Biodegradable Polypeptide-based Vesicles with Intrinsic Blue Fluorescence for Antibacterial Visualization

From dansyl-modified biofilm disruptors to β-cyclodextrin-optimized multifunctional supramolecular nanovesicles: their improved treatment for plant bacterial diseases

BACKGROUND

Bacterial diseases caused by phytopathogenic Xanthomonas pose a significant threat to global agricultural production, causing substantial economic losses. Biofilm formation by these bacteria enhances their resistance to environmental stressors and chemical treatments, complicating disease control. The key to overcoming this challenge lies in the development of multifunctional green bactericides capable of effectively breaking down biofilm barriers, improving foliar deposition properties, and achieving the control of bacterial diseases.

RESULTS

We have developed a kind of innovative green bactericide from small-molecule conception to eco-friendly supramolecular nanovesicles (DaPA8@β -CD) by host-guest supramolecular technology. These nanoscale assemblies demonstrated the ability to inhibit and eradicate biofilm formation, while also promoted foliar wetting and effective deposition properties, laying the foundation for improving agrochemical utilization. Studies revealed that DaPA8@β -CD exhibited significant biofilm inhibition (78.66% at 7.0 µ g mL- 1) and eradication (83.50% at 25.0 µ g mL- 1), outperforming DaPA8 alone (inhibition: 59.71%, eradication: 66.79%). These nanovesicles also reduced exopolysaccharide formation and bacterial virulence. In vivo experiments showed enhanced control efficiency against citrus bacterial canker (protective: 78.04%, curative: 50.80%) at a low dose of 200 µ g mL- 1, superior to thiodiazole-copper-20%SC and DaPA8 itself.

CONCLUSION

This study demonstrates the potential of DaPA8@β -CD nanovesicles as multifunctional bactericides for managing Xanthomonas -induced plant diseases, highlighting the advantages of using host-guest supramolecular technology to enhance agrochemical bioavailability.

Advancing Artificial Cells with Functional Compartmentalized Polymeric Systems - In Honor of Wolfgang Meier

The fundamental building block of living organisms is the cell, which is the universal biological base of all living entities. This micrometric mass of cytoplasm and the membrane border have fascinated scientists due to the highly complex and multicompartmentalized structure. This specific organization enables numerous metabolic reactions to occur simultaneously and in segregated spaces, without disturbing each other, but with a promotion of inter- and intracellular communication of biomolecules. At present, artificial nano- and microcompartments, whether as single components or self-organized in multicompartment architectures, hold significant value in the study of life development and advanced functional materials and in the fabrication of molecular devices for medical applications. These artificial compartments also possess the properties to encapsulate, protect, and control the release of bio(macro)molecules through selective transport processes, and they are capable of embedding or being connected with other types of compartments. The self-assembly mechanism of specific synthetic compartments and thus the fabrication of a simulated organelle membrane are some of the major aspects to gain insight. Considerable efforts have now been devoted to design various nano- and microcompartments and understand their functionality for precise control over properties. Of particular interest is the use of polymeric vesicles for communication in synthetic cells and colloidal systems to reinitiate chemical and biological communication and thus close the gap toward biological functions. Multicompartment systems can now be effectively created with a high level of hierarchical control. In this way, these structures can not only be explored to deepen our understanding of the functional organization of living cells, but also pave the way for many more exciting developments in the biomedical field.

Emerging polymeric materials for treatment of oral diseases: design strategy towards a unique oral environment

