Rice husk is an underexploited, low density and highly robust composite material, massively avail... more Rice husk is an underexploited, low density and highly robust composite material, massively available from rice processing. Here we report two new procedures for the formulation of immobilized lipases applicable in fats and oils transformations. The enzymes were covalently anchored on aldehyde groups introduced on rice husk by laccase-catalysed oxidation of the cellulose component. The method avoids the use of toxic glutaraldehyde while allows for the application and recycling of the biocatalysts in aqueous media. The second method used a fluidized bed granulator for the coating of the particles of rice husk (200-400 m) in the presence of water-soluble binders. The formulations are mechanically stable and suitable for applications in different hydrophobic media. Both methods allow for the recovery and reuse of the rice husk at the end of the life cycle of the biocatalysts.
In relation to the development of environmentally-friendly processing technologies for the contin... more In relation to the development of environmentally-friendly processing technologies for the continuously growing market of plastics, enzymes play an important role as green and sustainable biocatalysts. The present study reports the use of heterogeneous immobilized biocatalysts in solvent-free systems for the synthesis of aliphatic oligoesters with Mws and monomer conversions up to 1500 Da and 74%, respectively. To improve the accessibility of hydrophilic and hydrophobic substrates to the surface of the biocatalyst and improve the reaction kinetic and the chain elongation, two different binding modules were fused on the surface of cutinase 1 from Thermobifida cellulosilytica. The fusion enzymes were successfully immobilized (>99% of bound protein) via covalent bonding onto epoxy-activated beads. To the best of our knowledge, this is the first example where fused enzymes are used to catalyze transesterification reactions for polymer synthesis purposes.
The lipase catalyzed polycondensation of azelaic acid and glycerol was investigated according to ... more The lipase catalyzed polycondensation of azelaic acid and glycerol was investigated according to a Design of Experiment approach that allowed to understand the effect of the experimental variables on monomer conversion, M n and regioselectivity of acylation of glycerol. The chemometric analysis showed that after 24h the reaction proceeds regardless of the presence of the enzyme. Accordingly, the biocatalyst was removed after a first step of synthesis and the chain elongation continued at 80°C. That allowed the removal of the biocatalyst and the preservation of its activity: pre-requites for efficient applicability at industrial scale. The experimental study, combined with docking based computational analysis, provided rational guidelines for the optimization of the regioselective acylation of glycerol. Overall, the process was scaled up to 73.5 g of monomer. The novelty of the present study stays in the rigorous control of the reaction conditions and of the integrity of the immobilized biocatalyst, thus avoiding any interference of free enzyme or fines released in the reaction mixture. The quantitative analysis of the effect of the experimental conditions and the overcoming of the major technical bottlenecks for the scalability of enzymatic polycondensation opens new scenarios for its industrial exploitation.
The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a... more The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a valuable raw material, particularly for controlled drug delivery and tis-sue engineering applications. However, the usefulness of such materials is limited by their low hydrophilicity and slow biodegradation rate. In order to improve polycapro-lactone properties and functionalities, copolymerization of ε-caprolactone with δ-gluconolactone was investigat-ed. Since enzymatic reactions involving sugars are usu-ally hindered by the low solubility of these compounds in common organic solvents, finding the best reaction medium was a major objective of this research. The op-timal copolymerization conditions were set up by using different organic media (solvent and solvents mixtures), as well as solvent free systems that are able to dissolve (completely or partially) sugars, and are nontoxic for en-zymes. Native and immobilized lipases by different im-mobilization techniques from Candida antarc...
Biocatalysis has developed in the last decades as a major tool for green polymer synthesis. The p... more 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 ...
