▎ 摘　　要

Folic acid (FA) encapsulated graphene quantum dots (FA-GQDs) were prepared via a one-pot microwaved alkali cutting method, using graphene oxide (GO) and FA as raw material. TEM and AFM images revealed that FA was successfully cross-linked on the surface of GQDs under alkali circumstance, giving rising to stable and homogeneous FA-GQDs with size of about 33.6 nm. XPS and FT-IR confirmed that there are abundant hydroxyl, carboxyl and amino groups on the encapsulated FA-GQDs. The as-prepared FA-GQDs possessed the fluorescence behaviors of multi-excitation and emission sites, and exhibited sensitive response to the pH variation within the pH range of 3-9, making it excellent fluorescence probe for pH sensing in cell lysate and environmental water samples. The broad emission with pH-sensitive characteristic and low toxicity of FA-GQDs also provided an alternative for the specific multicolor imaging and sensing of pH in living cells. (c) 2018 Elsevier B.V. All rights reserved.