GoKawiilPreparation of SWCNTs
If not stated otherwise, all chemicals were purchased from Sigma Aldrich (Germany). Unless specifically stated, all experiments were performed with (6,5)-enriched SWCNTs (Sigma Aldrich, Signis SG65i, CoMoCAT synthesis technology). For DNA-functionalized SWCNTs 150 µl of 2 mg ml−1 single-stranded DNA (for example, (GT) 10 ) in 1× PBS buffer (pH 7.4) was mixed with 75 µl of 2 mg ml−1 SWCNT in PBS and 75 µl PBS, followed by tip sonication (Fisher Scientific, FB120, 120 W, amplitude 35%, 9 s pulse on and 1 s off, 15 min). The obtained solution was centrifuged for 30 min at maximum speed (21,000g), the supernatant was collected, and the procedure was repeated two more times. The final supernatant was stored at 4 °C until further experiments were performed. For (GT) 10 -SWCNT experiments in D 2 O, the PBS buffer was prepared with D 2 O instead of H 2 O.
The separation via aqueous two phase extraction (ATPE) of (6,4)-SWCNTs was performed according to the following protocol48. (DOC)-SWCNTs were mixed with polyethylene glycol (PEG) (molecular weight 6 kDa, 8% w/v), dextran (Carl Roth, molecular weight 70 kDa, 4% w/v), and the surfactants DOC (0.025% w/v), SDS (0.5% w/w) and SC (ranging from 0.5% to 0.9% w/w in 0.1% increments). The chiralities of SWCNTs in the two phases could be adjusted by adding HCl. Then, a one-step approach was used by adding a specific volume of HCl (hydrogen chloride) and NaClO (sodium hypochlorite) with 10–15% available chlorine for pH-driven and electronic separation, allowing the collection of monochiral (6,4)-SWCNTs in the bottom phase (B3). The solution was then dialysed (using a 300 kDa dialysis bag, Spectra/Por, Spectrum Laboratories) against a 1% DOC solution to remove dextran and obtain a stable 1% DOC-(6,4)-SWCNT solution.
For DOC-SWCNTs, 150 µl 2% (m/v) DOC in H 2 O was mixed with 150 µl of 2 mg ml−1 SWCNTs (in H 2 O), followed by tip sonication and centrifugation similar to the conditions for (GT) 10 -SWCNTs preparation. The acquired supernatant was stored at 4 °C. SDBS- and SC-functionalized SWCNTs were prepared according to the same procedure as DOC-SWCNTs.
Quantum defect introduction was performed according to a previously developed protocol49. Briefly, 20 µl of 4 mM 4-nitrobenzol diazonium tetrafluoroborate diazonium salt (dissolved in water) was added to 20 ml of 10 nM SDBS-SWCNTs solution. Then the mixture was irradiated with green light (550 nm) while stirring for 15 min. The obtained solution was mixed with the same volume of acetonitrile (ACN) and, consequently, the SWCNTs precipitated. The pellet was then washed with H 2 O two or three times to remove residual SDBS and ACN. Finally, the acquired precipitate was redispersed in 1% DOC by 15 min tip sonication followed by centrifugation for 30 min at 21,000 g. The collected supernatant was used for the experiments. The length of SWCNTs prepared by this procedure is about 600 nm (ref. 25).
All samples were colloidally stable in aqueous solution without signs of aggregation as confirmed by absorbance (Extended Data Figs. 1a and 2, and Supplementary Fig. 1), one-dimensional (1D) (Extended Data Fig. 1b,c) and two-dimensional (2D) fluorescence spectroscopy (Supplementary Figs. 2 and 3) and atomic force microscopy (average SWCNT length of around 600 nm; Supplementary Figs. 4 and 5). We also prepared chirality-pure (6,5)- and (6,4)-SWCNTs to exclude effects from impurities (Extended Data Fig. 2 and Supplementary Fig. 1).
NIR spectroscopy
One-dimensional fluorescence spectra
One-dimensional spectra of 0.5 nM (GT) 10 -SWCNTs with or without analytes (2 μM riboflavin and 100 μM ascorbic acid in aqueous solution) or 0.5 nM DOC-, SC- and SDBS-functionalized SWCNTs were measured in a custom-built setup based on an Olympus IX73 microscope and a solid-state laser (Quantum gem-561, 561 nm). The emission spectra were captured with an Andor iDus InGaAs 491 array NIR detector coupled to a Shamrock 193i spectrometer (Andor Technology).
Two-dimensional fluorescence spectra
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