Vesicles and micelles from amphiphilic zinc(II)-cyclen complexes as highly potent promoters of hydrolytic DNA cleavage

Coupling Photoresponsive Transmembrane Ion Transport with Transition Metal Catalysis

Artificial ion transporters have been explored both as tools for studying fundamental ion transport processes and as potential therapeutics for cancer and channelopathies. Here we demonstrate that synthetic transporters may also be used to regulate the transport of catalytic metal ions across lipid membranes and thus control chemical reactivity inside lipid-bound compartments. We show that acyclic lipophilic pyridyltriazoles enable Pd(II) cations to be transported from the external aqueous phase across the lipid bilayer and into the interior of large unilamellar vesicles. In situ reduction generates Pd(0) species, which catalyze the generation of a fluorescent product. Photocaging the Pd(II) transporter allows for photoactivation of the transport process and hence photocontrol over the internal catalysis process. This work demonstrates that artificial transporters enable control over catalysis inside artificial cell-like systems, which could form the basis of biocompatible nanoreactors for applications such as drug synthesis and delivery or to mediate phototargeted catalyst delivery into cells.

Polyfluoroalkyl Chain-Based Assemblies for Biomimetic Catalysis

Amphiphobic fluoroalkyl chains are exploited for creating robust and diverse self-assembled biomimetic catalysts. Long terminal perfluoroalkyl chains (Cn F2n+1 with n=6, 8, and 10) linked with a short perhydroalkyl chains (Cm H2m with m=2 and 3) were used to synthesize several 1,4,7-triazacyclononane (TACN) derivatives, Cn F2n+1 -Cm H2m -TACN. In the presence of an equimolar amount of Zn2+ ions that coordinate the TACN moiety and drive the self-assembly into micelle-like aggregates, the critical aggregation concentration of polyfluorinated Cn F2n+1 -Cm H2m -TACN⋅Zn2+ was lowered by ∼1 order of magnitude compared to the traditional perhyroalkyl counterpart with identical carbon number of alkyl chain. When 2'-hydroxypropyl-4-nitrophenyl phosphate was used as the model phosphate substrate, polyfluorinated Cn F2n+1 -Cm H2m -TACN⋅Zn2+ assemblies showed higher affinity and catalytic activity, compared to its perhyroalkyl chain-based counterpart. Coarse-grained molecular dynamic simulations have been introduced to explore the supramolecular assembly of polyfluoroalkyl chains in the presence of Zn2+ ions and to better understand their enhanced catalytic activity.

Hydrolytic nanozymes: Preparation, properties, and applications

Hydrolytic nanozymes, as promising alternatives to hydrolytic enzymes, can efficiently catalyze the hydrolysis reactions and overcome the operating window limitations of natural enzymes. Moreover, they exhibit several merits such as relatively low cost, easier recovery and reuse, improved operating stability, and adjustable catalytic properties. Consequently, they have found relevance in practical applications such as organic synthesis, chemical weapon degradation, and biosensing. In this review, we highlight recent works addressing the broad topic of the development of hydrolytic nanozymes. We review the preparation, properties, and applications of six types of hydrolytic nanozymes, including AuNP-based nanozymes, polymeric nanozymes, surfactant assemblies, peptide assemblies, metal and metal oxide nanoparticles, and MOFs. Last, we discuss the remaining challenges and future directions. This review will stimulate the development and application of hydrolytic nanozymes.

Simultaneous quantification of serum albumin and gamma globulin using Zn(II)-metallosurfactant via a coffee ring pattern

Herein, we report interactivity and conjugate formation ability between a Zn(II)-metallosurfactant and two clinically relevant serum proteins, albumin (ALB) and γ-globulin (GGB). We found that the surfactant-ALB conjugate promotes coffee ring formation, whereas with GGB it gets suppressed, which is due to the difference in structural anisotropy and hydrophobicity of the conjugates. Additionally, validation of this biosensing platform has been established in human serum samples, and it has potential applications for on-spot rapid diagnostics in remote areas.

