Synthesis,Physicochemical Characteristics And Bioactivity Of Selenium Nanosystem Stablized By Chitosan

The red nano selenium has gained more attention because of its excellent bioactivity and low toxicity,but it also tranforms into a dark or grey analogue that is thermodynamically stable,but biologically inert.By now,many efforts have been made to stabilize the red nano selenium including the use of proteins,polysaccharides,polyohenols,and other molecules to prepare stable and uniform selenium nanoparticles.Howerver,there were still some problems such as energy-intensive processes,easily agglomerated in acid pH,rigorous storage conditions,and thermo-unsteadiness,made it hard to use as supplemental dairy selenium.Chitosan,the only positively charged natural polysaccharide,is not only found widely,biocompatible and nontoxic,but also can withstand pepsin and pancreatitn to a great extent.And it has been widely explored as a multifunctional nano carrier by far.In this work,selenium nanosystems stabilized by chitosan were synthesised.First,presise control of the biochemical characterics was studied systemicly,and also the factors.Then the bioactivitives and toxicity were evaluated successively.In one word,the study was aimed to try to provide a green,efficient and low toxicity supplymental selenium product could be used by oral or transdermal.Results are as follow:Both selenium nanoparticle syestems stabilized with chitosan of 3KD nd 300KD were uniform red colloidal sol.The CS(l)-SeNps and CS(h)-SeNps systems would exhibited "core-shell" and"multi-core-shell" microstructures with a size of about 100 nm after 30 day growing through the"bottom-up" and "top-down" approaches,respectively.Both CS-SeNps processed excellent stability towards pH and enzyme treatment.In contrast,selenium was easily released from CS-SeNps upon treatment with different free radicals.Unifrom and long-term stable SeNps system could be manufactured by using chitosan with any Mw(3-600KD),but the growth approach was Mw-dependent.The cost-saving method of CS-SeNps systhesis was using 0.1 mg/mL CS,2 mM SeO32-and 6 mM Vc.And the amounts of raw materials could be amplified 10 fold in equal proportion in atucal production.The medium stability of CS-SeNps was releated to the Mw of CS.The CS-SeNps with lower Mw chitosan,3KDa,had poor stability towards pH?iron strength and thermo treatments,while the 300KCS-SeNps was good.The suitable medium's range of pH was 2-7 for 3KCS-SeNps,and 2-10 for 65KCS-SeNps and 300KCS-SeNps.The size diameter of all CS-SeNps systems could be maintained below 150 nm with variouse iron strengthes(0-0.4 M,pH=3)treatment.Additonaly,the excellent thermo stabilities of 65KCS-SeNps and 300KCS-SeNps made them suiable for variouse hot working technologies.But 3KCS-SeNps only held a better throm stability with 80 ? treatment.Additionly,CS-SeNps processed excellent environment stalities treated with various amonts of humic acid(0-10 mg/L).And this profile had relationship with the Mw of chitosan to some extent.Specifically,the higer Mw of chitosan of CS-SeNps,the stronger ablitiy resisted to a higher concentration of HA,but in contrast,the less amount of HA would be needed to induce some changes of size and zeta potential.CS-SeNps processed excellent saveing free radical abilities,especially to ABTS.And the in vitro antioxidant abilities could be enhanced by a 30-day storage process.Furtermore,the bioactivies of fair transdermal Se delivery efficiency,inhibiting ROS accumulation in BABLC-3T3 and Caco-2 cell lines,preventing damages induced by UV radiation and aging induced by D-galatose in mice model of CS-SeNps were demonstrated.The acute toxicity of CS(1)-SeNPs was ten fold lower than that of H2SeO3.