An “off-on” fluorescent switch assay for microRNA using nonenzymatic ligation-rolling circle amplification

Enzyme-free synthesis of cyclic single-stranded DNA constructs containing a single triazole, amide or phosphoramidate backbone linkage and their use as templates for rolling circle amplification and nanoflower formation

“…The second study used a triazole-containing DNA template in an RCA-based fluorogenic assay for microRNA, but the authors did not compare the efficiency of the RCA reaction with that of an unmodified template. 46 In this work we also investigate amide and phosphoramidate chemical linkages ( Fig. 1(ii)B and C ), both of which can be formed by di-imide coupling chemistry.…”

“…This is a salient observation given that a recent publication uses a triazole-containing cyclic template with φ-29 in an RCA-based fluorescent switch-based diagnostic assay for microRNA detection. 46 It is also interesting that during RCA of the amide- and triazole-modified templates 1 _Am, 1 _Tz and 2 _Am the proportion of double-stranded side-products appears to increase with extended amplification time. In contrast the relative proportions of the bands assigned to single- and double-stranded products respectively appear to stay approximately constant throughout the course of the RCA reactions for all of the unmodified and phosphoramidate-modified templates (Fig.…”

A highly sensitive miR-195 nanobiosensor for early detection of Parkinson’s disease

“…These miRNA electrochemical nanobiosensors can be implied for the quantification of different miRNAs for detection of different diseases, such as lung cancer [31], breast cancer [24], gastric cancer [32], glioma [33], Alzheimer [34], etc. But, beside the electrochemical methods, there are other types of high-performance nanobiosensors such as fluorescent methods which can be applied for miRNA quantification and responded very well [35][36][37][38].…”

Polycytosine DNA Electric-Current-Generated Immunosensor for Electrochemical Detection of Human Epidermal Growth Factor Receptor 2 (HER2)

“…It can utilize the Ab to capture analytes from large volumes of sample by using magnets to separate the captured analytes and detecting the captured analytes in the sandwich assay described in stages II and III. Another possible configuration integrates detection with PCR DNA amplification, , rolling circle amplification (RCA), − or hybridization chain reaction (HCR), − thereby enabling an increase in DNA phosphate concentration and resulting in increased electrical signal when reacting with Na 2 MoO 4. Therefore our approach can be used in a wide array of applications for different bioassays to meet varying clinical and analytical needs.…”

“…Successful design of a sensitive and precise immunosensor for detection of protein biomarkers requires careful selection of both binding ligands and signal amplification strategies. − While immunoassays are widely used for detection, sensitivity is limited for many analytes because assay signal generating modes (e.g., enzymatic assays, colorimetric detection, chemiluminescence, and fluorescence) are often difficult to amplify. Recently, DNA strand ligands such as aptamers were developed as alternatives to traditional antibodies for different analyte targets. − While aptamers have the advantages of low cost, easy synthesis, and potential for signal amplification, antibodies remain the most common ligands for biodetection applications , even though DNA-based signal strategies are versatile and easy to amplify. , Immunoassays can be made orders of magnitude more sensitive by replacing the conventionally used enzyme probes with amplifiable DNA probes utilizing polymerase chain reaction (PCR), , rolling circle amplification (RCA), − or hybridization chain reaction (HCR). − Previous efforts have combined the specificity of an immunoassay with DNA-based signal amplification strategies such as immunoassays with PCR (immuno-PCR) and immunoassays with RCA (immuno-RCA). − Although these methods are highly sensitive, they are not widely used because of their complexity. For example, for immuno-PCR, antibodies must be conjugated to the DNA strand, and very precise cycling temperatures are required along with special equipment to detect the amplicon.…”