Enzyme-catalyzed Polymerization Research Articles

ROS-responsive core crosslinked micelles by combination of enzymatic polymerization and thiol-ene click chemistry for anticancer drug delivery

The reactive oxygen species (ROS) responsive amphiphilic poly(ethylene glycol)-b-poly(thioketal) (mPEG-b-PTK) copolymer was synthesized by enzyme-catalyzed polymerization for the first time. Core crosslinked (CCL) micelles were prepared via thiol-ene click reaction between the double bond of the side chain of mPEG-b-PTK and the thiol group of pentaerythritol tetrakis (3-mercaptopropionate) as a crosslinker under UV light. The success of crosslinking was verified by NMR and IR. CCL micelles showed better stability in stability against dilution and storage stability experiments compared with the uncrosslinked (UCL) micelles. The ROS-responsiveness of CCL micelles was characterized by DLS, TEM, NMR, AFM and SEM. In vitro release studies, CCL micelles encapsulating doxorubicin (DOX) showed a faster release rate of nearly 100% within 32 h in PBS containing 5 mM H2O2 compared to the control without H2O2. Cytotoxicity test demonstrated good biocompatibility of CCL micelles and low toxicity with cell viability above 82% and 86% in HeLa cells and HUVEC cells, respectively. And CCL DOX-loaded micelles exhibited great anticancer activity with IC50 value about 4.8 mg/L for Hela cells. Finally, flow cytometry and confocal laser scanning microscope (CLSM) showed that DOX-loaded micelles had excellent internalization efficiency in HeLa cells. The obtained ROS-responsive CCL micelles held promise for anticancer drug delivery.

Synthesis, Modification and Application of Polylactic Acid

The massive use of petroleum-based plastics has caused tremendous damage to the world's environment, so it has become increasingly urgent to develop biodegradable materials represented like polylactic acid (PLA). PLA is a non-polluting, completely degradable and renewable polymer material with high strength, high modulus and good biocompatibility. However, the disadvantages of conventional PLA, such as poor heat resistance and limited flexibility, limit its application. Therefore, its modification is needed. This article summarizes the structure and properties of PLA and describes the synthesis methods based on direct polymerization, ring-opening polymerization and enzyme-catalyzed polymerization. The article also reviews the methods of PLA modification, including physical modification by adding fibrous materials, nucleating agents, and compound modification, and chemical methods such as copolymerization and cross-graft modification. Moreover, the article presents the applications of PLA in packaging and medical materials. At the end of this article, future research and development directions of PLA are discussed.

Exploiting Enzyme in the Polymer Synthesis for a Remarkable Increase in Thermal Conductivity.

The interest in polymers with high thermal conductivity increased much because of their inherent properties such as low density, low cost, flexibility, and good chemical resistance. However, it is challenging to engineer plastics with good heat transfer characteristics, processability, and required strength. Improving the degree of the chain alignment and forming a continuous thermal conduction network is expected to enhance thermal conductivity. This research aimed to develop polymers with a high thermal conductivity that can be interesting for several applications. Two polymers, namely poly(benzofuran-co-arylacetic acid) and poly(tartronic-co-glycolic acid), with high thermal conductivity containing microscopically ordered structures were prepared by performing enzyme-catalyzed (Novozyme-435) polymerization of the corresponding α-hydroxy acids 4-hydroxymandelic acid and tartronic acid, respectively. A comparison between the polymer's structure and heat transfer obtained by mere thermal polymerization before and enzyme-catalyzed polymerization will now be discussed, revealing a dramatic increase in thermal conductivity in the latter case. The polymer structures were investigated by FTIR spectroscopy, nuclear magnetic resonance (NMR) spectroscopy in liquid- and solid-state (ss-NMR), and powder X-ray diffraction. The thermal conductivity and diffusivity were measured using the transient plane source technique.

