AlphaFold2 modeling and molecular dynamics simulations of an intrinsically disordered protein.

We use AlphaFold2 (AF2) to model the monomer and dimer structures of an intrinsically disordered protein (IDP), Nvjp-1, assisted by molecular dynamics (MD) simulations. We observe relatively rigid dimeric structures of Nvjp-1 when compared with the monomer structures. We suggest that protein conformations from multiple AF2 models and those from MD trajectories exhibit a coherent trend: the conformations of an IDP are deviated from each other and the conformations of a well-folded protein are consistent with each other. We use a residue-residue interaction network (RIN) derived from the contact map which show that the residue-residue interactions in Nvjp-1 are mainly transient; however, those in a well-folded protein are mainly persistent. Despite the variation in 3D shapes, we show that the AF2 models of both disordered and ordered proteins exhibit highly consistent profiles of the pLDDT (predicted local distance difference test) scores. These results indicate a potential protocol to justify the IDPs based on multiple AF2 models and MD simulations.

Silky Liquid Metal Electrodes for On-Skin Health Monitoring.

Next generation on-skin electrodes will require soft, flexible, and gentle materials to provide both high-fidelity sensing and wearer comfort. However, many commercially available on-skin electrodes lack these key properties due to their use of rigid hardware, harsh adhesives, uncomfortable support structures, and poor breathability. To address these challenges, this work presents a new device paradigm by joining biocompatible electrospun spider silk with printable liquid metal to yield an incredibly soft and scalable on-skin electrode that is strain-tolerant, conformable, and gentle on-skin. These electrodes, termed silky liquid metal (SLiM) electrodes, are found to be over five times more breathable than commercial wet electrodes, while the silk's intrinsic adhesion mechanism allows SLiM electrodes to avoid the use of harsh artificial adhesives, potentially decreasing skin irritation and inflammation over long-term use. Finally, the SLiM electrodes provide comparable impedances to traditional wet and other liquid metal electrodes, offering a high-fidelity sensing alternative with increased wearer comfort. Human subject testing confirmed the SLiM electrodes ability to sense electrophysiological signals with high fidelity and minimal irritation to the skin. The unique properties of the reported SLiM electrodes offer a comfortable electrophysiological sensing solution especially for patients with pre-existing skin conditions or surface wounds.

Investigation of Surface Integrity Induced by Ultra-Precision Grinding and Scratching of Glassy Carbon.

Glassy carbon provides material characteristics that make it a promising candidate for use as a mould material in precision glass moulding. However, to effectively utilize glassy carbon, a thorough investigation into the machining of high-precision optical surfaces is necessary, which has not been thoroughly investigated. This research analyses the process of material removal and its resulting surface integrity through the use of nano-scratching and ultra-precision grinding. The nano-scratching process begins with ductile plastic deformation, then progresses with funnel-shaped breakouts in the contact zone, and finally concludes with brittle conchoidal breakouts when the cutting depth is increased. The influence of process factors and tool-related parameters resulting from grinding has discernible impacts on the ultimate surface roughness and topography. Enhancing the cutting speed during cross-axis kinematic grinding results in improved surface roughness. Increasing the size of diamond grains and feed rates leads to an increase in surface roughness. An achievable surface roughness of Ra < 5 nm together with ductile-regime grinding behaviour meet optical standards, which makes ultra-precision grinding a suitable process for optical surface generation.

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.

Accurate prediction by AlphaFold2 for ligand binding in a reductive dehalogenase and implications for PFAS (per- and polyfluoroalkyl substance) biodegradation.

