| Nowadays,the understanding of"nano"has gradually deepened towards biological safety with the rapid development of nanotechnology in the food field.In addition to artificially synthesized nanoparticles（NPs）,recent studies showed that a new type of NPs were inevitably produced from food components in thermal process.These NPs produced in the food processing at high temperature were called as endogenous food-borne NPs.Complex physicochemical reactions ocuured during food thermal processing,causing significant changes of food components,thus producing endogoues NPs.However,the systematic studies about the endogenous food-borne NPs are still in an early stage.In this paper,as an economic fish with high protein and low fat,Spanish mackerel was chosen as researed object.The formation of food-borne NPs from roasted mackerel,and their digestion,biological distribution and cytotoxicity were investigated in detail.The properties of NPs from mackerel and their formation mechanism were preliminarily studied.Besides,the interaction between NPs and digestive protease was confirmed.Ihis work provided fundamental research data for the formation mechanism and biological effects of food-borne NPs in roasted mackerel.The main contents and conclusion of this paper are listed as follows:（1）Endogenous NPs were extracted from the mackerel flesh in roasting for 10,20,30 and40 min,respectively,after the moisture in flesh was evaporated.The NPs were easily to be generated when the temperature of fish was higher than 100 oC in the roasted process.The analysis results showed that NPs have near-spherical structure with nuclear,and are mainly composed of amorphous carbon,nitrogen and oxygen elemens with abundant hydrophilic functional groups on the surface.Excitation dependent fluorescence emission behavior was found for the NPs,which have the highest fluorescence quantum yield of 6.89%,with good fluorescence stability.The fluorescence quantum yield,fluorescence lifetime,production yield of the NPs increased with the increase of the roasting time,but their particle size showed a decrese trend.（2）With the increase of roasting time,the fluorescence internsity of NPs decreaed more significantly by digestive juice,and the maximum quenching rate was nearly 8%.The NPs from flesh roasted for 40 min were incubated with pepsin and trypsin,respectively,and the NPs could change the tertiary and secondary structure of pepsin and trypsin.Agglomeration of digestive protease was found and led to decrease of the activity of digestive protease in a concentration-dependent manner.（3）In vitro and in vivo experiments showed that the NPs in roasted mackerel could enter into mouse blood through intestinal tract.With the increase of roasting time,the amount of penetrated NPs decreased,but the damage of NPs on blood cells increased.The NPs was found that they can enrich in liver,heart,lung,brain,kidney and testis through blood transportation,respectively,with significant accumulation within liver,lung and brain.Residue of the NPs was found in liver and kidney after intragastric administration for 24 h.A temperature-dependent and concentration-dependent effect of the NPs was observed in NRK cytotoxicity.No inhibition of cell viability was found for the NPs roasted for 20-30 min,while 10%inhibition at 1 mg?mL-1 and more than 60%inhibition at 12 mg?mL-1 was found for the NPs roasted for 40 min.In summary,NPs cloud enter the mouse body and distributed in major organisms with a temperature dependent cellular toxicity.Meanwhile,NPs roasted for 40 min could promote 4times apoptosis of NRK cells.In summary,for the first time,the fluorescent NPs were discovered in the roasted Spanish mackerel.Their physicochemical properties,in vitro digestion,bio-distribution in mouse,and cytotoxicity were systemically studied.The obtained results laid the foundation for further studing of the bio-effects of endogenous NPs. |
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