Effects of the modification of bacterial cellulose as a template for the in situ enzyme-catalyzed polymerization of catechol

In this study, we investigated the effects of the modification of bacterial cellulose used as a template on the in situ polymerization of catechol by laccase. The bacterial cellulose was modified by sulfonation and the entrapment of carboxymethyl cellulose. The catechol polymerization was optimized at a pH of 5.5, catechol concentration of 50 mM, and synthesis time of 24 h. After the in situ polymerization, conductive and colored bacterial cellulose composites were obtained. The bacterial cellulose composites containing oligomers/polymers were analyzed using Fourier-transform infrared spectroscopy, scanning electron microscopy, and color strength measurements, and the conductivity of the bacterial cellulose composites was evaluated using a four-probe method. The results revealed that the modification of bacterial cellulose as a template for catechol oxidation resulted in the production of fibers with enhanced coloration and conductive properties owing to the presence of the enzymatically-obtained polymers. The results suggest the promising potential of both sulfonated bacterial cellulose and carboxymethyl cellulose-bacterial cellulose as templates for the formation of other functional polymers and composite materials.

Enzyme-catalyzed synthesis of 4-methylcatechol oligomer and preliminary evaluations as stabilizing agent in polypropylene

Abstract In the present work, 4-methylcatechol oligomer has been prepared by using enzyme-catalyzed polymerization in water and preliminary evaluations as stabilizing agent in polypropylene (PP) was performed. In comparison with intrinsic PP, the oxidation onset temperature of the 4-methylcatechol oligomer/PP composite increased by 66°C, and the oxidation induction time increased by 40 min. In addition, the mixing of a 4-methylcatechol oligomer with PP (i.e., in the formation of a 4-methylcatechol oligomer/PP composite) did significantly enhance the long-term stability of PP in a thermal oxidative environment. Moreover, the tensile strength of this composite did not significantly decrease after aging for 800 h in an air atmosphere at 120°C. These results show that the addition of a 4-methylcatechol oligomer will markedly delay the aging and degradation of PP materials, even under extreme conditions. Thus, an enzyme-catalyzed polymerization of phenol compounds may provide a new avenue toward the preparation of novel antioxidants.

Enzyme-Catalyzed Polymerization of Kraft Lignin from Eucalyptus globulus: Comparison of Bacterial and Fungal Laccases Efficacy.

Kraft lignin, a side-stream from the pulp and paper industry, can be modified by laccases for the synthesis of high added-value products. This work aims to study different laccase sources, including a bacterial laccase from Streptomyces ipomoeae (SiLA) and a fungal laccase from Myceliophthora thermophila (MtL), for kraft lignin polymerization. To study the influence of some variables in these processes, a central composite design (CCD) with two continuous variables (enzyme concentration and reaction time) and three levels for each variable was used. The prediction of the behavior of the output variables (phenolic content and molecular weight of lignins) were modelled by means of response surface methodology (RSM). Moreover, characterization of lignins was performed by Fourier-transform infrared (FTIR) spectroscopy and different nuclear magnetic resonance (NMR) spectroscopy techniques. In addition, antioxidant activity was also analyzed. Results showed that lignin polymerization (referring to polymerization as lower phenolic content and higher molecular weight) occurred by the action of both laccases. The enzyme concentration was the most influential variable in the lignin polymerization reaction within the range studied for SiLA laccase, while the most influential variable for MtL laccase was the reaction time. FTIR and NMR characterization analysis corroborated lignin polymerization results obtained from the RSM.

