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Caption : fig. s1: sers spectrum of 4-(1h-pyrazol-4-yl) pyridine (ppy) taken on a cbex snowy range handheld raman spectrometer. a 785 nm laser excitation was used with a laser power of 75 mw and an integration time of 0.2 seconds. the structure of ppy is included.

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Caption : fig. s2: (a) normalised extinction spectra of ppy-aunp-shins (blue, diluted 1 in 4), ab nanotags (red, undiluted), and cab nanotags (yellow, undiluted). (b) lateral flow immunoassay where i) shows the presence of a line and therefore binding of the ab nanotags, ii) shows the absence of a line and therefore the lack of binding of the nanotags with no ab attached identified by the red marker.

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Caption : fig. s3 2d direct classical least squares (dcls) single u87-mg cell uptake study on carried out on n=3 cells (i) ab nanotags and (ii) cab nanotags. (a) tracking of the 2930 cm-1 peak of the ch3 protein cellular stretch, using a 532 nm laser excitation. (b-d) tracking of the main ppy peak at 956 cm-1, using a 785 nm laser excitation through three different planes of the cell. all spectra were taken using a 2.5 µm step size, 1 s integration time and 100% laser power (785 nm, 20 mw and 532 nm, 30 mw).

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Caption : fig. s4: (a) example of the physical colour change of the mts after incubation with the ab nanotags at 32 pm and 64 pm. clearly, an increase in concentration results in a deeper purple colour. (b) examples of mts with their size indicated.

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Caption : fig s5: 2d xy raman intensity map at 2930 cm-1 showing the ch3 cellular protein peak carried out on n = 3, obtained using 532 nm laser excitation taken at the middle of the spheroid used in fig. 1. spectra were taken using a 20 µm step size, 1 s integration time and 100% laser power (30 mw), with a 532 nm laser excitation.

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Caption : fig. s6 2d xz sers intensity maps at 956 cm-1 corresponding to the main intensity peak of the raman reporter ppy of the nanotags in mts incubated with (a) ab nanotags and (b) cab nanotags for 4 hours in y = 50 µm increments. all spectra were taken using an x = 10 µm, z = 50 µm step size, a 1 s integration time and 100% laser power of 20 mw and a 785 nm laser excitation. all measurements were taken on n = 3 mts.

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Caption : fig. s7 2d xz sers intensity maps at 956 cm-1 corresponding to the main intensity peak of the raman reporter ppy of the nanotags inside mts incubated with (a) ab nanotags and (b) cab nanotags for time and concentration comparisons.  i) 32 pm 4-hour incubation, ii) 128 pm 4-hour incubation, iii) 32 pm for 24 hours and iv) 128 pm 24 hours. all spectra were taken using an x = 10 µm, z = 50 µm step size, a 1 s integration time and 100% laser power (20 mw), with a 785 nm laser excitation. all measurements were taken on n = 3 mts.