2 mercapto 4 methyl 5 thiazoleacetic acid

1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethyleneglycol)-2000] (ammonium salt) (DSPE-PEG2000-NH₂) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl) (ammonium salt) (PE-NBD) were purchased from Avanti Polar Lipids, USA. Cholesterol (Chol), hydrogen tetrachloroaurate (III) trihydrate (HAuCl₄•3H₂O) and silver nitrate (AgNO₃) were purchased from Alfa Aesar. Doxorubicin (DOX), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), N-hydroxysuccinimide (NHS) and 2-mercapto-4-methyl-5-thiazoleacetic acid (MMTAA) were purchased from Sigma Aldrich. Methanol, chloroform and Triton X-100 were purchased from Aladdin Reagent Co., Ltd. Trisodium citrate (Na₃C₆H₅O₇•2H₂O) was purchased from Sinopharm Chemical Reagent Co., Ltd. Phosphate buffered saline (PBS, 10mM, pH 7.4) was purchased from Nanjing KeyGen Biotechnology Co., Ltd. All the reagents were used as received. Deionized water (Millipore Milli-Q grade) with a resistivity of 18.2 MΩ cm^-1 was used in all the experiments.

CNOs were obtained according to the method proposed by Kuznetsov,^{72 (link)} in which diamond nanoparticles (NDs, Carbodeon µDiamond Molto) with a diameter of 4.2 ± 0.5 nm and a ND content of ≥97 wt% were annealed. All the chemicals and solvents were commercially available and used without further purification: nanodiamond powder (µDiamond®Molto, Carbodeon); 1,2-dicyanobenzene (∼98%, Sigma-Aldrich); ammonia solution (25% pure p.a., Sigma-Aldrich); maleimide (∼99%, Sigma-Aldrich); tetrahydrofuran (pure p.a., Avantor); 2-propanol (pure p.a., Avantor); acetone (99.5% pure p.a., Avantor); 2-mercapto-4-methyl-5-thiazoleacetic acid (∼98%, Sigma-Aldrich); zinc chloride (≥99%, Sigma-Aldrich); nickel(ii) chloride (∼98%, Sigma-Aldrich); copper(ii) chloride (∼97%, Sigma-Aldrich); hydrochloric acid (35–38% pure p.a., Avantor); sulphuric acid (95% pure p.a., Avantor); sodium chloride (pure p.a., Avantor); aluminium powder (∼99.99%, Avantor); sodium (Sigma); 1-octanol (≥95%, Sigma-Aldrich); potassium permanganate (Avantor); dimethyl sulphoxide (DMSO, pure p.a., Avantor); and methanol (99.5% pure p.a., Avantor).