Under-5-Minute Immunoblot Assays by Vortex Fluidic Device Acceleration

Unlocking the potential of personalized medicine in point-of-care settings requires a new generation of biomarker and proteomic assays. Ideally, assays could inexpensively perform hundreds of quantitative protein measurements in parallel at the bedsides of patients. This goal greatly exceeds current capabilities. Furthermore, biomarker assays are often challenging to translate from benchtop to clinic due to difficulties achieving and assessing the necessary selectivity, sensitivity, and reproducibility. To address these challenges, we developed an efficient (<5 min), robust (comparatively lower CVs), and inexpensive (decreasing reagent use and cost by >70 %) immunoassay method. Specifically, the immunoblot membrane is dotted with the sample and then developed in a vortex fluidic device (VFD) reactor. All assay steps-blocking, binding, and washing-leverage the unique thin-film microfluidics of the VFD. The approach can accelerate direct, indirect, and sandwich immunoblot assays. The applications demonstrated include assays relevant to both the laboratory and the clinic.

Enzymatic Bioreactors: An Electrochemical Perspective

Biocatalysts provide a number of advantages such as high selectivity, the ability to operate under mild reaction conditions and availability from renewable resources that are of interest in the development of bioreactors for applications in the pharmaceutical and other sectors. The use of oxidoreductases in biocatalytic reactors is primarily focused on the use of NAD(P)-dependent enzymes, with the recycling of the cofactor occurring via an additional enzymatic system. The use of electrochemically based systems has been limited. This review focuses on the development of electrochemically based biocatalytic reactors. The mechanisms of mediated and direct electron transfer together with methods of immobilising enzymes are briefly reviewed. The use of electrochemically based batch and flow reactors is reviewed in detail with a focus on recent developments in the use of high surface area electrodes, enzyme engineering and enzyme cascades. A future perspective on electrochemically based bioreactors is presented.

Vortex fluidic mediated food processing

The high heat and mass transfer, and controlled mechanoenergy, in angled vortex fluidics has been applied in chemical and material sciences and allied fields, but its utility in food processing remains largely unexplored. Herein we report three models of food processing incorporating such vortex fluidics, including enzymatic hydrolysis, raw milk pasteurization and encapsulation. The processing times of enzymatic hydrolysis was reduced from about 2–3 hours to 20 minutes, with the processing time of raw milk pasteurization reduced from 30 to 10 minutes, and an encapsulated particle size reduced approximately 10-fold, from micro meters to hundreds of nanometers. These findings highlight exciting possibilities, in exploiting the value of vortex fluidic mediated processing in the food industry.

Self-Assembling All-Enzyme Hydrogels for Flow Biocatalysis

Continuous flow biocatalysis is an emerging field of industrial biotechnology that uses enzymes immobilized in flow channels for the production of value-added chemicals. We describe the construction of self-assembling all-enzyme hydrogels that are comprised of two tetrameric enzymes. The stereoselective dehydrogenase LbADH and the cofactor-regenerating glucose 1-dehydrogenase GDH were genetically fused with a SpyTag or SpyCatcher domain, respectively, to generate two complementary homo-tetrameric building blocks that polymerize under physiological conditions into porous hydrogels. Mounted in microfluidic reactors, the gels show excellent stereoselectivity with near quantitative conversion in the reduction of prochiral ketones along with high robustness under process and storage conditions. The gels function as compartment that retains intermediates thus enabling high total turnover numbers of the expensive cofactor NADP(H).

Vortex Fluidic Chemical Transformations

Driving chemical transformations in dynamic thin films represents a rapidly thriving and diversifying research area. Dynamic thin films provide a number of benefits including large surface areas, high shearing rates, rapid heat and mass transfer, micromixing and fluidic pressure waves. Combinations of these effects provide an avant-garde style of conducting chemical reactions with surprising and unusual outcomes. The vortex fluidic device (VFD) has proved its capabilities in accelerating and increasing the efficiencies of numerous organic, materials and biochemical reactions. This Minireview surveys transformations that have benefited from VFD-mediated processing, and identifies concepts driving the effectiveness of vortex-based dynamic thin films.