Theoretical Importance of PVP-Alginate Hydrogels Structure on Drug Release Kinetics

Abstract

Background: The new concepts of personalized and precision medicine require the design of more and more refined delivery systems. In this frame, hydrogels can play a very important role as they represent the best surrogate of soft living tissues for what concerns rheological properties. Thus, this paper focusses on a global theoretical approach able to describe how hydrogel polymeric networks can affect the release kinetics of drugs characterized by different sizes. The attention is focused on a case study dealing with an interpenetrated hydrogel made up by alginate and poly(N-vinyl-2-pyrrolidone). Methods: Information about polymeric network characteristics (mesh size distribution and polymer volume fraction) is deduced from the theoretical interpretation of the rheological and the low field Nuclear Magnetic Resonance (NMR) characterization of hydrogels. This information is then, embodied in the mass balance equation whose resolution provides the release kinetics. Results: Our simulations indicate the influence of network characteristics on release kinetics. In addition, the reliability of the proposed approach is supported by the comparison of the model outcome with experimental release data. Conclusions: This study underlines the necessity of a global theoretical approach in order to design reliable delivery systems based on hydrogels.

Combined use of rheology and portable low-field NMR in cystic fibrosis patients

“…the stress sweep, frequency sweep and steady value test. While stress sweep tests serve to detect the maximum deformation the sample can undergo without altering its internal micro-nano-structure, frequency sweep tests determine how much the elastic (G ′ ) and viscous (G ′′ ) properties (moduli) of the sample depend on solicitation pulsation ω. Relying on G ′ and G ′′ knowledge, the shear modulus G of the sample was determined as previously described [25,26] and as detailed in supporting information S1. Then, knowing G, Flory theory [22] and the equivalent network theory [27] allow to evaluate the average mesh size ξ of the polymeric network pervading CF sputum as explained in supporting information S1.…”

“…2, relate to three representative samples and show the gel-like nature (or incipient gel nature) of our samples. Indeed, the data show that the elastic component (G ′ ) prevailed over the viscous one (G ′′ ) and both G' -G ′′ were almost independent of pulsation ω [25,26].…”

Designing Advanced Drug Delivery Systems: Core-Shell Alginate Particles through Electro-Fluid Dynamic Atomization

“…Then, to calculate the effective diffusivity value in the hydrogel, Equation (6) from the Lustig–Peppa model can be used [ 56 ]. In this model, the effective diffusivity is calculated from a corrective factor with respect to the diffusivity in the medium.…”

Effect of chest physiotherapy on cystic fibrosis sputum nanostructure: an experimental and theoretical approach

“…This perfectly matches with G and T 2m increase, as T 2m rises with the decrease of the ratio between the solid (fibres) surface ( S ) in contact with water molecules and the hydrogel water molecule volume ( V ) as per Eq. ( 10 ) [ 22 , 54 ].

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“…The n R determination was performed according to a statistical procedure, in order to minimize the product N * 2 , where N indicates the number of fitting parameters and 2 is the sum of the squared errors [ 21 ]). The sample shear modulus G was evaluated as the sum of all g i ( G = g i ) [ 22 ]. Therefore, Flory theory [ 23 ] allows to evaluate the polymeric network crosslink density, x , defined as the moles of junction points between different polymeric chains per hydrogel unit volume, based on previous G determination: where R is the universal gas constant and T is the absolute temperature.…”