Manufacturing 6-[18F]Fluoro-L-DOPA via Flow Chemistry-Enhanced Photoredox Radiofluorination.

In this study, we introduce a practical methodology for the synthesis of PET probes by seamlessly combining flow chemistry with photoredox radiofluorination. The clinical PET tracer 6-[18F]FDOPA was smoothly prepared in a 24.3% non-decay-corrected yield with over 99.0% radiochemical purity (RCP) and enantiomeric excess (ee), notably by a simple cartridge-based purification. The flow chemistry-enhanced photolabeling method supplies an efficient and versatile solution for the synthesis of 6-[18F]FDOPA and for more PET tracer development.

Alternative strategies for the recombinant synthesis, DOPA modification and analysis of mussel foot proteins - A case study for Mefp-3 from Mytilus edulis.

Mussel foot proteins (Mfps) possess unique binding properties to various surfaces due to the presence of L-3,4-dihydroxyphenylalanine (DOPA). Mytilus edulis foot protein-3 (Mefp-3) is one of several proteins in the byssal adhesive plaque. Its localization at the plaque-substrate interface approved that Mefp-3 plays a key role in adhesion. Therefore, the protein is suitable for the development of innovative bio-based binders. However, recombinant Mfp-3s are mainly purified from inclusion bodies under denaturing conditions. Here, we describe a robust and reproducible protocol for obtaining soluble and tag-free Mefp-3 using the SUMO-fusion technology. Additionally, a microbial tyrosinase from Verrucomicrobium spinosum was used for the in vitro hydroxylation of peptide-bound tyrosines in Mefp-3 for the first time. The highly hydroxylated Mefp-3, confirmed by MALDI-TOF-MS, exhibited excellent adhesive properties comparable to a commercial glue. These results demonstrate a concerted and simplified high yield production process for recombinant soluble and tag-free Mfp3-based proteins with on demand DOPA modification.

Self-Healable Adhesive Hydrogel with a Preserved Underwater Adhesive Ability Based on Histidine-Zinc Coordination and a Bioengineered Hybrid Mussel Protein.

Mussels are marine organisms that are capable of constructing an underwater adhesion between their bodies and rigid structures. It is well known that mussels achieve underwater adhesion through the presence of mussel adhesive proteins (MAPs) that contain high levels of 3,4-dihydroxyphenylalanine (DOPA). Although the extraordinary underwater adhesive properties of mussels are attributed to DOPA, its capacity to play a dual role in surface adhesion and internal cohesion is inherently limited. However, mussels employ a combination of chemical moieties, not just DOPA, along with anatomical components, such as plaque and byssus, in underwater adhesion. This also involves junction proteins that connect the plaque and byssus. In this study, a novel hybrid MAP was bioengineered via the fusion of the plaque protein (foot protein type 1) and the histidine-rich domain of the junction protein (foot protein type 4). To achieve direct adhesion underwater, the adhesive should maintain surface adhesion without disintegrating. Notably, the histidine-Zn-coordinated hybrid MAP hydrogel maintained a high surface adhesion ability even after cross-linking because of the preservation of its unoxidized and non-cross-linked DOPA moieties. The formulated adhesive hydrogel system based on the bioengineered hybrid MAP exhibited self-healing properties, owing to the reversible metal coordination bonds. The developed adhesive hydrogel exhibits outstanding levels of bulk adhesion in underwater environments, highlighting its potential as an effective adhesive biomaterial. Therefore, the introduction of histidine-rich domains into MAPs may be applied in various studies to formulate mussel-inspired adhesives with self-healing properties and to fully utilize the adhesive ability of DOPA.

Selectively Positioned Catechol Moiety Supports Ultrashort Self-Assembling Peptide Hydrogel Adhesion for Coral Restoration.

