Search Results (27)

Over the past three decades, organic reactions catalyzed by lipase have been extensively studied. To overcome the drawbacks of free enzymes and develop new and sustainable biocatalysts, various insoluble forms of lipases were examined. Especially interesting are lipases immobilized on silica nanoparticles (SiNPs) due to their promising unique and advantageous physicochemical properties. Therefore, the present paper presents an overview of different organic functionalization methods of SiNP surfaces to create a more favorable microenvironment for lipase molecules. Given the high commercial value of lipases in biotechnological applications, the second part of this paper highlights the key industrial sectors utilizing these nanobiocatalysts. This review discusses the key industrial applications of silica-based lipase nanobiocatalysts, including biodiesel production, flavor ester synthesis, and pharmaceutical applications such as racemization. Special attention is given to emerging technologies, particularly the use of immobilized lipases in polymer biodegradation and polymerization reactions. These advances have paved the way for innovative solutions, such as self-degrading bioplastics, which hold significant promise for sustainable materials and environmental protection. This comprehensive overview underscores the transformative potential of lipase–SiNP nanobiocatalysts in both industrial and environmental contexts. Full article

One way to enhance the flow properties of packed bed reactors, including efficient mass transfer and high catalyst conversion rates, is the use of 3D printing. By creating optimized structures that prevent channeling and high pressure drops, it is possible to achieve the desired target. Nevertheless, additively manufactured structures most often possess a limited surface-area-to-volume-ratio, especially as porous printed structures are not standardized yet. One way to achieve surface-enhanced 3D-printed structures is surface modification to introduce surface-initiated polymers. In addition, when stimuli-sensitive polymers are chosen, autonomous process control is prospective. The current publication deals with the application of surface-induced polymerization on 3D-printed structures with the subsequent application as an enzyme carrier. Surface-induced polymerization can easily increase the number of enzymes by a factor of six compared to the non-modified 3D-printed structure. In addition, the swelling behavior of polyacrylic acid is proven, even with immobilized enzymes, enabling smart reaction control. The maximum activity of Esterase 2 (Est2) from Alicyclobacillus acidocaldarius per g carrier, determined after 2 h of polymer synthesis, is 0.61 U/g_support. Furthermore, universal applicability is shown in aqueous and organic systems, applying an Est2 and Candida antarctica lipase B (CalB) catalyzed reaction and leaving space for improvement due to compatibility of the functionalization process and the here chosen organic solvent. Overall, no enzyme leaching is detectable, and process stability for at least five subsequent batches is ensured. Full article

Polylactic acid (PLA) is the main biobased plastic manufactured on an industrial scale. This polymer is synthetized by chemical methods, and there is a strong demand for the implementation of clean technologies. This work focuses on the microbial fermentation of agro-industrial waste rich in starch for the production of lactic acid (LA) in a consolidated bioprocess, followed by the enzymatic synthesis of PLA. Lactic acid bacteria (LAB) and the fungus Rhizopus oryzae were evaluated as natural LA producers in pure cultures or in fungal–lactobacteria co-cultures formed by an LAB and a fungus selected for its metabolic capacity to degrade starch and to form consortia with LAB. Microbial interaction was analyzed by scanning electron microscopy and biofilm production was quantified. The results show that the fungus Talaromyces amestolkiae and Lactiplantibacillus plantarum M9MG6-B2 establish a cooperative relationship to exploit the sugars from polysaccharides provided as carbon sources. Addition of the quorum sensing molecule dodecanol induced LA metabolism of the consortium and resulted in improved cooperation, producing 99% of the maximum theoretical yield of LA production from glucose and 65% from starch. Finally, l-PLA oligomers (up to 19-LA units) and polymers (greater than 5 kDa) were synthetized by LA polycondensation and enzymatic ring-opening polymerization catalyzed by the non-commercial lipase OPEr, naturally produced by the fungus Ophiostoma piceae. Full article

