Jiangxiong Zhu,Yang Wang,Lumei Wang,Xueqing Geng,Linnan Yang,Ting Zhao,Yun Deng
ObjectiveThe objective of this study is to develop a novel fluorometric aptasensor employing fluorescence resonance energy transfer (FRET) for the detection of Cadmium (II) (Cd2+) in water and food samples. The constructed aptasensor employed a fluorophore-quencher labeled aptamer combination not previously reported for Cd2+ detection. Additionally, its simple mix-and-detect pattern without immobilization or material-assisted steps represented an innovative design.MethodsUtilizing 6-carboxyfluorescein (FAM)-modified aptamers and maleimide (BHQ-1)-modified aptamer complementary chain to construct a fluorescent detection probe, this aptasensor achieved a rapid, sensitive, and selective detection of Cd2+. Without Cd2+, the aptamer and its complementary strand undergo base pairing, bringing the FAM closer to the BHQ-1, and leading to FRET and a subsequent decrease in fluorescence intensity. The introduction of Cd2+ preferentially brought to the aptamer, changing its conformation and preventing the quenching of FAM by BHQ-1, thereby restoring the fluorescence intensity of the aptasensor.ResultsFollowing optimization of experimental parameters, the aptasensor exhibited a linear response to Cd2+ concentrations ranging from 5 to 1200 nM, with a detection limit (LOD) of 0.43 nM. The aptasensor’s performance was unaffected by the presence of various ions, indicating its high specificity. Moreover, it could rapidly and accurately detect Cd2+ in water and food samples, including tap water, lake water, grapes, cabbage, and broccoli, demonstrating its substantial potential for practical application.ConclusionTherefore, the developed aptasensor represents an important tool for effective Cd2+ detection in water and food matrices, highlighting its potential as a critical tool for environmental monitoring and food safety.
In situ monitoring of intracellular microRNAs (miRNAs) often encounters the challenges of surrounding complexity, coexistence of precursor miRNAs (pre-miRNAs) and the degradation of biological enzyme in living cells. Here, we designed a novel probe encapsulated DNA tetrahedral molecular sieve (DTMS) to realize the size-selective detection of intracellular miRNA 21 that can avoid the interference of pre-miRNAs. In such strategy, quencher (BHQ-1) labeled probe DNA (S6-BHQ 1) was introduced into the inner cavity of fluorophore (FAM) labeled DNA tetrahedral scaffolds (DTS) to prepare DTMS, making the FAM and BHQ-1 closely proximate, and resulting the sensor in a "signal-off" state. In the presence of miRNA 21, strand displacement reaction happened to form more stable DNA double-stranded structure, accompanied by the release of S6-BHQ 1 from the inner cavity of DTMS, making the sensor in a "signal-on" state. The DTMS based sensing platform can then realized the size-selective detection of miRNA 21 with a detection limit of 3.6 pM. Relying on the mechanical rigidity of DTS and the encapsulation of DNA probe using DTMS, such proposed method achieved preferable reproducibility and storage stability. Moreover, this sensing system exhibited good performance for monitoring the change of intracellular miRNA 21 level during the treatment with miRNA-related drugs, demonstrating great potential for biological studies and accurate disease diagnosis.
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