Oral diseases are prevalent but challenging diseases owing to the highly movable and wet, microbial and inflammatory environment. Polymeric materials are regarded as one of the most promising biomaterials due to their good compatibility, facile preparation, and flexible design to obtain multifunctionality. Therefore, a variety of strategies have been employed to develop materials with improved therapeutic efficacy by overcoming physicobiological barriers in oral diseases. In this review, we summarize the design strategies of polymeric biomaterials for the treatment of oral diseases. First, we present the unique oral environment including highly movable and wet, microbial and inflammatory environment, which hinders the effective treatment of oral diseases. Second, a series of strategies for designing polymeric materials towards such a unique oral environment are highlighted. For example, multifunctional polymeric materials are armed with wet-adhesive, antimicrobial, and anti-inflammatory functions through advanced chemistry and nanotechnology to effectively treat oral diseases. These are achieved by designing wet-adhesive polymers modified with hydroxy, amine, quinone, and aldehyde groups to provide strong wet-adhesion through hydrogen and covalent bonding, and electrostatic and hydrophobic interactions, by developing antimicrobial polymers including cationic polymers, antimicrobial peptides, and antibiotic-conjugated polymers, and by synthesizing anti-inflammatory polymers with phenolic hydroxy and cysteine groups that function as immunomodulators and electron donors to reactive oxygen species to reduce inflammation. Third, various delivery systems with strong wet-adhesion and enhanced mucosa and biofilm penetration capabilities, such as nanoparticles, hydrogels, patches, and microneedles, are constructed for delivery of antibiotics, immunomodulators, and antioxidants to achieve therapeutic efficacy. Finally, we provide insights into challenges and future development of polymeric materials for oral diseases with promise for clinical translation.

Robust and Multifunctional Therapeutic Nanoparticles against Peritonitis-Induced Sepsis

Apart from bacterial growth and endotoxin generation, the excessive production of reactive radicals linked with sepsis also has a substantial impact on triggering an inflammatory response and further treatment failure. Hence, the rational design and fabrication of robust and multifunctional nanoparticles (NPs) present a viable means of overcoming this dilemma. In this study, we used antibiotic polymyxin B (PMB) and antioxidant natural polyphenolic protocatechualdehyde (PCA) to construct robust and multifunctional NPs for sepsis treatment, leveraging the rich chemistries of PCA. The PMB release profile from the NPs demonstrated pH-responsive behavior, which allowed the NPs to exhibit effective bacterial killing and radical scavenging properties. Data from in vitro cells stimulated with H2O2 and lipopolysaccharide (LPS) showed the multifunctionalities of NPs, including intracellular reactive oxygen species (ROS) scavenging, elimination of the bacterial toxin LPS, inhibiting macrophage M1 polarization, and anti-inflammation capabilities. Additionally, in vivo studies further demonstrated that NPs could increase the effectiveness of sepsis treatment by lowering the bacterial survival ratio, the expression of the oxidative marker malondialdehyde (MDA), and the expression of inflammatory cytokine TNF-α. Overall, this work provides ideas of using those robust and multifunctional therapeutic NPs toward enhanced sepsis therapy efficiency.

Physically and Chemically Compartmentalized Polymersomes for Programmed Delivery and Biological Applications

Multicompartment polymersomes (MCPs) refer to polymersomes that not only contain one single compartment, either in the membrane or in the internal cavity, but also mimic the compartmentalized structure of living cells, attracting much attention in programmed delivery and biological applications. The investigation of MCPs may promote the application of soft nanomaterials in biomedicine. This Review seeks to highlight the recent advances of the design principles, synthetic strategies, and biomedical applications of MCPs. The compartmentalization types including chemical, physical, and hybrid compartmentalization are discussed. Subsequently, the design and controlled synthesis of MCPs by the self-assembly of amphiphilic polymers, double emulsification, coprecipitation, microfluidics and particle assembly, etc. are summarized. Furthermore, the diverse applications of MCPs in programmed delivery of various cargoes and biological applications including cancer therapy, antimicrobials, and regulation of blood glucose levels are highlighted. Finally, future perspectives of MCPs from the aspects of controlled synthesis and applications are proposed.

Membrane and Lumen-Compartmentalized Polymersomes for Biocatalysis and Cell Mimics

Compartmentalization is a crucial feature of a natural cell, manifested in cell membrane and inner lumen. Inspired by the cellular structure, multicompartment polymersomes (MCPs), including membrane-compartmentalized polymersomes and lumen-compartmentalized polymersomes (polymersomes-in-polymersomes), have aroused great expectations for biological applications such as biocatalysis and cell mimics in the past decades. Compared with traditional polymersomes, MCPs have advantages in encapsulating multiple enzymes separately for multistep enzymatic cascade reactions. In this review, first, the design principles and preparation methods of membrane-compartmentalized and lumen-compartmentalized polymersomes are summarized. Next, recent advances of MCPs as nanoreactors and cell mimics to mimic subcellular organelles or artificial cells are discussed. Finally, the future research directions of MCPs are prospected.

