Research ArticleAPPLIED SCIENCES AND ENGINEERING

Flexible elastomer patch with vertical silicon nanoneedles for intracellular and intratissue nanoinjection of biomolecules

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Science Advances  09 Nov 2018:
Vol. 4, no. 11, eaau6972
DOI: 10.1126/sciadv.aau6972
  • Fig. 1 Images and illustrations for the integration of vertically ordered Si NNs onto an elastomer patch.

    (A) A series of scanning electron microscopy (SEM) images of vertically ordered Si pillars with selected passivation layer (left), with localized undercut (middle), and after the size is reduced down to the nanoscale (right). Scale bar, 1 μm. (B) Schematic illustrations of the key steps to physically liberate Si NNs from their native Si wafer via the swelling of PDMS. (C) Optical image of a representative Si NN-patch. Scale bar, 1.5 cm. (D) Magnified SEM image of the partly embedded Si NNs into PDMS. The inset highlights the needle-like sharp tips. Scale bars, 20 μm and 600 nm (inset). (E) Confocal laser scanning microscopy (CLSM) image of Si NNs. Scale bar, 30 μm.

  • Fig. 2 Mechanism study and mechanical analysis for controlled cracking of Si NNs.

    (A) FEA results of displacement of PDMS under swelling at 100, 170, and 230%. (B) Corresponding FEA results of maximum principal strain distributions along a single Si NN during each swelling condition. (C) Computational data showing the effect of peak strain (εpeak) on S (left), D/d ratio (middle), and H/h ratio (right). Black dashed line denotes a theoretical fracture limit of the Si NN.

  • Fig. 3 Basic characterizations of Si NN-patch.

    (A) Results of MTT assay in the cytotoxicity tests of HDF cells interfaced with the Si NN-patch (green) and control Si NNs on a Si wafer (red) and a bare Si wafer (yellow). Error bar represents the SD of three replicates. (B) Results of LDH assay in the invasiveness tests of HDF cells for 2 days. Triton X-100 is used as a positive control (blue). Error bar represents the SD of three replicates. (C) SEM images of MCF7 cells on a representative Si NN-patch at 24 hours after nanoinjection. Scale bar, 10 μm. Arrows highlight the deformed Si NNs by cell deformations. (D) Time-lapsed live differential interference contrast (DIC) images of HDF cells that interacted with Si NNs at the bottom. Scale bar, 10 μm.

  • Fig. 4 Formation of nanoscale surface pores and intracellular nanoinjection of siRNA.

    (A) SEM images of nanopores formed on the surface of Si NNs at different treatment times of MACE. Scale bar, 250 nm. (B) Confocal microscopy images of Si NNs with (left) and without (right) nanopores on the surface by using a green fluorescence dye. Scale bar, 15 μm. (C) Confocal microscopy image of nanoporous Si NNs loaded with Cy3-siRNAs (red). Scale bar, 15 μm. (D) Confocal microscopy image of GFP-MCF7 cells at 24 hours after nanoinjection of Cy3-siRNAs. Scale bar, 15 μm. (E) Results of flow cytometry (FACS) analysis for SKOV3 cells at 48 hours after nanoinjection of Cy3-siRNAs by using the nanoporous Si NN-patch (green) and control Si NNs on a bulk Si wafer with (red) and without (blue) nanopores on the surface and a bare Si wafer (yellow). (F) Corresponding results of GAPDH analysis for the SKOV3 cells. Error bar represents the SD of three replicates.

  • Fig. 5 Intratissue nanoinjection of Si NN-patch.

    (A) Optical images of the mice interfaced with the Si NN-patch for intradermal (left) and intramuscular (middle) nanoinjection. Scale bar, 1 cm. Conventional Si NNs built on a bulk Si wafer are used for control comparison (right). (B) Corresponding IVIS images of the mice for up to 48 hours after nanoinjection. Scale bar, 2 cm.

  • Fig. 6 In vivo tissue compatibility of Si NN-patch.

    (A) Real-time bioluminescence images on the skin, muscle, and ear of the mice at 5 hours following the implementation of the Si NN-patch (left column) and control Si NNs (middle column) and with control PMA treatment (right column). Scale bar, 10 mm. (B) Corresponding H&E histological cross-sectional views of the treated tissue sections. Scale bar, 400 μm.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/11/eaau6972/DC1

    Fig. S1. SEM images (scale bar, 10 μm) of the donor Si wafer and the receiver PDMS substrate after the physical separation process, with their enlarged images (scale bar, 1 μm).

    Fig. S2. SEM images of Si NNs with varied tip size and height.