Coral reef survival is threatened globally. One way to restore this delicate ecosystem is to enhance coral growth by the controlled propagation of coral fragments. To be sustainable, this technique requires the use of biocompatible underwater adhesives. Hydrogels based on rationally designed ultrashort self-assembling peptides (USP) are of great interest for various biological and environmental applications, due to their biocompatibility and tunable mechanical properties. Implementing superior adhesion properties to the USP hydrogel compounds is crucial in both water and high ionic strength solutions and is relevant in medical and marine environmental applications such as coral regeneration. Some marine animals secrete large quantities of the aminoacids dopa and lysine to enhance their adhesion to wet surfaces. Therefore, the addition of catechol moieties to the USP sequence containing lysine (IIZK) should improve the adhesive properties of USP hydrogels. However, it is challenging to place the catechol moiety (Do) within the USP sequence at an optimal position without compromising the hydrogel self-assembly process and mechanical properties. Here, we demonstrate that, among three USP hydrogels, DoIIZK is the least adhesive and that the adhesiveness of the IIZDoK hydrogel is compromised by its poor mechanical properties. The best adhesion outcome was achieved using the IIZKDo hydrogel, the only one to show equally sound adhesive and mechanical properties. A mechanistic understanding of this outcome is presented here. This property was confirmed by the successful gluing of coral fragments by means of IIZKDo hydrogel that are still thriving after more than three years since the deployment. The validated biocompatibility of this underwater hydrogel glue suggests that it could be advantageously implemented for other applications, such as surgical interventions.

Mussel-Inspired Cation-π Interactions: Wet Adhesion and Biomimetic Materials.

Cation-π interaction is one of the most important noncovalent interactions identified in biosystems, which has been proven to play an essential role in the strong adhesion of marine mussels. In addition to the well-known catecholic amino acid, l-3,4-dihydroxyphenylalanine, mussel foot proteins are rich in various aromatic moieties (e.g., tyrosine, phenylalanine, and tryptophan) and cationic residues (e.g., lysine, arginine, and histidine), which favor a series of short-range cation-π interactions with adjustable strengths, serving as a prototype for the development of high-performance underwater adhesives. This work highlights our recent advances in understanding and utilizing cation-π interactions in underwater adhesives, focusing on three aspects: (1) the investigation of the cation-π interaction mechanisms in mussel foot proteins via force-measuring techniques; (2) the modulation of cation-π interactions in mussel mimetic polymers with the variation of cations, anions, and aromatic groups; (3) the design of wet adhesives based on these revealed principles, leading to functional materials in the form of films, coacervates, and hydrogels with biomedical and engineering applications. This review provides valuable insights into the development and optimization of smart materials based on cation-π interactions.

Statistical Copolymers that Mimic Aspects of Mussel Adhesive Proteins: Access to Robust Adhesive-Domains for Non-Covalent Surface PEGylation.

Reconstructing functional sequence motifs of proteins, using statistical copolymers greatly reduces the information content, but simplifies synthesis significantly. Key amino acid residues involved in the adhesion of mussel foot proteins are identified. The side-chain functionalities of Dopa, lysine, and arginine are abstracted and incorporated into acrylate monomers to allow controlled radical polymerization. The resulting Dopa-acrylate (Y*-acr), arginine-acrylate (R-acr), and lysine-acrylate (K-acr) monomers are polymerized in different monomer ratios and compositions by reversible addition fragmentation transfer polymerization with a poly(ethylene glycol) (PEG) macrochain transfer agent. This results in two sets of PEG-block-copolymers with statistical mixtures and different monomer ratios of catechol/primary amine and catechol/guanidine side-chain functionalities, both important pairs for mimicking π-cation interactions. The coating behavior of these PEG-block-copolymers is evaluated using quartz crystal microbalance with dissipation energy monitoring (QCM-D), leading to non-covalent PEGylation of the substrates with clear compositional optima in the coating stability and antifouling properties. The coatings prevent non-reversible albumin or serum adsorption, as well as reduce cellular adhesion and fungal spore attachment.

DOPA Residues Endow Collagen with Radical Scavenging Capacity.

Here we uncover collagen, the main structural protein of all connective tissues, as a redox-active material. We identify dihydroxyphenylalanine (DOPA) residues, post-translational oxidation products of tyrosine residues, to be common in collagen derived from different connective tissues. We observe that these DOPA residues endow collagen with substantial radical scavenging capacity. When reducing radicals, DOPA residues work as redox relay: they convert to the quinone and generate hydrogen peroxide. In this dual function, DOPA outcompetes its amino acid precursors and ascorbic acid. Our results establish DOPA residues as redox-active side chains of collagens, probably protecting connective tissues against radicals formed under mechanical stress and/or inflammation.

Direct and Efficient Incorporation of DOPA into Resilin-Like Proteins Enables Cross-Linking into Tunable Hydrogels.

