Microplate chemiluminescent assay for HBV DNA detection using 3-(10'-phenothiazinyl)propionic acid/N-morpholinopyridine pair as enhancer of HRP-catalyzed chemiluminescence

A sensitive sandwich assay for hepatitis B virus (HBV) DNA detection based on use of commercial CL-ELISA microplates was developed. To reveal the target the covalent conjugate of reporter oligonucleotide and horseradish peroxidase (HRP) was synthesized. An employment of enhanced chemiluminescence reaction, where 3-(10'-phenothiazinyl)propionic acid/N-morpholinopyridine pair was used as enhancer of HRP-catalyzed chemiluminescence, permitted to measure the enzyme activity of the conjugate with high sensitivity. Under the favorable conditions the limit of detection and a linear range of the assay were 3 pM and 0.07-2.0 nM, respectively. The coefficient of variation (CV) for determination of HBV DNA concentrations within the working range was lower than 4%. The obtained results demonstrated that the developed assay had high sensitivity and precision.

An enzyme-free and resettable platform for the construction of advanced molecular logic devices based on magnetic beads and DNA

A series of multiple logic circuits based on magnetic beads and DNA are constructed to perform resettable nonarithmetic functions, including a digital comparator, 4-to-2 encoder and 2-to-3 decoder, 2-to-1 encoder and 1-to-2 decoder. The signal reporter is composed of a G-quadruplex/NMM complex and a AuNP-surface immobilized molecular beacon. It is the first time that the designed DNA-based nonarithmetic nanodevices can share the same DNA platform with a reset function, which has great potential application in information processing at the molecular level. Another novel feature of the designed system is that the developed nanodevices are operated on a simple DNA/magnetic bead platform and share a constant threshold setpoint without the assistance of any negative logic conversion. The reset function is realized by heating the output system and the magnetic separation of the computing modules. Due to the biocompatibility and design flexibility of DNA, these investigations may provide a new route towards the development of resettable advanced logic circuits in biological and biomedical fields.

Reconfigurable and resettable arithmetic logic units based on magnetic beads and DNA

Based on the characteristics of magnetic beads and DNA, a simple and universal platform was developed for the integration of multiple logic gates to achieve resettable half adder and half subtractor functions. The signal reporter was composed of a split G-quadruplex DNAzyme and AuNP-surface immobilized molecular beacon molecule. The novel feature of the designed system is that the inputs (split G-quadruplexes) can interact with hairpin-modified Au NPs linked to magnetic particles. Another novel feature is that the logic operations can be reset by heating the output system and by using the magnetic separation of the computing modules. Moreover, the developed half adder and half subtractor are realized on a simple DNA/magnetic bead platform in an enzyme-free system and share a constant threshold setpoint. Due to the diversity and design flexibility of DNA, these investigations may provide a new method for the development of resettable DNA-based arithmetic operations.

Highly efficient colorimetric detection of ATP utilizing a split aptamer target binding strategy and superior catalytic activity of graphene oxide–platinum/gold nanoparticles

The specific binding of ATP and its aptamer linked the split aptamer-modified GO/PDDA/PtAuNPs and magnetic beads together. Using magnetic separation, TMB was catalyzed into a colored product by nanocomposites, which enabled rapid detection of ATP.