Label Free Detection of Programmed Death Ligand 1 Protein Biomarker by Quartz Tuning Fork-Based Biosensor

Abstract

Programmed death-ligand 1 (PD-L1) is expressed on the membrane of many types of cancer cells such as breast and lung cancer cells. PD-L1 helps the cancerous cells to escape the surveillance of the immune system. PD-L1 also exists in a soluble form, reaching detectable levels in cancer patient’s serum. The available detection techniques for PD-L1 are time and cost demanding, requiring advance instrumentations and efforts. To overcome the challenges of the current detection techniques, functionalized quartz tuning forks are employed as biosensors for the real-time detection of PD-L1. In this study, the QTF gold coated biosensors have been functionalized by Anti PD-L1 monoclonal antibodies as a probe layer. The functionalized QTF biosensors were tested against different concentrations of PD-L1 protein ranging from 0.05 up to 500 ng ml−1, with an incubation time of 15 min. It has been observed that the QTF resonance frequency shifted correlatively with the PD-L1 concentration. Testing of other proteins has not shown significant responses indicating the suitability of the probe layer’s selectivity for PD-L1. This result is expected to open the way for a fast and early yet simple approach for the possible discovery of cancer cells in initial stages, and cancer treatment monitoring.