3,4-Dihydroxyphenylalanine (DOPA), a naturally occurring yet noncanonical amino acid, endows protein polymers with diverse chemical reactivities and novel functionalities. Although many efforts have been made to incorporate DOPA into proteins, the incorporation efficiency and production titer remain low and severely hinder the exploration of these peculiar proteins for biomaterial fabrication. Here, we report an efficient biosynthetic strategy to produce large amounts of DOPA-incorporated structural proteins for the fabrication of hydrogels with tunable mechanical properties. First, synthetic genes were constructed that encode repetitive resilin-like proteins (RLPs) with varying proportions of tyrosine residues and molecular weights (Mw). Decoding of these genes into RLPs incorporated with DOPA was achieved via mis-aminoacylation of DOPA by endogenous tyrosyl-tRNA synthetase (TyrRS) in recombinant Escherichia coli cells. By developing a stoichiometry-guided two-phase culture strategy, we achieved independent control of the bacterial growth and protein synthesis phases. This enabled hyperproduction of the DOPA-incorporated RLPs at gram-per-liter levels and with a high DOPA incorporation yield of 76-85%. The purified DOPA-containing RLPs were then successfully cross-linked into bulk hydrogels via facile DOPA-Fe3+ complexations. Interestingly, these hydrogels exhibited viscoelastic and self-healing properties that are highly dependent on the catechol content and Mw of the RLPs. Finally, exploration of the molecular cross-linking mechanisms revealed that higher DOPA contents of the proteins would result in the concomitant occurrence of metal coordination and oxidative covalent cross-linking. In summary, our results suggest a useful platform to generate DOPA-functionalized protein materials and provide deeper insights into the gelation systems based on DOPA chemistry.

Ternary Synergy of Lys, Dopa, and Phe Results in Strong Cohesion of Peptide Films.

Synergistic interactions between 3,4-dihydroxyphenylalanine (Dopa, Y*), cationic residues, and the aromatic rings have been recently highlighted as influential factors that enhance the underwater adhesion strength of mussel foot proteins and their derivatives. In this study, we report the first ever evidence of a cation-catechol-benzene ternary synergy between Y*, lysine (Lys, K), and phenylalanine (Phe, F) in adhesive peptides. We synthesized three hexapeptides containing a different combination of Y*, K, and F, i.e., (KY*)3, (KF)3, and (KY*F)2, respectively, exploring the relationship between the cohesive performance and molecular architecture of peptides. The peptide with the (KY*F)2 sequence displays the strongest underwater cohesion energy of 10.3 ± 0.3 mJ m-2 from direct nanoscale surface force measurements. Combined with molecular dynamics simulation, we demonstrated that there are more bonding interactions (including cation-π, π-π, and hydrogen bond interactions) in (KY*F)2 compared to the other two peptides. In addition, peptide (KY*F)2 still shows the strongest cohesive energies of 7.6 ± 0.7 and 3.7 ± 0.5 mJ m-2 in acidic and high-ionic strength environments, respectively, although the cohesive energy decreases compared to the value in pure water. Our results further explain the underwater cohesion mechanisms combining multiple interactions and offer insights on designing Dopa containing underwater adhesives.

Bio-inspired conductive adhesive based on calcium-free alginate hydrogels for bioelectronic interfaces.

Electrode impedance is one of the greatest challenges facing neural interfacing medical devices and the use of electrical stimulation-based therapies in the fields of neurology and regenerative medicine. Maximizing contact between electronics and tissue would allow for more accurate recordings of neural activity and to stimulate with less power in implantable devices as electric signals could be more precisely transferred by a stable interfacial area. Neural environments, inherently wet and ion-rich, present a unique challenge for traditional conductive adhesives. As such, we look to marine mussels that use a 3,4-dihydroxyphenyl-L-analine (DOPA)-containing proteinaceous excretion to adhere to a variety of substrates for inspiration. By functionalizing alginate, which is an abundantly available natural polymer, with the catechol residues DOPA contains, we developed a hydrogel-based matrix to which carbon-based nanofiller was added to render it conductive. The synthesized product had adhesive energy within the range of previously reported mussel-based polymers, good electrical properties and was not cytotoxic to brain derived neural precursor cells.

Mussels Fabricate Porous Glues via Multiphase Liquid-Liquid Phase Separation of Multiprotein Condensates.

