Synthesis and immobilization of silver nanoparticles on aluminosilicate nanotubes and their antibacterial properties

New multifunctional nanoparticle–nanotube hybrid systems, due to their unique and superior properties compared with their pure counterparts, increasingly forming the foundation of transformational developments in areas as diverse as electronics, photonics, catalysis, biotechnology, and energy storage among many other applications (Wu et al. 2011 ; Mackiewicz et al. 2008 ; Georgakilas et al. 2007 ; Kong et al. 2007 ; Li et al. 2009 ). Single-walled aluminosilicate nanotubes (AlSiNTs) are excellent candidates for fabricating various functional nanohybrid materials due to their well-defined one-dimensional structure (Yucelen et al. 2011 ; Thill et al. 2012 ), vast range of tunable compositions (Avellan et al. 2014 ), functionalizable surfaces (Kang et al. 2011 ), attainability in pure form without a catalyst (Yucelen et al. 2011 ), and ability to readily form hydrogels, transparent films, powders, and coatings (Jiravanichanun et al. 2011 ; Kang et al. 2012 ; Kuroda et al. 2012 ). As shown in Fig. 1 a, b, AlSiNTs have ordered wall structure that is identical to a layer of aluminum (III) hydroxide (gibbsite) with tetrahedral silanol (≡Si–OH) groups attached at the inner side. Outer diameter of AlSiNTs is around 2.2 nm, while their average length is about 100 nm. AlSiNTs form colloidal three-dimensional (3D) networks of hexagonally packed bundles due to entanglement and hydrogen bonding among the nanotubes (Fig. 1 c). One can easily obtain a variety of AlSiNT structures (Thill et al. 2012 ; Avellan et al. 2014 ; Kang et al. 2011 ), or achieve precise control over dimensional and morphological parameters by replacing the Si source (Boyer et al. 2014 ; Levard et al. 2010 ) and use different acids (Yucelen et al. 2012 ) during their aqueous phase synthesis, which presents new possibilities for a number of applications involving, but not limited to, molecular transport (Kang et al. 2011 ), bio-molecular sensing (Jiravanichanun et al. 2011 ), molecular separation (Kang 2012 ), and bone tissue engineering (Ishikawa et al. 2010 ).