Use of Carbon Nanotubes as a Solid Support To Establish Quantitative (Centrifugation) and Qualitative (Filtration) Immunoassays To Detect Gentamicin Contamination in Commercial Milk

Current methods to detect gentamicin (GEN), a broad-spectrum antibiotic that causes ototoxicity and nephrotoxicity when present in excess, have several limitations. Hence, we have developed two methods using multi-walled carbon nanotubes (MWCNTs) as a solid support to detect GEN. Hybridoma cells (2D12) producing high-sensitivity antibodies against GEN were established. The goat anti-mouse antibody was immobilized on MWCNTs directly or using bifunctional polyethylene glycol as a linker. On the basis of the physical characteristics of MWCNTs, a quantitative method involving centrifugation separation and a qualitative method involving filtration separation were established. Various experimental parameters were optimized for GEN detection, and recovery tests were performed. For the quantitative method, the limit of detection (LOD) was 0.048 ng/mL, whereas for the qualitative method, a LOD of 0.1 ng/mL was observed by the naked eye. The proposed immunoassays were applied to commercial milk samples. Thus, these methods show potential application for the detection of GEN.