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Abstract: DNAzyme and aptamer conjugations have already been used for sensitive and accurate detection of several molecules. In this study, we tested the relationship between conjugation orientation of DNAzyme and aflatoxin B1 aptamer and their subsequent peroxidase activity. Circular dichroism (CD) spectroscopy and biochemical analysis were used here to differentiate between these two conjugation patterns. Results showed that DNAzyme–aptamer has more catalytic activity and efficiency than aptamer–DNAzyme. Thereby, DNAzyme–aptamer with its superior efficiency can be used for design and development of more sensitive aflatoxin B1 DNA based biosensors. [ABSTRACT FROM AUTHOR]

Protein specific aptamers are highly applicable affinity ligands in different fields of research and clinical applications. They have been developed against various targets, in particular, biomacromolecules such as proteins. Among human proteins, the coagulation factors are the most attractive targets for aptamer selection and their specific aptamers have valuable characteristics in therapeutic and analytical applications. In this study, a plasma derived coagulation factor VIII was considered as the protein target for DNA aptamer selection using size exclusion chromatography-SELEX. Potential aptameric oligonucleotides with high affinity and specificity were achieved during eight rounds of selection. Binding affinity constant of selected aptamer and aptameric enriched pool were in nanomolar range that was comparable to monoclonal antibodies. Further improvement studies can result in aptamers that are more promising as an industrial affinity ligand for the purification of anti-hemophilia factor from plasma source. [ABSTRACT FROM AUTHOR]

The development of enhanced drug delivery systems is one of the most attractive fields of pharmaceutical sciences, as some of the highly effective chemo/biotherapeutics for cancer treatment can not be administrated due to their high toxicities for normal cells or low stability in physiological media. However, drugs that are currently not administrable will become valuable if specific cell-targeted drug carriers can protect the normal cells from adverse effects and also improve drug pharmacokinetics. Aptamers are attractive and promising biomaterials developed with high affinity and specificity against numerous valuable targets. They could act similar to monoclonal antibodies (mAbs), and offer significant advantages. Combined with aptamers, nanostructures are smart veicles with remarkable properties for drug delivery. Combination of aptamer and nanotechnology has resulted in the production of various targeted drug delivery systems which are highly efficient in therapeutic and diagnostic applications. In this review, some of the efforts related to design and development of aptamer-targeted nanocarriers have been summarized considering: i) Aptamer importance as smart ligands and the aptamer development methods ii) Types of nanostructures combined with aptamers as targeting agent proposed in the literature iii) Cancer specific aptamers evaluated in combination with nanocarriers for diagnostic and therapeutic applications and iv) Discussion of aptamer-based smart nanocarriers according to the trend of related research works. [ABSTRACT FROM AUTHOR]

Aptamers, or single stranded oligonucleotides, are produced by systematic evolution of ligands by exponential enrichment, abbreviated as SELEX. In the amplification and regeneration step of SELEX technique, dsDNA is conversed to ssDNA. Asymmetric PCR is one of the methods used for the generation of ssDNA. The purpose of this study was to design a random DNA library for selection of aptamers with high affinity for protein targets and develop an efficient asymmetric PCR amplification. Thus, the influence of factors including annealing temperature, number of amplification cycles, primer ratio, Mg2+ concentration and the presence of a PCR enhancer on the amplification of the desired product were evaluated. Results obtained by agarose gel electrophoresis showed that the annealing temperature of 64 °C, Mg2+ concentration of 0.25 mM, reverse to forward primer ratio of 15:1, amplification cycle of 25 and the presence L-ectoin as a PCR enhancer with the concentration of 0.4 M were the optimal conditions. Our results supported that the yield of this type of ssDNA production is sufficient for combinatorial screening of aptamers. [ABSTRACT FROM AUTHOR]