N 2 aminoethyl maleimide trifluoroacetate salt

All chemicals were used as received without further purification. Ultra-pure water (18.2 MΩ.cm; Elga) was used for surface cleaning. O-(2-Carboxyethyl)-O′-(2-mercaptoethyl)heptaethylene glycol (≥95%; HS-EO₇-COOH), N-(2-Aminoethyl)maleimide trifluoroacetate salt (≥98%), N-hydroxysuccinimide (98%; NHS), N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (≥98%; EDC), 2-(N-Morpholino)ethanesulfonic acid hydrate (≥99.5%; MES), absolute ethanol (≥99.8%), methanol (≥99.6%) and sulfuric acid (85.0–98.0%) were purchased from Sigma-Aldrich, France. Hydrogen peroxide (35% w/w in water) was purchased from Alfa Aesar, Germany. Custom synthesized HS-CH₂-CH₂-CO-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂ peptide (≥98%; α-MSH) was obtained from Genecust, Luxemburg. Gold coated glass slides (300 nm thickness evaporated gold on glass-plates with an intermediate layer of Cr/Ni) were purchased from Applications Couches Minces, Paris.

LMWP (VSRRRRRRGGRRRR) and TAT (CGGGYGRKKRRQRRR) peptides were purchased from Bankpeptide Biological Technology Co., Ltd. (Hefei, China). Paclitaxel (PTX) was purchased from Dalian Meilun Biotech Co., Ltd. (Dalian, China). N-(2-Aminoethyl) maleimide trifluoroacetate salt was purchased from Sigma-Aldrich Co., LLC (St. Louis, MO). Trifluoroacetic acid (TFA), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), N-hydroxysuccinimide (NHS), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC), and N,N-diisopropylethylamine (DIPEA) were purchased from aladdin-e.com (Shanghai, China). JC-1, propidium iodide (PI) and annexin V-FITC were purchased from Univ Biological Technology Co., Ltd. (Shanghai, China). Dichloromethane (DCM) and anhydrous dimethyl sulfoxide (DMSO) were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).