Deacetylation-activated construction of single quantum dot-based nanosensor for sirtuin 1 assay

Why Is Longevity Still a Scientific Mystery? Sirtuins-Past, Present and Future

The sirtuin system consists of seven highly conserved regulatory enzymes responsible for metabolism, antioxidant protection, and cell cycle regulation. The great interest in sirtuins is associated with the potential impact on life extension. This article summarizes the latest research on the activity of sirtuins and their role in the aging process. The effects of compounds that modulate the activity of sirtuins were discussed, and in numerous studies, their effectiveness was demonstrated. Attention was paid to the role of a caloric restriction and the risks associated with the influence of careless sirtuin modulation on the organism. It has been shown that low modulators' bioavailability/retention time is a crucial problem for optimal regulation of the studied pathways. Therefore, a detailed understanding of the modulator structure and potential reactivity with sirtuins in silico studies should precede in vitro and in vivo experiments. The latest achievements in nanobiotechnology make it possible to create promising molecules, but many of them remain in the sphere of plans and concepts. It seems that solving the mystery of longevity will have to wait for new scientific discoveries.

Bsu polymerase-mediated fluorescence coding for rapid and sensitive detection of 8-oxo-7,8-dihydroguanine in telomeres of cancer cells

Guanine is the most susceptible to oxidation among all the DNA bases, and 8-oxo-7,8-dihydroguanine (OG) is one of main oxidation products that can occur in any part of chromosomal DNA. OG in the telomere sequence is associated with telomere shortening, cell aging, and dysfunction, and it may induce cancers. The accurate detection of OG in telomeres is important to early clinical diagnosis and molecular research. Herein, we develop a simple and rapid method to sensitively measure 8-oxo-7,8-dihydroguanine (OG) in telomeres of cancer cells by using Bsu polymerase-mediated fluorescence coding. This method is very simple without the requirement for any nucleic acid amplification or specific restriction enzyme recognition reaction, and Bsu polymerase can selectively incorporate Cy5-dATP into the opposite site of OG, endowing this method with good specificity. Moreover, the introduction of single-molecule detection significantly improves the sensitivity. This method can detect OG within 70 min with a limit of detection (LOD) of 2.45 × 10^-18 M, and it can detect OG in genomic DNA extracted from H₂O₂-treated HeLa cells with a LOD of 0.0094 ng, holding great potential in disease-specific gene damage research and early clinic diagnosis.

Development of a single quantum dot-mediated FRET biosensor for amplification-free detection of ten-eleven translocation 2

Ten-eleven translocation (TET) family proteins play key roles in multiple cellular processes by mediating the oxidation of 5-methylcytosine to directly participate in DNA demethylation, and often aberrantly expressed in various diseases. In this research, we develop a single-quantum-dot (QD)-mediated fluorescence resonance energy transfer (FRET) biosensor for amplification-free measurement of ten-eleven translocation 2 (TET2). When TET2 is present, it catalyzes the oxidation of 5-vinylcytosine in dsDNA to 5-formylmethylcytosine, and the subsequent labeling of dsDNA with Cy5 generates a biotinylated Cy5-dsDNA complex. Biotinylated Cy5-dsDNA complexes are conjugated to the streptavidin-coated 605QDs to obtain a Cy5-dsDNA-605QD nanostructures, inducing FRET from 605QD to Cy5. FRET signal can be simply measured by single-molecule counting. This biosensor enables homogeneous detection of TET2 with a limit of detection (LOD) of 0.042 ng/μL, and it can accurately measure cellular TET2 down to 1 cell. Moreover, this biosensor can be used to screen TET2 inhibitors, offering a new platform for TET2-related medical research and clinical diagnostics.