In situ forming double-crosslinked hydrogels with highly dispersed short fibers for the treatment of irregular wounds

In situ forming injectable hydrogels hold great potential for the treatment of irregular wounds. However, their practical applications were hindered by long gelation time, poor mechanical performance, and a lack of a natural extracellular matrix structure. Herein, amino-modified electrospun poly(lactic-co-glycolic acid) (APLGA) short fibers with uniform distribution were introduced into gelatin methacrylate/oxidized dextran (GM/ODex) hydrogels. In comparison with the fiber aggregation structure in the PLGA fiber-incorporated hydrogels, the hydrogels with APLGA fibers possessed a uniform porous structure. The highly dispersed APLGA short fibers accelerated the sol-gel phase transition of the hydrogel due to the formation of dynamic Schiff-base bonds between the fibers and hydrogels. Furthermore, in combination with UV-assisted crosslinking, a rapid gelation time of 90 s was achieved for the double-crosslinked hydrogels. The addition of APLGA short fibers as fillers and the formation of the double-crosslinking network enhanced the mechanical performance of the hydrogels. Furthermore, the fiber-hydrogel composites exhibited favorable injectability, excellent biocompatibility, and improved cell infiltration. In vivo assessment indicated that the GM/ODex-APLGA hydrogels successfully filled the full-thickness defects and improved wound healing. This work demonstrates a promising solution for the treatment of irregular wounds.

Bio-Inspired Drug Delivery Systems: From Synthetic Polypeptide Vesicles to Outer Membrane Vesicles

Nanomedicine is a broad field that focuses on the development of nanocarriers to deliver specific drugs to targeted sites. A synthetic polypeptide is a kind of biomaterial composed of repeating amino acid units that are linked by peptide bonds. The multiplied amphiphilicity segment of the polypeptide could assemble to form polypeptide vesicles (PVs) under suitable conditions. Different from polypeptide vesicles, outer membrane vesicles (OMVs) are spherical buds of the outer membrane filled with periplasmic content, which commonly originate from Gram-negative bacteria. Owing to their biodegradability and excellent biocompatibility, both PVs and OMVs have been utilized as carriers in delivering drugs. In this review, we discuss the recent drug delivery research based on PVs and OMVs. These related topics are presented: (1) a brief introduction to the production methods for PVs and OMVs; (2) a thorough explanation of PV- and OMV-related applications in drug delivery including the vesicle design and biological assessment; (3) finally, we conclude with a discussion on perspectives and future challenges related to the drug delivery systems of PVs and OMVs.

Current Perspectives on Synthetic Compartments for Biomedical Applications

Nano- and micrometer-sized compartments composed of synthetic polymers are designed to mimic spatial and temporal divisions found in nature. Self-assembly of polymers into compartments such as polymersomes, giant unilamellar vesicles (GUVs), layer-by-layer (LbL) capsules, capsosomes, or polyion complex vesicles (PICsomes) allows for the separation of defined environments from the exterior. These compartments can be further engineered through the incorporation of (bio)molecules within the lumen or into the membrane, while the membrane can be decorated with functional moieties to produce catalytic compartments with defined structures and functions. Nanometer-sized compartments are used for imaging, theranostic, and therapeutic applications as a more mechanically stable alternative to liposomes, and through the encapsulation of catalytic molecules, i.e., enzymes, catalytic compartments can localize and act in vivo. On the micrometer scale, such biohybrid systems are used to encapsulate model proteins and form multicompartmentalized structures through the combination of multiple compartments, reaching closer to the creation of artificial organelles and cells. Significant progress in therapeutic applications and modeling strategies has been achieved through both the creation of polymers with tailored properties and functionalizations and novel techniques for their assembly.