The drug-loaded nanocarriers have overcome various challenges compared with the pure chemotherape... more The drug-loaded nanocarriers have overcome various challenges compared with the pure chemotherapeutic drug, such as limited bioavailability, multiple drug resistance, poor patient compliance, and adverse drug reactions, offering advantages such as protection from degradation in the blood stream, better drug solubility, and improved drug stability. One promising group of controlled and targeted drug delivery systems is polymer-based nanoparticles that can sustain the release of the active agent by diffusion and their degradation. Sorafenib is the only drug that can prolong the life of patients suffering from hepatocellular carcinoma. Cisplatin remains one of the most widely used broad-spectrum anticancer drugs for the treatment of a variety of solid tumours. Nanoformulations can exert a synergistic effect by entrapping two drugs with different modes of action, such as sorafenib and cisplatin. In our study, polymeric nanoparticles were prepared with a good production yield by an impro...
Cutinases are bacterial and fungal enzymes that catalyze the hydrolysis of natural cutin, a three... more Cutinases are bacterial and fungal enzymes that catalyze the hydrolysis of natural cutin, a three-dimensional inter-esterified polyester with epoxy-hydroxy fatty acids with chain lengths between 16 and 18 carbon atoms. Due to their ability to accept long chain substrates, cutinases are also effective in catalyzing in vitro both the degradation and synthesis of several synthetic polyesters and polyamides. Here, we present a bioinformatics study that intends to correlate the structural features of cutinases with their catalytic properties to provide rational basis for their effective exploitation, particularly in polymer synthesis and biodegradation. The bioinformatics study used the BioGPS method (Global Positioning System in Biological Space) that computed molecular descriptors based on Molecular Interaction Fields (MIFs) described in the GRID force field. The information was used to generate catalophores, spatial representations of the ability of each enzymatic active site to estab...
Biotechnological Progress and Beverage Consumption, 2020
Abstract As much as digesting of lactose emerged as an important health and nutritional problem a... more Abstract As much as digesting of lactose emerged as an important health and nutritional problem and the deficiency of this hydrolytic enzyme showed increasing tendency, the consumption of lactose-free beverages became a possible solution for people owing lactose intolerance. Therefore, β- d -galactosidase (β-GAL), the enzyme responsible for lactose hydrolysis to glucose and galactose, has achieved wide utilization in the food technology, mainly in the dairy industry. In the same time, β-GAL is able to catalyze the transgalactosylation reaction leading to galacto-oligosaccharides (GOS). GOS belong to the group of nondigestible prebiotics that beneficially affect the organisms by stimulating the growth and activity of useful bacteria in the colon, reducing the gastrointestinal discomfort. GOS fortified foods and beverages have an important and increasing market potential in all age groups, but particularly in infant population. The GOS market is already consolidated, but technological improvements are always needed. Immobilization of enzymes is a well-known method to improve the stability and confer reusability of the enzymes, particularly in large-scale applications. The utilization of immobilized β-GAL for lactose hydrolysis was subject of numerous studies, while GOS synthesis with the same biocatalyst involves specific requirements, particularly when continuous processes are targeted. This review presents the recent advancements in the topic of β-GAL immobilization by various methods and a comparative overview on the main approaches concerning the synthesis of short-chain GOS using the immobilized biocatalyst, with possible applications in the beverage industry.
New technologies for the conversion of biomass into high-value chemicals, including polymers and ... more New technologies for the conversion of biomass into high-value chemicals, including polymers and plastics, is a must and a challenge. The development of green processes in the last decade involved a continuous increase of the interest towards the synthesis of polymers using in vitro biocatalysis. Among the remarkable diversity of new bio-based polymeric products meeting the criteria of sustainability, biocompatibility, and eco-friendliness, a wide range of polyesters with shorter chain length were obtained and characterized, targeting biomedical and cosmetic applications. In this review, selected examples of such specialty polymers are presented, highlighting the recent developments concerning the use of lipases, mostly in immobilized form, for the green synthesis of ε-caprolactone co-polymers, polyesters with itaconate or furan units, estolides, and polyesteramides. The significant process parameters influencing the average molecular weights and other characteristics are discussed,...
