Dxr2xi

The prepared porous Ag crystals were characterized by scanning electron microscope (SEM, SU8010, Hitachi, Japan) and transmission electron microscope (TEM, Tecnai G2 F20 S-TWIN). The SEM study was conducted on a JEOL JSM-6700F SEM running at 3.0 kV. A Hitachi HT7700 operating at 100 kV was used for TEM characterization. Surface-enhanced Raman spectroscopy was performed using a confocal Raman microscope (Thermo Fisher DXR2xi) with a laser excitation at 633 nm, an exposure time of 10 s and an objective lens with a magnification of 50 times.

The samples were prepared by seeding PC-3 and PNT-2 cells onto the 2D BP flakes for different time intervals of 10 h, 24 h, 48 h, and 72 h. Afterwards, fixation of the samples for Raman measurements was performed using 4% formaldehyde overnight at 4 °C, followed by washing for three times and storing in PBS 1X until Raman analysis. Raman maps of the treated and untreated cells were then acquired with a DXR2xi Thermo Fisher Scientific (Waltham, MA, USA) Raman imaging microscope by exciting the samples at 532 nm with 2 mW laser power and a 50× objective. Each point spectrum resulted from 30 accumulations of 0.1 s acquisitions, and the maps were collected over a square area with a fixed step size of 1 μm. Each map contained several cells and many 2D BP flakes, localized inside, near, and far from the cells depending on the cell status, type, and time interval from the seeding. For every map, the 2D BP aggregates were visually and spectrally identified, and the corresponding point spectra were individually analyzed by means of a Lorentzian fitting procedure to extract the FWHM of the three peaks ascribed to 2D BP. For each time interval, the fitting results were used to build separate histograms for 2D BP decorating the cells or far away from them.

The prepared 10 μL Au nanoparticles were dropped onto the cleaned glass slides, and then 10 μL R6G solutions of different concentrations were added. The solution was pumped and mixed evenly and dried at room temperature to prepare the surface-enhanced Raman spectroscopic detection substrate. A laser Raman spectrometer (Thermo Fisher DXR2xi) equipped with microscope and CCD detector was used to record SERS spectra. The laser wavelength used in the experiment is 633 nm, the acquisition time is 10 s, and the laser power is 6.0 mW. The objective lens (OLYMPUS 50X 0.75 BD) magnification is 50 times. All the collected spectra are baselines corrected by OMNIC for Dispersive Raman, a software provided with the equipment, and later used for analysis. The distribution of the Raman Peak is analyzed by using the matching software OMNIC for Dispersive Raman.