Abstract: ** Lecture will be given in English**
Could have the solution for antibiotic-related dysbiosis been just under our feet all along? The very earth we walk upon contains an abundance of low-cost natural clay minerals, some are already FDA-approved, that exhibit intriguing nanomorphologies and high adsorption capacities, ideal for loading antimicrobials and their controlled release. One of the most prominent clay minerals investigated for that purpose is Halloysite nanotubes (HNTs). These 600-900 nm-long particles consist of alternating layers of silica and alumina, geologically rolled into a tube about 50 nm wide. The mesoporous inner lumen (15 nm inner diameter) enables the loading of guest molecules and their consequent hindered out-diffusion, while the outer silica surface readily adsorbs active compounds via electrostatic and ion-exchange interactions. Thus, we harness natural clay HNTs for the selective delivery of antimicrobials to target bacteria. First, the silica surface of HNTs is chemically immobilized with anti-E. coli antibodies, which are shown to increase their affinity to target bacteria by 2.5-fold as quantified by high-throughput imaging flow cytometry. Then, the modified clay is loaded with two separate antimicrobial payloads: (1) ciprofloxacin to be gradually released at the proximity of target bacteria and (2) plasmonic gold nanorods generating a localized photothermal effect under infra-red irradiation. The successful loading is evidenced at the nanoscale and a 2-4-fold superior antibacterial effect is demonstrated for the multifunctional nanoclay as investigated in a challenging heterogeneous culture.
We believe our HNTs-based design could serve as a generic cost-effective carrier for a variety of antimicrobials to be selectively guided against any microorganism of choice by facilely adjusting the immobilized capture probe.