Hydrophobic Substrates Research Articles

Gravity induced shape effects on the time-dependent evaporation of pendant drops

The paper presents a method to model the time-dependent evaporation of pendant drops taking into account the effect of drop deformation induced by gravity. The model is based on the solution to the time-dependent drop mass and energy conservation equations, where the mass and energy fluxes through the gas mixture are numerically evaluated for a range of Bond numbers and contact angles. The evaporation characteristics of pendant and sessile drops on hydrophobic and hydrophilic substrates are compared in terms of evaporation times and evaporative cooling, for both constant contact angle and constant contact radius modes.

Cross-Coupling Reaction of Hydrophobic Substrates in Water: Micellar Catalysis with Macromolecular Surfactants

Cross-Coupling Reaction of Hydrophobic Substrates in Water: Micellar Catalysis with Macromolecular Surfactants

Surface charge density and induced currents by self-charging sliding drops.

Spontaneous charge separation in drops sliding over a hydrophobized insulator surface is a well-known phenomenon and lots of efforts have been made to utilize this effect for energy harvesting. For maximizing the efficiency of such devices, a comprehensive understanding of the dewetted surface charge would be required to quantitatively predict the electric current signals, in particular for drop sequences. Here, we use a method based on mirror charge detection to locally measure the surface charge density after drops move over a hydrophobic surface. For this purpose, we position a metal electrode beneath the hydrophobic substrate to measure the capacitive current induced by the moving drop. Furthermore, we investigate drop-induced charging on different dielectric surfaces together with the surface neutralization processes. The surface neutralizes over a characteristic time, which is influenced by the substrate and the surrounding environment. We present an analytical model that describes the slide electrification using measurable parameters such as the surface charge density and its neutralization time. Understanding the model parameters and refining them will enable a targeted optimization of the efficiency in solid-liquid charge separation.

New insights into coordination-cage based catalysis.

This review article summarises work from the author's group on catalysis using coordination cages over the (approximate) period 2018-2024. Recent insights discussed include (i) the general mechanism of catalysis, which involves co-location of reaction partners using orthogonal interactions involving the cage cavity (neutral hydrophobic substrates) and the surface anion-based reaction partners; (ii) the role of the cage exterior surface in facilitating catalysis in some cases; (iii) quantitative analysis of anion-binding to the cage surface, as a complement to measurement of binding constants of neutral guests inside the cavity; (iv) a new type of redox-based catalysis using reactive oxygen species, which are generated by reaction of oxidants such as H2O2 and HSO5- with Co(II)/Co(III) redox couples in the cage superstructure. Collectively the results discussed provide signficant new possibilities for further exploration of catalysis using supramolecular assemblies.

Graphitic nanoflakes modulate the structure and binding of human amylin.

Human amylin is an inherently disordered protein whose ability to form amyloid fibrils is linked to the onset of type II diabetes. Graphitic nanomaterials have potential in managing amyloid diseases as they can disrupt protein aggregation processes in biological settings, but optimising these materials to prevent fibrillation is challenging. Here, we employ bias-exchange molecular dynamics simulations to systematically study the structure and adsorption preferences of amylin on graphitic nanoflakes that vary in their physical dimensions and surface functionalisation. Our findings reveal that nanoflake size and surface oxidation both influence the structure and adsorption preferences of amylin. The purely hydrophobic substrate of pristine graphene (PG) nanoflakes encourages non-specific protein adsorption, leading to unrestricted lateral mobility once amylin adheres to the surface. Particularly on larger PG nanoflakes, this induces structural changes in amylin that may promote fibril formation, such as the loss of native helical content and an increase in β-sheet character. In contrast, oxidised graphene nanoflakes form hydrogen bonds between surface oxygen sites and amylin, and as such restricting protein mobility. Reduced graphene oxide (rGO) flakes, featuring lower amounts of surface oxidation, are amphiphilic and exhibit substantial regions of bare carbon which promote protein binding and reduced conformational flexibility, leading to conservation of the native structure of amylin. In comparison, graphene oxide (GO) nanoflakes, which are predominantly hydrophilic and have a high degree of surface oxidation, facilitate considerable protein structural variability, resulting in substantial contact area between the protein and GO, and subsequent protein unfolding. Our results indicate that tailoring the size, oxygen concentration and surface patterning of graphitic nanoflakes can lead to specific and robust protein binding, ultimately influencing the likelihood of fibril formation. These atomistic insights provide key design considerations for the development of graphitic nanoflakes that can modulate protein aggregation by sequestering protein monomers in the biological environment and inhibit conformational changes linked to amyloid fibril formation.

