Iridescent biofilms of Cellulophaga lytica are tunable platforms for scalable, ordered materials.

Nature offers many examples of materials which exhibit exceptional properties due to hierarchical assembly of their constituents. In well-studied multi-cellular systems, such as the morpho butterfly, a visible indication of having ordered submicron features is given by the display of structural color. Detailed investigations of nature's designs have yielded mechanistic insights and led to the development of biomimetic materials at laboratory scales. However, the manufacturing of hierarchical assemblies at industrial scales remains difficult. Biomanufacturing aims to leverage the autonomy of biological systems to produce materials at lower cost and with fewer carbon emissions. Earlier reports documented that some bacteria, particularly those with gliding motility, self-assemble into biofilms with polycrystalline structures and exhibit glittery, iridescent colors. The current study demonstrates the potential of using one of these bacteria, Cellulophaga lytica, as a platform for the large scale biomanufacturing of ordered materials. Specific approaches for controlling C. lytica biofilm optical, spatial and temporal properties are reported. Complementary microscopy-based studies reveal that biofilm color variations are attributed to changes in morphology induced by cellular responses to the local environment. Incorporation of C. lytica biofilms into materials is also demonstrated, thereby facilitating their handling and downstream processing, as would be needed during manufacturing processes. Finally, the utility of C. lytica as a self-printing, photonic ink is established by this study. In summary, autonomous surface assembly of C. lytica under ambient conditions and across multiple length scales circumvent challenges that currently hinder production of ordered materials in industrial settings.

MILLER Banding Procedure for Treatment of Dialysis Access-Related Steal Syndrome, Pulmonary Hypertension, and Heart Failure.

A Minimally Invasive Limited Ligation Endoluminal-assisted Revision (MILLER) banding procedure has been used for treating patients with dialysis access-related steal syndrome (DASS) and high-flow vascular access-related pulmonary hypertension (PHT) and heart failure (HF).We performed a retrospective analysis of patients undergoing the MILLER procedure performed for DASS, HF, and PHT from our Vascular Access Database from September 2017 to October 2019. Outcomes included primary patency of banding, primary assisted patency, and secondary patency, using time-to-event analyses with Kaplan-Meier curves and life tables to estimate 6- and 12-month rates.A total of 13 patients (6 men and 7 women, mean age 60 ± 14 years) underwent the MILLER procedure, 6 patients for DASS and 7 patients for pulmonary hypertension and heart failure (PHT/HF). Technical success was achieved in all patients. The longest duration of follow-up was 28 months (median 12 months [IQR 7, 19]). One patient died at 1 month after the intervention due to stroke. One patient developed access thrombosis of the graft 3 days after the procedure. Repeat banding was required in 1 patient 8 months after the first procedure. The 6-month primary patency rate of banding following this procedure was 83% while the 12-month rate was 66%. The 6- and 12-month secondary patency rates were 87% and 75%, respectively.The MILLER procedure can be performed for DASS and PHT/HF with improvement of symptoms and good long-term patency rates. Additional interventions to maintain patency and efficacy are required on long-term follow-up.

Molecular dynamics simulations explore effects of electric field orientations on spike proteins of SARS-CoV-2 virions.

Emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its current worldwide spread have caused a pandemic of acute respiratory disease COVID-19. The virus can result in mild to severe, and even to fatal respiratory illness in humans, threatening human health and public safety. The spike (S) protein on the surface of viral membrane is responsible for viral entry into host cells. The discovery of methods to inactivate the entry of SARS-CoV-2 through disruption of the S protein binding to its cognate receptor on the host cell is an active research area. To explore other prevention strategies against the quick spread of the virus and its mutants, non-equilibrium molecular dynamics simulations have been employed to explore the possibility of manipulating the structure-activity of the SARS-CoV-2 spike glycoprotein by applying electric fields (EFs) in both the protein axial directions and in the direction perpendicular to the protein axis. We have found out the application of EFs perpendicular to the protein axis is most effective in denaturing the HR2 domain which plays critical role in viral-host membrane fusion. This finding suggests that varying irradiation angles may be an important consideration in developing EF based non-invasive technologies to inactivate the virus.

Marine Structural Protein Stability Induced by Hofmeister Salt Annealing and Enzymatic Cross-Linking.

