**2. Materials and Methods**

#### *2.1. Materials*

In this study, CQDs were produced from three different biomass precursors. Of them, 5-hydroxymethylfurfural (HMF) was purchased from Carbosynth LLC. (San Diego, CA, USA). Meanwhile, furfural was purchased from Sigma-Aldrich (St. Louis, MO, USA). On the other hand, microcrystalline cellulose (extra pure, avg. particle size 90 μm) was

purchased from Acros Organics (Fair Lawn, NJ, USA). Analytical-grade ethanol was purchased from Fisher Scientific (Waltham, MA, USA).