Recent Advances in the Enzymatic Synthesis of Polyester

Polyester is a kind of polymer composed of ester bond-linked polybasic acids and polyol. This type of polymer has a wide range of applications in various industries, such as automotive, furniture, coatings, packaging, and biomedical. The traditional process of synthesizing polyester mainly uses metal catalyst polymerization under high-temperature. This condition may have problems with metal residue and undesired side reactions. As an alternative, enzyme-catalyzed polymerization is evolving rapidly due to the metal-free residue, satisfactory biocompatibility, and mild reaction conditions. This article presented the reaction modes of enzyme-catalyzed ring-opening polymerization and enzyme-catalyzed polycondensation and their combinations, respectively. In addition, the article also summarized how lipase-catalyzed the polymerization of polyester, which includes (i) the distinctive features of lipase, (ii) the lipase-catalyzed polymerization and its mechanism, and (iii) the lipase stability under organic solvent and high-temperature conditions. In addition, this article also focused on the advantages and disadvantages of enzyme-catalyzed polyester synthesis under different solvent systems, including organic solvent systems, solvent-free systems, and green solvent systems. The challenges of enzyme optimization and process equipment innovation for further industrialization of enzyme-catalyzed polyester synthesis were also discussed in this article.

Enzymatic synthesis, post-polymerization modification and cross-linking of functionalized poly(β-thioether ester) with pendant vinyl group

Vinyl-functionalized poly(β-thioether ester) (PVTE) was synthesized by enzyme-catalyzed polymerization using immobilized lipase B from Candida antarctica (CALB) for the first time. Four different functionalized monomers were prepared and three polymerization strategies including polycondensation (PC), ring-opening polymerization (ROP), and ring-opening and condensation copolymerization (ROCCP) were investigated. The influences of reaction conditions such as polymerization temperature, time, and monomer ratio on the molecular weight of functionalized poly(β-thioether ester)s were also studied. Both the homopolymer and copolymers were characterized by NMR, SEC, TGA and DSC. Moreover, these poly(β-thioether ester)s containing pendant double bonds toward postfunctionalization were demonstrated by photoinitiated thiol-ene click chemistry and Michael addition reaction, providing a way to cross-linked polyester gels.

Enzyme-Catalyzed Polymerization Process: A Novel Approach to the Preparation of Polyaniline Colloidal Dispersions with an Immunomodulatory Effect.

A green, nature-friendly synthesis of polyaniline colloidal particles based on enzyme-assisted oxidation of aniline with horseradish peroxidase and chitosan or poly(vinyl alcohol) as steric stabilizers was successfully employed. Physicochemical characterization revealed formation of particles containing the polyaniline emeraldine salt and demonstrated only a minor effect of polymer stabilizers on particle morphology. All tested colloidal particles showed in vitro antioxidation activity determined via scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. In vitro, they were able to reduce oxidative stress and inhibit the production of reactive oxygen species by neutrophils and inflammatory cytokines by macrophages. The anti-inflammatory effect observed was related to their antioxidant activity, especially in the case of neutrophils. The particles can thus be especially advantageous as active components of biomaterials modulating the early stages of inflammation. In addition to the immunomodulatory effect, the presence of intrinsically conducting polyaniline can impart cell-instructive properties to the particles. The approach to particle synthesis that we employed─an original one using environmentally friendly and biocompatible horseradish peroxidase─represents a smart way of preparing conducting particles with unique properties, which can be further modified by the stabilizers used.

Production of antimicrobial powders of guaiacol oligomers by a laccase-catalyzed synthesis reaction

Guaiacol oligomers were synthesized by enzyme-catalyzed polymerization with laccase as the catalyst. The polymerization procedure in aqueous media was followed by UV–vis spectra. The oligomers were characterized by NMR and MALDI-TOF spectra. The UV–vis spectra observation showed a new peak formed in the range of 380−530 nm indicating that new substances formed. The NMR results indicated that phenolic hydroxyl participated in the polymerization. The MALDI-TOF spectra revealed the weight average polymerization degree of guaiacol oligomers is 10 and the mass of the repeating unit is 122. The thermal stability was studied by TGA/DSC analysis. Guaiacol oligomers were more thermally stable than guaiacol, which can be ascribed to the long π-conjugated chains. Antioxidant behavior based on ABTS+ radical showed a concentration-dependent activity and reached a plateau at 800 μg/mL. The prepared guaiacol oligomers displayed antimicrobial activity against Staphylococcus aureus and Escherichia coli, in which the inhibition percentage is up to 99 %.

