Synthesis and Characterization of a pH- and Temperature-Sensitive Fe3O4-SiO2-Poly(NVCL-co-MAA) Nanocomposite for Controlled Delivery of Doxorubicin Anticancer Drug.

This work reports the synthesis, characterization, and in vitro release studies of pH- and temperature-sensitive Fe3O4-SiO2-poly(NVCL-co-MAA) nanocomposite. Fe3O4 nanoparticles were prepared by chemical coprecipitation, coated with SiO2 by the Stöber method, and functionalized with vinyl groups. The copolymer poly(N-vinylcaprolactam-co-methacrylic acid) (poly(NVCL-co-MAA)) was grafted onto the functionalized Fe3O4-SiO2 nanoparticles by free radical polymerization. XRD, FTIR, TGA, VSM, and TEM techniques were performed to characterize the nanocomposite. The release behavior of Doxorubicin (DOX) loaded in the nanocomposite at pH 5.8 and 7.4, and two temperatures, 25 and 37 °C, was studied. According to the release studies, approximately 55% of DOX is released in 72 h at pH 7.4, regardless of temperature. At pH 5.8, 78% of DOX was released in 48 h at 25 °C, and when increasing the temperature to 37 °C, more than 95 % of DOX was released in 24 h. The DOX release data treated with Zero-order, first-order, Higuchi, and Korsmeyer-Peppas models showed that Higuchi's model best fits the data, indicating that the DOX is released by diffusion. The findings suggest that the synthesized nanocomposite may be useful as a DOX carrier in biomedical applications.

Environmental friendly cold-mechanical/sonic enzymatic assisted extraction of genipin from genipap (Genipa americana).

An efficient cold-mechanical/sonic-assisted extraction technique was developed for extraction of genipin from genipap (Genipa americana) peel. Ultrasound assisted extraction (285 W, 24 kHz) was performed at 5, 10 and 15 °C for 5, 10 and 15 min. After cold-extraction, genipin was separated from pectin and proteins by aid of fungal pectinesterase. The maximum yield of non-cross-linked genipin was 7.85±0.33 mg/g, at 10 °C for 15 min by means of ultrasound extraction. The protein amount in extracts decreased in all samples. If mechanical process is combined with ultrasound assisted extraction the yield is increased by 8 times after the pectinesterase-assisted polyelectrolyte complex formation between pectic polysaccharides and proteins, avoiding the typical cross-linking of genipin. This novel process is viable to obtain non-cross-linked genipin, to be used as a natural colorant and cross-linker in the food and biotechnological industries.