Preliminary Development of a Magnetically Assisted Test Strip (MATS) Cartridge and Fluorescent DNA Aptamer-Magnetic Bead Quantum Dot Sandwich Assays for Multiplexed Food Safety Applications

Abstract

Preliminary development of a simple mesofluidic multi-channel plastic cartridge with underlying external magnet to drag DNA aptamer-coated paramagnetic beads through fluids in the channels while developing a sandwich assay with quantum dot-conjugated reporter aptamers is described. This approach is superior to traditional lateral flow test strips in several ways including: 1) the ability to control the speed of lateral flow in the channel versus conventional nitrocellulose analytical membranes with fixed wicking times. 2) The use of aptamers for potentially greater affinity and consistency from batch-to-batch versus comparable antibodies. 3) Superior fluorescence efficiency and intensity provided by quantum dots versus conventional fluorescent dyes and 4) the ability to multiplex based on the various colored emissions of different sized quantum dots when excited with a single ultraviolet source. Development of the system from concept to prototype is described along with illustration of sensitive system performance for several food safety-related targets. The system is also clearly adaptable to rapid multiplex detection and sensitive quantitation of clinical biomarkers, drugs, environmental, veterinary or other target analytes.

The Diversity of a Polyclonal FluCell‐SELEX Library Outperforms Individual Aptamers as Emerging Diagnostic Tools for the Identification of Carbapenem Resistant Pseudomonas aeruginosa

“…In contrast for C1R1 the k D was 31(±2) n m and a Hill coefficient of n =5.1 which is typical for a cooperative binding mode [22] suggesting that C1R1 requires relatively high concentrations to obtain full experimental functionality (Figure 2 D). Commonly the limit of detection (LOD) for cells or individual proteins is estimated by quantifying the aptamer binding to a decreasing amount of target [23–25] . Both, the library R16 and C1R1, thereby delivered fluorescence signals above the detection limit for the reference strain P. aeruginosa PAO1, which was calculated as three standard deviations from the mean blank value.…”

“…Commonly the limit of detection (LOD) for cells or individual proteins is estimated by quantifying the aptamer binding to ad ecreasing amount of target. [23][24][25] Both, the library R16 and C1R1, thereby delivered fluorescences ignals above the detection limit for the reference strain P. aeruginosa PAO1,w hich was calculated as three standard deviationsf rom the mean blank value. With 250 cells as the lowest measured cell number ar easonable limit of detection for diagnostic applications was achieved (Figure 3E).…”