Glycol Modification Research Articles

Removal of various aqueous heavy metals by polyethylene glycol modified MgAl-LDH: Adsorption mechanisms and vital role of precipitation

The adsorption mechanisms of layered double hydroxides (LDHs) for aqueous heavy metals have been studied extensively, but few prior quantitative investigations of each mechanism were conducted. In this work, we prepared polyethylene glycol modified MgAl-LDH with molecular weight of 200 and 4000 (LDH-200 and LDH-4000) to investigate the adsorption mechanisms for Cu(II), Pb(II), and Cd(II) qualitatively and quantitatively. The interaction mechanisms were conducted by a number of characterization methods and quantitatively analyzed by a series of extraction procedures. The results indicated that the leading mechanisms of LDH-200 and LDH-4000 for Cu(II), Pb(II), and Cd(II) were precipitation with contributions of 44.20%-72.12%. The percentages of complexation, isomorphous substitution, and electrostatic attraction to the total adsorption amounts were 12.43%-37.89%, 6.35%-18.81%, and < 3.5%, respectively. For MgAl-LDH, the precipitation and complexation mechanisms accounted for 28.68%-52.71% and 18.12%-66.13%. After polyethylene glycol modification, the contributions of precipitation increased and the complexation decreased. The material characterizations and quantitative analyses of adsorption mechanisms provide theoretical guidance and foundation to further understand the interfacial sorption process, which is conducive to a deeper understanding of the removal mechanism of heavy metals.

Development of an apolipoprotein E mimetic peptide–lipid conjugate for efficient brain delivery of liposomes

Liposomes are versatile carriers that can encapsulate various drugs; however, for delivery to the brain, they must be modified with a targeting ligand or other modifications to provide blood–brain barrier (BBB) permeability, while avoiding rapid clearance by reticuloendothelial systems through polyethylene glycol (PEG) modification. BBB-penetrating peptides act as brain-targeting ligands. In this study, to achieve efficient brain delivery of liposomes, we screened the functionality of eight BBB-penetrating peptides reported previously, based on high-throughput quantitative evaluation methods with in vitro BBB permeability evaluation system using Transwell, in situ brain perfusion system, and others. For apolipoprotein E mimetic tandem dimer peptide (ApoEdp), which showed the best brain-targeting and BBB permeability in the comparative evaluation of eight peptides, its lipid conjugate with serine–glycine (SG)5 spacer (ApoEdp-SG-lipid) was newly synthesized and ApoEdp-modified PEGylated liposomes were prepared. ApoEdp-modified PEGylated liposomes were effectively associated with human brain capillary endothelial cells via the ApoEdp sequence and permeated the membrane in an in vitro BBB model. Moreover, ApoEdp-modified PEGylated liposomes accumulated in the brain 3.9-fold higher than PEGylated liposomes in mice. In addition, the ability of ApoEdp-modified PEGylated liposomes to localize beyond the BBB into the brain parenchyma in mice was demonstrated via three-dimensional imaging with tissue clearing. These results suggest that ApoEdp-SG-lipid modification is an effective approach for endowing PEGylated liposomes with the brain-targeting ability and BBB permeability.

Effect of polyethylene glycol modification on the corrosion behavior of hydroxyapatite-coated AZ31 Mg alloy under tensile deformation

The effect of polyethylene glycol (PEG) modification on the corrosion behavior under tensile deformation of hydroxyapatite-coated Mg-3mass% Al-1mass% Zn (HAp-AZ31) was examined in Hanks’ solution. Slow strain rate tensile (SSRT) and rapid straining electrode (RSE) tests and electrochemical impedance measurements were performed. In SSRT tests, PEG-modified HAp-AZ31 showed 1.4 times longer elongation to failure than HAp-AZ31. In RSE tests, the PEG modification showed little effect on cracking of HAp coating, while it reduced corrosion propagation from the cracks by half. The improvement in tensile elongation of HAp-AZ31 with PEG is attributed to the inhibition of corrosion propagation from coating cracks.