Experimental and computational investigation of heteroatom substitution in nucleolytic Cu(II) cyclen complexes for balancing stability and redox activity

Cu(II) complexes of cyclen-based ligands CuL¹-CuL⁶ were synthesized and characterized. The corresponding ligands L¹-L⁶ comprise different donor sets including S and O atoms. Whereas cyclen (L¹) is commercially available, L²-L⁶ were synthesized according to protocols available in the literature. Cleavage activity of the complexes towards plasmid DNA was tested in the presence and absence of ascorbate as a reducing agent (oxidative vs. hydrolytic cleavage). As previously shown, the substitution of N donor atoms with hard donor O atoms leads to efficient oxidative nucleases, but dissociation of the complex upon reduction. We thus opted for S substitution (soft donors) to stabilize the reduced Cu(I) species. Increasing the S content, however, leads to species that are difficult to reoxidize in order to ensure efficient oxidative DNA cleavage. We are showing by experimental (cyclic voltammetry) and computational means (DFT) that the rational combination of O and S atoms next to two nitrogen donors within the macrocycle (oxathiacyclen complex CuL⁶) leads to the stabilization of both redox states. The complex thus exhibits the highest oxidative DNA cleavage activity within this family of cyclen-based Cu(II) complexes - without leaching of the metal ion during reduction.

Intra- and Intermolecular Cooperativity in the Catalytic Activity of Phosphodiester Cleavage by Self-Assembled Systems Based on Guanidinylated Calix[4]arenes

The calix[4]arene scaffold, blocked in the cone conformation through alkylation with long alkyl chains, and decorated at the upper rim with four guanidine or arginine units, effectively catalyzes the cleavage of the phosphodiester bond of DNA and RNA model compounds in water. An exhaustive kinetic investigation unequivocally points to the existence of spontaneous aggregation phenomena, driven by hydrophobic effect, occurring at different critical concentrations that depend on the identity of the compound. A pronounced superiority of the assembled structures compared with the monomers in solution was observed. Moreover, the catalytically active units, clustered on the macrocyclic tetrafunctional scaffold, were proved to efficiently cooperate in the catalytic mechanism and result in improved reaction rates compared to those of the monofunctional model compounds. The kinetic analysis is also integrated and corroborated with further experiments based on fluorescence spectroscopy and light scattering. The advantage of the supramolecular assemblies based on tetrafunctional calixarenes leads to believe that the active units can cooperate not only intramolecularly but also intermolecularly. The molecules in the aggregates can probably mold, flex and rearrange but, at the same time, keep an ordered structure that favors phosphodiester bond cleavage. This dynamic preorganization can allow the catalytic units to reach a better fitting with the substrates and perform a superior catalytic activity.

Minimalistic Artificial Catalysts with Esterase-Like Activity from Multivalent Nanofibers Formed by the Self-Assembly of Dipeptides

Imitating and incorporating the multiple key structural features observed in natural enzymes into a minimalistic molecule to develop an artificial catalyst with outstanding catalytic efficiency is an attractive topic for chemists. Herein, we designed and synthesized one class of minimalistic dipeptide molecules containing a terminal -SH group and a terminal His-Phe dipeptide head linked by a hydrophobic alkyl chain with different lengths, marked as HS-C _n+1-His-Phe (n = 4, 7, 11, 15, and 17; n + 1 represents the carbon atom number of the alkyl chain). The His (-imidazole), Phe (-CO₂ ^-) moieties, the terminal -SH group, and a long hydrophobic alkyl chain were found to have important contributions to achieve high binding ability leading to outstanding absolute catalytic efficiency (k _cat/K _M) toward the hydrolysis reactions of carboxylic ester substrates.

