Construction of Electrochemical Aptamer Sensor Based on Pt-Coordinated Titanium-Based Porphyrin MOF for Thrombin Detection

In this work, a Pt-coordinated titanium-based porphyrin metal organic framework (Ti-MOF-Pt) was prepared by embedding single-atom Pt through strong interactions between the four pyrrole nitrogen atoms in the rigid backbone of the porphyrin. The synthesized Ti-MOF-Pt was characterized by TEM, XRD, FTIR and BET. Then, the Ti-MOF-Pt has been used for glassy carbon electrode surface modification and consequently used for construction of a thrombin aptamer sensor. The high surface area provides by MOF and excellent electrochemical property provided by Pt enhance the sensing performance. After optimization of amount of aptamer, hybridization time and specific reaction time, the fabricated aptamer sensor exhibited a linear relationship with the logarithm of the thrombin concentration in the range of 4 pM to 0.2 μM. The detection limit can be calculated as 1.3 pM.

New Aptamer/MoS2/Ni-Fe LDH Photoelectric Sensor for Bisphenol A Determination

Here, a new type of PEC aptamer sensor for bisphenol A (BPA) detection was developed, in which visible-light active MoS2/Ni-Fe LDH (layered double hydroxide) heterostructure and aptamer were used as photosensitive materials and biometric elements, respectively. The combination of an appropriate amount of MoS2 and Ni-Fe LDH enhances the photocurrent response, thereby promoting the construction of the PEC sensor. Therefore, we used a simple in situ growth method to fabricate a MoS2/Ni-Fe LDH sensor to detect the BPA content. The aptasensor based on aptamer/MoS2/Ni-Fe LDH displayed a linear range toward a BPA of 0.05–10 to 50–40,000 ng L−1, and it has excellent stability, selectivity and reproducibility. In addition, the proposed aptamer sensor is effective in evaluating real water samples, indicating that it has great potential for detecting BPA in real samples.

A Significant Fluorescent Aptamer Sensor Based on Carbon Dots and Graphene Oxide for Highly Selective Detection of Progesterone

In this paper, a fluorescent aptamer sensor was constructed based on the carbon dots and graphene oxide. This sensor combines the excellent fluorescence performance of carbon dots with the high specificity of aptamers to detect progesterone with high sensitivity and selectivity. In the absence of progesterone, the carbon dots-aptamer system and graphene oxide form a fluorescence resonance energy transfer process(FRET), which quenches the fluorescence of the carbon dots. When progesterone is added, the aptamer specifically binds to progesterone, resulting the fluorescence of the carbon dots is recovered. At optimal conditions, the fluorescence intensity recovered by the carbon dots has a linear relationship with the concentration of progesterone in the range of 0.1-120 nM, and the detection limit is 3.3×10 -11 M. Besides, the sensor has satisfactory detection results of progesterone in milk, indicating that this method has a enormous potential for application in food safety.

A Novel Photoelectrochemical Aptamer Sensor Based on CdTe Quantum Dots Enhancement and Exonuclease I-Assisted Signal Amplification for Listeria monocytogenes Detection

To achieve the rapid detection of Listeria monocytogenes, this study used aptamers for the original identification and built a photoelectrochemical aptamer sensor using exonuclease-assisted amplification. Tungsten trioxide (WO3) was used as a photosensitive material, was modified with gold nanoparticles to immobilize complementary DNA, and amplified the signal by means of the sensitization effect of CdTe quantum dots and the shearing effect of Exonuclease I (Exo I) to achieve high-sensitivity detection. This strategy had a detection limit of 45 CFU/mL in the concentration range of 1.3 × 101–1.3 × 107 CFU/mL. The construction strategy provides a new way to detect Listeria monocytogenes.

Novel DNA Aptameric Sensors to Detect the Toxic Insecticide Fenitrothion

Fenitrothion is an insecticide belonging to the organophosphate family of pesticides that is widely used around the world in agriculture and living environments. Today, it is one of the most hazardous chemicals that causes severe environmental pollution. However, detection of fenitrothion residues in the environment is considered a significant challenge due to the small molecule nature of the insecticide and lack of molecular recognition elements that can detect it with high specificity. We performed in vitro selection experiments using the SELEX process to isolate the DNA aptamers that can bind to fenitrothion. We found that newly discovered DNA aptamers have a strong ability to distinguish fenitrothion from other organophosphate insecticides (non-specific targets). Furthermore, we identified a fenitrothion-specific aptamer; FenA2, that can interact with Thioflavin T (ThT) to produce a label-free detection mode with a Kd of 33.57 nM (9.30 ppb) and LOD of 14 nM (3.88 ppb). Additionally, the FenA2 aptamer exhibited very low cross-reactivity with non-specific targets. This is the first report showing an aptamer sensor with a G4-quadruplex-like structure to detect fenitrothion. Moreover, these aptamers have the potential to be further developed into analytical tools for real-time detection of fenitrothion from a wide range of samples.

A Simple and Sensitive Nanogold RRS/Abs Dimode Sensor for Trace As3+ Based on Aptamer Controlled Nitrogen Doped Carbon Dot Catalytic Amplification

Using citric acid (CA) and ethylenediamine (EDA) as precursors, stable nitrogen-doped carbon dots (CD) nanosols were prepared by microwave procedure and characterized in detail. It was found that CDNs catalyze ethanol (Et)-HAuCl4 to generate gold nanoparticles (AuNPs), which have strong surface plasmon resonance, Rayleigh scattering, (RRS) and a surface plasmon resonance (SPR) absorption (Abs) effect at 370 nm and 575 nm, respectively. Compled the new catalytic amplification indicator reaction with the specific As3+ aptamer reaction, a new RRS/Abs dual-mode aptamer sensor for the assay of trace As3+ was developed, based on the RRS/Abs signals increasing linearly with As3+ increasing in the ranges of 5–250 nmol/L and 50−250 nmol/L, whose detection limits were 0.8 nmol/L and 3.4 nmol/L As3+, respectively. This analytical method has the advantages of high selectivity, simplicity, and rapidity, and it has been successfully applied to the detection of practical samples.