An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- a... more An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- and oligosaccharide esters is described. Acetal derivatives of glucose, sucrose, lactose and inulin were obtained by chemical synthesis. The fully characterized pure sugar acetals were subjected to enzymatic esterification with 3-(4-hydroxyphenyl) propionic acid (HPPA) in the presence of Novozyme 435 lipase as a biocatalyst. The aromatic esters of alkyl glycosides and glucose acetal were obtained with good esterification yields, characterized by mass spectrometry (MALDI-TOF MS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR). The synthesis of aromatic esters of disaccharide acetals was successful only for the enzymatic esterification of sucrose acetal. The new chemoenzymatic route allowed the synthesis of novel aromatic esters of inulin as the inulin monoacetal monoester and diester and the inulin diacetal monoester with a polymerization degree ...
The thermal behavior of co-oligomers of ε-caprolactone (ECL) with gluconolactone, compared to the... more The thermal behavior of co-oligomers of ε-caprolactone (ECL) with gluconolactone, compared to the ε-caprolactone oligomer, has been assessed by thermogravimetric analysis, while differential scanning calorimetry was used to evaluate the melting comportment. As the insertion of more hydrophilic structural units can improve the properties and functionalities of the ECL oligoesters, the enzymatic in vitro oligomerization process was optimized by a 3-factorial/3-level experimental design, using the Box–Behnken method. The selected independent variables were the temperature, the enzyme amount, and the molar ratio of monomers, while the co-oligomerization degree and the mass average molecular mass (calculated from MALDI-TOF MS data) were the response variables. The results indicate that temperature has the most significant effect and is directly correlated with the formation of linear co-oligoesters. The overall effect of the other variables was also significant. The thermogravimetric analysis of the co-oligomer synthesized in the optimized conditions indicated a decrease of the thermal stability and compared to the ECL oligomer. Thermoanalytical techniques can consistently improve the utilization efficiency of polymer-based formulations in pharmaceutical and medical applications.
Abstract One-pot cascade reaction systems offer several process and technological benefits, compl... more Abstract One-pot cascade reaction systems offer several process and technological benefits, completed by the opportunity of the second enzyme to act on a convenient concentration of its substrate. Most of the reported cascade reactions involve immobilization of both biocatalysts on a single support, but in this case the catalytic performance of the whole system is affected if the activity of either enzyme drops. In this work, tailor-made immobilization of two β-galactosidases (from Kluyveromyces lactis and Aspergillus oryzae) and a glucose oxidase (from Aspergillus niger) was investigated, to subsequent utilization of the best performing immobilized biocatalyst of each type for the one-pot conversion of lactose to gluconic acid and galacto-oligosaccharides. The immobilization was performed by covalent binding onto amino-terminated Ni0.4Co0.2Zn0.4Fe2O4 and Ni0,5Zn0,5Fe2O4 magnetic particles and commercial amino- and epoxy-functionalized methacrylate supports. The highest activity for β-galactosidases was achieved on Ni0.5Zn0.5-Fe2O4 magnetic particles, meanwhile the glucose oxidase showed higher affinity for the supports with epoxy active groups. The immobilized biocatalysts have been characterized in detail, demonstrating enhanced storage, pH, and thermal stability as well as better operational stability compared to the soluble enzymes.
The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a... more The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a valuable raw material, particularly for controlled drug delivery and tissue engineering applications. However, the usefulness of such materials is limited by their low hydrophilicity and slow biodegradation rate. In order to improve polycaprolactone properties and functionalities, copolymerization of ε-caprolactone with δ-gluconolactone was investigated. Since enzymatic reactions involving sugars are usually hindered by the low solubility of these compounds in common organic solvents, finding the best reaction medium was a major objective of this research. The optimal copolymerization conditions were set up by using different organic media (solvent and solvents mixtures), as well as solvent free systems that are able to dissolve (completely or partially) sugars, and are nontoxic for enzymes. Native and immobilized lipases by different immobilization techniques from Candida antarctica B ...
