Ting Huang, Naihan Huang, Qianying Zhou, Baoping Xie, Wenjun Duan, Bin Sun, Zong Dai, Jun Chen, Jin-Xiang Chen
{"title":"Target-Triggered Cascaded Self-Feedback DNAzyme Circuit Loaded in ZIF-8 for Highly Sensitive miRNA Imaging in Living Cells","authors":"Ting Huang, Naihan Huang, Qianying Zhou, Baoping Xie, Wenjun Duan, Bin Sun, Zong Dai, Jun Chen, Jin-Xiang Chen","doi":"10.1021/acs.analchem.5c01163","DOIUrl":"https://doi.org/10.1021/acs.analchem.5c01163","url":null,"abstract":"The highly sensitive and rapid imaging of miRNA in living cells promises to advance our understanding of diseases and promote their diagnosis and treatment. To enhance the sensitivity of miRNA imaging, a series of cascade signal amplification strategies based on enzyme-free methods have been developed. However, these cascaded amplification strategies involve complex designs and multiple amplification mechanisms, leading to potential side effects. Herein, we have developed a novel hairpins@ZIF-8 nanosystem by rationally integrating ZIF-8 with a cascaded self-feedback DNAzyme circuit (CSDC), achieving highly sensitive and rapid imaging of miRNA in living cells. ZIF-8 facilitates the efficient transfection of nucleic acid probes into cells and provides the necessary cofactor ions for CSDC. The developed CSDC possesses exponential amplification based solely on the DNAzyme mechanism. Benefiting from the exponential amplification efficiency, the CSDC exhibited higher sensitivity than traditional DNAzyme-based amplification, with a detection limit of 2.28 fM, approximately 10<sup>5</sup> times more sensitive than traditional DNAzyme-based amplification. This hairpins@ZIF-8 nanosystem demonstrated strong practical application capabilities, effectively reflecting fluctuations in intracellular miRNA levels and successfully distinguishing between normal and tumor cells based on miRNA expression differences. It could also be applied for in vivo miRNA imaging. This proposed strategy is anticipated to pave the way for innovative amplification approaches and serve as a vital instrument in miRNA-related research, diagnosis, and treatment.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"72 3 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143737053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jie Gao, Yucun Zhang, Rui Zhu, Mu Li, Fei Xie, Changyin Li, Bingqian Li, Yungang Zhang
{"title":"Optical Sensing System Based on Bidirectional Self-Correction Technology: An Online Detection Method for Carbon Disulfide and Sulfur Dioxide in Gas-Insulated Switchgear","authors":"Jie Gao, Yucun Zhang, Rui Zhu, Mu Li, Fei Xie, Changyin Li, Bingqian Li, Yungang Zhang","doi":"10.1021/acs.analchem.5c00807","DOIUrl":"https://doi.org/10.1021/acs.analchem.5c00807","url":null,"abstract":"Carbon disulfide (CS<sub>2</sub>) and sulfur dioxide (SO<sub>2</sub>) are typical indicative gases for the early warning and diagnosis of faults in gas-insulated switchgear. In this study, an optical sensing system is reported for online detection of CS<sub>2</sub> and SO<sub>2</sub> based on a bidirectional self-correction technology (BSCT). First, the differential absorption signals of CS<sub>2</sub> and SO<sub>2</sub> in the wavelength range of 195–230 nm are obtained using the UV differential optical absorption spectroscopy (UV-DOAS) technique. On this basis, a BSCT is proposed to decouple the spectral lines that exhibit significant overlap. This method primarily employs bidirectional difference spectroscopy to mutually correct the spectra of CS<sub>2</sub> and SO<sub>2</sub>, combined with spectral reconstruction to extract the single-component absorption signals of CS<sub>2</sub> and SO<sub>2</sub> from the mixed gas spectra. Furthermore, the effectiveness of this novel decoupling technique is validated by comparing the decoupling results with the absorption spectra of single-component standard gases at corresponding concentrations. Finally, the quantitative relationships between the concentrations of target gases (CS<sub>2</sub>, SO<sub>2</sub>) and the optical parameters are modeled using the least-squares method. The experimental results show that the mean absolute percentage errors of CS<sub>2</sub> (19.00–3735.35 ppb) and SO<sub>2</sub> (0.19–38.77 ppm) are 0.543 and 0.521%, respectively. At an effective optical range of 50 cm, the system achieves the lowest detection limits of 0.5 ppb for CS<sub>2</sub> and 12 ppb for SO<sub>2</sub>, representing the best results reported to date for the online detection of CS<sub>2</sub> and SO<sub>2</sub> in the ppb-ppm range.