Multivalent Ions as Reactive Crosslinkers for Biopolymers—A Review

Abstract

Many biopolymers exhibit a strong complexing ability for multivalent ions. Often such ions form ionic bridges between the polymer chains. This leads to the formation of ionic cross linked networks and supermolecular structures, thus promoting the modification of the behavior of solid and gel polymer networks. Sorption of biopolymers on fiber surfaces and interfaces increases substantially in the case of multivalent ions, e.g., calcium being available for ionic crosslinking. Through controlled adsorption and ionic crosslinking surface modification of textile fibers with biopolymers can be achieved, thus altering the characteristics at the interface between fiber and surrounding matrices. A brief introduction on the differences deriving from the biopolymers, as their interaction with other compounds, is given. Functional models are presented and specified by several examples from previous and recent studies. The relevance of ionic crosslinks in biopolymers is discussed by means of selected examples of wider use.

Chemical Modification of Agro-Industrial Waste-Based Bioadsorbents for Enhanced Removal of Zn(II) Ions from Aqueous Solutions

“…The ion exchange could cause the increase of the bands between 1000 and 1700 and around 3000 cm −1 , this is probably because zinc is heavier than calcium. Similar behavior was observed in a research in which pectinate gels were modified with calcium and zinc ions [ 85 , 89 , 90 ]. On the other hand, the higher content of cellulose in the banana and orange bio-adsorbents (see Table 1 ) could be accounted for their better removal performance with respect to granadilla adsorbent [ 34 ].…”

A Chitosan–Agarose Polysaccharide-Based Hydrogel for Biomimetic Remineralization of Dental Enamel

“…The formation and growing of HAP on the acid-etched enamels in the A-and CS-A-sets of samples is rather different due to the functional groups (OH) of agarose and chitosan (NH 2 ), which are respectively involved in the remineralization processes. Chitosan and agarose are marine polysaccharides derivate biopolymers, which aggregate and gel differently in ionic solutions [66][67][68][69]. This behavior could be attributed to the competition between OH and NH 2 groups in forming Ca 2+ clusters of different stability.…”

Effects of Ionic Liquids on Metalloproteins

“…Examples include the structural bridging of alginate chains by Ca 2+ [ 20 ], Mg 2+ bridging and charge stabilization of the bacterial lipopolysaccharides [ 21 ], stabilization and structural modification of DNA and RNA by numerous monovalent and divalent cations [ 21 , 22 , 23 ], and metal-mediated catalysis by nucleic acids [ 24 , 25 ]. For readers interested in a comprehensive review of metal ion interactions with biomolecules, we suggest the recent reviews by Shchreiber and coworkers and/or by Bechtold and coworkers [ 26 , 27 ].…”