As the research of nanoclay progresses, its applicability has transcended from mere material science to boarder biotechnological solutions. One good example for this trend are Halloysite nanotubes (HNTs). These 600-900 nm-long clay particles exhibit an intrinsic mesoporosity (inner dimeter of ca. 15 nm), orthogonal alumina-silica chemistry as well as a unique bio-nano interface. Thus, the virtues of HNTs have been exploited for many bioapplications from tissue engineering through antimicrobial activity to controlled drug delivery. In our research, we endeavor to combine the two latter avenues by utilizing HNTs for the selective delivery of antimicrobials to target bacteria. Such a design could be useful in neutralizing only a specific species in a heterogenous population avoiding dysbiosis. Selective binding of HNTs to target bacteria (E. coli) is realized by the immobilization of properly oriented anti E. coli antibodies onto the HNTs surface. The antibacterial effect is exerted by the release of an antibiotic payload (ciprofloxacin). HNTs surface modification starts with their acidic etching enhancing their porosity, and exposing additional silanol groups on their surface. The OH groups are then amino-silanized and subsequently carboxylated towards the surface conjugation of protein A onto which antibodies are anchored at a proper orientation. Finally, an antibiotic cargo is loaded into the antibody-modified HNTs to be gradually released at the proximity of the target bacteria. The multifunctional HNTs are extensively characterized by a set of physiochemical techniques such as FTIR-ATR, zeta potential measurement, TGA and electron microscopy. In addition, their activity is investigated by biologically oriented methods including fluorescence microscopy and high-throughput imaging flow cytometry.

Halloysite nanotubes for targeting bacterial cells

ACS Spring Meeting 2021

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