Controllable synthesis and adjustable antineoplastic activity of bovine serum albumin‐conjugated PbS/Ag2S core/shell nano-composites

► A facile and gently method was developed to fabricate core/shell nano-composites. ► The shell thickness and ratio of Pb to Ag could be controlled by ion-exchange time. ► The inhibition of nano-composites on tumor cells was Pb/Ag ratio-dependent. ► The synergistic effect of metal ions on tumors holds promise for tumor treatment.