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. Full article

Cyclodextrins have previously been proven to be active in the catalysis of cyclic ester ring-opening reactions, hypothetically in a similar way to lipase-catalyzed reactions. However, the way they act remains unclear. Here, we focus on β-cyclodextrin’s involvement in the synthesis and characterization of β-cyclodextrin-oligocaprolactone (CDCL) products obtained via the organo-catalyzed ring-opening of ε-caprolactone. Previously, bulk or supercritical carbon dioxide polymerizations has led to inhomogeneous products. Our approach consists of solution polymerization (dimethyl sulfoxide and dimethylformamide) to obtain homogeneous CDCL derivatives with four monomer units on average. Oligomerization kinetics, performed by a matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) optimized method in tandem with ¹H NMR, revealed that monomer conversion occurs in two stages: first, the monomer is rapidly attached to the secondary OH groups of β-cyclodextrin and, secondly, the monomer conversion is slower with attachment to the primary OH groups. MALDI MS was further employed for the measurement of the ring-opening kinetics to establish the influence of the solvents as well as the effect of organocatalysts (4-dimethylaminopyridine and (–)-sparteine). Additionally, the mass spectrometry structural evaluation was further enhanced by fragmentation studies which confirmed the attachment of oligoesters to the cyclodextrin and the cleavage of dimethylformamide amide bonds during the ring-opening process. Full article

Amphiphilic copolymers are appealing materials because of their interesting architecture and tunable properties. In view of their application in the biomedical field, the preparation of these materials should avoid the use of toxic compounds as catalysts. Therefore, enzymatic catalysis is a suitable alternative to common synthetic routes. Pentablock copolymers (CUC) were synthesized with high yields by ring-opening polymerization of ε-caprolactone (ε-CL) initiated by Pluronic (EPE) and catalyzed by Candida antarctica lipase B enzyme. The variables to study the structure–property relationship were EPEs’ molecular weight and molar ratios between ε-CL monomer and EPE macro-initiator (M/In). The obtained copolymers were chemically characterized, the molecular weight determined, and morphologies evaluated. The results suggest an interaction between the reaction time and M/In variables. There was a correlation between the differential scanning calorimetry data with those of X-ray diffraction (WAXD). The length of the central block of CUC copolymers may have an important role in the crystal formation. WAXD analyses indicated that a micro-phase separation takes place in all the prepared copolymers. Preliminary cytotoxicity experiments on the extracts of the polymer confirmed that these materials are nontoxic. Full article

Here, we report a new two-step enzymatic polymerization strategy for the synthesis of poly(octamethylene suberate) (POS) using an immobilized Pseudozyma antarctica lipase B (IMM-PBLI). The strategy overcomes the lack of enzymatic POS synthesis in solvent-free systems and increases the final polymer molecular weight. In the first step, the direct polycondensation of suberic acid and 1,8-octanediol was catalyzed by IMM-PBLI at 45 °C, leading to the production of prepolymers with molecular weights (MWs) of 2800, 3400, and 4900 g mol⁻¹ after 8 h in miniemulsion, water, and an organic solvent (cyclohexane: tetrahydrofuran 5:1 v/v), respectively. In the second polymerization step, wet prepolymers were incubated at 60 or 80 °C, at atmospheric pressure, in the presence of IMM-PBLI, and without stirring. The final POS polymers showed a significant increase in MW to 5000, 5800, and 19,800 g mol⁻¹ (previously synthesized in miniemulsion, water, or organic solvent, respectively). FTIR analysis of the final polymers confirmed the successful POS synthesis and a high degree of monomer conversion. This innovative two-step polymerization strategy opens up a new opportunity for implementing greener and more environmentally friendly processes for synthesizing biodegradable polyesters. Full article

Enzymatic synthesis of aromatic biobased polyesters is a recent and rapidly expanding research field. However, the direct lipase-catalyzed synthesis of polyesters from ferulic acid has not yet been reported. In this work, various ferulic-based monomers were considered for their capability to undergo CALB-catalyzed polymerization. After conversion into diesters of different lengths, the CALB-catalyzed polymerization of these monomers with 1,4-butanediol resulted in short oligomers with a DP_n up to 5. Hydrogenation of the double bond resulted in monomers allowing obtaining polyesters of higher molar masses with DP_n up to 58 and M_w up to 33,100 g·mol⁻¹. These polyesters presented good thermal resistance up to 350 °C and T_g up to 7 °C. Reduction of the ferulic-based diesters into diols allowed preserving the double bond and synthesizing polyesters with a DP_n up to 19 and M_w up to 15,500 g·mol⁻¹ and higher T_g (up to 21 °C). Thus, this study has shown that the monomer hydrogenation strategy proved to be the most promising route to achieve ferulic-based polyester chains of high DP_n. This study also demonstrates for the first time that ferulic-based diols allow the synthesis of high T_g polyesters. Therefore, this is an important first step toward the synthesis of competitive biobased aromatic polyesters by enzymatic catalysis. Full article