Artificial phosphatase upon premicellar nanoarchitectonics of lanthanum complexes with long-chained imidazole derivatives

Four novel long chain-containing tridentate imidazole derivatives (Lⁿ, n = 1, 2, 3, 4) were synthesized for in situ formation of mononuclear lanthanum(III) complexes as artificial phosphodiesterases. These in-situ formed La(III) complexes (named LaLⁿ) were used to catalyze the transesterification of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP), a classic RNA model. Critical aggregation concentrations (CAC) were determined for the as-prepared tridentate imidazole derivatives as ligands and corresponding mixtures of equivalent ligand and La³⁺ ion with a mole rate of 1:1. It denotes that the introduction of La³⁺ ion increases the CAC values of imidazole derivatives by about 2 to 3 folds. Foaming test shows that the foam height is positively correlated with the length of hydrophobic chain. Transesterification of HPNP mediated by LaLⁿ nanoarchitectonics indicates that the introducing of hydrophobic chain benefits rate enhancement, showing excess three orders of magnitude acceleration under physiological conditions (pH 7.0, 25 °C). Moreover, catalytic reactivities of these La(III) complexes increased along with the increase in chain length: LaL¹ < LaL² < LaL³ < LaL⁴, suggesting a positive correlation to hydrophobic chain length.

Metal-ligand Interactions and Oligo(p-Phenylene Vinylene) Derivatives Based Supramolecular Polymer Possessing Variable Fluorescence Colors

Fluorescent supramolecular polymers combine the benefits of supramolecular polymers in terms of dynamic nature with the optoelectronic features of incorporated fluorophores. However, the majority of fluorescent supramolecular polymers can only exhibit a single fluorescent state, restricting their applications. Incorporating J-type dyes into supramolecular monomers is expected to impart supramolecular polymers with variable fluorescence colors, because the aggregation mode of J-type dyes is closely related to the formation of supramolecular polymers. Herein, we report a supramolecular polymer [M1·Zn(OTf)₂ ]_n , in which the monomer M1 contains a J-type dye, oligo(p-phenylene vinylene) (OPV) derivative, and two terpyridine ends. The M1 + Zn(OTf)₂ solutions exhibit fluorescence color changes varying from cyan to yellow-green in the monomer concentration ranging from 0.04 to 1.00 mM. Moreover, based on the outputs from laser scanning confocal microscopy (LSCM), the fluorescence color transition during the formation of supramolecular polymers is intuitively proven. Additionally, considering the close relationship between the supramolecular polymer structure and the fluorescence color, the fluorescence color can be regulated by introducing tetraethylammonium hydroxide (TBAOH) that can bind with Zn²⁺ competitively to break up the structure of the supramolecular polymer. This article is protected by copyright. All rights reserved.

Design and applications of metallo-vesicular structures using inorganic-organic hybrids

In advanced biomedical diagnosis, various supramolecular assemblies based on inorganic-organic hybrids have found great interest as functional materials. These assemblies describe a new field of metallovesicles where the introduction of metal ions enables the chemical manipulation of assemblies in terms of their structural stability, redox activity, and pH stability. Additionally, they mimic the elaborative architecture of natural liposomal assemblies and exhibit hierarchical morphologies, and promise novel functions. With the constant developments in this field, various supramolecular assemblies such as MCsomes, Polymersomes, and Metallosomes, etc. came into existence. These hybrid assemblies have been utilized for several applications such as drug delivery, MRI contrasting, DNA delivery, and catalytic activity. The key advantage of these assemblies is their ability to deliver therapeutics to specific locations due to their biomimetic properties and release their contents at the desired time. Hence, they provide a valuable platform for the treatment of a variety of diseases. Through the present article, we intend to provide insights into the latest developments made in this field. This modularity underscores the tremendous promise of supramolecular assemblies as an emerging interdisciplinary research branch at the interface of chemistry and biological sciences.

