A crosslinked system from Scleroglucan derivative: preparation and characterization
Introduction
Scleroglucan is a general term used to designate a class of glucans produced by fungi, especially those of the genus Sclerotium. The commercial product, termed scleroglucan, is water soluble and consists of linearly linked (1→3) β d-glucose residues with (1→6) β d-glucose residues as side chains, one for every three consecutive glucose units. This polysaccharide is dispersed as a triple helix in water, whereas it is dissolved as a single coil in methylsulfoxide [1], [2], [3]. Because of its interesting rheological properties and its resistance to hydrolysis, scleroglucan has general industrial applications. As far as the pharmaceutical field is concerned, experiments performed in vitro indicate that scleroglucan is a polysaccharide suitable for sustained release formulations. In fact, it has been proposed for the formulation of monolithic swellable matrices [4], [5], [6], [7], [8] as well as for ophtalmic preparations [9]; furthermore, oxidized scleroglucan (sclerox) was proposed for a pH-controlled delivery from oral dosage forms [10], [11].
In a previous paper [12] we have shown a part of our studies on a new type of hydrogel obtained by a crosslinking reaction between sclerox and an alkane dihalide. One of the samples has been tested as a matrix for oral dosage forms. The release profiles of a model drug from the tablets prepared with this new hydrogel evidenced a sustained release. The hydrogel was also prepared as a film that was tested as a membrane capable of regulating the diffusion of active substances. We report here further studies on such promising crosslinked hydrogel concerning its characterization, in terms of water uptake and permeation experiments. A theoretical analysis of permeation experiments allows to calculate the diffusion coefficient of theophylline, used as a model drug. The swelling equilibrium data of hydrogels, collected at two different ionic strengths, are analyzed applying a strategy, based on the Flory–Rehner theory, to estimate the crosslink density ρx of the polymer.
The swelling kinetics curves are studied applying a recently proposed theoretical approach from which it is also possible to estimate the diffusion coefficient of the solvent molecule inside the polymeric systems. An estimation of the mesh size of the hydrogel at the highest degree of crosslinking, in terms of molecular weight cut-off, is obtained by means of permeation experiments carried out with polystyrene sulphonate-sodium salt at different molecular weights.
Section snippets
Materials
Scleroglucan (Actigum CS 11) was provided by Mero-Rousselot-Satia (France). Theophylline (TPH) and NaCl were Carlo Erba products (Italy); the polystyrene sulphonate-sodium salt (PSS) of narrow molecular weight distribution (calibration kit, Mw/Mn=1.10) was purchased from Polymer Laboratories (UK). Methylsulfoxide GR dried (DMSO), used as a medium for the crosslinking reaction, was purchased from Merck (Germany). All other products and reagents were of analytical grade; distilled water was
Swelling
In Fig. 2 the relative increase of weight [(W−W0)/W0] as a function of time is reported at two different temperatures (7 and 37°C) and at two r values (0.5 and 1.0). It is possible to observe that for both crosslinked polymers the increase of weight in water was not appreciably influenced by temperature variations while, as expected, it was noticeably affected by the degree of crosslinking.
The effect of environmental ionic strength on solvent uptake is reported in Fig. 3. As it is possible to
Conclusion
Reported results on the behavior of the crosslinked sclerox indicate that these new derivatives show a very high degree of swelling in water that, in the case of r=0.5, can be reduced if salt is added to the surrounding medium. The study of the swelling equilibrium in different ionic strength gives an estimation for the crosslinking density at different r values. An uncommon strategy approach to analyze the swelling kinetics has been applied obtaining a very good agreement with the experimental
Acknowledgements
This work was carried out with the financial support of C.N.R. and MURST.
References (43)
- et al.
Physicochemical characterization and tableting properties of Scleroglucan
Int J Pharm
(1994) - et al.
Investigation of the features of Scleroglucan, a polysaccharide of fungin origin, as a vehicle for ocular topical administration
Pharmacol Res
(1993) - et al.
Novel hydrogel system from a scleroglucansynthesis and characterization
J Control Rel
(1999) - et al.
Solution properties of a new polyelectrolyte derived from the polysaccharide Scleroglucan
Carbohydr Polym
(1983) - et al.
Synthesis and preliminary characterization of new esters of the bacterial polysaccharide gellan
Carbohydr Res
(1992) - et al.
Thermodynamics of hydrogen-bonded polymer gel–solvent systems
Chem Eng Sci
(1995) - et al.
Modeling phase transitions and sorption-desorption kinetics in thermo-sensitive gels for controlled drug delivery systems
Fluid Phase Equilib
(1996) - et al.
A combination of vapor sorption and laser light scattering methods for the determination of the Flory parameter χ and the crosslink density of a polymeric microgel
Fluid Phase Equilib
(2000) - et al.
Continuum thermodynamics and transport theory for polymer–fluid mixtures
Chem Eng Sci
(1992) - et al.
