Cellphone-based detection platform for rbST biomarker analysis in milk extracts using a microsphere fluorescence immunoassay

Abstract

Current contaminant and residue monitoring throughout the food chain is based on sampling, transport, administration, and analysis in specialized control laboratories. This is a highly inefficient and costly process since typically more than 99% of the samples are found to be compliant. On-site simplified prescreening may provide a scenario in which only samples that are suspect are transported and further processed. Such a prescreening can be performed using a small attachment on a cellphone. To this end, a cellphone-based imaging platform for a microsphere fluorescence immunoassay that detects the presence of anti-recombinant bovine somatotropin (rbST) antibodies in milk extracts was developed. RbST administration to cows increases their milk production, but is illegal in the EU and a public health concern in the USA. The cellphone monitors the presence of anti-rbST antibodies (rbST biomarker), which are endogenously produced upon administration of rbST and excreted in milk. The rbST biomarker present in milk extracts was captured by rbST covalently coupled to paramagnetic microspheres and labeled by quantum dot (QD)-coupled detection antibodies. The emitted fluorescence light from these captured QDs was then imaged using the cellphone camera. Additionally, a dark-field image was taken in which all microspheres present were visible. The fluorescence and dark-field microimages were analyzed using a custom-developed Android application running on the same cellphone. With this setup, the microsphere fluorescence immunoassay and cellphone-based detection were successfully applied to milk sample extracts from rbST-treated and untreated cows. An 80% true-positive rate and 95% true-negative rate were achieved using this setup. Next, the cellphone-based detection platform was benchmarked against a newly developed planar imaging array alternative and found to be equally performing versus the much more sophisticated alternative. Using cellphone-based on-site analysis in future residue monitoring can limit the number of samples for laboratory analysis already at an early stage. Therewith, the entire monitoring process can become much more efficient and economical.

Mobile Phones Create new Opportunities for Microbiology Research and Clinical Applications

“…In fact, mobile phone-based imaging and sensing platforms have already been used in a variety of applications, including clinical chemistry, biomedical and environmental monitoring [3][4][5], food analysis [6][7][8], detection of different types of chemical and biological analytes such as cells, parasites [9], bacteria [10], eggs [11], proteins [12], various biomarkers [6,7], nanoparticles [13] and even nucleic acids [14][15][16]. In many of these platforms, processing of the acquired data and the resulting computational analysis are done either on the smartphone or over a local or remote server using a customdeveloped smartphone application.…”

“…Smartphones have also been used as colorimetric readers [3,7,22], for example, to test antimicrobial drug susceptibility [23] and analyze ELISA-based tests, such as mumps immunoglobulin, measles IgG and herpes simplex virus IgG tests, with a very similar level of performance compared with US FDA-approved clinical well-plate readers [3]. This mobile phone-based 96-well reader design [3,7] is composed of a 3D printed opto-mechanical attachment unit that houses 96 multi-mode plastic fiber-optic cables that are each coupled to individual wells of a disposable well plate, enabling the measurement of the transmitted light from the wells, all in parallel and without the need for any mechanical scanning.…”

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KEYWORDSTogether with their cost-effectiveness, wide-spread use, computational power and connectivity, mobile phones have the potential to transform traditional uses of imaging, sensing and diagnostic systems, especially for point-of-care applications and field settings.In fact, mobile phone-based imaging and sensing platforms have already been used in a variety of applications, including clinical chemistry, biomedical and environmental monitoring [3][4][5], food analysis [6][7][8] [12], various biomarkers [6,7], nanoparticles [13] and even nucleic acids [14][15][16]. In many of these platforms, processing of the acquired data and the resulting computational analysis are done either on the smartphone or over a local or remote server using a customdeveloped smartphone application.

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Mobile-Phone Based Chemical Analysis - Instrumental Innovations and Smartphone Apps

“…Among smartphone-based analytical systems for other than clinical applications, one can find, for instance, a developed in recent years the mobile phone attachment for the detection of specific markers in milk ( Figure 2C). It detects antibodies, of which presence indicates a illegally used factor increasing milk production by cows [15]. The determination was carried out by fluorescence immunoassay employing quantum dots (QDs) coupled detection antibodies.…”

Early warning smartphone diagnostics for water security and analysis using real-time pH mapping

“…Such a smartphone technology is increasingly reported recently as a field-portable platform for many applications specially in bio-diagnostic and environmental monitoring. Most of these approaches are based on simple colorimetry [8][9][10][11][12][13][14][15][16], imaging [17][18][19][20][21][22][23], and spectroscopy [24][25][26][27]. Paper microfluidic devices are sometimes integrated to the calorimetric approaches [28][29][30][31][32][33][34][35].…”