Triclosan-based supramolecular hydrogels as nanoantibiotics for enhanced antibacterial activity

Antimicrobial activity of essential oil components against Escherichia coli depends on the food components present in a food matrix

Despite numerous studies evaluating the antimicrobial activity of essential oil components (EOCs) against different microorganisms, the effect of the composition of the matrix in which they are applied remains unexplored. Hence, the effect of different food components (i.e., proteins, lipids, carbohydrates, acids, ethanol) on vanillin antimicrobial activity was carried out by assessing the growth of E. coli at different incubation times (0, 1, 4, 8 and 24 h). Based on these outcomes, the food components that most adversely affected vanillin antimicrobial activity were subsequently tested with four other EOCs (i.e., carvacrol, eugenol, geraniol, thymol). The effective concentration of antimicrobials after coming into contact with food components was quantified. The results indicated that bovine serum albumin (BSA), sunflower oil and carbohydrates partially or completely inhibited the antimicrobial efficacy of the tested EOCs, and the inhibition rate depended on the specific EOC-food component combination. Geraniol was notably the most efficient with BSA present. Eugenol performed best with sunflower oil. Carvacrol, eugenol, geraniol and thymol were more effective than vanillin with D-lactose present. This study confirmed that loss of EOCs' effective concentration due to an interaction with food constituents is a significant cause of antimicrobial activity inhibition. These findings underscore the importance of considering matrix composition when selecting antimicrobials to combat a particular strain in real food applications.

Lethal puncturing of planktonic Gram-positive and Gram-negative bacteria by magnetically-rotated silica hexapods

Planktonic bacterial presence in many industrial and environmental applications and personal health-care products is generally countered using antimicrobials. However, antimicrobial chemicals present an environmental threat, while emerging resistance reduces their efficacy. Suspended bacteria have no defense against mechanical attack. Therefore, we synthesized silica hexapods on an α-Fe2O3 core that can be magnetically-rotated to inflict lethal cell-wall-damage to planktonic Gram-negative and Gram-positive bacteria. Hexapods possessed 600 nm long nano-spikes, composed of SiO2, as shown by FTIR and XPS. Fluorescence staining revealed cell wall damage caused by rotating hexapods. This damage was accompanied by DNA/protein release and bacterial death that increased with increasing rotational frequency up to 500 rpm. Lethal puncturing was more extensive on Gram-negative bacteria than on Gram-positive bacteria, which have a thicker peptidoglycan layer with a higher Young's modulus. Simulations confirmed that cell-wall-puncturing occurs at lower nano-spike penetration levels in the cell walls of Gram-negative bacteria. This approach offers a new way to kill bacteria in suspension, not based on antimicrobial chemicals.

Antimicrobial research of carbohydrate polymer- and protein-based hydrogels as reservoirs for the generation of reactive oxygen species: A review

Reactive oxygen species (ROS) play an important role in biological milieu. Recently, the rapid growth in our understanding of ROS and their promise in antibacterial applications has generated tremendous interest in the combination of ROS generators with bulk hydrogels. Hydrogels represent promising supporters for ROS generators and can locally confine the nanoscale distribution of ROS generators whilst also promoting cellular integration via biomaterial-cell interactions. This review highlights recent efforts and progress in developing hydrogels derived from biological macromolecules with embedded ROS generators with a focus on antimicrobial applications. Initially, an overview of passive and active antibacterial hydrogels is provided to show the significance of proper hydrogel selection and design. These are followed by an in-depth discussion of the various approaches for ROS generation in hydrogels. The structural engineering and fabrication of ROS-laden hydrogels are given with a focus on their biomedical applications in therapeutics and diagnosis. Additionally, we discuss how a compromise needs to be sought between ROS generation and removal for maximizing the efficacy of therapeutic treatment. Finally, the current challenges and potential routes toward commercialization in this rapidly evolving field are discussed, focusing on the potential translation of laboratory research outcomes to real-world clinical outcomes.

Stimuli-responsive peptide hydrogels for biomedical applications

Stimuli-responsive hydrogels can respond to external stimuli with a change in the network structure and thus have potential application in drug release, intelligent sensing, and scaffold construction. Peptides possess robust supramolecular self-assembly ability, enabling spontaneous formation of nanostructures through supramolecular interactions and subsequently hydrogels. Therefore, peptide-based stimuli-responsive hydrogels have been widely explored as smart soft materials for biomedical applications in the last decade. Herein, we present a review article on design strategies and research progress of peptide hydrogels as stimuli-responsive materials in the field of biomedicine. The latest design and development of peptide hydrogels with responsive behaviors to stimuli are first presented. The following part provides a systematic overview of the functions and applications of stimuli-responsive peptide hydrogels in tissue engineering, drug delivery, wound healing, antimicrobial treatment, 3D cell culture, biosensors, etc. Finally, the remaining challenges and future prospects of stimuli-responsive peptide hydrogels are proposed. It is believed that this review will contribute to the rational design and development of stimuli-responsive peptide hydrogels toward biomedical applications.

Progress of stimulus responsive nanosystems for targeting treatment of bacterial infectious diseases

In recent decades, due to insufficient concentration at the lesion site, low bioavailability and increasingly serious resistance, antibiotics have become less and less dominant in the treatment of bacterial infectious diseases. It promotes the development of efficient drug delivery systems, and is expected to achieve high absorption, targeted drug release and satisfactory therapy effects. A variety of endogenous stimulation-responsive nanosystems have been constructed by using special infection microenvironments (pH, enzymes, temperature, etc.). In this review, we firstly provide an extensive review of the current research progress in antibiotic treatment dilemmas and drug delivery systems. Then, the mechanism of microenvironment characteristics of bacterial infected lesions was elucidated to provide a strong theoretical basis for bacteria-targeting nanosystems design. In particular, the discussion focuses on the design principles of single-stimulus and dual-stimulus responsive nanosystems, as well as the use of endogenous stimulus-responsive nanosystems to deliver antimicrobial agents to target locations for combating bacterial infectious diseases. Finally, the challenges and prospects of endogenous stimulus-responsive nanosystems were summarized.

