RESUMO
Gold nanoparticles [GNPs] are currently used in several consumer products as well as in laboratory-based research either as a diagnostic imaging agent or as a therapeutic agent in gene delivery and photothermal cancer therapy. They are synthesized by chemical methods in which toxic reducing agents are involved. There is a growing need to develop environmentally benign NP synthesis processes that are free from toxic chemicals. The study aimed to ascertain the possible histological alterations that might occur in the pulmonary alveoli of adult albino rats after intraperitoneal administration of 10 nm GNPs prepared by two different methods [chemically prepared and green synthesized]. Fifty adult male albino rats [140-160 g] were assigned to three groups. Group I was the control group. The rats in this group were further divided into three equal subgroups Ia, Ib, and Ic that received daily intraperitoneal injection of PBS, trisodium citrate, and cumin-gum Arabic solutions, respectively. Rats in group II received a daily intraperitoneal injection of 100 micro l of chemically prepared GNPs using trisodium citrate. Rats in group III received a daily intraperitoneal injection of 100 micro l of green-synthesized GNPs using cumin and gum Arabic. After 7 days, the animals were euthanized and specimens from the lungs were taken and processed for histological and immunohistochemical studies. H and E-stained sections of group II rats depicted multifocal thickening of the interalveolar septa and collapsed alveoli. Immunohistochemical analysis revealed high vimentin expression. Ultrastructurally, type II pneumocytes showed degenerative changes. Relatively thick interalveolar septa with many active interstitial cells were also seen. GNPs were detected in pneumocytes and alveolar macrophages. In contrast, the lung sections of group III rats showed considerable preservation of normal alveolar architecture with nearly normal vimentin immunoreactivity. GNPs were detected in the pneumocytes and interalveolar septa as well. Green-synthesized GNPs using cumin-gum Arabic are safer for the pulmonary alveoli compared with chemically prepared GNPs using trisodium citrate. Long-term studies are required to verify the toxicity of GNPs on various cell types