Production and characterization of rhamnolipid biosurfactant from thermophilic Geobacillus stearothermophilus bacterium isolated from Uhud mountain.

Biosurfactants have been given considerable attention as they are potential candidates for several biotechnological applications. In this study, a promising thermophilic biosurfactant-producing HA-2 was isolated from the volcanic and arid region of Uhud mountain, Madinah, Saudi Arabia. It was identified using 16S rRNA gene sequence analysis. The biosurfactant production ability was screened using different methods such as the drop collapse test, oil spreading test, hemolytic activity test, CTAB test, and emulsification index. The ability of rhamnolipid production by the tested strain was confirmed by the polymerase chain reaction (PCR) of rhlAB. The affinity of thermophilic HA-2 to hydrophobic substrates was also investigated. Optimization of biosurfactant production was conducted. The biological activities of produced surfactant were investigated. The isolated HA-1 was identified as Geobacillus stearothermophilus strain OR911984. It could utilize waste sunflower frying oil (WSFF) oil as a low-cost carbon source. It showed high emulsification activity (52 ± 0.0%) and positive results toward other biosurfactant screening tests. The strain showed high cell adhesion to hexane with 41.2% cell surface hydrophobicity. Fourier-transform infrared (FTIR) spectra indicated the presence of hydrophobic chains that comprise lipids, sugars, and hydrophilic glycolipid components. The optimization results showed the optimal factors included potato peel as a carbon source with 68.8% emulsification activity, yeast extract as a nitrogen source with 60% emulsification activity, a pH of 9 (56.6%), and a temperature of 50° (72%). The kinetics showed that optimum biosurfactant production (572.4 mg/L) was recorded at 5 days of incubation. The produced rhamnolipid biosurfactant showed high antimicrobial activity against some human and plant pathogenic bacterial and fungal isolates and high antioxidant activity (90.4%). In addition, it enhanced wheat (Triticum aestivum) growth, with the greatest enhancement obtained with the 5% concentration. Therefore, thermophilic G. stearothermophilus is a promising rhamnolipid biosurfactant producer that utilizes many organic wastes. The produced biosurfactant could be applied as a promising emulsifier, antimicrobial, antioxidant, and plant growth promoter.

Atomic force microscopy analysis of Pel polysaccharide- and type IV pili-mediated adhesion of Pseudomonas aeruginosa PA14 to an abiotic surface.

Type IV pili (TFP) contribute to the ability of microbes such as Pseudomonas aeruginosa to engage with and move across surfaces. We reported previously that P. aeruginosa TFP generate retractive forces of ∼30 pN and provided indirect evidence that TFP-mediated surface attachment was enhanced in the presence of the Pel polysaccharide. Here, we use different mutants defective in flagellar, Pel production or TFP production - alone or in combination - to decipher the relative contribution of these biofilm-promoting factors for P. aeruginosa adhesion. By means of atomic force microscopy (AFM), we show that mutating the flagellum (ΔflgK mutant) results in an increase in Pel polysaccharide production, but this increase in Pel does not result in an increase in surface adhesive properties compared to those previously described for the WT strain. By blocking Pel production in the ΔflgK mutant (ΔflgKΔpel), we directly show that TFP play a major role in the adhesion of the bacteria to hydrophobic AFM tips, but that the adhesion force is only slightly impaired by the absence of Pel. Inversely, performing single-cell force spectroscopy measurements with the mutant lacking TFP (ΔflgKΔpilA) reveals that the Pel can modulate the attachment of the bacteria to a hydrophobic substrate in a time-dependent manner. Finally, little adhesion was detected for the ΔflgKΔpilAΔpelA triple mutant, suggesting that both TFP and Pel polysaccharide make a substantial contribution to bacteria-substratum interaction events. Altogether, our data allow us to decipher the relative contribution of Pel and TFP in the early attachment by P. aeruginosa.

