A Hybrid Lab-on-a-Chip Injector System for Autonomous Carbofuran Screening

Abstract

Securing food safety standards is crucial to protect the population from health-threatening food contaminants. In the case of pesticide residues, reference procedures typically find less than 1% of tested samples being contaminated, thus indicating the necessity for new tools able to support smart and affordable prescreening. Here, we introduce a hybrid paper–lab-on-a-chip platform, which integrates on-demand injectors to perform multiple step protocols in a single disposable device. Simultaneous detection of enzymatic color response in sample and reference cells, using a regular smartphone, enabled semiquantitative detection of carbofuran, a neurotoxic and EU-banned carbamate pesticide, in a wide concentration range. The resulting evaluation procedure is generic and allows the rejection of spurious measurements based on their dynamic responses, and was effectively applied for the binary detection of carbofuran in apple extracts.

Smartphone-based optical assays in the food safety field

“…To date, there is a lack of such systems, especially in the case of solid food matrices. To develop μTAS the use of 3D-printing technology is highly recommended as cost-efficient, lightweight and practical solutions with short fabrication time can be developed [ 16 ].…”

“… n.a. 56 days [ 16 ] chlorpyrifos, diazinon, and malathion vegetables and fruits fluoresent aptamer LFIA with diffraction grating and pixel to wavelength conversion chlorpyrifos 0.73 ng mL −1 , diazinon 6.7 ng mL −1 , malathion 0.74 ng mL −1 chlorpyrifos: lowest possible diazinon & malathion: depending the matrix n.a. n.a.…”

“…Panel reprinted from Ref. [ 16 ] under CC BY 4.0 [ 54 ]. In this example, the response primarily modulates in the blue region.…”

“…The apparent lack of correlation between assay colour and optimum channel choice may be attributed to metamerism causing limited correlation between perceived colour and spectral variance related to the analytical signal. Thus, measuring the spectral reflectance of the assay to determine in which bandwidth the variation of the analytical signal falls may be prudent [ 16 ] ( Fig. 3 b).…”

“…2 b inset; Table 2 ), should be considered. Worthy to notice is that in the same study [ 16 ], video recording of the assay was used instead of photo capturing, enabling the dynamic recording of the tested enzymatic reaction. In this way, an internal quality system is able to reject spurious measurements, based on principal components analysis (PCA).…”