Colloidal gold immunochromatography has emerged as a pivotal platform for point-of-care diagnostics, yet challenges persist in stabilizing nanoparticle-antibody interactions and ensuring batch-to-batch reproducibility. To address these limitations, we engineered a nanogold-affinity peptide probe for the rapid detection of the lung cancer biomarker carcinoembryonic antigen (CEA), leveraging phage-display-derived peptides as biorecognition elements. The probe was synthesized by conjugating CEA-specific affinity peptides to polyethylene glycol (PEG)-functionalized gold nanoparticles (AuNPs) via covalent amide bonding, ensuring precise orientation and enhanced colloidal stability. Systematic optimization of reaction parameters, including the PEGylation time, peptide-to-nanoparticle ratios, and centrifugation conditions, yielded a robust preparation protocol. The resulting immunochromatographic test strip demonstrated a detection limit of 2.5 ng/mL for CEA, surpassing the clinical threshold of 5 ng/mL, and exhibited 91.7% accuracy in clinical serum samples. Notably, the substitution of antibodies with synthetic affinity peptides reduced costs by approximately 8-fold while maintaining high specificity and resistance to nonspecific binding. This work not only advances the integration of biomolecular engineering and nanotechnology for diagnostic applications but also establishes a scalable framework for developing stable, low-cost biosensors targeting macromolecular biomarkers.

The quantitative analysis of nucleic acid markers is extensively utilized in cancer detection. However, it faces significant challenges, such as the need for specialized detection devices and the inherent complexity of testing procedures. To address these issues, this study proposes a simplified, rapid, and user-friendly platform for cancer nucleic acid marker detection. We firstly designed a polydimethylsiloxane (PDMS) device for the isothermal amplification reaction of nucleic acid biomarkers based on reverse-transcription recombinase-aided amplification (RT-RAA) technology. Specifically, three potential cancer nucleic acid biomarkers, carcinoembryonic antigen (CEA), prostate-specific antigen (PSA), and prostate cancer antigen 3 (PCA3) were amplified from human serum or urine samples in the PDMS device at body temperature. The reaction chamber was directly integrated with nucleic acid test strips labeled with colloidal gold nanoparticles, allowing for the visual observation of the detection results for the amplification products. The optimal reaction conditions, such as pH, reaction time, antibody, and streptavidin concentration, were defined after a series of optimization studies. The findings demonstrated that the optimal RT-RAA reaction time was 20 min, the primary antibodies were labeled with colloidal gold to the greatest extent at pH 8.5, and the optimal concentrations of secondary antibody and streptavidin were 1.0 mg/mL and 0.5 mg/mL, respectively. Furthermore, this novel detection approach could not only exhibit excellent sensitivity and specificity but also show high accuracy for the analysis of nucleic acid biomarkers in both clinical serum and urine samples. Therefore, the simplified and more convenient operation platform provides a new insight for the semi-quantitative analysis of cancer nucleic acid biomarkers and the rapid screening of early cancer, thereby offering a promising alternative to oncological point-of-care testing (POCT) diagnostics.

Small cell lung cancer (SCLC) is one of the most aggressive malignancies, with early detection being crucial for improving patient outcomes. Serum biomarke

Non-small cell lung cancer (NSCLC) is the predominant form of lung cancer and poses a significant public health challenge. Early detection is crucial for improving patient outcomes, with serum biomarkers such as carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCCAg), and cytokeratin fragment 19 (CYFRA 21-1) playing a critical role in early screening and pathological classification of NSCLC. However, due to being mainly based on corresponding antibody binding reactions, existing detection technologies for these serum biomarkers have shortcomings such as complex operations, high false positive rates, and high costs. This study aimed to develop new methods for detecting CEA, SCCAg, and CYFRA 21-1 to assist in the diagnosis of NSCLC. Affinity peptides of CEA, SCCAg, and CYFRA 21-1, respectively, were screened by phage display technology, and the peptides’ binding affinities were determined by enzyme-linked immunosorbent assay and biolayer interferometry. Peptides with high affinity were then integrated as binding domains into biosensors by fusing them with circularly permuted fluorescent proteins (cpFPs) through genetic coding. The resulting biosensors, C4 biosensor for CEA, S1 biosensor for SCCAg, and Y3 biosensor for CYFRA 21-1, demonstrated robust sensitivity and specificity even at concentrations as low as 1 ng/mL for their respective tumor markers. When applied to clinical samples and recalibrated for the upper limit of normal concentrations, the biosensors exhibited enhanced sensitivity and specificity for NSCLC diagnosis. This study introduced innovative biosensors for the detection of CEA, SCCAg, and CYFRA 21-1, providing a highly sensitive, specific, rapid, and cost-effective diagnostic alternative that could significantly improve NSCLC screening rates.