Theoretical calculation on degradation mechanism of novel copolyesters under CALB enzyme

Poly(butylene succinate-co-furandicarboxylate) (PBSF) and poly(butylene adipate-co-furandicarboxylate) (PBAF) are novel furandicarboxylic acid-based biodegradable copolyesters with great potential to replace fossil-derived terephthalic acid-based copolyesters such as poly(butylene succinate-co-terephthalate) (PBST) and poly(butylene adipate-co-terephthalate) (PBAT). In this study, quantum chemistry techniques after molecular dynamics simulations are employed to investigate the degradation mechanism of PBSF and PBAF catalyzed by Candida antarctica lipase B (CALB). Computational analysis indicates that the catalytic reaction follows a four-step mechanism resembling the ping-pong bibi mechanism, with the initial two steps being acylation reactions and the subsequent two being hydrolysis reactions. Notably, the first step of the hydrolysis is identified as the rate-determining step. Moreover, by introducing single-point mutations to expand the substrate entrance tunnel, the catalytic distance of the first acylation step decreases. Additionally, energy barrier of the rate-determining step is decreased in the PBSF system by site-directed mutations on key residues increasing hydrophobicity of the enzyme's active site. This study unprecedently show the substrate binding pocket and hydrophobicity of the enzyme's active site have the potential to be engineered to enhance the degradation of copolyesters catalyzed by CALB.

A Hypothetical Approach to Concentrate Microorganisms from Human Urine Samples Using Paper-Based Adsorbents for Point-of-Care Molecular Assays.

This hypothesis demonstrates that the efficiency of loop-mediated isothermal amplification (LAMP) for nucleic acid detection can be positively influenced by the preconcentration of microbial cells onto hydrophobic paper surfaces. The mechanism of this model is based on the high affinity of microbes towards hydrophobic surfaces. Extensive studies have demonstrated that hydrophobic surfaces exhibit enhanced bacterial and fungal adhesion. By exploiting this inherent affinity of hydrophobic paper substrates, the preconcentration approach enables the adherence of a greater number of target cells, resulting in a higher concentration of target templates for amplification directly from urine samples. In contrast to conventional methods, which often involve complex procedures, this approach offers a simpler, cost-effective, and user-friendly alternative. Moreover, the integration of cell adhesion, LAMP amplification, and signal readout within paper origami-based devices can provide a portable, robust, and highly efficient platform for rapid nucleic acid detection. This innovative hypothesis holds significant potential for point-of-care (POC) diagnostics and field surveillance applications. Further research and development in this field will advance the implementation of this technology, contributing to improved healthcare systems and public health outcomes.

The Importance of Substrate Pore Size and Hydrophobicity in Gas Diffusion Electrodes for CO2 Reduction

Electrochemical CO2 reduction (CO2RR) is a promising way to convert detrimental CO2 emissions into sustainable fuels and chemicals, and move closer to a circular carbon economy. 1 To compete with traditional fuel/chemical production routes, electrocatalysts need to be highly active, selective towards a desired product, and stable. High activities can be achieved with gas diffusion electrodes (GDEs) that provide gaseous CO2 to the catalyst, however, product selectivity and stability still need to be improved before industrial implementation. In this work, we show that the selectivity and stability of Ag and Cu GDEs can be tuned by acting on the pore size and hydrophobicity of their polymeric substrates.2,3 We rationalize these findings with the extent to which electrolyte penetrates the polymer-based GDEs, which depends on both substrate pore size and hydrophobicity and is quantified by the water entry pressure. GDEs with larger pore size promote electrolyte penetration (low water entry pressure) and, in the Ag case, yield GDEs with poor CO selectivity and stability (Fig. 1). In contrast, GDEs with small pore size show a much higher resistance to electrolyte penetration (high water entry pressure), thus yielding a greatly improved Faradaic efficiency for CO (up to 95% at 100 mA/cm2 in neutral electrolyte) and remarkable long-term stability (97% of initial CO selectivity retained after > 40 h). In the Cu case, we observe a strong enhancement in C2H4 selectivity when employing GDE substrates with small pores and strong hydrophobicity (up to 55% Faradaic efficiency in neutral electrolyte at 200 mA/cm2 for > 3 h). Both CO2 and CO reduction reactions indicate that mass transport limitations are present for all GDEs, but can be mitigated by GDE's with small pore size. Our results emphasize the importance of substrate microstructure on GDE product selectivity and stability during CO2RR, and represent a new scalable strategy to improve GDE performance. References 1A. Senocrate, C. Battaglia, J. Energy Storage 2021, 36, 102373 2A. Senocrate, F. Bernasconi, D. Rentsch, K. Kraft, M. Trottmann, A. Wichser, D. Bleiner, C. Battaglia, ACS Appl. Energy Mater. 2022, 5, 14504 3F. Bernasconi, A. Senocrate, C. Battaglia et al., in preparation Figure 1

