Lipase Solution Research Articles

3D-printed porous titanium rods equipped with vancomycin-loaded hydrogels and polycaprolactone membranes for intelligent antibacterial drug release

Implant-related infections pose significant challenges to orthopedic surgeries due to the high risk of severe complications. The widespread use of bioactive prostheses in joint replacements, featuring roughened surfaces and tight integration with the bone marrow cavity, has facilitated bacterial proliferation and complicated treatment. Developing antibacterial coatings for orthopedic implants has been a key research focus in recent years to address this critical issue. Researchers have designed coatings using various materials and antibacterial strategies. In this study, we fabricated 3D-printed porous titanium rods, incorporated vancomycin-loaded mPEG750-b-PCL2500 gel, and coated them with a PCL layer. We then evaluated the antibacterial efficacy through both in vitro and in vivo experiments. Our coating passively inhibits bacterial biofilm formation and actively controls antibiotic release in response to bacterial growth, providing a practical solution for proactive and sustained infection control. This study utilized 3D printing technology to produce porous titanium rod implants simulating bioactive joint prostheses. The porous structure of the titanium rods was used to load a thermoresponsive gel, mPEG750-b-PCL2500 (PEG: polyethylene glycol; PCL: polycaprolactone), serving as a novel drug delivery system carrying vancomycin for controlled antibiotic release. The assembly was then covered with a PCL membrane that inhibits bacterial biofilm formation early in infection and degrades when exposed to lipase solutions, mimicking enzymatic activity during bacterial infections. This setup provides infection-responsive protection and promotes drug release. We investigated the coating’s controlled release, antibacterial capability, and biocompatibility through in vitro experiments. We established a Staphylococcus aureus infection model in rabbits, implanting titanium rods in the femoral medullary cavity. We evaluated the efficacy and safety of the composite coating in preventing implant-related infections using imaging, hematology, and pathology. In vitro experiments demonstrated that the PCL membrane stably protects encapsulated vancomycin during PBS immersion. The PCL membrane rapidly degraded at a lipase concentration of 0.2 mg/mL. The mPEG750-b-PCL2500 gel ensured stable and sustained vancomycin release, inhibiting bacterial growth. We investigated the antibacterial effect of the 3D-printed titanium material, coated with PCL and loaded with mPEG750-b-PCL2500 hydrogel, using a rabbit Staphylococcus aureus infection model. Imaging, hematology, and histopathology confirmed that our composite antibacterial coating exhibited excellent antibacterial effects and infection prevention, with good safety in trials. Our results indicate that the composite antibacterial coating effectively protects vancomycin in the hydrogel from premature release in the absence of bacterial infection. The outer PCL membrane inhibits bacterial growth and prevents biofilm formation. Upon contact with bacterial lipase, the PCL membrane rapidly degrades, releasing vancomycin for antibacterial action. The mPEG750-b-PCL2500 gel provides stable and sustained vancomycin release, prolonging its antibacterial effects. Our composite antibacterial coating demonstrates promising potential for clinical application.

Magnetic polydopamine nanoparticles as stabilisers for enzyme-Pickering emulsions: Application in the interfacial catalytic reaction of olive oil

Solid particles are essential for stabilising Pickering emulsions and improving interfacial catalytic reactions. We constructed magnetic polydopamine nanoparticles to stabilise lipase-Pickering emulsions for olive oil deacidification. The results showed that the nanoparticles had a core-shell structure with an average particle size of 605.8 nm, a zeta potential of −39.3 mV and a contact angle of 55.9°, which effectively stabilised the emulsion. The particles were added to the lipase solution and sonicated to construct the emulsion system. The emulsion droplets were the smallest and most uniformly distributed under 400 W ultrasonic irradiation for 10 min. The lipase adsorbed on the oil-water interface and promoted the hydrolysis of olive oil. The released fatty acid content increased 1.7-fold compared with the non-emulsion. This study not only provides a new immobilisation method for the interfacial catalysis of lipase but also provides ideas for the high-value utilisation of high acid-value oil resources.

