Optical and Structural Properties of Cobalt Nanoparticles Synthesized by Laser Ablation

Abstract

Pulsed laser ablation in liquid (PLAL) technique can produce high purity nanoparticles, it is a top-down physical method based on the principle of dividing metal ion bulk precursors into metal atoms, this method was used in this work to synthesis cobalt nanoparticals (CoPNs) with the use of Nd: YAG laser with two wavelengths (355 nm) and (532 nm) at energies (500 mJ) and (600 mJ) respectively, with number of pulses (1000,1100, 1200, 1300, and 1400) for each wavelength. The properties of the prepared nanoparticles were studied by UV-Vis, XRD, SEM with EDX, AFM, and FTIR analysis and then its antibacterial activity was studied by applying it on two types of bacteria with gram-positive (Staphylococcus aureus, Streptococcus mutans) and two gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) isolated from the oral cavity. The findings showed that CoNPs prepared using the PLAL approach have antibacterial activity and could be employed to kill hazardous and pathogenic bacteria.

Antibacterial activity of silver nanoparticles created by one step nanosecond Nd: YAG laser ablation in water

“…In general, NPs' antibacterial activity is primarily dependent on electrostatic attraction between positively charged NPs and negatively charged bacterial cell surfaces, and this attraction is critical for NPs' bactericidal activity [40]. Because of the cellular toxicity of NPs, cell death is caused by mitochondrial damage and the upregulation of several apoptotic proteins [5]. Table 3 compares our findings to those of other studies by displaying the synthesis techniques of silver nanoparticles and their antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria strains.…”

“…The peak at 1635 cm −1 is attributed to Ag-O stretching vibration (Hydroxyl group). Furthermore, in all FTIR spectra, the band below 600 cm −1 is in charge of the formation of Ag NPs and their oxides[5]. It can be seen from the figure that the intensity of the FTIR spectrum varied with the change in the laser fluence, whereas the width of the observed peaks remained relatively constant due to increased scattering of laser light and increased absorption of colloidal solution, resulting in a decrease in the transmission spectrum.The crystalline phase of Ag nanoparticles prepared with different fluences (2.04, 6.12, 10.2 J cm −2 ) for 100 pulses was confirmed by XRD investigation as shown in figure3.…”

“…Therefore, creating nanoparticles with the proper size distribution, morphology, and crystallinity is critical [3]. To date, several controlled synthesis methods for Ag NPs have been reported such as evaporation condensation, chemical reduction, sol-gel, laser ablation, electron irradiation, microwave processing, electro-chemical, photochemical, and biosynthesis [4,5]. Each method has advantages and disadvantages [6][7][8][9][10].…”

“…Antibacterial activity experiments on various microorganisms clearly demonstrated the effectiveness of nanoparticles against bacterial growth due to the smaller particle size that penetrates the bacterial membrane. Rashid et al (2022) [5] synthesised silver nanoparticles (Ag NPs) by utilising a Nd:YAG laser with two wavelengths 355 nm and 532 nm at energies of 500 mJ and 600 mJ, respectively, with the number of pulses (500, 600, 700, 800, and 900), then tested for antibacterial activity against two Grampositive bacteria (Staphylococcus aureus, Streptococcus mutans) and two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) isolated from the oral cavity. The results showed that the manufactured samples at the wavelength of 355 nm are the most effective under the conditions of this investigation.…”