Label-Free Detection of DNA Polymerase Activity Using Hairpin DNA-Templated Silver Nanoclusters.

Based on the characteristic properties like strong fluorescence and high photostability, DNA-templated silver nanoclusters (DNA-AgNCs) were utilized to detect Klenow fragment exo- (KF-) activity and to monitor its inhibition by daidzein. In this study, fluorescence intensity is linearly correlated for KF- concentration ranging from 0 to 2.0 U/mL, with a minimum detectable concentration of 0.05 U/mL. In addition, KF- inhibition was monitored by changes in fluorescence intensity with increasing daidzein concentration gradually.

The detection of a mismatched DNA by using hairpin DNA-templated silver nanoclusters.

Fluorescence assays have been developed to detect biomolecules using DNA-templated silver nanoclusters (DNA-AgNCs) utilizing their unique physical and optical properties. This study was designed to detect single-mismatched DNA by the hybridization of target DNA to template DNA either before or after DNA-AgNCs synthesis. The results showed that the detection specificity of a single-mismatched DNA was clearly enhanced when the target DNA (cDNA) was hybridized to template DNA prior to DNA-AgNCs synthesis compared with cDNA hybridization subsequent to DNA-AgNCs synthesis.

A Label-Free Detection of NdeI Endonuclease Activity by Using DNA-Templated Silver Nanoclusters.

Restriction endonucleases play an important role in genetic recombination, molecular cloning, clinical diagnosis, and pharmacological application in drug studies. In the present study, DNA-templated Ag+ nanoclusters (DNA-AgNCs) were used to detect NdeI endonuclease activity due to their facile synthesis, outstanding optical properties, and good biocompatibility. This study monitored fluorescence intensity of DNA-AgNCs to detect NdeI endonuclease activity and its inhibition in the presence of 5-fluorouracil under optimal conditions.

Effect of pH and Salt on Adsorption of Double-Stranded DNA on Graphene Oxide.

Graphene oxide (GO) has a large surface-to-volume ratio and hydrophobic hexagonal rings that can interact with biomolecules. Single-stranded DNA adsorbs strongly to the surface of GO via hydrophobic interactions. GO has been used in optical biosensors and biomedical platforms for the detection of DNA, proteins, and small molecules. This study was designed to measure the adsorption of double-stranded DNA (dsDNA) onto GO according to DNA length, salt concentration, and pH of the reaction. Results showed that dsDNA molecules were adsorbed progressively as the pH changed from 6.0 to 4.0. At high pH, dsDNA adsorption was enhanced by the presence of MgCl2 rather than NaCl. Desorption of DNA from GO, with triton X-100 led to the rapid release of DNA from GO in the presence of MgCl2.

Characterizing Fluorescence Emissions of Hairpin DNA-Templated Silver Nanoclusters by cDNA Hybridization.

Stem-loop hairpin DNA probes have high hybridization specificity and unique selectivity to target molecules such as DNA and small molecules. DNA-templated silver nanoclusters (DNA-AgNCs) has been widely used to detect biomolecules of interest due to the photostable, bright, and efficient methods. In this study, we measured fluorescence emission of hairpin DNA upon hybridization with cDNA and mutant cDNA (cDNA-1) or mutant cDNA containing mismatched bases in the stem region (cDNA-2). Fluorescence intensity of hairpin DNA-AgNCs in the presence of cDNA was 1.80 times higher than that of hairpin DNA-AgNCs alone, but decreased to 66% in the presence of cDNA-1 containing mismatched base corresponding to the hairpin stem region. This study demonstrated that fluorescence intensities of hairpin DNA-AgNCs were dependent on hybridization with either wild-type and mutant cDNAs.

Label-free rapid and simple detection of exonuclease III Activity with DNA Templated Copper Nanoclusters.

In this study, DNA-templated copper nanoclusters (DNA-CuNCs) were used to detect exonuclease III (Exo III) activity, which is important for the diagnosis and therapy of several diseases. The results of this study showed that Exo III was affected by the concentrations of magnesium ions and sodium ions, and its optimal conditions for cleavage were 5 mM Mg2+ and less than 25 mM Na+. With a blunt-end DNA, more than 98% of DNA was digested by Exo III. As expected, with two or four cytosines in the terminal position of a 4-base overhanging DNA such as 5'-GGCC-3' and 5'-CCCC-3', there was little cleavage by Exo III compared to with a blunt-end DNA.

Photoprotective effects of apple peel nanoparticles.

Plants contain enriched bioactive molecules that can protect against skin diseases. Bioactive molecules become unstable and ineffective due to unfavorable conditions. In the present study, to improve the therapeutic efficacy of phytodrugs and enhance photoprotective capability, we used poly(D,L-lactide-co-glycolide) as a carrier of apple peel ethanolic extract (APETE) on permeation-enhanced nanoparticles (nano-APETE). The in vitro toxicity of nano-APETE-treated dermal fibroblast cells were studied in a bioimpedance system, and the results coincided with the viability assay. In addition, the continuous real-time evaluations of photodamage and photoprotective effect of nano-APETE on cells were studied. Among three different preparations of nano-APETE, the lowest concentration provided small, spherical, monodispersed, uniform particles which show high encapsulation, enhanced uptake, effective scavenging, and sustained intracellular delivery. Also, the nano-APETE is more flexible, allowing it to permeate through skin lipid membrane and release the drug in a sustained manner, thus confirming its ability as a sustained transdermal delivery. In summary, 50 µM nano-APETE shows strong synergistic photoprotective effects, thus demonstrating its higher activity on target sites for the treatment of skin damage, and would be of broad interest in the field of skin therapeutics.

Measurement of DNA helical change for the binding of cyclic AMP receptor protein to lac DNA.

Cyclic AMP receptor protein (CRP) binds to DNA and induces DNA bending. DNA bending plays an important role in transcription activation of many genes in Escherichia coli. To know DNA helical change by CRP, we used molar cyclization factor (j(M)), which is sensitive to helical twist or torsional alignment. Six consecutive DNA fragments were constructed that contained phasing sequence at left arm and CRP binding site in center. j(M) values measured in this study were approximately 10 times increased by CRP relative to that measured for DNA only. The analysis of set of j(M) values indicated that CRP induced DNA bending without the helical change like helical twisting or torsional alignment change.