Development of a fast and low-cost aqueous based-extraction protocol for the simultaneous extraction and characterization of SiO2 and TiO2 (nano)particles in confectionary products

BackgroundThe determination of (nano)particulate content from food additives has been a long-standing concern for authorities since it is of vital importance for ensuring food safety, regulatory adherence, and transparent consumer information. Nonetheless, a critical step in these determinations is the refinement of a careful and quantitative extraction process for particles that may be found within complex matrices such as confectionery products. The development of new technologies and analysis methods for nanoparticles is ongoing. Whereas new technologies and analysis methods for nanoparticles are being developed, the extraction of (nano)particles of different nature has not been adequately addressed in the literature. ResultsA simple aqueous extraction procedure was found to be suitable for the simultaneous extraction of TiO2 and SiO2 (nano)particles from five confectionery products. Neither the extraction agents (water, lipase, pancreatin and Tris-HCl solutions) nor the methods (manual shaking, ultrasonic bath, ultrasonic probe and ultrafiltration) altered the size, morphology, or aggregation state of either type of particle, as revealed by the micrographs obtained by Transmission Electron Microscopy (TEM). Single-particle ICP-MS (spICP-MS) determined that the optimal conditions for extracting both types of particles involve manual shaking using water as the solvent. Furthermore, the use of enzymes seemed to hinder the determination of both types of particles by spICP-MS. (Nano)particles of TiO2 and SiO2 were detected in all the confectionaries, even though the E171 additive was only labeled in one of them. The average percentage of nanoparticulate TiO2 material in the evaluated products was 30 %, while no nanometer-sized particles of SiO2 were detected. SignificanceEnsuring food safety, regulatory compliance and transparent consumer information relies on getting reliable results that connect with the application of sample treatment procedures for detecting unaltered nanoparticles in food products. The presented research introduces an economical, swift, user-friendly, environmentally responsible, and harmonious extraction method for the concurrent analysis of TiO2 and SiO2 particles in confectionery samples. Furthermore, particles from additives not included in the labeling have been detected, characterized, and quantified in the confectionary products.

Implantable Zinc Ion Battery and Osteogenesis-Immunoregulation Bifunction of Its Catabolite.

Biocompatible batteries can power implantable electronic devices and have broad applications in medicine. However, the controlled degradation of implantable batteries, the impact of battery catabolites on surrounding tissues, and wireless charging designs are often overlooked. Here, we designed an implantable zinc ion battery (ZIB) using a gelatin/polycaprolactone-based composite gel electrolyte. The prepared ZIBs deliver a high specific capacity of 244.0 mA h g-1 (0.5C) and long cycling stability of 300 cycles (4C). ZIBs were completely degraded within 8 weeks in rats and 30 days in a phosphate-buffered saline lipase solution, demonstrating good biocompatibility and degradability. ZIBs catabolites induced macrophage M2 polarization and exhibited anti-inflammatory properties, with mRNA levels of the M2 markers Arg-1 and CD206 up-regulated 15.8-fold and 13.4-fold, respectively, compared to the blank control group. Meanwhile, the expressions of two typical osteogenic markers, osteopontin and osteocalcin, were up-regulated by 3.6-fold and 5.6-fold, respectively, demonstrating that designed ZIBs promoted osteogenic differentiation of bone marrow mesenchymal stem cells. Additionally, a wireless energy transmission module was designed using 3D printing technology to realize real-time charging of the ZIB in rats. The designed ZIB is a promising power source for implantable medical electronic devices and also serves as a functional material to accelerate bone repair.

In vitro enzymatic degradation of the PTMC/cross-linked PEGDA blends.

Introduction: Poly(1,3-trimethylene carbonate) (PTMC) is a flexible amorphous polymer with good degradability and biocompatibility. The degradation of PTMC is critical for its application as a degradable polymer, more convenient and easy-to-control cross-linking strategies for preparing PTMC are required. Methods: The blends of poly(trimethylene carbonate) (PTMC) and cross-linked poly(ethylene glycol) diacrylate (PEGDA) were prepared by mixing photoactive PEGDA and PTMC and subsequently photopolymerizing the mixture with uv light. The physical properties and in vitro enzymatic degradation of the resultant PTMC/cross-linked PEGDA blends were investigated. Results: The results showed that the gel fraction of PTMC/cross-linked PEGDA blends increased while the swelling degree decreased with the content of PEGDA dosage. The results of in vitro enzymatic degradation confirmed that the degradation of PTMC/cross-linked PEGDA blends in the lipase solution occurred under the surface erosion mechanism, and the introduction of the uv cross-linked PEGDA significantly improved the resistance to lipase erosion of PTMC; the higher the cross-linking degree, the lower the mass loss. Discussion: The results indicated that the blends/cross-linking via PEGDA is a simple and effective strategy to tailor the degradation rate of PTMC.

