GREEN SYNTHESIS, CHARACTERISATION AND ANTIBACTERIAL ACTIVITY EVALUATION OF SILVER SULFIDE NANOPARTICLES OF SENNA OCCIDENTALIS (L.)

The study focuses on the green synthesis of silver sulfide nanoparticles using aqueous Senna occidentalis (L.) extract as reducing, capping, and stabilizing agents. Fourier Transform Infra-red Spectroscopy (FTIR) and Scanning electron microscopy (SEM) characterized the synthesized silver sulfide nanoparticles. FT-IR spectrum of Senna occidentalis leaves aqueous extract as shown in Fig. 3 below shows a number of peaks, thus reflecting its complex nature. The bands at 3175cm^-1 is characteristic of the alcohol/phenol –OH stretching vibration, 2361.44cm^-1 an attribute O=C= Stretching representing carbon dioxide. The weak peak at 1594cm^-1 is assigned for C=O bending, indicating carboxylic acid, and the band at 995cm-1 represents the C=C bending signifying alkene. Fig. 4 below shows the FTIR result of the synthesized silver sulfide nanoparticle at different bands. The bands at 3785 and 3703 cm^-1 correspond to O-H stretching vibration, indicating the presence of alcohol/phenol; the peak at 3406 cm^-1 reflects N-H stretching of alphatic primary amine. Bands at 2919 and 2855.82cm^-1 correspond to the C-H stretching of aromatic compounds. The band at 1713.88cm-1 indicates C=N stretching attributed to amine, the band at 1601cm^-1 is assigned to C=C, a characteristic of conjugated alkene. The shape of the silver sulfide nanoparticles is spherical with few exceptional as ellipsoidal. Senna occidentalis Ag₂S nanoparticles were observed to possess antimicrobial activity as it inhibited some of the tested microorganisms (bacteria and fungi), giving clear inhibition zones that were the same or higher in some cases to those of the standard antibiotic or antifungal used. The nanoparticles antifungal inhibition activity was seen to be better than griseofulvin (the standard antifungal used) in the case of Aspergillus fumigatis.