Study of albumin and fibrinogen membranes formed by interfacial crosslinking using microfluidic flow

Abstract

Microfluidics enables scale reduction in sample volume with obvious benefits for reagent conservation. In contrast to conventional macro-scale flow, microfluidics also offers unprecedented control over flow dynamics. In particular, laminar flow is readily achieved, allowing for new analytical and synthetic strategies. Here, two parallel flows of buffer and xylene were used to create a stable liquid-liquid interface within linear micro-channels. These, respectively, carried protein (albumin or fibrinogen) and an acyl chloride to effect protein crosslinking. This created robust, micro-membranes at the interface that bisected the fluid channel. Membrane formation was self-limiting, with fibrinogen membranes showing greater solute permeability than albumin, based on dye transport (Ponceau S, Meldola Blue). The crosslinker isophthaloyl dichloride led to thinner, less permeable membranes than terephthaloyl chloride. Larger surface area membranes formed at a static liquid-liquid interface served as a more physically accessible model and allowed precise electrochemical determination of acetaminophen, catechol and peroxide diffusion coefficients, which confirmed the greater fibrinogen permeability. Scanning electron microscopy (SEM) of the membranes also indicated a higher population of discrete nanopores at the fibrinogen surface. A crosslinking pH had a strong effect on overall permeability. Adhesion of B50 neuronal cells was demonstrated, and it is proposed that the membranes could facilitate cell growth through bidirectional nutrient supply in a micrbioreactor format.

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

“…A magnified image taken from the boxed region (Figure C) demonstrates that the more or less spherical pores in the interior were approximately 3 μm in diameter and a dense layer was formed at the surface due to the cross‐linking reaction. 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 . 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).…”

“…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.…”

“…Immiscibility between the water and oil phases leads to the formation of water‐in‐oil emulsion droplets with uniform sizes . A surface barrier will be formed when there is a polycondensation reaction between amine groups of the protein and a cross‐linker, diacyl chloride added to the oil phase, at the interface between the water and oil phases . We used albumin as an example to demonstrate the concept because of its excellent biocompatible and biodegradable (activated by pepsin) property, as well as its capability to resist opsonization…”

Microfluidic and Microscale Assays to Examine Regenerative Strategies in the Neuro Retina

“…Notably, these phenomena include, but are not limited to: (i) Laminar flow, where movement of fluids transmits dissipative forces proportional to the flow rate [29][30][31][32] (ii) Interfacial forces, were the attractive forces between molecules at the interface of two or more fluids are equal to zero [33][34][35] (iii) Capillary action, which enables fluids to flow within narrow spaces of porous materials without the assistance of external forces [27,[36][37][38] and (iv) Electrokinesis, where an imposed electric field induces fluidic transport [39,40]. In addition, devices fabricated at the microscale provide the remarkable advantage of precise experimental validation against analytical models of molecular and convective transport [41,42], viscoelasticity [43][44][45], electrochemical dynamics [46,47] and many others [48][49][50][51][52]. These advantages have pioneered the development of single and multiplexed microfluidic channels [53][54][55], micropatterned substrate surfaces [56][57][58][59], and three-dimensional (3D) microfabricated structures [60,61] to examine localized cell behavior.…”

Adsorption and conformational modification of fibronectin and fibrinogen adsorbed on hydroxyapatite. A QCM‐D study

“…11 However, a vast amount of literature generated in recent years on the topic of protein adhesion to materials has yield a "striking" lack of consensus so extreme that no general conclusions can be extracted on the subject of material design parameters that favors protein adhesion. [12][13][14][15][16][17][18] Only a general rule that a low crystal size/low particle size favor bone regenation while a high crystallinity favors bone resorption 19 and a common agreement on the importance of roughness 20 are generally acknowledged. However, the design of materials for bone regeneration requires a better understanding of the adsorption of serum proteins to those materials.…”