republic of China
| | - Qinghua Liu
- State
Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing100190, People’s Republic of China
- School
of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Liangliang Ma
- State
Key Laboratory of Molecular Oncology,National
Cancer Center/National Clinical Research Center for Cancer/Cancer
Hospital Chinese Academy of Medical Sciences and Peking Union Medical
College, Beijing100021, People’s Republic
of China
| | - Mengge Gao
- Peking
University People’s Hospital, Peking University Institute of
Hematology, National Clinical Research Center for Hematologic Disease,
Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Beijing100044, People’s Republic of China
| | - Xiaosu Zhao
- Peking
University People’s Hospital, Peking University Institute of
Hematology, National Clinical Research Center for Hematologic Disease,
Beijing Key Laboratory of Hematopoietic Stem Cell Transplantation, Beijing100044, People’s Republic of China
| | - Yixiang Wang
- Peking
University
Hospital of Stomatology, Beijing100081, People’s
Republic of China
| | - Deyong Chen
- State
Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing100190, People’s Republic of China
- School
of Future Technology, University of Chinese
Academy of Sciences, Beijing100049, People’s
Republic of China
- School
of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Lichao Sun
- State
Key Laboratory of Molecular Oncology,National
Cancer Center/National Clinical Research Center for Cancer/Cancer
Hospital Chinese Academy of Medical Sciences and Peking Union Medical
College, Beijing100021, People’s Republic
of China
| | - Junbo Wang
- State
Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing100190, People’s Republic of China
- School
of Future Technology, University of Chinese
Academy of Sciences, Beijing100049, People’s
Republic of China
- School
of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
| | - Jian Chen
- State
Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing100190, People’s Republic of China
- School
of Future Technology, University of Chinese
Academy of Sciences, Beijing100049, People’s
Republic of China
- School
of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing100049, People’s Republic of China
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Wu W, Xia S, Zhao M, Ping J, Lin JM, Hu Q. Colorimetric liquid crystal-based assay for the ultrasensitive detection of AFB1 assisted with rolling circle amplification. Anal Chim Acta 2022; 1220:340065. [DOI: 10.1016/j.aca.2022.340065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/28/2022] [Accepted: 06/07/2022] [Indexed: 11/17/2022]
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5
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Advances in nucleic acid amplification techniques (NAATs): COVID-19 point-of-care diagnostics as an example. Biosens Bioelectron 2022; 206:114109. [PMID: 35245867 DOI: 10.1016/j.bios.2022.114109] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 01/24/2022] [Accepted: 02/15/2022] [Indexed: 12/13/2022]
Abstract
Achieving superhigh sensitivity is the ultimate goal for bio-detection in modern analytical science and life science. Among variable signal amplification strategies, nucleic acid amplification technologies are revolutionizing the field of bio-detection, providing greater possibilities in novel diagnosis achieving high efficiency, specificity, and cost-effectiveness. Nucleic acid amplification techniques (NAATs), such as Polymerase Chain Reaction (PCR), Rolling Circle Amplification (RCA), Loop-Mediated Isothermal Amplification (LAMP), Recombinase Polymerase Amplification (RPA), CRISPR-related amplification, and others are dominating methods employed in research and clinical settings. They each provide distinctively unique features that can offer desirable performance in terms of sensitivity, specificity, simplicity, stability, and cost. NAATs are in unmet demand in molecular diagnosis, especially in point-of-care scenario. This review will discuss the principles and recent advancements of each NAAT, respectively, revealing their strengths and challenges in achieving rapid and accurate bio-detection with a focus on point-of-care diagnosis. Furthermore, this review will explore the application of each of the technologies through the contemporary COVID-19 pandemic, analyzing their ability in point-of-care diagnosis of the COVID-19 with high sensitivity to emphasize significance of developing NAATs based methods in battling COVID-19. Finally, advantages and potentials of each NAAT in enhancements of sensitivity and specificity in bio-detection from bench side to the bedside will be discussed, aiming for full exploitation of capability of each NAAT. This review will provide novel aspects in the selection and combination of usages of various NAATs based on their distinctive characteristics and limitations. A possible advancing direction of future accurate POCT is also proposed.
