Sugar Functionalization of Silks with Pathway‐Controlled Substitution and Properties

Abstract

Silk biomaterials are important for applications in biomedical fields due to their outstanding mechanical properties, biocompatibility, and tunable biodegradation. Chemical functionalization of silk by various chemistries can be leveraged to enhance and tune these features and enable the expansion of silk‐based biomaterials into additional fields. Sugars are particularly relevant for intracellular communication, signal transduction events, as well as in hydrated extracellular matrices such as in cartilage, vitreous, and brain tissues. Multiple reaction pathways are demonstrated (carboxylation of serines followed by carbodiimide coupling with glucosamine, carboxylation of tyrosines followed by carbodiimide coupling with glucosamine; direct carbodiimide coupling of the inherent carboxylic acids of silk (aspartic and glutamic acid) with glucosamine) for the covalent conjugation of glucosamine onto silk with characterization by proton nuclear magnetic resonance (1H‐NMR), liquid chromatography tandem mass spectroscopy (LC‐MS), water contact angle (WCA), and Fourier transform infrared (FTIR) spectroscopy. The results indicate that different pathways substitute different amounts of glucosamine onto silk chains, with control over resulting material properties, including hydrophobicity/hydrophilicity and biological responses. The aqueous processability of these conjugates into functional material formats (films, sponges) is assessed. These new classes of bio‐inspired materials can lead to multifunctional biomaterials for potential applications in different fields of biomedical engineering.

Boronic Acid-Tethered Silk Fibroin for pH-Dependent Mucoadhesion

“…However, diazonium reactions can cause aggregation due to the reaction conditions . In this case, the use of acetic acid as a solvent (due to the limited solubility of 3-amino phenyl boronic acid in common diazonium coupling conditions , ) increased the formation of aggregates which limited the number of boronic acid groups available for coupling with diols. Lithium bromide has been widely used to dissolve silk since the protein does not aggregate and shows high stability after dissolution. , Therefore, after synthesis, the solution was lyophilized and treated with a 9.3 M solution of lithium bromide at 60 °C for 1 h to break down the aggregates.…”

Horseradish Peroxidase Catalyzed Silk–Prefoldin Composite Hydrogel Networks

“…Extraction of silk fibroin (SF) aqueous solutions was performed using our previously reported procedure . Briefly, 5 g of cut cocoons were boiled in 2 L of 0.02 M Na 2 CO 3 (Sigma-Aldrich, St. Louis, MO) for 60 min.…”

“…The purified silk solutions were centrifuged twice at 9000 rpm for 20 min at 4 °C for further purification. The silk solution was collected, and the concentration was determined as reported previously . The solution was stored at 4 °C before further use.…”

A brief review on the mechanisms and approaches of silk spinning-inspired biofabrication

“…The hydroxyl group makes tyrosine more polar than phenylalanine, which enables hydrogen bonding and improves the solubility in water; the aromatic ring primarily renders tyrosine hydrophobic and enables hydrophobic interactions. Also, the redox capability of tyrosine has been exploited to process silk proteins, including chemical modification ( Sahoo et al, 2021 ; Liu et al, 2022 ), hydrogel crosslinking ( Applegate et al, 2016 ; McGill et al, 2017 ; Choi et al, 2021 ; Mu et al, 2022b ), and three-dimensional (3D) printing ( Costa et al, 2017 ; Mu et al, 2020b ).…”