This work develops a methodology for selective removal of industrial dyes from wastewaters using ... more This work develops a methodology for selective removal of industrial dyes from wastewaters using adsorption technology based on magnetic adsorbents. The magnetic nanoparticles embedded within a matrix of activated carbon were tested as adsorbents for removal of industrial dyes from aqueous solutions. The effects of four independent variables, solution pH, initial concentration of pollutant, adsorbent dose, contact time, and their interactions on the adsorption capacity of the nanocomposite were investigated in order to optimize the process. The removal efficiency of pollutants depends on solution pH and increases with increasing the carbon content, with initial concentration of the pollutants, the temperature, and the dose of magnetite/carbon nanocomposites. Pseudo-second-order kinetic model was fitted to the kinetic data, and adsorption isotherm analysis and thermodynamics were used to elucidate the adsorption mechanism. The maximum adsorption capacities were 223.82 mg g−1 for Nylo...
Developments of past years placed the bio-based polyesters as competitive substitutes for fossil-... more Developments of past years placed the bio-based polyesters as competitive substitutes for fossil-based polymers. Moreover, enzymatic polymerization using lipase catalysts has become an important green alternative to chemical polymerization for the synthesis of polyesters with biomedical applications, as several drawbacks related to the presence of traces of metal catalysts, toxicity and higher temperatures could be avoided. Copolymerization of ϵ-caprolactone (CL) with four hydroxy-fatty acids (HFA) from renewable sources, 10-hydroxystearic acid, 12-hydroxystearic acid, ricinoleic acid, and 16-hydroxyhexadecanoic acid, was carried out using commercially available immobilized lipases from Candida antarctica B, Thermomyces lanuginosus, and Pseudomonas stutzeri, as well as a native lipase. MALDI-TOF-MS and 2D-NMR analysis confirmed the formation of linear/branched and cyclic oligomers with average molecular weight around 1200 and polymerization degree up to 15. The appropriate selection...
Rice husk is an underexploited, low density and highly robust composite material, massively avail... more Rice husk is an underexploited, low density and highly robust composite material, massively available from rice processing. Here we report two new procedures for the formulation of immobilized lipases applicable in fats and oils transformations. The enzymes were covalently anchored on aldehyde groups introduced on rice husk by laccase-catalysed oxidation of the cellulose component. The method avoids the use of toxic glutaraldehyde while allows for the application and recycling of the biocatalysts in aqueous media. The second method used a fluidized bed granulator for the coating of the particles of rice husk (200-400 m) in the presence of water-soluble binders. The formulations are mechanically stable and suitable for applications in different hydrophobic media. Both methods allow for the recovery and reuse of the rice husk at the end of the life cycle of the biocatalysts.
In relation to the development of environmentally-friendly processing technologies for the contin... more In relation to the development of environmentally-friendly processing technologies for the continuously growing market of plastics, enzymes play an important role as green and sustainable biocatalysts. The present study reports the use of heterogeneous immobilized biocatalysts in solvent-free systems for the synthesis of aliphatic oligoesters with Mws and monomer conversions up to 1500 Da and 74%, respectively. To improve the accessibility of hydrophilic and hydrophobic substrates to the surface of the biocatalyst and improve the reaction kinetic and the chain elongation, two different binding modules were fused on the surface of cutinase 1 from Thermobifida cellulosilytica. The fusion enzymes were successfully immobilized (>99% of bound protein) via covalent bonding onto epoxy-activated beads. To the best of our knowledge, this is the first example where fused enzymes are used to catalyze transesterification reactions for polymer synthesis purposes.