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"72 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Aggregation-Induced Room Temperature Phosphorescence Probe for the Efficient and Selective Detection of Heparin and Protamine","authors":"Priyam Das, Sampurna Routray, Malay Kumar Baroi, Tanushree Das, Debapratim Das","doi":"10.1021/acs.analchem.5c00382","DOIUrl":"https://doi.org/10.1021/acs.analchem.5c00382","url":null,"abstract":"Heparin is a vital macromolecule that regulates blood coagulation, while protamine is an essential polypeptide clinically used to counteract heparin overdose. Detecting both heparin and its antidote protamine under physiological conditions is crucial for biological and clinical applications. This report introduces a cucurbituril[8] (CB[8])-based phosphorescent probe for their detection. The method employs a nanoassembly induced phosphorescence switch-on mechanism for heparin sensing and a disassembly induced phosphorescence switch-off approach for protamine detection. An arginine-rich guest forms a supramolecular complex with heparin, enhancing phosphorescence under secondary confinement and enabling its detection. Conversely, protamine sulfate, as a stronger competitor for heparin, disrupts the probe-heparin aggregates, leading to emission quenching and protamine sensing. This sensor demonstrated high selectivity in detecting both analytes in biological samples, such as human blood serum and urine. The detection limits for heparin and protamine were determined to be 61 and 82 ng/mL in 10% HBS, respectively.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"20 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juan Song, Yue Zheng, Xiaodan Huang, Xiyuan Yu, Rui Su, Zhi Zhu, Chaoyong Yang, Zengpeng Li, Yu Jiang, Huimin Zhang
{"title":"Enhancing Thermodynamic and Kinetic Performance of Microfluidic Interface-Based Circulating Fetal Cell Isolation for Noninvasive Prenatal Testing","authors":"Juan Song, Yue Zheng, Xiaodan Huang, Xiyuan Yu, Rui Su, Zhi Zhu, Chaoyong Yang, Zengpeng Li, Yu Jiang, Huimin Zhang","doi":"10.1021/acs.analchem.5c00711","DOIUrl":"https://doi.org/10.1021/acs.analchem.5c00711","url":null,"abstract":"Multivalent strategies have been widely applied in the microfluidic interface to boost the capture efficiency of target cells. However, achieving a balance between binding kinetics and thermodynamics in existing multivalent affinity interfaces remains challenging. Here, we propose a synergistic <b>A</b>ptamer-nanobody hetero-<b>M</b>ultivalency <b>P</b>rogrammable magnetic fluid microfluidic chip (<b>AMP-chip</b>) which utilizes the combined advantages of ligands to enhance both thermodynamic and kinetic properties of the capture interface. The AMP-chip integrates two distinct noninterfering recognition molecules: one with high affinity and another with rapid binding capability, both of which are assembled onto nanomagnetic beads. This integration achieves intermolecular complementarity, effectively enhancing the binding kinetics and thermodynamic stability. We chose mutually noninterfering CD71 recognition targets, a high-affinity nanobody (NB) and a rapid-binding aptamer (XQ 2d), and fully utilized the respective advantages of these ligands to facilitate rapid and tight recognition of the CD71 receptor on target cells. By integrating a herringbone microarray into an AMP-chip to further increase the cell–ligand interaction, we significantly improved the sensitivity and accuracy of circulating nucleated red blood cell (cNRBC) isolation from the peripheral blood mononuclear cells (PBMCs) of pregnant women. Additionally, the ligands were primarily fixed to the chip by magnetic force without chemical bonding, enabling nondestructive cell release and preserving high cell viability for subsequent molecular analyses. Overall, this approach offers a novel thermodynamic–kinetic synergistic heteromultivalency interface with significant potential for clinical applications.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"183 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ondřej Peterka, Yasmin Kadyrbekova, Robert Jirásko, Zuzana Lásko, Bohuslav Melichar, Michal Holčapek