Layer Height, Temperature Nozzle, Infill Geometry and Printing Speed Effect on Accuracy 3D Printing PETG

The manufacturing industry has grown rapidly in the last few decades. 3D printing is one of the technologies of manufacturing, this technology makes products by adding filaments that are stacked systematically to become a finished product. PETG filament is a polymer with the name polyester but with glycol modification. This study aims to determine and understand the effect of the process parameters layer height, nozzle temperature, infill geometry and printing speed. This research method uses the Taguchi method with L16 and various parameters; layer height 0.12mm; 0.16mm; 0.2mm; 0.28mm, infill geometry cross; cubic; tri-hexagonal; triangles, nozzle temperature 220ºC; 230ºC; 240ºC; 250ºC and printing speed 40mm/s; 50mm/s; 60mm/s; 70mm/s. After testing, it can be concluded that the most influential parameters are sequentially; layer height, nozzle temperature, printing speed, and infill geometry with layer height parameters have the dominant influence, nozzle temperature and printing speed parameters have a balanced influence and infill geometry parameters have the least influence.

Polydopamine Copolymers for Stable Drug Nanoprecipitation.

Polydopamine (PDA), a biomaterial inspired by marine mussels, has attracted interest in cancer nanomedicine due to its photothermal properties, nanoparticle coating, and pi-pi stacking-based drug encapsulation abilities. Despite numerous one-pot and post-polymerization modifications, PDA copolymers have not been sufficiently studied in the context of stabilizing hydrophobic drugs in the process of nanoprecipitation. In this study, we tested combinatorial panels of comonomers with PDA to optimize drug loading efficiency, particle size and stability of nano formulations made via drug nanoprecipitation. As a selection criterion for optimal comonomers, we used drug aggregation-induced emission (AIE). We identified 1,1,2-Trimethyl-3-(4-sulfobutyl)benz[e]indolium (In820) as a novel and highly useful comonomer for catecholamines and optimized the conditions for its incorporation into PDA copolymers used for drug nanoprecipitation. Surprisingly, it was superior to polyethylene glycol modifications in every aspect. The leading copolymer, poly(dopamine)-poly(L-dopa)-co-In820 (PDA-PDO-In820 1:1:1), was shown to be a good stabilizer for several hydrophobic drugs. The resulting nanoparticles showed stability for up to 15 days, high encapsulation efficiency of at least 80%, low toxicity, and high antitumor efficacy in vitro. Nanoprecipitation of hydrophobic drugs can be greatly enhanced by the use of PDA copolymers containing In820, which are easy-to-prepare and highly effective stabilizers.

Advances of modified IL-2 molecules in drug development

Interleukin-2 (IL-2) is one of the most important regulators in immune system, as it plays an essential part both in immune activation and suppression. However, as the first immunotherapy drug approved for the treatment of cancer, IL-2 is limited in clinical application by the serious adverse reactions. The long-felt needs in clinical practice, including prolonged half-lives, T cell subset specificity, and toxicity reduction can be achieved by polyethylene glycol (PEG) modification, Fc fusing, or protein mutation of IL-2. NKTR-214, the most advanced IL-2 pathway-targeted agent in clinical development for oncology, shows exciting results in treatment of melanoma in combination with nivolumab. At the same time, many more other modified molecules against cancer and autoimmune diseases are being tested in clinical research, an exciting future lying ahead for IL-2 therapeutics.