Drug release from an ensemble of swellable crosslinked polymer particles
J Control Rel
(2000)
Mathematical modeling of drug release from hydrogel matrices via a diffusion coupled with desorption mechanism
J Control Rel
Mathematical modelling of drug permeation through a swollen membrane
J Control Rel
Triple helix of a Schizophyllum commune polysaccahride in aqueous solution
J Polym Sci Polym Phys Ed
Triple helix of Schizophyllum commune polysaccahride in dilute solution
3. Hydrodynamic properties in water. Macromolecules
Triple helix of Schizophyllum commune polysaccahride in dilute solution
5. Light scattering and refractometry in mixtures of water and dimethyl sulfoxide. Macromolecules
Scleroglucan sustained release oral preparations
Part I. In vitro experiments. Drug Des Delivery
Studies on the release behaviour of a polysaccharide matrix
Pharmazie
Scleroglucan sustained release oral preparations
Part II. Effects of additives. Drug Des Delivery
Release from a polysaccharide matrixeffect of the molecular weight of the drug
Acta Technol Legis Med
A possible pH-controlled drug delivery system based on a derivative of the polysaccharide Scleroglucan
J Pharm Pharmacol
Environmental effects on the delivery of drugs from a pH-sensitive matrix
Acta Technol Legis Med
Cited by (41)
Rubber elasticity of polymer networks in explicitly non-Gaussian states. Statistical mechanics and LF-NMR inquiry in hydrogel systems
2022, International Journal of Engineering ScienceCitation Excerpt :In this paper, we applied it to alginate, agar and scleroglucan hydrogels, that is, three examples of amply used materials for biomedical use and drug release (Matricardi, Alhaique, & Coviello, 2016). It is important to remind the non-Gaussian character we refer to is not associated to a polymeric network approaching its extensibility limit (upon swelling), a condition that requires adopting the inverse Langevin’s function (or more conveniently some approximation of it, as proposed by Warner (Bird, Armstrong, & Hassager, 1990)) to model the swelling equilibrium (Coviello, Grassi, Rambone, & Alhaique, 2001). Our focus on the contrary is on the possibility that, just after crosslinking as well, the end-to-end chain distribution function does not follow a Gaussian behavior, this being still one of the main limitations of Flory’s theory, as it was further emphasized quite recently (Richbourg & Peppas, 2020).
Fungal exopolysaccharides: Properties, sources, modifications, and biomedical applications
2022, Carbohydrate PolymersCitation Excerpt :Microbial EPSs yield varies based on the type of the strain and factors such as the conditions of the fermentation parameters such as pH, temperature, etc. (Elsehemy et al., 2020; Okoro, Gholipour et al., 2021; Saadat et al., 2021; Shanmugam & Abirami, 2019). While bacteria and fungi are the most common sources of microbial EPSs (Barcelos et al., 2020b; Hamidi, Gholipour, et al., 2020; Hamidi, Kozani, et al., 2020; Mahapatra & Banerjee, 2013a; Saadat et al., 2021), fungal EPSs have received less attention (Coviello et al., 2001; Mahapatra & Banerjee, 2013a; Mahapatra & Banerjee, 2013c). Recognizing the importance and benefits of fungal EPSs (Fig. 1A), the present work will present a comprehensive literature review, with an emphasis on studies published in the last decade and explore fungal EPSs production and their potential for biomedical applications such as anti-inflammatory effects (Barbieri et al., 2017; Rajasekar et al., 2008), improvement of the immune system (Rajasekar et al., 2008; Zhao et al., 2018), anticancer actions (Barbieri et al., 2017; Mahapatra & Banerjee, 2013a; Mahapatra & Banerjee, 2013c; Rajasekar et al., 2008; Zhao et al., 2018) influence on the cardiovascular system (Mahapatra & Banerjee, 2013a; Mahapatra & Banerjee, 2013c; Rajasekar et al., 2008), and treatment of hypercholesterolemia and diabetes (Asadi et al., 2021; Mahapatra & Banerjee, 2013a; Mahapatra & Banerjee, 2013c; Rajasekar et al., 2008).
Natural polysaccharides
2019, Natural Polysaccharides in Drug Delivery and Biomedical ApplicationsConformation of carboxylated schizophyllan in aqueous solution
2015, Carbohydrate PolymersCrosslinked ionic polysaccharides for stimuli-sensitive drug delivery
2013, Advanced Drug Delivery ReviewsCitation Excerpt :Similar results were reported for scleroglucan crosslinked with 1,6-hexanedibromide. The presence of the salt in the medium led to the shrinking of the network and, although the interaction between the COO− groups of scleroglucan and theophylline became weaker, a significant decrease in the drug release was observed [117,118]. The nonionic polysaccharide guar gum that can be modified with anionic and cationic substituents to obtain pH-sensitive release [53,119,120].