HTML
-
Solvent dye was first dissolved in the PDMS prepolymer (Sylgard 184, Dow Corning, USA) and methyl phenyl polymer (Andisil, AB Specialty Silicones, USA). Sudan Ⅳ (Aladdin, China), Sudan Ⅱ (Aladdin, China), Solvent green 28 (J & I Biological, China), and Solvent blue 59 (Sigma-Aldrich, Germany) were used as red, yellow, green, and blue solvent dyes, respectively. The mixture ratios of the red, yellow, green, and blue solvent in the PDMS prepolymer and the methyl phenyl polymer were 0.42 and 0.45 μg mL-1, respectively. PDMS cross-linker was then mixed with the PDMS prepolymer at a weight ratio of 1:5 (the ratio between the cross-linker and the prepolymer). A thin PDMS film was applied on the round protruding camera housing (Model Ⅰ) and cured for 30 min at room temperature. A lens was then directly formed by dripping the liquid-state PDMS and the polymer on the camera housing. To prevent the PDMS from dropping off the edge of the camera housing and to realize a short focal length, the contact angle, θPDMS, must obey the condition θPDMS < θC. To ensure that this condition is met, the contact angle can be set as the supplementary angle to the subtended angle at the edge, i.e., θPDMS = 180°-φ. Using this assumption, the total volume of the PDMS and the polymer that will prevent overflow could then be determined as
$$ V_{\rm{Total}} = \frac{{\pi D_{\rm{PDMS}}^3}}{{24\left( {\sin \theta _{\rm{PDMS}}} \right)^3}}\left( {2 + \cos \theta _{\rm{PDMS}}} \right)\left( {1 - \cos \theta _{\rm{PDMS}}} \right)^2 $$ (1) where DPDMS is the diameter of the round protruding camera housing or the disk (Fig. S2 in the Supplementary Information). In addition, the base diameter of the polymer droplet, DOil, should be equal to or slightly larger than the aperture of the camera lens. The PDMS was solidified after curing for 8 h at room temperature. The lens formed directly on the camera housing could be easily peeled off for later use or replacement with another preprepared lens. A thin PDMS layer applied to the camera housing, which could be cured after 30 min at room temperature, was used to adhere the spare lens.
If the camera housing was of the other forms (Model Ⅱ), the lens was fabricated on a glass disk whose diameter fitted the camera housing. A PDMS film was coated onto the glass disk and solidified at 80 ℃ for 3 min. The PDMS and the polymer were dripped onto the glass disk, successively. The PDMS was solidified after 1 h at 80 ℃. Meanwhile, a thin PDMS layer was applied over the camera housing. Finally, the lens was transferred onto the camera housing and could be used after 30 min at room temperature. The lens on the camera housing could be replaced with the spare lens following the procedure in Model Ⅰ. The models of the smartphones used in the experiments are iPhone 6s Plus and Nokia 7 representing the Model Ⅰ and Model Ⅱ camera housings, respectively. For bioanalytical microscopic imaging, the lenses fabricated for the iPhone 6s Plus and Nokia 7 have focal lengths of 4.6 and 5 mm, respectively.
-
Optical spectra of the cured PDMS and polymer solution with and without solvent dye were measured using a spectrophotometer (LAMBDA 1050, PerkinElmer, USA). ODs ranging from 300 to 800 nm were observed, as shown in Fig. S7 in the Supplementary Information. The PDMS and polymer without solvent dye are transparent within the visible spectrum. The PDMS and polymer dyed with the blue solvent dye serve as a bandpass filter with a peak wavelength of ~440 nm and a -10 dB bandwidth of 50 nm and as a longpass filter with a cut-on wavelength of 680 nm. There is a transmission band centred at 550 nm with a -10 dB bandwidth of 45 nm in the PDMS and polymer dyed with the green solvent dye. If the PDMS and polymer are dyed with the yellow solvent dye and the red solvent dye, they function as longpass filters with cut-on wavelengths of 562 and 594 nm, respectively.
