Quantification of alginate by aggregation induced by calcium ions and fluorescent polycations

Zheng, Hewen; Korendovych, Ivan V.; Luk, Yan Yeung

doi:10.1016/j.ab.2015.09.016

Cited by 9 publications

(8 citation statements)

References 29 publications

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“…The alginate content in the prepared CA matrices was measured by a previously reported carbazole method with some modifications. , In brief, the collagen and the representative CA matrix were obtained by incubating the prepared precursors (the final collagen concentration was 5 mg mL –1 ) at 37 °C for 24 h. After a 48 h rinsing with deionized water, the corresponding hydrogels were lyophilized. The obtained collagen and CA matrix were weighed and then swollen in 1 mL of deionized water in a glass tube at 37 °C overnight.…”

Section: Methodsmentioning

confidence: 99%

Micro-/Nanomechanics Dependence of Biomimetic Matrices upon Collagen-Based Fibrillar Aggregation and Arrangement

Ran

et al. 2020

Biomacromolecules

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The mechanical and morphological cues of fibrillar extracellular matrices (ECMs) play vital roles in controlling the cellular behaviors. Understanding and regulating the correlation of the mechanics with morphologies, at the micro-/nanoscale are of great relevance to guide the growth and differentiation of stem or progenitor cells into the desired tissues. However, the investigations directed toward acquiring such a kind of correlation are very limited and far from satisfactory. Here, rheological and nanoindentation tests were employed to appraise the mechanical behaviors of biomimetic ECMs assembled from type I collagen solutions containing the equivalent content of alginate but with different molecular weights (MWs). An alginate-molecular-weightdependent trend was found in the fibrillogenesis process and the fibril aggregation of these collagen−alginate (CA) matrices. The present study revealed that the viscoelasticity and nonlinear elasticity of the CA matrices relied upon their specific fibrillar architectures in which a heterogeneous structure formed with varying alginate MW, including the coexistence of small fibrils and larger fibrillar bundles. The correlation of the mechanical behaviors with the inhomogeneity in the fibrillar structures was further discussed in combination with those of Ca 2+ ionically cross-linked CA matrices. This study not only presented the delicate mechanics of fibrillar ECM analogues but also showed that the introduction of affiliative matters such as polysaccharides (alginate with different MWs) is a simple and convenient strategy to achieve biomimetic hydrogels with tunable viscoelastic properties.

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Section: Methodsmentioning

confidence: 99%

Micro-/Nanomechanics Dependence of Biomimetic Matrices upon Collagen-Based Fibrillar Aggregation and Arrangement

Ran

et al. 2020

Biomacromolecules

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“…Standards (0–1000 μg/mL) used to extrapolate alginate concentration were constructed from Na‐alginate (Sigma‐Aldrich) in triplicates. Standard curve repeated as described previously [37] …”

Section: Methodsmentioning

confidence: 99%

“…CaCl 2 alginate aggregation assay : Overnight cultures (5 mL) were grown for 24 h (1.0 OD 600 ) at 37 °C, 250 rpm. 1 mL samples were pipetted into 9 mL of 60 mM CaCl 2 solution to visualize formation of alginate hydrogel [37] …”

Section: Methodsmentioning

confidence: 99%

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Exploration of Ligand‐receptor Binding and Mechanisms for Alginate Reduction and Phenotype Reversion by Mucoid Pseudomonas aeruginosa

et al. 2021

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Bacteria in general can develop a wide range of phenotypes under different conditions and external stresses. The phenotypes that reside in biofilms, overproduce exopolymers, and show increased motility often exhibit drug tolerance and drug persistence. In this work, we describe a class of small molecules that delay and inhibit the overproduction of alginate by a non‐swarming mucoid Pseudomonas aeruginosa. Among these molecules, selected benzophenone‐derived alkyl disaccharides cause the mucoid bacteria to swarm on hydrated soft agar gel and revert the mucoid to a nonmucoid phenotype. The sessile (biofilm) and motile (swarming) phenotypes are controlled by opposing signaling pathways with high and low intracellular levels of bis‐(3’,5’)‐cyclic diguanosine monophosphate (cdG), respectively. As our molecules control several of these phenotypes, we explored a protein receptor, pilin of the pili appendages, that is consistent with controlling these bioactivities and signaling pathways. To test this binding hypothesis, we developed a bacterial motility‐enabled binding assay that uses the interfacial properties of hydrated gels and bacterial motility to conduct label‐free ligand‐receptor binding studies. The structure‐activity correlation and receptor identification reveal a plausible mechanism for reverting mucoid to nonmucoid phenotypes by binding pili appendages with ligands capable of sequestering and neutralizing reactive oxygen species.

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“…40 Rinsing experiments with various species such as divalent metals like Ca 2þ might prove interesting given their potential role in conventional hydrogels as cross linkers. [41][42][43] Since these films are able to sequester water and possibly also NaCl from relatively concentrated aqueous salt solutions, the exchange of protons for protons is facile and nondestructive. The exchange of protons for deuterons is also facile and partly reversible, but possibly somewhat destructive of the film's internal structure.…”

Section: Biological Implicationsmentioning

confidence: 99%

Optical interference probe of biofilm hydrology: label-free characterization of the dynamic hydration behavior of native biofilms

et al. 2017

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Biofilm produced by Escherichia coli (E. coli) or Pseudomonas aeruginosa (P. aeruginosa) on quartz or polystyrene is removed from the culture medium and drained. Observed optical interference fringes indicate the presence of a layer of uniform thickness with refractive index different from air-dried biofilm. Fringe wavelengths indicate that layer optical thickness is < 20 ?? ? m or 1 to 2 orders of magnitude thinner than the biofilm as measured by confocal Raman microscopy or fluorescence imaging of the bacteria. Raman shows that films have an alginate-like carbohydrate composition. Fringe amplitudes indicate that the refractive index of the interfering layer is higher than dry alginate. Drying and rehydration nondestructively thins and restores the interfering layer. The strength of the 1451-nm near infrared water absorption varies in unison with thickness. Absorption and layer thickness are proportional for films with different bacteria, substrates, and growth conditions. Formation of the interfering layer is general, possibly depending more on the chemical nature of alginate-like materials than bacterial processes. Films grown during the exponential growth phase produce no observable interference fringes, indicating requirements for layer formation are not met, possibly reflecting bacterial activities at that stage. The interfering layer might provide a protective environment for bacteria when water is scarce.

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Quantification of alginate by aggregation induced by calcium ions and fluorescent polycations

Cited by 9 publications

References 29 publications

Micro-/Nanomechanics Dependence of Biomimetic Matrices upon Collagen-Based Fibrillar Aggregation and Arrangement

Micro-/Nanomechanics Dependence of Biomimetic Matrices upon Collagen-Based Fibrillar Aggregation and Arrangement

Exploration of Ligand‐receptor Binding and Mechanisms for Alginate Reduction and Phenotype Reversion by Mucoid Pseudomonas aeruginosa

Optical interference probe of biofilm hydrology: label-free characterization of the dynamic hydration behavior of native biofilms

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