Design of an innovative aptasensor for the detection of chemotherapeutic drug Fludarabine phosphate

Monitoring the concentration of Fludarabine phosphate, a standard chemotherapeutic drug widely used in cancer treatment, is vital for ensuring the drug's safety and effectiveness, tailoring treatments to individual needs, and consequently improving overall patient outcomes. Regarding the limitations of conventional techniques in terms of complexity, large time measurements, and a high cost, there is an urgent need to develop simple, rapid, and cost-effective devices. In this paper, we report the design of an aptasensor for the specific and selective detection of Fludarabine. Systematic evolution of ligands by exponential enrichment (SELEX) protocol was performed to select a specific aptamer for Fludarabine. Eleven rounds were carried out, and nine sequences were selected. Based on the dissociation constant (Kd), Ful-3, exhibiting the highest affinity (18.86 nM), was chosen and integrated into a simple electrochemical aptasensing platform for Fludarabine detection. Electrochemical results demonstrated good performance of the selected aptamer in detecting Fludarabine within the analytical range of 1 to 150 pg/mL and with LOD and LOQ in the order of 0.11 pg/mL (0.31 fM) and 0.39 pg/mL (1.06 fM), respectively. The developed platform also showed good selectivity against different analogous molecules and high applicability in serum-spiked samples, with recovery percentages ranging from 96.81 to 99.04%. Considering the encouraging results, this research presents an excellent alternative in terms of simplicity, stability, ease of use, reduction of sample volume, and low cost.