Synthesis and investigation on synergetic effect of activated carbon loaded silver nanoparticles with enhanced photocatalytic and antibacterial activities.

In this study, we synthesized silver nanoparticle-loaded cashew nut shell activated carbon (Ag/CNSAC). The synthesized samples were characterized by XRD, XPS, SEM with EDS, FT-IR, and BET analysis. The XRD, XPS, and EDS data provided convincing proof that Ag loaded on CNSAC is formed. The energy dispersive spectrum analysis and X-ray diffraction pattern both supported the face-centered cubic and amorphous structures of Ag/CNSAC. The SEM micrographs showed the inner surface development of Ag NPs and many tiny pores in CNSAC. The photodegradation of methylene blue (MB) dye by the Ag/CNSAC photocatalyst was investigated. This effective degradation of MB dye by Ag/CNSAC is attributed to the cooperative action of Ag as a photocatalyst and CNSAC as a catalytic support and adsorbent. In tests with gram-positive and negative bacteria including Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the as-synthesized Ag/CNSAC showed outstanding antibacterial efficiency. Additionally, this study demonstrates a workable procedure for creating an affordable and efficient Ag/CNSAC for the photocatalytic eradication of organic contaminants.

Electrospray ionization tandem mass spectrometric study of protonated and alkali- cationized α/ε-hybrid peptides: differentiation of a pair of dipeptide positional isomers.

A new class of Boc-N-protected hybrid peptides derived from L- Ala and ε6-Caa (L-Ala = L-Alanine, Caa = C-linked carboamino acid derived from D-xylose) have been studied by positive ion electrospray ionization (ESI) ion-trap tandem mass spectrometry (MS/MS). MSn spectra of protonated and alkali-cationized hybrid peptides produce characteristic fragmentation involving the peptide backbone, the tert-butyloxycarbonyl (Boc) group, and the side chain. The dipeptide positional isomers are differentiated by the collision-induced dissociation (CID) of the protonated and alkali-cationized peptides. The CID of [M + H]+ ion of Boc-NH-L-Ala-ε-Caa- OCH3 (1) shows a prominent [M + H - C4H8]+ ion, which is totally absent for its positional isomer Boc-NH-ε-Caa-L-Ala-OCH3 (6), which instead shows significant loss of t-butanol. The formation of the [M + Cat - C4H8]+ ion is totally absent and [M + Cat - Boc + H]+ is prominent in the CID of the [M + Cat]+ ion of Boc-NH-L-Ala-ε-Caa- OCH3 (1), whereas the former is highly abundant and the latter is of low abundance for its positional isomer Boc-NH-ε-Caa-L-Ala-OCH3 (6). It is observed that 'b' ions are abundant when oxazolone structures are formed through a five-membered cyclic transition state in tetra-, penta-, and hexapeptides and the cyclization process for larger 'b' ions led to an insignificant abundance. However, the significant 'b' ion is formed in ε,α-dipeptide, which may have a seven-membered substituted 2-oxoazepanium ion structure. The MSn spectra of [M + Cat - Boc + H]+ ions of these peptides are found to be significantly different to those of [M + H - Boc + H]+ ions. The CID spectra of [M + Cat - Boc + H]+ ions of peptide acids containing L-Ala at the C-terminus show an abundant N-terminal rearrangement ion, [bn + 17 + Cat]+, which is absent for the peptide acids containing ε-Caa at the C-terminus. Thus, the results of these hybrid peptides provide sequencing information, the structure of the cyclic intermediate involved in the formation of the rearrangement ion, and distinguish a pair of dipeptide positional isomers.

Liquid chromatography electrospray ionization tandem mass spectrometry study of nilutamide and its stress degradation products: in silico toxicity prediction of degradation products.

Nilutamide, a nonsteroidal anti-androgen drug, widely used in the treatment of prostate cancer, was subjected to hydrolytic, photolytic, thermal and oxidative stress conditions as per International Conference on Harmonization guidelines Q1A (R2). Nilutamide showed significant degradation under basic hydrolysis and photolytic stress conditions, while it was stable to neutral, acidic and thermal stress conditions. Five degradation products were formed and the chromatographic separation of nilutamide and its degradation products was achieved on a Waters C18 column (4.6 × 250 mm, 5 µm) using a mobile phase consisting of acetonitrile and 0.1% of formic acid in an isocratic elution method. All these degradation products were characterized by LC/MS/MS in negative ion mode, combined with accurate mass measurements. To assign likely structures for the observed degradation products, the fragmentation patterns of the deprotonated drug and its degradation products were compared. The in silico toxicity of the drug and its degradation products was also assessed using TOPKAT software. The carcinogenicity probability of the degradation products, DP-I-IV, was greater than that of nilutamide.