Department of Biological Sciences
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Item Green synthesis of copper oxide nanoparticles and its efficiency in degradation of rifampicin antibiotic.(Springer, 2023-08-28) Nzilu, Dennis Mwanza; Madivoli, Edwin Shigwenya; Makhanu, David Sujee; Wanakai, Sammy Indire; Kiprono, Gideon Kirui; Kareru, Patrick GachokiIn recent ages, green nanotechnology has gained attraction in the synthesis of metallic nanoparticles due to their cost-effectiveness, simple preparation steps, and environmentally-friendly. In the present study, copper oxide nanoparticles (CuO NPs) were prepared using Parthenium hysterophorus whole plant aqueous extract as a reducing, stabilizing, and capping agent. The CuO NPs were characterized via UV–Vis Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), powder X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS). The UV–Vis spectra of CuO NPs showed a surface plasmonic resonance band to occur at 340 nm. FTIR analysis revealed the presence of secondary metabolites on the surface of CuO NPs, with a characteristic Cu–O stretching band being identified at 522 cm−1. Scanning electron micrographs and transmission electron micrographs showed that CuO NPs were nearly spherical, with an average particle of 59.99 nm obtained from the SEM micrograph. The monoclinic crystalline structure of CuO NPs was confirmed using XRD, and crystallite size calculated using the Scherrer-Debye equation was found to be 31.58 nm. DLS showed the presence of nanoparticle agglomeration, which revealed uniformity of the CuO NPs. Furthermore, the degradation ability of biosynthesized nanoparticles was investigated against rifampicin antibiotic. The results showed that the optimum degradation efficiency of rifampicin at 98.43% was obtained at 65℃ temperature, 50 mg dosage of CuO NPs, 10 mg/L concentration of rifampicin solution, and rifampicin solution at pH 2 in 8 min. From this study, it can be concluded that CuO NPs synthesized from Parthenium hysterophorus aqueous extract are promising in the remediation of environmental pollution from antibiotics. In this light, the study reports that Parthenium hysterophorus-mediated green synthesis of CuO NPs can effectively address environmental pollution in cost-effective, eco-friendly, and sustainable ways.Item Catalytic degradation of methylene blue by iron nanoparticles synthesized using Galinsoga parvifora, Conyza bonariensis and Bidens pilosa leaf extracts(Springer Nature Switzerland, 2019-09) Makhanu, David Sujee; Kareru, Patrick Gachoki; Wanakai, Sammy Indire; Madivoli, Edwin Shigwenya; Maina, Ernest Gachui; Nyabola, Augustine OtienoGreen synthesized metallic nanoparticles are environmentally friendly, bio-compatible, and highly stable. The aim of this study was to synthesize iron nanoparticles (FeNPs) from FeCl3 solution using aqueous leaf extracts of Galinsoga parvifora (Gp), Conyza bonariensis (Cb) and Bidens pilosa (Bp) and use them in degradation of methylene blue dye. The iron nanoparticles were characterized using UV–Vis spectrophotometer, FT-IR spectrophotometer, X-ray Fluorescence (EDXRF), X-ray difractometer (XRD), and scanning electron microscope (SEM). Phytochemical screening for presence of secondary metabolites revealed presence of phenolics, phytosterols and favonoids. The total phenolic and favonoid content in Galinsoga parvifora, Conyza bonariensis and Bidens pilosa leaf extracts were 57.67±1.27, 117.13±0.03, 126.27±0.013 mg Gallic Equivalent/g of Dry Weight (mg GAE/g DW) and 39.00±0.56, 45.50±0.59, 33.13±0.81 mg Rutin Equivalent/g of Dry Weight (mg RE/g DW) respectively. The UV–Vis spectrum of FeCl3 had a shoulder at 320 nm, which disappeared upon addition of G. parvifora, C. bonariensis and B. pilosa extracts confrming formation of iron nanoparticles. Evaluation of iron content of the synthesized nanoparticles revealed that the iron content in G. parvifora, C. bonariensis and B. pilosa extracts was 51, 47 and 44% respectively. XRD data revealed presence of a large amorphous coating that masked iron peaks, though 2 theta values observed have been reported to be of iron oxides. Methylene blue degradation studies revealed that CbNPs, BpNPs and GpNPs synthesized were good biocatalysts as they degraded the dye by 86, 84.3 and 92% respectively. Therefore, green synthesized iron nanoparticles is cost efective and environmentally safe in providing insight in the environmental removal of dyes.Item Phytofabrication of Iron Nanoparticles and their Catalytic Activity(Springer Nature Switzerland AG 2019, 2019-06-20) Edwin, Shigwenya Madivoli; Kareru, Patrick Gachoki; Gachanja, Anthony Ngure; Mugo, Samuel Mutuura; Makhanu, David SujeeMetallic nanoparticles that have photocatalytic activity can be synthesized using aqueous plant extracts. The aim of this study was to synthesize iron nanoparticles using Lantana trifolia extracts and to evaluate their ability to degrade Congo red dye. The nanoparticles were characterized using UV–Vis spectrophotometer (UV–Vis), Fourier transform infrared spectrophotometer, wide angle X-ray diffractometer, dynamic light scattering, transmission electron microscopy (TEM), and thermal gravimetric analyzer to determine the functional groups, thermal properties, crystalline phases and diameter distribution of the particles. Cyclic voltammetry was used to evaluate the redox potential of the extracts while photocatalytic activity of the nanoparticles was evaluated using a UV–Vis spectrophotometer. Functional groups analysis revealed presence of secondary metabolites having OH and C=C groups while a redox potential of + 0.3 V was an indication that the extracts can reduce iron. The presence of sharp peaks at 2θ values of 19.87°, 20.22°, 22.88°, 28.81°, 32.73°, 35.32°, 38.45°, 40.23° and 41.08° correspond to cubic crystal system of iron nanoparticles while particle aggregation was observed on TEM micrographs which also indicated that they were less than 200 nm. In the presence of H2O2, the nanoparticles catalyzed degradation of Congo red dye in a first order reaction that was temperature dependent. In conclusion, secondary metabolites in L. trifolia can reduce metallic ion to iron nanoparticles which can degrade Congo red dye.