Plumeria alba flower extract-mediated synthesis of recyclable chitosan-coated cadmium nanoparticles for pest control and dye degradation

In the current scenario, many synthetic chemicals have used long-term to control pests and mosquitoes, leading to the resistance of strains and toxicity effect on human beings. To overcome the adverse problem in recent advances, the scientific community is looking into nanofabricated pesticides and mosquitoes. This study aims to synthesize the recyclable chitosan-coated cadmium nanoparticles (Ch-CdNps) using Plumeria alba flower extract, which was further applied for insecticidal and mosquitocidal activities. The synthesized Ch-CdNps were confirmed by UV spectroscopy and FTIR analysis. The XRD, TEM, and DLS results confirmed the crystallinity with a spherical shape at 80-100 nm. The insecticidal activity proves that Ch-CdNps inhibited Helicoverpa armigera and Spodoptera litura at 100 ppm. In mosquitocidal, LC50 values of larvicidal of 1st instar were 4.116, 4.33, and 4.564 µg/mL, and the remaining three stages of instars, pupicidal, adulticidal, longevity, fecundity, and ovicidal assays inhibit the Anopheles stephensi followed by Aedes aegypti and Culex quinquefasciatus. Further, the first-order kinetics of photocatalytic degradation of methylene blue and methyl orange was confirmed. Based on the obtained results, Ch-CdNps can inhibit the pest, mosquitoes, and photocatalytic degradation.

Phytosynthesis of silver nanoparticles from Jatropha integerrima Jacq. flower extract and their possible applications as antibacterial and antioxidant agent

Jatropha integerrima Jacq. flower extract was used for the synthesis of silver nanoparticles in the current study. Various spectroscopic analyses were used to characterize the synthesized nanoparticles (JIF-AgNPs). The antibacterial efficacy of JIF-AgNPs was studied by well diffusion and microdilution techniques. In addition, the impact of JIF-AgNPs on free radicals was evaluated. On the ultraviolet–visible spectrum, the nanoparticles exhibit the highest absorbance at 422 nm. Based on the Fourier transform infrared spectrum, phenols and amino acids were involved in capping the JIF-AgNPs. Crystalline sphere-shaped nanoparticles with an average size of 50.07 nm and zeta potential of −19.0 mV were confirmed by X-ray diffraction, transmission electron microscopy, and dynamic light scattering analysis respectively. The JIF-AgNPs exhibit the highest and lowest growth inhibitory activity towards E. coli and B. subtilis. The minimal inhibitory concentration of JIF-AgNPs against E. coli, K. pneumoniae, S. aureus, and B. subtilis were 2.5, 5.0, 5.0, and 7.5 μg/mL, respectively. The JIF-AgNPs exhibited significant radical scavenging activities against DPPH (IC₅₀-32.5 ± 0.06 µg/mL), hydroxyl (IC₅₀-25 ± 0.09 µg/mL), Superoxide (IC₅₀-42.5 ± 0.13 µg/mL), and ABTs (IC₅₀-33.5 ± 0.15 µg/mL). Thus, synthesized nanoparticles were a good alternative to develop an antibacterial and antioxidant agent.

Isolation of bioactive compounds from lichen Parmelia sulcata and evaluation of antimicrobial property

BACKGROUND

Lichens were used as an ailment in the traditional medicine for treating various disorders for centuries. Since there is less evidence in the literature about the medicinal property of Parmelia sulcata (P. sulcata), we made a pioneer attempt to explore the antioxidant and antimicrobial properties of lichens.

METHODS

In the present study, the three Samples were collected by using the column chromatography by elucidating the ethyl acetate extract of P. sulcata, and the samples were subjected to DPPH and ABTS assays to find the free radical scavenging activity, total phenols and flavonoids were estimated. The minimum inhibitory concentration was evaluated against the bacterial species (Bacillus subtilis, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) and fungal species (Candida albicans and Aspergillus fumigatus) by the microdilution method. The best activity sample was analyzed using the Gas Chromatography-Mass Spectrometry (GC-MS), Fourier Transmission Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance (NMR).

RESULTS

The results shown that all the samples contain phenols and flavonoids which are responsible for antioxidants, antibacterial and antifungal activities. Among that sample-3 shown best antimicrobial activity and it was analyzed and identified as 7-hydroxy-3-(2-methylbut-3-en2-yl)-chromen-2-one.

CONCLUSION

The outcome of the study suggests that sample-3 shown good antimicrobial activity and identified as 7-hydroxy-3-(2-methylbut-3-en2-yl)-chromen-2-one. It can be a resource for further studies.

Biosynthesis, characterization, and antibacterial activity of gold nanoparticles

BACKGROUND

In recent decades focus of research has been toward an alternative antibacterial agent because of growing bacterial resistance and side effects of antibacterial agents. In the current study, the antibacterial activity of gold nanoparticles has been evaluated on selected human pathogens.

METHODS

In this study, we used panchagavya (PG) to synthesize gold nanoparticles, and the resulting nanoparticles (PG-AuNPs) were characterized by several spectroscopic techniques. In addition, antibacterial activity of PG-AuNPs against Escherichia coli, Bacillus subtilis, and Klebsiella pneumoniae were studied by well diffusion method.

RESULTS

The synthesis of AuNPs was affirmed by a colour change, which was further validated by UV-vis spectra with a maximum absorption peak at 527 nm. Bandgap energy was calculated as 2.13 eV by Tauc method from the UV result. The presence of amino acids and proteins in PG was responsible for the conversion of gold ions to AuNPs, according to FTIR analysis. (111), (200), (220), and (311) crystallographic planes were observed by XRD; further crystalline nature was validated by SAED analysis. The size and zeta value were found to be 53.29 nm and -9.8 mV respectively. Spherical shaped nanoparticles and elemental structure of PG-AuNPs were confirmed by HRTEM and EDS analysis. The antibacterial activity of PG-AuNPs showed the maximum and minimum zone of inhibition against K. pneumoniae (17.12 ± 0.14 mm) and B. subtilis (11.42 ± 0.58 mm).

CONCLUSION

Antibacterial activity of PG-AuNPs was found to be strong against gram negative bacteria and moderate against gram positive bacteria. Based on the result, it was concluded that PG-AuNPs could be used to combat antibiotic drug resistance. Besides, in vitro and in vivo toxicity studies of PG-AuNPs should be conducted.