Fluorogenic Biosensors Constructed via Aggregation-induced Emission Based on Enzyme-catalyzed Coupling Reactions for Detection of Hydrogen Peroxide.

Hydrogen peroxide (H2O2) is a main reactive oxygen by-product produced in the metabolism of organisms and a common biomarker of oxidative stress. Aggregation-induced emission (AIE) probes for H2O2 have been proposed. Such AIEgens mostly use benzeneboronic acid as a recognition group. Recently, a strategy involving enzyme-catalyzed polymerization of AIE compounds shows great potential in AIEgens design. We herein modify the AIE motif, tetraphenylethene (TPE) with o-phenylenediamine (TPE-TAF), which can be oxidated by H2O2 in HRP to form an intramolecular phenazine structure. Compared with a similar approach, the proposed strategy is simple and the TPE-TAF showed a sensitive "turn-on" fluorescence with H2O2. The detection limit (LOD) is 3.39 μM and the probe is highly specific against H2O2. We further verified the reaction mechanism of the enzyme-catalyzed coupling reaction. The probe is a promising candidate as a stable and safe fluorescent substrate in H2O2 sensing.

A Strategy Based on the Enzyme-Catalyzed Polymerization Reaction of Asp-Phe-Tyr Tripeptide for Cancer Immunotherapy.

Immunotherapy has provided a promising strategy for the treatment of cancers. However, even in tumors with high antigen burdens, the systemic inhibition of the antigen presentation still greatly restricts the application of immunotherapy. Here, we construct a tumor protein-engineering system based on the functional tripeptide, Asp-Phe-Tyr (DFY), which can automatically collect and deliver immunogenetic tumor proteins from targeted cells to immune cells. Through a tyrosinase-catalyzed polymerization, the DFY tripeptide selectively accumulates in tyrosinase high-expressed melanoma cells. Then quinone-rich intermediates are covalently linked with tumor-specific proteins by Michael addition and form tumor protein-carried microfibers that could be engulfed by antigen-presenting cells and exhibited tumor antigenic properties for boosting immune effect. In melanoma cells with deficient antigen presentation, this system can successfully enrich and transport tumor antigen-containing proteins to immune cells. Furthermore, in the in vivo study on murine melanoma, the transdermal delivery of the DFY tripeptide suppressed the tumor growth and the postsurgery recurrence. Our findings provide an avenue for the regulation of the immune system on an organism by taking advantage of certain polymerization reactions by virtue of chemical biology.

Synthesis and Biopharmaceutical Applications of Sugar-Based Polymers: New Advances and Future Prospects.

The rapid rise in research interest in carbohydrate-based polymers is undoubtedly due to the nontoxic nature of such materials in an in vivo environment and the versatile roles that the polymers can play in cellular functions. Such polymers have served as therapeutic tools for drug delivery, including antigens, proteins, and genes, as well as diagnostic devices. Our focus in the first half of this Review is on synthetic methods based on ring-opening polymerization and enzyme-catalyzed polymerization, along with controlled radical polymerization. In the second half of this Review, sugar-based polymers are discussed on the basis of their remarkable success in competitive receptor binding, as multifunctional nanocarriers of targeting inhibitors for cancer treatment, in genome-editing delivery, in immunotherapy based on endogenous antibody recruitment, and in treatment of respiratory diseases, including influenza A. Particular emphasis is put on the synthesis and biopharmaceutical applications of sugar-based polymers published in the most recent 5 years. A noticeable attribute of carbohydrate-based polymers is that the sugar-receptor interactions can be facilitated by the cooperative effect of multiple sugar units. Their diversified topology and structures will drive the development of new synthetic strategies and bring about important applications, including coronavirus-related drug therapy.

Core-Shell Structured Phenolic Polymer@TiO2 Nanosphere with Enhanced Visible-Light Photocatalytic Efficiency.