Visualizing molecular weights differences in supramolecular polymers

Molecular weight determinations play a vital role in the characterization of supramolecular polymers. They are essential to assessing the degree of polymerization, which in turn can have a significant impact on the properties of the polymer. While numerous characterization methods have been developed to estimate the number-average molecular weight (M_n) of supramolecular polymers, a simple visual method could provide advantages in terms of ease of use. We have now developed a system wherein differences in the fluorescent signature, including changes in color, allow variations in the M_n of an anion-responsive supramolecular polymer [M1·Zn(OTf)₂]_n to be readily monitored. The present visual differentiation strategy provides a tool that may be used to characterize supramolecular polymers.

Issues of molecular weight determination have been central to the development of supramolecular polymer chemistry. Whereas relationships between concentration and optical features are established for well-behaved absorptive and emissive species, for most supramolecular polymeric systems no simple correlation exists between optical performance and number-average molecular weight (M_n). As such, the M_n of supramolecular polymers have to be inferred from various measurements. Herein, we report an anion-responsive supramolecular polymer [M1·Zn(OTf)₂]_n that exhibits monotonic changes in the fluorescence color as a function of M_n. Based on theoretical estimates, the calculated average degree of polymerization (DP_cal) increases from 16.9 to 84.5 as the monomer concentration increases from 0.08 mM to 2.00 mM. Meanwhile, the fluorescent colors of M1 + Zn(OTf)₂ solutions were found to pass from green to yellow and to orange, corresponding to a red shift in the maximum emission band (λ_max). Therefore, a relationship between DP_cal and λ_max could be established. Additionally, the anion-responsive nature of the present system meant that the extent of supramolecular polymerization could be regulated by introducing anions, with the resulting change in M_n being readily monitored via changes in the fluorescent emission features.

Supramolecular chemistry in lipid bilayer membranes

Lipid bilayer membranes form compartments requisite for life. Interfacing supramolecular systems, including receptors, catalysts, signal transducers and ion transporters, enables the function of the membrane to be controlled in artificial and living cellular compartments. In this perspective, we take stock of the current state of the art of this rapidly expanding field, and discuss prospects for the future in both fundamental science and applications in biology and medicine.

Metal Complex Lipids for Fluid-Fluid Phase Separation in Coassembled Phospholipid Membranes

We demonstrate a fluid-fluid phase separation in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes using a metal complex lipid of type [Mn(L1)] (1; HL1=1-(2-hydroxybenzamide)-2-(2-hydroxy-3-formyl-5-hexadecyloxybenzylideneamino)ethane). Small amount of 1 produces two separated domains in DMPC, whose phase transition temperatures of lipids (T_c ) are both lower than that of the pristine DMPC. Variable temperature fluorescent microscopy for giant-unilamellar vesicles of DMPC/1 hybrids demonstrates that visible phase separations remain in fluid phases up to 37 °C, which is clearly over the T_c of DMPC. This provides a new dimension for the application of metal complex lipids toward controlling lipid distributions in fluid membranes.

Self-Assembled Multivalent Ag-SR Coordination Polymers with Phosphatase-Like Activity

We show herein the phosphatase-like catalytic activity of coordination polymers obtained after adding Ag⁺ -ions to thiols bearing hydrophobic alkyl chains terminated with a 1,4,7-triazacyclononane (TACN) group. The subsequent addition of Zn²⁺ -ions to the self-assembled polymers resulted in the formation of multivalent metal coordination polymers capable of catalysing the transphosphorylation of an RNA-model compound (2-hydroxypropyl-4-nitrophenyl phosphate, HPNPP) with high reactivity. Analysis of a series of metal ions showed that the highest catalytic activity was obtained when Ag⁺ -ions were used as the first metal ions to construct the backbone of the coordination polymer through interaction with the -SH group followed by Zn²⁺ -ions as the second metal ions complexed by the TACN-macrocycle. Furthermore, it was demonstrated that the catalytic activity could be modulated by changing the length of the hydrophobic alkyl chain.

