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Paper-based lateral flow assays, though being lowcost and widely used for rapid in vitro diagnostics, are indicative and do not provide sufficient sensitivity for the detection and quantification of low abundant biomarkers for early stage cancer diagnosis. Here, we design a compact device to create a focused illumination spot with high irradiance, which activates a range of highly doped 50 nm upconversion nanoparticles (UCNPs) to produce orders of magnitude brighter emissions. The device employs a very low-cost laser diode, simplified excitation, and collection optics and permits a mobile phone camera to record the results. Using highly erbium ion (Er 3+ )-doped and thulium ion (Tm 3+ )-doped UCNPs as two independent reporters on two-color lateral flow strips, new records of limit of detection (LOD), 89 and 400 pg/mL, have been achieved for the ultrasensitive detection of prostate specific antigen (PSA) and ephrin type-A receptor 2 (EphA2) biomarkers, respectively, without crosstalk. The technique and device presented in this work suggests a broad scope of low-cost, rapid, and quantitative lateral flow assays in early detection of bioanalytes.

The surface plasmon resonance (SPR) sensor is an important tool widely used for studying binding kinetics between biomolecular species. The SPR approach offers unique advantages in light of its real-time and label-free sensing capabilities. Until now, nearly all established SPR instrumentation schemes are based on single- or several-channel configurations. With the emergence of drug screening and investigation of biomolecular interactions on a massive scale these days for finding more effective treatments of diseases, there is a growing demand for the development of high-throughput 2-D SPR sensor arrays based on imaging. The so-called SPR imaging (SPRi) approach has been explored intensively in recent years. This review aims to provide an up-to-date and concise summary of recent advances in SPRi. The specific focuses are on practical instrumentation designs and their respective biosensing applications in relation to molecular sensing, healthcare testing, and environmental screening.

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Novel 3D barcodes with an extraordinarily high encoding capacity are developed through a flexible, accurate, and reproducible method. Here, the three dimensions refer to the size, fluorescence emission wavelength, and intensity of the barcodes. As a proof of concept, a 3D barcode library with an encoding capacity of 100 flow cytometry-distinguishable barcodes is achieved successfully by combining the multiscaled host particles with a set of guest nanoparticles owning to their individual different fluorescent intensity via an ingenious host–guest structure, where fluorescein isothiocyanate and a kind of quantum dots are separately loaded inside. Five-plexed tumor marker detection is further implemented, and the results demonstrate the strong feasibility of 3D barcodes in multiplex assays.