PhD Scientific Days 2026

Theoretical and Translational Medicine 1.

Investigation of pH-Dependent Swelling of Submicron-Hydrogel Fibrous Membranes

Name of the presenter

Szalai, Donát

Institute/workplace of the presenter

Laboratory of Nanochemistry, Department of Biophysics and Radiation Biology, Semmelweis University

Authors

Donát Szalai¹
1: Laboratory of Nanochemistry, Department of Biophysics and Radiation Biology, Semmelweis University

Text of the abstract

Hydrogels play a pivotal role in modern medicine, ranging from advanced drug delivery systems to tissue regeneration applications. Their promising properties stem from their structure, which resembles that of natural tissues, as well as their sensitive responses to changes in environmental parameters. Electrospinning can be used to create fibrous hydrogel structures whose morphology also resembles the native extracellular matrix. However, our knowledge of their swelling behavior is still limited.
The aim of this research is to characterize the morphology of hydrogel fibrous membranes crosslinked with 1,4-diaminobutane (DAB) based on poly(aspartic acid) (PASPDAB) and to investigate their pH-dependent swelling properties.
Fabrics with different fiber orientations were synthesized from polysuccinimide (PSI) via electrospinning. To prepare PASPDAB hydrogel fibers, we crosslinked PSI with an ethanol solution of DAB and then hydrolyzed it in a pH 8 buffer. The morphology of the samples was examined using a Scanning Electron Microcopy (SEM) and a Confocal Laser Scanning Microscopy (CLSM). Swelling tests were conducted using a pH series ranging from pH 3 to pH 8, and kinetics were studied through repeated pH changes between pH 3 and pH 8. Changes in their size were monitored using a high-resolution camera, and the recorded image data were analyzed using ImageJ software.
Ultimately, I successfully synthesized PSI and PASPDAB fibers, whose morphological structure I verified using SEM and CLSM microscopies. Based on the analysis of the images, the fiber diameters fall within the submicron range (d = 100-1000 nm). Furthermore, CLSM confirms that well-separated, individual fibers remain present in the native sample even after crosslinking. The volume change yields a sigmoidal curve in a logarithmic plot, with an inflection point at a pH of approximately 5.7. According to kinetic studies, the majority of swelling occurs within the first hour (t1/2 < 16 minutes), while the total change in size takes place over 360 minutes.
In summary, these fibrous hydrogels are flexible, suturable, and reproducible alternatives to brittle bulk gels, offering faster, more controlled, and reliable swelling responses suitable for various biomedical applications.
Support was provided by grants TKP2021-EGA-23, NKFIH FK 137749, and NKFIH ADVANCED 150826.