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Detecting Anastasis In Vivo by CaspaseTracker Biosensor
Published on: February 1, 2018
Highly sensitive and selective SERS detection of caspase-3 during cell apoptosis based on the target-induced hotspot
Yueyuan Zhuang1, Han Dong1, Tianqing Liu2
1School of Pharmacy, Nantong University, Nantong, Jiangsu, 226001, China. dsun1203@ntu.edu.cn.
Abstract:
Caspase-3 is an important biomarker for the process of apoptosis, which is a key target for cancer treatment. Due to its low concentration in single cells and the structural similarity of caspase family proteins, it is exceedingly challenging to accurately determine the intracellular caspase-3 during apoptosis in situ. Herein, a biosensing strategy based on the target-induced SERS "hot spot" formation has been developed for the simultaneous highly sensitive and selective detection of intracellular caspase-3 level. The nanosensor is composed of gold nanoparticles modified with the probe molecule 4-mercaptophenylboronic acid (4-MPBA) and a peptide chain. The well-designed peptide chain contains two distinct functional domains, one with a sulfhydryl group for bonding to the gold nanoparticles and the other a fragment specifically recognized by caspase-3. When caspase-3 is present, the negatively charged segment (NH2-Asp-Asp-Asp-Glu-Val-Asp-OH) of the peptide chain is specifically hydrolyzed, leaving a positively charged fragment coated on the surface of the gold nanoparticles. At this time, the golden nanoparticles undergo significant coupling aggregation due to the electrostatic interaction, resulting in a large number of SERS "hot spot" formation. The SERS signal of the 4-MPBA located at the nano-gap is significantly boosted because of the local plasma enhancement effect. The highly sensitive determination of caspase-3 can be achieved according to the altered SERS signal intensity of 4-MPBA. The turn-on of the SERS signal-induced target contributes to the excellent selectivity and the formation of the SERS "hot spot" effect that further improves the sensitivity of caspase-3 detection. The advantages of this biosensing technique allow for the precise in situ monitoring of the dynamic changes in caspase-3 levels during apoptosis. In addition, the differences in caspase-3 levels during the apoptosis of various cell types were compared. Monitoring the caspase-3 levels can be used to track the cellular apoptosis process, evaluate the effect of drugs on cancer cells in real time, and provide guidance for the selection of the appropriate drug dosage.
Insights
A novel biosensor detects intracellular caspase-3 (a cancer treatment target) using SERS hot spot formation. This method enables sensitive and selective *in situ* monitoring of apoptosis, aiding cancer drug development.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Nanotechnology
Background:
- Caspase-3 is a crucial biomarker for apoptosis and a target in cancer therapy.
- Intracellular detection of caspase-3 is challenging due to low concentrations and protein similarity.
- Accurate *in situ* monitoring is vital for understanding apoptosis and evaluating cancer treatments.
Purpose of the Study:
- To develop a highly sensitive and selective biosensing strategy for intracellular caspase-3 detection.
- To utilize Surface-Enhanced Raman Spectroscopy (SERS) and "hot spot" formation for enhanced detection.
- To enable precise *in situ* monitoring of caspase-3 dynamics during apoptosis.
Main Methods:
- A nanosensor was designed using gold nanoparticles functionalized with 4-mercaptophenylboronic acid (4-MPBA) and a specific peptide chain.
- Caspase-3 activity triggers peptide hydrolysis, leading to gold nanoparticle aggregation and SERS "hot spot" formation.
- Changes in SERS signal intensity of 4-MPBA correlate with intracellular caspase-3 levels.
Main Results:
- The biosensor demonstrated high sensitivity and selectivity for intracellular caspase-3 detection.
- The SERS signal significantly amplified due to "hot spot" formation and local plasma enhancement.
- The study successfully monitored caspase-3 levels *in situ* and compared differences across cell types.
Conclusions:
- The developed SERS-based biosensor provides a precise tool for real-time monitoring of cellular apoptosis.
- This technique can effectively evaluate drug efficacy on cancer cells and guide dosage selection.
- The biosensing strategy offers a promising approach for advancing cancer diagnostics and therapeutics.