Core–shell structured TiO2 is a promising solution to promote the photocatalytic effectiveness in visible light. Compared to metal or semiconductor materials, polymers are rarely used as the core materials for fabricating core–shell TiO2 materials. A novel core–shell structured polymer@TiO2 was developed by using phenolic polymer (PP) colloid nanoparticles as the core material. The PP nanoparticles were synthesized by an enzyme-catalyzed polymerization in water. A subsequent sol–gel and hydrothermal reaction was utilized to cover the TiO2 shell on the surfaces of PP particles. The thickness of the TiO2 shell was controlled by the amount of TiO2 precursor. The covalent connection between PP and TiO2 was established after the hydrothermal reaction. The core–shell structure allowed the absorption spectra of PP@TiO2 to extend to the visible-light region. Under visible-light irradiation, the core–shell nanosphere displayed enhanced photocatalytic efficiency for rhodamine B degradation and good recycle stability. The interfacial C–O–Ti bonds and the π-conjugated structures in the PP@TiO2 nanosphere played a key role in the quick transfer of the excited electrons between PP and TiO2, which greatly improved the photocatalytic efficiency in visible light.

An aptasensor based on electrosynthesized conducting polymers, Cu2O–carbon dots and biosynthesized gold nanoparticles, for monitoring carcinoembryonic antigen

Current work proposes an inimitable composite, with great electrical conductivity and quite enhanced surface area, (including conducting polymers (poly (cathechol)), Cu2O–carbon dots and green synthesized gold nanoparticles) for detecting acute carcinoembryonic antigen. At current work, the electropolymerization was offered instead of enzyme-catalyzed polymerization of poly (catechol). Four cost-effective electrochemical techniques (Differential Pulse Voltammetry, Electrochemical Impedance Spectroscopy, Cyclic Voltammetry and Crono amperometry) were engaged to investigate aptasensors construction, immobilization, hybridization, sensitivity, selectivity, repeatability, long-term stability and real PCR sample detections. According to the data, the values of Ipeak is linearly related to the logarithm of the concentrations of carcinoembryonic antigen in the range from 1.0 pg mL-1 to 0.001 g mL-1, with a detection limit of 0.19 pg mL-1 for the target antigen (carcinoembryonic antigen). Keywords: conducting polymer, carbon quantum dots, green synthesize, elctrosynthesize, screen-printed electrode, carcinoembryonic antigen. Keywords: conducting polymer, carbon quantum dots, green synthesize, elctrosynthesize, screen-printed electrode, carcinoembryonic antigen

Soybean Peroxidase-Induced Treatment of Dye-Derived Arylamines in Water

This research investigated the enzyme-catalyzed oxidative polymerization and precipitation/co-precipitation of the anilino compounds, p-cresidine (2-methoxy-5-methylaniline), and 4,4′-oxydianiline (ODA) suspected to be human carcinogens by the U.S. Environmental Protection Agency, as a means of treating industrial wastewater containing these pollutants. p-Cresidine is a synthetic chemical intermediate for azo dyes and pigments in the food and textile industries whereas ODA is used in the production of polyimide and poly(ester)imide resins in North America. A potentially inexpensive enzyme extracted from the soybean seed coat, soybean peroxidase (SBP), which is widely available from the agricultural commodity, was used to treat both these compounds. The optimum operating conditions such as pH, hydrogen peroxide-to-substrate concentration ratio, and the minimum SBP concentration required to achieve at least 95% SBP-catalyzed conversion of these pollutants in synthetic wastewaters were determined. Electrospray ionization mass spectrometry, employed for preliminary product determination after enzymatic conversion of the substrates, revealed the formation of azo dimers in the precipitates. A pro-forma cost analysis is presented showing the feasibility of commercialization of enzymatic treatment as an alternative, or as an adjunct, to conventional treatment methods.