Polyethylene glycol—modified nanoscale conjugated polymer for the photothermal therapy of lung cancer

Killing tumor cells efficiently with photothermal therapy remains a huge challenge. In this study, we successfully prepared a novel polymer with photothermal conversion capability via a condensation reaction, and then subjected it to Polyethylene glycol (PEG) modification and ultrasonic nanocrystalline treatment to make it suitable for in vivo photothermal therapy applications. The conjugated polymer demonstrated good biocompatibility and photothermal conversion ability and was shown in cell experiments to be effective in killing tumor cells after laser irradiation. In addition, the conjugated polymer-based photothermal therapy, guided by photoacoustic real-time imaging and mediated by laser irradiation, of a tumor-bearing mouse model could effectively inhibit the growth of tumor tissue and demonstrated good in vivo biosafety. Thus, photothermal therapy based on the conjugated polymer synthesized in this study provides a new idea and strategy for the treatment of lung cancer.

Role of Physicochemical Factors on the Efficacy and Safety of Lipid-Based Nanosystems as Potential Drug Carriers

The efficacy and safety are two challenging factors before trusting the lipid-based Nanosystems (LBNs) for diagnostic and therapeutic purposes. The aim of this paper is to evaluate the accessible in-vitro and in-vivo studies on the contribution of major physicochemical factors of LBNs for the effective and safe delivery of drugs and anticancer agents into the target site. These factors included lipid charge, particle size and size distribution, lipid composition and components, surface hydrophilicity and hydrophobicity, and surface coating. Here, reliable databases were searched for full-text, accessible and original articles to conduct this review. We included relevant studies since 1992, which were conducted on the development of LBNs for therapeutic and diagnostic purposes. Many studies have shown that using polyethylene glycol modification reduces the undesirable side effects and controls the efficacy and toxicity for in-vitro and in-vivo delivery of drugs or anticancer agents. Also, optimization of the size and composition of lipid nanoparticles minimizes the toxicity of the anticancer agents associated with a carrier. In addition, the presence of positively charged lipids in LBNs improves the efficacy of encapsulated drugs in spite of low blood circulation efficiency and high toxicity effects. The identification of important factors involved in the delivery of LBNs as potential drug carriers is crucial and contributes to the proper design of these interesting carriers for both therapeutic and diagnostic purposes.

A general in-situ reduction method to prepare core-shell liquid-metal / metal nanoparticles for photothermally enhanced catalytic cancer therapy

Gallium indium (GaIn) alloy as a kind of liquid metal (LM) with unique chemical and physical properties has attracted increasing attention for its potential biomedical applications. Herein, a series of core-shell GaIn@Metal (Metal: Pt, Au, Ag, and Cu) heterogeneous nanoparticles (NPs) are obtained by a simple in-situ reduction method. Take core-shell GaIn@Pt NPs for example, the synthesized GaIn@Pt NPs after Pt growth on their surface showed significantly improved photothermal conversion efficiency (PCE) and thermal stability under near-infrared (NIR) II light irradiation. Moreover, the core-shell GaIn@Pt NPs also exhibited good Fenton-like catalytic effect due to the presence of Pt on their surface, and could convert tumor endogenous H2O2 to generate reactive oxygen species (ROS) for cancer cell killing. With biocompatible polyethylene glycol (PEG) modification, such GaIn@Pt-PEG NPs showed efficient tumor homing after intravenous injection, and could lead to effective NIR II triggered photothermal-chemodynamic synergistic therapy of tumors as evidenced in a mouse tumor model. Our work highlights the ingenious use of the chemical properties of metals, providing a rather simple route for the surface engineering of LM-based multifunctional nanoplatforms to achieve a variety of functionalities.

Methoxy polyethylene glycol modification promotes adipogenesis by inducing the production of regulatory T cells in xenogeneic acellular adipose matrix.

