**3. Conclusions**

in the absence of antibiotics, whereas in the presence of 3 μg/mL tetracycline for 8 h bacteria became filamentous [54]. Moreover, the mechanism of formation of long filamentous bacteria in the presence of cephalexin antibiotic was also studied with molecular biology

290 *Escherichia coli* Escherichia coli - Recent Advances on Physiology, Pathogenesis and Biotechnological Applications - Recent Advances on Physiology, Pathogenesis and Biotechnological Applications

In June 2016, it was reported the fabrication of tortuous-shaped giant magnetoimpedance (GMI) sensor (working frequency 2.2 MHz) integrated into a microfluidic device (MFD) (**Figure 11**) using a homemade gold nanofilm biofunctionalized with monoclonal anti *E. coli* antibodies, *E. coli* bacteria*/*biotinylated polyclonal antibodies*/*streptavidin-labeled superparamagnetic beads (2.8 μm) and sensitive and specific detection of different concentrations of

Electrochemically etched porous silicon (pSi) with ordered nanopore array integrated into a microfluidic PDMS channel was used for reflectivity effective optical thickness/fluorescence

to 107

strains) bacteria after their staining with a mixed solution of SYTO9 and propidium iodide, and confirmed by a significant pore blockage (specific) or any pore blockage (non specific)

Sputtered nanofibers (NFs) of different densities (one layer sparse or larger pore sizes, one layer dense or smaller pore sizes, two layer sparse, two layer dense, three layer sparse, and three layer dense) with either positive or negative charge were tested for maximizing the amount of *E. coli K12* cells retained. For microfluidic investigations, nanofiber multilayers

**Figure 11.** Tortuous-shaped giant magnetoimpedance (GMI) gold based-sensor for microfluidic detection of *E. coli.*

CFU/mL) and non specific (NOX and P17

techniques [55].

effects [30].

*E. coli* O157:H7 (50–500 CFU/mL) [54].

detection of specific *(E. coli,* ranging from 103

Paper microfluidics and smartphone technology were used for the detection of *E. coli* in real water sample using beads functionalized with anti *E. coli* antibodies predeposited in two out of a three channel paper device. It was found that by integration an internal gyroscope into a smartphone at an optimized angle of scatter detection, the presence of a single cell level in 90 s was possible [58]. Furthermore, a droplet-based, multiplexed fluorescence/light scatter submicron polystyrene particles functionalized with rabbit polyclonal anti K12 antibodies using nanofibrous substrate for the detection of 10<sup>2</sup> CFU/mL *E. coli* K-12 and *T*. *S. typhimurium* were reported in 2015. For experiments, all reagents were preimmobilized at fixed locations and included into two smartphones with necessary filters: one for incidence and the other for detection, positioned at 90° angle [59]. A microfluidic-cellulosic pad (μPAD) was loaded with polystyrene particles functionalized with polyclonal anti *E. coli* K12 antibodies and used for the detection of 10 CFU/mL *E. coli* K-12 in the human urine in about 30 s with a smartphone [60]. *E. coli* K-12 (101 CFU/mL) was detected in water sample (30 s) using also the principles of a μPAD-pad modified with antibodies coated particles and scattering intensity recorded by a smartphone with an autoexposure and autofocus locked on the central paper channel surface at 65° [61]. Identification of contaminated ground beef meat with various concentration of *E. coli* was possible without the need of functionalized particles with antibodies just by recording the resulted scattering light values at different angles with a smartphone after exposure to a perpendicular irradiation at 880 nm NIR-LED system. Therefore, different low detection limits were recorded: 101 CFU/mL at 45° and 10<sup>2</sup> CFU/mL at 30° and 60°. However, this method suffers from impossibility of distinguishing between different similar bacteria species (e.g., *E. coli* and *Salmonella* spp.) [62]. Moreover, the development of the first integrated paperbased DNA genosensor including nucleic acid extraction, amplification, and visual detection in about 1 h of *E. coli* (10–1000 CFU/mL) in spiked drinking water, milk, blood, and spinach using a smartphone was reported [63].

In conclusion, biosensors [62, 64, 65] and microfluidics [66] in combination with smartphone technology hold great hope that *E. coli* and various other coliforms may be detected in real time avoiding human suffering and save lives.
