Lab-on-a-chip for multiplexed biosensing of residual antibiotics in milk

Abstract

A multiplexed immunoassay-based antibiotic sensing device integrated in a lab-on-a-chip format is described. The approach is multidisciplinary and involves the convergent development of a multiantibiotic competitive immunoassay based on sensitive wavelength interrogated optical sensor (WIOS) technology and a polymer-based self-contained microfluidic cartridge. Immunoassay solutions are pressure-driven through external and concerted actuation of a single syringe pump and multiposition valve. Moreover, the use of a novel photosensitive material in a 'one step' fabrication process allowed the rapid fabrication of microfluidic components and interconnection port simultaneously. Pre-filled microfluidic cartridges were used as binary response rapid tests for the simultaneous detection of three antibiotic families -sulfonamides, fluoroquinolones and tetracyclines -in raw milk. For test interpretation, any signal lower than the threshold value obtained for the corresponding Maximum Residue Limit (MRL) concentration (100 mg L À1 ) was considered negative for a given antibiotic. The reliability of the multiplexed detection system was assessed by way of a validation test carried out on a series of six blind milk samples. A test accuracy of 95% was calculated from this experiment. The whole immunoassay procedure is fast (less than 10 minutes) and easy to handle (automated actuation).

Microfluidic phase change valve with a two-level cooling/heating system

“…In most microfluidic chip applications, pressure-driven flow, electroosmotic-driven flow, or a combination of both are commonly used as pumping methods (Suarez et al 2009;Borowsky et al 2008;Al-Gailani et al 2007). To accurately control sample transport, microvalves are one of the key elements to be integrated into the channel network.…”

Heterogeneous immunoassays in microfluidic format using fluorescence detection with integrated amorphous silicon photodiodes

“…Reduction in total reaction time has been achieved with several reports of assays with duration of 30 min or less. 14,18,[20][21][22][23] Ranges of sensitivity achieved are becoming comparable to those typically obtained in large scale size. 9,24,25 For example, 1.56 pg ml −1 was the limit of detection achieved for electrochemical detection of interleukin-6, 26 and 10 pM of Staphylococcal enterotoxin B could be detected using fluorescence detection with a PMT.…”

“…21 Other important advantages demonstrated in microimmunoassays were the small sample volume consumption 19,21,26 and assay automation. 15,23 The use of microfluidic immunoassays coupled with integrated miniaturized detection systems would allow the miniaturization of the full immunoassay. Miniaturization implies a reduction in the detection volume.…”

Recent Advances in Multiplex Immunoassays

“…Bioanalysis (2012) 4 (8) presented by Suarez et al and Adrian et al [36,37]. This system is fully integrated into a microfluidic plastic chip made by micromachining and UV micromolding.…”