Helios alpha

All stock solutions for the PSBP was prepared at a concentration of 2 mg/mL via dissolution with DMSO. A 40~50 nm Au coated LSPR chip (Plexense. Co, Yongin-si, Korea) was thiol-conjugated by immersing it in the PSBP stock solution at 10× dilution (0.2 mg/mL) for 20 min. Then, the chip was immersed into the PS sample solution for 20 min to allow time for the chip to attach to the PS nanoplastic samples. The LSPR effect was analyzed to find out different absorbance intensity and wavelength shift by UV-Vis spectrophotometer (Helios Alpha, Thermo Scientific, Alva, UK; UV-1601, Shimazu, Kyoto, Japan). The scanning rate of UV-Vis spectroscopy was set to 3800 nm/min. For the scanning electron microscopy (SEM) analysis, using a field emission scanning electron microscopy (FE-SEM, SU-70, Hitachi Co., Osaka, Japan), surface of LSPR chip was analyzed. Because the LSPR chip was a nonconductive target, Au was used as a coating layer to enable SEM measurement. In addition, from a bench-top SEM (COXEM, EM-30AX, Daejon, Korea), microplastics dried on glass surface could be imaged with Au coating.

After centrifugation (10 min, 5000 rpm) to remove any suspended particles, absorbance was read at 420, 520, and 620 nm in a UV–VIS spectrometer (Helios alpha, Thermo Fisher Scientific, Waltham, MA, USA) to measure color characteristics of wines according to Glories [34 (link)]. The wine color intensity was calculated as the sum of the three measured absorbances, whereas wine hue was defined as the absorbance ratio at 420 and 520 nm. Moreover, the chromatic structure of wine was evaluated as the relative percentage (contribution in %) of each of the three measured components (420 nm yellow, 520 nm red, 620 nm blue) to the total color (sum of them).

Cell samples (1 mL) were extracted from the bulk P. tricornutum cultures and centrifuged at 15000g for 10 min. The supernatant was discarded, and dimethylformamide (1 mL, Fisher Scientific, UK) was added to the cell pellet to extract chlorophyll pigments. The samples were agitated at room temperature for 15 min using a shaker and then centrifuged for 2 min at 10000g. The absorbance of the supernatant at 630 nm and 664 nm was recorded using a spectrophotometer (Helios Alpha, Thermo Scientific, UK). The total chlorophyll content of the cell samples was calculated as follows: total chlorophyll content (μg/mL) = 23.96A₆₃₀ + 7.74A₆₆₄ [30 (link),31 (link)].