Despite the success of AlphaFold2 (AF2), it is unclear how AF2 models accommodate for ligand binding. Here, we start with a protein sequence from Acidimicrobiaceae TMED77 (T7RdhA) with potential for catalyzing the degradation of per- and polyfluoroalkyl substances (PFASs). AF2 models and experiments identified T7RdhA as a corrinoid iron-sulfur protein (CoFeSP) which uses a norpseudo-cobalamin (BVQ) cofactor and two Fe4S4 iron-sulfur clusters for catalysis. Docking and molecular dynamics simulations suggest that T7RdhA uses perfluorooctanoic acetate (PFOA) as a substrate, supporting the reported defluorination activity of its homolog, A6RdhA. We showed that AF2 provides processual (dynamic) predictions for the binding pockets of ligands (cofactors and/or substrates). Because the pLDDT scores provided by AF2 reflect the protein native states in complex with ligands as the evolutionary constraints, the Evoformer network of AF2 predicts protein structures and residue flexibility in complex with the ligands, i.e., in their native states. Therefore, an apo-protein predicted by AF2 is actually a holo-protein awaiting ligands.

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 Investigation into pH Dependent Metal Binding of the Intrinsically Disordered Worm Jaw Protein, Nvjp-1.

Sclerotization of the Nereis virens jaw is mediated by metal binding to the histidine-rich jaw protein, Nvjp-1. Previous studies showed that the mechanical properties of Nvjp-1 hydrogels could be modulated with zinc binding as well as the associated anion. Here, we show that the mechanical properties of Nvjp-1 hydrogels can be modulated by pH and that zinc binding to Nvjp-1 is stable at both acidic and alkaline pH conditions. To probe the mechanism of Zn2+ binding to Nvjp-1 at different pH conditions, we utilized all atom molecular dynamics simulations employing a polarizable force field. At low pH conditions, polar residues predominantly interacted with Zn2+, with at most two residues interacting with a given zinc ion. Surprisingly, little to no Zn2+ binding was observed with the abundant Nvjp-1 acidic residues, which form salt-bridges with the protonated histidines to effectively block their binding to Zn2+ ions. As the pH was shifted to alkaline conditions, Zn2+ binding residues reconfigured to form additional coordination bonds with histidine, resulting in a reduction in the radius of gyration that correlated with hydrogel sclerotization. Furthermore, acetate ions were shown to facilitate the capture of zinc ions through association with protonated histidines at low pH, freeing acidic residues to interact with Zn2+ ions and increasing the number of Zn2+ ions that diffuse into the Nvjp-1 interior. Thus, these studies provide valuable molecular insights into how amino acid residues in Nvjp-1 manage metal salt binding and coordination in hydrogels as a function of the pH and ionic environments.

Efficacy and Safety of Ciprofloxacin Plus Fluocinolone Acetonide Among Patients With Acute Otitis Externa: A Randomized Clinical Trial.