The Humboldt squid is one of the fiercest marine predators thanks in part to its sucker ring teeth that are biopolymer blends of a protein isoform family called suckerin with compression strength that rivals silkworm silk. Here, we focus on the popular suckerin-12 isoform to understand what makes the secondary structure of this biopolymer different in water and the potential role of diverse physical and chemical cross-linkings. By choosing a salt post-treatment, in accordance with the Hofmeister series, we achieved film stability with salt annealing that is comparable to chemical cross-links. By correlating the film morphology with the protein secondary structure changes, suckerin-12 films were shown to contract upon treatment with kosmotropic salts and exhibited increased stability in water. These changes are related to the rearrangement of suckerin-12 secondary structure from random coils and helices to ß-sheets. Overall, understanding secondary structure changes caused by aqueous and ionic environments can be instructive for the tuning of the suckerin film sclerotization, its conversion to a tough biological material, and to ultimately produce the natural squid sucker ring teeth.

Characterizing and Controlling Nanoscale Self-Assembly of Suckerin-12.

Structural proteins such as "suckerins" present promising avenues for fabricating functional materials. Suckerins are a family of naturally occurring block copolymer-type proteins that comprise the sucker ring teeth of cephalopods and are known to self-assemble into supramolecular networks of nanoconfined ß-sheets. Here, we report the characterization and controllable, nanoscale self-assembly of suckerin-12 (S12). We characterize the impacts of salt, pH, and protein concentration on S12 solubility, secondary structure, and self-assembly. In doing so, we identify conditions for fabricating ∼100 nm nanoassemblies (NAs) with narrow size distributions. Finally, by installing a noncanonical amino acid (ncAA) into S12, we demonstrate the assembly of NAs that are covalently conjugated with a hydrophobic fluorophore and the ability to change self-assembly and ß-sheet content by PEGylation. This work presents new insights into the biochemistry of suckerin-12 and demonstrates how ncAAs can be used to expedite and fine-tune the design of protein materials.

Gamma estimator of Jarzynski equality for recovering binding energies from noisy dynamic data sets.

A fundamental problem in thermodynamics is the recovery of macroscopic equilibrated interaction energies from experimentally measured single-molecular interactions. The Jarzynski equality forms a theoretical basis in recovering the free energy difference between two states from exponentially averaged work performed to switch the states. In practice, the exponentially averaged work value is estimated as the mean of finite samples. Numerical simulations have shown that samples having thousands of measurements are not large enough for the mean to converge when the fluctuation of external work is above 4 kBT, which is easily observable in biomolecular interactions. We report the first example of a statistical gamma work distribution applied to single molecule pulling experiments. The Gibbs free energy of surface adsorption can be accurately evaluated even for a small sample size. The values obtained are comparable to those derived from multi-parametric surface plasmon resonance measurements and molecular dynamics simulations.

Stability of Surgical Rib Fixation Hardware after Repeat Chest Trauma.

Surgical management of rib fractures has long been a controversial topic, but improvements in rib plating technology have led to a recent increase in interest among surgeons. Unfortunately, follow-up data are limited in patients following rib fracture plating. We present a unique case of an adult male who had multiple ribs plated for symptomatic rib fracture nonunions and developed periprosthetic fractures following repeat trauma several months later. A 57-year-old male with a history of trauma was treated for symptomatic nonunion of several left lateral ribs with surgical rib fixation. He tolerated the procedure well and had significant improvement in his symptoms on follow-up. Several months later, he was hit by a motor vehicle while riding his bicycle. He was found to have flail chest with lateral segmental rib fractures of the first through second ribs, posterior periprosthetic fractures of the seventh through tenth ribs, and lateral fractures of the eleventh and twelfth ribs. The rib plating hardware was completely intact, except for a single displaced seventh rib screw. To our knowledge, this is the first case report of repeat chest trauma following rib plating. Interestingly, the patient developed posterior periprosthetic fractures, and hardware was completely intact except for a single screw that was displaced. The goal of this report is to describe the unique fracture pattern of a flail chest with prior rib plating and to describe potential revision plating techniques and complications that surgeons may encounter in the management of trauma patients with prior rib plating.

Chiral Restructuring of Peptide Enantiomers on Gold Nanomaterials.

The use of biomolecules has been invaluable at generating and controlling optical chirality in nanomaterials; however, the structure and properties of the chiral biotemplate are not well understood due to the complexity of peptide-nanoparticle interactions. In this study, we show that the complex interactions between d-peptides and gold nanomaterials led to a chiral restructuring of peptides as demonstrated by circular dichroism and proteolytic cleavage of d-peptides via gold-mediated inversion of peptide chirality. The gold nanoparticles synthesized using d-peptide produce a highly ordered atomic surface and restructured peptide bonds for enzyme cleavage. Differences in gold nanoparticle catalyzed reduction of 4-nitrophenol were observed on the basis of the chiral peptide used in nanoparticle synthesis. Notably, the proteolytic cleavage of d-peptides on gold provides an opportunity for designing nanoparticle based therapeutics to treat peptide venoms, access new chemistries, or modulate the catalytic activity of nanomaterials.

