Ultrasensitive enrichment of phosphopeptides with Ti4+ immobilized SiO2 graphene-like multilayer nanosheets

Ti4+ immobilized SiO2 graphene-like multilayer nanosheets were designed and synthesized for the ultrasensitive enrichment of phosphopeptides with the detection limit of 1.0 pg μL−1 (4 × 10−17 mol μL−1). The enrichment selectivity of the nanosheets was evaluated by capturing phosphopeptides from a peptide mixture of bovine β-casein (β-casein) and bovine serum albumin (BSA) with the molar ratio of 1 : 1000 (1.7 × 10−12 mol of β-casein and 1.7 × 10−9 mol of BSA in 100 μL).