Intracellular construction of topology-controlled polypeptide nanostructures with diverse biological functions

Topological structures of bio-architectonics and bio-interfaces play major roles in maintaining the normal functions of organs, tissues, extracellular matrix, and cells. In-depth understanding of natural self-assembly mechanisms and mimicking functional structures provide us opportunities to artificially control the natural assemblies and their biofunctions. Here, we report an intracellular enzyme-catalyzed polymerization approach for efficient synthesis of polypeptides and in situ construction of topology-controlled nanostructures. We reveal that the phase behavior and topological structure of polypeptides are encoded in monomeric peptide sequences. Next, we elucidate the relationship between polymerization dynamics and their temperature-dependent topological transition in biological conditions. Importantly, the linearly grown elastin-like polypeptides are biocompatible and aggregate into nanoparticles that exhibit significant molecular accumulation and retention effects. However, 3D gel-like structures with thermo-induced multi-directional traction interfere with cellular fates. These findings allow us to exploit new nanomaterials in living subjects for biomedical applications.

Enzyme-Catalyzed Synthesis of Water-Soluble Conjugated Poly[2-(3-thienyl)-Ethoxy-4-Butylsulfonate

An environmentally friendly water-soluble conjugated polythiophene poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] (PTEBS) has been found to be effective for making hybrid solar cells. In this work, we first report the enzyme-catalyzed polymerization of (3-thienyl)-ethoxy-4-butylsulfonate (TEBS) using horseradish peroxidase (HRP) enzyme as a catalyst and hydrogen peroxide (H2O2) as an oxidant in an aqueous buffer. This enzyme-catalyzed polymerization is a “green synthesis process” for the synthesis of water-soluble conjugated PTEBS, the benefits of which include a simple setting, high yields, and an environmentally friendly route. Fourier transform infrared spectra (FTIR) and UV–Vis absorption spectra confirm the successful enzyme-catalyzed polymerization of TEBS. The thermo gravimetric (TG) data show the obtained PTEBS is stable over a fairly high range of temperatures. The present PTEBS has a good solubility in water and ethanol, and photoluminescence quenching of PTEBS/titanium dioxide (TiO2) composite implies that the excitons dissociate and separate successfully at the interface of PTEBS and TiO2, which help to build solar cells using green processing methods.

Functionalized Celluloses with Regular Substitution Pattern by Glycosynthase-Catalyzed Polymerization.

Control of the monomer sequence in polymers is extraordinarily difficult by chemical synthesis, though Nature routinely exerts such control, including in the biosynthesis of polysaccharides. This inability has prevented us from being able to match the exquisite structure-activity control exhibited in biosynthesis of bioactive natural polysaccharides. We here address a powerful approach, whereby enzyme-catalyzed polymerization of properly modified building blocks is introduced as a simple route affording polysaccharides with controlled sequence and functionalization pattern. Targeting cellulose as a versatile scaffold for novel biomaterials, we describe the preparation of a perfectly alternating polysaccharide with repeat unit 6'-azido-6'-deoxycellobiose by a glycosynthase-catalyzed polymerization using the Humicola insolens cellulase Cel7B E197A mutant, and its further functionalization to give novel modified cellulose derivatives with a regular substitution pattern.

Enzymatic synthesis of polyguaiacol and its thermal antioxidant behavior in polypropylene

Polyguaiacol was successfully synthesized by enzyme-catalyzed polymerization in an aqueous micelle system with horseradish peroxidase (HRP) as the catalyst. As-synthesized polyguaiacol was characterized by infrared spectrometry and gel permeation chromatography, and its thermal stability was evaluated by thermogravimetric analysis. Besides, the thermal antioxidant behavior of the as-synthesized phenolic polymer as an antioxidant in polypropylene was evaluated by differential scanning calorimetry and accelerated aging test, and the apparent activation energies of thermal decomposition of polypropylene (PP) were calculated by Friedman method. Results show that the as-synthesized polyguaiacol as an antioxidant is able to significantly increase the oxidation induction time of virgin PP, and it exhibits better antioxidative performance than corresponding monomer. Moreover, polyguaiacol, the as-synthesized phenolic polymer, exhibits good resistance against aging of polypropylene.