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Poly[N-(2-hydroxypropyl)methacrylamide] polymers diffuse in brain extracellular space with same tortuosity as small
S Prokopová-Kubinová1, L Vargová, L Tao
1Department of Neuroscience, Second Faculty of Medicine, Charles University, and Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic.
Biophysical Journal
|February 13, 2001
Summary
Synthetic poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) polymers can diffuse through the brain's extracellular space. Polymer size influences diffusion, with larger, conjugated polymers showing increased tortuosity, impacting drug delivery strategies.
Area of Science:
- Neuroscience
- Polymer Science
- Biomedical Engineering
Background:
- Understanding diffusion in the brain extracellular space is crucial for drug delivery.
- Polymeric materials are being explored for targeted therapies, necessitating knowledge of their transport properties.
Purpose of the Study:
- To investigate the diffusion characteristics of synthetic poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) polymers in rat neocortical tissue.
- To determine how polymer size and conjugation affect diffusion tortuosity in the brain extracellular matrix.
Main Methods:
- Integrative optical imaging was employed to track the diffusion of PHPMA polymers.
- Diffusion coefficients were measured for various molecular weights of PHPMA (7.8–1057 kDa) in rat neocortical slices.
- Tortuosity was calculated and compared between unconjugated PHPMA, BSA-conjugated PHPMA, and other macromolecules like BSA and dextran.
Main Results:
- PHPMA polymers demonstrated diffusion through the extracellular space of rat neocortical slices.
- The measured tortuosity for PHPMA polymers averaged 1.57, comparable to small molecules.
- Conjugating PHPMA with bovine serum albumin (BSA) significantly increased tortuosity to 2.27, similar to BSA alone.
Conclusions:
- Synthetic PHPMA polymers can navigate the brain's extracellular environment.
- Polymer size and conjugation significantly influence diffusion tortuosity, a key factor for designing brain-penetrant therapeutics.
- The findings support the use of optical imaging and diffusion modeling for characterizing macromolecular transport in neural tissue.