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IScience Apr 2023Physical mechanisms of phase separation in living systems play key physiological roles and have recently been the focus of intensive studies. The strongly heterogeneous...
Physical mechanisms of phase separation in living systems play key physiological roles and have recently been the focus of intensive studies. The strongly heterogeneous nature of such phenomena poses difficult modeling challenges that require going beyond mean-field approaches based on postulating a free energy landscape. The pathway we take here is to calculate the partition function starting from microscopic interactions by means of cavity methods, based on a tree approximation for the interaction graph. We illustrate them on the binary case and then apply them successfully to ternary systems, in which simpler one-factor approximations are proved inadequate. We demonstrate the agreement with lattice simulations and contrast our theory with coacervation experiments of associative de-mixing of nucleotides and poly-lysine. Different types of evidence are provided to support cavity methods as ideal tools for modeling biomolecular condensation, giving an optimal balance between the consideration of spatial aspects and fast computational results.
PubMed: 36994084
DOI: 10.1016/j.isci.2023.106300 -
International Journal of Molecular... Mar 2023Polyethylene--polypeptide copolymers are biologically interesting, but studies of their synthesis and properties are very few. This paper reports synthesis and...
Polyethylene--polypeptide copolymers are biologically interesting, but studies of their synthesis and properties are very few. This paper reports synthesis and characterization of well-defined amphiphilic polyethylene--poly(L-lysine) (PE--PLL) block copolymers by combining nickel-catalyzed living ethylene polymerization with controlled ring-opening polymerization (ROP) of ε-benzyloxycarbonyl-L-lysine--carboxyanhydride (Z-Lys-NCA) and sequential post-functionalization. Amphiphilic PE--PLL block copolymers self-assembled into spherical micelles with a hydrophobic PE core in aqueous solution. The pH and ionic responsivities of PE--PLL polymeric micelles were investigated by means of fluorescence spectroscopy, dynamic light scattering, UV-circular dichroism, and transmission electron microscopy. The variation of pH values led to the conformational alteration of PLL from α-helix to coil, thereby changing the micelle dimensions.
Topics: Micelles; Polylysine; Polyethylene; Polymers; Peptides; Polyethylene Glycols
PubMed: 36982576
DOI: 10.3390/ijms24065495 -
Food Chemistry: X Mar 2023There are several problems with common starch films, including strong water absorption and poor mechanical properties. To create a better starch film, octenyl succinate...
There are several problems with common starch films, including strong water absorption and poor mechanical properties. To create a better starch film, octenyl succinate cassava starch ester (OSCS) was first blended with chitosan and nano ZnO to prepare an OSCS/CS/ZnO film. Then, the film was supplemented with different concentrations of ε-PL as a bacteriostatic agent to prepare a film that would resist bacterial invasion. The mechanical properties, barrier properties, optical properties, and color of the modified starch antibacterial films were investigated, and finally the antibacterial properties and cytotoxicity were tested. The results demonstrated that the modified starch antibacterial film had good mechanical properties, improved surface hydrophobicity, and had a UV-blocking effect. The modified starch antibacterial film with ε-PL of 8% had stable and long-lasting antibacterial properties, stable release, and good cytocompatibility. An active packaging material was successfully prepared using ε-PL and had a strong preservative effect on food.
PubMed: 36974189
DOI: 10.1016/j.fochx.2023.100602 -
Cytotechnology Apr 2023β-Conglycinin was conjugated with ε-polylysine (PL) by means of microbial transglutaminase (MTGase) to improve its function. The β-conglycinin-PL conjugate was...
β-Conglycinin was conjugated with ε-polylysine (PL) by means of microbial transglutaminase (MTGase) to improve its function. The β-conglycinin-PL conjugate was purified by dialysis. Composition of the β-conglycinin-PL was β-conglycinin:PL = 1:18 (molar ratio) which was confirmed by amino acid analysis. The β-conglycinin-PL was further conjugated with dextran (Dex) by the Maillard reaction. The β-conglycinin-PL-Dex conjugate was purified by dialysis. Conjugation was confirmed by SDS-PAGE and PAS staining. Composition of the β-conglycinin-PL-Dex was β-conglycinin-PL:Dex = 1:41 (molar ratio) which was confirmed by UV spectra measurement and phenol sulfuric acid method. Solubility of β-conglycinin in the acidic range was much improved by conjugation with PL and further improved by further conjugation with Dex. Emulsifying property of β-conglycinin in acidic pH range was much improved by conjugation with PL and Dex. Immunogenicity of β-conglycinin was decreased by conjugation with PL and Dex.