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6
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Soares RRG, Madaboosi N, Nilsson M. Rolling Circle Amplification in Integrated Microsystems: An Uncut Gem toward Massively Multiplexed Pathogen Diagnostics and Genotyping. Acc Chem Res 2021; 54:3979-3990. [PMID: 34637281 PMCID: PMC8567418 DOI: 10.1021/acs.accounts.1c00438] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The development of robust methods allowing the precise detection of specific nucleic acid sequences is of major societal relevance, paving the way for significant advances in biotechnology and biomedical engineering. These range from a better understanding of human disease at a molecular level, allowing the discovery and development of novel biopharmaceuticals and vaccines, to the improvement of biotechnological processes providing improved food quality and safety, efficient green fuels, and smart textiles. Among these applications, the significance of pathogen diagnostics as the main focus of this Account has become particularly clear during the recent SARS-CoV-2 pandemic. In this context, while RT-PCR is the gold standard method for unambiguous detection of genetic material from pathogens, other isothermal amplification alternatives circumventing rapid heating-cooling cycles up to ∼95 °C are appealing to facilitate the translation of the assay into point-of-care (PoC) analytical platforms. Furthermore, the possibility of routinely multiplexing the detection of tens to hundreds of target sequences with single base pair specificity, currently not met by state-of-the-art methods available in clinical laboratories, would be instrumental along the path to tackle emergent viral variants and antimicrobial resistance genes. Here, we advocate that padlock probes (PLPs), first reported by Nilsson et al. in 1994, coupled with rolling circle amplification (RCA), termed here as PLP-RCA, is an underexploited technology in current arena of isothermal nucleic acid amplification tests (NAATs) providing an unprecedented degree of multiplexing, specificity, versatility, and amenability to integration in miniaturized PoC platforms. Furthermore, the intrinsically digital amplification of PLP-RCA retains spatial information and opens new avenues in the exploration of pathogenesis with spatial multiomics analysis of infected cells and tissue.The Account starts by introducing PLP-RCA in a nutshell focusing individually on the three main assay steps, namely, (1) PLP design and ligation mechanism, (2) RCA after probe ligation, and (3) detection of the RCA products. Each subject is touched upon succinctly but with sufficient detail for the reader to appreciate some assay intricacies and degree of versatility depending on the analytical challenge at hand. After familiarizing the reader with the method, we discuss specific examples of research in our group and others using PLP-RCA for viral, bacterial, and fungal diagnostics in a variety of clinical contexts, including the genotyping of antibiotic resistance genes and viral subtyping. Then, we dissect key developments in the miniaturization and integration of PLP-RCA to minimize user input, maximize analysis throughput, and expedite the time to results, ultimately aiming at PoC applications. These developments include molecular enrichment for maximum sensitivity, spatial arrays to maximize analytical throughput, automation of liquid handling to streamline the analytical workflow in miniaturized devices, and seamless integration of signal transduction to translate RCA product titers (and ideally spatial information) into a readable output. Finally, we position PLP-RCA in the current landscape of NAATs and furnish a systematic Strengths, Weaknesses, Opportunities and Threats analysis to shine light upon unpolished edges to uncover the gem with potential for ubiquitous, precise, and unbiased pathogen diagnostics.
