Fabrication And Characterization Of Nanoscale Chitosan-polyphenol-iron Fortificants

Iron fortification of food is a sustainable and cost-effective strategy to reduce iron deficiency anemia.Traditional iron nutrition fortification suffers from problems such as poor stability and high possibility of causing adverse sensory changes.In recent years,nanoscale iron fortification has received extensive attention due to their high bioavailability.Despite the advance in improving its properties,nanostructured iron still suffer from the low stability,where it is easily to oxidize in the solution and tends to aggregate and form a precipitate.In addition,the preparation of nano-sized reduced iron nutrient fortification mostly uses NaBH₄ as a reducing agent.NaBH₄ has potentiality of carcinogenic and mutagenic effects.Chitosan?CS?is a natural nontoxic biopolymer produced.CS has great stability,biocompatibility,non-toxicity and multi-functional properties.On the other hand,plant polyphenols have strong reducing and free radical scavenging activities and are excellent source of antioxidants.In this study,a nano-scale chitosan-polyphenol-iron nutrient enhancer was prepared by using CS as a carrier and stabilizer and natural plant polyphenol as a reducing agent to improve iron's stability and safety.To this end,this study first attempted to use CS as a nano-iron stabilizer and NaBH₄ as a reducing agent as a classical method to study its preparation process and stability,and then natural polyphenols were investigated and used as reducing agents to replace NaBH₄.Iron nanoparticles were intensively characterized,and the main results were as follows:?1?CS-NaBH₄-Fe nanoparticles?NPs?were prepared using CS as a carrier and a stabilizer and NaBH₄ as a reducing agent.The optimal preparing parameters were:chitosan concentration 1.0 mg/mL,FeCl₃ concentration 0.08 mol/L,and NaBH₄ concentration 1.2 mg/mL.Under the optimal conditions,the as prepared CS-NaBH₄-Fe NPs were measured by UV spectroscopy to determine the distribution ratio of Fe???and Fe???to 0.81:1.Fe???and Fe???were also studied by XPS.When the distribution ratio of Fe???was 1.18:1,indicated that CS-NaBH₄-Fe NPs contain a high concentration of Fe?II?.Ultraviolet and infrared spectroscopy analysis showed that CS participates in the construction of CS-NaBH₄-Fe NPs by means of coordination reaction with FeCl₃.The morphology,CS valence distribution,stability and in vitro release of nano-iron of CS-NaBH₄-Fe NPs were investigated.The results showed that the morphology of CS-NaBH₄-Fe NPs solution did not change significantly after being placed at room temperature for two weeks.And it has good valence stability.The thermal decomposition temperature of CS-NaBH₄-Fe NPs freeze-dried powder is about 150?,which indicated that the thermal stability of iron nanoparticles was significantly improved after using chitosan as a support.In vitro simulated gastrointestinal environment,CS-NaBH₄-Fe NPs has shown efficient stable release,ensuring the effective release of Fe???and stability of Fe???and total iron.?2?When CS-polyphenol-Fe NPs were prepared using polyphenols instead of NaBH₄ with natural as reducing agent.Selection of epigallocatechin,epigallocatechin gallate,epicatechin,gallic acid,protocatechuic acid,protocatechuic aldehyde,chlorogenic acid,rosmarinic acid,ten natural polyphenols such as caffeic acid and tea polyphenols are candidate reducing agents.The nanoparticle morphology uniformity,ferrous iron content and solution color were used as comprehensive indicators to optimize the determination of epigallocatechin.EGC was found to be the best reducing agent to prepare CS-EGC-Fe NPs.The CS-EGC-Fe NPs solution has shown good dispensability and transparent brownish yellow.TEM examination showed that CS-EGC-Fe NPs were uniformly dispersed spherical particles.DLS analysis showed an average particle size of 136.2±12.7 nm.Ultraviolet and infrared spectroscopy analysis showed that CS and EGC interact with FeCl₃ to form iron nanoparticles.The morphology,CS valence distribution,stability and in vitro release Release of nanoparticles of CS-EGC-Fe NPs were investigated.The results showed that after the CS-EGC-Fe NPs solution was placed for two weeks,the average particle size,dispensability index and iron valence distribution showed significant changes?p<0.05?,but the particle sizes were still at the nanometer level from 132.3 nm to 158.4 nm),with insignificant change.The lyophilized powder of CS-EGC-Fe NPs has a thermal decomposition temperature of about 173.0?,showing good thermal stability.Simulated in vitro experiments showed that CS-EGC-Fe NPs also had sustained release in gastric and intestinal fluids,and CS-EGC-Fe NPs in the intestinal fluid were mostly in the form of divalent iron,highly dispersed and stable.In summary,the iron nanoparticles prepared by using chitosan as a carrier and a stabilizer and epigallocatechin as a reducing agent have revealed stable morphology,valence distribution and thermal stability.Preliminary studies show that CS-EGC-Fe NPs have sustained release and high-efficiency release in gastric and intestinal fluids in simulated in vitro release experiments.This study provides an environmentally friendly,and low-cost preparation method for preparing nano-scale iron nutrition fortification,which could greatly improve the stability of nano-scale iron nutrition enhancers.