R, Sissi C, Pecina A, Riccardi L, De Vivo M, Mancin F, Scrimin P. A Gold Nanoparticle Nanonuclease Relying on a Zn(II) Mononuclear Complex

Similarly to enzymes, functionalized gold nanoparticles efficiently catalyze chemical reactions, hence the term nanozymes. Herein, we present our results showing how surface-passivated gold nanoparticles behave as synthetic nanonucleases, able to cleave pBR322 plasmid DNA with the highest efficiency reported so far for catalysts based on a single metal ion mechanism. Experimental and computational data indicate that we have been successful in creating a catalytic site precisely mimicking that suggested for natural metallonucleases relying on a single metal ion for their activity. It comprises one Zn(II) ion to which a phosphate diester of DNA is coordinated. Importantly, as in nucleic acids-processing enzymes, a positively charged arginine plays a key role by assisting with transition state stabilization and by reducing the pKa of the nucleophilic alcohol of a serine. Our results also show how designing a catalyst for a model substrate (bis-p-nitrophenylphosphate) may provide wrong indications as for its efficiency when it is tested against the real target (plasmid DNA).

Binuclear metal complexes with a novel hexadentate imidazole derivative for the cleavage of phosphate diesters and biomolecules: distinguishable mechanisms

Oxidative cleavage of phosphate diesters (HPNP, BNPP) is highly faster than the hydrolytic one by binuclear metal complexes with novel imidazole derivative, producing a non-lactone phosphate monoester due to the direct attack of free radicals.

Engineering of stimuli-responsive lipid-bilayer membranes using supramolecular systems

The membrane proteins found in nature control many important cellular functions, including signal transduction and transmembrane ion transport, and these, in turn, are regulated by external stimuli, such as small molecules, membrane potential and light. Membrane proteins also find technological applications in fields ranging from optogenetics to synthetic biology. Synthetic supramolecular analogues have emerged as a complementary method to engineer functional membranes. This Review describes stimuli-responsive supramolecular systems developed for the control of ion transport, signal transduction and catalysis in lipid-bilayer-membrane systems. Recent advances towards achieving spatio-temporal control over activity in artificial and living cells are highlighted. Current challenges, the scope, limitations and future potential to exploit supramolecular systems for engineering stimuli-responsive lipid-bilayer membranes are discussed.

The Zn(II)-1,4,7-Trimethyl-1,4,7-Triazacyclononane Complex: A Monometallic Catalyst Active in Two Protonation States

In this paper, the unusual reactivity of the complex Zn(II)-1,4,7-trimethyl-1, 4,7-triazacyclononane (2) in the transesterification of the RNA-model substrate, HPNP (3), is reported. The dependence of the reactivity (k₂) with pH does not follow the characteristic bell-shape profile typical of complexes with penta-coordinated metal centers. By the contrary, two reactive species, featuring different deprotonation states, are present, with the tri-aqua complex being more reactive than the mono-hydroxy-diaqua one. Apparently, such a difference arises from the total complex charge which plays an important role in the stability of the transition state/s of the reactions. Relevant insight on the reaction mechanism were hence obtained.

Cleaving DNA-model phosphodiester with Lewis acid-base catalytic sites in bifunctional Zr-MOFs

Organophosphates exist in many biomolecules. The design of artificial nucleases for efficient P-O bond cleavage is essential for the fields of genetic engineering and molecular biology. Herein, metal-organic frameworks (MOFs) with cooperatively isolated multi-catalytic active sites were utilized as heterogeneous catalysts for the hydrolytic cleavage of bis(p-nitrophenyl) phosphate (BNPP).

A series of MOF/Ce-based nanozymes with dual enzyme-like activity disrupting biofilms and hindering recolonization of bacteria

