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Green synthesis of silver nanoparticles (AgNPs) has been extensively studied by using a variety of plant extracts for applications in biomedical sciences and engineering. However, there are no reports on the synthesis of AgNPs by utilizing the berry extract of Sea Buckthorn, which is a traditional Chinese medicine and exhibits a wide spectrum of antioxidant, anti-inflammatory and anticancer activities. In this paper, we report an easy and eco-friendly technique for the preparation of AgNPs using the Sea Buckthorn berry extract under ultrasonic radiation at ambient temperature and the evaluation of both biosynthesis parameters and biological activities. The UV-visible spectrum and dynamic light scattering (DLS) analysis showed that the size of AgNPs was sensitive to the biosynthesis parameters, such as the pH of the extract, material proportion and reaction time, offering a size-controlled synthetic method for AgNPs. The X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and DLS studies showed that the AgNPs (pH 10.0; material proportion 1 : 1; 4 h) had a face-centered cubic (fcc) structure and spherical shape with an average particle size of 27.3 ± 0.2 nm covered by anions, and existed in a monodispersed form with a polydispersity index (PDI) of 0.213. The biosynthesized AgNPs showed potent anticancer activity against human colorectal cancer (HCT116 and SW620), hepatoma cancer (HepG2), breast cancer (MCF-7) and cervical cancer (HeLa) cell lines as well as strong antioxidant activity. The IC50 values for these five cell lines were 8.77, 4.61, 14.59, 16.05 and 27.98 μg mL−1, respectively. However, the biosynthesized AgNPs revealed poor inhibition activities for the growth of E. coli and S. aureus. These results confirmed that the Sea Buckthorn could be a low-cost, nontoxic and eco-friendly natural resource for the synthesis of AgNPs, which might be useful for the development of new alternative antioxidant and anticancer agents in biomedicine. [ABSTRACT FROM AUTHOR]

A series of zeolite catalysts, M(Cu, Fe, Co)-ZSM-5, was prepared by an impregnation method and evaluated for the selective catalytic combustion of acrylonitrile (AN-SCC). Cu-ZSM-5, exhibiting the highest AN conversion activity and best N2 yield, was further selected for an AN-SCC mechanism investigation, wherein both experimental [in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)] and theoretical [density functional theory (DFT)] approaches were employed. The in situ DRIFTS revealed that AN-SCC followed a hydrolysis mechanism at T ＜ 300 °C via intermediates of acylamino species (–CONH2) and NH3, while it followed an oxidation mechanism at T ＞ 300 °C via an intermediate of NCO. The DFT simulations gave much deeper insights suggesting that: (i) the NCO could be generated by oxidation of AN over [Cu]+ active sites, with an assistance of dissociated atomic O from gaseous O2; (ii) three types of reaction routes could be proposed for the further reaction of NCO to produce N2, namely NCO direct dissociation, NCO coupling, and NO + NCO reaction; and (iii) the last route (NO + NCO), possessing the lowest energy barrier, was the most probable reaction pathway, wherein the NO could be produced by oxidation of NCO. The DFT energy calculation results and microkinetic analyses revealed that the NCO generation step, possessing an energy barrier of 17.0 kcal mol−1 and a forward reaction rate constant of 2.20 × 107 s−1, was the rate-determining step of the whole catalytic cycle. [ABSTRACT FROM AUTHOR]

A series of zeolite catalysts, M(Cu, Fe, Co)-ZSM-5, was prepared by an impregnation method and evaluated for the selective catalytic combustion of acrylonitrile (AN-SCC). Cu-ZSM-5, exhibiting the highest AN conversion activity and best N 2 yield, was further selected for an AN-SCC mechanism investigation, wherein both experimental [in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)] and theoretical [density functional theory (DFT)] approaches were employed. The in situ DRIFTS revealed that AN-SCC followed a hydrolysis mechanism at T < 300 °C via intermediates of acylamino species (-CONH 2 ) and NH 3 , while it followed an oxidation mechanism at T > 300 °C via an intermediate of NCO. The DFT simulations gave much deeper insights suggesting that: (i) the NCO could be generated by oxidation of AN over [Cu] + active sites, with an assistance of dissociated atomic O from gaseous O 2 ; (ii) three types of reaction routes could be proposed for the further reaction of NCO to produce N 2 , namely NCO direct dissociation, NCO coupling, and NO + NCO reaction; and (iii) the last route (NO + NCO), possessing the lowest energy barrier, was the most probable reaction pathway, wherein the NO could be produced by oxidation of NCO. The DFT energy calculation results and microkinetic analyses revealed that the NCO generation step, possessing an energy barrier of 17.0 kcal mol -1 and a forward reaction rate constant of 2.20 × 10 7 s -1 , was the rate-determining step of the whole catalytic cycle.