Antimicrobial Hydrogels: Potential Materials for Medical Application

Microbial infections based on drug-resistant pathogenic organisms following surgery or trauma and uncontrolled bleeding are the main causes of increased mortality from trauma worldwide. The prevalence of drug-resistant pathogens has led to a significant increase in medical costs and poses a great threat to the normal life of people. This is an important issue in the field of biomedicine, and the emergence of new antimicrobial materials hydrogels holds great promise for solving this problem. Hydrogel is an important material with good biocompatibility, water absorption, oxygen permeability, adhesion, degradation, self-healing, corrosion resistance, and controlled release of drugs as well as structural diversity. Bacteria-disturbing hydrogels have important applications in the direction of surgical treatment, wound dressing, medical device coating, and tissue engineering. This paper reviews the classification of antimicrobial hydrogels, the current status of research, and the potential of antimicrobial hydrogels for one application in biomedicine, and analyzes the current research of hydrogels in biomedical applications from five aspects: metal-loaded hydrogels, drug-loaded hydrogels, carbon-material-loaded hydrogels, hydrogels with fixed antimicrobial activity and biological antimicrobial hydrogels, and provides an outlook on the high antimicrobial activity, biodegradability, biocompatibility, injectability, clinical applicability and future development prospects of hydrogels in this field.

Low-Cytotoxicity, Broad-Spectrum Corn Starch-Based Antibacterial Particles that Inhibit Multidrug-Resistant Bacteria

Antimicrobial resistance is a serious problem in biomedical applications that seriously increases the risk of medical failure. Therefore, developing highly efficient antibacterial agents that inhibit the growth of multidrug-resistant bacteria is a long-standing research goal. In this report, a low-cytotoxicity and highly efficient alternative to antibiotics was designed and prepared using edible corn starch as the scaffold and 2-hydroxypropyl-trimethylammonium chloride chitosan (HTCC) as the antimicrobial agent. The HTCC/starch particles were found to have a positively charged surface over a wide pH range and to possess broad-spectrum and highly efficient antimicrobial properties. These particles inhibited the growth of standard Gram-positive and Gram-negative bacteria from the China Pharmacopoeia and a clinical multidrug-resistant bacterial strain. Moreover, after treating the HTCC/starch particles with simulated gastric fluid (SGF, pH 1.2) for 4 h, the growth of clinical multidrug-resistant Escherichia coli (NT 2036) was inhibited effectively, indicating that these particles tolerate a gastric acid environment. Although the mass of SGF-treated HTCC/starch particles required to achieve similar antibacterial activity was ∼20-fold that of chloramphenicol or ampicillin, antibiotic-containing products require considerable amounts of pharmaceutical excipients to prepare. Therefore, the HTCC/starch particles described herein are potentially cost-effective alternatives to antibiotics that resolve the antimicrobial resistance issue, especially for inhibiting the growth of pathogenic intestinal bacteria.

Supramolecular gels - a panorama of low-molecular-weight gelators from ancient origins to next-generation technologies

Supramolecular gels, self-assembled from low-molecular-weight gelators (LMWGs), have a long history and a bright future. This review provides an overview of these materials, from their use in lubrication and personal care in the ancient world, through to next-generation technologies. In academic terms, colloid scientists in the 19th and early 20th centuries first understood such gels as being physically assembled as a result of weak interactions, combining a solid-like network having a degree of crystalline order with a highly mobile liquid-like phase. During the 20th century, industrial scientists began using these materials in new applications in the polymer, oil and food industries. The advent of supramolecular chemistry in the late 20th century, with its focus on non-covalent interactions and controlled self-assembly, saw the horizons for these materials shifted significantly beyond their historic rheological applications, expanding their potential. The ability to tune the LMWG chemical structure, manipulate hierarchical assembly, develop multi-component systems, and introduce new types of responsive and interactive behaviour, has been transformative. Furthermore, the dynamics of these materials are increasingly understood, creating metastable gels and transiently-fueled systems. New approaches to shaping and patterning gels are providing a unique opportunity for more sophisticated uses. These supramolecular advances are increasingly underpinning and informing next-generation applications - from drug delivery and regenerative medicine to environmental remediation and sustainable energy. In summary, this article presents a panorama over the field of supramolecular gels, emphasising how both academic and industrial scientists are building on the past, and engaging new fundamental insights and innovative concepts to open up exciting horizons for their future use.

Versatile Biodegradable Poly(acrylic acid)-Based Hydrogels Infiltrated in Porous Titanium Implants to Improve the Biofunctional Performance

This research work proposes a synergistic approach to improve implants' performance through the use of porous Ti substrates to reduce the mismatch between Young's modulus of Ti (around 110 GPa) and the cortical bone (20-25 GPa), and the application of a biodegradable, acrylic acid-based polymeric coating to reduce bacterial adhesion and proliferation, and to enhance osseointegration. First, porous commercially pure Ti substrates with different porosities and pore size distributions were fabricated by using space-holder techniques to obtain substrates with improved tribomechanical behavior. On the other hand, a new diacrylate cross-linker containing a reduction-sensitive disulfide bond was synthesized to prepare biodegradable poly(acrylic acid)-based hydrogels with 1, 2, and 4% cross-linker. Finally, after the required characterization, both strategies were implemented, and the combination of 4% cross-linked poly(acrylic acid)-based hydrogel infiltrated in 30 vol % porosity, 100-200 μm average pore size, was revealed as an outstanding choice for enhancing implant performance.

