Molecularly imprinted polymer fluorescent spots (MIP@spots) for CA 19-9 detection on a solid substrate

Molecularly imprinted membranes were developed as a solid-support sensing platform for detecting the pancreatic cancer biomarker carbohydrate antigen 19-9 (CA 19-9) using a color-gradient method. Molecularly imprinted polymers (MIPs) were first synthesized around quantum dots (QDs) as colloidal MIP@QDs and subsequently integrated onto polyamide membranes (MIP@spots). This solid-support platform provided a stable and uniform surface for biorecognition, ensuring consistent performance and facilitating optical sensing. The MIP@spots effectively detected CA 19-9 in 1 % HN serum in PBS. Fluorescence quenching correlated with increasing CA 19-9 concentrations, producing a distinct color gradient measured using average RGB values from the MIP@spots' central areas via a mobile app. The system exhibited a linear detection range of 0.398–90.2 U mL −1 and achieved a limit of detection (LOD) of 0.141 U mL −1 , well below the clinical threshold of 37 U mL −1 . The polyamide membrane's porosity retained the MIP structure while preventing QDs agglomeration, enhancing sensitivity and reproducibility. This innovative platform offers a low-cost, highly sensitive, and specific tool for CA 19-9 detection. Its stability, simplicity, and compatibility with solid supports make it highly suitable for point-of-care testing (PoCT). This advancement highlights the potential of solid-support platforms in biosensing, paving the way for improved clinical diagnostics and personalized healthcare applications. • MIPs assembled around quantum dots form colloidal MIP@QDs were integrated onto polyamide membranes as MIP@spots. • MIP@spots effectively detect CA19-9 in 1 % HN serum, showing practical applicability. • Fluorescence quenching with increasing CA19-9 concentrations creates a clear colour gradient for visual quantification. • The system demonstrated a linear detection range of 0.398–90.2 U mL −1 and a limit of detection of 0.141 U mL −1 in serum.