Functional single-chain polymer nanoparticles for biomedical photoacoustic tomography

• Applicants: Professor Dr. Wolfgang Binder; Professor Jan Laufer, Ph.D.
• Subject Area: Medical Physics, Biomedical Technology ; Preparatory and Physical Chemistry of Polymers
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542011057

Molecular photoacoustic (PA) tomography is a hybrid imaging technique that combines strong absorption-based contrast and spectral specificity of purely optical imaging modalities with high spatial resolution of ultrasound. Since the scattering of acoustic waves in tissue is orders of magnitude lower compared to that of light, PA imaging offers high resolution images at depths beyond those offered by purely optical methods. To visualize tissues that are transparent to visible and nearinfrared excitation wavelengths, contrast agents are typically required. The challenge of detection lies in their low abundance, and hence weak contrast, against the overwhelming background of hemoglobin. To enable sensitive detection, new contrast agents are required that possess unique photophysical properties. In addition, novel experimental methods are needed that exploit these properties for detection, thus overcoming the limitations of conventional unmixing approaches. The contrast agents should also offer added functionality, such as the possibility to sense and measure local biophysical and biochemical parameters. In this project, single-chain polymer nanoparticles (SCNP) loaded with dye molecules will be developed for PA and optical imaging. They offer strong absorption, small size, suitable surface properties for targeting, and biocompatibility. Their unique photophysical properties, such as a strong nonlinear PA response, pave the way for the development of highly sensitive and unambiguous detection methods that are based on simple experimental approaches, such as pump-probe excitation. SCNP will also offer a versatile platform for the development of novel contrast agents that act as biosensors of specific chemical species, such as ions or enzymes, or biophysical parameters, such as pH.

• DFG Programme: Research Grants