A low-cost smartphone-based platform for highly sensitive point-of-care testing with persistent luminescent phosphors

Abstract

Through their computational power and connectivity, smartphones are poised to rapidly expand telemedicine and transform healthcare by enabling better personal health monitoring and rapid diagnostics. Recently, a variety of platforms have been developed to enable smartphone-based point-of-care testing using imaging-based readout with the smartphone camera as the detector. Fluorescent reporters have been shown to improve the sensitivity of assays over colorimetric labels, but fluorescence readout necessitates incorporating optical hardware into the detection system, adding to the cost and complexity of the device. Here we present a simple, low-cost smartphone-based detection platform for highly sensitive luminescence imaging readout of point-of-care tests run with persistent luminescent phosphors as reporters. The extremely bright and long-lived emission of persistent phosphors allows sensitive analyte detection with a smartphone by a facile time-gated imaging strategy. Phosphors are first briefly excited with the phone’s camera flash, followed by switching off the flash, and subsequent imaging of phosphor luminescence with the camera. Using this approach, we demonstrate detection of human chorionic gonadotropin using a lateral flow assay and the smartphone platform with strontium aluminate nanoparticles as reporters, giving a detection limit of ≈45 pg/mL (1.2 pM) in buffer. Time-gated imaging on a smartphone can be readily adapted for sensitive and potentially quantitative testing using other point-of-care formats, and is workable with a variety of persistent luminescent materials.

Recent Progress in Optical Biosensors Based on Smartphone Platforms

“…This has created unexpected opportunities for expanding the diagnostic and the prognostic approach to a large number of pathologies and for evaluating pharmaceutical therapies. With the aid of 3D-print technology, smartphone-based systems with 3D-printed cradles which were used to fix attachments have been explored in diagnostic field [ 8 , 9 , 10 ], food safety [ 11 , 12 ], environmental monitoring [ 13 ] and physical condition [ 3 , 14 ]. Though there are many different biosensor platforms based on smartphones, high-quality camera lenses on smartphones are a critical part and applied extensively for different smartphone biosensor platform.…”

Recent Progress in Time‐Resolved Biosensing and Bioimaging Based on Lanthanide‐Doped Nanoparticles

“…Due to their abundant energy levels, lanthanides have been doped in PLNPs to serve as the sensitizers or emitters to realize persistent emissions ranging from UV to NIR regions. In the past decade, different kinds of lanthanide‐doped PLNPs have been developed and their biomedical applications have been largely explored, such as in α‐fetoprotein and ascorbic acid detection as well as targeted tumor imaging . Moreover, vis‐to‐NIR or NIR‐to‐NIR lanthanide‐doped PLNPs that can be repeatedly charged in vivo have been developed for achievement of deep tissue and long‐term bioimaging .…”

“…Furthermore, with the recently developed “bottom‐up” strategies for controlled synthesis of PLNPs, well‐dispersed PLNPs with uniform size/shape and easy surface‐functionalization have been prepared, increasing the convenience of designing PLNPs probes with conjugated targeting molecules. In recent years, lanthanide‐doped PLNPs probes have been designed and their advantages in biosensing have been demonstrated …”

Portable Smartphone‐Based Platform for Real‐Time Particle Detection in Microfluidics

“…[5] Thus, the real-time detection of particles in microfluidics often requires a high-speed camera that can take a video with a high capture frame rate. [14][15][16][17] The smartphone camera also allows for multiple optical zooms that favor the image capture and analysis for mobile microscopy application. [6,7] As the smartphones are increasingly affordable with exponentially powerful processors, their usage for lab on a phone has emerged as an attractive option.…”