Mxene-Based Supramolecular Composite Hydrogels for Antioxidant and Photothermal Antibacterial Activities

Bacterial infections and oxidative damage caused by various reactive oxygen species (ROS) pose a significant threat to human health. It is highly desirable to find an ideal biomaterial system with broad spectrum antibacterial and antioxidant capabilities. A new supramolecular antibacterial and antioxidant composite hydrogel made of chiral L-phenylalanine-derivative (LPFEG) as matrix and Mxene (Ti3 C2 Tx ) as filler material is presented. The noncovalent interactions (H-bonding and π-π interactions) in between LPFEG and Mxene and the inversion of LPFEG chirality are verified by Fourier transform infrared and circular dichroism spectroscopy. The composite hydrogels show improved mechanical properties revealed by rheological analysis. The composite hydrogel system exhibits photothermal conversion efficiency (40.79%), which enables effective photothermal broad-spectrum antibacterial activities against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. Furthermore, the Mxene also enables the composite hydrogel to exhibit excellent antioxidant activity by efficiently scavenging free radicals like DPPH•, ABTS•+, and •OH. These results indicate that the Mxene-based chiral supramolecular composite hydrogel, with improved rheological, antibacterial, and antioxidant properties has a great potential for biomedical applications.

Photocuring and Gelatin-Based Antibacterial Hydrogel for Skin Care

The development of moisturizing, antibacterial, and biocompatible multifunctional hydrogels is essential to protect skin and promote skin defects recovery. Gelatin has admired potential to be applied for skin care as a hydrogel in virtue of its hydrophilic biocompatible and biodegradable properties. In this study, triclosan-grafted gelatin and photo-cross-linkable methacrylated gelatin were synthesized and then combined to construct the semi-interpenetrating network and antibacterial hydrogels with the aid of a visible blue light. The antimicrobial test demonstrated that the resulting hydrogel obtained excellent inactivation capacity against E. coli, S. aureus, T. rubrum, and C. albicans with sterilizing rates of 99.998%, 99.998%, 99.19%, and 99.64%, respectively. In addition, the cytotoxicity, hemolysis, skin irritation, and rat skin wound healing experiments proved the good biocompatibility of the hydrogel. Therefore, this investigation sheds light on the development of multifunctional hydrogels in skin care.

Environmental endocrine disruptors and pregnane X receptor action: A review

The pregnane X receptor (PXR) is a kind of orphan nuclear receptor activated by a series of ligands. Environmental endocrine disruptors (EEDs) are a wide class of molecules present in the environment that are suspected to have adverse effects on the endocrine system by interfering with the synthesis, transport, degradation, or action of endogenous hormones. Since EEDs may modulate human/rodent PXR, this review aims to summarize EEDs as PXR modulators, including agonists and antagonists. The modular structure of PXR is also described, interestingly, the pharmacology of PXR have been confirmed to vary among different species. Furthermore, PXR play a key role in the regulation of endocrine function. Endocrine disruption of EEDs via PXR and its related pathways are systematically summarized. In brief, this review may provide a way to understand the roles of EEDs in interaction with the nuclear receptors (such as PXR) and the related pathways.

Injectable In Situ Photocrosslinked Hydrogel Dressing for Infected Wound Healing

A traditional injectable photocrosslinked hydrogel had disadvantages of the residual photoinitiator and toxic crosslinker, slow in situ curing, and a complex preparation process. At the same time, hydrogels cannot act as artificial skin to restore skin sensory function during the wound healing cycle. In this work, an injectable photocrosslinked hydrogel was prepared which can be quickly in situ cured without photoinitiator. Oxidized sodium alginate was used as a natural macromolecular crosslinking agent to form an injectable hydrogel framework with the photosensitive polymer polyvinyl alcohol bearing styrylpyridinium group (PVA-SBQ). In addition, the hydrogel was endowed with photothermal therapy property after the introduction of biomass-like polydopamine particles. When used as a wound dressing, the hydrogel exhibited an excellent antibacterial property, with an antibacterial rate of 99.56% Escherichia coli and 97.96% Staphylococcus aureus. As a result, the hydrogel could significantly accelerate the repair of infected wounds, with a wound healing rate of 96.45% after 14 days. Moreover, the hydrogel exhibited a sensitive and stable sensing property, making it promising to reconstitute the sensory function of damaged skin during treatment. This work provides an idea for the development of injectable photocrosslinked hydrogel dressing.

Nanotechnology: a contemporary therapeutic approach in combating infections from multidrug-resistant bacteria

In the 20th century, the discovery of antibiotics played an essential role in the fight against infectious diseases, including meningitis, typhoid fever, pneumonia and Mycobacterium tuberculosis. The development of multidrug resistance in microflora due to improper antibiotic use created significant public health issues. Antibiotic resistance has increased at an alarming rate in the past few decades. Multidrug-resistant bacteria (superbugs) such as methicillin-resistant Staphylococcus aureus (MRSA) as well as drug-resistant tuberculosis pose serious health implications. Despite the continuous increase in resistant microbes, the discovery of novel antibiotics is constrained by the cost and complexities of discovery of drugs. The nanotechnology has given new hope in combating this problem. In the present review, recent developments in therapeutics utilizing nanotechnology for novel antimicrobial drug development are discussed. The nanoparticles of silver, gold and zinc oxide have proved to be efficient antimicrobial agents against multidrug-resistant Klebsiella, Pseudomonas, Escherichia Coli and MRSA. Using nanostructures as carriers for antimicrobial agents provides better bioavailability, less chances of sub-therapeutic drug accumulation and less drug-related toxicity. Nanophotothermal therapy using fullerene and antibody functionalized nanostructures are other strategies that can prove to be helpful.