Mussels (Mytilus edulis) adhere to hard surfaces in intertidal marine habitats with a porous underwater glue called the byssus plaque. The plaque is an established role model for bioinspired underwater glues and comprises at least six proteins, most of which are highly cationic and enriched in the post-translationally modified amino acid 3,4-dihydroxyphenylalanine (DOPA). While much is known about the chemistry of plaque adhesion, less is understood about the natural plaque formation process. Here, we investigated plaque structure and formation using 3D electron microscopic imaging, revealing that micro- and nanopores form spontaneously during secretion of protein-filled secretory vesicles. To better understand this process, we developed a method to purify intact secretory vesicles for in vitro assembly studies. We discovered that each vesicle contains a sulfate-associated fluid condensate consisting of ∼9 histidine- and/or DOPA-rich proteins, which are presumably the required ingredients for building a plaque. Rupturing vesicles under specific buffering conditions relevant for natural assembly led to controlled multiphase liquid-liquid phase separation (LLPS) of different proteins, resulting in formation of a continuous phase with coexisting droplets. Rapid coarsening of the droplet phase was arrested through pH-dependent cross-linking of the continuous phase, producing native-like solid porous "microplaques" with droplet proteins remaining as fluid condensates within the pores. Results indicate that histidine deprotonation and sulfates figure prominently in condensate cross-linking. Distilled concepts suggest that combining phase separation with tunable cross-linking kinetics could be effective for microfabricating hierarchically porous materials via self-assembly.

Design, synthesis, and characterization of a novel dual cross-linked gelatin-based bioadhesive for hard and soft tissues adhesion capability.

Many surgical treatments require a suitable tissue adhesive that maintains its performance in wet conditions and can be applied simultaneously for hard and soft tissues. In the present study, a dual cross-linked tissue adhesive was synthesized by mixing the gelatin methacryloyl (Gel-MA) and gelatin-dopamine conjugate (Gel-Dopa). The setting reaction was based on a photopolymerization process in the presence of a combination of riboflavin and triethanolamine and a chemical cross-linking process attributed to the genipin as a natural cross-linker. Modified gelatin macromolecules were characterized and the best wavelength for free radical generation in the presence of riboflavin was obtained. Tissue adhesives were prepared with 30% hydrogels of Gel-MA and Gel-Dopa with different ratios in distilled water. The gelation occurred in a short time after light irradiation. The chemical, mechanical, physical, and cytotoxicity properties of the tissue adhesives were evaluated. The results showed that despite photopolymerization, chemical crosslinking with genipin played a more critical role in the setting process. Water uptake, degradation behavior, cytotoxicity, and adhesion properties of the adhesives were correlated with the ratio of the components. The SEM images showed a porous structure that could ensure the entry of cells and nutrients into the surgical area. While acceptable properties in most experiments were observed, all features were improved as the Gel-Dopa ratio increased. Also, the obtained hydrogels revealed excellent adhesive properties, particularly with bone even after wet incubation, and it was attributed to the amount of gelatin-dopamine conjugate. From the obtained results, it was concluded that a dual adhesive hydrogel based on gelatin macromolecules could be a good candidate as a tissue adhesive in wet condition.

A highly stretchable, UV resistant and underwater adhesive hydrogel based on xylan derivative for sensing.

Hydrogels with fascinating adhesion have been demonstrated great potential in various applications. However, most hydrogels lose their adhesion in wet or underwater environments due to the influence of interfacial water. Inspired by mussel, an underwater adhesive hydrogel was facilely fabricated by introducing electrostatic interactions, which consisted of poly (acrylic acid) (PAA), quaternized xylan (QAX) and tannic acid (TA). In this hydrogel, -COO- from PAA, -N+(CH3)3 from QAX and catechol group from TA resembled amino acids with negative and positive charges and 3,4-dihydroxyphenylalanine units in mussel, which endowed the hydrogels with great underwater adhesion through multiple interactions. Notably, acrylic acid (AA) played a key role in the dispersion of the system. QAX, a biomass derived from plants with excellent properties, worked with PAA to construct hydrogel networks. The resultant hydrogels exhibited excellent mechanical properties including remarkable stretchability (>4000 %) and compressibility. Moreover, the hydrogels had superior UV-blocking (~99.96 %), and showed good adhesion both in air and underwater. The hydrogels can be exploited as a wearable sensor to monitor human motions and even subtle motions, which have the potential to be explored in human health monitoring.

Metal-ligand complexation and clustering in mussel-inspired side-chain functionalized supramolecular hydrogels.

