Dmf n n dimethylformamide

Zinc oxide (ZnO) powder, graphite (C) powder, tin(IV) oxide (SnO₂) nanopowder with particle size <100 nm, poly(vinylidene fluoride-co-hexafluoropropylene) solution and DMF(N,N-dimethylformamide) were purchased from Sigma-Aldrich (Steinheim, Germany).
The experimental setup for the synthesis of hollow ZnO urchins includes a horizontal tube furnace and a gas supply system as reported previously [26 (link)]. A mixture of commercial C: ZnO: SnO₂ powders in a weight ratio of 1:1:0, 2:1:1 and 3:2:1 was ground and then used as the source material, located in a quartz boat and positioned at the centre of the quartz tube. The P-type silicon (111) wafer covered with gold nanoparticles (NPs) was used as a substrate (Si + Au) and was located downstream of the source materials, at the position where the temperature was 700 °C during the deposition. Thermal evaporation was conducted at 1000 °C for 30 min under atmospheric and nitrogen gas with a flow of 2 L/min, then the tube was kept isothermal for 30 min without any nitrogen gas supply. After the deposition, the heater was switched off to induce a cooling down period, while the uniformed thin layer was deposited on the Si + Au substrate.

The peptide PAH6 (Pal-H₆G₃KLAKLAKKLAKLAK-NH₂, MW 2755.43) was purchased from Canpeptide Inc. (Montreal, Québec, Canada) with the purity >95% (see Figure S4). Briefly, the peptide synthesis followed a solid-phase peptide synthesis method on Rink amide MBHA resin (AAPPTec, Louisville, KY, USA) manually with Fmoc (fluorenylmethyloxycarbonyl) chemistry. The deprotection of Fmoc (AAPPTec, Louisville, KY, USA) was conducted by the treatment with 20% piperidine (Sigma, Mississauga, ON, Canada) in DMF (N,N-dimethylformamide) (Sigma, Mississauga, ON, Canada), followed by coupling with the activated carboxyl group of the next amino acid. The coupling process was monitored with the Kaiser test. The synthesized peptide was cleaved from the resin with 95% TFA (trifluroacetic acid) (Sigma, Mississauga, ON, Canada). The purification of the peptide was performed using a Waters LC200 preparative system (Waters, Milford, MA, USA) equipped with a Phenomenex Gemini C18 column (Phenomenex, Torrance, CA, USA). Doxorubicin was purchased from LC laboratories (Woburn, MA, USA). The ATP-aptamer and its complementary DNA strand (sequences are listed in Table S1) were purchased from ThermoFisher Scientific (Mississauga, ON, Canada). All the other chemicals were purchased from Sigma-Aldrich unless otherwise specified.