    Fig. S3. Schematic illustration for modeling geometry and boundary conditions and computational results (FEA) of strain distributions of a single Si NN under deformations at varied D/d ratio, h, and S.

    Fig. S4. Computational (FEA) data showing the effect of peak strain (εpeak) on D/d ratio and H/h ratio using dichloromethane (green), hexane (red), and ethanol (blue).

    Fig. S5. SEM images (scale bars, 7, 5, and 3 μm from the top) of cells interfaced with control Si NNs built on a bulk Si wafer.

    Fig. S6. SEM images (scale bars, 7 and 10 μm from the left) of SKOV3 cells (left) and HDF cells (right) interfaced with different sizes of Si NNs at the bottom.

    Fig. S7. SEM images (scale bars, 5 and 1.5 μm from the left) of control Si NNs without the nanoscale pores on the surface.

    Fig. S8. Confocal microscopy images (scale bar, 10 μm) of the cultured MCF7 cells at 30 min after nanoinjection by either pressing Si NNs on top (left) or seeding the cells on Si NNs (right).

    Fig. S9. Measured GAPDH expression by a control nanoinjection of scrambled siRNAs (left) and a control treatment in the siRNA solution (right).

    Fig. S10. Dissolved diameter (D/D0 ratio) of nanoporous Si NNs in a PBS solution with pH values of 7.4 (red) and 10 (blue) at 37.5°C.

    Movie S1. An experimental demonstration (scale bar, 2.5 mm; 20× speed) showing the expansion of PDMS when soaked in hexane.

    Movie S2. FEA results of displacement for a simplified structure that includes an array (3 cm × 3 cm) of Si NNs on a thin layer of PDMS under the expansion up to 230% in volume.

    Movie S3. Continuously recorded live DIC image (scale bar, 15 μm; 4000× speed) of MCF7 cells for 36 hours.

    Movie S4. A continuously recorded movie (scale bar, 2 cm; 1× speed) showing a mouse awake with the attached Si NN-patch on the skin.

    Movie S5. A continuously recorded movie (scale bar, 2 cm; 1× speed) showing a mouse awake with the implanted Si NN-patch on the subcutaneous muscle.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. SEM images (scale bar, 10 μm) of the donor Si wafer and the receiver PDMS substrate after the physical separation process, with their enlarged images (scale bar, 1 μm).
    • Fig. S2. SEM images of Si NNs with varied tip size and height.
    • Fig. S3. Schematic illustration for modeling geometry and boundary conditions and computational results (FEA) of strain distributions of a single Si NN under deformations at varied D/d ratio, h, and S.
    • Fig. S4. Computational (FEA) data showing the effect of peak strain (εpeak) on D/d ratio and H/h ratio using dichloromethane (green), hexane (red), and ethanol (blue).
    • Fig. S5. SEM images (scale bars, 7, 5, and 3 μm from the top) of cells interfaced with control Si NNs built on a bulk Si wafer.
    • Fig. S6. SEM images (scale bars, 7 and 10 μm from the left) of SKOV3 cells (left) and HDF cells (right) interfaced with different sizes of Si NNs at the bottom.
    • Fig. S7. SEM images (scale bars, 5 and 1.5 μm from the left) of control Si NNs without the nanoscale pores on the surface.
    • Fig. S8. Confocal microscopy images (scale bar, 10 μm) of the cultured MCF7 cells at 30 min after nanoinjection by either pressing Si NNs on top (left) or seeding the cells on Si NNs (right).
    • Fig. S9. Measured GAPDH expression by a control nanoinjection of scrambled siRNAs (left) and a control treatment in the siRNA solution (right).
    • Fig. S10. Dissolved diameter (D/D0 ratio) of nanoporous Si NNs in a PBS solution with pH values of 7.4 (red) and 10 (blue) at 37.5°C.
    • Legends for Movies S1 to S5

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.avi format). An experimental demonstration (scale bar, 2.5 mm; 20× speed) showing the expansion of PDMS when soaked in hexane.
    • Movie S2 (.avi format). FEA results of displacement for a simplified structure that includes an array (3 cm × 3 cm) of Si NNs on a thin layer of PDMS under the expansion up to 230% in volume.
    • Movie S3 (.avi format). Continuously recorded live DIC image (scale bar, 15 μm; 4000× speed) of MCF7 cells for 36 hours.
    • Movie S4 (.avi format). A continuously recorded movie (scale bar, 2 cm; 1× speed) showing a mouse awake with the attached Si NN-patch on the skin.
    • Movie S5 (.avi format). A continuously recorded movie (scale bar, 2 cm; 1× speed) showing a mouse awake with the implanted Si NN-patch on the subcutaneous muscle.

    Files in this Data Supplement:

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