A fully automated microfluidic-based electrochemical sensor for real-time bacteria detection.

A fully automated microfluidic-based electrochemical biosensor was designed and manufactured for pathogen detection. The quantification of Escherichia coli was investigated with standard and nanomaterial amplified immunoassays in the concentration ranges of 0.99 × 1043.98 × 109 cfu mL-1 and 103.97 × 107 cfu mL-1 which resulted in detection limits of 1.99 × 104 cfu mL-1 and 50 cfu mL-1, respectively. The developed methodology was then applied for E. coli quantification in water samples using nanomaterial modified assay. Same detection limit for E. coli was achieved for real sample analysis with a little decrease on the sensor signal. Cross-reactivity studies were conducted by testing Shigella, Salmonella spp., Salmonella typhimurium and Staphylococcus aureus on E. coli specific antibody surface that confirmed the high specificity of the developed immunoassays. The sensor surface could be regenerated multiple times which significantly reduces the cost of the system. Our custom-designed biosensor is capable of detecting bacteria with high sensitivity and specificity, and can serve as a promising tool for pathogen detection.

Lab-on-a-chip based biosensor for the real-time detection of aflatoxin.

Polymers were synthesized and utilized for aflatoxin detection coupled with a novel lab-on-a-chip biosensor: MiSens and high performance liquid chromatography (HPLC). Non-imprinted polymers (NIPs) were preferred to be designed and used due to the toxic nature of aflatoxin template and also to avoid difficult clean-up protocols. Towards an innovative miniaturized automated system, a novel biochip has been designed that consists of 6 working electrodes (1mm diameter) with shared reference and counter electrodes. The aflatoxin detection has been achieved by a competition immunoassay that has been performed using the new biochips and the automated MiSens electrochemical biosensor device. For the assay, aflatoxin antibody has been captured on the Protein A immobilized electrode. Subsequently the sample and the enzyme-aflatoxin conjugate mixture has been injected to the electrode surfaces. The final injection of the enzyme substrate results in an amperometric signal. The sensor assays for aflatoxin B1 (AFB1) in different matrices were also performed using enzyme link immunosorbent assay (ELISA) and HPLC for confirmation. High recovery was successfully achieved in spiked wheat samples using NIP coupled HPLC and NIP coupled MiSens biosensor [2ppb of aflatoxin was determined as 1.86ppb (93% recovery), 1.73ppb (86.5% recovery), 1.96ppb (98% recovery) and 1.88ppb (94.0% recovery) for immunoaffinity column (IAC)-HPLC, NIP-HPLC, Supel™ Tox SPE Cartridges (SUP)-HPLC and NIP-MiSens, respectively]. Aflatoxin detection in fig samples were also investigated with MiSens biosensor and the results were compared with HPLC method. The new biosensor allows real-time and on-site detection of AFB1 in foods with a rapid, sensitive, fully automated and miniaturized system and expected to have an immense economic impact for food industry.

An integrated lab-on-a-chip-based electrochemical biosensor for rapid and sensitive detection of cancer biomarkers.

Recent advances in the area of biosensor technology and microfluidic applications have enabled the miniaturisation of the sensing platforms. Here we describe a new integrated and fully automated lab-on-a-chip-based biosensor device prototype (MiSens) that has potential to be used for point-of-care cancer biomarker testing. The key features of the device include a new biochip, a device integrated microfluidic system and real-time amperometric measurements during the flow of enzyme substrate. For ease of use, a new plug and play type sensor chip docking station has been designed. This system allows the formation of an ∼7 µL capacity flow cell on the electrode array with the necessary microfluidic and electronic connections with one move of a handle. As a case study, the developed prototype has been utilised for the detection of prostate-specific antigen (PSA) level in serum that is routinely used as a biomarker for the diagnosis of prostate cancer. The patient samples from a nearby hospital have been collected and tested using the MiSens device, and the results have been compared to the hospital results. The obtained results indicate the potential of the MiSens device as a useful tool for point-of-care testing. Graphical abstract Microfluidics integrated and automated electrochemical biosensor device "MiSens" has been designed and fabricated by a multidisciplinary team and utilised to detect PSA from clinical samples.