Amplified Split Aptamer Sensor Delivered Using Block Copolymer Nanoparticles for Small Molecule Imaging in Living...

Area of Science:

• Biomedical Engineering
• Molecular Biology
• Nanotechnology

Background:

• Developing sensitive and specific biosensors for small molecules in living cells remains a challenge.
• Existing methods often struggle with low signal-to-background ratios, limiting imaging contrast.
• Efficient and trackable delivery of DNA probes into cells is crucial for intracellular sensing.

Purpose of the Study:

• To develop a novel amplified split aptamer sensor for highly sensitive detection and imaging of small molecules in living cells.
• To utilize cationic block copolymer nanoparticles (BCNs) as fluorescent nanocarriers for efficient DNA probe delivery and self-tracking.
• To enhance signal-to-background ratio for high-contrast imaging of weakly interacting small molecules.

Main Methods:

• A split aptamer system was designed to initiate a hybridization chain reaction (HCR) for signal amplification.
• Fluorescent cationic block copolymer nanoparticles (BCNs) were synthesized to encapsulate and deliver DNA probes.
• The BCNs' fluorescence enabled real-time tracking of probe delivery within living cells.
• In vitro and live-cell experiments were conducted to evaluate sensor sensitivity, selectivity, and imaging capabilities for adenosine triphosphate (ATP).

Main Results:

• BCNs demonstrated high fluorescence brightness, allowing for direct tracking of their intracellular delivery.
• The amplified split aptamer sensor achieved a low detection limit of 30 nM for adenosine triphosphate (ATP) in vitro.
• Live cell studies confirmed a "signal on" approach for specific and high-contrast imaging of intracellular ATP.
• The sensor exhibited high sensitivity and selectivity for target small molecules.

Conclusions:

• The developed amplified split aptamer sensor offers a highly sensitive and specific platform for detecting and imaging small molecules in living cells.
• Fluorescent BCNs provide an efficient and self-tracking delivery system for DNA probes, overcoming transfection challenges.
• This HCR-based DNA sensor system presents a broadly applicable platform for the detection and imaging of low-abundance biomarkers in biological systems.