Lipase adsorption during premix-membrane emulsification affects membrane surface properties and structural conformation of lipase

Fouling during membrane emulsification due to biomolecule adsorption is still a drawback for broader applicability and a better holistic understanding is needed. This study aimed to investigate the fouling effect on the membrane and the enzyme being modified due to adsorption. Therefore, a lipase solution with varying concentrations and pH was filtered through a silica-based membrane. The degree of adsorption, membrane properties (microstructure and phase wetting), and enzymatic characteristics (conformation and activity) were evaluated. For insights on the molecular level, molecular dynamic simulations of the conformational changes of lipase caused by adsorption were performed. Regarding the membrane, an increase in lipase concentration increased the adsorption leading to higher fouling and decreased wetting implying a higher hydrophobicity of the membrane. Additionally, SEM showed that the pH of the lipase solution modified the microstructure of the foulant layer. Regarding the impact on the lipase, molecular dynamic simulations revealed an increase in the hydrophobic surface area, a rearrangement of the C-alpha atoms of the protein backbone, and an increase in the radius of gyration. Despite leading to enzyme mass loss, both the secondary structure and the activity showed no significant differences after processing, which might be due to the reversible adsorption.

Investigation of nutritional profile, protein solubility and in vitro digestibility of various algae species as an alternative protein source for poultry feed

Alternative protein sources, particularly seaweed and microalgae, have long been considered a potential source of protein for poultry feed. Currently, several species of algae are a special focus of animal nutrition in order to replace soybean meal (SBM) due to its high protein content and abundance of vitamins, minerals and pigments. Determining nutrient and digestibility of a new ingredient is the first step in evaluating its suitability for use in poultry feeds. This study aimed to evaluate nutritional composition and digestibility of five algae including Caulerpa lentillifera J. Agardh, Ulva rigida C. Agardh, Spirulina sp., Coelastrella sp. (KKUP1) and Scenedesmus sp. (KKUP2). We evaluated nutritive value, amino acid profiles and physical characteristics microscopically. Protein solubility and in vitro digestibility, i.e., dilute pepsin digestibility (DPD) and two-phase gastric pancreatic digestibility (GPD), were performed by incubating algae samples in porcine pepsin and porcine pancreatin with a protease, lipase and amylase enzyme solution to determine suitability of algae as a protein ingredient in poultry feed. Results showed that Spirulina sp. had the highest protein content (44.44 % of dry matter basis; P < 0.0001) and was rich in amino acids (Lys, Thr and Trp). Moreover, protein solubility, digestibility (DPD and GPDProtein) and digestible protein of Spirulina sp. were significantly higher than those of other species (52.35 %, 49–67 % and 20.70 %, respectively). On the other hand, energy digestibility (GPDEnergy) and digestible energy were highest in Ulva rigida (99.40 % and 15.29 MJ kg−1, respectively; P < 0.0001). These results imply that Spirulina sp. was more suitable for utilization as an alternative protein source for SBM substitution in poultry feed formulation. This characterization of biochemical composition and in vitro digestibility of algae represents the preliminary methodology used to initially select algae for use as a protein source in animal feed and additional in vivo tests are warranted.

Aspergillus oryzae lipase-mediated in vitro enzymatic degradation of poly (2,2′-dimethyltrimethylene carbonate-co-ε-caprolactone)

The amino acid sequence and spatial structure of lipases from different sources often result in significant differences in the active sites, which exhibit differential activity when interacting with a particular polymer, as reflected in the rate of degradation of the polymer. The research of the degradation properties of enzymes for specific polymers can therefore be a helpful guide in production. In this study, a series of copolymer poly(2,2′-dimethyltrimethylene carbonate-co-ε-caprolactone) P(DTC-co-CL) was prepared and the in vitro enzymatic degradation behavior of the resultant copolymers was performed in the lipase solutions (from Aspergillus oryzae, ≥100,000 U/g), and the effect of the CL content in composition on the degradation behavior of P(DTC-co-CL) was investigated. The results showed that lipase significantly can accelerate the degradation rate of P(DTC-co-CL), and the mass loss of P(DTC-co-CL) strongly depended on the CL content due to the prior cleavage of ester bonds under the catalysis activity of lipase enzymes. For the copolymers containing 85 mol% CL, 37.9% of mass loss and 75.2% remaining CL content were observed after degradation of 15 days. Samples with 75 mol% DTC content can maintain good dimensional stability after the degradation, indicating that the introduction of DTC was beneficial to maintain the morphology. The results showed that P(DTC-co-CL) had adjustable degradation properties and well form-stability, which was a promising candidate for biomedical applications.

