In Situ Fabrication of Cross‐Linked Protein Membranes by Using Microfluidics

Abstract

We report a novel technique for preparing cross-linked protein membranes within microchannels by using an interfacial cross-linking reaction. Glass microchannels with a Y input were assembled by using a simple adhesive bonding technique to achieve dual, parallel laminar flows. Membrane formation utilised an interfacial reaction at the liquid-liquid interface, which involved bovine serum albumin (aqueous solution with a flow rate of 300 microL min(-1)) and terephthaloyl chloride (xylene solution with a flow rate of 700 microL min(-1)), to form thin ( approximately 25 microm) cross-linked films along the length of the channel under the continuous pressure-driven laminar flow. Such microfabricated membranes could extend the separation potential of any microfluidic structure to provide a stable barrier layer. Furthermore, degradation of the membrane was possible by using an alkali sodium dodecyl sulfate solution, which led to the complete disappearance of the membrane. These membranes could facilitate additional modification to allow for different permeability properties by controlled degradation. The one-step in situ membrane-fabrication methodology reported here generated precisely localised membranes and avoided the complexities of subcomponent assembly, which require complicated alignment of small, preformed membranes. This methodology could become the basis for sophisticated microseparation systems, biosensors and several "lab-on-a-chip" devices.

Fundamentals and applications of immobilized microfluidic enzymatic reactors

“…There are now numerous examples of enzymatic microfluidic reactors with enzymes immobilized via carbodiimide linkage 74. cross‐linking by glutaraldehyde75–78 and activation by cyanogen bromide 79…”

Introduction of periodic boundary conditions into UNRES force field

“…Use of periodic boundary conditions (PBC) is necessary to reproduce the experimental observables that describe motion such as, for example, the diffusion constant in cross‐linked protein membranes . Implementation of PBC in molecular simulation algorithms is of constant interest, there has been improvement in treatment of electrostatic interactions in molecular .…”

Protein Capsules with Cross‐Linked, Semipermeable, and Enzyme‐Degradable Surface Barriers for Controlled Release

“…The thickness of the cross-linked layer was approximately 3.5 μm, which is one order of magnitude smaller than the values reported in other studies. [ 35,36 ] This difference can be attributed to a high cross-linking density in our system, which was caused by a high concentration of TCL (saturated in toluene). Once the surface layer was crosslinked, it would serve as a diffusion barrier, retarding the diffusion of TCL towards the interior.…”

“…Once the surface layer was crosslinked, it would serve as a diffusion barrier, retarding the diffusion of TCL towards the interior. [ 35 ] The cross-linked Figure 1. A) A schematic of the fl uidic device used for the fabrication of protein capsules via cross-linking of proteins at the oil/water interface.…”

“…The reaction involved a nucleophilic attack of the polarized carbon atom of TCL by the lone-pair electrons of the amino groups in the protein. [ 35 ] Immiscibility between the water and oil phases only allowed the polycondensation reaction to occur at the water-oil interface, [ 35,40 ] leading to the formation of a capsule with a thin, cross-linked shell.…”