Importance: Ciprofloxacin, 0.3%, plus fluocinolone acetonide, 0.025%, otic solution seems to be efficacious and safe in treating acute otitis externa (AOE) compared with ciprofloxacin, 0.3%, or fluocinolone acetonide, 0.025%, otic solution alone. Objective: To evaluate the superiority of ciprofloxacin, 0.3%, plus fluocinolone acetonide, 0.025%, otic solution compared with ciprofloxacin, 0.3%, or fluocinolone acetonide, 0.025%, otic solution alone in treating AOE. Design, Setting, and Participants: A phase 3 randomized, double-blind, active-controlled clinical trial was conducted between August 1, 2017, and September 14, 2018, at 36 centers in the US. The study population comprised 493 patients aged 6 months or older with AOE of less than 21 days' duration with otorrhea, moderate or severe otalgia, and edema, as well as a Brighton grading of II or III (tympanic membrane obscure but without systemic illness). Statistical analysis was performed from November 14, 2018, to February 14, 2019. Interventions: Participants were randomly assigned to receive ciprofloxacin plus fluocinolone, ciprofloxacin, or fluocinolone twice daily for 7 days and were evaluated on day 1 (visit 1; baseline), days 3 to 4 (visit 2; conducted via telephone), days 8 to 10 (visit 3; end of treatment), and days 15 to 17 (visit 4; test of cure). Main Outcomes and Measures: The primary outcome was therapeutic cure (clinical and microbiological) at the end of the treatment period. The principal secondary end point was the time to end of ear pain. Efficacy analyses were conducted in the microbiological intent-to-treat population, clinical intent-to-treat population, and microbiological intent-to-treat population with Pseudomonas aeruginosa and Staphylococcus aureus. Results: A total of 493 patients (254 female patients [51.5%]; mean [SD] age, 38.2 [23.1] years) were randomized (197 to receive ciprofloxacin plus fluocinolone, 196 to receive ciprofloxacin, and 100 to receive fluocinolone). Therapeutic cure in the modified intent-to-treat population with ciprofloxacin plus fluocinolone (63 of 103 [61.2%]) was statistically comparable to that of ciprofloxacin (49 of 91 [53.8%]; difference in response rate, 7.3%; 95% CI, -6.6% to 21.2%; P = .30) and fluocinolone (20 of 45 [44.4%]; difference in response rate, 16.7%; 95% CI, -0.6% to 34.0%; P = .06) at visit 3 and significantly superior to ciprofloxacin at visit 4 (90 of 103 [87.4%] vs 69 of 91 [75.8%]; difference in response rate, 11.6%; 95% CI, 0.7%-22.4%; P = .04). A statistically faster resolution of otalgia was achieved among patients treated with ciprofloxacin plus fluocinolone (median, 5.0 days [range, 4.2-6.3 days]) vs ciprofloxacin (median, 5.9 days [range, 4.3-7.3 days]; 95% CI, 4.3-7.3 days; P = .002) or fluocinolone (median, 7.7 days [range, 6.7-9.0 days]; 95% CI, 6.7-9.0 days; P < .001). Ciprofloxacin plus fluocinolone demonstrated statistical superiority in sustained microbiological response vs ciprofloxacin (94 of 103 [91.3%] vs 74 of 91 [81.3%]; difference in response rate, 9.9%; 95% CI, 0.3%-19.6%; P = .04) and fluocinolone (34 of 45 [75.6%]; difference in response rate, 15.7%; 95% CI, 2.0%-29.4%; P = .01) and in the microbiological outcome vs fluocinolone by visit 3 (99 of 103 [96.1%] vs 37 of 45 [82.2%]; difference in response rate, 13.9%; 95% CI, 2.1%-25.7%; P = .01) and ciprofloxacin by visit 4 (97 of 103 [94.2%] vs 77 of 91 [84.6%]; difference in response rate, 9.6%; 95% CI, 0.9%-18.2%; P = .02). Fifteen adverse events related to study medications were registered, all of which were mild or moderate. Conclusions and Relevance: Ciprofloxacin, 0.3%, plus fluocinolone acetonide, 0.025%, otic solution was efficacious and safe in treating AOE but did not demonstrate superiority vs ciprofloxacin, 0.3%, or fluocinolone acetonide, 0.025%, otic solutions alone in the main study end point of therapeutic cure. Trial Registration: ClinicalTrials.gov Identifier: NCT03196973.

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.

AlphaFold2 models indicate that protein sequence determines both structure and dynamics.

AlphaFold 2 (AF2) has placed Molecular Biology in a new era where we can visualize, analyze and interpret the structures and functions of all proteins solely from their primary sequences. We performed AF2 structure predictions for various protein systems, including globular proteins, a multi-domain protein, an intrinsically disordered protein (IDP), a randomized protein, two larger proteins (> 1000 AA), a heterodimer and a homodimer protein complex. Our results show that along with the three dimensional (3D) structures, AF2 also decodes protein sequences into residue flexibilities via both the predicted local distance difference test (pLDDT) scores of the models, and the predicted aligned error (PAE) maps. We show that PAE maps from AF2 are correlated with the distance variation (DV) matrices from molecular dynamics (MD) simulations, which reveals that the PAE maps can predict the dynamical nature of protein residues. Here, we introduce the AF2-scores, which are simply derived from pLDDT scores and are in the range of [0, 1]. We found that for most protein models, including large proteins and protein complexes, the AF2-scores are highly correlated with the root mean square fluctuations (RMSF) calculated from MD simulations. However, for an IDP and a randomized protein, the AF2-scores do not correlate with the RMSF from MD, especially for the IDP. Our results indicate that the protein structures predicted by AF2 also convey information of the residue flexibility, i.e., protein dynamics.

Draft Genome Sequence of the Bacterium Delftia acidovorans Strain D4B, Isolated from Soil.