Bio-Based Materials versus Synthetic Polymers as a Support in Lipase Immobilization: Impact on Versatile Enzyme Activity

To improve enzyme stability, the immobilization process is often applied. The choice of a support on which the enzymes are adsorbed plays a major role in enhancing biocatalysts’ properties. In this study, bio-based (i.e., chitosan, coffee grounds) and synthetic (i.e., Lewatit VP OC 1600) supports were used in the immobilization of lipases of various microbial origins (yeast (Yarrowia lipolytica) and mold (Aspergillus oryzae)). The results confirmed that the enzyme proteins had been adsorbed on the surface of the selected carriers, but not all of them revealed comparably high catalytic activity. Immobilized CALB (Novozym 435) was used as a commercial reference biocatalyst. The best hydrolytic activity (higher than that of CALB) was observed for Novozym 51032 (lipase solution of A. oryzae) immobilized on Lewatit VP OC 1600. In terms of synthetic activity, there were only slight differences between the applied carriers for A. oryzae lipase, and the highest measures were obtained for coffee grounds. All of the biocatalysts had significantly lower activity in the synthesis reactions than the reference catalyst.

Electrospun Magnetic Composite Poly-3-hydroxybutyrate/Magnetite Scaffolds for Biomedical Applications: Composition, Structure, Magnetic Properties, and Biological Performance.

Magnetically responsive composite polymer scaffolds have good potential for a variety of biomedical applications. In this work, electrospun composite scaffolds made of polyhydroxybutyrate (PHB) and magnetite (Fe3O4) particles (MPs) were studied before and after degradation in either PBS or a lipase solution. MPs of different sizes with high saturation magnetization were synthesized by the coprecipitation method followed by coating with citric acid (CA). Nanosized MPs were prone to magnetite-maghemite phase transformation during scaffold fabrication, as revealed by Raman spectroscopy; however, for CA-functionalized nanoparticles, the main phase was found to be magnetite, with some traces of maghemite. Submicron MPs were resistant to the magnetite-maghemite phase transformation. MPs did not significantly affect the morphology and diameter of PHB fibers. The scaffolds containing CA-coated MPs lost 0.3 or 0.2% of mass in the lipase solution and PBS, respectively, whereas scaffolds doped with unmodified MPs showed no mass changes after 1 month of incubation in either medium. In all electrospun scaffolds, no alterations of the fiber morphology were observed. Possible mechanisms of the crystalline-lamellar-structure changes in hybrid PHB/Fe3O4 scaffolds during hydrolytic and enzymatic degradation are proposed. It was revealed that particle size and particle surface functionalization affect the mechanical properties of the hybrid scaffolds. The addition of unmodified MPs increased scaffolds' ultimate strength but reduced elongation at break after the biodegradation, whereas simultaneous increases in both parameters were observed for composite scaffolds doped with CA-coated MPs. The highest saturation magnetization─higher than that published in the literature─was registered for composite PHB scaffolds doped with submicron MPs. All PHB scaffolds proved to be biocompatible, and the ones doped with nanosized MPs yielded faster proliferation of rat mesenchymal stem cells. In addition, all electrospun scaffolds were able to support angiogenesis in vivo at 30 days after implantation in Wistar rats.

Screening for pancreatic lipase inhibitors: evaluating assay conditions using p-nitrophenyl palmitate as substrate

Current in vitro pancreatic lipase inhibitor screenings are based on previous spectrophotometric lipase assays. Nevertheless, they are with little evaluation of assay conditions. This study focuses on the impacts of experimental factors on enzyme activity in the assay with p-nitrophenyl palmitate as substrate by monitoring their effects on the hydrolysis rates. On the results, experimental conditions for lipase inhibitory assay were proposed. Notably, 5 mM sodium deoxycholate as emulsifier not only maintains the assay homogeneity but also enhances lipase activity. Organic co-solvents to dissolve organic inhibitors including DMSO, EtOH, MeOH, IPA, AcCN [0–30% (v/v)] was found well tolerated by the enzyme. With 10% (v/v) glycerol, lipase solutions can be stored at –20°C for up to one month without significant loss of activity. The results reported here provide researchers the assay condition sets in which most inhibitors can be dissolved, and lipase activity is not severely affected. This could accelerate the rational development of novel lipase inhibitors.

