Influence of Nucleotide-biased Fluorescence Emissions of SYBR Green II on the Result Consistence of Rolling Circle Amplification

Electrophoretic characterization of LNP/AAV-encapsulated nucleic acids: Strengths and weaknesses

The use of nucleic acids (NAs) has revolutionized medical approaches and ushered in a new era of combating various diseases. Accordingly, there is an increasing demand for accurate identification, localization, quantification, and characterization of NAs encapsulated in nonviral or viral vectors. The vast spectrum of molecular dimensions and intra- and intermolecular interactions presents a formidable obstacle for NA analytical development. Typically, the comprehensive analysis of encapsulated NAs, free NAs, and their spatial distribution poses a challenge that is seldom tackled in its complete complexity. The identification of appropriate physicochemical methodologies for large nonencapsulated or encapsulated NAs is particularly intricate and necessitates an evaluation of the analytical outcomes and their appropriateness in addressing critical quality attributes. In this work, we examine the analytics of non-encapsulated or encapsulated large NAs (>500 nucleotides) utilizing capillary electrophoresis (CE) and liquid chromatography (LC) methodologies such as free zone CE, gel CE, affinity CE, and ion pair high-performance liquid chromatography (HPLC). These methodologies create a complete picture of the NA's critical quality attributes, including quantity, identity, purity, and content ratio.

Using Peptide Nucleic Acid Hybridization Probes for Qualitative and Quantitative Analysis of Nucleic Acid Therapeutics by Capillary Electrophoresis

The space of advanced therapeutic modalities is currently evolving in rapid pace necessitating continuous improvement of analytical quality control methods. In order to evaluate the identity of nucleic acid species in gene therapy products, we propose a capillary electrophoresis-based gel free hybridization assay in which fluorescently labeled peptide nucleic acids (PNAs) are applied as affinity probes. PNAs are engineered organic polymers that share the base pairing properties with DNA and RNA but have an uncharged peptide backbone. In the present study, we conduct various proof-of-concept studies to identify the potential of PNA probes for advanced analytical characterization of novel therapeutic modalities like oligonucleotides, plasmids, mRNA, and DNA released by recombinant adeno-associated virus. For single-stranded nucleic acids up to 1000 nucleotides, the method is an excellent choice that proved to be highly specific by detecting DNA traces in complex samples, while having a limit of quantification in the picomolar range when multiple probes are used. For double-stranded samples, only fragments that are similar in size to the probe could be quantified. This limitation can be circumvented when target DNA is digested and multiple probes are used opening an alternative to quantitative PCR.

Signal-on electrochemical DNA (E-DNA) sensor for accurate quantification of nicking-assisted rolling circle amplification (N-RCA) products with attomolar sensitivity

Rolling circle amplification (RCA) has become an increasingly important amplification technique in nucleic acid analysis, immunoassay, and molecular diagnosis due to its high specificity and sensitivity. However, the accurate quantification of RCA products via the extensively used fluorescent signaling method has been challenged primarily by the non-specific and sequence-independent binding of the fluorescent dyes to DNA. Here, we have developed a signal-on E-DNA sensor for accurate quantification of the RCA products with high specificity and sensitivity. A restriction enzyme was introduced to cleave the long tandem repeat sequences generated in the RCA reaction into many short monomers. The short monomers were then used as secondary targets to trigger the E-DNA sensor to produce an amplified redox current and thus the resulting RCA products were detected. The method was successfully applied to the detection of miR-7a with high specificity and the detection limit was as low as 0.59 fM.