Patenting trends in enzyme related microfluidic applications

Synthesis of alginate-silica hybrid hydrogel for biocatalytic conversion by β-glucosidase in microreactor

The organic-inorganic hybrid materials have been used in different fields to immobilize biomolecules since they offer many advantages. The aim of this study was to optimize and characterize the alginate-silica hybrid hydrogel as a stable and injectable form for microfluidic systems using internal gelation method and increase the stability and activity of immobilized enzyme for biocatalytic conversions as well. Characterization was carried out by scanning electron microscopy, energy dispersive spectroscopy/mapping, Brunauer-Emmett-Teller, Barrett-Joyner-Halenda, and Fourier-transform infrared spectroscopy analyses, and the shrinkages of monoliths were evaluated. Subsequent to optimizing the enzyme concentration (40 μg), hydrolytic conversion of 4-nitrophenyl β-d-glucopyranoside (pNPG) was performed to understand the behavior of the bioconversion in the microfluidic system. The yield was 94% which reached the equilibrium at 24 h indicating that the alginate-silica gel derived microsystem overcome some drawbacks of monolithic systems. Additionally, bioconversion of Ruscus aculeatus saponins was carried out at the same setup in order to obtain aglycon part, which has pharmaceutical significance. Although pure aglycon could not be achieved, an intermediate compound was obtained based on the HPLC analysis. The developed formulation can be utilized for various life science applications.

Cytotoxic responses of carnosic acid and doxorubicin on breast cancer cells in butterfly-shaped microchips in comparison to 2D and 3D culture

Two dimensional (2D) cell culture systems lack the ability to mimic in vivo conditions resulting in limitations for preclinical cell-based drug and toxicity screening assays and modelling tumor biology. Alternatively, 3D cell culture systems mimic the specificity of native tissue with better physiological integrity. In this regard, microfluidic chips have gained wide applicability for in vitro 3D cancer cell studies. The aim of this research was to develop a 3D biomimetic model comprising culture of breast cancer cells in butterfly-shaped microchip to determine the cytotoxicity of carnosic acid and doxorubicin on both estrogen dependent (MCF-7) and independent (MDA-MB231) breast cancer cells along with healthy mammary epithelial cells (MCF-10A) in 2D, 3D Matrigel™ and butterfly-shaped microchip environment. According to the developed mimetic model, carnosic acid exhibited a higher cytotoxicity towards MDA-MB 231, while doxorubicin was more effective against MCF-7. Although the cell viabilities were higher in comparison to 2D and 3D cell culture systems, the responses of the investigated molecules were different in the microchips based on the molecular weight and structural complexity indicating the importance of biomimicry in a physiologically relevant matrix.

An injectable alginate-based hydrogel for microfluidic applications

The objective of this study was to develop an injectable alginate based formulation for immobilizing enzymes into microfluidic systems. The gelation was induced upon lowering the pH by addition of d-glucono-δ-lactone (GDL) and release of Ca⁺ ions from solid CaCO₃. The effects of GDL concentration on enzymatic activity and gelation time were investigated. The results indicated that increasing the GDL concentration increased both surface area and enzymatic activity. Also, chitosan was added to the formulation at different ratios to enhance the stability of enzyme during immobilization. For microfluidic application, 100μl spiral coil single channel microchip was fabricated and alginate GDL mixture containing β-glucosidase was injected to the microchannel prior to gelation. Enzymatic conversion was performed by pumping substrate (pNPG) through the microchannel. The results indicated that the entire substrate was converted continuously during 24h without any leakage or deactivation of immobilized enzyme.

Diffusion phenomena of cells and biomolecules in microfluidic devices

Biomicrofluidics is an emerging field at the cross roads of microfluidics and life sciences which requires intensive research efforts in terms of introducing appropriate designs, production techniques, and analysis. The ultimate goal is to deliver innovative and cost-effective microfluidic devices to biotech, biomedical, and pharmaceutical industries. Therefore, creating an in-depth understanding of the transport phenomena of cells and biomolecules becomes vital and concurrently poses significant challenges. The present article outlines the recent advancements in diffusion phenomena of cells and biomolecules by highlighting transport principles from an engineering perspective, cell responses in microfluidic devices with emphases on diffusion- and flow-based microfluidic gradient platforms, macroscopic and microscopic approaches for investigating the diffusion phenomena of biomolecules, microfluidic platforms for the delivery of these molecules, as well as the state of the art in biological applications of mammalian cell responses and diffusion of biomolecules.