DNAzyme sensor for selective manganese ion detection in biological systems

A selective DNAzyme-based fluorescent sensor detects manganese ions in cells by lighting up when Mn²⁺ binds, allowing precise monitoring of manganese levels for biological research and potential therapies.

Background

Manganese (Mn²⁺) is an essential trace element integral to numerous biological processes, acting as a vital cofactor for enzymes involved in metabolic pathways, antioxidant defenses, and immune responses. Its role extends to advanced therapeutic applications, including the development of manganese-based nanomaterials for antitumor therapies. Accurate detection and monitoring of Mn²⁺ levels within biological systems are crucial for understanding its physiological functions, maintaining cellular homeostasis, and optimizing medical treatments that harness its biochemical properties.

Despite its importance, existing methods for Mn²⁺ detection present significant limitations that impede their effectiveness in biological contexts. Traditional techniques, such as atomic absorption spectroscopy and inductively coupled plasma mass spectrometry, while highly sensitive, require extensive sample preparation and are unsuitable for real-time or in vivo analyses. Additionally, these methods lack the spatial resolution necessary for intracellular studies. Fluorescent probes and molecular sensors currently available often suffer from poor selectivity, leading to interference from other biologically abundant ions like calcium, magnesium, and zinc, which complicates accurate Mn²⁺ quantification. Furthermore, many existing sensors have limited sensitivity and dynamic range, restricting their ability to detect subtle fluctuations in Mn²⁺ concentrations essential for detailed biological and clinical investigations.

Technology description

A DNAzyme-based fluorescent sensor has been developed for the highly selective detection of Mn²⁺ ions in biological systems. Utilizing the 11-5 DNAzyme identified through an in vitro selection process, the sensor is configured in a trans-cleaving format with separate enzyme and substrate strands. It features a Cy5 fluorophore and two BHQ2 quenchers, enabling a “turn-on” fluorescence response when Mn²⁺ induces cleavage.

The sensor exhibits a dissociation constant of 420 μM, operates effectively within a linear range below 100 μM Mn²⁺, and demonstrates impressive selectivity ratios of 480-fold over Ca²⁺, 174-fold over Mg²⁺, and 320-fold over Zn²⁺. Additionally, it shows minimal interference from other physiological ions and efficiently localizes within the endoplasmic reticulum and mitochondria of various cell types. Stability during transfection ensures reliable intracellular Mn²⁺ monitoring, making it suitable for applications such as image-guided antitumor therapy and tracking MnOx nanoparticle degradation in cancer cells.

This technology stands out due to its exceptional selectivity for Mn²⁺, achieved through a rigorous in vitro selection process that included counter-selection against competing metal ions. The identification and utilization of the 11-5 DNAzyme enable a robust fluorescent detection mechanism with high selectivity ratios, surpassing existing manganese detection methods. Its design minimizes interference from other ions, ensuring accurate Mn²⁺ measurements in complex biological environments. Furthermore, the sensor’s ability to efficiently distribute within cells and maintain stability during transfection enhances its practical applicability for real-time monitoring of intracellular manganese levels. These unique attributes make it a valuable tool for both research and potential clinical applications, particularly in studying manganese-related biological processes and optimizing manganese-based therapeutic strategies.

Benefits

Highly selective Mn²⁺ detection with minimal interference from other metal ions
“Turn-on” fluorescence mechanism for enhanced signal clarity
Efficient cytosolic distribution and localization in endoplasmic reticulum and mitochondria
Stable during transfection, ensuring reliable intracellular Mn²⁺ monitoring
Versatile applications in immune cell activation monitoring and nanoparticle degradation tracking
Potential for use in image-guided antitumor therapy