Radical polymerization inside living cells


Polymerization reactions conducted inside cells must be compatible with the complex intracellular environment, which contains numerous molecules and functional groups that could potentially prevent or quench polymerization reactions. Here we report a strategy for directly synthesizing unnatural polymers in cells through free radical photopolymerization using a number of biocompatible acrylic and methacrylic monomers. This offers a platform to manipulate, track and control cellular behaviour by the in cellulo generation of macromolecules that have the ability to alter cellular motility, label cells by the generation of fluorescent polymers for long-term tracking studies, as well as generate a variety of nanostructures within cells. It is remarkable that free radical polymerization chemistry can take place within such complex cellular environments. This demonstration opens up a multitude of new possibilities for how chemists can modulate cellular function and behaviour and for understanding cellular behaviour in response to the generation of free radicals.

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Fig. 1: Intracellular polymerization.
Fig. 2: HeLa cells that underwent intracellular polymerization were less migratory.
Fig. 3: Actin cytoskeleton organization was altered in polymerized HeLa cells.
Fig. 4: Polymerization of NaSS in HeLa cells.
Fig. 5: Co-polymerization of HPMA with AOTCRhB in HeLa cells.
Fig. 6: Polymerization of FMMA in HeLa cells.

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  1. 1.

    Nicolas, J., Mura, S., Brambilla, D., Mackiewicz, N. & Couvreur, P. Design, functionalization strategies and biomedical applications of targeted biodegradable/biocompatible polymer-based nanocarriers for drug delivery. Chem. Soc. Rev. 42, 1147–1235 (2013).

    CAS  Article  Google Scholar 

  2. 2.

    Green, J. J. & Elisseeff, J. H. Mimicking biological functionality with polymers for biomedical applications. Nature 540, 386–394 (2016).

    CAS  Article  Google Scholar 

  3. 3.

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

    Article  Google Scholar 

  4. 4.

    Tang, F., He, F., Cheng, H. & Li, L. Self-assembly of conjugated polymer-Ag@SiO2 hybrid fluorescent nanoparticles for application to cellular imaging. Langmuir 26, 11774–11778 (2010).

    CAS  Article  Google Scholar 

  5. 5.

    Tonga, G. Y. et al. Supramolecular regulation of bioorthogonal catalysis in cells using nanoparticle-embedded transition metal catalysts. Nat. Chem. 7, 597–603 (2015).

    CAS  Article  Google Scholar 

  6. 6.

    Yusop, R. M., Unciti-Broceta, A., Johansson, E. M. V., Sanchez-Martin, R. M. & Bradley, M. Palladium-mediated intracellular chemistry. Nat. Chem. 3, 239–243 (2011).

    CAS  Article  Google Scholar 

  7. 7.

    Collins, M. N. & Birkinshaw, C. Hyaluronic acid based scaffolds for tissue engineering—a review. Carbohydr. Polym. 92, 1262–1279 (2013).

    CAS  Article  Google Scholar 

  8. 8.

    Tasoglu, S. & Demirci, U. Bioprinting for stem cell research. Trends Biotechnol. 31, 10–19 (2013).

    CAS  Article  Google Scholar 

  9. 9.

    Hutmacher, D. W. Scaffolds in tissue engineering bone and cartilage. Biomaterials 21, 2529–2543 (2000).

    CAS  Article  Google Scholar 

  10. 10.

    Meyer, R. A. et al. Biodegradable nanoellipsoidal artificial antigen presenting cells for antigen specific T-cell activation. Small 11, 1519–1525 (2015).

    CAS  Article  Google Scholar 

  11. 11.

    Hu, C.-M. J. et al. Erythrocyte membrane-camouflaged polymeric nanoparticles as a biomimetic delivery platform. Proc. Natl Acad. Sci. USA 108, 10980–10985 (2011).

    CAS  Article  Google Scholar 

  12. 12.

    Lodish, H. et al. Molecular Cell Biology (W. H. Freeman, 2007).

  13. 13.

    Zhu, Y., Huang, W., Lee, S. S. K. & Xu, W. Crystal structure of a polyphosphate kinase and its implications for polyphosphate synthesis. EMBO Rep. 6, 681–687 (2005).

    CAS  Article  Google Scholar 

  14. 14.

    Anderson, A. J., Haywood, G. W. & Dawes, E. A. Biosynthesis and composition of bacterial poly(hydroxyalkanoates). Int. J. Biol. Macromol. 12, 102–105 (1990).

    CAS  Article  Google Scholar 

  15. 15.

    Kessler, B. & Witholt, B. Factors involved in the regulatory network of polyhydroxyalkanoate metabolism. J. Biotechnol. 86, 97–104 (2001).

    CAS  Article  Google Scholar 

  16. 16.

    Adams, D. J. Fungal cell wall chitinases and glucanases. Microbiology 150, 2029–2035 (2004).