{"title":"Novel Charge-Switch Derivatization Method Using 3-(Chlorosulfonyl)benzoic Acid for Sensitive RP-UHPLC/MS/MS Analysis of Acylglycerols, Sterols, and Prenols","authors":"Ondřej Peterka, Yasmin Kadyrbekova, Robert Jirásko, Zuzana Lásko, Bohuslav Melichar, Michal Holčapek","doi":"10.1021/acs.analchem.4c06496","DOIUrl":"https://doi.org/10.1021/acs.analchem.4c06496","url":null,"abstract":"Chemical derivatization involves the reaction of an analyte with a derivatization agent to modify its structure, improving the peak shape, chromatographic performance, structural analysis, ionization efficiency, and sensitivity. A novel derivatization method using 3-(chlorosulfonyl)benzoic acid is developed for the determination of monoacylglycerols, diacylglycerols, free sterols, and tocopherols using the reversed-phase ultra-high-performance liquid chromatography–tandem mass spectrometry (RP-UHPLC/MS/MS) method in the negative ion mode. The chromatographic and mass spectrometric properties of derivatized lipids are investigated by using 29 lipid standards spanning four lipid classes. The derivatization process is optimized using pooled plasma spiked by 9 internal standards, achieving an optimal yield with a reaction time of 40 min at 60 °C. The stability of the derivatives is confirmed, with short-term stability maintained for 10 h at 4 °C and long-term stability preserved for 5 days at −80 °C. The repeatability and reproducibility are verified by one/two operator(s), which underscores the simplicity and robustness of the method, and calibration curves with high linear regression coefficients illustrate the accuracy of the method. The derivatization approach, which combines RP-UHPLC/MS/MS and the use of specific fragmentation patterns, significantly reduces limits of detection, reaching 15–25 pmol/mL for free sterols in plasma. The optimized method is applied to the analysis of human plasma, leading to the identification of 92 lipid species in the targeted lipid classes. This represents a substantial improvement in sensitivity and detection capabilities compared to those of previously reported methods.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"183 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Digital Redepleted of Stimulated Emission Depletion Microscopy for Noise Reduction and Resolution Improvement","authors":"Xinwei Gao, Yong Guo, Luwei Wang, Yue Chen, Xiangcong Xu, Lukui Xu, Xiaoyu Weng, Wei Yan, Junle Qu","doi":"10.1021/acs.analchem.5c00101","DOIUrl":"https://doi.org/10.1021/acs.analchem.5c00101","url":null,"abstract":"Stimulated emission depletion microscopy (STED) achieves resolution beyond the diffraction limit by employing a donut-shaped depletion laser that selectively reduces fluorescence at the periphery of the excitation area. The imaging quality of STED microscopy is closely tied to minimizing the intermediate light from the ring-depletion laser. In this study, we introduce a method termed “digital redepleted STED,” which uses frequency domain filtering to generate an optimal donut profile by subtracting the “perfect donut” signal from the original STED data. This approach effectively reduces background noise and enhances the STED resolution. Through simulation experiments, we demonstrate that digitally redepleted STED doubled the resolution. This method is compatible with a wide range of biological samples and can be adapted for two-organelle-structure STED and 3D STED applications. We compare the performance of digitally redepleted STED with that of digitally enhanced STED (De STED) and deconvolution methods (STED Decon) in terms of the signal-to-background ratio (SBR) and resolution as evaluation metrics, and we find that our method doubled the resolution and SBR for different samples compared with origin STED. Our results indicate that digitally redepleted STED outperforms both De STED and STED Decon for complicated sample like mitochondria. We anticipate that the digitally redepleted STED will have broad applicability due to its enhanced resolution, improved SBR, and ease of implementation.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"26 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhihao Zhang, Huaiwen Cang, Qingyun Li, Yi Yu, Huimin Jiao, Yuanyuan Xie, Shan Deng, Jichun Jiang, Lei Hua, Haiyang Li, Hang Li
