Microstructural, mechanical and mass transport properties of isotropic and capillary alginate gels

Schuster, Erich; Eckardt, J.; Hermansson, Anne‐Marie; Larsson, Anette; Lorén, Niklas; Altskär, Annika; Ström, Anna

doi:10.1039/c3sm52285g

Cited by 53 publications

(36 citation statements)

References 43 publications

(68 reference statements)

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“…In terms of the formed matrices, a previous transmission electron microscopic study has demonstrated a nano-network architecture formed by calcium alginate similar to the fibrous structures observed in sundew adhesive [41]. However, this architecture is loosely stitched and is not as tight-knit as that obtained in sundew adhesive, comparatively [41].…”

Section: Functional Groups Aiding In the Assembly Of The Nano-networkmentioning

confidence: 95%

Sundew adhesive: a naturally occurring hydrogel

Huang

Wang

Sun

et al. 2015

J. R. Soc. Interface.

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Bioadhesives have drawn increasing interest in recent years, owing to their ecofriendly, biocompatible and biodegradable nature. As a typical bioadhesive, sticky exudate observed on the stalked glands of sundew plants aids in the capture of insects and this viscoelastic adhesive has triggered extensive interests in revealing the implied adhesion mechanisms. Despite the significant progress that has been made, the structural traits of the sundew adhesive, especially the morphological characteristics in nanoscale, which may give rise to the viscous and elastic properties of this mucilage, remain unclear. Here, we show that the sundew adhesive is a naturally occurring hydrogel, consisting of nanonetwork architectures assembled with polysaccharides. The assembly process of the polysaccharides in this hydrogel is proposed to be driven by electrostatic interactions mediated with divalent cations. Negatively charged nanoparticles, with an average diameter of 231.9 + 14.8 nm, are also obtained from this hydrogel and these nanoparticles are presumed to exert vital roles in the assembly of the nano-networks. Further characterization via atomic force microscopy indicates that the stretching deformation of the sundew adhesive is associated with the flexibility of its fibrous architectures. It is also observed that the adhesion strength of the sundew adhesive is susceptible to low temperatures. Both elasticity and adhesion strength of the sundew adhesive reduce in response to lowering the ambient temperature. The feasibility of applying sundew adhesive for tissue engineering is subsequently explored in this study. Results show that the fibrous scaffolds obtained from sundew adhesive are capable of increasing the adhesion of multiple types of cells, including fibroblast cells and smooth muscle cells, a property that results from the enhanced adsorption of serum proteins. In addition, in light of the weak cytotoxic activity exhibited by these scaffolds towards a variety of mammal cells, evidence is sufficient to propose that sundew adhesive is a promising nanomaterial worth further exploitation in the field of tissue engineering.

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Section: Functional Groups Aiding In the Assembly Of The Nano-networkmentioning

confidence: 95%

Sundew adhesive: a naturally occurring hydrogel

Huang

Wang

Sun

et al. 2015

J. R. Soc. Interface.

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“…In conjunction, indirect diffusivity estimations using pore size characterization by various scanning probe microscopy (SPM) methods have been documented [14,15,16]. Other methods include spectrophotometry [17,18,19,20], size exclusion chromatography [8,21], mechanical release tests [22,23] and fluorescence microscopy [23,24,25]. Regardless of the diffusivity characterization method, the following are a sub-set of factors affecting cross-link homogeneity, size and density, gel isotropy and, thus, membrane diffusivity [13,19,20]: (1) the β- d -mannuronic (M) to α- l -guluronic (G) ratio, the distribution of each monomer within the chain, and alginate molecular weight (MW); (2) the kinetics of gelation, specifically external gelation (chelation) vs. internal gelation.…”

Section: Introductionmentioning

confidence: 99%

Fickian-Based Empirical Approach for Diffusivity Determination in Hollow Alginate-Based Microfibers Using 2D Fluorescence Microscopy and Comparison with Theoretical Predictions

Mobed-Miremadi

Djomehri

Keralapura³

et al. 2014

Materials

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Hollow alginate microfibers (od = 1.3 mm, id = 0.9 mm, th = 400 µm, L = 3.5 cm) comprised of 2% (w/v) medium molecular weight alginate cross-linked with 0.9 M CaCl2 were fabricated to model outward diffusion capture by 2D fluorescent microscopy. A two-fold comparison of diffusivity determination based on real-time diffusion of Fluorescein isothiocyanate molecular weight (FITC MW) markers was conducted using a proposed Fickian-based approach in conjunction with a previously established numerical model developed based on spectrophotometric data. Computed empirical/numerical (Dempiricial/Dnumerical) diffusivities characterized by small standard deviations for the 4-, 70- and 500-kDa markers expressed in m2/s are (1.06 × 10−9 ± 1.96 × 10−10)/(2.03 × 10−11), (5.89 × 10−11 ± 2.83 × 10−12)/(4.6 × 10−12) and (4.89 × 10−12 ± 3.94 × 10−13)/(1.27 × 10−12), respectively, with the discrimination between the computation techniques narrowing down as a function of MW. The use of the numerical approach is recommended for fluorescence-based measurements as the standard computational method for effective diffusivity determination until capture rates (minimum 12 fps for the 4-kDa marker) and the use of linear instead of polynomial interpolating functions to model temporal intensity gradients have been proven to minimize the extent of systematic errors associated with the proposed empirical method.

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“…Also, given that the kinetics of binding of chitosan amino groups to xanthan carboxyl groups is fast, inhomogeneous molecular distribution might be somehow expected. Different mass transport mechanisms can be observed in gels and other similar structured materials, such as hydrodynamic flow, capillary flow, and molecular self-diffusion (Hermansson 2008;Schuster et al 2014), depending on their structure. While hydrodynamic flow is observed in large and open structures, being driven by forces such as gravity and differences in chemical potential, capillary flow is noticed in gels with smaller pores and channels.…”

Section: Physico-chemical Characterization Of the Filmsmentioning

confidence: 99%