Surface plasmon resonance based sensor for the detection of glycopeptide antibiotics in milk using rationally...

Glycopeptide antibiotics are known as the last resort for the treatment of serious infections caused by Gram-positive bacteria. The use of milk products contaminated with these antibiotic residues leads to allergic reactions and sensitivity in human. Also, long-term consumption of milk products containing low levels of these antibiotics may cause the relevant bacteria to build up resistance to these last resort antibiotics. Sensitive, rapid and effective quantification and monitoring systems play a key role for their determination in milk products. Hence, molecularly imprinted nanostructures were rationally designed in this work to produce high affinity synthetic receptors to be coupled with a surface plasmon resonance sensor for the analysis of glycopeptide antibiotics in milk samples. The nanoMIP-SPR sensor enabled vancomycin quantification with the LODs of 4.1 ng mL^-1 and 17.7 ng mL^-1 using direct and competitive assays, respectively. The recoveries rates for two sensor methods ranged in 85-110% with RSDs below 7%. The affinity between the nanoMIP receptors and the target molecule (dissociation constant: 1.8 × 10^-9 M) is mostly superior to natural receptors and other synthetic receptors. Unlike other methods commonly employed for the detection of milk contaminants this approach is extremely simple, fast and robust, and do not require pre-sample treatment.