Byssus threads of mussels have high resistance against abrasion in wave-swept habitats because of their outer cuticle, which is rich in amino acid dopa complexes with Fe3+ ions. This stems from the transient nature of metal-ligand complexes that creates extra relaxation mechanisms. Inspired by this concept, in this work, supramolecular hydrogels based on poly(acrylic acid) functionalized with nitrocatechol groups are synthesized. Polymer chains are physically crosslinked via nitrocatechol-Fe3+ complexes. The hydrogels have different polymer volume fractions as well as different nitrocatechol : Fe3+ molar ratios. The strength of the supramolecular crosslinks strongly depends on the pH of the medium. The dynamics of these hydrogels are studied by stress relaxation experiments followed by calculation of the relaxation time spectrum. Generally, samples have three relaxation modes, including dissociation of distinct metal-ligand complexes, reptation of sticky polymer chains, and disengagement of network segments from supramolecular aggregates and clusters. Such clusters hinder the terminal relaxation and potentially increase the stability of supramolecular hydrogels.

Mussel-inspired polyurethane coating for bio-surface functionalization to enhance substrate adhesion and cell biocompatibility.

Considerable implant materials are prone to cause a severe inflammatory reaction due to poor histocompatibility, which leads to various complications and implant failure. Surface coating modification of these implant materials is one of the most important techniques to settle this problem. However, fabricating a coating with both adequate adhesiveness and excellent biocompatibility remains a challenge. Inspired by the adhesion mechanism of mussels, a series of mussel-inspired polyurethanes (PU-LDAs) were synthysized through a step growth polymerization based on hexamethylene diisocyanate as a hard segment, polytetra-methylene-ether-glycol as a soft segment, lysine-dopamine (LDA) and butanediol as chain extenders with different mole ratios.The coatings of PU-LDAs were applied to various substrates, such as stainless steel, glass and PP using a facile one-step coating process. The introduction of 3,4-dihydroxyphenylalanine (DOPA) groups can greatly improve the adhesion ability of the coatings to the substrates demonstrated by a 180° peel test. The peel strength of the PU-LDA100 coating containing high LDA content was 76.3, 48.5 and 67.5 N/m, which was 106.2%, 246.4% and 192.2% higher than that of the PU-LDA00 coating without LDA on the surface of stainless steel, glass and PP, respectively. Meanwhile, this PU coating has a lower immune inflammatory response which provides a universal method for surface modification of implant materials. Moreover, the DOPA groups in PU-LDAs could combine with the amino and thiol groups on cell membrane surface, leading to the improvement of cell adhesion and growth. Therefore, it has great potential application in the field of biomedical implant materials for the clinic.

Injectable pH-responsive adhesive hydrogels for bone tissue engineering inspired by the underwater attachment strategy of marine mussels.

A major challenge in tissue engineering is the development of alternatives to traditional bone autografts and allografts that can regenerate critical-sized bone defects. Here we present the design of injectable pH-responsive double-crosslinked adhesive hydrogels inspired by the molecular mechanism and environmental post-processing of marine mussel adhesive. Nine adhesive hydrogel formulations were developed through the conjugation of crosslinkable catechol functional groups (DOPA) and the synthetic oligomer oligo[poly(ethylene glycol) fumarate] (OPF), varying the DOPA content (w/w%) and molecular weight (MW) of the OPF backbone to produce formulations with a range of swelling ratios, porosities, and crosslink densities. DOPA incorporation altered the surface chemistry, mechanical properties, and surface topography of hydrogels, resulting in an increase in material stiffness, slower degradation, and enhanced pre-osteoblast cell attachment and proliferation. When injected within simulated bone defects, DOPA-mediated interfacial adhesive interactions also prevented the displacement of scaffolds, an effect that was maintained even after swelling within physiological conditions. Taken together, OPF-DOPA hydrogels represent a promising new material to enhanced tissue integration and the prevention of the post-implantation migration of scaffolds that can occur due to biomechanical loading in vivo.

Thiol-Rich fp-6 Controls the Tautomer Equilibrium of Oxidized Dopa in Interfacial Mussel Foot Proteins.

3,4-Dihydroxyphenylalanine (Dopa) is a versatile molecule that enables marine mussels to achieve successful underwater adhesion. However, due to its complicated redox chemistry and vulnerability to oxidation, controlling surface adhesion and cohesion has been a challenging issue to overcome. Foot protein type 6 (fp-6), a thiol-rich interfacial mussel adhesive protein, has been reported as a proteinaceous antioxidant for mussels that helps Dopa maintain surface adhesion ability. In this study, we focused on the role of fp-6 in oxidized Dopa. The effect on the tautomer equilibrium of oxidized Dopa was investigated using recombinant fp-6 (rfp-6) and Dopa-incorporated foot protein type 3 fast variant (drfp-3F), which were produced in bacterial cells. The redox chemistry of Dopa in drfp-3F and the role of rfp-6 were observed using a UV-vis spectrophotometer and a surface forces apparatus (SFA). We discovered that rfp-6 shifts the tautomer equilibrium to ΔDopa as a preferred tautomer for oxidized Dopa in drfp-3F and makes drfp-3F better on underwater surface adhesion.