Anion-Mediated Effects on the Size and Mechanical Properties of Enzymatically Crosslinked Suckerin Hydrogels.

The suckerin family of proteins, identified from the squid sucker ring teeth assembly, offers unique mechanical properties and potential advantages over other natural biomaterials. In this study, a small suckerin isoform, suckerin-12, is used to create enzymatically crosslinked, macro-scale hydrogels. Upon exposure to specific salt conditions, suckerin-12 hydrogels contracted into a condensed state where mechanical properties are found to be modulated by the salt anion present. The rate of contraction is found to correlate well with the kosmotropic arm of the Hofmeister anion series. However, the observed changes in hydrogel mechanical properties are better explained by the ability of the salt to neutralize charges in suckerin-12 by deprotonization or charge screening. Thus, by altering the anions in the condensing salt solution, it is possible to tune the mechanical properties of suckerin-12 hydrogels. The potential for suckerins to add new properties to materials based on naturally-derived proteins is highlighted.

Disulfide Crosslinked Hydrogels Made From the Hydra Stinging Cell Protein, Minicollagen-1.

Minicollagens from cnidarian nematocysts are attractive potential building blocks for the creation of strong, lightweight and tough polymeric materials with the potential for dynamic and reconfigurable crosslinking to modulate functionality. In this study, the Hydra magnipapillata minicollagen-1 isoform was recombinantly expressed in bacteria, and a high throughput purification protocol was developed to generate milligram levels of pure protein without column chromatography. The resulting minicollagen-1 preparation demonstrated spectral properties similar to those observed with collagen and polyproline sequences as well as the ability to self-assemble into oriented fibers and bundles. Photo-crosslinking with Ru(II) ( bpy ) 3 2 + was used to create robust hydrogels that were analyzed by mechanical testing. Interestingly, the minicollagen-1 hydrogels could be dissolved with reducing agents, indicating that ruthenium-mediated photo-crosslinking was able to induce disulfide metathesis to create the hydrogels. Together, this work is an important first step in creating minicollagen-based materials whose properties can be manipulated through static and reconfigurable post-translational modifications.

Competition-Enhanced Ligand Selection to Identify DNA Aptamers.

Competition-enhanced ligand screening (CompELS) was employed to rapidly screen through large DNA libraries to identify single-stranded, oligonucleotide-based ligands called aptamers that bind to a nonbiological target. This previously unreported aptamer screening approach involves the repeated introduction of unenriched random sequence populations during the biopanning process, but avoids iterative elution and polymerase chain reaction (PCR) amplification steps inherent to traditional SELEX (systematic evolution of ligands by exponential enrichment) screening. In this study, 25 aptamers were identified against a gold surface via CompELS and evaluated to identify patterns in primary structures and predicted secondary structures. Following a final one-round competition experiment with the 25 identified aptamers, one particular aptamer sequence (1N) emerged as the most competitive adsorbate species for the gold substrate. Binding analysis indicated at least an order of magnitude difference in the binding affinity of 1N ( Kd = 5.6 × 10-10 M) compared to five other high affinity aptamer candidates ( Kd = 10-8-10-9 M) from identical secondary structure families. Collectively, these studies introduce a rapid, reliable screening and ranking platform along with a classification scheme well-suited for identifying and characterizing aptamers for nonbiological as well as biological targets.

Programmable Mechanical Properties from a Worm Jaw-Derived Biopolymer through Hierarchical Ion Exposure.

Mechanisms of biomaterial sclerotization in natural systems promise new insights into how the mechanical properties of engineered materials may be dynamically modulated. One such example involves the proteinaceous jaw of the marine sandworm, Nereis virens. Previously, the mechanical properties of the N. virens jaw were shown to be modulated by Zn binding, a property that was proposed to be enabled by the presence of the histidine-rich jaw protein, Nvjp-1. Here we demonstrate the creation of Nvjp-1-based hydrogels and show that progressive sclerotization of these hydrogels can be accomplished with hierarchical exposure to metal cations and anions. Divalent Zn cations are capable of reversibly sclerotizing the hydrogels through the formation of coordinate cross-links, an effect that is shown to be remarkably specific for Zn. Additionally, the degree of Zn-induced sclerotization is strongly influenced by the identity of the anion present in the hydrogel. Thus, the viscoelastic properties of Nvjp-1 hydrogels can be modulated through programmed, hierarchical exposure to specific cations and anions present in the sclerotizing salts. These observations have resulted in new hydrogel capabilities, such as the creation of anion-controlled shape-memory polymers, and will add to the number of control parameters that can be used to tune the properties of functional hydrogels in a dynamic manner.

