Aptamer-Functionalized Gold Nanoparticles as Probes in a Dry-Reagent Strip Biosensor for Protein Analysis

TLDR

The study develops a dry‑reagent lateral‑flow strip biosensor that couples aptamer‑functionalized gold nanoparticles with optical readout for rapid protein detection. The sensor uses a thrombin model with aptamer probes on a lateral‑flow strip, eliminating incubation and washing steps, and provides qualitative color change and quantitative optical signals via a portable strip reader. The biosensor displays a linear response from 5–100 nM thrombin with a 2.5 nM detection limit, matches or surpasses antibody‑based strips in specificity and sensitivity, and successfully detects thrombin in human plasma, indicating strong point‑of‑care potential.

Abstract

The highly specific molecular recognition properties of aptamers are combined with the unique optical properties of gold nanoparticles for the development of a dry-reagent strip biosensor that enables qualitative (visual)/quantitative detection of protein within minutes. A model system comprising thrombin as an analyte and a pair of aptamer probes is used to demonstrate the proof-of-concept on the conventional lateral flow test strip. The assay avoids the multiple incubation and washing steps performed in most current aptamer-based protein analyses. Although qualitative tests are realized by observing the color change of the test zone, quantitative data are obtained by recording the optical responses of the test zone with a portable "strip reader". The response of the biosensor is linear over the range of 5−100 nM of thrombin with a detection limit of 2.5 nM (S/N = 3). By comparing the analytical performances of the aptamer-based strip biosensor with the antibody-based strip sensor, we can demonstrate that aptamers are equivalent or superior to antibodies in terms of specificity and sensitivity, respectively. The sensor was used successfully for detection of thrombin in human plasma samples. It shows great promise for use of aptamer-functionalized gold nanoparticle probes in dry-reagent strip biosensors for point-of-care or in-field detection of proteins.