Research ArticleAPPLIED SCIENCES AND ENGINEERING

Conformable self-assembling amyloid protein coatings with genetically programmable functionality

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Science Advances  20 May 2020:
Vol. 6, no. 21, eaba1425
DOI: 10.1126/sciadv.aba1425
  • Fig. 1 E. coli biofilm-inspired protein nanofiber coatings and corresponding proof-of-concept applications including electronic devices, enzyme immobilization, and microfluidic sensor.

    (A) Illustration of natural E. coli biofilms, in which self-assembled CsgA nanofibers constitute the major protein component. (B) Modular genetic design of genetically engineered CsgA proteins enabled by rationally fusing desired fusion domains at the C terminus of CsgA. (C) Illustrations of producing diverse protein coatings via a solution-based fabrication approach for various applications based on genetically engineered functionalities such as electronic devices, enzyme immobilization, and microfluidic sensor (from top to bottom).

  • Fig. 2 Characterization, environmental tolerance, and substrate universality of CsgAHis-tag protein coatings.

    (A) Top: Digital images and water contact angles (inset) of bare and CsgAHis-tag–coated PTFE; bottom: digital images of bare and coated PTFE substrates after incubation with QD solution and illumination under UV light. Photo credit: Yingfeng Li, ShanghaiTech University. (B) AFM height image of CsgAHis-tag–coated PTFE. (C) XPS spectra of bare and CsgAHis-tag–coated PTFE, CPS representing counts per second. (D) Schematic showing stability tests consisting of a water contact angle test and a QD binding test. (E) Water contact angle comparison of CsgAHis-tag coatings on PTFE substrates after organic solvent exposure. (F) Digital image of challenged CsgAHis-tag–coated PTFE substrates after incubation with QD solution and illumination under UV light. Photo credit: Yingfeng Li, ShanghaiTech University. (G) Water contact angles of bare and CsgAHis-tag–coated diverse polymer substrates. (H) Water contact angles of bare and CsgAHis-tag–coated various inorganic substrates.

  • Fig. 3 Construction and characterization of CsgAHis-tag–Au conductive coatings and electronic devices.

    (A) Schematic showing the fabrication of Au coatings based on CsgAHis-tag coatings. (B) Digital images of pristine and Au-coated CsgAHis-tag–modified 3D printed pyramids. Photo credit: Yingfeng Li, ShanghaiTech University. (C) Digital (left) and SEM (right) images of an Au interdigital electrode fabricated by a CsgAHis-tag coating–enabled gold enhancement process assisted by a patterned waterproof sticker. Photo credit: Yingfeng Li, ShanghaiTech University. (D) XPS spectrum of the Au interdigital electrode. (E) Capacitance change of the Au interdigital electrode with different distances between the electrode and a finger; the inset digital images indicate different distances. Photo credit: Yingfeng Li, ShanghaiTech University. (F) Digital images of the Au interdigital electrode as the sensing element in a touch switch. Photo credit: Yingfeng Li, ShanghaiTech University. (G) Digital (left) and SEM (right) images of pristine (top) and Au-coated textiles (bottom). Photo credit: Yingfeng Li, ShanghaiTech University. (H) Schematic diagram of a pressure sensor fabricated by Au-coated textiles along with an Au interdigital electrode (inset) and the corresponding current variation (∆I/I0) under different pressures. (I) Current variation as a function of time at two pressures (the inset digital images indicate the two different types of pressure applied). Photo credit: Yingfeng Li, ShanghaiTech University.

  • Fig. 4 Programmable amyloid coatings for tunable fluorescent materials and enzymatic bioconversion systems.

    (A) Illustration of CsgASpyTag/CsgASnoopTag (1:1, weight ratio)–coated microparticles. (B) SEM images of a CsgASpyTag/CsgASnoopTag-coated SiO2 microparticle. (C) Schematic showing fluorescent proteins conjugated on CsgASpyTag/CsgASnoopTag nanofiber (top) and fluorescence microscopy images of corresponding fluorescent protein–conjugated CsgASpyTag/CsgASnoopTag-coated microparticles. (D) Schematic showing the immobilization of LDHSpyCatcher and GOXSnoopCatcher on a CsgASpyTag/CsgASnoopTag-coated microparticle. (E) Illustration of a dual-enzyme reaction system enabled by LDHSpyCatcher and GOXSnoopCatcher co-conjugated microparticles. (F) Conversion ratio of l-tert-leucine in two different microparticle systems (LDHSpyCatcher and GOXSnoopCatcher co-conjugated together on CsgASpyTag/CsgASnoopTag coatings versus LDHSpyCatcher-conjugated CsgASpyTag coatings along with GOXSnoopCatcher-conjugated CsgASnoopTag coatings) during a 3-hour reaction period. (G) Conversion ratio of l-tert-leucine in the CsgASpyTag/CsgASnoopTag coating system over five cycles of 3-hour reactions.

  • Fig. 5 Functional CsgADBD coating–enabled microfluidic bacterial sensors.

    (A) Schematic diagram of a DNAzyme-bound CsgADBD-coated microfluidic sensor device and an illustration of the DNAzyme detection mechanism. (B) Digital image of the microfluidic device. Photo credit: Yingfeng Li, ShanghaiTech University. (C) Fluorescence intensity of RFD-functionalized CsgADBD- and CsgAHis-tag–coated interiors of microfluidic channels upon exposure to supernatants from E. coli cultures of various cell densities. (D) 3D image of the RFD-functionalized CsgADBD coatings activated by E. coli culture (OD600 = 1) supernatants on the microfluidic channel.

Supplementary Materials

  • Supplementary Materials

    Conformable self-assembling amyloid protein coatings with genetically programmable functionality

    Yingfeng Li, Ke Li, Xinyu Wang, Mengkui Cui, Peng Ge, Junhu Zhang, Feng Qiu, Chao Zhong

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