Magneto-fluorescent nanobiosensor with tetrahedral framework nucleic acid-confined aptamer for trace adenosine triphosphate detection

Accurate quantitation of trace-level ATP biomarkers often suffers from interference of sample matrix and remains a challenge. Herein, a novel magnetic biological nanosensor (MBNS) integrating tetrahedral framework nucleic acid (tFNA)-confined aptamers and ultrasensitive laser-induced fluorescence (LIF) was tailored and evaluated. The fluorescent aptamer nanoprobe hybridized with FAM-labelled cDNA was particularly incorporated into the inner cavity of tFNA, enabling a dual-mode mechanism that integrates molecular size selection and aptamer affinity recognition. By this strategy, the benefits of tFNA molecular sieve, the super sensitive properties of LIF, and the specific recognition of "aptamer gene codes" were integrated, as triggered the superior response of ATP. The structures, properties and reaction mechanism of tFNA, as well as tFNA modified with aptamer probe at different sites, were characterized in detail. A high level of anti-interference was achieved, shielding against non-specific adsorption even in matrices with high protein and analogue content, 103∼105 times higher than ATP. The release of fluorescent beacon from aptamer probe was facilely driven by specific binding of ATP, and an ultra-sensitive detection of 75 pmol/L ATP was obtained without amplification. It was 2–3 orders of magnitude more sensitive than most fluorescent aptasensors. Applied to serum samples, the stability and reproducibility of the resultant aptasensor have been validated with the intra- and inter-assay RSD in 1.6–6.4 % and -1.5–8.4 %, respectively. Acceptable recoveries of 96.5–106.8 % were achieved, consistent with the LC-MS method. It was expected to open a simple and efficient protocol for highly specific and ultrasensitive ATP detection in clinical diagnostics.