الفهرس 
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Abstract
A facile hydrothermal technique was used to prepare sodium and hydrogen based titanate nanotubes at 6 and 23 hr. The crystalline structure of the prepared samples was verified by powder XRD diffraction analysis. The average crystallite sizes of STNT, HTNT, STNS and HTNS were calculated to be 32, 32, 64 and 64 nm respectively. As expected, No significant change in the average crystallite size was caused by hydrogen replacement. The BET surface area of STNT, HTNT, STNS and HTNS was calculated to be 114.57, 141.84, 96.48 and 135.9 m2/g respectively. For all samples the isotherm follows a type IV behaviour indicating the presence of mesoporous pores within all the samples. STNT, STNS, HTNT and HTNS showed a zeta potential of (-11.2, -11.7, 2.5 and 0.13 mV) respectively. The HRTEM images reveal that increasing the hydrothermal time from 6 to 23 hr enhanced the quality of the prepared nanotubes.
The experimental results indicated that STNT, STNS, HTNT and HTNS have an important antibacterial effect against different microorganisms causing serious infectious diseases in human and animals. In the present study, STNT, STNS, HTNT and HTNS showed good antibacterial activity at different concentrations against Gram Positive and Gram-negative bacteria besides antifungal activity with increasing antimicrobial activity towards the STNS sample than other prepared samples. The synthesized nanomaterials possessed a well-developed surface chemistry; chemical stability and the shape of the nanomaterials are the main factors responsible for the antimicrobial activity. With increasing the hydrothermal time to prepare Na-titanate nanotubes the following remarks were depicted. (i) average crystallite size was decreased from 64 nm at 6 hr to 32 nm at 23 hr. (ii) surface area was increased from 96 m2/g at 6 hr to 114 m2/g at 23 hr. (iii) the quality and length of the prepared nanotube was enhanced. We found that average diameter of nanotubes was decreased from 9.4 nm at 6 hr to 7.9 nm at 23 hr. while average length was increased from about 150 nm at 6 hr to about 600 nm at 23 hr. future considerations will be the focus of our research including studying cytocompatibility of nanotubes and testing them on other bacteria species. Immobilization of biomolecules over nanotubes and their antimicrobial efficiency will be studied in future work.