Enzyme-triggered smart antimicrobial drug release systems against bacterial infections

The rapid emergence and spread of drug-resistant bacteria, as one of the most pressing public health threats, are declining our arsenal of available antimicrobial drugs. Advanced antimicrobial drug delivery systems that can achieve precise and controlled release of antimicrobial agents in the microenvironment of bacterial infections will retard the development of antimicrobial resistance. A variety of extracellular enzymes are secreted by bacteria to destroy physical integrity of tissue during their invasion of host body, which can be utilized as stimuli to trigger "on-demand" release of antimicrobials. In the past decade, such bacterial enzyme responsive drug release systems have been intensively studied but few review has been released. Herein, we systematically summarize the recent progress of smart antimicrobial drug delivery systems triggered by bacteria secreted enzymes such as lipase, hyaluronidase, protease and antibiotic degrading enzymes. The perspectives and existing key issues of this field will also be discussed to fuel the innovative research and translational application in the future.

Self-assembly hydrogels of therapeutic agents for local drug delivery

Advanced drug delivery systems are of vital importance to enhance therapeutic efficacy. Among various recently developed formulations, self-assembling hydrogels composed of therapeutic agents have shown promising potential for local drug delivery owing to their excellent biocompatibility, high drug-loading efficiency, low systemic toxicity, and sustained drug release behavior. In particular, therapeutic agents self-assembling hydrogels with well-defined nanostructures are beneficial for direct delivery to the target site via injection, not only improving drug availability, but also extending their retention time and promoting cellular uptake. In brief, the self-assembly approach offers better opportunities to improve the precision of pharmaceutical treatment and achieve superior treatment efficacies. In this review, we intend to cover the recent developments in therapeutic agent self-assembling hydrogels. First, the molecular structures, self-assembly mechanisms, and application of self-assembling hydrogels are systematically outlined. Then, we summarize the various self-assembly strategies, including the single therapeutic agent, metal-coordination, enzyme-instruction, and co-assembly of multiple therapeutic agents. Finally, the potential challenges and future perspectives are discussed. We hope that this review will provide useful insights into the design and preparation of therapeutic agent self-assembling hydrogels.

Lactobacillus cell envelope-coated nanoparticles for antibiotic delivery against cariogenic biofilm and dental caries

Background

Due to their prevalence, dental caries ranks first among all diseases endangering human health. Therefore, the prevention of caries is of great significance, as caries have become a serious public health problem worldwide. Currently, using nanoscale drug delivery systems to prevent caries has received increased attention. However, the preventive efficacy of these systems is substantially limited due to the unique physiological structure of cariogenic biofilms. Thus, novel strategies aimed at combating cariogenic biofilms to improve preventive efficiency against caries are meaningful and very necessary. Herein, inspired by cell membrane coating technology and Lactobacillus strains, we coated triclosan (TCS)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (TCS@PLGA-NPs) with an envelope of Lactobacillus (LA/TCS@PLGA-NPs) and investigated their potential as a nanoparticle delivery system against cariogenic biofilms and dental caries.

Results

LA/TCS@PLGA-NPs were successfully prepared with favorable properties, including a coated envelope, controllable size, negative charge, sustained drug-release kinetics and so on. The LA/TCS@PLGA-NPs inherited native properties from the source cell surface, thus the LA/TCS@PLGA-NPs adhered to S. mutans, integrated into the S. mutans biofilm, and interfered with the biofilm formation of S. mutans. The nanoparticles significantly inhibited the activity, biomass and virulence gene expression of S. mutans biofilms in vitro. Additionally, LA/TCS@PLGA-NPs exhibited a long-lasting inhibitory effect on the progression of caries in vivo. The safety performance of the nanoparticles is also favorable.

Conclusions

Our findings reveal that the antibiofilm effect of LA/TCS@PLGA-NPs relies not only on the inheritance of native properties from the Lactobacillus cell surface but also on the inhibitory effect on the activity, biomass and virulence of S. mutans biofilms. Thus, these nanoparticles could be considered feasible candidates for a new class of effective drug delivery systems for the prevention of caries. Furthermore, this work provides new insights into cell membrane coating technology and presents a novel strategy to combat bacterial biofilms and associated infections.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01563-x.

Inducible endothelial leakiness in nanotherapeutic applications

All intravenous delivered nanomedicine needs to escape from the blood vessel to exert their therapeutic efficacy at their designated site of action. Failure to do so increases the possibility of detrimental side effects and negates their therapeutic intent. Many powerful anticancer nanomedicine strategies rely solely on the tumor derived enhanced permeability and retention (EPR) effect for the only mode of escaping from the tumor vasculature. However, not all tumors have the EPR effect nor can the EPR effect be induced or controlled for its location and timeliness. In recent years, there have been exciting developments along the lines of inducing endothelial leakiness at the tumor to decrease the dependence of EPR. Physical disruption of the endothelial-endothelial cell junctions with coordinated biological intrinsic pathways have been proposed that includes various modalities like ultrasound, radiotherapy, heat and even nanoparticles, appear to show good progress towards the goal of inducing endothelial leakiness. This review explains the intricate and complex biological background behind the endothelial cells with linkages on how updated reported nanomedicine strategies managed to induce endothelial leakiness. This review will also end off with fresh insights on where the future of inducible endothelial leakiness holds.