Tough and Degradable Self-Healing Elastomer from Synergistic Soft-Hard Segments Design for Biomechano-Robust Artificial Skin.

Increasing biomechanical applications of skin-inspired devices raise higher requirements for the skin-bionic robustness and environmental compatibility of elastomers. Here, a tough and degradable self-healing elastomer (TDSE) is developed by a synergistic soft-hard segments design. The polyester/polyether copolymer is introduced in soft segments to endow TDSE with flexibility and degradability. The two isomeric diamines are regulated in hard segments for elevating the toughness and fracture energy to 82.38 MJ/m3 and 43299 J/m2 and autonomous self-healing ability with 93% efficiency in 7 h for the TDSE. Employing TDSE and ionic liquid, a biomechano-robust artificial skin (BA-skin) is constructed with a stretch-insensitive mechanosensation capability during 50% cyclic stretching. The BA-skin has high biomechano-robustness to bear tear damage and good environmental compatibility with total decomposability in a lipase solution. This work provides a molecular design guideline for high-performance skin-bionic elastomers for applications in skin-inspired devices.

More Precise Control of the In Vitro Enzymatic Degradation via Ternary Self-Blending of High/Medium/Low Molecular Weight Poly(trimethylene carbonate)

To more precisely control the degradation rate of poly(trimethylene carbonate) (PTMC), self-blending films were prepared via the ternary self-blending of pure PTMC with a molecular weight of 334, 152, and 57 kg/mol. The in vitro enzymolysis degradation of the ternary self-blending films was performed in lipase solutions. The results showed that ternary self-blending could control the degradation of PTMC by adjusting the mass ratio of high/medium/low molecular weight PTMC in the composition, and the PTMC334/PTMC152/PTMC57 films with a mass ratio of 1/4/16 showed mass loss of 85.96% after seven weeks of degradation, while that of PTMC334/PTMC152/PTMC57 films with a mass ratio of 1/1/1 was 96.39%. The former and latter’s degradation rate constant was 13.263 and 23.981%/w, respectively, and the former presented better morphology stability than the latter. The strategy of ternary self-blending could simultaneously bestow PTMC with a lower degradation rate and good morphology stability, indicating that ternary self-blending is an efficient way to control the degradation performance of PTMC more precisely.

Controllable Degradation of Poly (trimethylene carbonate) via Self-blending with Different Molecular Weights

Blend films of Poly (trimethylene carbonate) (PTMC) homopolymers with different molecular weights were prepared. The in vitro enzymatic degradation tests were carried out in lipase solutions to investigate the effect of self-blending on the degradation performance of PTMC. It was observed that the mass loss decreased as the proportion of low molecular weight PTMC in the blend film increased. And the sample's mass loss with the mass ratio of PTMC334/PTMC57=1/16 reached almost 30% after seven weeks, which corresponded to the minimum degradation rate constant k value of 5.219. It is also indicated by the changes in weight as well as the macroscopic and microscopic morphology. Furthermore, during the degradation cycle, the thickness of the film also became thinner with the mass loss, confirming the surface erosion degradation mechanism of the PTMC blend films. The conclusion that PTMC does not produce acidic degradation products has also been confirmed. Finally, decreases in glass transition temperature (Tg) and thermal stability were found along with the film degraded, attributing to the accumulation of low molecular weight degradation products on the surface. In brief, the long-acting application of PTMC in biomedical fields could be satisfied by precisely tailoring the degradation properties via its self-blending with different molecular weights.

