Environmentally benign sensing platform for label free detection of Fe3+ and tobramycin using highly fluorescent carbon dots valorized from sweet potato roasting residues

Abstract

A novel sustainable source with zero intended energy consumption is introduced for the first time for obtaining carbon dots (CDs). These CDs were spontaneously formed during the ordinary roasting of sweet potato (SPCDs) with a yield of 160.54 mg/kg. The obtained SPCDs exhibited high fluorescence quantum yield (53%) at 442 nm after excitation at 360 nm, narrow particle size distribution (3.54 ± 1.08 nm) and negative zeta potential (-12.2 mV). Using the obtained SPCDs, a sensitive, selective, rapid, and effortless turn off–on fluorescent sensing platform was constructed for label free detection of the non chromophoric drug, tobramycin (TOB). The proposed sensing strategy was based on the possible Fe3+ induced mixed mode static quenching/inner filter effect and fluorescence recovery through its complexation by TOB. The sensor demonstrated good performance for TOB detection with a linear range of 10.69 – 106.90 µM (5–50 µg/mL). The sensing platform was successfully applied for TOB detection in its ophthalmic solution, with good accuracy (100.39% ± 2.19) and precision (RSD, 2.18%), and can be adopted for its routine analysis without any chemical derivatization. Moreover, the developed sensor was successfully applied for TOB detection in real samples including honey and river water. Such sustainable and cost-effective carbon dots require neither special equipment nor hazardous chemicals so that it can be adopted as a source for CDs.