A Portable Smartphone Platform Using a Ratiometric Fluorescent Paper Strip for Visual Quantitative Sensing

Abstract

Instrument-free, portable, and direct read-out minidevices have wider application prospects in various fields, especially for real-time/on-site sensing. Herein, combined with a paper strip, a smartphone sensing platform integrated with a UV lamp and dark cavity by 3D-printing technology has been developed for the rapid, sensitive, instrument-free, and visual quantitative analysis in real-time/on-site conditions. The platform proved the feasibility for visual quantitative detection of pesticide via a fluorescence "on−off−on" response with a single dualemissive ratiometric paper strip. Red-emitting CdTe quantum dots (rQDs) were embedded into the silica nanoparticles (SiO 2 NPs) as an internal reference, while blue-emitting carbon dots (bCDs) as a signal report unit were covalently linked to the outer surface of SiO 2 NPs. The blue fluorescence could be quenched by gold nanoparticles (Au NPs) and then recovered with pesticide. The red (R), green (G), and blue (B) channel values of the generated images were determined by a color recognizer application (APP) installed in the smartphone, and the R/B values could be used for pesticide quantification with a sensitive detection limit (LOD) of 59 nM. The smartphone sensing platform based on 3D printing might provide a general strategy for visual quantitative detection in a variety of fields including environments, diagnosis, and safety monitoring.

Sensitive and selective determination of tetracycline in milk based on sulfur quantum dot probes

“…Apparently, TC hardly affects the uorescence lifetime of SQDs, indicating the absence of uorescence resonance energy transfer (FRET) and dynamic quenching effect (DQE) because the uorescence lifetime of SQDs will be shortened in the presence of TC when these two mechanisms exist. 47,48 It can be speculated that the uorescence quenching may result from the SQE or IFE between SQDs and TC. It is considered that the spectral overlap between absorption spectra of the quencher and the excitation spectra of the uorophore will result in IFE.…”

Cost-Effective Tween 80-Capped Copper Nanoparticles for Ultrasensitive Colorimetric Detection of Thiram Pesticide in Environmental Water Samples

“…Journal of Nanomaterials [6,[30][31][32][33]. The shift of the stretching vibrational band of υ(C-S) asym to a high frequency of about 15 cm -1 upon interaction with CuNPs often suggests that the delocalisation of electron will affect the C-S bond [31].…”

“…Dithiocarbamates (DTC) have numerous applications in chemical [3], agriculture [4], and the pharmaceutical industry [5], etc. Thiram (tetramethylthiuram disulfide) is a kind of typical DTC pesticide and fungicide which has been widely used to prevent various crop diseases [6]. However, its overuse has caused serious environmental hazards such as soil pollution and even seep into groundwater or mixed with air dust, therefore, becoming a serious threat to human health [7,8].…”

Ratiometric Fluorescent Lateral Flow Immunoassay for Point‐of‐Care Testing of Acute Myocardial Infarction

“…[15] Moreover,t he hue changes along with the intensity variations of three primary colors (red-green-blue,R GB), hence the signal intensity ratio of different colors,such as R/G,can be utilized to quantify the target concentration with portable terminal devices (such as smartphone). [16] Theuniversal design strategy for hue evolution is based on ratiometry with either af ixed reference signal or two reverse signal changes.B yc ontrast, the latter presents amore sensitive intensity ratio change,and its sensitivity is on the same order of magnitude with the spectral analysis. [17] However,the utilization of double-signalresponsive strategy for the detection of protein biomarkers is still scarce,a lthough it possesses ah igh sensitivity for visualization and is achievable via the energy transfer model.…”