Evaluation of the microbial growth response to inorganic nanoparticles

Abstract

In order to enhance the utilization of inorganic nanoparticles in biological systems, it is important to develop a fundamental understanding of the influence they have on cellular health and function. Experiments were conducted to test silica, silica/iron oxide, and gold nanoparticles for their effects on the growth and activity of Escherichia coli (E. coli). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to characterize the morphology and quantify size distribution of the nanoparticles, respectively. TEM was also used to verify the interactions between composite iron oxide nanoparticles and E. coli. The results from DLS indicated that the inorganic nanoparticles formed small aggregates in the growth media. Growth studies measured the influence of the nanoparticles on cell proliferation at various concentrations, showing that the growth of E. coli in media containing the nanoparticles indicated no overt signs of toxicity.

Silver and gold nanoparticles synthesized from Streptomyces sp. isolated from acid forest soil with special reference to its antibacterial activity against pathogens

“…Biocompatible AuNPs were found to be efficient agent in cancer therapy [28]. Williams et al [29] reported that AuNPs used alone did not show antibacterial activity. However, AuNPs conjugated with antibiotics were found to improve antibiotic activity and delivery.…”

Evaluation of the Biological Effects of Externally Tunable, Hydrogel Encapsulated Quantum Dot Nanospheres in Escherichia coli

“…During this run, the nanospheres remained stable and showed little change in hydrodynamic radius. Stability of PEG coated gold particles in LB media has previously been observed as well [24]. …”

“…These experimentally obtained results indicate that PNIPAM coated CdTe QDs are a promising alternate to uncoated QDs. Coupled with the externally tunable dot distribution capabilities derived from the PNIPAM networks [22,24], this novel nanoplatform may be useful for combinatorial therapeutics. We are currently assessing optically modulated responses of several neuronal models to the bio-conjugated nanospheres.…”

“…These cultures were incubated at 37 °C, shaking at 100 rpm and the optical density (OD) was measured using A 600nm at selected times to determine growth rates. 600 nm is selected, because to measure bacterial growth by light scattering it is best to pick a wavelength where absorption is at a minimum and for most bacterial cultures wavelengths around 600 nm are a good choice [24]. This procedure was followed for all concentrations of QD/PNIPAM gels evaluated.…”

“…Therefore, the inherent temperature-sensitive volumetric transition properties of PNIPAM offer the potential to control QD proximity within the nanospheres for in vitro or in vivo applications. As the CdTe QD toxicity has the ability to effectively kill E. coli bacteria by impairing the cell's anti-oxidative system, this serves as a cellular model to assess the toxicity profile of the hydrogel encapsulated QD nanospheres [24,25]. The existing reports have assessed single QD core-shell polymeric structure's toxicity where traditional polymer encapsulation is not externally tunable, and cannot control the intermediate distance between the adjacent dots and is not suitable for drug delivery applications in which triggered release is necessary.…”