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We develop a multivalent aptamer meshed open pore membrane with a signal amplification method as a simple and robust platform for sensitive, robust, and high-flux detection of E. coli O157:H7 whole cells in food samples. Nylon open pore membranes are surface modified by multi-handled poly(amidoamine) dendrimers as templates that are subsequently functionalized with multiple branches of capturing RCA (cRCA). The resulting cRCA networks are composed of tandem repeating aptamers that can specifically recognize and capture E. coli O157:H7 cells. The captured cells are then conjugated with signaling RCA (sRCA) to amplify the fluorescent detection signal. Our results demonstrate that the cRCA-based aptamer meshwork significantly enhances the surface-capturing performance of E. coli O157:H7 cells while achieving high-fluxes. Moreover, the membrane surface modification using dendrimers renders the resulting membrane nonfouling thus significantly reducing the background noises by approximately 96 times while the sRCA signal intensification enhances the fluorescent detection signals by approximately 27 times. We show that the membranes exhibit excellent performances in detecting E.coli O157:H7 in milk and orange juice samples with limit of detection of 10 cells per 250 mL with excellent specificity, offering a robust and practical approach for rapid and sensitive detection of foodborne bacteria. • Membrane allows high flux detection of bacteria in complex food matrices. • Dendrimer surface modification decreases detection background noises. • Dendrimer multi-handle templates allow formation of aptamer network on the membrane. • cRCA products mesh the membrane open pores to enhance target capturing. • sRCA signal intensification amplifies detection signals for sensitive detection. [ABSTRACT FROM AUTHOR]

Herein, we introduced a molecular imprinting based capacitive biosensor for real-time and highly sensitive bacteriophage detection. The sensing mechanism was based on the binding of target phage into the specific cavities on the electrode surface which resulted in a measurable change in the total capacitance of the system. Phage detection was investigated in the concentration range of 1.0 × 10 1 –1.0 × 10 5 plaque forming units (pfu)/mL and the limit of detection (LOD) was measured as 10 pfu/mL which shows the high sensitivity of the system compared to results reported for previous studies. The system also allowed the detection of phages in river water samples which is very important for the usability of the system as in-field analysis for different applications e.g. investigating the contamination of drinking water via wastewater or reservoir water in the future. Recently, due to their high specificity towards their host bacteria, being cost-effective and also stable in harsh environments, bacteriophages have been used as biorecognition elements in many studies. Due to this reason, the applicability of the phage imprinted biosensor was also investigated for host bacteria detection. E. coli detection has been performed in the concentration range of 1.0 × 10 2 –1.0 × 10 7 colony forming units (cfu)/mL with a LOD value of 100 cfu/mL. This system offers direct, real-time, very sensitive and rapid detection of bacteriophage and its host bacteria. [ABSTRACT FROM AUTHOR]

In this paper, we report a single step solid phase synthesis strategy for colistin modified fluorescent carbon dots (CDs@colistin) for the selective detection of gram-negative bacteria like Escherichia coli . Colistin is a well known cyclic polypeptide antibiotic drug but here we have used as a binding ligand for E. coli. Here also, the synthesised CDs@colistin are used for selective Fe 3+ metal ion detection. The detection limits are 460 cfu/mL for E. coli and 56 nM for Fe 3+ with a linear range of 3.81 × 10 2 –2.44 × 10 4 cfu/mL and 0–48 μM, respectively. The synthesised CDs@colistin are well dispersed in water with an uniform particle size ranging from 2 nm to 5 nm executing high quantum yield of 7.56%. The synthesis process of CDs@colistin is simple, cheap, and less time consuming. Simultaneously, we have applied CDs@colistin as a novel probe for E. coli detection in three different real samples like human urine, apple juice, and tap water to evaluate the practical applicability of the synthesised colistin conjugated carbon dots. [ABSTRACT FROM AUTHOR]

This paper reports an experimental study of E. coli sensing based on surface-skimming-bulk-wave delay line device fabricated on ST-cut quartz. The sensor configuration consisted of an 87.7 MHz oscillator with the delay line as control element in its feedback loop. The antigen–antibody immunochemical reaction was employed on the acoustic wave device surface to generate mass loading and frequency shift. The sensor output was monitored by an RF spectrum analyzer. Highly specific sensing is demonstrated for E. coli cells up to 0.4 cells/μl in water. The methodology offers possibility for developing highly sensitive and fast E. coli sensors for testing of water potability. [Copyright &y& Elsevier]