Transport Properties of Self-Assembling G-Hydrogels: Evidence for a Tunable Fickian Diffusivity

• DOI: 10.1021/acs.jpcb.5c00564
• Publication Date: 2025-05-16T03:42:41Z
• Authors: Alessia Pepe; Paolo Moretti; Paolo Mariani; Valentina Notarst...; Francesca Ripanti
• Keywords: Constant (computer programming)

The mixing of Guanosine (Gua) and 5'-monophosphate (GMP) in water selected compositions yields highly hydrated, transparent, self-healing self-assembled supramolecular G-hydrogels, attractive for biomedical applications. This work investigates how hydrogel composition affects solute transport, including diffusion, binding, loading, release properties, using a set fluorescent probes with varying size polarity. Although small/wide-angle X-ray scattering techniques showed that no structural changes are induced by probe addition, even when intercalation into G-quadruplexes is expected, the internal mesh structure hydrogel, modulated Gua:GMP ratio, directly impacts diffusivity loading. Tighter networks (e.g., 1:1) slow diffusion enhance retention compared to looser configurations 1:4). Moreover, UV-visible titrations revealed markedly different binding affinities (Kb ≈ 5.7 × 104 M-1 DAPI, 8.0 103 ThT, 1.4 102 RhB), which expected result lower coefficients slower release, especially DAPI ThT. Indeed, coefficients, obtained via fluorescence recovery after photobleaching time-resolved spectroscopy, reach 90, 20, 60 μm2/s FITC-dextran, RhB, respectively. Probe kinetics, modeled Weibull fitting, indicated sustained characteristic times (τ) between 9.6 23.2 h β 1 1× PBS, consistent predominantly Fickian diffusion. Remarkably, switching 10× PBS significantly accelerated (τ reduced 40-50%), suggesting ionic strength and/or pH critically affect not only probe-hydrogel interactions but also gel architecture, altering porosity, size, network tortuosity, thus enhancing molecular mobility. Overall, G-hydrogel system offers structurally tunable composition-dependent platform capable finely regulating transport profiles, making it suitable controlled drug delivery adaptive biomaterial