Effect of Additional Amino Group to Improve the Performance of Immobilized Lipase From Aspergillus niger by Adsorption-Crosslinking Method

Adsorption-crosslinking is one of the immobilization methods to improve the reusability of lipase. It requires amino groups to reduce cross-link immobilization risk so that lipase–support interaction increases and the immobilization is attainable. Also, the amino group on the support is expected to increase lipase performance. This study aimed to analyze the effect of amino group addition on immobilized Aspergillus niger lipase by the adsorption-crosslinking using MP-64 macroporous anion resin and XAD-7HP macroporous nonionic resin that has been treated with chitosan. The chitosan-coated resin was characterized by Fourier transform infrared spectrometry (FTIR) and scanning electron microscope (SEM). Lipase immobilization was carried out by adding 10 ml lipase solution containing 0.75 g resins and shaken at 25°C for 150 rpm. Adsorption was achieved for 4 h, followed by cross-linking separately (adding 0.5% (v/v) glutaraldehyde and re-reacting for 20 min). Lipase activity was measured with the titrimetric of olive oil emulsion; mixed with Aspergillus niger lipase, emulsion, and a buffer solution (pH 6.5, ionic strength of 0.7); and incubated for 30 min at 37°C. The effect of amino-functional groups was investigated based on lipase loading and lipase activity. The best lipase loading and lipase activity of 83.79% and 29.41 U/g support were achieved in the adsorption-crosslinking using MP-64 resin coated with chitosan. After four cycles, biodiesel synthesis was maintained at 70.61% of the initial yield. These results indicated that chitosan as an affordable and readily available source of amino groups could be used to modify support for Aspergillus niger lipase immobilization.

Ability of Ectoine to Stabilize Lipase against Elevated Temperatures and Methanol Concentrations

Ectoine is one of the compatible organic molecules that can protect the protein from heating, freezing, and chemicals contact. This study aims to investigate the ability of ectoine to stabilize lipase on heating and in methanol treatments as an effort to provide a stable biocatalyst for the production of biodiesel. Various ectoine concentrations were added to lipase solutions, then the mixture was heated, and the residual activity of the lipase was determined. Similar steps were also conducted for methanol treatment. The results showed that ectoine maintained and even improved the catalytic activity of lipase after treatment with either heat or methanol. The addition of ectoine to a final concentration of 110 to 150 mM could maintain lipase activity up to 80% when heating to approximately 95 °C. Additionally, more than 20% of lipase activity increased on heating to temperatures below 75 °C in the presence of ectoine at a final concentration of 25 to 120 mM. Meanwhile, after incubation in methanol at a level of around 84% (v/v), the activity of lipase containing 40–90 mM ectoine was maintained. These results demonstrated that ectoine was highly effective in protecting lipase from heat and methanol.

Degradation of Staphylococcus aureus Biofilm Using Hydrolytic Enzymes Produced by Amazonian Endophytic Fungi.

Microbial biofilms can cause serious health problems, since, due to their persistent character, they often function as spreaders of contaminants. Hydrolytic enzymes have a number of industrial applications and have been indicated as an alternative to the traditional chemical methods that are used to eradicate microbial biofilms. In this study, we evaluated the ability of enzymatic extracts produced by endophytic fungi isolated from the Amazonian species Myrcia guianensis to remove Staphylococcus aureus biofilms. After culture in liquid medium, the fungal hydrolytic extracts showed amylase (3.77 U/mL), lipase (3.84 U/mL), protease (3.63 U/mL), and xylanase (2.91 U/mL) activity. A 24 h mature S. aureus ATCC6538 biofilm was exposed to each enzyme extract with standardized enzyme activities for 10, 30, and 60 min. The optical density at 630 nm was used to calculate the growth rate (GR%) and the residual biofilm rate (RBR%). The most promising solutions were used in combination, based on a 24 factorial design for 0, 10, 20, and 30 min of exposure. Lipase and protease solutions, when applied separately, were the most effective, and promoted the complete removal of S. aureus biofilms in t10 (lipase) and t30 and t60 (lipase and protease). Of the combined treatments using 1.0 U/mL protease and 0.4 U/mL lipase, total biofilm degradation was observed for all exposure times. Thus, the hydrolases produced by the Amazonian endophytic fungi evaluated here are highlighted as an interesting tool in the fight against microbial biofilms.