{"title":"Miniature Thermoelectric Cooler for Long-Term Stable Dehydration for On-Site Breath Analysis by Direct Inlet Photoionization Ion Mobility Spectrometry and Mass Spectrometry","authors":"Zhihao Zhang, Huaiwen Cang, Qingyun Li, Yi Yu, Huimin Jiao, Yuanyuan Xie, Shan Deng, Jichun Jiang, Lei Hua, Haiyang Li, Hang Li","doi":"10.1021/acs.analchem.5c00138","DOIUrl":"https://doi.org/10.1021/acs.analchem.5c00138","url":null,"abstract":"Rapid and highly frequent measurements of exhaled breath hold significant value for disease diagnosis and exposure assessments. Direct inlet mass spectrometry and ion mobility spectrometry demonstrate great potential for on-site breath analysis, but their accuracy and sensitivity are notably affected by the high humidity in the breath samples. A miniature and continuous dehydration device based on dual-switching thermoelectric cold traps has been developed to efficiently reduce the humidity of breath gas from saturation to relative humidity of 4.3%, and a subcooling compensation method was adopted to eliminate the humidity fluctuations when switching the two cold traps to remove the condensed water in the trap, which could achieve a stable outlet humidity with RSD of 8.2% regardless of inlet humidity variations. The performance and profits of the miniature dehydration device for on-site analysis of breath samples have been tested by coupling with direct inlet photoionization ion mobility spectrometry and time-of-flight mass spectrometry. Trace breath acetone could be directly measured, and its concentration profiles over an 8 h period in fasting volunteers could be continuously monitored every 30 s. Furthermore, the <i>m</i>/<i>z</i> peaks from chlorinated hydrocarbons in exhaled breath samples were clearly identified after passing the dehydration device, which can be used for an occupational health assessment of the widely used halocarbon solvents.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"59 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A New Chemiluminescence-Based Rapid Diagnostic Testing Platform with Sequential Dual-Flow Strips for Cardiac Troponin I (cTnI)","authors":"Heeyeong Jang, Supreeth Setty, Chong Ahn","doi":"10.1021/acs.analchem.4c06427","DOIUrl":"https://doi.org/10.1021/acs.analchem.4c06427","url":null,"abstract":"Although the most commonly used method for enhancing a limit of detection (LoD) in immunoassay is adopting chemiluminescence (CL), the liquid form of CL substrates has hindered its use for rapid diagnostic testing (RDT). In order to use the CL-based immunoassay in RDT with minimal user intervention, the liquid CL substrate should be converted to a dry form. In addition, a new RDT platform that is able to perform two sequential flows needs to be developed for the sequential flow control of the CL substrate. In this work, we have successfully developed a new dry form of CL substrate on the strip using a lyophilization process, as well as new lateral flow strips using an additional membrane pad for a time delay to achieve the desired sequential dual flows. Thus, on the dual-flow RDT strips, first the detection antibody conjugated with an enzyme flows over the test and control lines, and then the reconstituted CL substrate flows later. A hydrophilic PVDF membrane was selected as a pad material for the time delay to achieve the sequential dual flows through two flow paths, and flow introduction timing was functionally controlled to secure the time delay of approximately 5 minutes desired between the two flows. A CL-based cardiac troponin I (<i>cTnI</i>) assay was successfully performed on the new dual-flow RDT platform with a sample volume of 120 μL, achieving a LoD of 100 pg/mL. The achieved LoD is better than those possible with most of the currently available RDTs on the market. The new CL-based RDT platform with the capability of dual flows developed in this work can be used for numerous other immunodiagnostic platforms which need further high-sensitivity detection, envisaging a new RDT platform for point-of-care testing with further quantitative analysis.