Gold Nanorod-Incorporated Halloysite Nanotubes Functionalized with Antibody for Superior Antibacterial Photothermal Treatment

Abstract

The global spread of antibiotic-resistant strains, and the need to protect the microflora from non-specific antibiotics require more effective and selective alternatives. In this work, we demonstrate for the first time a superior antibacterial photothermal effect of plasmonic gold nanorods (AuNRs) via their incorporation onto natural clay halloysite nanotubes (HNTs), which were functionalized with anti-E. coli antibodies (Ab-HNTs). AuNRs were incorporated onto the Ab-HNTs through a facile freeze–thaw cycle, and antibody integrity following the incorporation was confirmed via infrared spectroscopy and fluorescence immunolabeling. The incorporation efficiency was studied using UV-Vis absorption and transmission electron microscopy (TEM). Mixtures of E. coli and AuNR-Ab-HNTs hybrids or free AuNRs were irradiated with an 808 nm laser at 3–4 W cm−2, and the resulting photothermal antibacterial activity was measured via plate count. The irradiated AuNR-Ab-HNTs hybrids exerted an 8-fold higher antibacterial effect compared to free AuNR under 3.5 W cm−2; whereas the latter induced a 6 °C-higher temperature elevation. No significant antibacterial activity was observed for the AuNR-Ab-HNTs hybrid against non-target bacteria species (Serratia marcescens and Staphylococcus epidermidis). These findings are ascribed to the localization of the photothermal ablation due to the binding of the antibody-functionalized clay to its target bacteria, as supported through TEM imaging. In the future, the HNTs-based selective carriers presented herein could be tailored with other antibacterial nanoparticles or against another microorganism via the facile adjustment of the immobilized antibody.

Photochemical Strategies toward Precision Targeting against Multidrug-Resistant Bacterial Infections

“…Similarly, Setter et al adopted surface-conjugated protein A to functionalize the gold nanorod-incorporated halloysite nanotubes with anti-E. coli antibodies. 200 After 808 nm NIR irradiation, the AuNR-Ab-HNTs hybrids exhibited 8fold higher killing efficiency against E. coli than bare AuNR, with little impact on the survival of nontarget S. marcescens and S. epidermidis strains. Meanwhile, the temperature increase in the antibody-conjugated group is in fact modest, 6 °C lower than bare AuNR.…”

“…Meanwhile, the temperature increase in the antibody-conjugated group is in fact modest, 6 °C lower than bare AuNR. 200 Also, after cotreatment with H 2 O 2 (0.4 mM) and 808 nm NIR irradiation (1 W cm −2 , 5 min), 5 × 10 5 −10 6 CFU mL −1 of S. aureus was fully sterilized by anti-S. aureus antibody linked Ab-Au/Ir@Cu/Zn-MOF at a nanocomposite concentration as low as 6.25 μg mL −1 . 201 6.3.…”

“…After 808 nm NIR irradiation, the AuNR-Ab-HNTs hybrids exhibited 8-fold higher killing efficiency against E. coli than bare AuNR, with little impact on the survival of nontarget S. marcescens and S. epidermidis strains. Meanwhile, the temperature increase in the antibody-conjugated group is in fact modest, 6 °C lower than bare AuNR . Also, after cotreatment with H 2 O 2 (0.4 mM) and 808 nm NIR irradiation (1 W cm –2 , 5 min), 5 × 10 5 –10 6 CFU mL –1 of S. aureus was fully sterilized by anti- S. aureus antibody linked Ab-Au/Ir@Cu/Zn-MOF at a nanocomposite concentration as low as 6.25 μg mL –1 …”

Recent Advances of Halloysite Nanotubes in Biomedical Applications

“…Prinz Setter [87] Au; Antibody Targeted antibacterial effect; Synergistic effect with photothermal therapy AuNR-Ab-HNTs Functionalize HNT with Anti-E. coli antibody and then incorporate AuNR through a facile freeze-thaw cycle.…”

“…Prinz Setter's group introduced a highly innovative approach by functionalizing HNTs with anti‐ E. coli antibodies, endowing the material with selective binding to E. coli bacteria. [ 87 ] The incorporation of AuNR bestowed superior and targeted antibacterial photothermal activity, culminating in a remarkable reduction of up to five orders of magnitude in the E. coli population.…”