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Dramatic enhancement of the detection limits of bioassays via ultrafast deposition of polydopamine


The ability to detect biomarkers with ultrahigh sensitivity radically transformed biology and disease diagnosis. However, owing to incompatibilities with infrastructure in current biological and medical laboratories, recent innovations in analytical technology have not yet been adopted broadly. Here, we report a simple, universal ‘add-on’ technology (dubbed EASE) that converts the ordinary sensitivities of common bioassays to extraordinary ones, and that can be directly plugged into the routine practices of current research and clinical laboratories. The assay relies on the bioconjugation capabilities and ultrafast and localized deposition of polydopamine at the target site, which permit a large number of reporter molecules to be captured and lead to detection-sensitivity enhancements exceeding three orders of magnitude. The application of EASE in the ELISA-based detection of the HIV antigen in blood from patients leads to a sensitivity lower than 3 fg ml−1. We also show that EASE allows for the direct visualization, in tissues, of the Zika virus and of low-abundance biomarkers related to neurological diseases and cancer immunotherapy.

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Figure 1: HRP-accelerated dopamine polymerization and deposition.
Figure 2: IHC-EASE single-cell staining.
Figure 3: IF-EASE cell staining.
Figure 4: Ultrasensitive suspension microarray enabled by EASE.
Figure 5: ELISA and lateral flow strips with EASE.
Figure 6: Early diagnosis of HIV in patient blood samples using ELISA-EASE.
Figure 7: Sensitive imaging of ZIKV in placenta and PD-L1 in FFPE pancreatic tumour specimens.


  1. 1

    Howes, P. D., Chandrawati, R. & Stevens, M. M. Colloidal nanoparticles as advanced biological sensors. Science 346, 1247390 (2014).

    Article  Google Scholar 

  2. 2

    Chan, W. C. & Nie, S. Quantum dot bioconjugates for ultrasensitive nonisotopic detection. Science 281, 2016–2018 (1998).

    CAS  Article  Google Scholar 

  3. 3

    Kelley, S. O. et al. Advancing the speed, sensitivity and accuracy of biomolecular detection using multi-length-scale engineering. Nat. Nanotech. 9, 969–980 (2014).

    CAS  Article  Google Scholar 

  4. 4

    Nam, J.-M., Thaxton, C. S. & Mirkin, C. A. Nanoparticle-based bio-bar codes for the ultrasensitive detection of proteins. Science 301, 1884–1886 (2003).

    CAS  Article  Google Scholar 

  5. 5

    Kosaka, P. M. et al. Detection of cancer biomarkers in serum using a hybrid mechanical and optoplasmonic nanosensor. Nat. Nanotech. 9, 1047–1053 (2014).

    CAS  Article  Google Scholar 

  6. 6

    Rodriguez-Lorenzo, L., de La Rica, R., Alvarez-Puebla, R. A., Liz-Marzan, L. M. & Stevens, M. M. Plasmonic nanosensors with inverse sensitivity by means of enzyme-guided crystal growth. Nat. Mater. 11, 604–607 (2012).

    CAS  Article  Google Scholar 

  7. 7

    He, L., Ozdemir, S. K., Zhu, J., Kim, W. & Yang, L. Detecting single viruses and nanoparticles using whispering gallery microlasers. Nat. Nanotech. 6, 428–432 (2011).

    CAS  Article  Google Scholar 

  8. 8

    Thomas, R. K. et al. Sensitive mutation detection in heterogeneous cancer specimens by massively parallel picoliter reactor sequencing. Nat. Med. 12, 852–855 (2006).

    CAS  Article  Google Scholar 

  9. 9

    Zheng, G., Patolsky, F., Cui, Y., Wang, W. U. & Lieber, C. M. Multiplexed electrical detection of cancer markers with nanowire sensor arrays. Nat. Biotechnol. 23, 1294–1301 (2005).

    CAS  Article  Google Scholar 

  10. 10

    Wu, G. et al. Bioassay of prostate-specific antigen (PSA) using microcantilevers. Nat. Biotechnol. 19, 856–860 (2001).

    CAS  Article  Google Scholar 

  11. 11

    Schallmeiner, E. et al. Sensitive protein detection via triple-binder proximity ligation assays. Nat. Methods 4, 135–137 (2007).