PubMed: 36969573
DOI: 10.1007/s10616-022-00568-6 -
Microbial Cell Factories Mar 2023ε-Poly-L-lysine (ε-PL) is a natural and safe food preservative that is mainly produced by filamentous and aerobic bacteria Streptomyces albulus. During ε-PL...
BACKGROUND
ε-Poly-L-lysine (ε-PL) is a natural and safe food preservative that is mainly produced by filamentous and aerobic bacteria Streptomyces albulus. During ε-PL biosynthesis, a large amount of ATP is used for the polymerization of L-lysine. A shortage of intracellular ATP is one of the major factors limiting the increase in ε-PL production. In previous studies, researchers have mainly tried to increase the oxygen supply to enhance intracellular ATP levels to improve ε-PL production, which can be achieved through the use of two-stage dissolved oxygen control, oxygen carriers, heterologous expression of hemoglobin, and supplementation with auxiliary energy substrates. However, the enhancement of the intracellular ATP supply by constructing an ATP regeneration system has not yet been considered.
RESULTS
In this study, a polyphosphate kinase (PPK)-mediated ATP regeneration system was developed and introduced into S. albulus to successfully improve ε-PL production. First, polyP:AMP phosphotransferase (PAP) from Acinetobacter johnsonii was selected for catalyzing the conversion of AMP into ADP through an in vivo test. Moreover, three PPKs from different microbes were compared by in vitro and in vivo studies with respect to catalytic activity and polyphosphate (polyP) preference, and PPK2B from Corynebacterium glutamicum was used for catalyzing the conversion of ADP into ATP. As a result, a recombinant strain PL05 carrying coexpressed pap and ppk2B for catalyzing the conversion of AMP into ATP was constructed. ε-PL production of 2.34 g/L was achieved in shake-flask fermentation, which was an increase of 21.24% compared with S. albulus WG608; intracellular ATP was also increased by 71.56%. In addition, we attempted to develop a dynamic ATP regulation route, but the result was not as expected. Finally, the conditions of polyP addition were optimized in batch and fed-batch fermentations, and the maximum ε-PL production of strain PL05 in a 5-L fermenter was 59.25 g/L by fed-batch fermentation, which is the highest ε-PL production reported in genetically engineered strains.
CONCLUSIONS
In this study, we proposed and developed a PPK-mediated ATP regeneration system in S. albulus for the first time and significantly enhanced ε-PL production. The study provides an efficient approach to improve the production of not only ε-PL but also other ATP-driven metabolites.
Topics: Polylysine; Fermentation; Adenosine Triphosphate; Regeneration
PubMed: 36918890
DOI: 10.1186/s12934-023-02057-7 -
Journal of Food Protection Mar 2023Biofilm formation of Listeria monocytogenes in food processing environments cause potential source of cross-contamination to foodstuffs; hence, the control of biofilm is...
Biofilm formation of Listeria monocytogenes in food processing environments cause potential source of cross-contamination to foodstuffs; hence, the control of biofilm is currently addressed to find effective solutions for preventing biofilm formation or eliminating the established one. Forty-five strains of Listeria monocytogenes isolated from Pangasius fish-processing plants were studied for their capability to form a biofilm on 96-well microtiter plate by using the conventional crystal violet staining. Additionally, the inhibitory effect of biofilm formation by food additives including monascus pigment and ε-polylysine was examined. The average OD value showing biofilm mass of all 45 strains L. monocytogenes increased with an increasing temperature and time (p < 0.05). Monascus pigment and ε-polylysine significantly decreased biofilm formation by 80 ± 5.5% and 20 ± 5.9%, respectively, at the tested concentration (p < 0.05) Further, the effects of lysozyme (0.1 mg/mL) alone or in combination with slightly acidic hypochlorous water (SAHW) with 40 mg/L available chlorine or sodium hypochlorite (NaOCl) with 100 mg/L available chlorine against 7-d established biofilm of L. monocytogenes were investigated. The results indicated that slightly acidic hypochlorous water alone exhibited significant antibacterial activity (p < 0.05), decreasing the viable count by 5.2 ± 0.5 log CFU/mL. It seems that sequential treatment of lysozyme and SAHW showed an additional efficacy against biofilm of L. monocytogenes on polystyrene plate surface, reducing 70% of biomass of biofilm and 7.6 ± 0.3 log of biofilm viable cells (p < 0.05). Additionally, SAHW exhibited greater bactericidal activity against viable biofilm cells than NaOCl did. This result reveals that SAHW is a promising disinfectant agent against L. monocytogenes and the potential alternative to NaOCl in practice.
