1：Experimental Design and Method Selection:

The platform integrates a lateral flow assay (LFA) detection system using upconversion nanoparticles (UCNPs), a miniaturized reader with an infrared laser and optical components, and a smartphone app for real-time analysis. The design focuses on portability, multiplexed detection, and quantitative analysis.

2：Sample Selection and Data Sources:

Targets include nucleic acid (hepatitis B virus, HBV), protein (growth stimulation expressed gene 2, ST-2), small molecule (ochratoxin A, OTA), heavy metal ion (Hg2+), and bacteria (salmonella, SE). Samples were prepared and tested using UCNP-LFAs.

3：List of Experimental Equipment and Materials:

Equipment includes a UCNP-LFA reader with laser diode, dichroic mirror, infrared filter, smartphone, and various materials for UCNP synthesis and LFA fabrication (e.g., chemicals from Sigma-Aldrich, Alfa Aesar, and others).

4：Experimental Procedures and Operational Workflow:

UCNPs were synthesized via thermal decomposition, surface-modified with PAA, and conjugated to DNA or antibodies. UCNP-LFAs were fabricated by assembling pads and dispensing probes. Detection involved adding samples to LFAs, inserting strips into the reader, capturing images with a smartphone, and analyzing with the custom app.

5：Data Analysis Methods:

The app extracts RGB values from images, calculates signal differences between test lines and background, and uses calibration curves for quantitative analysis. Correlation with gold-standard methods (e.g., NIR-CW-laser and computer software) was performed.