The lipase catalyzed polycondensation of azelaic acid and glycerol was investigated according to ... more The lipase catalyzed polycondensation of azelaic acid and glycerol was investigated according to a Design of Experiment approach that allowed to understand the effect of the experimental variables on monomer conversion, M n and regioselectivity of acylation of glycerol. The chemometric analysis showed that after 24h the reaction proceeds regardless of the presence of the enzyme. Accordingly, the biocatalyst was removed after a first step of synthesis and the chain elongation continued at 80°C. That allowed the removal of the biocatalyst and the preservation of its activity: pre-requites for efficient applicability at industrial scale. The experimental study, combined with docking based computational analysis, provided rational guidelines for the optimization of the regioselective acylation of glycerol. Overall, the process was scaled up to 73.5 g of monomer. The novelty of the present study stays in the rigorous control of the reaction conditions and of the integrity of the immobilized biocatalyst, thus avoiding any interference of free enzyme or fines released in the reaction mixture. The quantitative analysis of the effect of the experimental conditions and the overcoming of the major technical bottlenecks for the scalability of enzymatic polycondensation opens new scenarios for its industrial exploitation.
The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a... more The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a valuable raw material, particularly for controlled drug delivery and tis-sue engineering applications. However, the usefulness of such materials is limited by their low hydrophilicity and slow biodegradation rate. In order to improve polycapro-lactone properties and functionalities, copolymerization of ε-caprolactone with δ-gluconolactone was investigat-ed. Since enzymatic reactions involving sugars are usu-ally hindered by the low solubility of these compounds in common organic solvents, finding the best reaction medium was a major objective of this research. The op-timal copolymerization conditions were set up by using different organic media (solvent and solvents mixtures), as well as solvent free systems that are able to dissolve (completely or partially) sugars, and are nontoxic for en-zymes. Native and immobilized lipases by different im-mobilization techniques from Candida antarc...
Biocatalysis has developed in the last decades as a major tool for green polymer synthesis. The p... more 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 ...
The drug-loaded nanocarriers have overcome various challenges compared with the pure chemotherape... more The drug-loaded nanocarriers have overcome various challenges compared with the pure chemotherapeutic drug, such as limited bioavailability, multiple drug resistance, poor patient compliance, and adverse drug reactions, offering advantages such as protection from degradation in the blood stream, better drug solubility, and improved drug stability. One promising group of controlled and targeted drug delivery systems is polymer-based nanoparticles that can sustain the release of the active agent by diffusion and their degradation. Sorafenib is the only drug that can prolong the life of patients suffering from hepatocellular carcinoma. Cisplatin remains one of the most widely used broad-spectrum anticancer drugs for the treatment of a variety of solid tumours. Nanoformulations can exert a synergistic effect by entrapping two drugs with different modes of action, such as sorafenib and cisplatin. In our study, polymeric nanoparticles were prepared with a good production yield by an impro...
Cutinases are bacterial and fungal enzymes that catalyze the hydrolysis of natural cutin, a three... more Cutinases are bacterial and fungal enzymes that catalyze the hydrolysis of natural cutin, a three-dimensional inter-esterified polyester with epoxy-hydroxy fatty acids with chain lengths between 16 and 18 carbon atoms. Due to their ability to accept long chain substrates, cutinases are also effective in catalyzing in vitro both the degradation and synthesis of several synthetic polyesters and polyamides. Here, we present a bioinformatics study that intends to correlate the structural features of cutinases with their catalytic properties to provide rational basis for their effective exploitation, particularly in polymer synthesis and biodegradation. The bioinformatics study used the BioGPS method (Global Positioning System in Biological Space) that computed molecular descriptors based on Molecular Interaction Fields (MIFs) described in the GRID force field. The information was used to generate catalophores, spatial representations of the ability of each enzymatic active site to estab...