    CAS  Article  Google Scholar 

  12. 12

    Watanabe, R. et al. Arrayed lipid bilayer chambers allow single-molecule analysis of membrane transporter activity. Nat. Commun. 5, 4519 (2014).

    CAS  Article  Google Scholar 

  13. 13

    Ma, W. et al. Attomolar DNA detection with chiral nanorod assemblies. Nat. Commun. 4, 2689 (2013).

    Article  Google Scholar 

  14. 14

    Haun, J. B., Devaraj, N. K., Hilderbrand, S. A., Lee, H. & Weissleder, R. Bioorthogonal chemistry amplifies nanoparticle binding and enhances the sensitivity of cell detection. Nat. Nanotech. 5, 660–665 (2010).

    CAS  Article  Google Scholar 

  15. 15

    Vollmer, F. & Arnold, S. Whispering-gallery-mode biosensing: label-free detection down to single molecules. Nat. Methods 5, 591–596 (2008).

    CAS  Article  Google Scholar 

  16. 16

    Li, M., Tang, H. X. & Roukes, M. L. Ultra-sensitive NEMS-based cantilevers for sensing, scanned probe and very high-frequency applications. Nat. Nanotech. 2, 114–120 (2007).

    CAS  Article  Google Scholar 

  17. 17

    Cooper, M. A. et al. Direct and sensitive detection of a human virus by rupture event scanning. Nat. Biotechnol. 19, 833–837 (2001).

    CAS  Article  Google Scholar 

  18. 18

    Rissin, D. M. et al. Single-molecule enzyme-linked immunosorbent assay detects serum proteins at subfemtomolar concentrations. Nat. Biotechnol. 28, 595–599 (2010).

    CAS  Article  Google Scholar 

  19. 19

    Burst bubbles. Nature 526, 609–610 (2015).

  20. 20

    Lee, H., Dellatore, S. M., Miller, W. M. & Messersmith, P. B. Mussel-inspired surface chemistry for multifunctional coatings. Science 318, 426–430 (2007).

    CAS  Article  Google Scholar 

  21. 21

    Lee, H., Rho, J. & Messersmith, P. B. Facile conjugation of biomolecules onto surfaces via mussel adhesive protein inspired coatings. Adv. Mater. 21, 431–434 (2009).

    CAS  Article  Google Scholar 

  22. 22

    Soderhall, K. & Cerenius, L. Role of the prophenoloxidase-activating system in invertebrate immunity. Curr. Opin. Immunol. 10, 23–28 (1998).

    CAS  Article  Google Scholar 

  23. 23

    Cerenius, L. & Soderhall, K. The prophenoloxidase-activating system in invertebrates. Immunol. Rev. 198, 116–126 (2004).

    CAS  Article  Google Scholar 

  24. 24

    Weber, R. et al. Threshold of detection of Cryptosporidium oocysts in human stool specimens: evidence for low sensitivity of current diagnostic methods. J. Clin. Microbiol. 29, 1323–1327 (1991).

    CAS  PubMed  PubMed Central  Google Scholar 

  25. 25

    Mahler, M., Ngo, J. T., Schulte-Pelkum, J., Luettich, T. & Fritzler, M. J. Limited reliability of the indirect immunofluorescence technique for the detection of anti-Rib-P antibodies. Arth. Res. Ther. 10, R131 (2008).

    Article  Google Scholar 

  26. 26

    Zrazhevskiy, P., Sena, M. & Gao, X. Designing multifunctional quantum dots for bioimaging, detection, and drug delivery. Chem. Soc. Rev. 39, 4326–4354 (2010).

    CAS  Article  Google Scholar 

  27. 27

    Medintz, I. L., Uyeda, H. T., Goldman, E. R. & Mattoussi, H. Quantum dot bioconjugates for imaging, labelling and sensing. Nat. Mater. 4, 435–446 (2005).

    CAS  Article  Google Scholar 

  28. 28

    Zrazhevskiy, P. et al. Cross-platform DNA encoding for single-cell imaging of gene expression. Angew. Chem. Int. Ed. 55, 8975–8978 (2016).

    CAS  Article  Google Scholar 

  29. 29

    Battersby, B. J., Lawrie, G. A. & Trau, M. Optical encoding of microbeads for gene screening: alternatives to microarrays. Drug Discov. Today 6, 19–26 (2001).