Topics: Animals; Listeria monocytogenes; Muramidase; Chlorine; Polylysine; Stainless Steel; Biofilms; Catfishes; Water; Colony Count, Microbial
PubMed: 36916551
DOI: 10.1016/j.jfp.2023.100044 -
Bioresources and Bioprocessing 2023Mesenchymal stem cells (MSCs) are highly important in biomedicine and hold great potential in clinical treatment for various diseases. In recent years, the capabilities...
UNLABELLED
Mesenchymal stem cells (MSCs) are highly important in biomedicine and hold great potential in clinical treatment for various diseases. In recent years, the capabilities of MSCs have been under extensive investigation for practical application. Regarding therapy, the efficacy usually depends on the amount of MSCs. Nevertheless, the yield of MSCs is still limited due to the traditional cultural methods. Herein, we proposed a three-dimensional (3D) scaffold prepared using poly lactic-co-glycolic acid (PLGA) nanofiber with polylysine (PLL) grafting, to promote the growth and proliferation of MSCs derived from the human umbilical cord (hUC-MSCs). We found that the inoculated hUC-MSCs adhered efficiently to the PLGA scaffold with good affinity, fast growth rate, and good multipotency. The harvested cells were ideally distributed on the scaffold and we were able to gain a larger yield than the traditional culturing methods under the same condition. Thus, our cell seeding with a 3D scaffold could serve as a promising strategy for cell proliferation in the large-scale production of MSCs. Moreover, the simplicity and low preparation cost allow this 3D scaffold to extend its potential application beyond cell culture.
SUPPLEMENTARY INFORMATION
The online version contains supplementary material available at 10.1186/s40643-023-00635-6.
PubMed: 36915643
DOI: 10.1186/s40643-023-00635-6 -
Journal of Thrombosis and Haemostasis :... Jun 2023Hemorrhage, in particular noncompressible hemorrhage, is the leading cause of casualties in combat trauma and civilian trauma. Although systemic agents can stop bleeding...
An anticoagulant/procoagulant self-converting and bleeding site-targeting systemic nanotherapy for rapidly controlling noncompressible bleeding without risk of thrombosis.
BACKGROUND
Hemorrhage, in particular noncompressible hemorrhage, is the leading cause of casualties in combat trauma and civilian trauma. Although systemic agents can stop bleeding at both inaccessible and accessible injury sites, the application of systemic hemostats in clinics is strictly limited by the nontargeting ability of hemostats and their subsequent potential for thromboembolic complications.
OBJECTIVES
To engineer an anticoagulant/procoagulant self-converting and bleeding site-targeting systemic nanohemostat to rapidly control noncompressible bleeding without thrombosis risk.
METHODS
A multiscale computer simulation was taken to guide the self-assembly of sulindac (SUL, a prodrug of the antiplatelets agent) and poly-L-lysine (a cation polymer with platelets activation ability) for forming poly-L-lysine/SUL nanoparticles (PSNs). In vitro platelet-adhering ability, platelet activation effect, and hemostasis activity of PSNs were evaluated. Then, the biosafety, level of thrombosis, targeting ability, and hemostasis effect of systemic applied PSNs were carefully evaluated in various hemorrhage models.
RESULTS
PSNs were successfully prepared and showed good platelet adhesion and activation in vitro. The bleeding site-targeting ability and hemostatic efficiency in different bleeding models were leveled up by PSNs markedly compared with vitamin K and etamsylate in vivo. SUL in PSNs could be metabolized into sulindac sulfide at clot sites in 4 hours for antiplatelet aggregation, thus reducing thrombotic risk compared with other hemostatic agents, via the ingenious utilization of prodrug metabolism in terms of time intervals and the adhesion on platelets.
