Title: A Natural-Material-Assisted Calibration Strategy Coupled with Indirect Optical Detection of Radon Decay Products
Authors: Ayad Hussein Resenč, Basim A. AlmayahiČ
Volume: 10
Issue: 5
Pages: 53-57
Publication Date: 2026/05/28
Abstract:
Calibrating radon detection equipment typically relies on heavily regulated, synthetic radioactive sources. This study introduces a practical, low-risk alternative: utilizing natural building materials-specifically granite and regional soils-as continuous radon-emanating matrices for system calibration. To validate this natural calibration approach, we developed an indirect optical biosensing platform based on guanine-rich DNA aptamers. Because radon is a chemically inert noble gas, direct aptamer binding is mechanistically implausible. Instead, our system targets the lead ions (PbČ?) generated through the radon decay chain. Following an 8-day vacuum extraction period, the preconcentrated PbČ? induces the aptamer to fold into a G-quadruplex structure, which enhances the fluorescence of malachite green. We evaluated 17 samples, including granite, ceramic, and soil. The biosensor demonstrated promising analytical sensitivity, achieving theoretical detection limits of 1 Bq/mł for radon equivalents and 4 nM for lead, with a rapid 5-minute fluorescence readout post-extraction. Compared to conventional RAD7 and CR-39 detectors, the biosensor showed higher analytical sensitivity under controlled laboratory extraction conditions and exhibited robust performance independent of ambient temperature and humidity fluctuations. These results suggest that natural calibration matrices, combined with indirect PbČ? aptamer sensing, represent a potential candidate for routine environmental monitoring.