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"49 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Direct Detection of Natural-Abundance Low-γ Nuclei NMR Signals of Minute Quantities of Organic Solids","authors":"Zhiwei Yan, Jiangying Li, Hailu Zhang, Rongchun Zhang","doi":"10.1021/acs.analchem.4c06887","DOIUrl":"https://doi.org/10.1021/acs.analchem.4c06887","url":null,"abstract":"Low-γ nuclei signal enhancement in solid-state NMR spectroscopy is typically achieved via cross-polarization (CP) using abundant <sup>1</sup>H polarization in organic solids. Nevertheless, direct low-γ nuclei signal detection via a single CP process is quite challenging with minute quantities of samples due to the extremely limited signal-to-noise ratio (SNR) of the acquired spectra. Herein, we demonstrated the robust performance of a multiple-contact CP experiment with multiple acquisition periods (MCP) in each transient scan, leading to several-fold SNR enhancement over a conventional single-CP experiment at fast MAS conditions with slightly increased experimental time. Spin thermodynamic analysis was further performed to achieve maximum SNR by adding the obtained <i>N</i><sub>max</sub> CP spectra from each transient, where <i>N</i><sub>max</sub> ∼ <i>T</i><sub>1ρ</sub>/<i>τ</i><sub>cw</sub>. Here, <i>T</i><sub>1ρ</sub> is the proton spin–lattice relaxation time in the rotating frame, and <i>τ</i><sub>cw</sub> is the total time of CP and a heteronuclear decoupling period. The theoretical analysis is in good agreement with experimental results, and more than 4.5-fold SNR enhancement can be achieved for the pharmaceutical danazol/vanillin cocrystals. Besides, MCP was also used for proton <i>T</i><sub>1</sub> and <i>T</i><sub>1ρ</sub> measurement with high-resolution <sup>13</sup>C detection, where both proton <i>T</i><sub>1</sub> and <i>T</i><sub>1ρ</sub> can serve as the spectral-editing basis to identify different immiscible components in complex molecular systems.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"10 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qing Dong, Xu Sun, Yuling Wang, Wei Zhang, Fan Feng, Dan Li, Jin Wang, Erkang Wang
{"title":"Enabling Sensitive Quantification of Exosomes Combining Aptamer-Based Rolling Circle Amplification and Silver Nanoparticles","authors":"Qing Dong, Xu Sun, Yuling Wang, Wei Zhang, Fan Feng, Dan Li, Jin Wang, Erkang Wang","doi":"10.1021/acs.analchem.4c06656","DOIUrl":"https://doi.org/10.1021/acs.analchem.4c06656","url":null,"abstract":"Exosomes carry various biological information and are abundant in body fluids, making them a promising noninvasive biomarker for disease diagnosis and prognosis. However, current detection methods have limitations in sensitivity, specificity, and cost effectiveness, hindering their clinical application. To address these challenges, we have developed a fast, accurate, and cost-effective method for detecting exosomes with high sensitivity and specificity, making it ideal for clinical applications. Clusters of differentiation 63 (CD63) aptamer with its complementary DNA (CD63 aptamer/cDNA) linked to streptavidin-coated magnetic beads (SA-MBs) are used as a capture probe. Exosomes with CD63 proteins can bind to the aptamer and release the cDNA, which initiates rolling circle amplification (RCA) to magnify the cDNA copies. The negatively charged RCA products induce the aggregation of positively charged spermine-modified silver nanoparticles (AgNPs) through electrostatic attraction. The aggregation of AgNPs can be observed visually with the naked eye or quantitatively analyzed using ultraviolet–visible (UV–vis) spectroscopy to determine the concentration of exosomes, with limits of detection of 4.0 × 10<sup>4</sup> particles/mL for visual observation and 800 particles/mL for UV–vis spectroscopy, respectively. The method has also been demonstrated for detecting the exosomes in serum samples, indicating its potential for clinical use in liquid biopsy.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":"99 1","pages":""},"PeriodicalIF":7.4,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143723759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}