Biotechnological Progress and Beverage Consumption, 2020
Abstract As much as digesting of lactose emerged as an important health and nutritional problem a... more Abstract As much as digesting of lactose emerged as an important health and nutritional problem and the deficiency of this hydrolytic enzyme showed increasing tendency, the consumption of lactose-free beverages became a possible solution for people owing lactose intolerance. Therefore, β- d -galactosidase (β-GAL), the enzyme responsible for lactose hydrolysis to glucose and galactose, has achieved wide utilization in the food technology, mainly in the dairy industry. In the same time, β-GAL is able to catalyze the transgalactosylation reaction leading to galacto-oligosaccharides (GOS). GOS belong to the group of nondigestible prebiotics that beneficially affect the organisms by stimulating the growth and activity of useful bacteria in the colon, reducing the gastrointestinal discomfort. GOS fortified foods and beverages have an important and increasing market potential in all age groups, but particularly in infant population. The GOS market is already consolidated, but technological improvements are always needed. Immobilization of enzymes is a well-known method to improve the stability and confer reusability of the enzymes, particularly in large-scale applications. The utilization of immobilized β-GAL for lactose hydrolysis was subject of numerous studies, while GOS synthesis with the same biocatalyst involves specific requirements, particularly when continuous processes are targeted. This review presents the recent advancements in the topic of β-GAL immobilization by various methods and a comparative overview on the main approaches concerning the synthesis of short-chain GOS using the immobilized biocatalyst, with possible applications in the beverage industry.
New technologies for the conversion of biomass into high-value chemicals, including polymers and ... more New technologies for the conversion of biomass into high-value chemicals, including polymers and plastics, is a must and a challenge. The development of green processes in the last decade involved a continuous increase of the interest towards the synthesis of polymers using in vitro biocatalysis. Among the remarkable diversity of new bio-based polymeric products meeting the criteria of sustainability, biocompatibility, and eco-friendliness, a wide range of polyesters with shorter chain length were obtained and characterized, targeting biomedical and cosmetic applications. In this review, selected examples of such specialty polymers are presented, highlighting the recent developments concerning the use of lipases, mostly in immobilized form, for the green synthesis of ε-caprolactone co-polymers, polyesters with itaconate or furan units, estolides, and polyesteramides. The significant process parameters influencing the average molecular weights and other characteristics are discussed,...
An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- a... more An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- and oligosaccharide esters is described. Acetal derivatives of glucose, sucrose, lactose and inulin were obtained by chemical synthesis. The fully characterized pure sugar acetals were subjected to enzymatic esterification with 3-(4-hydroxyphenyl) propionic acid (HPPA) in the presence of Novozyme 435 lipase as a biocatalyst. The aromatic esters of alkyl glycosides and glucose acetal were obtained with good esterification yields, characterized by mass spectrometry (MALDI-TOF MS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR). The synthesis of aromatic esters of disaccharide acetals was successful only for the enzymatic esterification of sucrose acetal. The new chemoenzymatic route allowed the synthesis of novel aromatic esters of inulin as the inulin monoacetal monoester and diester and the inulin diacetal monoester with a polymerization degree ...
The thermal behavior of co-oligomers of ε-caprolactone (ECL) with gluconolactone, compared to the... more The thermal behavior of co-oligomers of ε-caprolactone (ECL) with gluconolactone, compared to the ε-caprolactone oligomer, has been assessed by thermogravimetric analysis, while differential scanning calorimetry was used to evaluate the melting comportment. As the insertion of more hydrophilic structural units can improve the properties and functionalities of the ECL oligoesters, the enzymatic in vitro oligomerization process was optimized by a 3-factorial/3-level experimental design, using the Box–Behnken method. The selected independent variables were the temperature, the enzyme amount, and the molar ratio of monomers, while the co-oligomerization degree and the mass average molecular mass (calculated from MALDI-TOF MS data) were the response variables. The results indicate that temperature has the most significant effect and is directly correlated with the formation of linear co-oligoesters. The overall effect of the other variables was also significant. The thermogravimetric analysis of the co-oligomer synthesized in the optimized conditions indicated a decrease of the thermal stability and compared to the ECL oligomer. Thermoanalytical techniques can consistently improve the utilization efficiency of polymer-based formulations in pharmaceutical and medical applications.
