Fast Amplification and Spectral‑coded Tags for Strip‑based Target Readout with Intelligent Processing (FAST‑STRIP)

The COVID‑19 pandemic underscored that the most impactful diagnostics were PCR‑based molecular tests and LFIA rapid antigen assays. PCR offers near‑gold‑standard analytical sensitivity but is slow (≈1 h per run) and typically centralized, which during surges translated into multi‑day delays. LFIAs, by contrast, are agile, low‑cost, and home‑care ready, yet often fall short of clinical sensitivity. Although ultra‑rapid thermocyclers now complete ~30 cycles in minutes, the readout remains the bottleneck: gel‑based end‑point analysis is labor‑intensive, while real‑time fluorescence—especially on fast platforms—drives up instrument and reagent costs.

We propose an integrated platform that repurposes materials from oncology nanomedicine to couple ultra‑fast PCR with lateral‑flow end‑point detection, purpose‑built for ultra‑fast and sustainable use in PoC settings. The design preserves the multiplexing strengths of end‑point PCR while approaching the quantitative performance of real‑time assays. Three elements are central. (i) A universal strip concept enabled by tagged primers (e.g., a poly(A) handle on the forward primer and a capture tag such as biotin on the reverse), so that a single conjugate and capture architecture can service many targets with minimal re‑engineering. (ii) Multicolor plasmonic labels (e.g., gold nanorods with distinct aspect ratios) providing orthogonal spectral codes across multiple test lines and colors, enabling high‑order multiplexing and internal process controls within the same strip. (iii) Machine‑learning‑assisted imaging (smartphone or compact reader) that converts multi‑line, multi‑color intensity patterns into calibrated, copy‑number–like outputs, compensating for matrix effects and lot variation.

The workflow is compatible with rapid extraction protocols, closed‑cartridge operation (with dUTP/UNG carry‑over control), and aims for sample‑to‑answer in <15 min with a per‑test bill‑of‑materials suitable for decentralized screening. In our laboratories the full pipeline is already functional, with a current TRL ≈ 4; near‑term milestones include analytical LoD benchmarking vs. RT‑qPCR, prospective clinical concordance studies, and ruggedization for field deployment.