Dxr3xi raman imaging microscope

The fibers and as-received GO were monitored with a DXR3xi Raman imaging microscope (Thermo Fisher Scientific, Waltham, MA, USA). Raman spectroscopy was conducted with the laser source at 532 nm, where GO and PVA-GO samples were studied at the laser power of 3 mW and 5 mW, respectively. Core–shell fibers were studied at 6 mW, and all spectra were collected in the range of 200–3200 cm⁻¹. The FTIR spectra of PVA-based fiber mats were measured using a Bruker ALPHA II spectrometer (Ettlingen, Germany) in attenuated total reflectance mode with a diamond crystal placed inside a nitrogen-filled glovebox. The spectra were collected in the range of 400–4000 cm⁻¹.

The samples of the as-received electrospun mats and their components were studied to monitor the peaks attributed to the components and specific ‘fingerprints’ with DXR3xi Raman imaging microscope (Thermo Fisher Scientific, Waltham, MA, USA). Raman spectroscopy was conducted with the laser source 532 nm, where GO and PVA–GO samples were studied at the laser power of 3 mW and 5 mW, respectively. PVA–PEG–SiO₂ and freeze-dried NPs of SiO₂ solution were studied at 6 mW and 4.2 mW of laser power, respectively. Raman spectra of samples were captured in the range of 200–3200 cm^–1.
The PVA–GO composites and the crosslinked fiber films of PVA–PEG–SiO₂@PVA–GO were placed in 0.01 M of the PBS with pH 7.4, at 25 °C for 24 h in the orbital mixer. After 24 h of stirring, the supernatants of solutions were placed in a 96-well plate (Corning 96-well Clear Flat Bottom UV-Transparent Microplate), and fluorescence spectra were recorded with an Infinite M Nano+ (Tecan Trading AG, Männedorf, Switzerland) dual-mode microplate reader. The fluorescence from the samples was excited at 330 nm, and their emission was observed in the range of 350−800 nm.

The surface morphology was examined using a scanning electron microscope (Hitachi S-7400,Tokyo, Japan) outfitted with an EDS analysis instrument. The phase and crystallinity were identified using a Rigaku X-ray diffractometer C (XRD, Rigaku, Japan) with Cu Kα (λ = 1.540 Å) radiation throughout a Bragg angle range of 10° to 80°. Transmission electron microscope (TEM, JEOL JEM-2010, Akishima-Shi, Japan) pictures with standard and high resolution were reported. The Batch mode of Shimadzu’s GC-2025 capillary gas chromatograph was used for gas detection. A special syringe was used to inject the gas into the instrument. The Raman spectrum has been plotted using DXR3xi Raman Imaging Microscope, Thermo Fisher Scientific, USA. X-ray photoelectron spectroscopy analysis (XPS, AXIS-NOVA, Kratos Analytical Ltd., Manchester, UK) was utilized to check the surface composition. The investigation was conducted at a base pressure of 6.5 × 10⁻⁹ Torr, resolution (Pass Energy) of 20 eV, and scan step of 0.05 eV/step. Fourier-transform infrared (FT-IR) spectroscopy (PerkinElmer, Waltham, MA, USA) was used to analyze the bonding arrangements of the samples.

Raman spectra were measured with a Thermo Scientific DXR3xi Raman Imaging Microscope equipped with an excitation laser wavelength of 532 nm (laser power of 10.0 mW) at room temperature. All Raman spectra were recorded by a 10× microscope objective. The exposure time was set as 0.5 s with 10 scans. The pinhole was 25 μm. The Raman spectra were obtained through capillary by wicking action and then baseline corrected by NGS LabSpec 5, normalized by peak intensity of 2260 cm⁻¹ from acetonitrile with Origin 8.5. UV–vis absorption spectra were recorded with a T6 UV-Vis spectrophotometer (Beijing Purkinje General Instrument Co., Ltd., Beijing, China). Medium scanning speed was used and the scanning interval was set as 0.2 nm. All solutions characterized by the UV–vis spectrophotometer were diluted a certain number of times in order to avoid excessive absorption values. TEM image of Ag NPs was recorded on a JEOL JEM-2100F field transmission electron microscope.

The cellular uptake of SSN was evaluated by a Raman technique based on the unique Raman signals of SSN. Briefly, Hepa 1–6 cells (1 × 10⁵) were seeded in a confocal dish, and cultured with SSN (100 µg mL⁻¹) for 4 h. After that, the culture medium was replaced with PBS, and the cellular uptake behavior was observed on a Raman microscope (Thermo Scientific, DXR3xi Raman Imaging Microscope).
For the convenience to observe the cellular uptake by fluorescence imaging, SSN were labeled with a near‐infrared fluorescent dye ICG by reaction with ICG‐PEG‐SH based on the Sn–S coordination. Hepa 1–6 cells (1 × 10⁵) were seeded in a confocal dish and cultured with the ICG labeled SSN (100 µg mL⁻¹) for 4 h. After that, the lysosomes and nuclei of Hepa 1–6 cells were stained with Lyso‐Tracker Green and DAPI, respectively. After the removal of excessive dyes and nanoparticles by washing, Hepa 1–6 cells were observed on a confocal laser scanning microscope (ZEISS, LSM880).

A DXR™3xi Raman-Imaging-Microscope (Thermo Fisher Scientific, Madison, WI, USA) equipped with an electron-multiplied CCD and a 532 nm laser providing 40 mW power at the sample was used in the present study. Raman mapping was carried out with a 25 µm lateral resolution using an Olympus 10× MPLN objective and with a 5 µm resolution using an Olympus 50× LMPLFLN objective. Raman spectra were collected at 400 Hz in 40 repetitions. The data collection time was around 6 h for a 12 × 12 mm² map registered with a spatial resolution of 25 µm and around 1 h for a 1 × 1 mm² map registered with a spatial resolution of 5 µm. A Multivariate Curve Resolution (MCR) was applied as a chemometric method with background subtraction and 5 estimated compounds to allow the algorithm to find the individual five components included in the liquisolid tablets, i.e., simethicone, TCP, DCPA, croscarmellose sodium, and magnesium stearate. For tablets labeled as “Simethicone/Loperamide TSG”, loperamide hydrochloride was added as the sixth component, and the MCR algorithm changed accordingly.