Triclosan: A Small Molecule with Controversial Roles

Triclosan (TCS), a broad-spectrum antimicrobial agent, has been widely used in personal care products, medical products, plastic cutting boards, and food storage containers. Colgate Total® toothpaste, containing 10 mM TCS, is effective in controlling biofilm formation and maintaining gingival health. Given its broad usage, TCS is present ubiquitously in the environment. Given its strong lipophilicity and accumulation ability in organisms, it is potentially harmful to biohealth. Several reports suggest the toxicity of this compound, which is inserted in the class of endocrine disrupting chemicals (EDCs). In September 2016, TCS was banned by the U.S. Food and Drug Administration (FDA) and the European Union in soap products. Despite these problems, its application in personal care products within certain limits is still allowed. Today, it is still unclear whether TCS is truly toxic to mammals and the adverse effects of continuous, long-term, and low concentration exposure remain unknown. Indeed, some recent reports suggest the use of TCS as a repositioned drug for cancer treatment and cutaneous leishmaniasis. In this scenario it is necessary to investigate the advantages and disadvantages of TCS, to understand whether its use is advisable or not. This review intends to highlight the pros and cons that are associated with the use of TCS in humans.

Structure of Self-assembled Peptide Determines the Activity of Aggregation-Induced Emission Luminogen-Peptide Conjugate for Detecting Alkaline Phosphatase

The unique property of turning on their fluorescence after aggregation or assembly makes aggregation-induced emission luminogens (AIEgens) ideal luminescent molecules for the construction of self-assembled peptide-based nanoprobes. However, the characteristic highly twisted or propeller-shaped molecular conformation of AIEgens tends to prevent the assembly of AIEgen-peptides. Here, we show that (i) the distance between tetraphenylethene (TPE) and assembled peptides should not be too far (less than five glycines), otherwise the self-assembly of peptides cannot limit the intramolecular rotation of conjugated TPE and the luminous efficiency of TPE-peptide to alkaline phosphatase (ALP) will decrease; (ii) properly increasing the number of amino acids with self-assembly ability (three phenylalanines) can improve their ALP-responsive self-assembly and luminescence ability; (iii) the strategy of co-assembly with a non-AIEgen-capped self-assembled peptide is a simple and effective way to realize the efficient assembly and luminescence of AIEgen-peptides; and (iv) the hydrophilic and hydrophobic balance of the probe should always be considered in the construction of an efficient AIEgen-peptide probe. In addition, AIEgen-peptide probes show good selectivity and sensitivity for ALP detection both in vitro and in live bacteria. These insights illustrated here are crucial for guiding the design of AIEgen-conjugated supramolecular materials, especially for the construction of AIEgen-peptides, for enzymes detection, biomarker imaging, diseases therapy, and other biomedical fields.

An edible kanamycin sulfate cross-linked cellulose active against multiple pathogenic bacteria

In this work, an edible cellulose-based antibacterial material was prepared by cross-linking α-cellulose and kanamycin sulfate via glutaraldehyde to form kanamycin sulfate-glutaraldehyde-cellulose. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction results indicated that the kanamycin sulfate molecule was cross-linked with the molecular chain of cellulose. The optimal mass ratio of kanamycin sulfate to α-cellulose was 1:100 and the degree of substitution reached 1.11%. The optimal kanamycin sulfate-glutaraldehyde-cellulose material showed an excellent inhabitation against both Gram-positive and Gram-negative bacteria. Meantime, the optimal kanamycin sulfate-glutaraldehyde-cellulose had a marked resistance to gastric acid and had low cell cytotoxicity. To promote the application of the kanamycin sulfate-glutaraldehyde-cellulose material, the porous microspheres were prepared via the sol-gel method. The particle size of the homogeneous porous microspheres is mainly distributed between 1.5 and 2.0 μm. Therefore, the kanamycin sulfate-glutaraldehyde-cellulose described herein is a potential edible, eco-friendly, potent, stable, inexpensive, and antibacterial carrier material for delivering drugs, proteins, or vaccines.

Paclitaxel-based supramolecular hydrogel loaded with mifepristone for the inhibition of breast cancer metastasis

Breast cancer is the leading cause of cancer death among women and almost all of the breast cancer-caused mortality is related to metastasis. It has been reported that glucocorticoid facilitates the metastasis of breast cancer in mice, and mifepristone can antagonize the effect of glucocorticoid. Paclitaxel is one of the important drugs in the treatment of breast cancer. Mifepristone combined with paclitaxel could be an effective strategy for inhibiting breast cancer metastasis. However, their inherent defects, in terms of short blood circulation half-life and lack of tumor targeting, not only limit their effectiveness but also cause adverse reactions. Therefore, our aim is to explore a novel protocol against breast cancer metastasis, further optimize its therapeutic efficacy by a nanodelivery system, and explore its mechanism. Herein, a paclitaxel-conjugated and mifepristone-loaded hydrogel (PM-nano) was prepared by self-assembly. Its characterizations were studied. The antimetastatic effect was evaluated in vitro and in vivo and its mechanism was also explored by western blot assay. The resultant PM-nano was developed with favorable water solubility and good biocompatibility. Moreover, PM-nano displayed increased cell uptake properties and stimulated drug release in the tumor micro-acidic environment. The PM-nano was more effective in inhibiting the proliferation and metastasis of breast cancer than other groups in vitro and in vivo. The PM-nano might inhibit metastasis through glucocorticoid receptor/receptor tyrosine kinase-like orphan receptor 1 and MMPs. Taken together, PM-nano showed superior antimetastatic effects against breast cancer and excellent biocompatibility in vitro and in vivo, providing a new option for limiting metastasis.