Behavior of a sessile droplet over dielectric infused hydrophobic surface under direct current electric field

The manipulation of sessile droplets on hydrophobic surfaces with high controllability, accuracy, and flexibility is vital for various applications of engineering sciences and technology. In this research, the combined effects of a uniform electric field, dielectric infused surface (DIS), and surfactants were investigated for the manipulation and control of sessile droplets on hydrophobic substrates. DIS reduced surface adhesion and enabled the action of electrohydrodynamic and electrophoretic forces. Experimental analysis revealed three different modes of droplet behavior on DIS under varying electro-physical conditions: elongation without motion, elongation with motion, or dispersion. These modes were observed for surfactant concentrations below the critical micelle concentration (CCMC), while elongation leading to restricted spreading of droplet occurred above CCMC. The modes were mapped in the parametric space of electric capillary number (Cae) vs. non-dimensional surfactant concentration (C* = Cs /CCMC), with Cae representing the ratio of interfacial electric to capillary stresses and Cs representing the surfactant concentration. A simple theoretical analysis based on interfacial electric and capillary stress balance distinguished between the stable and unstable configurations. This research contributes to advancing the understanding of droplet manipulation and control, which are critical in emerging microfluidic or biological applications.

Constructing nanofiltration membrane on hydrophobic PVDF and PTFE substrates via reverse interfacial polymerization

Polyvinylidene fluoride (PVDF) and polytetrafluoroethylene(PTFE) porous membranes are ideal substrates for preparing thin-film composite (TFC) polyamide (PA) membranes with improved solvent resistance. However, it remains difficult to construct PA skin layers on PVDF and PTFE substrates via conventional interfacial polymerization (IP) due to the hydrophobic nature of these materials. To address this challenge, a reverse IP process was proposed to construct a defect-free PA skin layer on PVDF and PTFE substrates, in which the hydrophobic PVDF and PTFE substrates were soaked with the organic phase to ensure uniform coverage of reacted solution on the substrates. This novel strategy can effectively tackle the issue of uneven wetting of the aqueous phase on hydrophobic substrates in the conventional IP process. The resultant TFC membranes (i.e. Mrev-PVDF and Mrev-PTFE) exhibit excellent nanofiltration (NF) performance in both aqueous and organic solutions. Mrev-PVDF and Mrev-PTFE have MgCl2 rejections of 96.12% and 95.17%, alongside the water permeances of 12.8 LMH/bar and 11.2 LMH/bar, respectively (Mrev-PTFE was activated with DMF). It is further shown that Mrev-PVDF and Mrev-PTFE could also reject 99.4% and 98.5% of Congo red in methanol solution at solvent permeances of over 3.3 LMH/bar, while they also perform excellently in other polar protic solvents. Consequently, this work opens a new window for constructing high-performance TFC PA membranes on hydrophobic substrates and expands the application of the TFC PA NF membrane.

Liquid-liquid surfactant partitioning drives dewetting of oil from hydrophobic surfaces

HypothesisSessile droplets solubilizing in surfactant solution are frequently encountered in practice, but the factors governing their non-equilibrium dynamics are not well understood. Here, we investigate mechanisms by which solubilizing, sessile oil droplets in aqueous surfactant solution dewet from hydrophobic substrates and spread on hydrophilic substrates. ExperimentsWe quantify the dependence of droplet contact line dynamics on drop size and oil, surfactant, and substrate chemistries. We consider halogenated alkane oils as well as aromatic oils and focus on common nonionic nonylphenol ethoxylate surfactants. We correlate these results with measurements of the interfacial tensions. FindingsCounter-intuitively, under a range of conditions, we observe complete dewetting of oil from hydrophobic substrates but spreading on hydrophilic substrates. The timescales needed to reach a steady-state contact angle vary widely, with some droplets examined taking over a day. We find that surfactant surface adsorption governs the contact angle on shorter timescales, while partitioning of surfactant from water to oil, and oil solubilization into the water, act on longer timescales to facilitate the complete dewetting. Understanding of the role played by surfactant and oil transport presents opportunities for tailoring sessile droplet behaviors and controlling droplet dynamics under conditions that would previously not have been considered.