CONCLUSION
PSNs are expected to be a low-cost, safe, efficient, clinically translatable first-aid hemostat for first-aid scenarios.
Topics: Humans; Anticoagulants; Computer Simulation; Polylysine; Prodrugs; Hemorrhage; Hemostasis; Hemostatics; Thrombosis
PubMed: 36871669
DOI: 10.1016/j.jtha.2023.02.020 -
Bioactive Materials Jul 2023Current treatments for full-thickness skin injuries are still unsatisfactory due to the lack of hierarchically stimulated dressings that can integrate the rapid...
Current treatments for full-thickness skin injuries are still unsatisfactory due to the lack of hierarchically stimulated dressings that can integrate the rapid hemostasis, inflammation regulation, and skin tissue remodeling into the one system instead of single-stage boosting. In this work, a multilayer-structured bioactive glass nanopowder (BGN@PTE) is developed by coating the poly-tannic acid and ε-polylysine onto the BGN facile layer-by-layer assembly as an integrative and multilevel dressing for the sequential management of wounds. In comparison to BGN and poly-tannic acid coated BGN, BGN@PTE exhibited the better hemostatic performance because of its multiple dependent approaches to induce the platelet adhesion/activation, red blood cells (RBCs) aggregation and fibrin network formation. Simultaneously, the bioactive ions from BGN facilitate the regulation of the inflammatory response while the poly-tannic acid and antibacterial ε-polylysine prevent the wound infection, promoting the wound healing during the inflammatory stage. In addition, BGN@PTE can serve as a reactive oxygen species scavenger, alleviate the oxidation stress in wound injury, induce the cell migration and angiogenesis, and promote the proliferation stage of wound repair. Therefore, BGN@PTE demonstrated the significantly higher wound repair capacity than the commercial bioglass dressing Dermlin™. This multifunctional BGN@PTE is a potentially valuable dressing for full-thickness wound management and may be expected to extend to the other wounds therapy.
PubMed: 36844363
DOI: 10.1016/j.bioactmat.2023.01.019 -
Biomimetics (Basel, Switzerland) Jan 2023Microneedles (MNs) have attracted great interest as a drug delivery alternative to subcutaneous injections for treating diabetes mellitus. We report MNs prepared from...
Microneedles (MNs) have attracted great interest as a drug delivery alternative to subcutaneous injections for treating diabetes mellitus. We report MNs prepared from polylysine-modified cationized silk fibroin (SF) for responsive transdermal insulin delivery. Scanning electron microscopy analysis of MNs' appearance and morphology revealed that the MNs were well arranged and formed an array with 0.5 mm pitch, and the length of single MNs is approximately 430 μm. The average breaking force of an MN is above 1.25 N, which guarantees that it can pierce the skin quickly and reach the dermis. Cationized SF MNs are pH-responsive. MNs dissolution rate increases as pH decreases and the rate of insulin release are accelerated. The swelling rate reached 223% at pH = 4, while only 172% at pH = 9. After adding glucose oxidase, cationized SF MNs are glucose-responsive. As the glucose concentration increases, the pH inside the MNs decreases, the MNs' pore size increases, and the insulin release rate accelerates. In vivo experiments demonstrated that in normal Sprague Dawley (SD) rats, the amount of insulin released within the SF MNs was significantly smaller than that in diabetic rats. Before feeding, the blood glucose (BG) of diabetic rats in the injection group decreased rapidly to 6.9 mmol/L, and the diabetic rats in the patch group gradually reduced to 11.7 mmol/L. After feeding, the BG of diabetic rats in the injection group increased rapidly to 33.1 mmol/L and decreased slowly, while the diabetic rats in the patch group increased first to 21.7 mmol/L and then decreased to 15.3 mmol/L at 6 h. This demonstrated that the insulin inside the microneedle was released as the blood glucose concentration increased. Cationized SF MNs are expected to replace subcutaneous injections of insulin as a new modality for diabetes treatment.
PubMed: 36810381
DOI: 10.3390/biomimetics8010050