Modeling of Caffeine Release from Crosslinked Water-Swellable Gelatin and Gelatin-Maltodextrin Hydrogels

Abstract

Research from this group has recently led to the development of a genipin-crosslinked gelatin gel that may be used as a controlled release matrix for bioactive compounds. This study presents a model that simulates the release of entrapped caffeine from the hydrogel and the ingress of water into these gels. Fick's second law Abbreviations: A, Dimensionless front-fixing radius; B, Dimensionless front-fixing height; C 0 , Caffeine concentration at initial conditions in the cylindrical matrix; C 1,eq , Equilibrium water concentration in the fully swollen cylindrical matrix; C 1 , Water concentration in the cylindrical matrix; C 2 , Caffeine concentration in the cylindrical matrix;C 1 , Dimensionless water concentration in the cylindrical matrix; C 2 , Dimensionless caffeine concentration in the cylindrical matrix; D 1 , Water diffusion coefficient in the cylindrical matrix; D 2 , Caffeine diffusion coefficient in the cylindrical matrix; D 1,eq , Diffusion coefficient of caffeine in the fully swollen cylindrical matrix; D 2,eq , Diffusion coefficient of water in the fully swollen cylindrical matrix; r , Radial coordinate in the cylindrical matrix; r 0 , Initial radius of the cylindrical matrix;r , Dimensionless radius of the cylindrical matrix; r N , New radius of the cylindrical matrix; r t , (New radius of the cylindrical matrix)/(initial radius of the cylindrical matrix); t, Time; z, Axial coordinate in the cylindrical matrix; z 0 , Initial half-height of the cylindrical matrix;z, Dimensionless half-height of the cylindrical matrix; z N , New half height of cylindrical matrix; z t , (New half-height of the cylindrical matrix)/(initial half-height of the cylindrical matrix); V p , Dry matrix volume; β 1 , Dimensionless constant for the diffusion of water; β 2 , Dimensionless constant for the diffusion of caffeine; ρ 1 , Density of water; ρ 2 , Density of caffeine; τ , Dimensionless time.of diffusion is used to describe the water penetration and bioactive release in the system. To validate the model, caffeine release experiments from the gel were carried out. The predicted bioactive release profiles are in very good agreement with experimental data at different gel compositions. The model may also be used for a wide range of bioactive molecules and hydrogels with different cylindrical dimensions.

Gelatin Hydrogel Prepared by Photo‐initiated Polymerization and Loaded with TGF‐β1 for Cartilage Tissue Engineering

“…The chemical crosslinkers such as glutaraldehyde and carbodiimide etc, on the other hand, have some extent of cytotoxicity. [17] Recently, less toxic crosslinkers such as transglutaminase [18][19][20] and genipin [21][22][23] have been used to form the gelatin chemical gels. Chemical modification of the gelatin molecule is also performed to result in chemical gels initiated by redox initiators, potassium peroxodisulfate (KPS) and N,N,N 0 ,N 00 -tetramethylethylenediamine (TEMED), for example.…”

Multilevel computations of dispersed drug release

“…Here, we do not use the front‐fixing method, which was proposed by Landau [20] and applied to moving boundary problems in controlled drug release [10, 2]. By introducing a variable η = z / Z (τ), the computational domain is mapped to the unit interval in the front‐fixing method.…”

“…Hence, numerical methods are needed to approximate a solution for the entire release process. Finite element and finite difference methods are usually applied in numerical simulations of the matrix CRS [10, 2, 5]. To obtain a better approximation with lower computational costs, we introduce here a multilevel method to solve the system of diffusion equations numerically.…”

A new proposed approach to estimate the thermodiffusion coefficients for linear chain hydrocarbon binary mixtures

“…In diffusion-limited systems, free volume is the paramount factor in controlling the release rate of molecules. 20 Free volume is generally defined as the volume of a system at a given temperature minus its volume at absolute zero. Rearrangement of the free volume makes pores or voids through which diffusing species may pass.…”

“…22 Pores that are larger than the diffusing molecule will permit diffusion with little or no resistance, whereas diffusing species larger than the pores will encounter resistance against their flow as they become entangled with the matrix mesh. 20 As a result, the required energy for detaching a molecule is directly related to the molecular size and shape. The effect of the molecular size and average mesh size for specific molecules can be shown in the molecular weight and the specific volume of each component.…”