Formation of Visible Aggregates between Rolling Circle Amplification Products and Magnetic Nanoparticles as a Strategy for Point-of-Care Diagnostics

Visual detection of rolling circle amplification products (RCPs) has been achieved by specific aggregation with magnetic nanoparticles. The method presented here reliably generates aggregates in 1.5 h; these are visible to the naked eye in samples containing at least 0.4 fmol of RCPs. In addition, alternate current susceptometry and absorbance spectroscopy have also been used to quantify the amplified products. The specificity of the detection method was tested, and no non-specific aggregation was detected in samples containing up to 20 fmol of non-complementary amplified DNA. This method is a versatile tool for detecting pathogenic DNA in point-of-care diagnostics, with no readout equipment required. However, chips and automated assays can be used in conjugation with the developed method since detection and quantification can be achieved by commercially available readout instruments.

Automated summary

Visual detection of rolling circle amplification products (RCPs) has been successfully achieved using specific aggregation with magnetic nanoparticles. This versatile method can reliably generate aggregates visible to the naked eye in a short time without requiring any readout equipment, making it highly specific for pathogenic DNA detection in point-of-care diagnostics. The method has been tested for specificity and demonstrated no non-specific aggregation even in samples containing high levels of non-complementary amplified DNA.