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Synthesis of Near-Infrared Emitting Gold Nanoclusters for Biological Applications
Published on: March 22, 2020
Brightly phosphorescent, environmentally responsive hydrogels containing a water-soluble three-coordinate gold(I)
Sreekar Marpu1, Zhibing Hu, Mohammad A Omary
1Department of Material Science and Engineering, University of North Texas, Denton, Texas 76203, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|September 15, 2010
Summary
New phosphorescent hydrogels using a gold complex show enhanced light emission, especially under physiological conditions, making them promising for bioimaging and drug delivery applications.
Area of Science:
- Materials Science
- Chemistry
- Biomedical Engineering
Background:
- Stimuli-responsive materials are crucial for advanced applications.
- Phosphorescent materials offer unique optical properties.
- Gold complexes are explored for luminescence due to their unique electronic structures.
Purpose of the Study:
- To synthesize stimuli-responsive phosphorescent hydrogel microspheres.
- To investigate the luminescence properties and sensitization of a gold(I) complex within a polymer network.
- To evaluate the potential of these hydrogels for biomedical applications like bioimaging and drug delivery.
Main Methods:
- Incorporation of a water-soluble phosphorescent gold(I) complex (Na(8)[Au(TPPTS)(3)]) into poly(N-isopropylacrylamide) (PNIPAM) polymer network.
- Synthesis of hydrogel microspheres and subsequent cross-linking into crystalline hydrogel networks.
- Characterization of luminescence properties through pH- and temperature-dependent titrations.
- Analysis of physical properties, including colloidal crystallinity and phase transition behavior.
Main Results:
- Significant sensitization (up to 2 orders of magnitude) of gold-centered emission within the phosphorescent hydrogels compared to the gold complex alone.
- Further enhancement of luminescence sensitization under physiological pH and temperature conditions.
- Preservation of PNIPAM microgel physical properties (crystallinity, phase transition) despite gold luminophore incorporation.
- Tunable emission from green (~525 nm) to turquoise (~490 nm) upon dehydration, linked to structural changes and a photoinduced Jahn-Teller distorted excited state model.
- Development of brightly phosphorescent, high-water-content crystalline hydrogel networks with enhanced stability.
Conclusions:
- The synthesized stimuli-responsive phosphorescent hydrogels exhibit remarkable luminescence sensitization and tunable emission properties.
- These gold-based phosphorescent hydrogels are highly sensitive to pH and temperature, showing great promise for bioimaging and drug delivery.
- The study presents a novel transition metal-based phosphorescent hydrogel system in an aqueous medium, distinct from traditional lanthanide-based phosphors.
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