Rapid Synthesis of Silk-Like Polymers Facilitated by Microwave Irradiation and Click Chemistry

Abstract

Silk is a natural fiber that surpasses most man-made polymers in its combination of strength and toughness. Silk fibroin, the primary protein component of silk, can be synthetically mimicked by a linear copolymer with alternating rigid and soft segments. Strategies for chemical synthesis of such silk-like polymers have persistently resulted in poor sequence control, long reaction times, and low molecular weights. Here, we present a two-stage approach for rapidly synthesizing silk-like polymers with precisely defined rigid blocks. This approach utilizes solid-phase peptide synthesis to create uniform oligoalanine "prepolymers", followed by microwave-assisted step-growth polymerization with bifunctional poly(ethylene glycol). Multiple coupling chemistries and reaction conditions were explored, with microwave-assisted click chemistry yielding polymers with M w ∼ 14 kg/mol in less than 20 min. These polymers formed antiparallel β-sheets and nanofibers, which is consistent with the structure of natural silk fibroin. Thus, our strategy demonstrates a promising modular approach for synthesizing silk-like polymers. Article pubs.acs.org/Biomac

Concurrent Reduction and Stabilization of Graphene Oxide Dispersion by Silk-Inspired Polymer

“…FTIR for oligo(alanine)propandiamine (1) reveals a strong peak at 1626 cm −1 , which is a signature peak for the antiparallel β-sheet structure observed in the natural spider silk. 17,20,23,28 The same signal was found in the silk-inspired polymer 4 (Figure 2a), which indicates that the formation of an antiparallel β-sheet structure was unaffected during the conjugation of PEG to oligo(alanine) via a microwave-assisted DA reaction (Figure S6). In addition to that, the appearance of a less pronounced peak at 1656 cm −1 corresponds to the presence of a random-coil or helical secondary structure.…”

Genetically Engineered Viral Vectors and Organic‐Based Non‐Viral Nanocarriers for Drug Delivery Applications

“…Like chemically modified silk materials, composite materials and synthetic materials are decomposed and synthesized by enzymatic polymerization which can be a natural matrix effective for drug delivery. [51,52] Concerning genetically engineered silk-like polymers, they have been mainly restricted to those designed on the repetition of the sequences [GGAGQGGYGGLGSQ-GAGRGGLGGQGGAG] and [GPGGYGGPGQQGPGGYAPGQQPSGPGS] from the silk produced by the Nephila clavipes major ampullate glands 1 and 2, respectively. [14] Some modifications of those base sequences have also been discovered.…”

Monomer Choice Influences N-Acryloyl Amino Acid Grafter Conversion via Protease Catalysis

“…Since PCPS often results in average chain lengths (DP n-avg ) of about 5−10 residues, the conjugation to synthetic or natural polymeric chains can lead to synergistic interactions between the tethered chains that provides properties that mimic longer-chain analogues. 20 Kinetically controlled PCPS by cystine proteases (papain) is normally performed in aqueous buffer, using amino acid ethyl ester (AA-OEt) monomers, without protection−deprotection of the N-termini of the growing chain and amino acid (AA) functional R-groups (e.g., lysine, ε and α amine). 21 Generally, PCPS is conducted at a pH of about 8 and temperature 40 °C for seconds to hours with peptide yields between 30 and 80%.…”