Random heteropolymers preserve protein function in foreign environments.

The successful incorporation of active proteins into synthetic polymers could lead to a new class of materials with functions found only in living systems. However, proteins rarely function under the conditions suitable for polymer processing. On the basis of an analysis of trends in protein sequences and characteristic chemical patterns on protein surfaces, we designed four-monomer random heteropolymers to mimic intrinsically disordered proteins for protein solubilization and stabilization in non-native environments. The heteropolymers, with optimized composition and statistical monomer distribution, enable cell-free synthesis of membrane proteins with proper protein folding for transport and enzyme-containing plastics for toxin bioremediation. Controlling the statistical monomer distribution in a heteropolymer, rather than the specific monomer sequence, affords a new strategy to interface with biological systems for protein-based biomaterials.

Creation of energetic biothermite inks using ferritin liquid protein.

Energetic liquids function mainly as fuels due to low energy densities and slow combustion kinetics. Consequently, these properties can be significantly increased through the addition of metal nanomaterials such as aluminium. Unfortunately, nanoparticle additives are restricted to low mass fractions in liquids because of increased viscosities and severe particle agglomeration. Nanoscale protein ionic liquids represent multifunctional solvent systems that are well suited to overcoming low mass fractions of nanoparticles, producing stable nanoparticle dispersions and simultaneously offering a source of oxidizing agents for combustion of reactive nanomaterials. Here, we use iron oxide-loaded ferritin proteins to create a stable and highly energetic liquid composed of aluminium nanoparticles and ferritin proteins for printing and forming 3D shapes and structures. In total, this bioenergetic liquid exhibits increased energy output and performance, enhanced dispersion and oxidation stability, lower activation temperatures, and greater processability and functionality.

Ion Effect and Metal-Coordinated Cross-Linking for Multiscale Design of Nereis Jaw Inspired Mechanomutable Materials.

The Nvjp-1 protein is a key component in the jaws of Nereis virens, a species of marine worm. It contains over 25 mol % of histidine, which is believed to play a key role in the metal-coordinated cross-linking responsible for the structural stability and exceptional mechanical performance of the worm jaw. Understanding the nanoscale mechanism behind this cross-linking and its pathway in affecting the macroscopic mechanical behavior of the material is crucial to develop bioinspired mechanomutable materials based on Nvjp-1. Here, we use a combination of multiscale modeling and experimental synthesis to understand the behavior of this heterologous-expressed protein from the nano- to the macroscale. We have built a bottom-up molecular-based model, which includes electronic-based density functional theory calculations, atomistic simulation of the nanoscale properties with replica exchange molecular dynamics, and an elastic network model for describing the macroscale behavior at different pHs. This multiscale modeling supports the experimental synthesis of a photo-cross-linked Nvjp-1 hydrogel by proving both the nanoscale mechanisms and mechanical behavior predictions. Our theoretical results agree well with the experimental observations, showing that Nvjp-1 forms a more compact structure in the presence of Zn2+ ions with a suitable pH environment, leading to the formation of more stable intramolecular metal-coordinated cross-links. These metal-coordinated cross-links induce nanoscale aggregation of Nvjp-1, which is responsible for the hydrogel contraction observed in experiments and predicted by the model.

3D Printing of Regenerated Silk Fibroin and Antibody-Containing Microstructures via Multiphoton Lithography.

Regenerated silk fibroin, a biopolymer derived from silkworm cocoons, is a versatile material that has been widely explored for a number of applications (e.g., drug delivery, tissue repair, biocompatible electronics substrates, and optics) due to its attractive biochemical properties and processability. Here, we report on the free-form printing of silk-based, 3D microstructures through multiphoton lithography. Utilizing multiphoton lithography in conjunction with specific photoinitiator chemistry and postprint cross-linking, a number of microarchitectures were achieved including self-supporting fibroin arches. Further, the straightforward production of high fidelity and biofunctional protein architectures was enabled through the printing of aqueous fibroin/immunoglobulin solutions.

S6K is a morphogenic protein with a mechanism involving Filamin-A phosphorylation and phosphatidic acid binding.