Effect of Cross-Linkers on Mussel- and Elastin-Inspired Adhesives on Physiological Substrates.

Surgical adhesives can be useful in wound closure because they reduce the risk of infection and pain associated with sutures and staples. However, there are no commercially available surgical adhesives for soft tissue wound closure. To be effective, soft tissue adhesives must be soft and flexible, strongly cohesive and adhesive, biocompatible, and effective in a moist environment. To address these criteria, we draw inspiration from the elasticity and resilience of elastin proteins and the adhesive of marine mussels. We used an elastin-like polypeptide (ELP) for the backbone of our adhesive material due to its elasticity and biocompatibility. A mussel-inspired adhesive molecule, l-3,4-dihydroxyphenylalanine (DOPA), was incorporated into the adhesive to confer wet-setting adhesion. In this study, an ELP named YKV was designed to include tyrosine residues and lysine residues, which contain amine groups. A modified version of YKV, named mYKV, was created through enzymatic conversion of tyrosine residues into DOPA. The ELPs were combined with iron(III) nitrate, sodium periodate, and/or tris(hydroxymethyl)phosphine (THP) cross-linkers to investigate the effect of DOPA- and amine-based cross-linking on adhesion strength and cure time on porcine skin in a warm, humid environment. Incorporation of DOPA into the ELP increased adhesive strength by 2.5 times and reduced failure rates. Iron cross-linkers improved adhesion in the presence of DOPA. THP increased adhesion for all proteins tested even in the absence of DOPA. Using multiple cross-linkers in a single formulation did not significantly improve adhesion. The adhesives with the highest performance (iron nitrate mixed with mYKV and THP mixed with YKV or mYKV) on porcine skin had 10-18 times higher adhesion than a commercial sealant and reached appreciable adhesive strength within 10 min.

Genetically encoded dihydroxyphenylalanine coupled with tyrosinase for strain promoted labeling.

Protein modifications through genetic code engineering have a remarkable impact on macromolecule engineering, protein translocation, protein-protein interaction, and cell biology. We used the newly developed molecular biology approach, genetic code engineering, for fine-tuning of proteins for biological availability. Here, we have introduced 3, 4-dihydroxy-l-phenylalanine in recombinant proteins by selective pressure incorporation method for protein-based cell labeling applications. The congener proteins treated with tyrosinase convert 3, 4-dihydroxy-l-phenylalanine to dopaquinone for strain-promoted click chemistry. Initially, the single-step Strain-Promoted Oxidation-Controlled Cyclooctyne-1,2-quinone Cycloaddition was studied using tyrosinase catalyzed congener protein and optimized the temporally controlled conjugation with (1R,8S,9s)-Bicyclo[6.1.0]non-4-yn-9-ylmethanol. Then, the feasibility of tyrosinase-treated congener annexin A5 with easily reactive quinone functional moiety was conjugated with fluorescent tag dibenzocyclooctyne-PEG4-TAMRA for labeling of apoptotic cells. Thus, the congener proteins-based products demonstrate selective cell labeling and apoptosis detection in EA.hy926 cells even after the protein modifications. Hence, genetic code engineering can be coupled with click chemistry to develop various protein-based fluorescent labels.

Antiviral Activity of Peptide-Based Assemblies.

The COVID-19 pandemic highlighted the importance of developing surfaces and coatings with antiviral activity. Here, we present, for the first time, peptide-based assemblies that can kill viruses. The minimal inhibitory concentration (MIC) of the assemblies is in the range tens of micrograms per milliliter. This value is 2 orders of magnitude smaller than the MIC of metal nanoparticles. When applied on a surface, by drop casting, the peptide spherical assemblies adhere to the surface and form an antiviral coating against both RNA- and DNA-based viruses including coronavirus. Our results show that the coating reduced the number of T4 bacteriophages (DNA-based virus) by 3 log, compared with an untreated surface and 6 log, when compared with a stock solution. Importantly, we showed that this coating completely inactivated canine coronavirus (RNA-based virus). This peptide-based coating can be useful wherever sterile surfaces are needed to reduce the risk of viral transmission.