Biology subjects

Ijäs, H.

Publications and source records attributed to Ijäs, H..

3 recordsLinked to original sources

bioRxiv2024

DNA Origami Signal Amplification in LateralFlow Immunoassays

Lateral flow immunoassays (LFIAs) enable a rapid detection of analytes in a simple, paper-based test format. Despite their multiple advantages, such as low cost and ease of use, their low sensitivity compared to laboratory-based testing limits their use in e.g. many critical point-of-care applications. Here, we present a DNA origami-based signal amplification technology for LFIAs. DNA origami is used as a structurally precise adapter to connect detection antibodies to tailored numbers of signal-generating labels. As a proof of concept, we apply the DNA origami signal amplification in a sandwich-based LFIA for the detection of cardiac troponin I (cTnI) in human serum. We show a 55-fold improvement of the assay sensitivity with 40 nm gold nanoparticle labels and an adjustable signal amplification of up to 125-fold with fluorescent dyes. The technology is compatible with a wide range of existing analytes, labels, and sample matrices, and presents a modular approach for improving the sensitivity and reliability of lateral flow testing.

biophysics↗

bioRxiv2024

Fluorescence Anisotropy Analysis of the Interaction between Doxorubicin and DNA Origami Nanostructures

Owing to doxorubicins high DNA binding affinity, doxorubicin-loaded DNA origami nanostructures (DOX-DONs) are promising nanocarriers against cancer. However, understanding the interactions between doxorubicin (DOX) and DNA origami nanostructures (DONs) is important to ensure the quality of DOX-DONs. This interaction is often taken for granted and the influence of DOX loading conditions is poorly characterized. Exploiting the inherent fluorescence of DOX, steady-state and time-resolved fluorescence anisotropy spectroscopy techniques are used for characterizing non-destructively the binding between DOX and DONs, and the purity of formed complexes. The difference in fluorescence anisotropy between free DOX and DOX-DONs confirms the DOX-DON complex formation. Further, at loading ratios of DOX to DNA base pairs > 0.5, homo-Forster resonance energy transfer (homo-FRET) between closely packed DOX molecules is observed. Moreover, time-resolved anisotropy reveals DOX aggregation on DONs at high loading ratios > 1. For loading ratios > 0.1, spin-filtration to remove excess free DOX is efficient and necessary, though at loading ratios > 1 some DOX aggregates remain attached to the DONs. In summary, fluorescence anisotropy analysis provides more detailed information and insight into DOX-DONs compared to regularly used fluorescence intensity-based characterization methods, and these results can help designing more efficient and safer DNA intercalator-based nanocarriers.

biochemistry↗

bioRxiv2020

Unraveling the interaction between doxorubicin and DNA origami nanostructures for customizable chemotherapeutic drug release

Doxorubicin (DOX) is a common drug in cancer chemotherapy, and its high DNA-binding affinity can be harnessed in preparing DOX-loaded DNA nanostructures for targeted delivery and therapeutics. Although DOX has been widely studied, the existing literature of DOX-loaded DNA-carriers remains limited and incoherent. Here, based on an in-depth spectroscopic analysis, we characterize and optimize the DOX loading into different 2D and 3D scaffolded DNA origami nanostructures (DONs). In our experimental conditions, all DONs show similar DOX binding capacities (one DOX molecule per two to three base pairs), and the binding equilibrium is reached within seconds, remarkably faster than previously acknowledged. To characterize drug release profiles, DON degradation and DOX release from the complexes upon DNase I digestion was studied. For the employed DONs, the relative doses (DOX molecules released per unit time) may vary by two orders of magnitude depending on the DON superstructure. In addition, we identify DOX aggregation mechanisms and spectral changes linked to pH, magnesium, and DOX concentration. These features have been largely ignored in experimenting with DNA nanostructures, but are probably the major sources of the incoherence of the experimental results so far. Therefore, we believe this work can act as a guide to tailoring the release profiles and developing better drug delivery systems based on DNA-carriers.

biochemistry↗