Water-soluble PANI:PSS designed for spontaneous non-disruptive membrane penetration and direct intracellular photothermal damage on bacteria

The major challenge in the field of antibacterial agents is to overcome the low-permeability of bacteria cell membranes that protects the cells against diverse drugs. In this work, water-soluble polyaniline (PANI)-poly (p-styrenesulfonic acid) (PSS) (PANI:PSS) is found to spontaneously penetrate bacteria cellular membranes in a non-disruptive way, leaving no evidence of membrane poration/disturbance or cell death, thus avoiding side effects caused by cationic ammonia groups in traditional ammonia-containing antibacterial agents. For aqueous synthesis, which is important for biocompatibility, the polymer is synthesized via an enzyme-mimetic route relying on the catalysis of a nanozyme. Owing to its fluorescent properties, the localization of as-prepared PANI:PSS is determined by the confocal microscope, and the results confirm its rapid entry into bacteria. Under 808 nm near-infrared (NIR) irradiation, the internalized PANI:PSS generates local hyperthermia and destroys bacteria highly efficiently from inside the cells due to its excellent photothermal effects. Staphylococcus aureus (S. aureus), M ethicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) could be effectively eliminated as well as the corresponding bacterial biofilms. Results of in vivo antibacterial experiments demonstrate excellent antibacterial activities of the water-soluble PANI:PSS without side effects. Therefore, the prepared water-soluble polymer in this study has great potential in the treatment of various bacterial infections.

A spatiotemporal release platform based on pH/ROS stimuli-responsive hydrogel in wound repairing

Fabricating injectable hydrogel with multifunctions that matchs the highly ordered healing process of skin regeneration has greatly desired in treatment of chronic diabetic wounds. Herein, a pH/reactive oxygen species (ROS) dual responsive injectable glycopeptide hydrogel based on phenylboronic acid-grafted oxidized dextran and caffeic acid-grafted ε-polylysine was constructed, which exhibited inherent antibacterial and antioxidant capacities. The mangiferin (MF) with the ability to promote angiogenesis was encapsulated into pH-responsive micelles (MIC). Subsequently, diclofenac sodium (DS) with anti-inflammatory activities and MIC@MF were embedded into the hydrogel. The hydrogel possessed good biodegradability, stable rheological property and self-healing ability, and could realize the spatiotemporal delivery of DS and MF. The in vitro and in vivo data showed that the hydrogel was biocompatible with effective anti-infection, anti-oxidation and anti-inflammation at early stages, then further promoted angiogenesis and accelerated wound repairing. Collectively, this novel glycopeptide hydrogel provides a facile and effective strategy for chronic diabetic wound repairing.

Evaluations of Electrostatic Filtration Efficiency and Antibacterial Efficacy of Antibacterial Electret Polypropylene Filters: Effects of Using Low Molecular Antibacterial Agent as Additive

In recent years, air filtration has been gaining much attention, and now people are much more concerned about antibacterial filters due to the spreading of COVID-19. The electret polypropylene (PP) nonwoven fabrics possess excellent filtration efficiency but a limited antibacterial effect against S. aureus and E. coli, and therefore triclosan is used in this study. Serving as an antibacterial agent, triclosan with a low molecular weight is an effective additive for the test results, indicating that the presence of triclosan strengthens the antibacterial effects of the filters. In addition, triclosan also strengthens the PP’s crystallinity, which in turn betters the filtration efficiency of the filters concurrently. Demonstrating powerful filtration and antibacterial performances, the antibacterial electret PP filters are highly qualified for filter applications.

Advancements in release-active antimicrobial biomaterials: A journey from release to relief

Escalating medical expenses due to infectious diseases are causing huge socioeconomic pressure on mankind globally. The emergence of antibiotic resistance has further aggravated this problem. Drug-resistant pathogens are also capable of forming thick biofilms on biotic and abiotic surfaces to thrive in a harsh environment. To address these clinical problems, various strategies including antibacterial agent delivering matrices and bactericidal coatings strategies have been developed. In this review, we have discussed various types of polymeric vehicles such as hydrogels, sponges/cryogels, microgels, nanogels, and meshes, which are commonly used to deliver antibiotics, metal nanoparticles, and biocides. Compositions of these polymeric matrices have been elaborately depicted by elucidating their chemical interactions and potential activity have been discussed. On the other hand, various implant/device-surface coating strategies which exploit the release-active mechanism of bacterial killing are discussed in elaboration. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease.

γ-Ray-Triggered Drug Release of Reactive Oxygen Species-Sensitive Nanomedicine for Enhanced Concurrent Chemoradiation Therapy