Photosensitizer-Polypeptides Conjugate with Synergistic Antibacterial Efficacy

Recently, continuous emergence of resistant bacteria has appeared as one of the most serious threats to human health. Therefore, systematic exploration of new antibacterial materials is of guiding significance. In this study, a series of photosensitizer-polypeptides conjugate (PPa-cP) was readily synthesized through the simple ring-opening reactions to realize the synergistic antibacterial effects toward Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA) under light irradiation. Compared with free PPa, the cationic PPa-cP showed enhanced binding ability with the negative surface of S. aureus through electrostatic interaction, exhibiting effective antibacterial activity against both S. aureus and MRSA in vitro under light irradiation. Among the synthesized PPa-cP, PPa-cP5 with the degree of polymerization of 37 and modified with 1-methylimidazole side group exhibited the best antibacterial activity with a minimum inhibitory concentration (MIC) value of 2 μM without light irradiation and 0.25 μM with light irradiation. Moreover, PPa-cP5 showed good hemocompatibility. The above-mentioned results elucidate that the positively charged PPa-cP5 could significantly increase the efficiency of photodynamic therapy and effectively eradicate S. aureus biofilm due to its potent penetration ability into S. aureus biofilms. Overall, the present study establishes an efficient strategy for treatment of S. aureus and S. aureus biofilm infections. This article is protected by copyright. All rights reserved.

Low-Molecular-Weight Polylysines with Excellent Antibacterial Properties and Low Hemolysis

The steady development of bacterial resistance has become a global public health issue, and new antibacterial agents that are active against drug-resistant bacteria and less susceptible to bacterial resistance are urgently needed. Here, a series of low-molecular-weight cationic polylysines (C_x-PLL_n) with different hydrophobic end groups (C_x) and degrees of polymerization (PLL_n) was synthesized and used in antibacterial applications. All the obtained C_x-PLL_n have antibacterial activity. Among them, C₆-PLL₁₃ displays the best antibacterial effect for Gram-positive bacteria, that is, Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA), and highest selectivity against Gram-positive bacteria. A mechanistic study revealed that the C₆-PLL₁₃ destroys the integrity of the bacterial cell membrane and causes effective bacterial death. Owing to this membrane-disrupting property, C₆-PLL₁₃ showed rapid bacterial killing kinetics and was not likely to develop resistance after repeat treatment (up to 13 generations). Moreover, C₆-PLL₁₃ demonstrated a significant therapeutic effect on an MRSA infection mouse model, which further proved that this synthetic polymer could be used as an effective weapon against bacterial infections.

Fluorescent homopolypeptide toroids

Toroids are important ring-like nanostructures in living systems; intrinsically luminogenic toroids are promising in bioimaging but it is challenging to synthesize such nanoparticles. Herein, we report a fluorescent toroid that...

Polymer Vesicles for Antimicrobial Applications

Polymer vesicles, hollow nanostructures with hydrophilic cavity and hydrophobic membrane, have shown significant potentials in biomedical applications including drug delivery, gene therapy, cancer theranostics, and so forth, due to their unique cell membrane-like structure. Incorporation with antibacterial active components like antimicrobial peptides, etc., polymer vesicles exhibited enhanced antimicrobial activity, extended circulation time, and reduced cell toxicity. Furthermore, antibacterial, and anticancer can be achieved simultaneously, opening a new avenue of the antimicrobial applications of polymer vesicles. This review seeks to highlight the state-of-the-art of antimicrobial polymer vesicles, including the design strategies and potential applications in the field of antibacterial. The structural features of polymer vesicles, preparation methods, and the combination principles with antimicrobial active components, as well as the advantages of antimicrobial polymer vesicles, will be discussed. Then, the diverse applications of antimicrobial polymer vesicles such as wide spectrum antibacterial, anti-biofilm, wound healing, and tissue engineering associated with their structure features are presented. Finally, future perspectives of polymer vesicles in the field of antibacterial is also proposed.