Association of Quantum Dot Nanoparticles with Pseudomonas aeruginosa Biofilm

Abstract

Quantum dots (QDs) of two different surface chemistries (carboxyl [COOH] and polyethylene glycol [PEG] modified) were utilized to determine the impact of surface functionality on QD mobility and distribution in Pseudomonas aeruginosa PAO1 biofilms. Confocal laser scanning microscopy was utilized to evaluate QD association with biofilm components (proteins, cells, and polysaccharides). Quantum dots did not preferentially associate with cell surfaces compared but did colocalize with extracellular proteins in the biofilm matrix. Neither PEG nor COOH QDs were found to be internalized by individual bacterial cells. Neither QD functionality nor flow rate of QD application (0.3 mL min(-1) or 3.0 mL min(-1)) resulted in a marked difference in QD association with P. aeruginosa biofilms. However, center of density determinations indicated COOH QDs could more easily penetrate the biofilm matrix by diffusion than PEG QDs. Biofilms with PEG QDs associated had rougher polysaccharide layers and rougher cell distribution than biofilms with COOH QDs. This work suggests natural biofilms may serve as deposition locations in natural and engineered environmental systems, and biofilm structural parameters may change based on exposure to nanomaterials of varied physical characteristics.

When nanoparticles meet biofilms—interactions guiding the environmental fate and accumulation of nanoparticles

“…The organic corona as well as other organic coatings of NPs are likely to have significant impacts on NP–biofilm interactions. For example, cadmium selenide quantum dots (QDs) conjugated with polyethylene glycol were found to penetrate more easily into Pseudomonas aeruginosa PAO1 biofilms than QDs having surface carboxyl (–COOH) groups (Morrow et al, 2010). In another study, incubation of Pseudomonas fluorescens biofilms with silver NPs pre-exposed to NOM was shown to result in greater cell viability compared to silver NPs without NOM exposure (Wirth et al, 2012), suggesting that the NOM-based corona associated with the NPs had a mitigating effect on silver toxicity.…”

“…All three are likely to occur in the complex and dynamic environments where biofilms naturally occur. Most recent studies on NP–biofilm interactions have examined either the combined effects of initial surface NP deposition and penetration into the biofilm (Morrow et al, 2010; Habimana et al, 2011; Peulen and Wilkinson, 2011) or all three steps of NP–biofilm interactions outlined above in Section “Nanoparticle–Biofilm Interactions” (transport, attachment, migration; Fabrega et al, 2009; Choi et al, 2010). Overall, the migration of NPs into the 3D matrix of the biofilm is the least understood step of NP–biofilm interactions.…”

Quantum Dots-Based Nano-Coatings for Inhibition of Microbial Biofilms: A Mini Review

“…Biofilms treated with PEGlyated QDs had rough polysaccharide layers and cell distribution compared to -COOH functionalized QDs. It was thus concluded that treatment with nanomaterials can result in varying the structural parameters of biofilm [47]. The fluorescent property of QDs would thus allow recognition of biofilm formation at different growth stages and environmental conditions.…”

Environmental Occurrences, Behavior, Fate, and Ecological Effects of Nanomaterials: An Introduction to the Special Series

“…One review paper provides an ecological perspective on the role natural nanomaterials play in biological processes and outlines important issues that need to be addressed in future research to determine the ecological responses to ENMs (Bernhardt et al, 2010). Four research papers focus on ENM sources, fate, and bioavailability including the magnitude of Ag NP releases from consumer products (Benn et al, 2010), transport and distribution of fullerene materials in soils (Wang et al, 2010), quantum dot partitioning to biofilms including novel methods to pinpoint their location (Morrow et al, 2010), and Cu NP bioavailability to the earthworm Eisenia fetida and the significance of this entry point for NPs into the food web (Unrine et al, 2010). This collection of papers also highlights several data gaps that must be filled to allow risk assessment using existing tools.…”