Radiotherapy (RT) combined with chemotherapy remains a dominant therapeutic manner in clinical tumor treatment, which is irreplaceable in a short term. To seek an intrinsic connection of combined chemoradiation therapy and maximize the antitumor efficacy, we developed a reactive oxygen species (ROS)-sensitive nanomicelle drug delivery system based on a self-assembled amphiphilic polymer, hyaluronic acid-graft-poly-(propylene sulfide) (HA-PPS). A chemical radiosensitizer, doxorubicin (DOX), was encapsulated into the core of HA-PPS nanomicelles, constituting the DOX-loaded nanomicelles (HA-PPS@DOX NMs) with a spherical structure of around 205.10 ± 11.33 nm diameter with a narrow polydispersity index (PDI) of 0.135 ± 0.01. When combined with RT, the ROS-sensitive HA-PPS@DOX NMs disintegrated and released great drug cargos, which further enhanced cytotoxicity. Meanwhile, as a radiosensitizer, the released DOX sensitized cancer cells to radiotherapy, which has been confirmed by an enhanced sensitizer enhancement ratio (SER) value of 1.78 contributing to the increased cytotoxicity of concurrent chemoradiation tumor therapy, as evidenced by the improvement of half maximal inhibitory concentration (IC₅₀ value) of DOX from 2.316 to 0.8235 μg/mL. Moreover, in vivo studies revealed that HA-PPS@DOX NMs exhibited prolonged circulation time and improved tumor accumulation. Particularly, the released DOX triggered by radiation strengthened radiotherapy sensitization in return. Consequently, these superiorities of HA-PPS@DOX NMs shown by the concurrent chemoradiation tumor therapy resulted in an ideal tumor inhibition rate of 70.4%, thus providing a promising ROS-sensitive nanomedicine for cancer treatment.

Biological functions of supramolecular assemblies of small molecules in cellular environment

Like biomacromolecules, certain small molecules (e.g., aggregators) are able to self-assemble in aqueous phase to form nanoscale aggregates. Though it is well-established that the aggregates may interact with enzymes in vitro, the study of the biological activities of the assemblies of small molecules in cellular environment is only at its beginning. This review summarizes the recent progresses in exploring the biological functions of supramolecular assemblies of small molecules (SASMs). We first discuss the use of SASMs to inhibit pathogenic cells, such as cancer cells and bacteria. The use of SASMs to target different parts of cancer cells, such as pericellular space, cytosol, and subcellular organelles, and to combine with other bioactive entities (e.g., proteins and clinically used drugs), is particularly promising for addressing the challenge of acquired multidrug resistance in cancer therapy. Then, we describe the use of SASMs to sustain physiological functions of normal cells, that is, promoting cells proliferation and differentiation for tissue regeneration. After that, we show the use of SASMs as a basic tool to research cell behaviors, for instance, identifying the specific cells, improving enzyme probes, revealing membrane dynamics, enhancing molecular imaging, and mimicking context-dependent signaling. Finally, we give the outlook of the research of SASMs. We expect that this review, by highlighting the biological functions of SASMs, provides a starting point to explore the chemical biology of SASMs.

Carbon dots derived from kanamycin sulfate with antibacterial activity and selectivity for Cr6+ detection

Among antibacterial nanomaterials, carbon dots (CDs) have attracted much attention because of their unique physical and chemical properties and good biosafety. In this study, kanamycin sulfate (Kan), a broad-spectrum antibiotic, was used to synthesize novel carbon dots (CDs-Kan) by a one-step hydrothermal method. CDs-Kan showed good inhibitory effects on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Further, scanning electron microscopy revealed that treatment with CDs-Kan and Kan resulted in the same phenomena. In particular, the morphologies of S. aureus cells treated with CDs-Kan and Kan became smaller and irregular, whereas the surfaces of E. coli cells protruded and formed vesicles. These results indicated that CDs-Kan was shown to retain the good antibacterial activity of Kan as well as its main bactericidal functional groups, namely, the amino sugar and amino cyclic alcohol, We refer to this phenomenon as the "preservation property". We also found that CDs-Kan has good biocompatibility and nontoxic properties. Moreover, CDs-Kan was successfully applied to the biological imaging of fungi and plant cells. In addition, CDs-Kan could be used as a fluorescent probe for the quick, sensitive, and selective detection of Cr⁶⁺. Therefore, CDs-Kan not only retained the good bacteriostatic properties of Kan but also expanded its application in bioimaging and biosensors.

Effective Antibacterial Activity of Degradable Copper-Doped Phosphate-Based Glass Nanozymes

Copper-containing antimicrobials are highly valuable in the field of medical disinfectants owing to their well-known high antimicrobial efficacy. Artificially synthesized nanozymes which can increase the level of reactive oxygen species (ROS) in the bacterial system have become research hotspots. Herein, we describe the design and fabrication of degradable Cu-doped phosphate-based glass (Cu-PBG) nanozyme, which can achieve excellent antibacterial effects against Gram-positive and Gram-negative bacteria. The antibacterial mechanism is based on the generation of ROS storm and the release of copper. It behaves like a peroxidase in wounds which are acidic and exerts lethal oxidative stress on bacteria via catalyzing the decomposition of H₂O₂ into hydroxyl radicals (^•OH). Quite different from any other reported nanozymes, the Cu-PBG is intrinsically degradable due to its phosphate glass nature. It gradually degrades and releases copper ions in a physiological environment, which further enhances the inhibition efficiency. Satisfactory antibacterial effects are verified both in vitro and in vivo. Being biodegradable, the prepared Cu-PBG exhibits excellent in vivo biocompatibility and does not cause any adverse effects caused by its long-time residence time in living organisms. Collectively, these results indicate that the Cu-PBG nanozyme could be used as an efficient copper-containing antimicrobial with great potential for clinical translation.

