Related Experiment Video
Updated: May 15, 2026
16:19
Synthesis, Cellular Delivery and In vivo Application of Dendrimer-based pH Sensors
Published on: September 10, 2013
Highly sensitive fluorescent and colorimetric pH sensor based on polyethylenimine-capped silver nanoclusters.
Fei Qu1, Nian Bing Li, Hong Qun Luo
1Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
Langmuir : the ACS Journal of Surfaces and Colloids
|January 4, 2013
Summary
New silver nanoclusters coated with polyethylenimine (PEI) function as sensitive fluorescent and colorimetric pH sensors. These nanoclusters offer rapid pH detection with visible color changes and fluorescence shifts, proving valuable for biological and medical applications.
Area of Science:
- Nanotechnology
- Materials Science
- Analytical Chemistry
Background:
- Developing sensitive and rapid pH sensors is crucial for various scientific fields.
- Existing pH sensors may have limitations in sensitivity, response time, or applicability in specific environments.
- Silver nanoclusters offer unique optical properties suitable for sensing applications.
Purpose of the Study:
- To develop a novel, highly sensitive fluorescent and colorimetric pH sensor using silver nanoclusters capped with hyperbranched polyethylenimine (PEI).
- To investigate the pH-responsive behavior, including colorimetric and fluorescent changes, of the PEI-capped silver nanoclusters.
- To evaluate the potential applications of this sensor in biological, medical, and pharmaceutical fields.
Main Methods:
- Synthesis of silver nanoclusters capped with hyperbranched polyethylenimine (PEI).
- Characterization of the optical properties (absorption and fluorescence) of the PEI-capped Ag nanoclusters.
- Testing the sensor's response to varying pH levels and buffer solutions.
- Evaluating the influence of ionic strength on the sensor's performance.
Main Results:
- The PEI-capped Ag nanoclusters exhibited a rapid response to pH fluctuations, changing color from colorless to colored with increasing acidity.
- Fluorescence intensity showed a linear response in the pH range of 5.02-7.96, with a 10-fold increase at higher pH.
- Decreasing pH induced aggregation of nanoclusters, causing color change and fluorescence quenching.
- The sensor demonstrated sensitivity to different buffer solutions, with minimal influence from ionic strength.
Conclusions:
- PEI-capped Ag nanoclusters serve as effective colorimetric and fluorescent pH indicators.
- The sensor exhibits high sensitivity, rapid response, and a broad linear detection range.
- Its nanoscaled dimensions and properties make it a promising candidate for applications in biological, medical, and pharmaceutical settings.
