Development of a Lateral Flow Strip with a Positive Readout for the On-Site Detection of Aflatoxin B1.

Aflatoxin B1 is one of the contamination indicators for food safety monitoring. The rapid and effective assessment and determination of AFB1 in food is of great importance to dietary safety. The lateral flow assay shows advantages in its simplicity, and rapidity, and provides a visual readout, while the available lateral flow assay for AFB1 requires a competitive format that produces readings inversely proportional to the AFB1 concentration, which is counterintuitive and may lead to a potential misinterpretation of the results. Herein, we developed a positive readout aptamer-based lateral flow strip (Apt-strip) for the detection of AFB1. This Apt-strip relies on the competition between AFB1 and fluorescein-labeled complementary DNA strands (FAM-cDNA) for affinity binding to limited aptamers against AFB1 (AFB1-Apt). In the absence of AFB1, AFB1-Apt hybridizes with FAM-cDNA. No signal at the T-line of the Apt-strip was observed. In contrast, AFB1-Apt binds to AFB1 in the sample, and then a part of the FAM-cDNA is hybridized with the free AFB1-Apt, at which time the other unreacted FAM-cDNA is captured by A35-Apt on the T-line. The signal was observed. This method achieved fast detection of AFB1 with a detection limit (DL) of 0.1 ng/mL, positive readout, and increased sensitivity.

Discovery of Novel 2,4-Dianilinopyrimidine Derivatives Containing 4-(Morpholinomethyl)phenyl and N-Substituted Benzamides as Potential FAK Inhibitors and Anticancer Agents.

Focal adhesion kinase (FAK) is responsible for the development and progression of various malignancies. With the aim to explore novel FAK inhibitors as anticancer agents, a series of 2,4-dianilinopyrimidine derivatives 8a-8i and 9a-9g containing 4-(morpholinomethyl)phenyl and N-substituted benzamides have been designed and synthesized. Among them, compound 8a displayed potent anti-FAK activity (IC50 = 0.047 ± 0.006 µM) and selective antiproliferative effects against H1975 (IC50 = 0.044 ± 0.011 µM) and A431 cells (IC50 = 0.119 ± 0.036 µM). Furthermore, compound 8a also induced apoptosis in a dose-dependent manner, arresting the cells in S/G2 phase and inhibiting the migration of H1975 cells, all of which were superior to those of TAE226. The docking analysis of compound 8a was performed to elucidate its possible binding modes with FAK. These results established 8a as our lead compound to be further investigated as a potential FAK inhibitor and anticancer agent.

Aptamer based surface plasma resonance assay for direct detection of neuron specific enolase and progastrin-releasing peptide (31-98).

Neuron specific enolase (NSE) and progastrin-releasing peptide (31-98) (ProGRP31-98) are considered as reliable biomarkers of small cell lung cancer (SCLC). Sensitive determinations of NSE and ProGRP31-98 show great significance in disease surveillance, clinical diagnosis, efficacy evaluation and prognostic judgment. However, the conventional detection methods have the disadvantages of poor stability, tedious operation, and being very time consuming. Herein, we developed an aptamer-based surface plasmon resonance (SPR) assay in a direct format for NSE and ProGRP31-98 detection. The aptamer was loaded on a sensor chip and used as an affinity ligand. With sample injection, SPR signals increased due to the association of the target to the aptamer coated chip. Further dissociation and regeneration allowed this aptamer sensor chip to be used for the next sample analysis. We achieved sensitive detection of NSE and ProGRP31-98 by measuring the affinity binding-induced SPR responses. The detection limits for NSE and ProGRP31-98 were 3.9 nM and 15.6 nM, respectively. The aptamer sensor chip is stable and reusable, and has potential for diluted human serum analysis. This assay presents strengths in simplicity, rapidity, low material consumption, real time analysis and ease of implementing high throughput and automatic detection. It is promising for application in clinical disease-related biomarkers analysis.