Technical Support

Principle: WWHS uses fluorescent microspheres with an emission wavelength in the near-infrared II region (NIR-II, >1000 nm) as signal labels, conjugated with specific antibodies to build an immunoassay system. During testing, the target analyte in the sample undergoes a specific immune reaction with the NIR-II fluorescent-microsphere-labeled antibody, forming a quantifiable fluorescent signal on the test cassette. The dedicated analyzer (NIR-1000) captures the fluorescence intensity in the NIR-II band and, using a pre-established standard curve, converts the fluorescence signal into a quantitative result for the analyte. This method is essentially a combination of immunochromatographic testing and NIR-II optical detection; by selecting a better optical window, it improves the signal-to-noise ratio and quantitative stability.

Advantages:

• A. Significantly reduced background interference and higher SNR: In the NIR-II band, absorption, scattering, and autofluorescence of common biological matrices (hemoglobin, lipids, bilirubin, etc.) are greatly reduced; compared with visible-light and NIR-I fluorescent labels, background noise is lower, yielding a higher signal-to-noise ratio (SNR).
• B. Higher detection sensitivity for low-concentration quantification: Under low-background conditions, the effective signal of NIR-II fluorescent microspheres is easier to distinguish and amplify, enabling immunoassay sensitivity close to chemiluminescence methods without magnetic-bead separation or complex washing steps.
• C. Better quantitative stability and higher reproducibility: The NIR-II band is less affected by ambient light, and the detection signal is less sensitive to sample color, mild hemolysis, or lipemia, helping improve within-run and between-run reproducibility and enhancing the stability and consistency of quantitative detection.
• D. High performance combined with simple operation: The detection workflow retains the simple operation and rapid reaction advantages of immunochromatography.
• E. A foundation for multi-analyte expansion and platform-based testing: NIR-II fluorescent microspheres offer good optical tunability and batch consistency, enabling standardized and scalable quantitative testing for different analytes on the same platform.

Mainly in vivo imaging. Angiography, cerebral vascular imaging, tumor boundary delineation and surgical navigation, sentinel lymph node mapping, stem cell and immune cell tracking, and drug distribution and metabolism are the most active NIR-II fields. In small-animal tests, transmittance exceeds 92% in the 850–1650 nm band, resolution reaches the 10-micron level, and acquisition can reach 2000 frames per second. Sub-windows such as NIR-IIb (1500–1700 nm) have lower scattering and higher SNR.

Professor Hongjie Dai's group first achieved sub-micron near-infrared in vivo imaging in Nature Nanotechnology in 2009, laying the foundation for the later NIR-II (1000–1700 nm) window. For more than a decade afterward, work focused mainly on in vivo imaging and materials research. Co-integrating the light source, nanospheres, and detector, and then completing stability validation and registration, takes a very long time — one reason NIR-II has long stayed in the laboratory with few finished products.

The NIR-1000 is a dry fluorescence immunoassay analyzer based on near-infrared II (NIR-II) fluorescence. Positioned for primary-care POCT, it covers three scenarios: chest-pain centers and emergency departments in tiered hospitals, county-level medical communities, and private clinics. The design trade-offs are clear — as easy to operate as colloidal gold, while delivering reliable quantitative results at a cost primary care can afford.