This work explores for the first time the enzymatic synthesis of poly(butylene-co-ε-caprolactone) (PBSCL) copolyesters in bulk using commercially available monomers (dimethyl succinate (DMS), 1,4-butanediol (BD), and ε-caprolactone (CL)). A preliminary kinetic study was carried out which demonstrated the higher reactivity of DMS over CL in the condensation/ring opening polymerization reaction, catalyzed by Candida antarctica lipase B. PBSCL copolyesters were obtained with high molecular weights and a random microstructure, as determined by ¹³C NMR. They were thermally stable up to 300 °C, with thermal stability increasing with the content of CL in the copolyester. All of them were semicrystalline, with melting temperatures and enthalpies decreasing up to the eutectic point observed at intermediate compositions, and glass transition temperatures decreasing with the content of CL in the copolyester. The use of CALB provided copolyesters free from toxic metallic catalyst, which is very useful if the polymer is intended to be used for biomedical applications. Full article

Biocatalysis has developed in the last decades as a major tool for green polymer synthesis. The particular ability of lipases to catalyze the synthesis of novel polymeric materials has been demonstrated for a large range of substrates. In this work, novel functional oligoesters were synthesized from ε-caprolactone and D,L/L-malic acid by a green and sustainable route, using two commercially available immobilized lipases as catalysts. The reactions were carried out at different molar ratios of the comonomers in organic solvents, but the best results were obtained in solvent-free systems. Linear and cyclic oligomeric products with average molecular weights of about 1500 Da were synthesized, and the formed oligoesters were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The oligoester synthesis was not enantioselective in the studied reaction conditions. The operational stability of both biocatalysts (Novozyme 435 and GF-CalB-IM) was excellent after reutilization in 13 batch reaction cycles. The thermal properties of the reaction products were investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. The presence of polar pendant groups in the structure of these oligomers could widen the possible applications compared to the oligomers of ε-caprolactone or allow the conversion to other functional materials. Full article

Among the various catalysts that can be used for polycondensation reactions, enzymes have been gaining interest for three decades, offering a green and eco-friendly platform towards the sustainable design of renewable polyesters. However, limitations imposed by their delicate nature, render them less addressed. As a case study, we compare herein bulk and solution polycondensation of 1,6-hexanediol and diethyl adipate catalyzed by an immobilized lipase from Candida antarctica. The influence of various parameters including time, temperature, enzyme loading, and vacuum was assessed in the frame of a two-step polymerization with the help of response surface methodology, a statistical technique that investigates relations between input and output variables. Results in solution (diphenyl ether) and bulk conditions showed that a two-hour reaction time was enough to allow adequate oligomer growth for the first step conducted under atmospheric pressure at 100 °C. The number-average molecular weight (M_n) achieved varied between 5000 and 12,000 g·mol⁻¹ after a 24 h reaction and up to 18,500 g∙mol⁻¹ after 48 h. The statistical analysis showed that vacuum was the most influential factor affecting the M_n in diphenyl ether. In sharp contrast, enzyme loading was found to be the most influential parameter in bulk conditions. Recyclability in bulk conditions showed a constant M_n of the polyester over three cycles, while a 17% decrease was noticed in solution. The following work finally introduced a statistical approach that can adequately predict the M_n of poly(hexylene adipate) based on the choice of parameter levels, providing a handy tool in the synthesis of polyesters where the control of molecular weight is of importance. Full article