Acellular adipose matrix (AAM) has emerged as an important biomaterial for adipose tissue regeneration. Current decellularization methods damage the bioactive components of the extracellular matrix (ECM), and the residual immunogenic antigens may induce adverse immune responses. Here, we adopted a modified decellularization method which can protect more bioactive components with less immune reaction by methoxy polyethylene glycol (mPEG). Then, we determined the adipogenic mechanisms of mPEG-modified AAM after xenogeneic transplantation. AAM transplantation caused significantly lesser adipogenesis in the wild-type group than in the immune-deficient group. The mPEG-modified AAM showed significantly lower immunogenicity and higher adipogenesis than the AAM alone after xenogeneic transplantation. Furthermore, mPEG modification increased regulatory T (Treg) cell numbers in the AAM grafts, which in turn enhanced the M2/M1 macrophage ratio by secreting IL-10, IL-13, and TGF-β1. These findings suggest that mPEG modification effectively reduces the immunogenicity of xenogeneic AAM and promotes adipogenesis in the AAM grafts. Hence, mPEG-modified AAM can serve as an ideal biomaterial for xenogeneic adipose tissue engineering.

Inhalable PLGA microspheres: Tunable lung retention and systemic exposure via polyethylene glycol modification

Polyethylene glycol (PEG) modification is one of the promising approaches to overcome both mucus and alveolar macrophage uptake barriers in the deep lung for sustained therapy of pulmonary diseases such as asthma. To investigate the feasibility of using PEG-modified microspheres to bypass both barriers, we prepared a collection of polyethylene glycol-distearoyl glycero-phosphoethanolamine (PEG-DSPE)-modified poly (lactide-co-glycolide) (PLGA) microspheres bearing specific PEG molecular weights (0.75, 2, 5, and 10 kDa) and PEG-DSPE/PLGA molar ratios (0.25:1 and 1:1). Drug release, mucus penetration, and macrophage uptake were evaluated in vitro, and the corresponding in vivo activities of microspheres in rats were investigated. It was found that the PEG2000-DSPE/PLGA 1:1 group showed enhanced mucus permeability and reduced macrophage uptake in vitro compared to the PEG2000-DSPE/PLGA 0.25:1 group. At high PEG molar ratios, only the PEG 2000-based group showed significantly prolonged lung retention in vivo compared to the control group. The systemic exposure of the PEG2000-DSPE/PLGA 1:1 group was significantly lower than that of the PEG2000-DSPE/PLGA 0.25:1 group (39% of AUC reduction). Additionally, when using the same molar ratio of 1:1, the PEG 2000 group significantly lowered the systemic drug exposure compared to that of the PEG 5000 and 10000 groups (48% and 33% of AUC reduction, respectively), thus making it a promising sustained lung delivery candidate for pulmonary disease treatment.

In Vivo Fluorescence Imaging of Passive Inflammation Site Accumulation of Liposomes via Intravenous Administration Focused on Their Surface Charge and PEG Modification.

Nanocarriers such as liposomes have been attracting attention as novel therapeutic methods for inflammatory autoimmune diseases such as rheumatoid arthritis and ulcerative colitis. The physicochemical properties of intravenously administered nanomedicines enable them to target inflamed tissues passively. However, few studies have attempted to determine the influences of nanoparticle surface characteristics on inflammation site accumulation. Here, we aimed to study the effects of polyethylene glycol (PEG) modification and surface charge on liposome ability to accumulate in inflammatory sites and be uptake by macrophages. Four different liposome samples with different PEG modification and surface charge were prepared. Liposome accumulation in the inflammation sites of arthritis and ulcerative colitis model mice was evaluated by using in vivo imaging. There was greater PEG-modified than unmodified liposome accumulation at all inflammation sites. There was greater anionic than cationic liposome accumulation at all inflammation sites. The order in which inflammation site accumulation was confirmed was PEG-anionic > PEG-cationic > anionic > cationic. PEG-anionic liposomes had ~2.5× higher fluorescence intensity than PEG-cationic liposomes, and the PEG-liposomes had ~2× higher fluorescence intensity than non-PEG liposomes. All liposomes have not accumulated at the inflammation sites in healthy mice. Furthermore, cationic liposomes were taken up to ~10× greater extent by RAW264.7 murine macrophages. Thus, PEG-cationic liposomes that have the ability to accumulate in inflammatory sites via intravenous administration and to be taken up by macrophages could be useful.

