Fractal kinetics in drug release from finite fractal matrices

Kosmidis, Kosmas; Argyrakis, Panos; Macheras, Panos

doi:10.1063/1.1603731

Cited by 144 publications

(101 citation statements)

References 14 publications

(22 reference statements)

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“…The original Kopelman algorithm was given strong theoretical support when it was shown that fractal kinetics owes its emergence to spatial self-organization of the reactants induced by the compact properties of diffusion [102]. Being an extremely significant platform, countless applications of this scheme have been attempted over the years, with a number of these being quite important [103][104][105][106][107]. The interested reader might also benefit from studying the work of Turner et al [103] who carried out an in-depth comparison of various pertinent schemes.…”

Section: Studies In Fractal Kineticsmentioning

confidence: 99%

Fractal symmetry of protein interior: what have we learned?

Banerji

Ghosh

2011

Cell. Mol. Life Sci.

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The application of fractal dimension-based constructs to probe the protein interior dates back to the development of the concept of fractal dimension itself. Numerous approaches have been tried and tested over a course of (almost) 30 years with the aim of elucidating the various facets of symmetry of self-similarity prevalent in the protein interior. In the last 5 years especially, there has been a startling upsurge of research that innovatively stretches the limits of fractal-based studies to present an array of unexpected results on the biophysical properties of protein interior. In this article, we introduce readers to the fundamentals of fractals, reviewing the commonality (and the lack of it) between these approaches before exploring the patterns in the results that they produced. Clustering the approaches in major schools of protein self-similarity studies, we describe the evolution of fractal dimension-based methodologies. The genealogy of approaches (and results) presented here portrays a clear picture of the contemporary state of fractal-based studies in the context of the protein interior. To underline the utility of fractal dimension-based measures further, we have performed a correlation dimension analysis on all of the available non-redundant protein structures, both at the level of an individual protein and at the level of structural domains. In this investigation, we were able to separately quantify the self-similar symmetries in spatial correlation patterns amongst peptide-dipole units, charged amino acids, residues with the π-electron cloud and hydrophobic amino acids. The results revealed that electrostatic environments in the interiors of proteins belonging to 'α/α toroid' (all-α class) and 'PLP-dependent transferase-like' domains (α/β class) are highly conducive. In contrast, the interiors of 'zinc finger design' ('designed proteins') and 'knottins' ('small proteins') were identified as folds with the least conducive electrostatic environments. The fold 'conotoxins' (peptides) could be unambiguously identified as one type with the least stability. The same analyses revealed that peptide-dipoles in the α/β class of proteins, in general, are more correlated to each other than are the peptide-dipoles in proteins belonging to the all-α class. Highly favorable electrostatic milieu in the interiors of TIM-barrel, α/β-hydrolase structures could explain their remarkably conserved (evolutionary) stability from a new light. Finally, we point out certain inherent limitations of fractal constructs before attempting to identify the areas and problems where the implementation of fractal dimension-based constructs can be of paramount help to unearth latent information on protein structural properties.

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Section: Studies In Fractal Kineticsmentioning

confidence: 99%

Fractal symmetry of protein interior: what have we learned?

Banerji

Ghosh

2011

Cell. Mol. Life Sci.

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“…There are, however, two exceptions. The release from the chitosan-coated particles in acidic medium can be associated with drug diffusion in normal Euclidian space (b = 0.7) [15]. The lowest b value was obtained for the bilayer-coated microspheres in pH = 6.8 (b = 0.42) and according to Kosmidis et al [15] in this case the release can be described by the diffusion mechanism in fractal or disordered substrate.…”

Section: Discussionmentioning

confidence: 98%

New bilayer-coated microbead system for controlled release of 5-aminosalicylic acid

2010

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A new bilayer-coated microbeads for oral delivery of 5-aminosalicylic acid (5-ASA) were prepared from naturally occurring polysaccharides via emulsification method. 5-ASA was successfully encapsulated in chitosan-k-carrageenancoated alginate microbeads. The morphology and sizes of microparticles were studied using optical microscopy and dynamic light scattering. Drug release profiles were followed using high-performance liquid chromatography (HPLC) with spectrophotometric detection. The effect of chitosan thin layer and chitosan-k-carrageenan bilayer on the drug release was studied at pH values simulating these characteristic for stomach (pH = 1.2) and intestine (pH = 7.4). Chitosan layer slightly increased 5-ASA release at pH = 1.2, whereas double-layer external coating decreased the release rates. Due to the bilayer properties, the micro-carriers were additionally protected against acidic conditions of the stomach and drug release in the intestine could be better controlled.

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“…It indicated that a linear relationship most likely existed between the logarithm of the amount of drug release and time. Kosmidis et al revealed that the Weibull was one of the most appropriate equation to describe the entire duration of the drug release process, thus providing a more generalized picture [48].…”

Section: In Vitro Releasementioning

confidence: 99%

Development and characterization of a self-double-emulsifying drug delivery system containing both epigallocatechin-3-gallate and α-lipoic acid

Zhao

Xia

et al. 2015

J Mater Sci

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The present study investigated a self-doubleemulsifying drug delivery system (SDEDDS) loaded with epigallocatechin-3-gallate (EGCG) and a-lipoic acid to improve EGCG photostability and possess a sustained release behavior. The long chain solid lipids (cetostearyl alcohol) and macadamia oil were utilized as a carrier to codeliver the two bioactive ingredients. The prepared EA-SDEDDS for topical application was formulated using modified two-step method and characterized by confocal microscopy, in vitro release, and antioxidant effects. EA-SDEDDS was found to be stable under simulated sunlight for 1 month (at room temperature). In vitro cell culture studies, EA-SDEDDS provided protection for 3t3 fibroblasts that underwent H 2 O 2 oxidative stress due to sustained release property. Cellular antioxidant activity assay indicated that EA-SDEDDS showed anti-oxidative capacity with the same efficacy compared to EGCG-a-lipoic acid solution.

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Fractal kinetics in drug release from finite fractal matrices

Cited by 144 publications

References 14 publications

Fractal symmetry of protein interior: what have we learned?

Fractal symmetry of protein interior: what have we learned?

New bilayer-coated microbead system for controlled release of 5-aminosalicylic acid

Development and characterization of a self-double-emulsifying drug delivery system containing both epigallocatechin-3-gallate and α-lipoic acid

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