-
The focal length of the lens was calculated based on the profile of the PDMS cap and the polymer droplet and verified by experimental measurement. In the theoretical analysis, the PDMS spherical cap can be described as $y_{\mathrm{PDMS}} = \sqrt {\left({D_{\mathrm{PDMS}}/2\sin \left({\theta _{\mathrm{PDMS}}} \right)} \right)^2 - x^2} - D_{\mathrm{PDMS}}/2\sin \left({\theta _{\mathrm{PDMS}}} \right) + h_{\mathrm{PDMS}}$, and the curvature radius of the spherical cap can be expressed as $R_{\mathrm{PDMS}} = D_{\mathrm{PDMS}}/\left({2\sin \left({\theta _{\mathrm{PDMS}}} \right)} \right)$, while the polymer droplet is elliptical in shape and the upper surface can be written as $y_{\mathrm{Polymer}} = b\sqrt {1 - x^2/a^2} - b + h_{\mathrm{Polymer}}$, which can be approximated by a quartic polynomial $y_{\mathrm{Polymer}\_\mathrm{Approx}} = - bx^4/8a^4 - bx^2/2a^2 + h_{\mathrm{Polymer}}$ using a Taylor series expansion, where hPolymer is the height of the polymer droplet and a and b are the semi-major and semi-minor axes of the ellipse. The profile of the PDMS cap and the polymer droplet were measured by an optical contact angle meter (SL200B, Kino, USA). Then, the focal length of the lens was obtained using Zemax OpticStudio. In addition, the focal length was also quantified during optical imaging. A checkerboard pattern used as an object was illuminated by an LED light source, and an image of the pattern was formed behind the lens. The distances from the object and the image in focus to the lens are denoted u and v, respectively (see Fig. S3 in the Supplementary Information). The primary and secondary principal planes of the lens are located at p1 and p2. A ray perpendicularly passing through the primary principal plane is refracted at the secondary principal plane. The image distance varies with a change in the object distance. During experimentation, the focal length of the lens can be determined using the paraxial approximation. A group of image distances can first be measured by adjusting the object distances. The focal length and the location of the principal planes can then be calculated based on the following relationship
$$ \frac{1}{f} = \frac{1}{{u - p_1}} + \frac{1}{{v - p_2}} $$ (2) -
An illumination source was developed as shown in Fig. S8 in the Supplementary Information. The size of the source is 100 mm × 88 mm × 55 mm (length × width × height). The sample could be placed on top of the source and illuminated through a 25 mm pupil. A white LED was used for bright-field imaging, and 365, 480, and 520 nm LDs used as excitation light sources for fluorescence imaging were mounted on different chips. Once the LED chip or the LD chip was inserted into the illumination source, the chip was positioned by two tiny magnets and connected to the electrodes, thus turning on the LED or the LD automatically. The source was powered by a 12 V battery. The white LED chip was fixed at left of centre with a tilt angle of 10°, generating oblique illumination. The collimated laser beam illuminated the samples with an incident angle of 45°, which was larger than the acceptance angle of the compound lens. Thus, the excitation light would not be directly coupled into the image sensor, efficiently reducing the background noise during fluorescence imaging.
-
The B16-F0 mouse melanoma cell line, HBEC3-KT human bronchial epithelial cell line, 4T1 mouse breast cancer cell line, 293T human embryonic kidney cell line, A375 human malignant melanoma cell line and B×PC-3 human pancreatic cancer cell line from American Type Culture Collection (ATCC, Manassas, VA, USA), and Huh7 human liver cancer cell line from Riken Bioresource Center, Japan, were cultured in Dulbecco's modified Eagle medium (DMEM) culture medium supplemented with 10% foetal bovine serum (FBS), 100 U mL-1 penicillin and 100 μg mL-1 streptomycin. The cells were grown in a 5% carbon dioxide (CO2) humidified incubator at 37 ℃ until 70-80% confluence.
-
The research study was endorsed by the Ethics Committee of Shanghai Cancer Center, Fudan University (Certificate No. 050432-4-1212B) and the Institutional Animal Care and Use Committee of Shanghai Medical College, Fudan University (Certificate No. 20130227-017). Human liver tissues were sourced from Shanghai Cancer Center, Fudan University. In the tumour transplantation experiment, three nude mice purchased from the Chinese Academy of Science were subcutaneously injected with a suspension of B×PC-3 cells, and after 2 weeks, the tumour tissues were collected from the mice under carbon dioxide euthanasia. The tissues were routinely embedded in paraffin and cut into 3 μm sections. The sections of the human tissue samples were incubated with rabbit anti-human CK18 polyclonal antibody (ThermoFisher Scientific), and the sections of the mouse tissue samples were incubated with rabbit anti-human GAPDH polyclonal antibody (ThermoFisher Scientific) overnight at 4 ℃. Then, the sections were incubated with goat anti-rabbit AF488 secondary antibody (ThermoFisher Scientific) for 1 h and DAPI (ThermoFisher Scientific) for 15 min. Finally, the sections were sealed with antifade mountant (ThermoFisher Scientific).
-
A total of 500 ng of pEGFP-C2-NLRP3 plasmids (Addgene) were mixed with Lipofectamine 3000 transfection reagent (ThermoFisher Scientific), and the mixture was incubated for 15 min at room temperature to form a complex. Then, the complex was added to 2 × 105 293T cells. The transfected cells were maintained in DMEM with 10% FBS at 37 ℃ and 5% CO2 for 48 h. Transfection efficiency was determined as the number of 293T cells that expressed EGFP transgene in a total population, which was counted based on DAPI nuclear staining.
-
HBEC3-KT cells were treated with LPS at 50, 100, or 150 μg mL-1 for 24 h. MitoSox Red (5 μM) and DAPI (5 μM) were added to the cells. After 15 min of incubation at 37 ℃, the cells were detected by the HSFM.