Microbial Growth Response to Hydrogel Encapsulated Quantum Dot Nanospheres
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1064-PP06-17
Microbial Growth Response to Hydrogel Encapsulated Quantum Dot Nanospheres Somesree GhoshMitra1, Tong Cai2, Santaneel Ghosh3, Arup Neogi2, Zhibing Hu2, and Nathaniel Mills1 1 Texas Woman's University, Denton, TX, 76201 2 University of North Texas, Denton, TX, 76203 3 Southeast Missouri State University, Cape Girardeau, MO, 63701
ABSTRACT Hydrogel based Quantum dots (QD) has become an interesting subject of study for labeling and drug delivery in biomedical research due to their unique responses to the external stimuli. In this paper, biological effect of a novel hydrogel based QD nanomaterial system on Escherichia coli (E. coli) bacteria is presented. The experimental evidence shows that appropriately coated CdTe QDs has reduced or negligible toxicity to this model cell system, even when exposed to higher dosages. Thus, coated QDs that possess tunable packing density have the potential to control system efficiency and may be suitable for various biomedical applications.
INTRODUCTION Quantum dots (QDs) are now used extensively for labeling [1-2] in biomedical research due to their unique photoluminescence behavior; (1) size-tunable emission color, (2) a narrow and symmetric emission profile and (3) a broad excitation range. Uncoated QDs made of CdTe core are toxic to cells because of release of Cd2+ ions into the cellular environment. This problem can be partially solved by encapsulating QDs with hydrophilic polymers, like poly(Nisopropylacrylamide) (PNIPAM) or poly(ethylene glycol) (PEG). Based on biological compatibility, adaptability to pH and temperature as well as being responsive to magnetic field swelling properties, hydrogel nanospheres have become suitable carriers for drugs, fluorescence labels, magnetic particles for hyperthermia applications and particles that have strong optical absorption profiles for optical excitation. The toxicity of uncoated QDs are known [3-5]; however, only a very limited number of studies [6] have been specially designed to assess thoroughly the toxicity of nanosphere encapsulated QDs against QD density and dosing level. In this work, we present preliminary studies of biological effects of a novel QD based nanomaterial system on E. coli bacteria. Cadmium chalcogenide QDs provide the most attractive fluorescence labels in comparison with routine dyes or metal complexes. In contrast, nanospheres are more commonly used as carriers of fluorescence labels for fluorescence detection. Therefore, integration of fluorescent, water-soluble QDs into nanospheres provides a new generation of fluorescence markers for biological assays. Incorporation of same size
and/or differently sized nanocrystals (NC) into one bead will provide new pathways for fast and early detection systems since the emission spectra of QDs can be tuned to match practically any energy acceptor molecule by tailoring the size, shape, and composition of the QD. Hydrogels based on PNIPAM is a well known thermoresponsive polymer that undergoes a volume phase transition across the low critical solution temper
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