Notorious bacterial biofilms are becoming severe threats to public health worldwide. As the important component in biofilm extracellular polymeric substances (EPS), extracellular DNA (eDNA) has been manifested to connect different EPS components and bacteria together, leading biofilms hard to eliminate. Herein a series of MOF/Ce-based nanozymes with deoxyribonuclease (DNase) and peroxidase mimetic activities have been designed and synthesized for combating biofilms. The cerium (IV) complexes (DNase mimics) are capable of hydrolyzing eDNA and disrupting established biofilms, while the MOF with peroxidase-like activity can kill bacteria exposed in dispersed biofilms in the presence of H₂O₂. This can avoid the recolonization of bacteria and recurrence of biofilms. Given the fact that single-modal antibacterial agent is difficult to drastically eradicate biofilms, the marriage of two kinds of nanozymes is a rational strategy to acquire enhanced performance in combating biofilms. Besides, the utilization of nanozymes circumvents drawbacks of natural enzymes which are costly and vulnerable. Further studies have demonstrated that this kind of artificial enzyme with dual enzyme-mimetic activities can penetrate the biofilms, and inhibit bacterial biofilm formation intensively. Consistently, in vivo anti-biofilm application in treating subcutaneous abscess exhibits commendable wound healing and admirable bactericidal effect. To the best of our knowledge, it is the first time to devise an integrated nanozyme based on the peroxidase-like activity of MOF to eliminate biofilms and kill bacteria on site. This work may promote the application of MOF in the antibacterial field.

First synthesis of orthogonally 1,7-diprotected cyclens

Six novel orthogonally 1,7-heterodiprotected cyclen derivatives have been prepared through an efficient and chromatography-free procedure.

Substrate-Induced Self-Assembly of Cooperative Catalysts

Dissipative self-assembly processes in nature rely on chemical fuels that activate proteins for assembly through the formation of a noncovalent complex. The catalytic activity of the assemblies causes fuel degradation, resulting in the formation of an assembly in a high-energy, out-of-equilibrium state. Herein, we apply this concept to a synthetic system and demonstrate that a substrate can induce the formation of vesicular assemblies, which act as cooperative catalysts for cleavage of the same substrate.

Substrate-Induced Self-Assembly of Cooperative Catalysts

Dissipative self-assembly processes in nature rely on chemical fuels that activate proteins for assembly through the formation of a noncovalent complex. The catalytic activity of the assemblies causes fuel degradation, resulting in the formation of an assembly in a high-energy, out-of-equilibrium state. Herein, we apply this concept to a synthetic system and demonstrate that a substrate can induce the formation of vesicular assemblies, which act as cooperative catalysts for cleavage of the same substrate.

Metal complexes promoting catalytic cleavage of nucleic acids-biochemical tools and therapeutics

The development of metal complexes that promote degradation of nucleic acids has garnered significant interest as a result of their broad range of potential application. This review focuses on recent progress in the design and synthesis of metal complexes as artificial nucleases that promote either hydrolytic or oxidative cleavage of nucleic acids. Illustrative examples demonstrate the versatility of artificial nucleases for in vitro applications as molecular tools to address biochemical problems, as well as their potential use as therapeutic agents. We also address future challenges for improvement and avenues for further investigation.

Lipidic Mesophases as Novel Nanoreactor Scaffolds for Organocatalysts: Heterogeneously Catalyzed Asymmetric Aldol Reactions in Confined Water

The unique molecular architecture of lipidic cubic phases (LCPs) and their cubosome dispersions comprise a well-defined, curved bilayer that spans the entire three-dimensional (3-D) material space, encompassing a network of two periodic, curved, and nonintersecting 3-D aqueous channels. The ensuing large lipid/water interfacial area makes these biomaterials an interesting matrix for the lateral immobilization of organocatalysts to catalyze organic reactions in confined water. Herein, we report for the first time the design, synthesis, assembly, and characterization of catalytically active LCPs and cubosomes and demonstrate their applicability as self-assembled, biomimetic, and recyclable nanoreactor scaffolds. Small-angle X-ray scattering, cryo-transmission electron microscopy, and dynamic light scattering were applied for the characterization of the mesophases. These mesophases can be recycled and enable efficient catalytic activity as well as modulation of the diastereo- and enantioselectivity for the aldol reaction of several benzaldehyde derivatives and cyclohexanone in water.