Superior anti-infective potential of eugenol-casein nanoparticles combined with polyethylene glycol against Colletotrichum musae infections.

The aim of this study was to improve the stability of eugenol–casein nanoparticles (EL–CS-NPs) through polyethylene glycol (PEG) modification. The results show that modifying the EL–CS-NPs with PEG after loading with eugenol (EL) gives PEG–EL–CS-NPs, with increased stability. The NPs modified with higher-molecular-weight PEG showed better stability. A CS/PEG ratio of 200 : 1 (w/w) yielded the NPs with the best stability. A PEG20 K–EL–CS-NP dispersion remained stable in cold storage for over one year, and also exhibited stronger inhibitory effects against Colletotrichum musae inoculated on bananas than an EL–CS-NP dispersion, since it showed more prolonged sustained release of EL than the EL–CS-NP dispersion. Lyophilized PEG20 K–EL–CS-NP powder showed better effectiveness against mold on bread than lyophilized EL–CS-NPs powder. Using PEG to modify CS-NPs shows potential for improving the stability of CS-NPs loaded with hydrophobic substances for delivery in the fields of food and agriculture.

An albumin-binding dimeric prodrug nanoparticle with long blood circulation and light-triggered drug release for chemo-photodynamic combination therapy against hypoxia-induced metastasis of lung cancer.

Photodynamic therapy (PDT) has been widely used in cancer therapy, but its therapeutic effect is reduced by the aggravating hypoxic microenvironment via upregulating hypoxia-associated proteins and promoting tumor metastasis. To mitigate these issues, we designed an albumin-binding and light-triggered core-shell dimeric prodrug nanoparticle to inhibit hypoxia-induced tumor metastasis and enhance the PDT efficacy. The prodrug nanoparticles, Ce6&DHA-S-DHA@CMN NPs (CDC NPs), were prepared using a single thioether-linked dihydroartemisinin (DHA) dimer co-encapsulated with Chlorin e6 (Ce6) and stabilized by albumin-capturing maleimide- and hypoxia-sensitive 2-nitroimidazole-modified carboxymethyl chitosan (CMCTS-MAL&NI, CMN for short). Upon laser irradiation, Ce6 could generate reactive oxygen species (ROS), which not only exerted the effect of the PDT but also broke the ROS-sensitive single thioether bridge in the dimeric prodrug DHA-S-DHA, thus accelerating the disassembly of the nanoparticles. DHA-S-DHA served as both an ROS-responsive carrier for Ce6 and a chemotherapeutic drug, synergizing with PDT and inhibiting tumor metastasis by downregulating hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF). Polyethylene glycol (PEG) modification has been widely used to stabilize hydrophobic prodrug nanoparticles and prolong the circulation time, but the PEGylated nanoparticles always suffer from accelerated blood clearance (ABC), a phenomenon which restricts their application severely. In this study, PEG was replaced by an amphipathic micelle, CMN, which could specifically capture albumin in the blood, conferring the nanoparticles long circulation and no ABC phenomenon. Under the aggravating hypoxic condition during PDT, the conversion of 2-nitroimidazole groups to 2-aminoimidazole groups in CMN could destabilize the structure of the shell and accelerate drug release. Results showed that the novel CDC NPs exhibited unique advantages in chemo-photodynamic combination therapy, such as long systemic circulation, high tumor accumulation, light-triggered drug release, HIF-1α/VEGF downregulation, and anti-metastasis efficacy, which provided a new route to overcome the ABC phenomenon of the PEGylated prodrug nanoparticles and reverse the hypoxia-induced metastasis simultaneously.