Abstract One-pot cascade reaction systems offer several process and technological benefits, compl... more Abstract One-pot cascade reaction systems offer several process and technological benefits, completed by the opportunity of the second enzyme to act on a convenient concentration of its substrate. Most of the reported cascade reactions involve immobilization of both biocatalysts on a single support, but in this case the catalytic performance of the whole system is affected if the activity of either enzyme drops. In this work, tailor-made immobilization of two β-galactosidases (from Kluyveromyces lactis and Aspergillus oryzae) and a glucose oxidase (from Aspergillus niger) was investigated, to subsequent utilization of the best performing immobilized biocatalyst of each type for the one-pot conversion of lactose to gluconic acid and galacto-oligosaccharides. The immobilization was performed by covalent binding onto amino-terminated Ni0.4Co0.2Zn0.4Fe2O4 and Ni0,5Zn0,5Fe2O4 magnetic particles and commercial amino- and epoxy-functionalized methacrylate supports. The highest activity for β-galactosidases was achieved on Ni0.5Zn0.5-Fe2O4 magnetic particles, meanwhile the glucose oxidase showed higher affinity for the supports with epoxy active groups. The immobilized biocatalysts have been characterized in detail, demonstrating enhanced storage, pH, and thermal stability as well as better operational stability compared to the soluble enzymes.
The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a... more The biodegradability and biocompatibility properties of ε-caprolactone homopolymers place it as a valuable raw material, particularly for controlled drug delivery and tissue engineering applications. However, the usefulness of such materials is limited by their low hydrophilicity and slow biodegradation rate. In order to improve polycaprolactone properties and functionalities, copolymerization of ε-caprolactone with δ-gluconolactone was investigated. Since enzymatic reactions involving sugars are usually hindered by the low solubility of these compounds in common organic solvents, finding the best reaction medium was a major objective of this research. The optimal copolymerization conditions were set up by using different organic media (solvent and solvents mixtures), as well as solvent free systems that are able to dissolve (completely or partially) sugars, and are nontoxic for enzymes. Native and immobilized lipases by different immobilization techniques from Candida antarctica B ...
This work develops a methodology for selective removal of industrial dyes from wastewaters using ... more This work develops a methodology for selective removal of industrial dyes from wastewaters using adsorption technology based on magnetic adsorbents. The magnetic nanoparticles embedded within a matrix of activated carbon were tested as adsorbents for removal of industrial dyes from aqueous solutions. The effects of four independent variables, solution pH, initial concentration of pollutant, adsorbent dose, contact time, and their interactions on the adsorption capacity of the nanocomposite were investigated in order to optimize the process. The removal efficiency of pollutants depends on solution pH and increases with increasing the carbon content, with initial concentration of the pollutants, the temperature, and the dose of magnetite/carbon nanocomposites. Pseudo-second-order kinetic model was fitted to the kinetic data, and adsorption isotherm analysis and thermodynamics were used to elucidate the adsorption mechanism. The maximum adsorption capacities were 223.82 mg g−1 for Nylo...
Developments of past years placed the bio-based polyesters as competitive substitutes for fossil-... more Developments of past years placed the bio-based polyesters as competitive substitutes for fossil-based polymers. Moreover, enzymatic polymerization using lipase catalysts has become an important green alternative to chemical polymerization for the synthesis of polyesters with biomedical applications, as several drawbacks related to the presence of traces of metal catalysts, toxicity and higher temperatures could be avoided. Copolymerization of ϵ-caprolactone (CL) with four hydroxy-fatty acids (HFA) from renewable sources, 10-hydroxystearic acid, 12-hydroxystearic acid, ricinoleic acid, and 16-hydroxyhexadecanoic acid, was carried out using commercially available immobilized lipases from Candida antarctica B, Thermomyces lanuginosus, and Pseudomonas stutzeri, as well as a native lipase. MALDI-TOF-MS and 2D-NMR analysis confirmed the formation of linear/branched and cyclic oligomers with average molecular weight around 1200 and polymerization degree up to 15. The appropriate selection...
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