Immobilized papain on gold nanorods as heterogeneous biocatalysts.

Papain, a thiol protease present in the latex of Carica papaya, is an enzyme which exhibits broad proteolytic activity, and, for this reason, it is utilized in a variety of industrial applications. Immobilization of papain on gold nanoparticles highly preserves its activity and enhances the stability, allowing the reuse of the linked enzyme many times without any significant loss of its catalytic performance. In particular, kcat and KM values remain substantially unchanged, while immobilized form shows a higher activity on a wider pH range retains 80 % residual activity also at 90 °C and shows higher functionality than the free form when incubated for long time (1 h) at 90 °C and at extreme pH values (3 and 12). A higher activity of immobilized papain with respect to the free form in the presence of various bivalent metal ions, known as strong inhibitors of papain, was also found. The reasons of this enhanced stability of gold nanorods immobilized papain are discussed.

Scolicidal Effects of Chitosan-Curcumin Nanoparticles on the Hydatid Cyst Protoscolices.

PURPOSE: In the current era, cystic echinococcosis (CE), as larval stage of Echinococcus granulosus, is considered as a threat to human health. Scolicidal agents used in the surgery of cysts have different side effects. Therefore, the present study aimed to assess the effects of chitosan nanoparticles containing curcumin (Ch-Cu NPs) on the protoscolices of the hydatid cyst in vitro. METHODS: Ch-Cu NPs were synthesized using a simple co-precipitation method and their structural and morphological properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta analyzer, and Fourier transform infrared (FT-IR) spectroscopy. Then, the effects of different concentrations of Ch-Cu NPs (0.25, 0.05, 1, 2, and 4 mg/mL) on the fatality rate, and the length and width of protoscolices in different times (5, 10, 20, 30, and 60 min) were investigated. In addition, the SEM technique was used to evaluate the structure of the protoscolices after treatment. RESULTS: Based on the results, the presence of curcumin on the chitosan nanoparticles was confirmed by FT-IR analysis. Further, XRD analysis approved the crystal structure of chitosan NPs. Furthermore, the highest fatality rate was 68% in 4 mg/mL concentration of Ch-Cu NPs. The length and width of protoscolices decreased based on the high concentrations of Ch-Cu NPs, compared to the control group. CONCLUSION: Finally, Ch-Cu NPs expressed good scolicidal activities, which made them suitable to be considered as an anti-protoscolex agent.