Improved chemical precipitation prepared rapidly NiCo2S4 with high specific capacitance for supercapacitors

In this work, rapid chemical precipitation assisted annealing method is used to prepare flower-like NiCo2S4. And the flower-like structure after polyethylene glycol (PEG) modification yields an excellent specific capacitance (2198.9 F g−1 at 1 A g−1). And an asymmetric supercapacitor assembled with NiCo2S4 (PEG-modified) and activated carbon (AC) shows an energy density of 38.2 Wh kg−1 at 400 W kg−1, and outstanding stability (80% remained after 3000 cycles at 5 A g−1). Benefited by a larger specific surface area and suitable pore size of the aggregate structure, the specific capacitance of prepared NiCo2S4 is increased by about 2 times. This uncomplicated preparation method is proved to be suitable for NiCo2S4 with a high specific capacitance of supercapacitors.

Pt-support interaction and nanoparticle size effect in Pt/CeO2–TiO2 catalysts for low temperature VOCs removal

A series of Pt/CeO2–TiO2 catalysts (0.5 wt% Pt) with size-controllable Pt nanoparticles were prepared by a modified ethylene glycol reduction method and the Pt particle size effect of Pt/CeO2–TiO2 catalysts on benzene and 1,2-dichloroethane (DCE) degradation was investigated. It reveals that the metal-support interaction of PtOx species and CeO2–TiO2 mixed oxides is enhanced by the reduced Pt particle sizes. The formation of more Pt2+ species and stronger redox properties at low-temperature resulted by the enhanced metal-support interaction of Pt/CeO2–TiO2 catalysts both greatly promotes the deep oxidation for benzene and C2H3Cl byproduct during DCE degradation at low temperature. Pt/CeTi-11 with the smallest average Pt particle size (1.53 nm) exhibits the highest activity among all the catalysts for benzene degradation, with T90% of only 152 °C (1000 ppm, GHSV = 15,000 h−1). However, more acidic sites (especially the strong acid) were formed on the Pt/CeO2–TiO2 catalysts with bigger Pt nanoparticle (>2.95 nm), contributing to activate and convert DCE to C2H3Cl. More importantly, Pt/CeO2–TiO2 catalysts are extremely stable in DCE degradation reaction, and have been scarcely influenced by the presence of benzene and water in the feed gases.

Ultrasmall Iron-Doped Titanium Oxide Nanodots for Enhanced Sonodynamic and Chemodynamic Cancer Therapy.

Sonodynamic therapy (SDT), which can generate reactive oxygen species (ROS) based on sonosensitizers under ultrasound (US) to kill tumor cells, has emerged as a noninvasive therapeutic modality with high tissue-penetration depth. Herein, ultrasmall iron-doped titanium oxide nanodots (Fe-TiO2 NDs) are synthesized via a thermal decomposition strategy as a type of sonosensitizers to enhance SDT. Interestingly, the Fe doping in this system appears to be crucial in not only enhancing the US-triggered ROS generation of those NDs but also offering NDs the Fenton-catalytic function to generate ROS from tumor endogenous H2O2 for chemodynamic therapy (CDT). After polyethylene glycol (PEG) modification, Fe-TiO2-PEG NDs demonstrate good physiological stability and biocompatibility. With efficient tumor retention after intravenous injection as revealed by in vivo magnetic resonance (MR) and fluorescent imaging, our Fe-TiO2 NDs demonstrate much better in vivo therapeutic performance than commercial TiO2 nanoparticles owing to the combination of CDT and SDT. Moreover, most of those ultrasmall Fe-TiO2 NDs can be effectively excreted within one month, rendering no obvious long-term toxicity to the treated mice. Our work thus presents a type of multifunctional sonosensitizer for highly efficient cancer treatment via simply doping TiO2 nanostructures with metal ions.

