Smartphone Optosensing Platform Using a DVD Grating to Detect Neurotoxins

Abstract

We present a smartphone optosensing platform (SOP) using a digital versatile disc (DVD) diffraction grating for rapid in-field detecting neurotoxins. The smartphone holder and sample holder were 3D printed for the SOP. A DVD grating is demonstrated for the first time in a low-cost miniature spectrometer on the SOP to quantify the concentrations of neurotoxins. The SOP is capable of detecting optical absorbance spectra within the entire visible spectral range from 400 to 700 nm with the spectral resolution of 0.2521 nm/pixel. We demonstrated the performance of the DVD grating compared with a commercial transmission grating on the SOP and a conventional microplate reader. Paraoxon, as the selected neurotoxin model, is assayed by two types of cholinesterase (ChE) on our SOP, respectively. Integrating a DVD grating in the SOP allows quantification of paraoxon in the range from 5 nM to 25 μM with the detection limit of 2.9 nM. In addition to the low assessed detection limit at medically relevant concentrations, the performance of SOP with DVD gratings provides new avenues for a point-of-care toxin diagnosis with time and cost savings.