Biofabricated Fatty Acids-Capped Silver Nanoparticles as Potential Antibacterial, Antifungal, Antibiofilm and Anticancer Agents

The current study demonstrates the synthesis of fatty acids (FAs) capped silver nanoparticles (AgNPs) using aqueous poly-herbal drug Liv52 extract (PLE) as a reducing, dispersing and stabilizing agent. The NPs were characterized by various techniques and used to investigate their potent antibacterial, antibiofilm, antifungal and anticancer activities. GC-MS analysis of PLE shows a total of 37 peaks for a variety of bio-actives compounds. Amongst them, n-hexadecanoic acid (21.95%), linoleic acid (20.45%), oleic acid (18.01%) and stearic acid (13.99%) were found predominately and most likely acted as reducing, stabilizing and encapsulation FAs in LIV-AgNPs formation. FTIR analysis of LIV-AgNPs shows some other functional bio-actives like proteins, sugars and alkenes in the soft PLE corona. The zone of inhibition was 10.0 ± 2.2-18.5 ± 1.0 mm, 10.5 ± 2.5-22.5 ± 1.5 mm and 13.7 ± 1.0-16.5 ± 1.2 against P. aeruginosa, S. aureus and C. albicans, respectively. LIV-AgNPs inhibit biofilm formation in a dose-dependent manner i.e., 54.4% ± 3.1%-10.12% ± 2.3% (S. aureus), 72.7% ± 2.2%-23.3% ± 5.2% (P. aeruginosa) and 85.4% ± 3.3%-25.6% ± 2.2% (C. albicans), and SEM analysis of treated planktonic cells and their biofilm biomass validated the fitness of LIV-AgNPs in future nanoantibiotics. In addition, as prepared FAs rich PLE capped AgNPs have also exhibited significant (p < 0.05 *) antiproliferative activity against cultured HCT-116 cells. Overall, this is a very first demonstration on employment of FAs rich PLE for the synthesis of highly dispersible, stable and uniform sized AgNPs and their antibacterial, antifungal, antibiofilm and anticancer efficacy.

Self-crosslinked chitosan/dialdehyde xanthan gum blended hypromellose hydrogel for the controlled delivery of ampicillin, minocycline and rifampicin

The design of improved biopolymeric based hydrogel materials with high load-capacity to serve as biocompatible drug carriers is a challenging task with vital implications in health sciences. In this work, chitosan crosslinked dialdehyde xanthan gum interpenetrated hydroxypropyl methylcellulose gels were developed for the controlled delivery of different antibiotic drugs including ampicillin, minocycline and rifampicin. The prepared hydrogel scaffolds were characterized by rheology method, FTIR, SEM, TGA and compression analysis. In addition, gelation kinetics, swelling, in vitro degradation and drug release rate were studied under simulated gastrointestinal fluid conditions of pH 2.0 and 7.4 at 37 °C. Results demonstrated the gel composition and structure affected drug release kinetics. The release study showed more than 50% cumulative release within 24 h for all investigated antibiotic drugs. In vitro cell cytocompatibility using mouse embryonic fibroblast cell lines depicted ≥80% cell viability, indicating the gels are non-toxic. Finally, the antibacterial activity of loaded gels was evaluated against Gram-negative and positive bacteria (Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia), which correlated well with swelling and drug release results. Overall, the present study demonstrated that the produced hydrogel scaffolds serves as promising material for controlled antibiotic delivery towards microbial growth inhibition.

Encapsulation of Lactobacillus rhamnosus in Hyaluronic Acid-Based Hydrogel for Pathogen-Targeted Delivery to Ameliorate Enteritis

Probiotics were found to be effective in ameliorating the microbial dysbiosis and inflammation caused by intestinal pathogens. However, biological challenges encountered during oral delivery have greatly limited their potential health benefits. Here, a model probiotic (Lactobacillus rhamnosus) was encapsulated in an intestinal-targeted hydrogel to alleviate bacterial enteritis in a novel mode. The hydrogel was prepared simply by the self-cross-linking of thiolated hyaluronic acid. Upon exposure to H₂S which were excreted by surrounding intestinal pathogens, the hydrogel can locally degrade and rapidly release cargos to compete with source pathogens in turn for binding to the host. The mechanical properties of hydrogel were studied by rheological analysis, and the ideal stability was achieved at a polymer concentration of 4% (w/v). The morphology of the optimal encapsulation system was further measured by a scanning electron microscope, exhibiting uniform payload of probiotics. Endurance experiments indicated that the encapsulation of L. rhamnosus significantly enhanced their viability under gastrointestinal tract insults. Compared with free cells, encapsulated L. rhamnosus exerted better therapeutic effect against Salmonella-induced enteritis with negligible toxicity in vivo. These results demonstrate that this redox-responsive hydrogel may be a promising encapsulation and delivery system for improving the efficacy of orally administered probiotics.

Supramolecular self-assembled drug delivery system (SADDs) of vancomycin and tocopherol succinate as an antibacterial agent: in vitro, in silico and in vivo evaluations

In this study self-assembled drug delivery system (SADDs) composed of a hydrophobic d-α-tocopherol succinate (TS) and a hydrophilic vancomycin (VCM) were formulated, and its potential for enhancing the antibacterial activity of VCM against Staphylococcus aureus (SA) and Methicillin-resistant Staphylococcus aureus (MRSA) were explored. The SADDs were synthesized via supramolecular complexation, then characterized for in silico, in vitro and in vivo studies. In silico studies confirmed the self-assembly of VCM/TS into NPs. The size, surface charge and drug loading of the SADDs was ˂100 nm, -27 mV and 68%, respectively. The SADDs were non-hemolytic and biosafe. A sustained release of VCM from SADDs was noted, with 52.2% release after 48 hr. The in vitro antibacterial test showed a twofold decrease in Minimum inhibitory concentration (MIC) against SA and MRSA, and a significantly higher reduction in MRSA biofilms compared to bare VCM. Further, in silico studies confirmed strong and stable binding of TS to MRSA efflux pumps. The in vivo study using mice skin infection models showed a 9.5-fold reduction in bacterial load after treatment with SADDs, in comparison with bare VCM. These findings affirmed that VCM/TS NPs as a promising novel nano-delivery for treating bacterial infections.