a, Schematic illustrating steps of SWNT-SHP1i preparation. Following SWNT-PEG-Cy5.5 (SWNT-Cy5.5) fabrication, SHP1i is loaded onto SWNT-Cy5.5 by adding SHP1i to a stirred solution of SWNT-Cy5.5 overnight at 4 °C and removing free SHP1i molecules by dialyzing with PBS for 24h at 4 °C. DSPE-PEG: 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)]. b, Chemical structure of the small-molecule inhibitor of SHP-1. c, Release rates of SHP1i from SWNT-Cy5.5 in PBS (pH=7.4). d, Of the various PEG lengths tested, PEG 5000 provided the highest yield (3.5x higher than PEG 2000 ). SWNTs were thus functionalized with PEG 5000 for in vitro and in vivo studies. e-f, Photos depicting color change in the SWNT-Cy5.5 filtrate demonstrating removal of excess Cy5.5 (blue color) after each washing step (e), and after loading SWNT-Cy5.5 with SHP1i (red-tinted solution on right) (f). g, Attenuated total reflectance (ATR) infrared spectra for SWNT-SHP1i, SWNT-Cy5.5, and SHP1i. The major spectral features of SHP1i are located in the fingerprint region, containing a complex set of absorptions. The S-O stretch from SO 3 - in the SHP1i molecule observed at 1034 cm-1 in SHP1i spectra is recapitulated in the SWNT-SHP1i spectrum as an additional spike at 1034cm-1 in comparison with the SWNT-Cy5.5 spectrum (highlighted in square). These data confirm loading of SHP1i on SWNTs together with UV-vis spectra and the color change of the solution. Data in c-g were repeated 3 times with similar results. h, Quantification of endotoxin levels reveals that SWNT-PEG, SWNT-Cy5.5, and SWNT-SHP1i each have endotoxin levels <0.01 ng/mL (approximately 0.1 endotoxin units per mL; standard curve provided). The assay was performed once with 3 biological replicates. Mean and standard error of the mean (s.e.m.) are shown.