Effect of different modified nanoclays on the kinetics of preparation and properties of polymer-based nanocomposites

Toxicity evaluations of nanoclays and thermally degraded byproducts through spectroscopical and microscopical approaches

BACKGROUND

Montmorillonite is a type of nanoclay that originates from the clay fraction of the soil and is incorporated into polymers to form nanocomposites with enhanced mechanical strength, barrier, and flammability properties used for food packaging, automotive, and medical devices. However, with implementation in such consumer applications, the interaction of montmorillonite-based composites or derived byproducts with biological systems needs to be investigated.

METHODS

Herein we examined the potential of Cloisite Na⁺ (pristine) and Cloisite 30B (organically modified montmorillonite nanoclay) and their thermally degraded byproducts' to induce toxicity in model human lung epithelial cells. The experimental set-up mimicked biological exposure in manufacturing and disposal areas and employed cellular treatments with occupationally relevant doses of nanoclays previously characterized using spectroscopical and microscopical approaches. For nanoclay-cellular interactions and for cellular analyses respectively, biosensorial-based analytical platforms were used, with induced cellular changes being confirmed via live cell counts, viability assays, and cell imaging.

RESULTS

Our analysis of byproducts' chemical and physical properties revealed both structural and functional changes. Real-time high throughput analyses of exposed cellular systems confirmed that nanoclay induced significant toxic effects, with Cloisite 30B showing time-dependent decreases in live cell count and cellular viability relative to control and pristine nanoclay, respectively. Byproducts produced less toxic effects; all treatments caused alterations in the cell morphology upon exposure.

CONCLUSIONS

Our morphological, behavioral, and viability cellular changes show that nanoclays have the potential to produce toxic effects when used both in manufacturing or disposal environments.

GENERAL SIGNIFICANCE

The reported toxicological mechanisms prove the extensibility of a biosensorial-based platform for cellular behavior analysis upon treatment with a variety of nanomaterials.

Polystyrene-grafted graphene nanoplatelets with various graft densities by atom transfer radical polymerization from the edge carboxyl groups

An initiator containing modifier, 4-hydroxybutyl 2-bromopropionate (CBr), was synthesized by the reaction of 1,4-butanediol and alpha-bromoisobutyryl bromide. Subsequently, graphene oxide was functionalized with CBr to yield initiator-anchored graphene (GCBr). Then, GCBr was used as the precursor for ATRP of styrene.

Nanocrystalline cellulose grafted random copolymers of N-isopropylacrylamide and acrylic acid synthesized by RAFT polymerization: effect of different acrylic acid contents on LCST behavior

NCC-attached dual-sensitive copolymers of N-isopropylacrylamide and acrylic acid (AA) with different contents of AA were synthesized by RAFT polymerization. Effect of NCC, AA content, and pH on LCST was evaluated.