    CAS  Article  Google Scholar 

  17. 17.

    Arakawa, Y. et al. Genomic organization of the Klebsiella pneumoniae cps region responsible for serotype K2 capsular polysaccharide synthesis in the virulent strain Chedid. J. Bacteriol. 177, 1788–1796 (1995).

    CAS  Article  Google Scholar 

  18. 18.

    Chien, L. J. & Lee, C. K. Enhanced hyaluronic acid production in Bacillus subtilis by coexpressing bacterial hemoglobin. Biotechnol. Prog. 23, 1017–1022 (2007).

    CAS  PubMed  Google Scholar 

  19. 19.

    Brangwynne, C. P., Tompa, P. & von Pappu, R. Polymer physics of intracellular phase transitions. Nat. Phys. 11, 899–904 (2015).

    CAS  Article  Google Scholar 

  20. 20.

    Rehm, B. H. A. Bacterial polymers: biosynthesis, modifications and applications. Nat. Rev. Microbiol. 8, 578–592 (2010).

    CAS  Article  Google Scholar 

  21. 21.

    Yang, S. H. et al. Mussel-inspired encapsulation and functionalization of individual yeast cells. J. Am. Chem. Soc. 133, 2795–2797 (2011).

    CAS  Article  Google Scholar 

  22. 22.

    Tytgat, L. et al. in 3D Printing and Biofabrication (eds Ovsianikov, A., Yoo, J. & Mironov, V.) Vol. 96, 1–43 (Springer International, 2017).

  23. 23.

    Williams, C. G., Malik, A. N., Kim, T. K., Manson, P. N. & Elisseeff, J. H. Variable cytocompatibility of six cell lines with photoinitiators used for polymerizing hydrogels and cell encapsulation. Biomaterials 26, 1211–1218 (2005).

    CAS  Article  Google Scholar 

  24. 24.

    Yang, J. et al. Nanoencapsulation of individual mammalian cells with cytoprotective polymer shell. Biomaterials 133, 253–262 (2017).

    CAS  Article  Google Scholar 

  25. 25.

    Xia, Y. et al. Photopolymerized injectable water-soluble maleilated chitosan/poly(ethylene glycol) diacrylate hydrogels as potential tissue engineering scaffolds. J. Photopolym. Sci. Technol. 30, 33–40 (2017).

    CAS  Article  Google Scholar 

  26. 26.

    Pathak, C. P., Sawhney, A. S. & Hubbell, J. A. Rapid photopolymerization of immunoprotective gels in contact with cells and tissue. J. Am. Chem. Soc. 114, 8311–8312 (1992).

    CAS  Article  Google Scholar 

  27. 27.

    Magennis, E. P. et al. Bacteria-instructed synthesis of polymers for self-selective microbial binding and labelling. Nat. Mater. 13, 748–755 (2014).

    CAS  Article  Google Scholar 

  28. 28.

    Kim, J. Y. et al. Cytocompatible polymer grafting from individual living cells by atom‐transfer radical polymerization. Angew. Chem. Int. Ed. 55, 15306–15309 (2016).

    CAS  Article  Google Scholar 

  29. 29.

    Niu, J. et al. Engineering live cell surfaces with functional polymers via cytocompatible controlled radical polymerization. Nat. Chem. 9, 537–545 (2017).

    CAS  Article  Google Scholar 

  30. 30.

    Ma, X. et al. Construction and potential applications of a functionalized cell with an intracellular mineral scaffold. Angew. Chem. Int. Ed. 50, 7414–7417 (2011).

    CAS  Article  Google Scholar 

  31. 31.

    Sweeney, R. Y. et al. Bacterial biosynthesis of cadmium sulfide nanocrystals. Chem. Biol. 11, 1553–1559 (2004).

    CAS  Article  Google Scholar 

  32. 32.

    Klaus, T., Joerger, R., Olsson, E. & Granqvist, C.-G. Silver-based crystalline nanoparticles, microbially fabricated. Proc. Natl Acad. Sci. USA 96, 13611–13614 (1999).

    CAS  Article  Google Scholar 

  33. 33.

    Said, El,W. A., Cho, H. Y., Yea, C. H. & Choi, J. W. Synthesis of metal nanoparticles inside living human cells based on the intracellular formation process. Adv. Mater. 26, 910–918 (2014).

    Article  Google Scholar 

  34. 34.

    Li, Y. et al. Mechanism-oriented controllability of intracellular quantum dots formation: the role of glutathione metabolic pathway. ACS Nano 7, 2240–2248 (2013).

    CAS  Article  Google Scholar 

  35. 35.

    Cui, R. et al. Living yeast cells as a controllable biosynthesizer for fluorescent quantum dots. Adv. Funct. Mater. 19, 2359–2364 (2009).

