Lateral Flow Immunoassays – from Paper Strip to Smartphone Technology

Abstract

Cyclic peptides are important natural products and hold great promise for the identification of new bioactive molecules. The split‐intein‐mediated SICLOPPS technology provides a generic access to fully genetically encoded head‐to‐tail cyclized peptides and large libraries thereof (SICLOPPS=split‐intein circular ligation of peptides and proteins). However, owing to the spontaneous protein splicing reaction, product formation occurs inside cells, making peptide isolation inconvenient and precluding traditional in vitro assays for inhibitor discovery. The design of a genetically encoded, light‐dependent intein using the photocaged tyrosine derivative ortho‐nitrobenzyltyrosine incorporated at an internal, non‐catalytic position is now reported. Stable intein precursors were purified from the E. coli expression host and subsequently subjected to light activation in vitro for both the regular protein splicing format and cyclic peptide production, including the natural product segetalin H as an example. The activity of the intein could also be triggered in living cells.

Lateral and Vertical Flow Assays for Point‐of‐Care Diagnostics

“…A smartphone with a high‐resolution rear camera that could be used as a POC reader for optical detection, including colorimetry, fluorescence, luminescence, has become an emerging readout platform for LFA POC diagnostics . The number of smartphone users is expected to reach 2.5 billion in 2019, with a projected 36% of the world's population currently using a smartphone, up from 10% in 2011 .…”

“…Current smartphones have real‐time geotagging and secure cloud computing. This provides an opportunity for highly sensitive devices that use colorimetric analysis to detect low light and deliver quantitative results …”

Sensitivity enhancement in lateral flow assays: a systems perspective

“…44 In addition, to reduce reader-associated test costs, particularly for low-resource settings, recent research has been conducted on the use of smartphones as LFA readers. [45][46][47] Near-infrared (NIR) fluorescent dyes were reported to allow the sensitivity of IL-6 and C-reactive protein LFAs to match that of traditional ELISAs. Additionally, as these dyes absorb and emit fluorescence at wavelengths outside of typical biological matrices, these results were obtained for analytes spiked into 10% plasma matrices.…”

Methods for the Diagnosis of Grapevine Viral Infections: A Review

“…The intensity of coloration in the binding zones is registered for this purpose and compared with values from a calibration curve. The existing devices (including commercially available ones) and software for such registration in LFIA of different compounds are considered in [65][66][67].…”