Silk Extraction and Ionization Protocol

Silk from Bombyx mori was sourced from the cocoons of sericulture silkworms maintained in the facilities of IMIDA (Murcia, Spain) and fed on fresh Morus alba L. leaves. The cocoons were treated to remove the sericin by boiling in an aqueous solution of Na₂CO₃ (0.05 N) twice for 60 min. After washing with pure water and air-drying, the resulting substance had a bright white, cotton-like appearance. The silk was dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate [emim+][acetate−] by high-power ultrasound, as described in a previous report [12 (link)]. The ionic liquid (97% purity) was obtained from Io-LiTec GmbH (Frankfurt, Germany) and was applied without any further purification. Ibrutinib (IB) [38 (link)] (Figure S1 of Supporting Information) was provided by AdooQ Bioscience (Irvine, CA, USA). Highly purified water (18.2 MΩ·cm at 25 °C; from a Millipore Direct-Q1 ultrapure water system, Billerica, MA, USA) was used throughout. N-Hydroxysuccinimide (NHS) and N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) were purchased from Merck. All other chemicals and solvents were of analytical grade and were used without any extra purification.