    CAS  Article  Google Scholar 

  36. 36.

    Bryant, S. J., Nuttelman, C. R. & Anseth, K. S. Cytocompatibility of UV and visible light photoinitiating systems on cultured NIH/3T3 fibroblasts in vitro. J. Biomater. Sci. Polym. Ed. 11, 439–457 (2000).

    CAS  Article  Google Scholar 

  37. 37.

    Fedorovich, N. E. et al. The effect of photopolymerization on stem cells embedded in hydrogels. Biomaterials 30, 344–353 (2009).

    CAS  Article  Google Scholar 

  38. 38.

    Schweikl, H., Spagnuolo, G. & Schmalz, G. Genetic and cellular toxicology of dental resin monomers. J. Dent. Res. 85, 870–877 (2006).

    CAS  Article  Google Scholar 

  39. 39.

    Issa, Y., Watts, D. C., Brunton, P. A., Waters, C. M. & Duxbury, A. J. Resin composite monomers alter MTT and LDH activity of human gingival fibroblasts in vitro. Dent. Mater. 20, 12–20 (2004).

    CAS  Article  Google Scholar 

  40. 40.

    Vasey, P. A. et al. Phase I clinical and pharmacokinetic study of PK1 [N-(2-hydroxypropyl)methacrylamide copolymer doxorubicin]: first member of a new class of chemotherapeutic agents—drug–polymer conjugates. Clin. Cancer Res. 5, 83–94 (1999).

    CAS  PubMed  Google Scholar 

  41. 41.

    Callahan, J. & Kopeček, J. Semitelechelic HPMA copolymers functionalized with triphenylphosphonium as drug carriers for membrane transduction and mitochondrial localization. Biomacromolecules 7, 2347–2356 (2006).

    CAS  Article  Google Scholar 

  42. 42.

    Kopecek, J. & Kopečková, P. HPMA copolymers: origins, early developments, present and future. Adv. Drug Deliv. Rev. 62, 122–149 (2010).

    CAS  Article  Google Scholar 

  43. 43.

    Lilly, J. L., Romero, G., Xu, W., Shin, H. Y. & Berron, B. J. Characterization of molecular transport in ultrathin hydrogel coatings for cellular immunoprotection. Biomacromolecules 16, 541–549 (2015).

    CAS  Article  Google Scholar 

  44. 44.

    Dröge, W. Free radicals in the physiological control of cell function. Physiol. Rev. 82, 47–95 (2002).

    Article  Google Scholar 

  45. 45.

    Armstrong, D. Advanced Protocols in Oxidative Stress II (Humana, 2010).

  46. 46.

    Ridley, A. J. et al. Cell migration: integrating signals from front to back. Science 302, 1704–1709 (2003).

    CAS  Article  Google Scholar 

  47. 47.

    Hood, J. D. & Cheresh, D. A. Role of integrins in cell invasion and migration. Nat. Rev. Cancer 2, 91–100 (2002).

    Article  Google Scholar 

  48. 48.

    Scharffetter-Kochanek, K. et al. UV-induced reactive oxygen species in photocarcinogenesis and photoaging. J. Biol. Chem. 378, 1247–1257 (1997).

    CAS  Google Scholar 

  49. 49.

    Roca-Cusachs, P., Conte, V. & Trepat, X. Quantifying forces in cell biology. Nat. Cell Biol. 19, 742–751 (2017).

    CAS  Article  Google Scholar 

  50. 50.

    Poirier, M. G. & Marko, J. F. Effect of internal friction on biofilament dynamics. Phys. Rev. Lett. 88, 228103 (2002).

    Article  Google Scholar 

  51. 51.

    Mizuno, D., Tardin, C., Schmidt, C. F. & MacKintosh, F. C. Nonequilibrium mechanics of active cytoskeletal networks. Science 315, 370–373 (2007).

    CAS  Article  Google Scholar 

  52. 52.

    Vasconcellos, C. A. et al. Reduction in viscosity of cystic-fibrosis sputum in-vitro by gelsolin. Science 263, 969–971 (1994).

    CAS  Article  Google Scholar 

  53. 53.

    Nakamura, F., Osborn, E., Janmey, P. A. & Stossel, T. P. Comparison of filamin A-induced cross-linking and Arp2/3 complex-mediated branching on the mechanics of actin filaments. J. Biochem. 277, 9148–9154 (2002).

    CAS  Google Scholar 

  54. 54.

    Blanchoin, L. & Pollard, T. D. Interaction of actin monomers with acanthamoeba actophorin (ADF/cofilin) and profilin. J. Biochem. 273, 25106–25111 (1998).

    CAS  Google Scholar 

  55. 55.

    Püspöki, Z., Storath, M., Sage, D. & Unser, M. Focus on bio-image informatics, in Proc. AAECB Vol. 219, 69–93 (Springer, 2016).