Delftia acidovorans strain D4B is an aerobic bacterium within the Betaproteobacteria lineage that was isolated from soil. The genome size is 6.26 Mbp, with a G+C content of 67%. The genome encodes enzymes potentially involved in the degradation of fluorinated compounds.

Competition-Enhanced Ligand Selection to Screen for DNA Aptamers for Spherical Gold Nanoparticles.

The Competition-Enhanced Ligand Selection (CompELS) approach was used to identify aptamer candidates for spherical gold nanoparticles (AuNPs). This approach differs from conventional Systematic Evolution of Ligands by EXponential enrichment (SELEX)-based aptamer screening by eliminating repeated elution and polymerase chain reaction (PCR) amplification steps of bound candidate sequences between each selection round to continually enrich the candidate aptamer pool with oligonucleotides remaining from an earlier SELEX selection round. Instead, a new pool of unenriched oligonucleotides is added during each CompELS selection round to compete with existing target-bound oligonucleotides species for target binding sites. In this study, 24 aptamer candidates for AuNPs were identified using the CompELS approach and then compared to reveal similarities in their primary structures and their predicted secondary structures. No strong patterns in individual base identities (position-dependent) nor in segments of consecutive bases (independent of position) prevailed among the identified sequences. Motifs in predicted secondary structures, on the other hand, were shared among otherwise unrelated aptamer sequences. These motifs were revealed using a systematic classification and enumeration of distinct secondary structure elements, namely, hairpins, duplexes, single-stranded segments, interior loops, bulges, and multibranched loops.

Capsule and Sprinkle Formulations of Lubiprostone Are Not Biologically Similar in Patients with Functional Constipation.

INTRODUCTION: Lubiprostone capsules are approved for managing three different chronic constipation conditions. A "sprinkle" formulation may facilitate use in individuals with difficulty swallowing capsules. Our objective was to evaluate the bioequivalence, pharmacokinetics (PK), and bioavailability of lubiprostone sprinkles vs lubiprostone capsules, compared with placebo. METHODS: A 1-week randomized, placebo-controlled, double-blinded, bioequivalence study (study 302) and a single-dose PK and bioavailability crossover study (study 304) were conducted. In study 302, 522 subjects with chronic constipation were randomized to lubiprostone sprinkle 24 µg twice daily (BID), lubiprostone capsule 24 µg BID, or placebo. The primary efficacy endpoint was observed spontaneous bowel movement (SBM) counts (equivalence defined as showing the 90% confidence interval [CI] of the "between-group SBM ratio" to be contained within 0.8-1.25). Study 304 included two cohorts of healthy volunteers randomized to a single 48-µg lubiprostone dose, sprinkle, or capsule (n = 35) or to a single 48-µg sprinkle dose, in fed or fasted state (n = 14). RESULTS: Both lubiprostone formulations significantly improved SBM count (sprinkle, 4.82 ± 3.66, P = 0.002; capsule, 5.74 ± 3.79, P < 0.0001) vs placebo (3.68 ± 2.16), but equivalent efficacy was not demonstrated, with a 90% CI for the SBM count ratio of 0.69-0.95. Quantifiable PK data on lubiprostone were limited; however, overall exposure to the M3 metabolite was approximately 44% higher with sprinkles vs capsules under fasted conditions (geometric mean ratio 1.441 [90% CI, 1.166, 1.782]), and exposure with the sprinkle formulation was 11% lower in the fed state vs the fasted state (geometric mean ratio 0.888 [90% CI, 0.675, 1.168]). Both formulations were generally well tolerated. CONCLUSION: Despite the significant improvement in SBM counts vs placebo, the sprinkle formulation did not demonstrate bioequivalence to the capsule formulation in either pharmacodynamic or PK key parameters. TRIAL REGISTRATION: Study 302: ClinicalTrials.gov identifier, NCT03097861; https://www.clinicaltrials.gov/ct2/show/NCT03097861 ; Study 304: ClinicalTrials.gov identifier, NCT03010631; https://www.clinicaltrials.gov/ct2/show/NCT03010631 .

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.