Research ArticleMATERIALS SCIENCE

A novel ternary heterostructure with dramatic SERS activity for evaluation of PD-L1 expression at the single-cell level

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Science Advances  02 Nov 2018:
Vol. 4, no. 11, eaau3494
DOI: 10.1126/sciadv.aau3494
  • Fig. 1 The design and illustration of MGT.

    Schematic illustration of the synthesis process and enhancement mechanism of the MGT substrate.

  • Fig. 2 Characterization of MGT nanocomposites.

    (A) SEM image of the MG substrate. (B) TEM image of the MG substrate. Inset: Size distribution of MG by dynamic light scattering measurement. a.u., arbitrary units. (C) SEM image of MGT nanocomposites. (D) TEM image of MGT nanocomposites. Inset: Size distribution of MGT by dynamic light scattering measurement. (E) N2 sorption isotherms and (F) corresponding pore size distribution curves of the MGT. (G) (I) Bright-field EDS images, (II) high-magnification image of (I) (marked with a green square), (III) high-resolution image of a select region in (II) (marked with a red square), and (IV to VIII) low-/high-magnification EDS images of MGT. (H) XRD patterns of (I) Fe3O4 NPs, (II) MG, (III) MGT, and (IV to VI) standard patterns of (IV) Fe3O4, (V) GO, and (VI) porous TiO2 NPs. (I) Raman spectra and (J) FTIR spectra of (I) Fe3O4 NPs, (II) GO, (III) MG, (IV) Fe3O4@TiO2 (MT), and (V) MGT. (K) The magnetic hysteresis loops at 300 K of the MGT. Inset: Photograph of the magnetic separation process of the MGT from the solution. emu, electromagnetic units.

  • Fig. 3 Enhancement effect of MGT.

    Raman spectra of (A) CC, (B) PTCDA, (C) CV, and (D) CuPc on (I) Fe3O4 NPs (M), (II) MT, (III) MG, and (IV) MGT substrates under excitation of a 633-nm laser.

  • Fig. 4 Raman enhancement mechanism of MGT.

    (A) XPS survey spectra of MG and MGT nanocomposites. High-resolution XPS spectra of (B) C 1s, (C) O 1s, and (D) Ti 3p of MG and MGT nanocomposites. TDR spectroscopic measurement for (E) MG, (F) MGT, and (G) CuPc after irradiation with a 633-nm laser flash. OD, optical density. (H) Time profiles of normalized transient absorption at 750 nm. (I) Two-dimensional integrated density difference plotted along the slab’s perpendicular axis. The bottom dashed line at 16 indicates the position of graphene, and the upper dashed line at 28 denotes that of the molecule. The red line indicates the charge difference on the GO and the green line denotes that on the TiO2-supported GO. (J) Conclusion of calculated results and the mechanism in MGT platforms. (K) Raman spectra of CuPc on Fe3O4, TiO2 (T), MT, MG, MGT with compact TiO2 shell (cMGT), Fe3O4@TiO2@GO (MTG), and MGT with the porous TiO2 shell (MGT) substrates under a 633-nm laser (5 mW) with an exposure time of 0.5 s.

  • Fig. 5 Evaluation of PD-L1 expression on cell face.

    (A) Site-specific recognition and detection of PD-L1 on TNBC cells. (B) Raman spectra of MGT-Abs-CuPc obtained with HCC38 cells at various concentrations. (C) Plot of Raman scattering intensity versus logarithm of cell numbers. Each data point represents the average value from six replicate SERS spectra (SD, n = 6). Error bars represent SDs. (D) Plot of I versus the effect of PD-L1 concentration (m) on the decrease of Raman intensity at 1530 cm−1I) of HCC38 cells on the cytosensor. (E) Raman spectra of MGT-Abs-CuPc obtained with MDA-MB-231 cells at various concentrations. (F) Plot of Raman scattering intensity versus logarithm of cell numbers. Each data point represents the average value from six replicate SERS spectra (SD, n = 6). Error bars represent SDs. (G) Effect of PD-L1 concentration (m) on the decrease of Raman intensity at 1530 cm−1I) of MDA-MB-231 cells on the cytosensor. (H) Raman spectra of MGT-Abs-CuPc obtained with MCF-7 cells at various concentrations. (I) Plot of Raman scattering intensity versus logarithm of cell numbers. Each data point represents the average value from six replicate SERS spectra (SD, n = 6). Error bars represent SDs. (J) Effect of PD-L1 concentration (m) on the decrease of Raman intensity at 1530 cm−1I) of MCF-7 cells on the cytosensor. (K) The expression of PD-L1 on the cell surface. (L) Raman scanning mapping images obtained from HCC38, MDA-MB-231, and MCF-7 incubated with 0, 4, 10, 16, and 20 ng of IFN-γ for 48 hours. (M) Raman intensity of the peak at 1530 cm−1 obtained from HCC38, MDA-MB-231, and MCF-7 without stimulation. (N to P) Relationship between the Raman intensity and IFN-γ concentration for (N) HCC38, (O) MDA-MB-231, and (P) MCF-7 cells.

  • Table 1 EF value of CuPc on M, T, MT, MG, cMGT, MTG, and MGT substrates.
    SubstrateMTMTMGcMGTMTGMGT
    EF value3.05 × 1054.67 × 1051.06 × 1068.08 × 106

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/11/eaau3494/DC1

    Fig. S1. Characterization of nanostructures.

    Fig. S2. Recyclability of MGT.

    Fig. S3. Photostability of CuPc of MGT nanocomposites.

    Fig. S4. Mechanism of Raman enhancement of MGT.

    Fig. S5. Characterization and experimental optimization of MGT-Abs-CuPc.

    Fig. S6. Cytotoxicity of the MGT-Abs-CuPc probe.

    Fig. S7. Kinetics mechanism of antigen-Abs reaction and ELISA data of PD-L1 expression.

    Fig. S8. Raman scanning mapping images of three different types of breast cancer cells incubated at various times.

    Fig. S9. Calculation of EF values of MGT.

    Table S1. Selected vibrational modes of CuPc.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Characterization of nanostructures.
    • Fig. S2. Recyclability of MGT.
    • Fig. S3. Photostability of CuPc of MGT nanocomposites.
    • Fig. S4. Mechanism of Raman enhancement of MGT.
    • Fig. S5. Characterization and experimental optimization of MGT-Abs-CuPc.
    • Fig. S6. Cytotoxicity of the MGT-Abs-CuPc probe.
    • Fig. S7. Kinetics mechanism of antigen-Abs reaction and ELISA data of PD-L1 expression.
    • Fig. S8. Raman scanning mapping images of three different types of breast cancer cells incubated at various times.
    • Fig. S9. Calculation of EF values of MGT.
    • Table S1. Selected vibrational modes of CuPc.

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