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Affiliation(s)
- Ruben R. G. Soares
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 17165 Solna, Sweden
- Division of Nanobiotechnology, Department of Protein Science, Science for Life Laboratory, KTH Royal Institute of Technology, 17165 Solna, Sweden
| | - Narayanan Madaboosi
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 17165 Solna, Sweden
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, 600036 Tamil Nadu, India
| | - Mats Nilsson
- Department of Biochemistry and Biophysics, Science for Life Laboratory, Stockholm University, 17165 Solna, Sweden
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7
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Chen Z, Ma L, Bu S, Zhang W, Chen J, Li Z, Hao Z, Wan J. CRISPR/Cas12a and immuno-RCA based electrochemical biosensor for detecting pathogenic bacteria. J Electroanal Chem (Lausanne) 2021. [DOI: 10.1016/j.jelechem.2021.115755] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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8
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Cao D, Wu S, Xi C, Li D, Zhu K, Zhang Z, Gong H, Luo Q, Yang J. Preparation of long single-strand DNA concatemers for high-level fluorescence in situ hybridization. Commun Biol 2021; 4:1224. [PMID: 34697406 PMCID: PMC8545947 DOI: 10.1038/s42003-021-02762-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 10/07/2021] [Indexed: 12/02/2022] Open
Abstract
Fluorescence in situ hybridization (FISH) is a powerful tool to visualize transcripts in fixed cells and tissues. Despite the recent advances in FISH detection methods, it remains challenging to achieve high-level FISH imaging with a simple workflow. Here, we introduce a method to prepare long single-strand DNA concatemers (lssDNAc) through a controllable rolling-circle amplification (CRCA). Prepared lssDNAcs are used to develop AmpFISH workflows. In addition, we present its applications in different scenarios. AmpFISH shows the following advantages: 1) enhanced FISH signal-to-noise ratio (SNR) up to 160-fold compared with single-molecule FISH; 2) simultaneous detection of FISH signals and fluorescent proteins or immunofluorescence (IF) in tissues; 3) simple workflows; and 4) cost-efficiency. In brief, AmpFISH provides convenient and versatile tools for sensitive RNA/DNA detection and to gain useful information on cellular molecules using simple workflows.
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Affiliation(s)
- Dongjian Cao
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Sa Wu
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Caili Xi
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Dong Li
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Kaiheng Zhu
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Zhihong Zhang
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Hui Gong
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China
| | - Qingming Luo
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
- School of Biomedical Engineering, Hainan University, Haikou, 570228, China.
| | - Jie Yang
- Britton Chance Center and MoE Key Laboratory for Biomedical Photonics, School of Engineering Sciences, Wuhan National Laboratory for Optoelectronics-Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
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9
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He JY, Chen ZH, Deng HL, Yuan R, Xu WJ. Antibody-powered DNA switches to initiate the hybridization chain reaction for the amplified fluorescence immunoassay. Analyst 2021; 146:5067-5073. [PMID: 34297024 DOI: 10.1039/d1an01045j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Designing antibody-powered DNA nanodevice switches is crucial and fascinating to perform a variety of functions in response to specific antibodies as regulatory inputs, achieving highly sensitive detection by integration with simple amplified methods. In this work, we report a unique DNA-based conformational switch, powered by a targeted anti-digoxin mouse monoclonal antibody (anti-Dig) as a model, to rationally initiate the hybridization chain reaction (HCR) for enzyme-free signal amplification. As a proof-of-concept, both a fluorophore Cy3-labeled reporter hairpin (RH) in the 3' terminus and a single-stranded helper DNA (HS) were individually hybridized with a recognition single-stranded DNA (RS) modified with Dig hapten, while the unpaired loop of RH was hybridized with the exposed 3'-toehold of HS, isothermally self-assembling an intermediate metastable DNA structure. The introduction of target anti-Dig drove the concurrent conjugation with two tethered Dig haptens, powering the directional switch of this DNA structure into a stable conformation. In this case, the unlocked 3'-stem of RH was implemented to unfold the 5'-stem of the BHQ-2-labeled quench hairpin (QH), rationally initiating the HCR between them by the overlapping complementary hybridization. As a result, numerous pairs of Cy3 and BHQ-2 in the formed long double helix were located in spatial proximity. In response to this, the significant quenching of the fluorescence intensity of Cy3 by BHQ-2 was dependent on the variable concentration of anti-Dig, achieving a highly sensitive quantification down to the picomolar level based on a simplified protocol integrated with enzyme-free amplification.
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Affiliation(s)
- Jia-Yang He
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.
| | - Ze-Hui Chen
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.
| | - Hui-Lin Deng
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.
| | - Ruo Yuan
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.
| | - Wen-Ju Xu
- Key Laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R. China.
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