Letter pubs.acs.org/ac
Portable Upconversion Nanoparticles-Based Paper Device for Field Testing of Drug Abuse Mengyuan He, Zhen Li, Yiying Ge, and Zhihong Liu* Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, China State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan 410082, P. R. China S Supporting Information *
ABSTRACT: We report the first portable upconversion nanoparticles (UCNPs)-based paper device for road-side field testing of cocaine. Upon the recognition of cocaine by two pieces of rationally designed aptamer fragments, the luminescence of UCNPs immobilized on the paper is quenched by Au nanoparticles (AuNPs), which indicates the cocaine concentration. This device can give quantitative results in a short time with high sensitivity using only a smartphone as the apparatus. Moreover, this device is applicable in human saliva samples, and it also can be used to monitor the cocaine content change in blood samples. The results of this work demonstrate the prospect of developing UCNPs-based paper devices for field testing of drug abuse.
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as a consequence of their features of excitation with nearinfrared (NIR) light and anti-Stokes emission.19−26 In 2013, we reported the first UCNPs and paper matrix-based biosensor,27 and thereafter, a series of sensors and devices have been developed for various analytes including oligonucleotides, proteins, and small molecules.28−33 The reported works have demonstrated the satisfying performance of this kind of assay in complicated samples. However, all of them are still limited to laboratory research relying on instrumental read-out, and no portable device for field testing has been built yet. We herein report a portable UCNPs-based paper device for the sensitive and quantitative on-site detection, taking cocaine as the proof-of-concept target, which uses only a smartphone as the apparatus with simple data processing (Scheme 1). The target recognition is realized by using an anticocaine aptamer (ACA), which has been used to develop several cocaine sensors in recent years involving optical and electrical assays.34−39 The target concentration is indicated by the attenuation of the luminescence of UCNPs. To this end, the aptamer ACA is rationally cut into two flexible ssDNA pieces, namely, ACA-1 and ACA-2 (the sequences are provided in the Supporting Information). UCNPs functionalized with poly(ethylenimine) (PEI) and amine modified ACA-1 are covalently coupled on the surface of a cellulose filter in advance. Sulfhydryl modified ACA-2 is attached to gold nanoparticles (AuNPs) by Au−S chemistry. When no target exists, there is no interaction between the two pieces of ssDNA and the luminescence of
rug abuse has become one of the most concerned social and health problems all over the world.1,2 To meet the requirement of timely detection and on-site screening, it is of great importance to develop methods and devices that are suitable for road-side field testing of drugs. However, until now, this has remained a big challenge. Taking cocaine, the second most used illegal substance in both Europe and United States, as the example, to date, there has been no method available for accurate field testing. Although there are some established and accurate laboratory techniques for cocaine, such as gas or liquid chromatography combined with mass spectroscopy (LC/GC/ MS), they obviously are unsuitable for field testing because of the need of a sophisticated procedure and expensive instrumentation.3−7 Currently, the most often used on-site detection method for cocaine is the immunoassay, which can give a positive/negative judgment. The positive immunoassay results, however, still require a second instrumental determination in the laboratory for further quantitative estimation.8−10 Paper has drawn increasing attention as a support material for fabrication of sensors and devices in analytical and clinical chemistry in the past years, owing to its portability, simplicity, and low cost.11−18 We are motivated to speculate that optical detection techniques, such as luminescence with the merit of visualization and hence the independence of large equipment, may have the potential to develop portable devices for field testing when combined with paper matrix. Further, in consideration of the high complexity of the testing samples (mainly body fluids) which always raise interference in assays, upconversion nanoparticles (UCNPs) can be promising luminescent materials for the construction of such devices and sensors for their strong ability to circumvent interference, © XXXX American Chemical Society
Received: December 22, 2015 Accepted: January 20, 2016
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DOI: 10.1021/acs.analchem.5b04863 Anal. Chem. XXXX, XXX, XXX−XXX
Letter
Analytical Chemistry
porous structure of the paper matrix (Figure S-5a,b) and that PEI-UCNPs were successfully immobilized on the surface of paper with an excellent dispersibility (Figure S-5c). The signal intensity of UCNPs immobilized on the paper kept stable for more than 4 months when stored in a dry environment at 4 °C (Figure S-6a). Furthermore, the high reproducibility was indicated by the small interbatch coefficient of variation between three independently produced paper devices (
