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In this study, a biological evaluation of the antimicrobial activity of Zn-doped titania nanofibers was carried out using Escherichia coli ATCC 52922 (Gram negative) and Staphylococcus aureus ATCC 29231 (Gram positive) as model organisms. The utilized Zn-doped titania nanofibers were prepared by the electrospinning of a sol-gel composed of zinc nitrate, titanium isopropoxide, and polyvinyl acetate; the obtained electrospun nanofibers were vacuum dried at 80°C and then calcined at 600°C. The physicochemical properties of the synthesized nanofibers were determined by X-ray diffraction pattern, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron probe microanalysis, thermogravimetry, and transmission electron microscopy (TEM). The antibacterial activity and the acting mechanism of Zn-doped titania nanofibers against bacteria were investigated by calculation of minimum inhibitory concentration and analyzing the morphology of the bacterial cells following the treatment with nanofibers solution. Our investigations reveal that the lowest concentration of Zn-doped titania nanofibers solution inhibiting the growth of S. aureus ATCC 29231 and E. coli ATCC 52922 strains is found to be 0.4 and 1.6 μg/ml, respectively. Furthermore, Bio-TEM analysis demonstrated that the exposure of the selected microbial strains to the nanofibers led to disruption of the cell membranes and leakage of the cytoplasm. In conclusion, the combined results suggested doping promotes antimicrobial effect; synthesized nanofibers possess a very large surface-to-volume ratio and may damage the structure of the bacterial cell membrane, as well as depress the activity of the membranous enzymes which cause bacteria to die in due course.

We explored electrospinning as a feasible and practicable mode for encapsulation and stabilization of Lactobacillus gasseri. The utilized nanocomposite was prepared using sol-gel composed of animate L. gasseri and inanimate PVA. The objective was to examine the ability of electrospinning method to protect functional properties of probiotic L. gasseri. The PVA was used as an encapsulation matrix as it is biocompatible and hydrophilic in nature thus facilitate an easy revival of bacteria. The characterization of as-spun bioproduct was done by energy-dispersive X-ray spectrometer, SEM, and TEM, whereas thermal behavior was analyzed by thermogravimetry. The viability was confirmed by traditional pour plate method and fluorescence microscopy. Furthermore, to test whether the functionality of L. gasseri was affected, the encapsulated L. gasseri were fed to mouse for colonization. Our results pointed out that encapsulated bacteria were viable for months, and their metabolism was not affected by immobilization; thus, they could be used in food engineering and trade.