    Article  Google Scholar 

  30. 30

    Braeckmans, K., De Smedt, S. C., Leblans, M., Pauwels, R. & Demeester, J. Encoding microcarriers: present and future technologies. Nat. Rev. Drug Discov. 1, 447–456 (2002).

    CAS  Article  Google Scholar 

  31. 31

    Nolan, J. P. & Sklar, L. A. Suspension array technology: evolution of the flat-array paradigm. Trends Biotechnol. 20, 9–12 (2002).

    CAS  Article  Google Scholar 

  32. 32

    Fulton, R. J., McDade, R. L., Smith, P. L., Kienker, L. J. & Kettman, J. R. Advanced multiplexed analysis with the FlowMetrixTM system. Clin. Chem. 43, 1749–1756 (1997).

    CAS  PubMed  Google Scholar 

  33. 33

    Dunbar, S. A. Applications of Luminex xMAP technology for rapid, high-throughput multiplexed nucleic acid detection. Clin. Chim. Acta 363, 71–82 (2006).

    CAS  Article  Google Scholar 

  34. 34

    Chan, W. C. et al. Luminescent quantum dots for multiplexed biological detection and imaging. Curr. Opin. Biotechnol. 13, 40–46 (2002).

    CAS  Article  Google Scholar 

  35. 35

    Han, M., Gao, X., Su, J. Z. & Nie, S. Quantum-dot-tagged microbeads for multiplexed optical coding of biomolecules. Nat. Biotechnol. 19, 631–635 (2001).

    CAS  Article  Google Scholar 

  36. 36

    Klein, D., Hurley, L. B., Merrill, D. & Quesenberry, C. P. Jr Review of medical encounters in the 5 years before a diagnosis of HIV-1 infection: implications for early detection. J. Acq. Immune Defic. Syndr. 32, 143–152 (2003).

    Article  Google Scholar 

  37. 37

    Fu, E. et al. Enhanced sensitivity of lateral flow tests using a two-dimensional paper network format. Analyt. Chem. 83, 7941–7946 (2011).

    CAS  Article  Google Scholar 

  38. 38

    Palella, F. J. et al. Survival benefit of initiating antiretroviral therapy in HIV-infected persons in different CD4+ cell strata. Ann. Intern. Med. 138, 620–626 (2003).

    Article  Google Scholar 

  39. 39

    Holodniy, M. et al. Relationship between antiretroviral prescribing patterns and treatment guidelines in treatment-naive HIV-1-infected US veterans (1992–2004). J. Acq. Immune Defic. Syndr 44, 20–29 (2007).

    Article  Google Scholar 

  40. 40

    Marks, G., Crepaz, N. & Janssen, R. S. Estimating sexual transmission of HIV from persons aware and unaware that they are infected with the virus in the USA. AIDs 20, 1447–1450 (2006).

    Article  Google Scholar 

  41. 41

    Miles, S. A. et al. Rapid serologic testing with immune-complex-dissociated HIV p24 antigen for early detection of HIV infection in neonates. New Engl. J. Med. 328, 297–302 (1993).

    CAS  Article  Google Scholar 

  42. 42

    Nishanian, P., Huskins, K. R., Stehn, S., Detels, R. & Fahey, J. L. A simple method for improved assay demonstrates that HIV p24 antigen is present as immune complexes in most sera from HIV-infected individuals. J. Infect. Dis. 162, 21–28 (1990).

    CAS  Article  Google Scholar 

  43. 43

    Marozsan, A. J. et al. Relationships between infectious titer, capsid protein levels, and reverse transcriptase activities of diverse human immunodeficiency virus type 1 isolates. J. Virol. 78, 11130–11141 (2004).

    CAS  Article  Google Scholar 

  44. 44

    Bale, T. L. & Vale, W. W. CRF and CRF receptors: role in stress responsivity and other behaviors. Annu. Rev. Pharmacol. Toxicol. 44, 525–557 (2004).

    CAS  Article  Google Scholar 

  45. 45

    Zorrilla, E. P., Logrip, M. L. & Koob, G. Corticotropin releasing factor: a key role in the neurobiology of addiction. Front. Neuroendocrinol. 35, 234–244 (2014).

    CAS  Article  Google Scholar 

  46. 46

    Van Pett, K. et al. Distribution of mRNAs encoding CRF receptors in brain and pituitary of rat and mouse. J. Comp. Neurol. 428, 191–212 (2000).