Thioether-terminated triazole-bridged covalent organic framework for dual-sensitive drug delivery application

A novel thioether-terminated triazole bridge-containing covalent organic framework (TCOF) was constructed via a simple click chemistry between alkyne and azide monomers for dual-sensitive [pH and glutathione (GSH)] anticancer drug delivery systems. The synthesized TCOFs were crystalline in nature with a pore size of approximately 10–30 nm, as confirmed by powder X-ray diffraction spectroscopy and Brunauer–Emmett–Teller technique. Owing to the flexible nature of the synthesized COF, polyethylene glycol (PEG) modification was easily performed to yield a stable TCOF (TCOF-PEG) colloidal solution. Doxorubicin (DOX)-loaded TCOF-PEG (TCOF-DOX-PEG) exhibited sensitivity to lysosomal pH 5 and GSH environments. DOX release was four times higher under GSH environment (relative to pH 7.4) and three times higher under pH 5 condition because of the dynamic nature of triazole. In contrast, DOX-loaded COF without the triazole ring (I-COF) did not show any significant drug release in pH 7.4 and acidic pH; however, drug release was observed in GSH environment. MTT drug internalization data demonstrated sustained release of DOX from TCOF-DOX-PEGs. Finally, we demonstrated the utility of TCOF-PEG as an in vitro drug delivery system in HeLa cells. TCOF-DOX-PEG exhibited time-dependent release of DOX followed by internalization. Thus, the novel TCOF system reported here opens a new window in COF research for sensitive drug carrier systems.

PEG-modified lipase immobilized onto NH2-MIL-53 MOF for efficient resolution of 4-fluoromandelic acid enantiomers

A new heterogeneous bio-catalyst was prepared by the immobilization of lipase from Pseudomonas fluorescents (PFL) onto metal-organic frameworks (MOF), NH2-MIL-53(Fe), using covalent cross-linking. The immobilized lipase [PEG-PFL@NH2-MIL-53(Fe)] was firstly applied in enantioselective resolution of 4-fluoromandelic acid (4-FMA) enantiomers. After optimization of the immobilization PFL onto NH2-MIL-53, its loading capacity is 224.5 mg PFL/g MOF. The optimal enzymatic conditions are temperature of 50 °C, VA/4-FMA substrate ratio of 6:1, immobilized lipase loading of 60 mg and reaction time of 12 h. Experimental results show that the catalytic activity and thermal stability of PFL are significantly improved by polyethylene glycol (PEG) modification and immobilization. At 65 °C, the catalytic activity of immobilized lipase retains 86.0% of initial activity. Under the optimal conditions, the excellent results were obtained with conversion of 49.6% and enantiomer excess of 98.0% for the immobilized PFL catalyzed transesterification reaction. Furthermore, the immobilized lipase exhibits excellent cycle stability with 83% of its initial activity after four cycle.

Carboxylated ε-poly-L-lysine, a cryoprotective agent, is an effective partner of ethylene glycol for the vitrification of embryos at various preimplantation stages

It has been known that different protocols are used for embryo preservation at different stages due to different sensitivity to the physical and physiological stress caused by vitrification. In this study, we developed a common vitrification protocol using carboxlated ε-poly-l-lysine (COOH-PLL), a new cryoprotective agent for the vitrification of mouse embryos at different stages. The IVF-derived Crl:CD1(ICR) x B6D2F1/Crl pronuclear, 2-cell, 4-cell, and 8-cell, morula and blastocyst stage embryos were vitrified with 15% (v/v) ethylene glycol (EG) and 10% (w/v) COOH-PLL (E15P15) or 15% (v/v) EG and 15% (v/v) dimethyl sulfoxide (E15D15) using the minimal volume cooling method. The survival of vitrified embryos from pronuclear to blastocyst stages was equivalent between E15P15 and E15D15 groups. However, the rate of development to blastocysts was significantly lower in E15P15 than E15D15. The rates of survival and development to blastocysts were dramatically improved by a slight modification of EG and COOH-PLL concentrations (E20P10). After transferring 17 (E20P10) and 15 (E15D15) vitrified/warmed blastocysts, 8 and 7 pups were obtained (47.1% and 46.7%, respectively). Taken together, these results indicate that our vitrification protocol is appropriate for the vitrification of mouse embryos at different stages.