Biotechnologically produced chitosans with nonrandom acetylation patterns differ from conventional chitosans in properties and activities

Abstract

Chitosans are versatile biopolymers with multiple biological activities and potential applications. They are linear copolymers of glucosamine and N-acetylglucosamine defined by their degree of polymerisation (DP), fraction of acetylation (FA), and pattern of acetylation (PA). Technical chitosans produced chemically from chitin possess defined DP and FA but random PA, while enzymatically produced natural chitosans probably have non-random PA. This natural process has not been replicated using biotechnology because chitin de-N-acetylases do not efficiently deacetylate crystalline chitin. Here, we show that such enzymes can partially N-acetylate fully deacetylated chitosan in the presence of excess acetate, yielding chitosans with FA up to 0.7 and an enzyme-dependent non-random PA. The biotech chitosans differ from technical chitosans both in terms of physicochemical and nanoscale solution properties and biological activities. As with synthetic block co-polymers, controlling the distribution of building blocks within the biopolymer chain will open a new dimension of chitosan research and exploitation.

Chitosan and Chitosan Nanoparticles: Parameters Enhancing Antifungal Activity

“…In consequence, there is still a small amount of data on how PA affects the biological activity of CS. Recently developed methods of enzymatic deacetylation of chitin open new possibilities to obtain chitosans with specified, nonrandom PA [ 59 ]. One of the first article in this field, by Sreekumar, et al [ 59 ], shown that enzymatically obtained chitosan with block-PA (DD 67%, DP 800) had different physicochemical characteristics compared to chemically obtained chitosan with random-PA (DD 66%, DP 700).…”

“…Recently developed methods of enzymatic deacetylation of chitin open new possibilities to obtain chitosans with specified, nonrandom PA [ 59 ]. One of the first article in this field, by Sreekumar, et al [ 59 ], shown that enzymatically obtained chitosan with block-PA (DD 67%, DP 800) had different physicochemical characteristics compared to chemically obtained chitosan with random-PA (DD 66%, DP 700). They found that, water solution of block-PA chitosan had lower viscosity than that of random-PA chitosan.…”

“…Testing different CS samples with block-PA, the authors reported stronger antibacterial activity of samples with bigger DD values. As they discussed, this was the result of higher charge density of the molecules, stronger electrostatic interactions between GlcN-rich blocks with membrane components, and, in consequence, more evident disruption of cell integrity [ 59 ]. Similar effect concerning antifungal activities of CSs with random PA, reported in many articles, was discussed earlier.…”

“…Two main parameters of CSNPs, that is particle size and zeta potential, can be further adjusted to obtain a homogeneous suspension with desired characteristics [ 74 , 75 ]. As reported in many articles, relatively small modifications at any stage of nanoparticle preparation, as well as the characteristics of the original CS sample (MW, DD, PA) affect the parameters and biological properties of obtained nanoparticles [ 40 , 59 , 73 ]. Depending on the physicochemical properties of the initial chitosan sample and the method of nanoparticle formation, their size ranged from 40 to 600 nm and the zeta potential was from 16 to 54 mV.…”

Biocompatibility of Membranes Based on a Mixture of Chitosan and Lythri herba Aqueous Extract

“…Chitosan, a biopolymeric macromolecule, possesses a multitude of technical and biological properties that have gained significant attention in diverse global research, in particular concerning biomedical healing applications that require anti-microbial and antiinflammatory capacities [30][31][32][33][34][35][36]. At the same time, attractive aspects were analyzed for various fields in the food, cosmetic, medical and pharmaceutical industries, such as the abundant availability and low cost of chitosan, which falls within the general desideratum of obtaining materials through renewable green resources [37,38].…”