    CAS  Article  Google Scholar 

  47. 47

    Weathington, J. M. & Cooke, B. M. Corticotropin-releasing factor receptor binding in the amygdala changes across puberty in a sex-specific manner. Endocrinol. 153, 5701–5705 (2012).

    CAS  Article  Google Scholar 

  48. 48

    Waldorf, K. M. A. et al. Fetal brain lesions after subcutaneous inoculation of Zika virus in a pregnant nonhuman primate. Nat. Med. 22, 1256–1259 (2016).

    Article  Google Scholar 

  49. 49

    Keir, M. E. et al. PD-1 and its ligands in tolerance and immunity. Annu. Rev. Immunol. 26, 677–704 (2008).

    CAS  Article  Google Scholar 

  50. 50

    Brahmer, J. R. et al. Phase I study of single-agent anti–programmed death-1 (MDX-1106) in refractory solid tumors: safety, clinical activity, pharmacodynamics, and immunologic correlates. J. Clin. Oncol. 28, 3167–3175 (2010).

    CAS  Article  Google Scholar 

  51. 51

    Hamid, O. et al. Safety and tumor responses with lambrolizumab (anti–PD-1) in melanoma. New Engl. J. Med. 369, 134–144 (2013).

    CAS  Article  Google Scholar 

  52. 52

    Garon, E. B. et al. Pembrolizumab for the treatment of non-small-cell lung cancer. New Engl. J. Med. 372, 2018–2028 (2015).

    Article  Google Scholar 

  53. 53

    Rizvi, N. A. et al. Activity and safety of nivolumab, an anti-PD-1 immune checkpoint inhibitor, for patients with advanced, refractory squamous non-small-cell lung cancer (CheckMate 063): a phase 2, single-arm trial. Lancet Oncol. 16, 257–265 (2015).

    CAS  Article  Google Scholar 

  54. 54

    Nghiem, P. T. et al. PD-1 blockade with pembrolizumab in advanced Merkel-cell carcinoma. New Engl. J. Med. 374, 2542–2552 (2016).

    CAS  Article  Google Scholar 

  55. 55

    Wang, X. et al. PD-L1 expression in human cancers and its association with clinical outcomes. OncoTarg. Ther. 9, 5023–5039 (2016).

    CAS  Article  Google Scholar 

  56. 56

    Liu, Y., Ai, K. & Lu, L. Polydopamine and its derivative materials: synthesis and promising applications in energy, environmental, and biomedical fields. Chem. Rev. 114, 5057–5115 (2014).

    CAS  Article  Google Scholar 

  57. 57

    Li, J. et al. Stably doped conducting polymer nanoshells by surface initiated polymerization. Nano Lett. 15, 8217–8222 (2015).

    CAS  Article  Google Scholar 

  58. 58

    Sanford, C. A. et al. A central amygdala CRF circuit facilitates learning about weak threats. Neuron 93, 164–178 (2017).

    CAS  Article  Google Scholar 

  59. 59

    Zhao, H. et al. Structural basis of Zika virus-specific antibody protection. Cell 166, 1016–1027 (2016).

    CAS  Article  Google Scholar 

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This work was supported in part by the NIH (R21CA192985, R01AI100989, AI083019, AI104002, and AI060389) and the Department of Bioengineering at the University of Washington. J.L. thanks the Howard Hughes Medical Institute for a student fellowship. We are also grateful to B. Lutz and D. Leon for help with the lateral flow test, and P. Zrazhevskiy for discussions on immunostaining.

Author information




J.L. and X.G. conceived the idea and designed the project. J.L. and W.T. performed the majority of the experiments, with help from M.A.B. and L.S.Z. for CRF imaging in the brain, from M.A.D., K.M.A.W., M.G. and L.R. for ZIKA imaging, and R.H.P. for PD-L1 imaging. All authors were involved in data analysis. J.L., L.S.Z., K.M.A.W., M.G., L.R., R.H.P. and X.G. wrote the paper.

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Correspondence to Xiaohu Gao.

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The authors declare no competing financial interests.

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Li, J., Baird, M., Davis, M. et al. Dramatic enhancement of the detection limits of bioassays via ultrafast deposition of polydopamine. Nat Biomed Eng 1, 0082 (2017).

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