Polyvalent Catalysts Operating on Polyvalent Substrates: A Model for Surface-Controlled Reactivity

Unusually fast rates of nucleophilic catalysis of hydrazone ligation were observed when polyvalent anthranilic acid catalysts operating on polyvalent aldehyde substrates were used with PAMAM dendrimers as the common platform. When presented in this way, the catalyst has a strong accelerating effect at concentrations 40-400 times lower than those required for similar monovalent catalysts and displays unique kinetic parameters. We attribute these properties to polyvalent engagement between the dendrimer surface groups, and a potential "rolling" effect leading to fast interparticle kinetic turnover. The phenomenon is sensitive to the density of functional groups on each dendrimer, and insensitive to factors that promote or inhibit nonspecific particle aggregation. These findings constitute a rare experimental example of an underappreciated phenomenon in biological and chemical systems that are organized on interacting surfaces.

Hydrolytic Metallo-Nanozymes: From Micelles and Vesicles to Gold Nanoparticles

Although the term nanozymes was coined by us in 2004 to highlight the enzyme-like properties of gold nanoparticles passivated with a monolayer of Zn(II)-complexes in the cleavage of phosphate diesters, systems resembling those metallo-nanoparticles, like micelles and vesicles, have been the subject of investigation since the mid-eighties of the last century. This paper reviews what has been done in the field and compares the different nanosystems highlighting the source of catalysis and frequent misconceptions found in the literature.

A Multinuclear Metal Complex Based DNase-Mimetic Artificial Enzyme: Matrix Cleavage for Combating Bacterial Biofilms

Extracellular DNA (eDNA) is an essential structural component during biofilm formation, including initial bacterial adhesion, subsequent development, and final maturation. Herein, the construction of a DNase-mimetic artificial enzyme (DMAE) for anti-biofilm applications is described. By confining passivated gold nanoparticles with multiple cerium(IV) complexes on the surface of colloidal magnetic Fe3 O4  /SiO2 core/shell particles, a robust and recoverable artificial enzyme with DNase-like activity was obtained, which exhibited high cleavage ability towards both model substrates and eDNA. Compared to the high environmental sensitivity of natural DNase in anti-biofilm applications, DMAE exhibited a much better operational stability and easier recoverability. When DMAE was coated on substratum surfaces, biofilm formation was inhibited for prolonged periods of time, and the DMAE excelled in the dispersion of established biofilms of various ages. Finally, the presence of DMAE remarkably potentiated the efficiency of traditional antibiotics to kill biofilm-encased bacteria and eradiate biofilms.

Kemp Elimination in Cationic Micelles: Designed Enzyme-Like Rates Achieved through the Addition of Long-Chain Bases

The Kemp elimination is prototypical reaction used to study proton abstraction from carbon. Several hydrophobic systems are known to accelerate this reaction, including two classes of computationally-designed enzymes. However, it is unclear whether these computationally-designed enzymes establish specific interactions with their substrates, as natural enzymes do, or if most of the rate acceleration is due to the hydrophobicity of the substrate. We used a simple system composed of cationic micelles and a long chain base (such as lauryl phosphate or lauric acid) to measure the rate acceleration for the Kemp elimination. Remarkably, we found that this simple system can accelerate the reaction by 4 orders of magnitude, approaching the rates of more complex designed systems. Use of different substrates suggests that the reaction takes place at the interface between the micellar head and water (the Stern layer) with the long-chain base embedded in the micelle and the substrate in the aqueous solution. Thus, we suggest that significant rate accelerations can be achieved regardless of the precise positioning of substrates. Because natural enzymes use specific interactions to position their substrates, we propose that acceleration of the Kemp elimination is not a suitable benchmark for the success of the design process, and we suggest that more complex reactions should be used.

Significantly enhanced proteolytic activity of cyclen complexes by monoalkylation

The activity of Cu(ii) and Co(iii) cyclen complexes in the cleavage of proteins was remarkably improved by introducing long alkyl chains thus generating efficient proteolytic amphiphilic metal complexes.