We show that sodium 9,10-epoxy-12-hydroxytetradecanoate (SEAR), an epoxidized derivative of ricinoleic acid, simultaneously functioned as reducing and stabilizing agents in the synthesis of silver nanoparticles in alkaline aqueous medium. The advantage of using SEAR is its biodegradability and nontoxicity, which are important characteristics for mitigation of environmental impact upon discharge of nanoparticles into terrestrial and aquatic ecosystems. The SEAR concentration was found to impact considerably the size distribution of silver nanoparticles (AgNPs). A concentration below the SEAR critical micelle concentration (CMC) generated 23 nm sized AgNPs with 10 nm standard deviation, while 50 nm sized AgNPs ( = 21 nm) were obtained at a concentration above the SEAR CMC. FTIR analysis revealed that the carboxylate that constitutes the SEAR hydrophilic head binds directly to the AgNPs surface promoting stabilization in solution. Finally, AgNPs turned into Ag 2 S upon contact with wastewater samples from Wastewater Treatment Plant at Federal University of Rio Grande do Norte (UFRN), Brazil, which is an interesting result, since Ag 2 S is more environmentally friendly than pure AgNPs.

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For many cancers, early detection is the key to improve survival and reduce the morbidity, which is associated with radical resections due to late diagnosis. Here, we describe the efficiency of primary antibody-conjugated gold nanoparticles (AuNPs) to specifically target chronic inflammatory processes, specially M2 macrophages, in tissue sections of ulcerative colitis (UC) and steatohepatitis in rats which may lead to colorectal cancer and liver carcinoma, respectively. In this study, we demonstrate that AuNPs synthesized by a simple, inexpensive, and environmentally compatible method can be easily conjugated with the antibodies anti-COX-2, anti-MIF, and Alexa Fluor® 488 (ALEXA) to perform immunofluorescence staining in inflamed tissues. Moreover, we showed that primary antibody-conjugated gold nanoparticles (AuNPs) can be used to target M2 macrophages by flow cytometry. We designed three immunofluorescence staining protocols of tissue section with AuNPs for 30 min and overnight incubation, as well as one flow cytometry protocol of M2 macrophage labeling with AuNPs for 30 min. Immunofluorescence and flow cytometry results suggest that conjugation was achieved by direct adsorption of antibodies on the AuNPs surface. When compared to the standard ALEXA protocol in immunofluorescence (IF) and flow cytometry (FC), our 30-min incubation protocol using AuNPs instead of ALEXA decreased from approximately 23 h to 5 h for IF and from 4 h to 1 h for FC, proving to be less laborious, which makes the method eligible for inflammation-induced cancer diagnostic.