Flow Analysis of Regenerated Silk Fibroin/Cellulose Nanofiber Suspensions via a Bioinspired Microfluidic Chip

Abstract

The outstanding performance of silk, especially in terms of mechanical properties, can be attributed to the sophisticated silk gland and specialized spinning method that exists in nature. In addition, the gland, with decreasing diameter, has been proven to be an outstanding actuator of the sophisticated spinning system. [5,9] It has been qualitatively demonstrated that a region of contracting geometry of the S-shaped duct of silk gland can induce stretching of protein molecules, phase separation, and self-assembly due to shear and elongation flow. [10][11][12][13][14][15] During the subsequent spinning process in air, the protein ultimately aggregates into fibers with spectacular and distinctive properties. However, the mechanisms within the glands with exponential decaying diameter and their ability to dynamically change the conformation of the proteins is yet to be elucidated. [6] At present, various biomimetic spinning methods have been used to fabricate high-performance artificial silk and reveal the relationship between the spinning channel and silk performance. For example, the microfluidic device with miniaturized channels of designed configurations can easily control the physicochemical microenvironment, while using trace amounts of reagents. [6,10,[16][17][18][19][20] The sophisticated, compact, and highly functional microfluidic devices have been widely used to understand the geometry confinements, control overflow, and synthesis of artificially regenerated silk fibroin (RSF) fibers. [21][22][23][24][25][26][27][28][29][30] For example, Rammensee et al. prepared assembled spider dragline silk fibers through a microfluidic device. [31] Kinahan et al. adopted the same method to fabricate functional fibers with expected properties by controlling flow conditions. [32] Based on these studies, Zhang's group designed microfluidic chips mimicking the first-order and second-order exponential decay function of silk glands and prepared high-performance artificial silk fibers. [24][25][26]33,34] In our previous work, [35,36] statistics of spider's major ampullate (MA) gland of Nephila edulis were extracted from the work of Knight et al., [12] and then a microfluidic chip was prepared which fitted well to the second-order exponential decay function. The bioinspired chip possessed excellent similarity with the MA gland of spider, and was used to prepare RSF/cellulose nanofibers (CNF) hybrid fibers. However, there were some differences between the size of our microfluidic chip and the ampullate gland of spider. First, the actual diameter of lumen in the MA gland of N. edulis is from ≈250 to 8 µm. [12] However, high concentration of RSF/CNF suspensions (30 wt%) cannot flow through Microfluidic spinning has been used to mimic and discover the natural spinning process of silk. However, it is still challenging to understand the orientation and alignment of silk-spinning through microfluidic chips. Here, flow analysis is performed for a bioinspired microfluidic chip mimicking the shape of a spider's major ampullate gland a...

Bioinspired silk fibroin materials: From silk building blocks extraction and reconstruction to advanced biomedical applications

“…By using this natural spinneret, silk fiber with excellent comprehensive performance can be obtained at normal temperature and pressure. Biomimetic spinning by microfluidic chip refers to this structure and environment might obtain fiber materials with high performance and has become an important research topic in the construction of RSF fiber [ [58] , [59] , [60] ]. In addition, some conventional wet spinning and dry spinning methods have also been attempted to fabricate RSF fibers [ 61 , 62 ].…”

Microfluidic Nanomaterial Synthesis and In Situ SAXS, WAXS, or SANS Characterization: Manipulation of Size Characteristics and Online Elucidation of Dynamic Structural Transitions

“…In addition to the aforementioned online investigations, it is worth mentioning the growing interest in coupling SAXS (or SANS) with suitable microfluidic devices for the in situ characterization of hard solid nanoparticles, including nanocrystals, silk fibers, and millimeter-sized supercrystals [ 41 , 42 , 43 , 55 , 56 , 57 , 86 ]. For instance, Chen et al reported through in situ UV–vis, and time-resolved microfocus SAXS experiments on the formation process of monodispersed gold nanoparticles with different sizes in a stopped-flow microfluidics ( Figure 5 A) [ 86 ].…”

“…Here, 2D and 3D microfluidic platforms are attractive for real-time tracking analysis of nucleation and monitoring of growth mechanisms of hard metal nanocrystals [ 39 , 40 , 41 , 42 , 43 ], in situ (online), high-throughput protein structure screening and analysis during crystallization processes and under various conditions [ 44 , 45 ], real-time monitoring of structural dynamic events during the generation of nano-self-assemblies [ 5 , 28 , 30 , 31 , 46 , 47 ], and online self-assembly behavior of amphiphiles or macromolecules under flow conditions [ 44 , 46 , 48 , 49 , 50 , 51 ]. Further, the use is extended to other research areas, including in situ characterization studies for monitoring the dynamic structural events during the digestion of drug formulations [ 52 ], the exposure of charged nano-self assemblies to divalent ions [ 53 , 54 ], the spinning process of artificial fibers [ 55 ], the generation of single domain supercrystals [ 56 ], the precipitation of crystals in moving droplets [ 57 ], and the nanoparticle agglomeration [ 58 ].…”

Cellulose through the Lens of Microfluidics: A Review

“…This finding sets the path for further research into the demystification of the enigma of the natural spinning process. It offers a complete and methodical look at the process of creating highly oriented artificial fibres for biological applications [118]. In the development, regeneration and characterization of a blended system combining Bombyx Mori silk fibroin protein and cellulose acetate, a cellulose derivative, silk may be mixed with cellulose derivatives [119].…”

“…In the development, regeneration and characterization of a blended system combining Bombyx Mori silk fibroin protein and cellulose acetate, a cellulose derivative, silk may be mixed with cellulose derivatives [119]. Many studies on the combination of silk and cellulose acetate for filament/fibre manufacturing may be found in the literature [106,114,118,[120][121][122][123][124][125][126][127][128].…”