Evidence of superdiffusive nanoscale motion in anionic polymeric hydrogels: Analysis of PGSE- NMR data and comparison with drug release properties

Abstract

Polymeric hydrogels are promising candidates for drug delivery applications, thanks to their ability to encapsulate, transport and release a wide range of chemicals. The successful application of these materials requires a deep understanding of the mechanisms governing solute transport at the nanoscale and its impact on release kinetics. In this work, we investigate the translational diffusion of ibuprofen loaded in anionic agarose-carbomer (AC) hydrogels by 1 H high resolution magic angle spinning (HR-MAS) NMR spectroscopy, and compare it to its macroscopic release kinetics. The analysis of the experimental NMR data provides the first evidence of superdiffusion for ibuprofen in AC hydrogels. Superdiffusive transport is observed in the majority of our samples, especially those with the smallest mesh size (7 nm) and highest ibuprofen concentrations (90-120 mg/mL). This outcome is rationalized in terms of heavy-tailed distributions of spatial displacements (Lèvy flights) and of waiting times, which depend on the nanoscopic structural heterogeneity of the gels and the strong but reversible association between ibuprofen and the agarose matrix.

Hydrogels as Drug Delivery Systems: A Review of Current Characterization and Evaluation Techniques

“…The method investigates the translational molecular motion during drug diffusion to effectively provide the drug coefficient D in m 2 /s for hydrogels [38]. The technique is based on the application of magnetic pulsed-field gradients that encode and decode the molecular mean-square displacement along the gradient direction [70]. The diffusion of ibuprofen, a well-known anti-inflammatory drug, through a 2,2,6,6-tetramethylpiperidine 1-oxyl-oxidized and cellulose nanofiber hydrogel, was measured by high-resolution magic angle spinning (HR-MAS) using the pulsed field gradient spin-echo (PGSE) NMR approach.…”

TEMPO-Nanocellulose/Ca2+ Hydrogels: Ibuprofen Drug Diffusion and In Vitro Cytocompatibility

“…This experimental set-up averages the anisotropic interactions (dipole-dipole interactions and chemical shift anisotropy), leading to well-resolved spectra even for small molecules entrapped in a gel matrix. This methodology opens the possibility to study the diffusion motion of drugs loaded onto heterogeneous gel-like systems and to evaluate in depth the motion regime of the drug in the polymeric gel, including the detection of non-fickian diffusion regimes and related anomalous diffusion behaviours [44,54].…”

“…In a first step, we investigated the modification of the rheological properties of the hydrogels with the TOUS-CNFs content and Ca 2+ concentration, in order to identify the formulation with the ideal elastic properties to be used for the delivery of drugs. Once the hydrogel was selected, we studied the diffusion into the system of a model drug (ibuprofen (IB), an anti-inflammatory drug often employed as model in drug release studies [4,29,44]), used both as pure molecule and as 1:1 complex with β-Cyclodextrins (β-CD) to slow down the drug path. These measures were conducted by diffusion-nuclear magnetic resonance (NMR) spectroscopy methods [45] combined with a high-resolution magic angle spinning (HR-MAS) setup to obtain high resolution data.…”

Antimicrobial materials produced by incorporating copper acetate into ethylene-vinyl alcohol copolymer for its use in personal care and cosmetic packaging

“…Modeling by first Fickian law. The first Fick Law [38][39][40][41] is a common and simple model to express the release behavior of polymer materials. The kinetics of copper (II) acetate release at room temperature was analyzed by the semiempirical equation M t /M o = Kt n and for M t /M o inferior to 0.6.…”