Dual-aptamer system for magnetic isolation and flow cytometry detection of PD-L1 positive cells in serum samples
Microchemical Journal, cilt.225, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 225
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.microc.2026.118032
- Dergi Adı: Microchemical Journal
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Chemical Abstracts Core, Chimica, Index Islamicus
- Anahtar Kelimeler: Aptasensor, Flow cytometry, Liquid biopsy, PD-L1, SELEX
- İstanbul Üniversitesi-Cerrahpaşa Adresli: Evet
Özet
Programmed death-ligand 1 (PD-L1) is a critical immune checkpoint protein often upregulated in cancer cells to evade immune surveillance. The accurate quantification of cell-surface PD-L1 is essential for predicting patient response to immune checkpoint blockade therapies. This study reports the development of a highly sensitive flow cytometry assay utilizing a dual-aptamer strategy for the isolation and quantification of PD-L1+ cells in serum. DNA aptamers targeting the extracellular domain of PD-L1 were selected via Systematic Evolution of Ligands by EXponential Enrichment (SELEX). Two candidate sequences, AptPDL1-S1 and AptPDL1-S2, were identified with high binding affinities (Kd of 270.3 ± 14.4 nM and 542.1 ± 95.4 nM, respectively). To analyze serum samples, AptPDL1-S2 was conjugated to magnetic microparticles for the specific enrichment of target cells, followed by labeling with fluorescein-conjugated AptPDL1-S1 for flow cytometric detection. The assay successfully discriminated between high-expressing BT20 cells and low-expressing MCF-7 cells. The method achieved a Limit of Detection (LOD) 273 cells/mL, demonstrating its potential as an antibody-free alternative for liquid biopsy applications in precision oncology.