Rapid, point‑of‑care treponemal tests are essential for interrupting Treponema pallidum transmission, yet published evaluations show that commercial assays still leave a sensitivity gap of ~1–5 percentage points and occasional hook‑effects at high antibody titres. To close that gap we engineered a new assay around Axiflow’s lateral‑flow architecture, pairing the company’s high‑performance membrane and pad portfolio with Micronic’s chimeric TP15 + TP17 + TP47 antigens.
Materials & Strip Architecture
| Functional Layer | Axiflow Part | Key Attribute for Sensitivity |
| Nitrocellulose membrane | AXC100‑CH25 | 100 µm thickness, ~100 s/4 cm capillary time → optimized antigen–antibody residence |
| Conjugate pad | 16613N-T01 (Polyester) | Uniform release of AuNP–antigen conjugate (6-8 OD) |
| Sample pad | 16615‑T05 (Polyester) | Pre‑conditioned for serum / plasma / WB pH 7.4 ± 0.2 |
| Blood separator | PSP60+ (Fiber blend) | 95 % RBC retention, <10 s separation time |
| Absorbent pad | 1222N (Cellulose) | 45 µL cm⁻¹ capacity prevents early flow arrest |
| Backing card | BPC060300 PVC | 300 µm rigidity for automated lamination |
Performance Highlights
· Analytical LoD: 0.5 IU mL⁻¹ anti‑TP (in‑house panel, n = 25), a four‑fold improvement over a market‑leading treponemal card test run in parallel.
·Clinical sensitivity/specificity: 99.1% / 100.0% versus TPHA ± VDRL (n =400 serum & whole‑blood specimens).
Read‑time: Visible signal within 12 min; official read window 15–20 min.
·Robust matrix tolerance of PSP60+: Consistent T/C ratios with whole blood haematocrits from 35 % to 55 %.
Key Takeaways for Assay Developers
· Membrane kinetics matter: A 100-sec. membrane strikes an optimal balance between binding residency and total run‑time for IgG/IgM treponemal targets.
· Matrix‑matched pad chemistry: Pre‑treated sample and conjugate pads reduce hook effects and lot‑to‑lot drift.
· Integrated blood separation: PSP60+ enables a true whole‑blood format without external devices, widening POC usability.
·Scalable workflow: All components are supplied in reel format and are compatible with standard automated striping, drying, and lamination lines, ensuring seamless tech‑transfer into volume manufacturing.
Outcome
Leveraging Axiflow’s integrated material set enabled us to deliver a syphilis antibody LFA that meets desired regulatory & market benchmarks for treponemal diagnostics while providing faster time‑to‑result and superior analytical depth.