On-Chip Purification of Tetracyclines Based on Copper Ions Interaction

Abstract

Antibiotics are widely used to both prevent and treat bacterial diseases as well as promote animal growth. This massive use leads to the presence of residual antibiotics in food with severe consequences for human health. Limitations and regulations on the tolerated amount of antibiotics in food have been introduced and analytical methods have been developed. The bioanalytical methods usually employed to detect antibiotic residues, however, are time-consuming, expensive and laboratory-based. Novel methods with improved rapidity, portability and cost that are easy-to-use and sustainable are therefore highly desirable. In the attempt to fulfill this need, a microfluidic system was set up herein for the purification and pre-concentration of tetracyclines from raw milk selected as the case-study. The system includes a polymeric microfluidic chip containing magnetic beads loaded with copper to exploit the preferential interaction of tetracycline with divalent ions. The microfluidic system was demonstrated to efficiently pre-concentrate tetracycline, oxytetracycline and chlortetracycline with similar performances and efficiently purify tetracycline from raw milk without any pre-treatment. The simplified method described in this paper could be easily integrated in a compact and portable device for the in-field detection of tetracyclines, with the economic advantage of preventing food wastes and guaranteeing food safety.

Different Strategies for the Microfluidic Purification of Antibiotics from Food: A Comparative Study

“…Similarly, analogous data were obtained when TC spiked in raw milk was processed on PureCubeNHS beads functionalized with a-TC8 aptamer (TC/TC0 for the eluted fraction e2). Additionally, milk contains several compounds that could interfere with the aptamer–antibiotic binding [ 44 , 45 ], while this adverse effect is less present when the interaction of antibiotics is mediated by small molecules or even ions [ 20 ].…”

“…The third strategy considered for capturing antibiotics on the functionalized microbeads relies on the binding of small molecules to the beads surface in order to expose suitable chemical groups ( Figure 2 , strategy c). This strategy was demonstrated as very promising for TC purification by means of microbeads exposing copper ions [ 20 ], with the only limit to be valid solely for tetracyclines.…”

“…The binding test performed on the microfluidic chip was adapted from Lunelli et al [ 20 ] and is schematized in Figure 1 . Briefly, a microfluidic PMMA chip was mounted on the ChipGenie ®edition P device (microfluidic ChipShop, Jena, Germany; in Figure 1 b) and fluids were injected in the chip chamber inlets with two disposable syringes actuated by two syringe pumps (Legato 185, KD Scientific, Holliston, MA, USA; in Figure 1 a).…”

“…This requires a two-step process, i.e., a first phase, where antibiotics are bound and the food matrix is removed, and a second phase, where the release of the captured antibiotics is implemented, using a medium that is far more simple than the original matrix. Several different capture strategies can be exploited, based on molecular-imprinted polymers [ 14 ], antibodies [ 15 , 16 ], aptamers [ 17 , 18 , 19 ] and also taking advantage of specific interactions that the molecules of interest have with small functional groups [ 20 ].…”

On‐chip purification of tetracycline from food matrices

“…The eluted tetracycline was quantified via HPLC with a suitable method, previously setup. 16 F I G U R E 1 Scheme of the on-chip TC purification protocol. Two microsyringe pumps (A) inject the solutions in a microfluidic chamber (B) containing the microbeads, which expose copper ions (C).…”