Change of cell shape in vivo plays many roles that are central to life itself, such as embryonic development, inflammation, wound healing, and pathologic processes such as cancer metastasis. Nonetheless, the spatiotemporal mechanisms that control the concerted regulation of cell shape remain understudied. Here, we show that ribosomal S6K, which is normally considered a protein involved in protein translation, is a morphogenic protein. Its presence in cells alters the overall organization of the cell surface and cell circularity [(4π × area)/(perimeter)(2)] from 0.47 ± 0.06 units in mock-treated cells to 0.09 ± 0.03 units in S6K-overexpressing macrophages causing stellation and arborization of cell shape. This effect was partially reversed in cells expressing a kinase-inactive S6K mutant and was fully reversed in cells silenced with small interference RNA. Equally important is that S6K is itself regulated by phospholipids, specifically phosphatidic acid, whereby 300 nM 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA), but not the control 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), binds directly to S6K and causes an ∼ 2.9-fold increase in S6K catalytic activity. This was followed by an increase in Filamin A (FLNA) functionality as measured by phospho-FLNA (S(2152)) expression and by a subsequent elevation of actin nucleation. This reliance of S6K on phosphatidic acid (PA), a curvature-inducing phospholipid, explained the extra-large perimeter of cells that overexpressed S6K. Furthermore, the diversity of the response to S6K in several unrelated cell types (fibroblasts, leukocytes, and invasive cancer cells) that we report here indicates the existence of an underlying common mechanism in mammalian cells. This new signaling set, PA-S6K-FLNA-actin, sheds light for the first time into the morphogenic pathway of cytoskeletal structures that are crucial for adhesion and cell locomotion during inflammation and metastasis.

Biological versus electronic adaptive coloration: how can one inform the other?

Adaptive reflective surfaces have been a challenge for both electronic paper (e-paper) and biological organisms. Multiple colours, contrast, polarization, reflectance, diffusivity and texture must all be controlled simultaneously without optical losses in order to fully replicate the appearance of natural surfaces and vividly communicate information. This review merges the frontiers of knowledge for both biological adaptive coloration, with a focus on cephalopods, and synthetic reflective e-paper within a consistent framework of scientific metrics. Currently, the highest performance approach for both nature and technology uses colourant transposition. Three outcomes are envisioned from this review: reflective display engineers may gain new insights from millions of years of natural selection and evolution; biologists will benefit from understanding the types of mechanisms, characterization and metrics used in synthetic reflective e-paper; all scientists will gain a clearer picture of the long-term prospects for capabilities such as adaptive concealment and signaling.

Stabilization of organophosphorus hydrolase by entrapment in silk fibroin: formation of a robust enzymatic material suitable for surface coatings.

Organophosphates are some of the most acutely toxic compounds synthesized on an industrial scale, and organophosphorus hydrolase (OPH) has the ability to hydrolyze and inactivate a number of these chemicals. However, OPH activity is vulnerable to harsh environmental conditions that would accompany its practical utility in the field; a limitation that can also be extended to conditions required for incorporation of OPH into useful materials. Here we present evidence that entrapment of OPH in silk fibroin leads to stabilization of OPH activity under a variety of conditions that would otherwise reduce free enzyme activity, such as elevated temperature, UV light exposure and the presence of detergent. Silk fibroin entrapment of OPH also allowed for its dispersal into a polyurethane-based coating that retained organophosphate hydrolysis activity after formulation, application and drying. Together, the data presented here demonstrate the utility of silk fibroin entrapment for the protection of OPH activity under a variety of environmental conditions.

Review physical and chemical aspects of stabilization of compounds in silk.

The challenge of stabilization of small molecules and proteins has received considerable interest. The biological activity of small molecules can be lost as a consequence of chemical modifications, while protein activity may be lost due to chemical or structural degradation, such as a change in macromolecular conformation or aggregation. In these cases, stabilization is required to preserve therapeutic and bioactivity efficacy and safety. In addition to use in therapeutic applications, strategies to stabilize small molecules and proteins also have applications in industrial processes, diagnostics, and consumer products like food and cosmetics. Traditionally, therapeutic drug formulation efforts have focused on maintaining stability during product preparation and storage. However, with growing interest in the fields of encapsulation, tissue engineering, and controlled release drug delivery systems, new stabilization challenges are being addressed; the compounds or protein of interest must be stabilized during: (1) fabrication of the protein or small molecule-loaded carrier, (2) device storage, and (3) for the duration of intended release needs in vitro or in vivo. We review common mechanisms of compound degradation for small molecules and proteins during biomaterial preparation (including tissue engineering scaffolds and drug delivery systems), storage, and in vivo implantation. We also review the physical and chemical aspects of polymer-based stabilization approaches, with a particular focus on the stabilizing properties of silk fibroin biomaterials.