Asymmetric Synthesis of N-Alkyl Amino Acids through a Biocatalytic Dynamic Kinetic Resolution of PEGylated N-Alkyl Amino Esters.

The first examples of a practical procedure for a lipase-catalyzed dynamic kinetic resolution of PEGylated N-alkyl amino esters is reported. This method allows for the preparation of a broad range of aromatic and aliphatic enantiomerically enriched N-alkyl unnatural amino acids in up to 98% yield and 99% ee. We have found that PEGylated esters have a significant solubility advantage and improved reactivity over traditional hydrophobic lipase substrates, thereby allowing for efficient and scalable dynamic kinetic resolution (DKR) under aqueous conditions.

High Voltages in Sliding Water Drops.

Water drops on insulating hydrophobic substrates can generate electric potentials of kilovolts upon sliding for a few centimeters. We show that the drop saturation voltage corresponds to an amplified value of the solid-liquid surface potential at the substrate. The amplification is given by the substrate geometry, the drop and substrate dielectric properties, and the Debye length within the liquid. Next to enabling an easy and low-cost way to measure surface- and zeta- potentials, the high drop voltages have implications for energy harvesting, droplet microfluidics, and electrostatic discharge protection.

Potential brewer’s spent grain as a carbon source alternative for biosurfactant production by Rhodotorula mucilaginosa (LBP4)

This study promoted the valorization of brewer’s spent grain (BSG) by using it as an alternative and low-cost carbon source in the production of biosurfactant by Rhodothorula mucilaginosa (LPB4) in an optimized process. The raw BSG was characterized: moisture content (80.0%), insoluble and soluble lignin (29.25%), proteins (6.43%), ash (4.22%), cellulose (47.37%) and pH (6.06), then to verify the increase of reducing sugars, BSG was tested by microwave-assisted alkali and diluted acid pretreatments and then the BSG with and without pretreatment were subjected to enzymatic hydrolysis. The microwave-assisted alkali, followed by enzymatic hydrolysis, achieved 181 mg of sugar.g-1 of BSG and was the most effective. The hydrolysate was used as a carbon source for the biosurfactant production assays and optimized under the following conditions: 30ºC, 120 rpm, 2.5 g.L- 1 of sugar, and pH 4. The biosurfactant was able to emulsify (%E24) different hydrophobic substrates, which were as follows: soybean oil (64.4%), motor oil (62.2%), kerosene (67.4%) and diesel oil (56.81%). Also, it showed stability under extreme temperatures, pH, and salinity. A critical micelle concentration (CMC) of 14.8 mg.mL- 1 was achieved with a decrease in surface tension (ST) from 71.26 mN.m-1 to 30.56 mN.m- 1. The extracted biosurfactant showed an anionic nature and structural similarities to a glycolipid. The present findings revealed that pretreated BSG may be used as a substrate in biosurfactant production using the yeast R. mucilaginosa. This is the first study regarding using LBP4 to optimize the production of biosurfactant using alkali enzymatic BSG hydrolysate.

Spatial tumor biopsy with fluorescence PCR microneedle array

Biopsy is the gold standard for tumor diagnosis as this technology provides highly detailed and reliable information on tumorigenesis and progression. Resembling the discrete wettability of desert beetles, in this study, a fluorescence polymerase chain reaction (F-PCR) microneedle array (MNA) platform was developed for efficient spatial tumor biopsy. This MNA is fabricated by the coupled strategies of bottom-up self-assembly and top-down photolithography; it comprises a hydrophobic silica nanoparticle-assembled substrate and graphene aerogel-hydrogel hybrid microneedle peaks. Benefitting from the hydrophilicity and absorption capacity of its graphene hybrid microneedle peaks, MNA can easily penetrate tissue specimens and collect tumor nucleic acid biomarkers stereoscopically. In addition, because of the discrete wettability of the platform, both tissue fluids and PCR liquids can be easily removed from the substrate, and each microneedle peak is similar to an independent island for directly conducting F-PCR reactions for tumor marker discovery. Based on these advantages, the F-PCR-MNA platform was demonstrated to be ideal for detecting DNA biomarkers of lung carcinoma in standard solutions, mouse tissue samples, and clinical specimens, thus indicating its practical potential as an innovative tumor biopsy system.

