Study on the concentration of gold nanoparticles for antibacterial activity

Abstract

Pure and polymer coated (PVP and PVA) gold nanoparticles (AuNPs) with 0.001 and 0.002 M concentrations were synthesised by chemical method. Transmission electron microscopy (TEM) images showed that the size of nanoparticles is below 50 nm whereas the selected area electron diffraction (SAED) pattern indicated cubic structure with lattice parameter of 4.09 Å for each sample. The absorption bands for all these samples lie between 500 and 550 nm as observed from UV–vis spectra. The photoluminescence (PL) spectra taken at 300 nm excitation wavelength showed emission between 415 and 430 nm whereas the particle size determined from particle size analyser lies below 100 nm for all samples. The ultrasonic velocity measured as a function of temperature showed the decrement above 50 °C for PVP and PVA coated AuNPs. The antimicrobial activity for these above taken concentrations of gold samples showed negative effect, whereas higher concentration of AuNPs of 0.005 M showed the positive effect for gram-positive and gram-negative bacteria.

Chemical and green synthesis of gold nanoparticles for mRNA delivery in vitro

“…The citrate-synthesised AuNPs were much smaller than those of the curcumin-synthesised AuNPs using NTA, but TEM showed similar size distributions for both types of AuNPs. Similar small TEM sizes were previously noted for citratesynthesised AuNPs [24,33] and gallic acid-synthesised AuNPs [34]. However, much larger TEM sizes were reported for other green synthesised AuNPs [24].…”

“…Similar small TEM sizes were previously noted for citratesynthesised AuNPs [24,33] and gallic acid-synthesised AuNPs [34]. However, much larger TEM sizes were reported for other green synthesised AuNPs [24]. NTA confirmed the presence of nanometer-sized particles and nanocomplexes (<140 nm), ideal for gene therapy with zeta potentials (>20 mV), inferring good colloidal stability for in vivo applications [35].…”

“…The absorption of light by free electrons or surface plasmons of the NP's surface causes them to oscillate, which is seen as an absorption band on the UV-vis spectra, with any changes in the SPR indicating a change in size or shape due to functionalisation [22]. The UV absorption spectra of the AuNPs (figure 1) had peaks at a λ max around 520 nm (AuNP ct ) and 525 nm (AuNP cc ), indicating successful synthesis with no byproducts, correlating to that in literature [3,9,23,24].…”

Structural, magnetic and antibacterial studies of gadolinium doped cobalt ferrite nanoparticles synthesized at low temperature

“…Cobalt ferrite possesses reasonably high electrical resistivity, coercivity, moderate saturation magnetisation, large magnetostriction (λ s ∼ 110 × 10 −6 ) and a stable ferromagnetic phase even at higher temperatures, making it suitable for sensor and actuator applications [1][2][3][4][5][6][7]. However, several intrinsic and extrinsic parameters such as cation distribution, crystallite size, chemical composition, uniform grain size, porosity, and method of preparation play key role in tailoring the electrical, magnetic, and optical properties of these cobalt ferrites.…”

Enhancement in dye removal by photocatalytic degradation using metal oxide nanoparticles embedded on activated carbon powder and study of their antibacterial activity

“…Furthermore, numerous peer-reviewed studies investigated the ability of activated carbon to adsorb bacteria and its usage as an antibacterial agent in biomedical research [15,16]. Recently, studies have focused on the production of reactive oxygen species (ROS) by metal nanoparticles impregnated activated carbon in order to achieve the maximum antibacterial effect [17][18][19]. Parvathi et al [20] suggest that the adsorption ability of activated carbon confines bacteria around the nanoparticle environment and the oxidative stress induced by metal ions can promote cell wall rupture.…”