Highly sensitive and portable aptasensor by using enzymatic nanoreactors as labels

Due to the extremely low concentration of many small molecular targets, improving the sensitivity of aptasensors is urgently needed. Herein, a highly sensitive and portable biosensing platform of Fe₃O₄@Au-Apt/DMSNs-I-cDNA is designed on magnetic Fe₃O₄@Au by using enzymatic nanoreactors as signal labels. This signal label is prepared by encapsulating invertase into dendritic mesoporous silica nanoparticles (DMSNs-I), resulting in large enzyme load amount (407.3 ± 28 mg g⁻¹) and high bioactivity recovery (78.56%). Therefore, DMSNs-I can efficiently convert sucrose into glucose with personal glucose meter (PGM) as readout. Under PGM assay mode, this sensing platform achieves accurate recognition and sensitive detection of aflatoxin B1 (AFB1) and bisphenol A (BPA) with low detection limits of 0.74 pg mL⁻¹ and 0.094 pM (S/N = 3), respectively. Compared with the single invertase labelled aptasensor, the DMSNs-I labelled AFB1 aptasensor achieves ~3.19 times enhancement of sensitivity and 2 orders of magnitude lower in the detection limit. In addition, the proposed aptasensors are applied to detect AFB1 and BPA in complex samples with the acceptable recovery values. They also exhibited good selectivity and high stability, indicating the potential of the Fe₃O₄@Au-Apt/DMSNs-I-cDNA biosensing platform in constructing highly sensitive aptasensors for detecting small molecules.