Development of Janus membranes with asymmetric wettability for desalination of impaired seawater by direct contact membrane distillation

Membrane distillation (MD) is an emerging technology for direct seawater desalination. The widely employed hydrophobic membranes are susceptible to pore wetting/ fouling in the presence of organic contaminants in seawater. Here, we demonstrate a facile method of preparing Janus membranes with hydrophilic/hydrophobic faces having excellent anti-fouling and anti-wetting properties. The hydrophobic substrate is a PVDF-co-HFP membrane incorporating fluoroalkylsilane (FAS) grafted hydrophobic MIL-53(Al)- a form of metal organic framework (h-MIL-53(Al)), and the hydrophilic coating is prepared by the direct deposition of polydopamine (PDA) (top layer). The optimum membrane exhibited a stable flux of 11 L/m2h and permeate conductivity ∼10 µS/cm for up to 60 h of seawater desalination. The anti-wetting property of the Janus membrane was demonstrated from the stable performance when challenging the membrane with impaired seawater containing low surface tension compounds such as sodium dodecyl sulphate (SDS) and propylene glycol (PG), and oil (hexadecane). The prepared membrane exhibited wetting resistance of 45 h and 18 h when feed was seawater containing 0.3 mM SDS and 3 wt% PG, respectively. The membrane displayed excellent resistance to fouling for desalination from SDS-stabilized hexadecane (500 ppm)/seawater feeds for up to 50 h (5 cycles). The membrane fabricated in this study holds the potential for seawater desalination.

Waterborne spontaneous and robust coating of POSS nanoparticles on hydrophobic surfaces for application as an advanced separator in lithium ion batteries

Waterborne spontaneous and robust coating of the catechol-functionalized polyoctahedral silsesquioxane (CA-POSS) is studied on the surface of hydrophobic substrates as a model organic-inorganic hybrid material. The CA-POSS was synthesized at room temperature, which readily produces an instant thin layer coating on the hydrophobic substrates such as mica film and polyethylene (PE) separator. The CA-POSS instantly forms nano-scale level coating with robust adhesion upon contact with the substrate surfaces in a basic aqueous medium at ambient conditions, unlike common coating methods that use prepared POSS particle dispersion. The surface roughness of the CA-POSS coated PE separator (PE-CAP) and mica was observed in AFM analysis. The PE-CAP separator showed highly enhanced hydrophilicity, electrolyte wettability, mechanical strength, and thermal stability. The PE-CAP separator is studied in lithium ion batteries (LIBs) using LiCoO2 cathode and Lithium metal anode has shown the highest specific capacity of ∼171.3 mAh g−1 with capacity retention of ∼99 % after 100 cycles in comparison to pristine PE separator (∼159.4 mAh g−1, 92 %).

Rational surface charge engineering of haloalkane dehalogenase for boosting the enzymatic performance in organic solvent solutions

Biocatalysis in organic solvents (OSs) has numerous important applications, but native enzymes in OSs often exhibit limited catalytic performance. Herein, we proposed a computation-aided surface charge engineering strategy to improve the catalytic performance of haloalkane dehalogenase DhaA in OSs based on the energetic analysis of substrate binding to the DhaA surface. Several variants with enhanced OS resistance were obtained by replacing negative charged residues on the surface with positive charged residue (Arg). Particularly, a four-substitution variant E16R/E93R/E121R/E257R exhibited the best catalytic performance (five-fold improvement in OS resistance and seven-fold half-life increase in 40% (vol) dimethylsulfoxide). As a result, the overall catalytic performance of the variant could be at least 26 times higher than the wild-type DhaA. Fluorescence spectroscopy and molecular dynamics simulation studies revealed that the residue substitution mainly enhanced OS resistance from four aspects: (a) improved the overall structural stability, (b) increased the hydrophobicity of the local microenvironment around the catalytic triad, (c) enriched the hydrophobic substrate around the enzyme molecule, and (d) lowered the contact frequency between OS molecules and the catalytic triad. Our findings validate that computation-aided surface charge engineering is an effective and ingenious rational strategy for tailoring enzyme performance in OSs.