The morphological changes in the internal organs of laboratory animals after prolonged oral administration of gold nanoparticles

Recently gold nanoparticles(GNPs)have been actively studied as photot hermal converters,drug carriers,and imaging agents in a wide range of applications in cancer diagnosis and ther apy.The prolonged peroral administration of GNPs in a range of sizes was performed to investigate the morphological changes and their reversibility in the internal organs of laboratory animals.In this study,GNP's with average diameters of 2 nm,15 nm and 50nm were administered during 30 days,and the reversibility of morphological changes was investigated 14 days after administration.After the prolonged administration of GNPs,the severity of morphological changes in the liver,kidney,spleen and lymph nodes depended on the nanoparticle size.Specifically,50 nm nano-particles caused the most pronounced dystrophic and necrobiotic effects,whereas the smallest 2 nm nanoparticles caused proliferative changes.Most importantly,the development of patho-logical processes was reversible,as evidenced by the gradual restoration of the organ structure at 14 days after the end of GNPs administration.

Optical clearing mechanisms characterization in muscle

Optical immersion clearing is a technique that has been widely studied for more than two decades and that is used to originate a temporary transparency effect in biological tissues.If applied in cooperation with clinical methods it provides optimization of diagnosis and treatment procedures.This technique turns biological tissues more transparent through two main mechanisms-tissue dehydration and refractive index(RI)matching between tissue compo-nents.Such matching is obtained by partial replacement of interstit ial water by a biocompat ible agent that presents higher RI and it can be completely rever sible by natural rehydration in vrivo or by assisted rehydration in ex vivo tissues.Experimental data to characterize and discriminate between the two mechanisms and to find new ones are necessary.Using a simple method,based on collimated transmittance and thickness measurements made from muscle samples under treatment,we have estimated the diffusion properties of glucose,ethylene glycol(EG)and water that were used to perform such char acterization and discrimination.Comparing these properties with data from literature that characterize their diffusion in water we have observed that musde cell membrane permeability limits agent and water diffusion in the muscle.The same experi-mental data has allowed to calculate the optical dearing(OC)eficiency and make an inter-pretation of the internal changes that occurred in muscle during the treatments.The same methodology can now be used to perform similar studies with other agents and in other tissues in order to solve engineering problems at design of inexpensive and robust technologies for a consider.able improvement of optical tomogr aphic techmiques with better contrast and in depth imaging.