Periodic UV-C Light Treatment for Reducing the Formation of Free Fatty Acids in Crude Palm Oil During Storage

The formation of free fatty acids (FFA) during long term storage of crude palm oil (CPO) is inevitable, and it can reduce the quality and losing the CPO. Therefore, this study aims to evaluate the effect of UV-C light on lipase enzyme deactivation and the effect of periodic UV-C light treatment to reduce the FFA formation in the CPO during storage. The lipase deactivation was evaluated by exposing UV-C light to the lipase solution in the range of 2 to 8 hours at various dose rates of 0.8528, 1.2318 and 1.7238 (mW/cm2) and various periodic exposure times (2. 4 and 6 hours/day) for 7 to 28 storage days. The FFA level was analyzed using the NaOH titration method. The deactivation kinetics followed first-order model with deactivation rate constant in the range of 3.4 10-3 -5.8 10-3 min-1. The half-life was 204.168, 150.586 and 120.024 (min) respectively. The highest value of FFA formation reduction is 85.6% at a dose rate of 1.7238 mW/cm2 and a periodic exposure time of 6 h/day for 28 days storage. Overall, the experimental results show that UV-C treatments were able to deactivate lipase enzymes and reduce the rate of FFA formation in CPO during storage.

Study on the degradation of biodegradable poly (glycerol maleate) (PGM) microbeads

Plastics contributed from personal care products and plastic fragments are considered as one of the most common pollutants in the ocean since 1970s. In this study, poly (glycerol maleate) (PGM) is applied as the alternative of microbeads due to its high degradability in the water and the relatively low cost compared to other biodegradable polymers. The proposed PGM microbeads are fabricated via solvent evaporation methods with average diameter around 30 ± 13 μm and polydispersity index around 0.2 to 0.3. To identify the degradability of PGM microbeads in different water solutions, samples were examined in buffer solution with different pH values, DI water, sea water and enzyme solution through total organic carbon (TOC) analyzer/UV–Vis spectrometry, microscopy, and SEM. These microbeads were completely degraded in 45 min in alkaline solution (pH 10). In contrast, 60% of PGM microbeads were degraded in 30 days in the acidic solution (pH 4). It revealed that the base catalysis of hydrolysis was quicker than acid-catalysis. 50% more of PGM microbeads were degraded in the refreshed DI water in a month. However, only 36% of microbeads were degraded in synthetic sea water. The high salinity was suspected to obstruct the hydrolysis of PGM microbeads and slow down the degradation rate. Lipase solution is conducted to examine the possibility of bio-accumulation once PGM microbeads ingested inside the living organism, and the result shows that PGM microbeads degrade mostly in seven days. It is worthy to note that PLA microbeads only degrade at pH 10 in this study. With the comparison between PGM and PLA microbeads, PGM is more easily degraded and affordable, and it is thought to have great potential for being the alternative to plastic microbeads.

Comparative Structure-Property Characterization of Poly(3-Hydroxybutyrate-Co-3-Hydroxyvalerate)s Films under Hydrolytic and Enzymatic Degradation: Finding a Transition Point in 3-Hydroxyvalerate Content.

The hydrolytic and enzymatic degradation of polymer films of poly(3-hydroxybutyrate) (PHB) of different molecular mass and its copolymers with 3-hydroxyvalerate (PHBV) of different 3-hydroxyvalerate (3-HV) content and molecular mass, 3-hydroxy-4-methylvalerate (PHB4MV), and polyethylene glycol (PHBV-PEG) produced by the Azotobacter chroococcum 7B by controlled biosynthesis technique were studied under in vitro model conditions. The changes in the physicochemical properties of the polymers during their in vitro degradation in the pancreatic lipase solution and in phosphate-buffered saline for a long time (183 days) were investigated using different analytical techniques. A mathematical model was used to analyze the kinetics of hydrolytic degradation of poly(3-hydroxyaklannoate)s by not autocatalytic and autocatalytic hydrolysis mechanisms. It was also shown that the degree of crystallinity of some polymers changes differently during degradation in vitro. The total mass of the films decreased slightly up to 8–9% (for the high-molecular weight PHBV with the 3-HV content 17.6% and 9%), in contrast to the copolymer molecular mass, the decrease of which reached 80%. The contact angle for all copolymers after the enzymatic degradation decreased by an average value of 23% compared to 17% after the hydrolytic degradation. Young’s modulus increased up to 2-fold. It was shown that the effect of autocatalysis was observed during enzymatic degradation, while autocatalysis was not available during hydrolytic degradation. During hydrolytic and enzymatic degradation in vitro, it was found that PHBV, containing 5.7–5.9 mol.% 3-HV and having about 50% crystallinity degree, presents critical content, beyond which the structural and mechanical properties of the copolymer have essentially changed. The obtained results could be applicable to biomedical polymer systems and food packaging materials.