In recent years, developing potent antioxidants has been a very active area of research. In this context, phenolic compounds have been evaluated for their antioxidant activity. However, the use of phenolic compounds has also been limited by poor antioxidant activity in several in vivo studies. Polymeric phenols have received much attention owing to their potent antioxidant properties and increased stability in aqueous systems. To be truly effective in biological applications, it is important that these polymers be synthesized using benign methods. In this context, enzyme catalyzed synthesis of polymeric phenols has been explored as an environmentally friendly and safer approach. This review summarizes work in enzymatic syntheses of polymers of phenols. Several assays have been developed to determine the antioxidant potency of these polymeric phenols. These assays are discussed in detail along with structure-property relationships. A deeper understanding of factors affecting antioxidant activity would provide an opportunity for the design of versatile, high performing polymers with enhanced antioxidant activity. Full article

The enzymatically synthesized poly (glycerol adipate) (PGA) has demonstrated all the desirable key properties required from a performing biomaterial to be considered a versatile “polymeric-tool” in the broad field of drug delivery. The step-growth polymerization pathway catalyzed by lipase generates a highly functionalizable platform while avoiding tedious steps of protection and deprotection. Synthesis requires only minor purification steps and uses cheap and readily available reagents. The final polymeric material is biodegradable, biocompatible and intrinsically amphiphilic, with a good propensity to self-assemble into nanoparticles (NPs). The free hydroxyl group lends itself to a variety of chemical derivatizations via simple reaction pathways which alter its physico-chemical properties with a possibility to generate an endless number of possible active macromolecules. The present work aims to summarize the available literature about PGA synthesis, architecture alterations, chemical modifications and its application in drug and gene delivery as a versatile carrier. Following on from this, the evolution of the concept of enzymatically-degradable PGA-drug conjugation has been explored, reporting recent examples in the literature. Full article

Following the latest developments, bio-based polyesters, obtained from renewable raw materials, mainly carbohydrates, can be competitive for the fossil-based equivalents in various industries. In particular, the furan containing monomers are valuable alternatives for the synthesis of various new biomaterials, applicable in food additive, pharmaceutical and medical field. The utilization of lipases as biocatalysts for the synthesis of such polymeric compounds can overcome the disadvantages of high temperatures and metal catalysts, used by the chemical route. In this work, the enzymatic synthesis of new copolymers of ε-caprolactone and 5-hydroxymethyl-2-furancarboxylic acid has been investigated, using commercially available immobilized lipases from Candida antarctica B. The reactions were carried out in solvent-less systems, at temperatures up to 80 °C. The structural analysis by MALDI TOF-MS, NMR, and FT-IR spectroscopy confirmed the formation of cyclic and linear oligoesters, with maximal polymerization degree of 24 and narrow molecular weight distribution (dispersity about 1.1). The operational stability of the biocatalyst was explored during several reuses, while thermal analysis (TG and DSC) indicated a lower thermal stability and higher melting point of the new products, compared to the poly(ε-caprolactone) homopolymer. The presence of the heterocyclic structure in the polymeric chain has promoted both the lipase-catalyzed degradation and the microbial degradation. Although, poly(ε-caprolactone) is a valuable biocompatible polymer with important therapeutic applications, some drawbacks such as low hydrophilicity, low melting point, and relatively slow biodegradability impeded its extensive utilization. In this regard the newly synthesized furan-based oligoesters could represent a “green” improvement route. Full article

Glycerol carbonate (GC) is a value-added product originating from the valorization of widely available glycerol (Gly), a side stream from the production of biodiesel. Here we approach the production of this chemical comparing two reactions based on the transesterification of Gly with dimethyl carbonate (DMC) and ethylene carbonate (EC). When using DMC, it was observed that the free enzyme CALB (lipase B from Candida antarctica) gave the best results, whereas Eversa Transform (a genetic modification of Thermomyces lanuginosus lipase) performed better than the rest if EC was the reagent. With the selected catalysts, their immobilized analogous enzymes Novozym 435 and Lypozyme TL IM, respectively, were also tested. Observing that the yields for the reaction with EC were significantly faster, other operating variables were evaluated, resulting the best performance using a closed system, tert-butanol as solvent, a concentration of enzyme Eversa Transform of 3% w/w, a molar excess of EC:Gly of 9:1 and a temperature of 60 °C. Finally, several runs were conducted at different temperatures and molar ratios of EC:Gly, fitting a kinetic model to all experimental data for the reaction catalyzed with Eversa Transform. This model included the bimolecular transesterification reaction of Gly and EC catalyzed by the lipase and a reversible ring-opening polymerization of EC. Full article