  56. 56.

    Boudaoud, A. et al. FibrilTool, an ImageJ plug-in to quantify fibrillar structures in raw microscopy images. Nat. Protoc. 9, 457–463 (2014).

    CAS  Article  Google Scholar 

  57. 57.

    Wang, Z. et al. Long-term fluorescent cellular tracing by the aggregates of AIE bioconjugates. J. Am. Chem. Soc. 135, 8238–8245 (2013).

    CAS  Article  Google Scholar 

  58. 58.

    Major, M. D. & Torkelson, J. M. Fluorescence of vinyl aromatic polyelectrolytes: effects of conformation, concentration, and molecular weight of sodium poly (styrene sulfonate). Macromolecules 1986, 2806–2810 (1986).

    Google Scholar 

  59. 59.

    Ander, P. & Mahmoudhagh, M. K. Excimer formation of poly (styrenesulfonic acid) and its salts in solution. Macromolecules 15, 214–216 (1982).

    Article  Google Scholar 

  60. 60.

    Yan, J. J. et al. Polymerizing nonfluorescent monomers without incorporating any fluorescent agent produces strong fluorescent polymers. Adv. Mater. 24, 5617–5624 (2012).

    CAS  Article  Google Scholar 

  61. 61.

    Gerweck, L. E. & Seetharaman, K. Cellular pH gradient in tumor versus normal tissue: potential exploitation for the treatment of cancer. Cancer Res. 56, 1194–1198 (1996).

    CAS  PubMed  Google Scholar 

  62. 62.

    Johnson, D. E., Ostrowski, P., Jaumouillé, V. & Grinstein, S. The position of lysosomes within the cell determines their luminal pH. J. Cell Biol. 212, 677–692 (2016).

    CAS  Article  Google Scholar 

  63. 63.

    Bridges, J. W. & Williams, R. T. The fluorescence of indoles and aniline derivatives. Biochem. J. 107, 225–237 (1968).

    CAS  Article  Google Scholar 

  64. 64.

    Goswami, T. K. et al. Ferrocene-conjugated copper(ii) complexes of l-methionine and phenanthroline bases: synthesis, structure and photocytotoxic activity. Organometallics 31, 3010–3021 (2012).

    CAS  Article  Google Scholar 

  65. 65.

    Chen, S., Lu, J., Sun, C. & Ma, H. A highly specific ferrocene-based fluorescent probe for hypochlorous acid and its application to cell imaging. Analyst 135, 577–582 (2010).

    CAS  Article  Google Scholar 

  66. 66.

    Kumar, K., Vulugundam, G., Kondaiah, P. & Bhattacharya, S. Co-liposomes of redox-active alkyl-ferrocene modified low MW branched PEI and DOPE for efficacious gene delivery in serum. J. Mater. Chem. B 3, 2318–2330 (2015).

    CAS  Article  Google Scholar 

  67. 67.

    Vankayala, R., Kalluru, P., Tsai, H.-H., Chiang, C.-S. & Hwang, K. C. Effects of surface functionality of carbon nanomaterials on short-term cytotoxicity and embryonic development in zebrafish. J. Mater. Chem. B 2, 1038–1047 (2014).

    CAS  Article  Google Scholar 

  68. 68.

    Blanazs, A., Ryan, A. J. & Armes, S. P. Predictive phase diagrams for RAFT aqueous dispersion polymerization: effect of block copolymer composition, molecular weight and copolymer concentration. Macromolecules 45, 5099–5107 (2012).

    CAS  Article  Google Scholar 

  69. 69.

    Refojo, M. F. Hydrophobic interaction in poly(2-hydroxyethyl methacrylate) homogeneous hydrogel. J. Polym. Sci. A 5, 3103–3113 (1967).

    Google Scholar 

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This work was supported by the European Research Council (advanced grant ADREEM ERC-2013-340469) and the Rosetrees Trust (A865). N.T. acknowledges support from the Commonwealth Scholarship Commission and W.L. from the Chinese Scholarship Council. The authors thank the Wellcome Trust for Multi-user Equipment Grant WT104915MA.

Author information




J.G. and M.B. conceived, designed and directed the project. W.L. and Y.Z. conducted the control polymerizations and MTT assays. Y.Z. performed the actin experiments, Y.Z. and N.T. conducted the wound healing experiments. W.L., Y.Z. and J.C. carried out work with the fluorescent polymers. J.G., A.L. and M.B. co-wrote the manuscript. All authors analysed the data and contributed to the scientific discussion and revised the manuscript.

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Correspondence to Mark Bradley.

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Polymerized sodium 4-styrenesulfonate inside cells

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Geng, J., Li, W., Zhang, Y. et al. Radical polymerization inside living cells. Nat. Chem. 11, 578–586 (2019). https://doi.org/10.1038/s41557-019-0240-y

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